This commit adds support for the Minerva architecture

Squashed commit of the following: Author: Gregory Nutt <gnutt@nuttx.org> Eliminate complaints from tools/nxstyle Manually fix up kruft left behind by indent.sh Raw application of tools/indent.sh to all new .c and .h files. Still need fixups. Convert all C++ style comments to C style; Covery hex constants to lower case. Convert TABs to spaces Beginning of code review process. The first small dent. configs/misoc: Rename os_start to nx_start. arch/misoc/src/minerva/minerva_exit.c: Make name change to match change made to master. Author: Ramtin Amin <keytwo@gmail.com> configs/Kconfig and misoc/nsh/defconfig: Add support for the Verilator board. Author: Juha Niskanen (Haltian) <juha.niskanen@haltian.com> arch/arm/src/stm32l4/stm32l4_lse.c: Ports Jussi Kivilinna's recent STM32F7 LSE change to STM32L4. Author: David Sidrane <david_s5@usa.net> tools/.gitignore: Ignore new tool binaries. Author: Ramtin Amin <keytwo@gmail.com> arch/misoc/src/minerva: Initial merge of minera port.
2026-05-21 04:52:02 +08:00 · 2019-02-07 09:41:18 -06:00
parent 0344e017f9
commit c7382d9db9
60 changed files with 5388 additions and 826 deletions
@@ -15,17 +15,18 @@ config ARCH_CHIP_LM32
 	---help---
 		LM32 Chip Selected

-config ARCH_CHIP_MOR1K
-	bool "MOR1K"
+config ARCH_CHIP_MINERVA
+	bool "MINERVA"
+	select MISOC_HAVE_UART1
 	---help---
-		MOR1K Chip Selected
+		LambdaConcept MINERVAL Chip Selected

 endchoice # Misoc Chip Selection

 config ARCH_CHIP
 	string
 	default "lm32"		if ARCH_CHIP_LM32
-	default "mor1k"		if ARCH_CHIP_MOR1K
+	default "minerva"	if ARCH_CHIP_MINERVA

 menu "MISOC Peripheral Support"

@@ -72,8 +73,8 @@ config MISOC_UART_TX_BUF_SIZE
 if ARCH_CHIP_LM32
 source arch/misoc/src/lm32/Kconfig
 endif
-if ARCH_CHIP_MOR1K
-#source arch/misoc/src/mor1k/Kconfig
+if ARCH_CHIP_MINERVA
+source arch/misoc/src/minerva/Kconfig
 endif

 endif # ARCH_MISOC
@@ -47,7 +47,12 @@
 #include <nuttx/irq.h>
 #include <arch/chip/irq.h>

-#include <arch/lm32/irq.h>
+#ifdef CONFIG_ARCH_CHIP_LM32
+# include <arch/lm32/irq.h>
+#endif
+#ifdef CONFIG_ARCH_CHIP_MINERVA
+# include <arch/minerva/irq.h>
+#endif

 /****************************************************************************
 * Pre-processor Definitions
@@ -69,8 +74,8 @@ extern "C"
 #endif

 irqstate_t up_irq_save(void);
-void up_irq_restore(irqstate_t flags);
 irqstate_t up_irq_enable(void);
+void up_irq_restore(irqstate_t flags);

 #undef EXTERN
 #ifdef __cplusplus
@@ -0,0 +1,80 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/csrdefs.h
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#ifndef __RISCV_CSR_DEFS__
+#define __RISCV_CSR_DEFS__
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define CSR_MVENDORID_ADDR   0xf11
+#define CSR_MARCHID_ADDR     0xf12
+#define CSR_MIMPID_ADDR      0xf13
+#define CSR_MHARTID_ADDR     0xf14
+#define CSR_MSTATUS_ADDR     0x300
+#define CSR_MISA_ADDR        0x301
+#define CSR_MEDELEG_ADDR     0x302
+#define CSR_MIDELEG_ADDR     0x303
+#define CSR_MIE_ADDR         0x304
+#define CSR_MTVEC_ADDR       0x305
+#define CSR_MCOUTEREN_ADDR   0x306
+#define CSR_MSCRATCH_ADDR    0x340
+#define CSR_MEPC_ADDR        0x341
+#define CSR_MCAUSE_ADDR      0x342
+#define CSR_MTVAL_ADDR       0x343
+#define CSR_MIP_ADDR         0x344
+#define CSR_IRQ_MASK_ADDR    0x330
+#define CSR_IRQ_PENDING_ADDR 0x360
+
+#define CSR_MSTATUS_UIE      (1 << 0)
+#define CSR_MSTATUS_SIE      (1 << 1)
+#define CSR_MSTATUS_MIE      (1 << 3)
+#define CSR_MSTATUS_UPIE     (1 << 4)
+#define CSR_MSTATUS_SPIE     (1 << 5)
+#define CSR_MSTATUS_MPIE     (1 << 7)
+#define CSR_MSTATUS_SPP      (1 << 8)
+#define CSR_MSTATUS_MPP      (1 << 11)
+#define CSR_MSTATUS_FS       (1 << 13)
+#define CSR_MSTATUS_XS       (1 << 15)
+#define CSR_MSTATUS_MPRV     (1 << 17)
+#define CSR_MSTATUS_SUM      (1 << 18)
+#define CSR_MSTATUS_MXR      (1 << 19)
+#define CSR_MSTATUS_TVM      (1 << 20)
+#define CSR_MSTATUS_TW       (1 << 21)
+#define CSR_MSTATUS_TSR      (1 << 22)
+#define CSR_MSTATUS_SD       (1 << 31)
+
+#endif
@@ -0,0 +1,327 @@
+/****************************************************************************
+ * arch/risc-v/include/rv32im/irq.h
+ *
+ *   Copyright (C) 2011, 2013, 2015 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ *  Modified for RISC-V:
+ *
+ *   Copyright (C) 2016 Ken Pettit. All rights reserved.
+ *   Author: Ken Pettit <pettitkd@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/* This file should never be included directed but, rather, only indirectly
+ * through nuttx/irq.h
+ */
+
+#ifndef __ARCH_MINERVA_INCLUDE_IRQ_H
+#define __ARCH_MINERVA_INCLUDE_IRQ_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <arch/types.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* Configuration ************************************************************/
+
+/* If this is a kernel build, how many nested system calls should we support? */
+
+#define MINERVA_NINTERRUPTS 32
+#define MINERVA_IRQ_SWINT   32
+#define NR_IRQS             33
+
+#ifndef CONFIG_SYS_NNEST
+#  define CONFIG_SYS_NNEST 2
+#endif
+
+#define REG_X0_NDX          0
+#define REG_X1_NDX          1
+#define REG_X2_NDX          2
+#define REG_X3_NDX          3
+#define REG_X4_NDX          4
+#define REG_X5_NDX          5
+#define REG_X6_NDX          6
+#define REG_X7_NDX          7
+#define REG_X8_NDX          8
+#define REG_X9_NDX          9
+#define REG_X10_NDX         10
+#define REG_X11_NDX         11
+#define REG_X12_NDX         12
+#define REG_X13_NDX         13
+#define REG_X14_NDX         14
+#define REG_X15_NDX         15
+#define REG_X16_NDX         16
+#define REG_X17_NDX         17
+#define REG_X18_NDX         18
+#define REG_X19_NDX         19
+#define REG_X20_NDX         20
+#define REG_X21_NDX         21
+#define REG_X22_NDX         22
+#define REG_X23_NDX         23
+#define REG_X24_NDX         24
+#define REG_X25_NDX         25
+#define REG_X26_NDX         26
+#define REG_X27_NDX         27
+#define REG_X28_NDX         28
+#define REG_X29_NDX         29
+#define REG_X30_NDX         30
+#define REG_X31_NDX         31
+
+#define REG_CSR_MSTATUS_NDX     32
+#define REG_CSR_MEPC_NDX        33
+#define REG_CSR_MBADADDR_NDX   34
+#define REG_CSR_MCAUSE_NDX      35
+
+#define XCPTCONTEXT_REGS    36
+#define XCPTCONTEXT_SIZE    (4 * XCPTCONTEXT_REGS)
+
+/* In assembly language, values have to be referenced as byte address
+ * offsets.  But in C, it is more convenient to reference registers as
+ * register save table offsets.
+ */
+
+#ifdef __ASSEMBLY__
+#  define REG_X0            (4*REG_X0_NDX)
+#  define REG_X1            (4*REG_X1_NDX)
+#  define REG_X2            (4*REG_X2_NDX)
+#  define REG_X3            (4*REG_X3_NDX)
+#  define REG_X4            (4*REG_X4_NDX)
+#  define REG_X5            (4*REG_X5_NDX)
+#  define REG_X6            (4*REG_X6_NDX)
+#  define REG_X7            (4*REG_X7_NDX)
+#  define REG_X8            (4*REG_X8_NDX)
+#  define REG_X9            (4*REG_X9_NDX)
+#  define REG_X10           (4*REG_X10_NDX)
+#  define REG_X11           (4*REG_X11_NDX)
+#  define REG_X12           (4*REG_X12_NDX)
+#  define REG_X13           (4*REG_X13_NDX)
+#  define REG_X14           (4*REG_X14_NDX)
+#  define REG_X15           (4*REG_X15_NDX)
+#  define REG_X16           (4*REG_X16_NDX)
+#  define REG_X17           (4*REG_X17_NDX)
+#  define REG_X18           (4*REG_X18_NDX)
+#  define REG_X19           (4*REG_X19_NDX)
+#  define REG_X20           (4*REG_X20_NDX)
+#  define REG_X21           (4*REG_X21_NDX)
+#  define REG_X22           (4*REG_X22_NDX)
+#  define REG_X23           (4*REG_X23_NDX)
+#  define REG_X24           (4*REG_X24_NDX)
+#  define REG_X25           (4*REG_X25_NDX)
+#  define REG_X26           (4*REG_X26_NDX)
+#  define REG_X27           (4*REG_X27_NDX)
+#  define REG_X28           (4*REG_X28_NDX)
+#  define REG_X29           (4*REG_X29_NDX)
+#  define REG_X30           (4*REG_X30_NDX)
+#  define REG_X31           (4*REG_X31_NDX)
+#  define REG_CSR_MSTATUS   (4*REG_CSR_MSTATUS_NDX)
+#  define REG_CSR_MEPC      (4*REG_CSR_MEPC_NDX)
+#  define REG_CSR_MBADADDR  (4*REG_CSR_MBADADDR_NDX)
+#  define REG_CSR_MCAUSE    (4*REG_CSR_MCAUSE_NDX)
+#else
+#  define REG_X0            REG_X0_NDX
+#  define REG_X1            REG_X1_NDX
+#  define REG_X2            REG_X2_NDX
+#  define REG_X3            REG_X3_NDX
+#  define REG_X4            REG_X4_NDX
+#  define REG_X5            REG_X5_NDX
+#  define REG_X6            REG_X6_NDX
+#  define REG_X7            REG_X7_NDX
+#  define REG_X8            REG_X8_NDX
+#  define REG_X9            REG_X9_NDX
+#  define REG_X10           REG_X10_NDX
+#  define REG_X11           REG_X11_NDX
+#  define REG_X12           REG_X12_NDX
+#  define REG_X13           REG_X13_NDX
+#  define REG_X14           REG_X14_NDX
+#  define REG_X15           REG_X15_NDX
+#  define REG_X16           REG_X16_NDX
+#  define REG_X17           REG_X17_NDX
+#  define REG_X18           REG_X18_NDX
+#  define REG_X19           REG_X19_NDX
+#  define REG_X20           REG_X20_NDX
+#  define REG_X21           REG_X21_NDX
+#  define REG_X22           REG_X22_NDX
+#  define REG_X23           REG_X23_NDX
+#  define REG_X24           REG_X24_NDX
+#  define REG_X25           REG_X25_NDX
+#  define REG_X26           REG_X26_NDX
+#  define REG_X27           REG_X27_NDX
+#  define REG_X28           REG_X28_NDX
+#  define REG_X29           REG_X29_NDX
+#  define REG_X30           REG_X30_NDX
+#  define REG_X31           REG_X31_NDX
+#  define REG_CSR_MSTATUS   REG_CSR_MSTATUS_NDX
+#  define REG_CSR_MEPC      REG_CSR_MEPC_NDX
+#  define REG_CSR_MBADADDR  REG_CSR_MBADADDR_NDX
+#  define REG_CSR_MCAUSE    REG_CSR_MCAUSE_NDX
+#endif
+
+/* Now define more user friendly alternative name that can be used either
+ * in assembly or C contexts.
+ */
+
+/* $1 = ra: Return address */
+
+#define REG_RA              REG_X1
+
+/* $2 = sp:  The value of the stack pointer on return from the exception */
+
+#define REG_SP              REG_X2
+
+/* $3 = gp: Only needs to be saved under conditions where there are
+ * multiple, per-thread values for the GP.
+ */
+
+#define REG_GP              REG_X3
+
+/* $4 = tp:  Thread Pointer */
+
+#define REG_TP              REG_X4
+
+/* $5-$7 = t0-t2: Caller saved temporary registers */
+
+#define REG_T0              REG_X5
+#define REG_T1              REG_X6
+#define REG_T2              REG_X7
+
+/* $8 = either s0 or fp:  Depends if a frame pointer is used or not */
+
+#define REG_S0              REG_X8
+#define REG_FP              REG_X8
+
+/* $9 = s1: Caller saved register */
+
+#define REG_S1              REG_X9
+
+/* $10-$17 = a0-a7: Argument registers */
+
+#define REG_A0              REG_X10
+#define REG_A1              REG_X11
+#define REG_A2              REG_X12
+#define REG_A3              REG_X13
+#define REG_A4              REG_X14
+#define REG_A5              REG_X15
+#define REG_A6              REG_X16
+#define REG_A7              REG_X17
+
+/* $18-$27 = s2-s11: Callee saved registers */
+
+#define REG_S2              REG_X18
+#define REG_S3              REG_X19
+#define REG_S4              REG_X20
+#define REG_S5              REG_X21
+#define REG_S6              REG_X22
+#define REG_S7              REG_X23
+#define REG_S8              REG_X24
+#define REG_S9              REG_X25
+#define REG_S10             REG_X26
+#define REG_S11             REG_X27
+
+/* $28-$31 = t3-t6: Caller saved temporary registers */
+
+#define REG_T3              REG_X28
+#define REG_T4              REG_X29
+#define REG_T5              REG_X30
+#define REG_T6              REG_X31
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+
+/* This structure represents the return state from a system call */
+
+#ifdef CONFIG_BUILD_KERNEL
+struct xcpt_syscall_s
+{
+  uint32_t sysreturn;         /* The return PC */
+};
+#endif
+
+/* The following structure is included in the TCB and defines the complete
+ * state of the thread.
+ */
+
+struct xcptcontext
+{
+#ifndef CONFIG_DISABLE_SIGNALS
+  /* The following function pointer is non-NULL if there are pending signals
+   * to be processed.
+   */
+
+  void *sigdeliver;           /* Actual type is sig_deliver_t */
+
+  /* These additional register save locations are used to implement the
+   * signal delivery trampoline.
+   */
+
+  uint32_t saved_epc;         /* Trampoline PC */
+  uint32_t saved_int_ctx;     /* Interrupt context with interrupts disabled. */
+
+#ifdef CONFIG_BUILD_KERNEL
+  /* This is the saved address to use when returning from a user-space signal
+   * handler.
+   */
+
+  uint32_t sigreturn;
+
+#endif
+#endif
+
+#ifdef CONFIG_BUILD_KERNEL
+  /* The following array holds information needed to return from each nested
+   * system call.
+   */
+
+  uint8_t nsyscalls;
+  struct xcpt_syscall_s syscall[CONFIG_SYS_NNEST];
+
+#endif
+
+  /* Register save area */
+
+  uint32_t regs[XCPTCONTEXT_REGS];
+};
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#endif /* __ASSEMBLY__ */
+#endif /* __ARCH_RISCV_INCLUDE_RV32IM_IRQ_H */
@@ -0,0 +1,208 @@
+/****************************************************************************
+ * arch/misoc/include/minerva/syscall.h
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/* This file should never be included directed but, rather, only indirectly
+ * through include/syscall.h or include/sys/sycall.h
+ */
+
+#ifndef __ARCH_MISOC_INCLUDE_MINERVA_SYSCALL_H
+#define __ARCH_MISOC_INCLUDE_MINERVA_SYSCALL_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#ifndef __ASSEMBLY__
+#include <stdint.h>
+#endif
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define SYS_syscall 0x00
+
+/* Configuration ************************************************************/
+
+/* SYS call 1 and 2 are defined for internal use by the MINERVA port (see
+ * arch/miscoc/include/minerva/syscall.h).  In addition, SYS call 3 is the
+ * return from a SYS call in kernel mode.  The first four syscall values
+ * must, therefore, be reserved (0 is not used).
+ */
+
+#ifdef CONFIG_BUILD_KERNEL
+#  ifndef CONFIG_SYS_RESERVED
+#    error "CONFIG_SYS_RESERVED must be defined to the value 4"
+#  elif CONFIG_SYS_RESERVED != 4
+#    error "CONFIG_SYS_RESERVED must have the value 4"
+#  endif
+#endif
+
+/* sys_call macros **********************************************************/
+
+#ifndef __ASSEMBLY__
+
+/* Context switching system calls *******************************************/
+
+/* SYS call 0: (not used) */
+
+/* SYS call 1:
+ *
+ * void up_fullcontextrestore(uint32_t *restoreregs) noreturn_function;
+ */
+
+#define SYS_restore_context (1)
+#define up_fullcontextrestore(restoreregs) \
+  (void)sys_call1(SYS_restore_context, (uintptr_t)restoreregs)
+
+/* SYS call 2:
+ *
+ * void up_switchcontext(uint32_t *saveregs, uint32_t *restoreregs);
+ */
+
+#define SYS_switch_context (2)
+#define up_switchcontext(saveregs, restoreregs) \
+  (void)sys_call2(SYS_switch_context, (uintptr_t)saveregs, \
+                  (uintptr_t)restoreregs)
+
+#ifdef CONFIG_BUILD_KERNEL
+
+/* SYS call 3:
+ *
+ * void up_syscall_return(void);
+ */
+
+#define SYS_syscall_return (3)
+#define up_syscall_return() (void)sys_call0(SYS_syscall_return)
+
+#endif
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Inline functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#  define EXTERN extern "C"
+extern "C"
+{
+#else
+#  define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Name: up_syscall0
+ *
+ * Description:
+ *   System call SYS_ argument and no additional parameters.
+ *
+ ****************************************************************************/
+
+uintptr_t sys_call0(unsigned int nbr);
+
+/****************************************************************************
+ * Name: up_syscall1
+ *
+ * Description:
+ *   System call SYS_ argument and one additional parameter.
+ *
+ ****************************************************************************/
+
+uintptr_t sys_call1(unsigned int nbr, uintptr_t parm1);
+
+/****************************************************************************
+ * Name: up_syscall2
+ *
+ * Description:
+ *   System call SYS_ argument and two additional parameters.
+ *
+ ****************************************************************************/
+
+uintptr_t sys_call2(unsigned int nbr, uintptr_t parm1, uintptr_t parm2);
+
+/****************************************************************************
+ * Name: up_syscall3
+ *
+ * Description:
+ *   System call SYS_ argument and three additional parameters.
+ *
+ ****************************************************************************/
+
+uintptr_t sys_call3(unsigned int nbr, uintptr_t parm1, uintptr_t parm2,
+                    uintptr_t parm3);
+
+/****************************************************************************
+ * Name: up_syscall4
+ *
+ * Description:
+ *   System call SYS_ argument and four additional parameters.
+ *
+ ****************************************************************************/
+
+uintptr_t sys_call4(unsigned int nbr, uintptr_t parm1, uintptr_t parm2,
+                    uintptr_t parm3, uintptr_t parm4);
+
+/****************************************************************************
+ * Name: up_syscall5
+ *
+ * Description:
+ *   System call SYS_ argument and five additional parameters.
+ *
+ ****************************************************************************/
+
+uintptr_t sys_call5(unsigned int nbr, uintptr_t parm1, uintptr_t parm2,
+                    uintptr_t parm3, uintptr_t parm4, uintptr_t parm5);
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif  /* __ASSEMBLY__ */
+#endif  /* __ARCH_MISOC_INCLUDE_MINERVA_SYSCALL_H */
@@ -0,0 +1,94 @@
+/****************************************************************************
+ * arch/misoc/include/minerva/types.h
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/* This file should never be included directed but, rather, only indirectly
+ * through stdint.h
+ */
+
+#ifndef __ARCH_MISOC_INCLUDE_MINERVA_TYPES_H
+#define __ARCH_MISOC_INCLUDE_MINERVA_TYPES_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Type Declarations
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+
+/* These are the sizes of the standard integer types.  NOTE that these type
+ * names have a leading underscore character.  This file will be included
+ * (indirectly) by include/stdint.h and typedef'ed to the final name without
+ * the underscore character.  This roundabout way of doings things allows
+ * the stdint.h to be removed from the include/ directory in the event that
+ * the user prefers to use the definitions provided by their toolchain header
+ * files
+ */
+
+typedef signed char _int8_t;
+typedef unsigned char _uint8_t;
+
+typedef signed short _int16_t;
+typedef unsigned short _uint16_t;
+
+typedef signed int _int32_t;
+typedef unsigned int _uint32_t;
+
+typedef signed long long _int64_t;
+typedef unsigned long long _uint64_t;
+#define __INT64_DEFINED
+
+/* A pointer is 4 bytes */
+
+typedef signed int _intptr_t;
+typedef unsigned int _uintptr_t;
+
+/* This is the size of the interrupt state save returned by up_irq_save(). */
+
+typedef unsigned int irqstate_t;
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#endif  /* __ASSEMBLY__ */
+#endif  /* __ARCH_MISOC_INCLUDE_MINERVA_TYPES_H */
@@ -0,0 +1,60 @@
+/****************************************************************************
+ * arch/misoc/include/stdarg.h
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_MISOC_INCLUDE_STDARG_H
+#define __ARCH_MISOC_INCLUDE_STDARG_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* This should work with any modern gcc (newer than 3.4 or so) */
+
+#define va_start(v,l)   __builtin_va_start(v,l)
+#define va_end(v)       __builtin_va_end(v)
+#define va_arg(v,l)     __builtin_va_arg(v,l)
+#define va_copy(d,s)    __builtin_va_copy(d,s)
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+typedef __builtin_va_list va_list;
+
+#endif /* __ARCH_MISOC_INCLUDE_STDARG_H */
@@ -50,4 +50,8 @@
 # include <arch/lm32/syscall.h>
 #endif

+#ifdef CONFIG_ARCH_CHIP_MINERVA
+# include <arch/minerva/syscall.h>
+#endif
+
 #endif /* __ARCH_MISOC_INCLUDE_SYSCALL_H */
@@ -1,7 +1,7 @@
 ############################################################################
 # arch/misoc/src/Makefile
 #
-#   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+#   Copyright (C) 2016, 2019 Gregory Nutt. All rights reserved.
 #   Author: Gregory Nutt <gnutt@nuttx.org>
 #
 # Redistribution and use in source and binary forms, with or without
@@ -36,7 +36,13 @@
 -include $(TOPDIR)/Make.defs
 -include chip/Make.defs

-ARCH_SUBDIR = lm32
+ifeq ($(CONFIG_ARCH_CHIP_LM32),y)
+ ARCH_SUBDIR = lm32
+endif
+
+ifeq ($(CONFIG_ARCH_CHIP_MINERVA),y)
+ ARCH_SUBDIR = minerva
+endif

 ifeq ($(CONFIG_WINDOWS_NATIVE),y)
  ARCH_SRCDIR = $(TOPDIR)\arch\$(CONFIG_ARCH)\src
@@ -1,7 +1,7 @@
 /****************************************************************************
 *  arch/misoc/src/common/hw/common.h
 *
- *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2016, 2019 Gregory Nutt. All rights reserved.
 *   Author: Ramtin Amin <keytwo@gmail.com>
 *
 * Redistribution and use in source and binary forms, with or without
@@ -36,14 +36,63 @@
 #ifndef __ARCH_MISOC_SRC_COMMON_HW_COMMON_H
 #define __ARCH_MISOC_SRC_COMMON_HW_COMMON_H

+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stdint.h>
+
 /****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

+/* To overwrite CSR accessors, define extern, non-inlined versions
+ * of csr_read[bwl]() and csr_write[bwl](), and define
+ * CSR_ACCESSORS_DEFINED.
+ */
+
+#ifndef CSR_ACCESSORS_DEFINED
+#define CSR_ACCESSORS_DEFINED
+
+/****************************************************************************
+ * Inline Functions
+ ****************************************************************************/
+
 #ifdef __ASSEMBLER__
 #  define MMPTR(x) x
 #else
 #  define MMPTR(x) (*((volatile unsigned int *)(x)))
-#endif

+static inline void csr_writeb(uint8_t value, uint32_t addr)
+{
+  *((volatile uint8_t *)addr) = value;
+}
+
+static inline uint8_t csr_readb(uint32_t addr)
+{
+  return *(volatile uint8_t *)addr;
+}
+
+static inline void csr_writew(uint16_t value, uint32_t addr)
+{
+  *((volatile uint16_t *)addr) = value;
+}
+
+static inline uint16_t csr_readw(uint32_t addr)
+{
+  return *(volatile uint16_t *)addr;
+}
+
+static inline void csr_writel(uint32_t value, uint32_t addr)
+{
+  *((volatile uint32_t *)addr) = value;
+}
+
+static inline uint32_t csr_readl(uint32_t addr)
+{
+  return *(volatile uint32_t *)addr;
+}
+
+#endif /* !__ASSEMBLER__ */
+#endif /* !CSR_ACCESSORS_DEFINED */
 #endif /* __ARCH_MISOC_SRC_COMMON_HW_COMMON_H */
@@ -612,6 +612,9 @@ static void misoc_net_interrupt_work(FAR void *arg)

  net_unlock();

+  ethmac_sram_reader_ev_enable_write(1);
+  ethmac_sram_writer_ev_enable_write(1);
+
  /* Re-enable Ethernet interrupts */

  up_enable_irq(ETHMAC_INTERRUPT);
@@ -643,6 +646,9 @@ static int misoc_net_interrupt(int irq, FAR void *context, FAR void *arg)
   * condition here.
   */

+  ethmac_sram_reader_ev_enable_write(0);
+  ethmac_sram_writer_ev_enable_write(0);
+
  /* TODO: Determine if a TX transfer just completed */

  if (ethmac_sram_reader_ev_pending_read() & ETHMAC_EV_SRAM_READER)
@@ -820,6 +826,7 @@ static void misoc_net_poll_expiry(int argc, wdparm_t arg, ...)

 static int misoc_net_ifup(FAR struct net_driver_s *dev)
 {
+  irqstate_t flags;
  FAR struct misoc_net_driver_s *priv = (FAR struct misoc_net_driver_s *)dev->d_private;

 #ifdef CONFIG_NET_IPv4
@@ -844,6 +851,8 @@ static int misoc_net_ifup(FAR struct net_driver_s *dev)
  misoc_net_ipv6multicast(priv);
 #endif

+  flags = enter_critical_section();
+
  /* Set and activate a timer process */

  (void)wd_start(priv->misoc_net_txpoll, MISOC_NET_WDDELAY, misoc_net_poll_expiry, 1,
@@ -855,6 +864,7 @@ static int misoc_net_ifup(FAR struct net_driver_s *dev)
  /* Enable the RX Event Handler */

  ethmac_sram_writer_ev_enable_write(1);
+  leave_critical_section(flags);
  return OK;
 }

@@ -884,6 +894,9 @@ static int misoc_net_ifdown(FAR struct net_driver_s *dev)
  flags = enter_critical_section();
  up_disable_irq(ETHMAC_INTERRUPT);

+  ethmac_sram_reader_ev_enable_write(0);
+  ethmac_sram_writer_ev_enable_write(0);
+
  /* Cancel the TX poll timer and TX timeout timers */

  wd_cancel(priv->misoc_net_txpoll);
@@ -1150,10 +1163,10 @@ int misoc_net_initialize(int intf)
      return -EAGAIN;
    }

-  /* clear pending int */
+  /* Clear pending int */

-  ethmac_sram_writer_ev_pending_write(1);
-  ethmac_sram_reader_ev_pending_write(1);
+  ethmac_sram_reader_ev_pending_write(ETHMAC_EV_SRAM_READER);
+  ethmac_sram_writer_ev_pending_write(ETHMAC_EV_SRAM_WRITER);

  /* Initialize the driver structure */

@@ -130,8 +130,8 @@ void misoc_timer_initialize(void)
   * CLOCKS_PER_SEC.
   */

-  timer0_reload_write(SYSTICK_RELOAD);
-  timer0_load_write(SYSTICK_RELOAD);
+  timer0_reload_write(SYSTICK_RELOAD * 20);
+  timer0_load_write(SYSTICK_RELOAD * 20);

  /* Enable timer */

@@ -85,7 +85,12 @@ static void _up_assert(int errorcode)

  (void)syslog_flush();

-  /* Are we in an interrupt handler or the idle task? */
+  /* Are we in an interrupt handler or the idle task?
+   * NOTE:  You cannot use the PID to determine if this is an IDLE task.  In
+   * the SMP case, there may be multiple IDLE tasks with different PIDs.  The
+   * only consistent way to test for the IDLE task is to check it is at the
+   * end of the list (flink == NULL)
+   */

  if (g_current_regs || running_task()->flink == NULL)
    {
@@ -1,7 +1,7 @@
 /****************************************************************************
 * arch/misoc/src/lm32/lm32_dumpstate.c
 *
- *  Copyright (C) 2011 Gregory Nutt. All rights reserved.
+ *  Copyright (C) 2011, 2019 Gregory Nutt. All rights reserved.
 *  Author: Gregory Nutt <gnutt@nuttx.org>
 *          Ramtin Amin <keytwo@gmail.com>
 *
@@ -85,7 +85,9 @@ void up_initialize(void)
  iob_initialize();
 #endif

+#if 0 /* REVISIT */
  /* Initialize the network cores */

  misoc_net_initialize(0);
+#endif
 }
@@ -123,7 +123,7 @@ void up_irq_restore(irqstate_t flags)
 *
 ****************************************************************************/

-irqstate_t up_irq_restore(irqstate_t flags)
+irqstate_t up_irq_enable(void)
 {
  irqstate_t flags;

@@ -134,7 +134,7 @@ int lm32_swint(int irq, FAR void *context, FAR void *arg)
 {
  uint32_t *regs = (uint32_t *)context;

-  DEBUGASSERT(g_current_regs == NULL);
+  DEBUGASSERT(regs != NULL && regs == g_current_regs);
  g_current_regs = regs;

  /* Software interrupt 0 is invoked with REG_A0 (REG_X10) = system call
@@ -0,0 +1,35 @@
+#
+# For a description of the syntax of this configuration file,
+# see the file kconfig-language.txt in the NuttX tools repository.
+#
+
+if ARCH_CHIP_MINERVA
+
+choice
+	prompt "Toolchain Selection"
+	default MINERVA_TOOLCHAIN_GNUW if TOOLCHAIN_WINDOWS
+	default MINERVA_TOOLCHAIN_GNUL if !TOOLCHAIN_WINDOWS
+
+config MINERVA_TOOLCHAIN_BUILDROOT
+	bool "Buildroot (Cygwin or Linux)"
+	depends on !WINDOWS_NATIVE
+	select ARCH_TOOLCHAIN_GNU
+
+config MINERVA_TOOLCHAIN_GNUL
+	bool "Generic GNU toolchain under Linux (or other POSIX environment)"
+	select ARCH_TOOLCHAIN_GNU
+	---help---
+		This option should work for any modern GNU toolchain (GCC 4.5 or newer)
+		configured for risc64-elf-.
+
+config MINERVA_TOOLCHAIN_GNUW
+	bool "Generic GNU toolchain under Windows"
+	depends on TOOLCHAIN_WINDOWS
+	select ARCH_TOOLCHAIN_GNU
+	---help---
+		This option should work for any modern GNU toolchain (GCC 4.5 or newer)
+		configured for risc64-elf-.
+
+endchoice # Toolchain Selection
+
+endif # ARCH_CHIP_MINERVA
@@ -0,0 +1,55 @@
+############################################################################
+# arch/misoc/src/Makefile
+#
+#   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <gnutt@nuttx.org>
+#           Ramtin Amin <keytwo@gmail.com>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name NuttX nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+
+HEAD_ASRC   = minerva_vectors.S
+
+CMN_ASRCS   =
+CMN_CSRCS   = misoc_lowputs.c misoc_serial.c misoc_mdelay.c
+CMN_CSRCS  += misoc_modifyreg8.c misoc_modifyreg16.c misoc_modifyreg32.c
+CMN_CSRCS  += misoc_puts.c misoc_udelay.c misoc_timerisr.c misoc_net.c
+CMN_CSRCS  += misoc_flushcache.c
+
+CHIP_ASRCS  = minerva_syscall.S
+
+CHIP_CSRCS  = minerva_allocateheap.c minerva_assert.c minerva_blocktask.c
+CHIP_CSRCS += minerva_copystate.c minerva_createstack.c minerva_decodeirq.c
+CHIP_CSRCS += minerva_doirq.c minerva_dumpstate.c minerva_exit.c minerva_idle.c
+CHIP_CSRCS += minerva_initialize.c minerva_initialstate.c minerva_interruptcontext.c
+CHIP_CSRCS += minerva_irq.c minerva_releasepending.c minerva_releasestack.c
+CHIP_CSRCS += minerva_stackframe.c minerva_swint.c minerva_unblocktask.c
+CHIP_CSRCS += minerva_reprioritizertr.c minerva_schedulesigaction.c minerva_sigdeliver.c
+CHIP_CSRCS += minerva_flushcache.c minerva_doexceptions.c
+
@@ -0,0 +1,44 @@
+############################################################################
+# arch/misoc/src/minerva/Toolchain.defs
+#
+#   Copyright (C) 2012-2013, 2015 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <gnutt@nuttx.org>
+#
+#   modified for RISC-V:
+#
+#   Copyright (C) 2016 Ken Pettit. All rights reserved.
+#   Author: Ken Pettit <pettitkd@gmail.com>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+
+CROSSDEV = riscv32-unknown-elf-
+ARCROSSDEV = riscv32-unknown-elf-
+ARCHCPUFLAGS = -march=rv32i
+
+ifeq ($(CONFIG_DEBUG_SYMBOLS),)
+MAXOPTIMIZATION ?= -Os
+endif
@@ -0,0 +1,138 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/chip.h
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_MISOC_SRC_MINERVA_CHIP_H
+#define __ARCH_MISOC_SRC_MINERVA_CHIP_H 1
+
+/****************************************************************************
+ * Inline Functions
+ ****************************************************************************/
+
+#include "minerva.h"
+#include <arch/minerva/csrdefs.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define CSR_IRQ_MASK 0x330
+#define CSR_IRQ_PENDING 0x360
+
+#define CSR_DCACHE_INFO 0xcc0
+
+#define csrr(reg) \
+  ({ \
+     unsigned long __tmp; \
+     asm volatile ("csrr %0, " #reg : "=r"(__tmp)); \
+     __tmp; \
+  })
+
+#define csrw(reg, val) \
+  ({ \
+     if (__builtin_constant_p(val) && (unsigned long)(val) < 32) \
+       { \
+          asm volatile ("csrw " #reg ", %0" :: "i"(val)); \
+       } \
+     else \
+       { \
+          asm volatile ("csrw " #reg ", %0" :: "r"(val)); \
+       } \
+   })
+
+#define csrs(reg, bit) \
+  ({ \
+     if (__builtin_constant_p(bit) && (unsigned long)(bit) < 32) \
+       { \
+        asm volatile ("csrrs x0, " #reg ", %0" :: "i"(bit)); \
+       } \
+     else \
+       { \
+        asm volatile ("csrrs x0, " #reg ", %0" :: "r"(bit)); \
+       } \
+   })
+
+#define csrc(reg, bit) \
+  ({ \
+     if (__builtin_constant_p(bit) && (unsigned long)(bit) < 32) \
+       { \
+         asm volatile ("csrrc x0, " #reg ", %0" :: "i"(bit)); \
+       } \
+     else \
+       { \
+         asm volatile ("csrrc x0, " #reg ", %0" :: "r"(bit)); \
+       } \
+   })
+
+/****************************************************************************
+ * Inline Functions
+ ****************************************************************************/
+
+static inline unsigned int irq_getie(void)
+{
+  return (csrr(mstatus) & CSR_MSTATUS_MIE) != 0;
+}
+
+static inline void irq_setie(unsigned int ie)
+{
+  if (ie)
+    csrs(mstatus, CSR_MSTATUS_MIE);
+  else
+    csrc(mstatus, CSR_MSTATUS_MIE);
+}
+
+static inline unsigned int irq_getmask(void)
+{
+  unsigned int mask;
+  asm volatile ("csrr %0, %1":"=r" (mask):"i"(CSR_IRQ_MASK));
+  return mask;
+}
+
+static inline void irq_setmask(unsigned int mask)
+{
+  asm volatile ("csrw %0, %1"::"i" (CSR_IRQ_MASK), "r"(mask));
+}
+
+static inline unsigned int irq_pending(void)
+{
+  unsigned int pending;
+  asm volatile ("csrr %0, %1":"=r" (pending):"i"(CSR_IRQ_PENDING));
+  return pending;
+}
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#endif  /* __ARCH_MISOC_SRC_MINERVA_CHIP_H */
@@ -0,0 +1,162 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva.h
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_MISOC_SRC_MINERVA_MINERVA_H
+#define __ARCH_MISOC_SRC_MINERVA_MINERVA_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#ifndef __ASSEMBLY__
+#  include <nuttx/compiler.h>
+#  include <sys/types.h>
+#  include <stdint.h>
+#endif
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* This is the value used to mark the stack for subsequent stack monitoring
+ * logic.
+ */
+
+#define STACK_COLOR             0xdeadbeef
+#define INTSTACK_COLOR          0xdeadbeef
+#define HEAP_COLOR              'h'
+
+/* In the MINERVA model, the state is copied from the stack to the TCB, but
+ * only a referenced is passed to get the state from the TCB.
+ */
+
+#define up_savestate(regs)      minerva_copystate(regs, (uint32_t*)g_current_regs)
+#define up_copystate(rega,regb) minerva_copystate(rega, regb)
+#define up_restorestate(regs)   (g_current_regs = regs)
+
+/* Determine which (if any) console driver to use.  If a console is enabled
+ * and no other console device is specified, then a serial console is
+ * assumed.
+ */
+
+#if !defined(CONFIG_DEV_CONSOLE) || CONFIG_NFILE_DESCRIPTORS <= 0
+#  undef  USE_SERIALDRIVER
+#  undef  USE_EARLYSERIALINIT
+#  undef  CONFIG_DEV_LOWCONSOLE
+#  undef  CONFIG_RAMLOG_CONSOLE
+#else
+#  if defined(CONFIG_RAMLOG_CONSOLE)
+#    undef  USE_SERIALDRIVER
+#    undef  USE_EARLYSERIALINIT
+#    undef  CONFIG_DEV_LOWCONSOLE
+#  elif defined(CONFIG_DEV_LOWCONSOLE)
+#    undef  USE_SERIALDRIVER
+#    undef  USE_EARLYSERIALINIT
+#  else
+#    define USE_SERIALDRIVER 1
+#    define USE_EARLYSERIALINIT 1
+#  endif
+#endif
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+
+extern volatile uint32_t *g_current_regs;
+extern uint32_t g_idle_topstack;
+
+/****************************************************************************
+ * Inline Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/* Low level initialization provided by board-level logic ******************/
+
+void minerva_board_initialize(void);
+
+/* Memory allocation ********************************************************/
+
+#if CONFIG_MM_REGIONS > 1
+void minerva_add_region(void);
+#endif
+
+/* Context switching ********************************************************/
+
+void minerva_copystate(uint32_t * dest, uint32_t * src);
+
+/* IRQ initialization *******************************************************/
+
+void minerva_irq_initialize(void);
+
+/* Interrupt decode *********************************************************/
+
+uint32_t *minerva_decodeirq(uint32_t intstat, uint32_t * regs);
+uint32_t *minerva_doirq(int irq, uint32_t * regs);
+
+/* Software interrupts ******************************************************/
+
+int minerva_swint(int irq, FAR void *context, FAR void *arg);
+
+/* System timer *************************************************************/
+
+void minerva_timer_initialize(void);
+
+/* Signal handling **********************************************************/
+
+void minerva_sigdeliver(void);
+
+/* Cache flushing ***********************************************************/
+
+void minerva_flush_dcache(void);
+void minerva_flush_icache(void);
+
+/* Debug ********************************************************************/
+
+void minerva_dumpstate(void);
+
+#endif  /* __ASSEMBLY__ */
+#endif  /* __ARCH_MISOC_SRC_MINERVA_MINERVA_H */
@@ -0,0 +1,92 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_allocateheap.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/board.h>
+#include <arch/board/board.h>
+
+#include "minerva.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_allocate_heap
+ *
+ * Description:
+ *   This function will be called to dynamically set aside the heap region.
+ *
+ *   For the kernel build (CONFIG_BUILD_KERNEL=y) with both kernel- and
+ *   user-space heaps (CONFIG_MM_KERNEL_HEAP=y), this function provides the
+ *   size of the unprotected, user-space heap.
+ *
+ *   If a protected kernel-space heap is provided, the kernel heap must be
+ *   allocated (and protected) by an analogous up_allocate_kheap().
+ *
+ ****************************************************************************/
+
+void up_allocate_heap(FAR void **heap_start, size_t * heap_size)
+{
+  board_autoled_on(LED_HEAPALLOCATE);
+  *heap_start = (FAR void *)g_idle_topstack;
+  *heap_size = CONFIG_RAM_END - g_idle_topstack;
+}
+
+/****************************************************************************
+ * Name: minerva_add_region
+ *
+ * Description:
+ *   Memory may be added in non-contiguous chunks.  Additional chunks are
+ *   added by calling this function.
+ *
+ ****************************************************************************/
+
+#if CONFIG_MM_REGIONS > 1
+void minerva_add_region(void)
+{
+#  warning Missing logic
+}
+#endif
@@ -0,0 +1,189 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_assert.c
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <nuttx/board.h>
+#include <nuttx/syslog/syslog.h>
+#include <nuttx/usb/usbdev_trace.h>
+
+#include <arch/board/board.h>
+
+#include "sched/sched.h"
+#include "minerva.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* USB trace dumping */
+
+#ifndef CONFIG_USBDEV_TRACE
+#  undef CONFIG_ARCH_USBDUMP
+#endif
+
+#ifndef CONFIG_BOARD_RESET_ON_ASSERT
+#  define CONFIG_BOARD_RESET_ON_ASSERT 0
+#endif
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: _up_assert
+ ****************************************************************************/
+
+static void _up_assert(int errorcode) noreturn_function;
+static void _up_assert(int errorcode)
+{
+  /* Flush any buffered SYSLOG data */
+
+  (void)syslog_flush();
+
+  /* Are we in an interrupt handler or the idle task? NOTE: You cannot use the
+   * PID to determine if this is an IDLE task.  In the SMP case, there may be
+   * multiple IDLE tasks with different PIDs.  The only consistent way to test
+   * for the IDLE task is to check it is at the end of the list (flink ==
+   * NULL)
+   */
+
+  if (g_current_regs || running_task()->flink == NULL)
+    {
+      (void)up_irq_save();
+      for (; ; )
+        {
+#if CONFIG_BOARD_RESET_ON_ASSERT >= 1
+          board_reset(CONFIG_BOARD_ASSERT_RESET_VALUE);
+#endif
+#ifdef CONFIG_ARCH_LEDS
+          board_autoled_on(LED_PANIC);
+          up_mdelay(250);
+          board_autoled_off(LED_PANIC);
+          up_mdelay(250);
+#endif
+        }
+    }
+  else
+    {
+#if CONFIG_BOARD_RESET_ON_ASSERT >= 2
+      board_reset(CONFIG_BOARD_ASSERT_RESET_VALUE);
+#endif
+      exit(errorcode);
+    }
+}
+
+/****************************************************************************
+ * Name: assert_tracecallback
+ ****************************************************************************/
+
+#ifdef CONFIG_ARCH_USBDUMP
+static int usbtrace_syslog(FAR const char *fmt, ...)
+{
+  va_list ap;
+  int ret;
+
+  /* Let nx_vsyslog do the real work */
+
+  va_start(ap, fmt);
+  ret = nx_vsyslog(LOG_EMERG, fmt, &ap);
+  va_end(ap);
+  return ret;
+}
+
+static int assert_tracecallback(FAR struct usbtrace_s *trace, FAR void *arg)
+{
+  usbtrace_trprintf(usbtrace_syslog, trace->event, trace->value);
+  return 0;
+}
+#endif
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_assert
+ ****************************************************************************/
+
+void up_assert(const uint8_t * filename, int lineno)
+{
+#if CONFIG_TASK_NAME_SIZE > 0 && defined(CONFIG_DEBUG_ALERT)
+  struct tcb_s *rtcb = running_task();
+#endif
+
+  board_autoled_on(LED_ASSERTION);
+
+  /* Flush any buffered SYSLOG data (prior to the assertion) */
+
+  (void)syslog_flush();
+
+#if CONFIG_TASK_NAME_SIZE > 0
+  _alert("Assertion failed at file:%s line: %d task: %s\n",
+         filename, lineno, rtcb->name);
+#else
+  _alert("Assertion failed at file:%s line: %d\n", filename, lineno);
+#endif
+
+  minerva_dumpstate();
+
+#ifdef CONFIG_ARCH_USBDUMP
+  /* Dump USB trace data */
+
+  (void)usbtrace_enumerate(assert_tracecallback, NULL);
+#endif
+
+  /* Flush any buffered SYSLOG data (from the above) */
+
+  (void)syslog_flush();
+
+#ifdef CONFIG_BOARD_CRASHDUMP
+  board_crashdump(up_getsp(), running_task(), filename, lineno);
+#endif
+
+  _up_assert(EXIT_FAILURE);
+}
@@ -0,0 +1,177 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_blocktask.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdbool.h>
+#include <sched.h>
+#include <syscall.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/sched.h>
+
+#include "sched/sched.h"
+#include "group/group.h"
+#include "minerva.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_block_task
+ *
+ * Description:
+ *   The currently executing task at the head of
+ *   the ready to run list must be stopped.  Save its context
+ *   and move it to the inactive list specified by task_state.
+ *
+ * Input Parameters:
+ *   tcb: Refers to a task in the ready-to-run list (normally
+ *     the task at the head of the list).  It most be
+ *     stopped, its context saved and moved into one of the
+ *     waiting task lists.  It it was the task at the head
+ *     of the ready-to-run list, then a context to the new
+ *     ready to run task must be performed.
+ *   task_state: Specifies which waiting task list should be
+ *     hold the blocked task TCB.
+ *
+ ****************************************************************************/
+
+void up_block_task(struct tcb_s *tcb, tstate_t task_state)
+{
+  struct tcb_s *rtcb = this_task();
+  bool switch_needed;
+
+  /* Verify that the context switch can be performed */
+
+  DEBUGASSERT((tcb->task_state >= FIRST_READY_TO_RUN_STATE) &&
+              (tcb->task_state <= LAST_READY_TO_RUN_STATE));
+
+  /* Remove the tcb task from the ready-to-run list.  If we are blocking the
+   * task at the head of the task list (the most likely case), then a context
+   * switch to the next ready-to-run task is needed. In this case, it should
+   * also be true that rtcb == tcb.
+   */
+
+  switch_needed = sched_removereadytorun(tcb);
+
+  /* Add the task to the specified blocked task list */
+
+  sched_addblocked(tcb, (tstate_t) task_state);
+
+  /* If there are any pending tasks, then add them to the ready-to-run task
+   * list now
+   */
+
+  if (g_pendingtasks.head)
+    {
+      switch_needed |= sched_mergepending();
+    }
+
+  /* Now, perform the context switch if one is needed */
+
+  if (switch_needed)
+    {
+      /* Update scheduler parameters */
+
+      sched_suspend_scheduler(rtcb);
+
+      /* Are we in an interrupt handler? */
+
+      if (g_current_regs)
+        {
+          /* Yes, then we have to do things differently. Just copy the
+           * g_current_regs into the OLD rtcb.
+           */
+
+          up_savestate(rtcb->xcp.regs);
+
+          /* Restore the exception context of the rtcb at the (new) head of
+           * the ready-to-run task list.
+           */
+
+          rtcb = this_task();
+
+          /* Reset scheduler parameters */
+
+          sched_resume_scheduler(rtcb);
+
+          /* Then switch contexts.  Any necessary address environment changes
+           * will be made when the interrupt returns.
+           */
+
+          up_restorestate(rtcb->xcp.regs);
+        }
+
+      /* No, then we will need to perform the user context switch */
+
+      else
+        {
+          /* Get the context of the task at the head of the ready to run list. */
+
+          struct tcb_s *nexttcb = this_task();
+
+#ifdef CONFIG_ARCH_ADDRENV
+          /* Make sure that the address environment for the previously running
+           * task is closed down gracefully (data caches dump, MMU flushed)
+           * and set up the address environment for the new thread at the head
+           * of the ready-to-run list.
+           */
+
+          (void)group_addrenv(nexttcb);
+#endif
+          /* Reset scheduler parameters */
+
+          sched_resume_scheduler(nexttcb);
+
+          /* Then switch contexts */
+
+          up_switchcontext(rtcb->xcp.regs, nexttcb->xcp.regs);
+
+          /* up_switchcontext forces a context switch to the task at the head
+           * of the ready-to-run list.  It does not 'return' in the normal
+           * sense.  When it does return, it is because the blocked task is
+           * again ready to run and has execution priority.
+           */
+        }
+    }
+}
@@ -0,0 +1,82 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_config.h
+ *
+ *   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Modified for MINERVA:
+ *
+ *   Copyright (C) 2016 Ramin Amin. All rights reserved.
+ *   Author: Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_MISOC_SRC_MINERVA_MINERVA_CONFIG_H
+#define __ARCH_MISOC_SRC_MINERVA_MINERVA_CONFIG_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <arch/chip/chip.h>
+#include <arch/board/board.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* UARTs ********************************************************************/
+
+/* Are any UARTs enabled? */
+
+#undef HAVE_UART_DEVICE
+#if defined(CONFIG_MISOC_UART1) || defined(CONFIG_MISOC_UART2)
+#  define HAVE_UART_DEVICE 1
+#endif
+
+/* Is there a serial console?  There should be no more than one defined.  It
+ * could be on any UARTn, n=1,.. CHIP_NUARTS
+ */
+
+#if defined(CONFIG_UART1_SERIAL_CONSOLE) && defined(CONFIG_MISOC_UART1)
+#  undef CONFIG_UART2_SERIAL_CONSOLE
+#  define HAVE_SERIAL_CONSOLE 1
+#elif defined(CONFIG_UART2_SERIAL_CONSOLE) && defined(CONFIG_MISOC_UART2)
+#  undef CONFIG_UART1_SERIAL_CONSOLE
+#  define HAVE_SERIAL_CONSOLE 1
+#else
+#  undef CONFIG_UART1_SERIAL_CONSOLE
+#  undef CONFIG_UART2_SERIAL_CONSOLE
+#  undef HAVE_SERIAL_CONSOLE
+#endif
+
+#endif  /* __ARCH_MISOC_SRC_MINERVA_MINERVA_CONFIG_H */
@@ -0,0 +1,74 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_copystate.c
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <arch/irq.h>
+
+#include "minerva.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: minerva_copystate
+ ****************************************************************************/
+
+/* A little faster than most memcpy's */
+
+void minerva_copystate(uint32_t * dest, uint32_t * src)
+{
+  int i;
+
+  /* In the MINERVA model, the state is copied from the stack to the TCB, but
+   * only a reference is passed to get the state from the TCB.  So the
+   * following check avoids copying the TCB save area onto itself:
+   */
+
+  if (src != dest)
+    {
+      for (i = 0; i < XCPTCONTEXT_REGS; i++)
+        {
+          *dest++ = *src++;
+        }
+    }
+}
@@ -0,0 +1,206 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_createstack.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/kmalloc.h>
+#include <nuttx/arch.h>
+#include <nuttx/board.h>
+#include <arch/board/board.h>
+
+#include "minerva.h"
+
+/****************************************************************************
+ * Pre-processor Macros
+ ****************************************************************************/
+
+/* MINERVA requires at least a 4-byte stack alignment.  For floating point
+ * use, however, the stack must be aligned to 8-byte addresses.
+ */
+
+#ifdef CONFIG_LIBC_FLOATINGPOINT
+#  define STACK_ALIGNMENT   8
+#else
+#  define STACK_ALIGNMENT   4
+#endif
+
+/* Stack alignment macros */
+
+#define STACK_ALIGN_MASK    (STACK_ALIGNMENT-1)
+#define STACK_ALIGN_DOWN(a) ((a) & ~STACK_ALIGN_MASK)
+#define STACK_ALIGN_UP(a)   (((a) + STACK_ALIGN_MASK) & ~STACK_ALIGN_MASK)
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_create_stack
+ *
+ * Description:
+ *   Allocate a stack for a new thread and setup up stack-related information
+ *   in the TCB.
+ *
+ *   The following TCB fields must be initialized by this function:
+ *
+ *   - adj_stack_size: Stack size after adjustment for hardware, processor,
+ *     etc.  This value is retained only for debug purposes.
+ *   - stack_alloc_ptr: Pointer to allocated stack
+ *   - adj_stack_ptr: Adjusted stack_alloc_ptr for HW.  The initial value of
+ *     the stack pointer.
+ *
+ * Input Parameters:
+ *   - tcb: The TCB of new task
+ *   - stack_size:  The requested stack size.  At least this much
+ *     must be allocated.
+ *   - ttype:  The thread type.  This may be one of following (defined in
+ *     include/nuttx/sched.h):
+ *
+ *       TCB_FLAG_TTYPE_TASK     Normal user task
+ *       TCB_FLAG_TTYPE_PTHREAD  User pthread
+ *       TCB_FLAG_TTYPE_KERNEL   Kernel thread
+ *
+ *     This thread type is normally available in the flags field of the TCB,
+ *     however, there are certain contexts where the TCB may not be fully
+ *     initialized when up_create_stack is called.
+ *
+ *     If CONFIG_BUILD_KERNEL is defined, then this thread type may affect
+ *     how the stack is allocated.  For example, kernel thread stacks should
+ *     be allocated from protected kernel memory.  Stacks for user tasks and
+ *     threads must come from memory that is accessible to user code.
+ *
+ ****************************************************************************/
+
+int up_create_stack(FAR struct tcb_s *tcb, size_t stack_size, uint8_t ttype)
+{
+  /* Is there already a stack allocated of a different size? Because of
+   * alignment issues, stack_size might erroneously appear to be of a
+   * different size.  Fortunately, this is not a critical operation.
+   */
+
+  if (tcb->stack_alloc_ptr && tcb->adj_stack_size != stack_size)
+    {
+      /* Yes.. Release the old stack */
+
+      up_release_stack(tcb, ttype);
+    }
+
+  /* Do we need to allocate a new stack? */
+
+  if (!tcb->stack_alloc_ptr)
+    {
+      /* Allocate the stack.  If DEBUG is enabled (but not stack debug), then
+       * create a zeroed stack to make stack dumps easier to trace.
+       */
+
+#if defined(CONFIG_BUILD_KERNEL) && defined(CONFIG_MM_KERNEL_HEAP)
+      /* Use the kernel allocator if this is a kernel thread */
+
+      if (ttype == TCB_FLAG_TTYPE_KERNEL)
+        {
+          tcb->stack_alloc_ptr = (uint32_t *) kmm_malloc(stack_size);
+        }
+      else
+#endif
+        {
+          /* Use the user-space allocator if this is a task or pthread */
+
+          tcb->stack_alloc_ptr = (uint32_t *) kumm_malloc(stack_size);
+        }
+
+#ifdef CONFIG_DEBUG_FEATURES
+      /* Was the allocation successful? */
+
+      if (!tcb->stack_alloc_ptr)
+        {
+          serr("ERROR: Failed to allocate stack, size %d\n", stack_size);
+        }
+#endif
+    }
+
+  /* Did we successfully allocate a stack? */
+
+  if (tcb->stack_alloc_ptr)
+    {
+      size_t top_of_stack;
+      size_t size_of_stack;
+
+      /* Yes.. If stack debug is enabled, then fill the stack with a
+       * recognizable value that we can use later to test for high water
+       * marks.
+       */
+
+#ifdef CONFIG_STACK_COLORATION
+      memset(tcb->stack_alloc_ptr, 0xaa, stack_size);
+#endif
+
+      /* MINERVA uses a push-down stack: the stack grows toward lower
+       * addresses in memory.  The stack pointer register points to the
+       * lowest, valid working address (the "top" of the stack).  Items on
+       * the stack are referenced as positive word offsets from sp.
+       */
+
+      top_of_stack = (uint32_t) tcb->stack_alloc_ptr + stack_size - 4;
+
+      /* The MINERVA stack must be aligned at word (4 byte) boundaries; for
+       * floating point use, the stack must be aligned to 8-byte addresses. If
+       * necessary top_of_stack must be rounded down to the next boundary to
+       * meet these alignment requirements.
+       */
+
+      top_of_stack = STACK_ALIGN_DOWN(top_of_stack);
+      size_of_stack = top_of_stack - (uint32_t) tcb->stack_alloc_ptr + 4;
+
+      /* Save the adjusted stack values in the struct tcb_s */
+
+      tcb->adj_stack_ptr = (FAR uint32_t *) top_of_stack;
+      tcb->adj_stack_size = size_of_stack;
+
+      board_autoled_on(LED_STACKCREATED);
+      return OK;
+    }
+
+  return ERROR;
+}
@@ -0,0 +1,107 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_decodeirq.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <debug.h>
+
+#include <arch/irq.h>
+
+#include "chip.h"
+#include "minerva.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: minerva_decodeirq
+ *
+ * Description:
+ *   This function is called from the IRQ vector handler in minerva_vectors.S.
+ *   At this point, the interrupt has been taken and the registers have
+ *   been saved on the stack.  This function simply needs to determine the
+ *   the irq number of the interrupt and then to call minerva_doirq to
+ *   dispatch the interrupt.
+ *
+ *  Input parameters:
+ *   regs - A pointer to the register save area on the stack.
+ *
+ ****************************************************************************/
+
+uint32_t *minerva_decodeirq(uint32_t intstat, uint32_t * regs)
+{
+  int irq;
+
+  irqinfo("intstat=%08lx\n", (unsigned long)intstat);
+
+  /* Decode and dispatch interrupts */
+
+  for (irq = 0; irq < MINERVA_NINTERRUPTS && intstat != 0; irq++)
+    {
+      uint32_t bit = (1 << irq);
+
+      /* Is this interrupt pending? */
+
+      if ((intstat & bit) != 0)
+        {
+          /* Yes.. Dispatch the interrupt
+           * REVIST: Do I need to acknowledge the interrupt first?
+           */
+
+          irqinfo("irq=%d\n", irq);
+          regs = minerva_doirq(irq, regs);
+
+          /* Clear the bit in the interrupt status copy so that maybe we can
+           * break out of the loop early.
+           */
+
+          intstat &= ~bit;
+        }
+    }
+
+  /* Return the final task register save area.  This will typically be the
+   * same as the value of regs on input.  In the event of a context switch,
+   * however, it will differ.  It will refere to the register save are in
+   * the TCB of the new thread.
+   */
+
+  return regs;
+}
@@ -0,0 +1,93 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_doexception.c
+ *
+ *   Copyright (C) 2018 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <nuttx/board.h>
+
+#include <arch/irq.h>
+#include <arch/board/board.h>
+
+#include "group/group.h"
+#include "minerva.h"
+#include "chip.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+uint32_t *minerva_doexception(uint32_t * regs)
+{
+  uint32_t mcause;
+  uint32_t pending;
+  uint32_t *ret;
+
+  board_autoled_on(LED_INIRQ);
+
+  mcause = regs[REG_CSR_MCAUSE_NDX];
+
+  if (mcause & 0x80000000)
+    {
+      pending = irq_pending();
+      ret = minerva_decodeirq(pending, regs);
+    }
+  else
+    {
+      mcause = mcause & 0x7fffffff;
+      if (mcause == 11)
+        {
+          regs[REG_CSR_MEPC_NDX] += 4;
+          ret = minerva_doirq(MINERVA_IRQ_SWINT, regs);
+        }
+      else
+        {
+          while (1);
+        }
+    }
+
+  board_autoled_off(LED_INIRQ);
+  return ret;
+}
@@ -0,0 +1,130 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_doirq.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <nuttx/board.h>
+
+#include <arch/irq.h>
+#include <arch/board/board.h>
+
+#include "group/group.h"
+#include "minerva.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+uint32_t *minerva_doirq(int irq, uint32_t * regs)
+{
+  board_autoled_on(LED_INIRQ);
+
+  /* Current regs non-zero indicates that we are processing an interrupt;
+   * g_current_regs is also used to manage interrupt level context switches.
+   * Nested interrupts are not supported
+   */
+
+  DEBUGASSERT(g_current_regs == NULL);
+  g_current_regs = regs;
+
+  /* Disable further occurrences of this interrupt (until the interrupt
+   * sources have been clear by the driver).
+   */
+
+  up_disable_irq(irq);
+
+  /* Deliver the IRQ */
+
+  irq_dispatch(irq, regs);
+
+#if defined(CONFIG_ARCH_FPU) || defined(CONFIG_ARCH_ADDRENV)
+  /* Check for a context switch.  If a context switch occurred, then
+   * g_current_regs will have a different value than it did on entry.  If an
+   * interrupt level context switch has occurred, then restore the floating
+   * point state and the establish the correct address environment before
+   * returning from the interrupt.
+   */
+
+  if (regs != g_current_regs)
+    {
+#  ifdef CONFIG_ARCH_FPU
+      /* Restore floating point registers */
+
+      up_restorefpu((uint32_t *) g_current_regs);
+#  endif
+
+#  ifdef CONFIG_ARCH_ADDRENV
+      /* Make sure that the address environment for the previously running
+       * task is closed down gracefully (data caches dump, MMU flushed) and
+       * set up the address environment for the new thread at the head of
+       * the ready-to-run list.
+       */
+
+      (void)group_addrenv(NULL);
+#  endif
+    }
+#endif
+
+  /* If a context switch occurred while processing the interrupt then
+   * g_current_regs may have change value.  If we return any value different
+   * from the input regs, then the lower level will know that a context switch
+   * occurred during interrupt processing.
+   */
+
+  regs = (uint32_t *) g_current_regs;
+
+  /* Set g_current_regs to NULL to indicate that we are no longer in an
+   * interrupt handler.
+   */
+
+  g_current_regs = NULL;
+
+  /* Unmask the last interrupt (global interrupts are still disabled) */
+
+  up_enable_irq(irq);
+  board_autoled_off(LED_INIRQ);
+  return regs;
+}
@@ -0,0 +1,232 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_dumpstate.c
+ *
+ *  Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *  Author: Gregory Nutt <gnutt@nuttx.org>
+ *          Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <arch/board/board.h>
+
+#include "sched/sched.h"
+#include "minerva.h"
+
+#ifdef CONFIG_ARCH_STACKDUMP
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_getsp
+ ****************************************************************************/
+
+static inline uint32_t up_getsp(void)
+{
+  register uint32_t sp;
+
+  __asm__ __volatile__("addi %0, sp, 0":"=r"(sp));
+
+  return sp;
+}
+
+/****************************************************************************
+ * Name: up_stackdump
+ ****************************************************************************/
+
+static void up_stackdump(uint32_t sp, uint32_t stack_base)
+{
+  uint32_t stack;
+
+  for (stack = sp & ~0x1f; stack < stack_base; stack += 32)
+    {
+      uint32_t *ptr = (uint32_t *) stack;
+      _alert("%08x: %08x %08x %08x %08x %08x %08x %08x %08x\n",
+             stack, ptr[0], ptr[1], ptr[2], ptr[3],
+             ptr[4], ptr[5], ptr[6], ptr[7]);
+    }
+}
+
+/****************************************************************************
+ * Name: up_registerdump
+ ****************************************************************************/
+
+static inline void up_registerdump(void)
+{
+  /* Are user registers available from interrupt processing? */
+
+  if (g_current_regs)
+    {
+      _alert("EPC:%08x \n", g_current_regs[REG_CSR_MEPC]);
+      _alert
+        (" X0:%08x  A0:%08x  A1:%08x  A2:%08x  A3:%08x  A4:%08x  A5:%08x  A6:%08x\n",
+         g_current_regs[REG_X0_NDX], g_current_regs[REG_X1_NDX],
+         g_current_regs[REG_X2_NDX], g_current_regs[REG_X3_NDX],
+         g_current_regs[REG_X4_NDX], g_current_regs[REG_X5_NDX],
+         g_current_regs[REG_X6_NDX], g_current_regs[REG_X7_NDX]);
+      _alert
+        (" A7:%08x  X9:%08x X10:%08x X11:%08x X12:%08x X13:%08x X14:%08x X15:%08x\n",
+         g_current_regs[REG_X8_NDX], g_current_regs[REG_X9_NDX],
+         g_current_regs[REG_X10_NDX], g_current_regs[REG_X11_NDX],
+         g_current_regs[REG_X12_NDX], g_current_regs[REG_X13_NDX],
+         g_current_regs[REG_X14_NDX], g_current_regs[REG_X15_NDX]);
+      _alert
+        ("X16:%08x X17:%08x X18:%08x X19:%08x X20:%08x X21:%08x X22:%08x X23:%08x\n",
+         g_current_regs[REG_X16_NDX], g_current_regs[REG_X17_NDX],
+         g_current_regs[REG_X18_NDX], g_current_regs[REG_X19_NDX],
+         g_current_regs[REG_X20_NDX], g_current_regs[REG_X21_NDX],
+         g_current_regs[REG_X22_NDX], g_current_regs[REG_X23_NDX]);
+      _alert
+        ("X24:%08x X25:%08x  GP:%08x  FP:%08x  SP:%08x  RA:%08x  EA:%08x  BA:%08x\n",
+         g_current_regs[REG_X24_NDX], g_current_regs[REG_X25_NDX],
+         g_current_regs[REG_X26_NDX], g_current_regs[REG_X27_NDX],
+         g_current_regs[REG_X28_NDX], g_current_regs[REG_X29_NDX],
+         g_current_regs[REG_X30_NDX], g_current_regs[REG_X31_NDX]);
+      _alert(" IE:%08x\n", g_current_regs[REG_CSR_MSTATUS]);
+    }
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: minerva_dumpstate
+ ****************************************************************************/
+
+void minerva_dumpstate(void)
+{
+  struct tcb_s *rtcb = running_task();
+  uint32_t sp = up_getsp();
+  uint32_t ustackbase;
+  uint32_t ustacksize;
+#if CONFIG_ARCH_INTERRUPTSTACK > 3
+  uint32_t istackbase;
+  uint32_t istacksize;
+#endif
+
+  /* Dump the registers (if available) */
+
+  up_registerdump();
+
+  /* Get the limits on the user stack memory NOTE: You cannot use the PID to
+   * determine if this is an IDLE task.  In the SMP case, there may be
+   * multiple IDLE tasks with different PIDs.  The only consistent way to
+   * test for the IDLE task is to check it is at the end of the list (flink
+   * == NULL)
+   */
+
+  if (rtcb->flink == NULL)
+    {
+      ustackbase = g_idle_topstack - 4;
+      ustacksize = CONFIG_IDLETHREAD_STACKSIZE;
+    }
+  else
+    {
+      ustackbase = (uint32_t) rtcb->adj_stack_ptr;
+      ustacksize = (uint32_t) rtcb->adj_stack_size;
+    }
+
+  /* Get the limits on the interrupt stack memory */
+
+#if CONFIG_ARCH_INTERRUPTSTACK > 3
+  istackbase = (uint32_t) & g_intstackbase;
+  istacksize = (CONFIG_ARCH_INTERRUPTSTACK & ~3) - 4;
+
+  /* Show interrupt stack info */
+
+  _alert("sp:     %08x\n", sp);
+  _alert("IRQ stack:\n");
+  _alert("  base: %08x\n", istackbase);
+  _alert("  size: %08x\n", istacksize);
+
+  /* Does the current stack pointer lie within the interrupt stack? */
+
+  if (sp <= istackbase && sp > istackbase - istacksize)
+    {
+      /* Yes.. dump the interrupt stack */
+
+      up_stackdump(sp, istackbase);
+
+      /* Extract the user stack pointer which should lie at the base of the
+       * interrupt stack.
+       */
+
+      sp = g_intstackbase;
+      _alert("sp:     %08x\n", sp);
+    }
+  else if (g_current_regs)
+    {
+      _alert("ERROR: Stack pointer is not within the interrupt stack\n");
+      up_stackdump(istackbase - istacksize, istackbase);
+    }
+
+  /* Show user stack info */
+
+  _alert("User stack:\n");
+  _alert("  base: %08x\n", ustackbase);
+  _alert("  size: %08x\n", ustacksize);
+#else
+  _alert("sp:         %08x\n", sp);
+  _alert("stack base: %08x\n", ustackbase);
+  _alert("stack size: %08x\n", ustacksize);
+#endif
+
+  /* Dump the user stack if the stack pointer lies within the allocated user
+   * stack memory.
+   */
+
+  if (sp > ustackbase || sp <= ustackbase - ustacksize)
+    {
+      _alert("ERROR: Stack pointer is not within allocated stack\n");
+      up_stackdump(ustackbase - ustacksize, ustackbase);
+    }
+  else
+    {
+      up_stackdump(sp, ustackbase);
+    }
+}
+
+#endif  /* CONFIG_ARCH_STACKDUMP */
+
@@ -0,0 +1,187 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_exit.c
+ *
+ *   Copyright (C) 2010, 2013-2014, 2017-2018 Gregory Nutt. All rights
+ *     reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/irq.h>
+#ifdef CONFIG_DUMP_ON_EXIT
+#  include <nuttx/fs/fs.h>
+#endif
+
+#include <arch/syscall.h>
+
+#include "task/task.h"
+#include "sched/sched.h"
+#include "group/group.h"
+#include "minerva.h"
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: _up_dumponexit
+ *
+ * Description:
+ *   Dump the state of all tasks whenever on task exits.  This is debug
+ *   instrumentation that was added to check file-related reference counting
+ *   but could be useful again sometime in the future.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_DUMP_ON_EXIT
+static void _up_dumponexit(FAR struct tcb_s *tcb, FAR void *arg)
+{
+#if CONFIG_NFILE_DESCRIPTORS > 0
+  FAR struct filelist *filelist;
+#if CONFIG_NFILE_STREAMS > 0
+  FAR struct streamlist *streamlist;
+#endif
+  int i;
+#endif
+
+  sinfo("  TCB=%p name=%s pid=%d\n", tcb, tcb->argv[0], tcb->pid);
+  sinfo("    priority=%d state=%d\n", tcb->sched_priority, tcb->task_state);
+
+#if CONFIG_NFILE_DESCRIPTORS > 0
+  filelist = tcb->group->tg_filelist;
+  for (i = 0; i < CONFIG_NFILE_DESCRIPTORS; i++)
+    {
+      struct inode *inode = filelist->fl_files[i].f_inode;
+      if (inode)
+        {
+          sinfo("      fd=%d refcount=%d\n", i, inode->i_crefssinfo);
+        }
+    }
+#endif
+
+#if CONFIG_NFILE_STREAMS > 0
+  streamlist = tcb->group->tg_streamlist;
+  for (i = 0; i < CONFIG_NFILE_STREAMS; i++)
+    {
+      struct file_struct *filep = &streamlist->sl_streams[i];
+      if (filep->fs_fd >= 0)
+        {
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+          if (filep->fs_bufstart != NULL)
+            {
+              sinfo("      fd=%d nbytes=%d\n",
+                    filep->fs_fd, filep->fs_bufpos - filep->fs_bufstart);
+            }
+          else
+#endif
+            {
+              sinfo("      fd=%d\n", filep->fs_fd);
+            }
+        }
+    }
+#endif
+}
+#endif
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: _exit
+ *
+ * Description:
+ *   This function causes the currently executing task to cease
+ *   to exist.  This is a special case of task_delete() where the task to
+ *   be deleted is the currently executing task.  It is more complex because
+ *   a context switch must be perform to the next ready to run task.
+ *
+ ****************************************************************************/
+
+void _exit(int status)
+{
+  struct tcb_s *tcb = this_task();
+
+  /* Make sure that we are in a critical section with local interrupts.  The
+   * IRQ state will be restored when the next task is started.
+   */
+
+  (void)enter_critical_section();
+
+  sinfo("TCB=%p exiting\n", tcb);
+
+#ifdef CONFIG_DUMP_ON_EXIT
+  sinfo("Other tasks:\n");
+  sched_foreach(_up_dumponexit, NULL);
+#endif
+
+  /* Update scheduler parameters */
+
+  sched_suspend_scheduler(tcb);
+
+  /* Destroy the task at the head of the ready to run list. */
+
+  (void)nxtask_exit();
+
+  /* Now, perform the context switch to the new ready-to-run task at the head
+   * of the list.
+   */
+
+  tcb = this_task();
+
+#ifdef CONFIG_ARCH_ADDRENV
+  /* Make sure that the address environment for the previously running task is
+   * closed down gracefully (data caches dump, MMU flushed) and set up the
+   * address environment for the new thread at the head of the ready-to-run
+   * list.
+   */
+
+  (void)group_addrenv(tcb);
+#endif
+
+  /* Reset scheduler parameters */
+
+  sched_resume_scheduler(tcb);
+
+  /* Then switch contexts */
+
+  up_fullcontextrestore(tcb->xcp.regs);
+}
@@ -0,0 +1,75 @@
+/****************************************************************************
+ *  arch/misoc/src/minerva/minerva_flushcache.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/arch.h>
+
+#include "chip.h"
+#include "minerva.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: minerva_flush_dcache
+ *
+ * Description:
+ *   Flush the data cache of the cpu
+ *
+ ****************************************************************************/
+
+void minerva_flush_dcache(void)
+{
+#warning "FIX D CACHE FLUSH"
+  asm volatile ("nop\n" "nop\n" "nop\n" "nop\n");
+}
+
+/****************************************************************************
+ * Name: minerva_flush_icache
+ *
+ * Description:
+ *   Flush the instruction cache of the cpu
+ *
+ ****************************************************************************/
+
+void minerva_flush_icache(void)
+{
+  asm volatile ("fence.i\n" "nop\n" "nop\n" "nop\n" "nop\n");
+}
@@ -0,0 +1,94 @@
+/****************************************************************************
+ *  arch/misoc/src/minerva/minerva_idle.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+
+#include "minerva.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_idle
+ *
+ * Description:
+ *   up_idle() is the logic that will be executed when their is no other
+ *   ready-to-run task.  This is processor idle time and will continue until
+ *   some interrupt occurs to cause a context switch from the idle task.
+ *
+ *   Processing in this state may be processor-specific. e.g., this is where
+ *   power management operations might be performed.
+ *
+ ****************************************************************************/
+
+void up_idle(void)
+{
+#if defined(CONFIG_SUPPRESS_INTERRUPTS) || defined(CONFIG_SUPPRESS_TIMER_INTS)
+  /* If the system is idle and there are no timer interrupts, then process
+   * "fake" timer interrupts. Hopefully, something will wake up.
+   */
+
+  sched_process_timer();
+#else
+
+  /* This would be an appropriate place to put some MCU-specific logic to
+   * sleep in a reduced power mode until an interrupt occurs to save power
+   *
+   * This is a kludge that I still don't understand.  The call to
+   * kmm_trysemaphore() in the nx_start.c IDLE loop seems necessary for the
+   * good health of the IDLE loop.  When the work queue is enabled, this logic
+   * is removed from the IDLE loop and it appears that we are somehow left
+   * idling with interrupts non- functional. The following should be no-op, it
+   * just disables then re-enables interrupts.  But it fixes the problem and
+   * will stay here until I understand the problem/fix better. And no, the
+   * contents of the CP0 status register are not incorrect.  But for some
+   * reason the status register needs to be re-written again on this thread
+   * for it to take effect.
+   */
+
+#ifdef CONFIG_SCHED_WORKQUEUE
+  irqstate_t flags = enter_critical_section();
+  leave_critical_section(flags);
+#endif
+#endif
+}
@@ -0,0 +1,93 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_initialize.c
+ *
+ *   Copyright (C) 2016-2017 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/sched_note.h>
+#include <nuttx/mm/iob.h>
+#include <nuttx/drivers/drivers.h>
+#include <nuttx/fs/loop.h>
+#include <nuttx/net/loopback.h>
+#include <nuttx/net/tun.h>
+#include <nuttx/net/telnet.h>
+#include <nuttx/syslog/syslog.h>
+#include <nuttx/syslog/syslog_console.h>
+#include <nuttx/serial/pty.h>
+#include <nuttx/crypto/crypto.h>
+#include <nuttx/power/pm.h>
+
+#include <arch/board/board.h>
+
+#include "misoc.h"
+#include "minerva.h"
+
+/****************************************************************************
+ * Public Functionis
+ ****************************************************************************/
+
+void up_initialize(void)
+{
+  /* Initialize the System Timer */
+
+  minerva_irq_initialize();
+
+  /* Initialize the serial driver */
+
+  misoc_serial_initialize();
+
+  /* Initialize the system timer */
+
+  misoc_timer_initialize();
+
+#ifdef CONFIG_MM_IOB
+  /* Initialize IO buffering */
+
+  iob_initialize();
+#endif
+
+  /* Initialize the network cores */
+
+#ifdef CONFIG_MISOC_ETHERNET
+  misoc_net_initialize(0);
+#endif
+}
@@ -0,0 +1,112 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/up_initialstate.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <nuttx/arch.h>
+#include <arch/irq.h>
+#include <arch/minerva/csrdefs.h>
+#include <arch/minerva/irq.h>
+
+#include "minerva.h"
+#include "chip.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_initial_state
+ *
+ * Description:
+ *   A new thread is being started and a new TCB
+ *   has been created. This function is called to initialize
+ *   the processor specific portions of the new TCB.
+ *
+ *   This function must setup the intial architecture registers
+ *   and/or  stack so that execution will begin at tcb->start
+ *   on the next context switch.
+ *
+ ****************************************************************************/
+
+void up_initial_state(struct tcb_s *tcb)
+{
+  uint32_t regval;
+  struct xcptcontext *xcp = &tcb->xcp;
+
+  /* Initialize the initial exception register context structure */
+
+  memset(xcp, 0, sizeof(struct xcptcontext));
+
+  /* Save the initial stack pointer.  Hmmm.. the stack is set to the very
+   * beginning of the stack region.  Some functions may want to store data on
+   * the caller's stack and it might be good to reserve some space.  However,
+   * only the start function would do that and we have control over that one.
+   */
+
+  xcp->regs[REG_SP] = (uint32_t) tcb->adj_stack_ptr;
+
+  /* Save the task entry point */
+
+  xcp->regs[REG_CSR_MEPC] = (uint32_t) tcb->start;
+
+  xcp->regs[REG_CSR_MSTATUS] = CSR_MSTATUS_MPIE;
+
+  /* If this task is running PIC, then set the PIC base register to the
+   * address of the allocated D-Space region.
+   */
+
+#ifdef CONFIG_PIC
+#  warning "Missing logic"
+#endif
+
+  /* Set privileged- or unprivileged-mode, depending on how NuttX is
+   * configured and what kind of thread is being started. If the kernel
+   * build is not selected, then all threads run in privileged thread mode.
+   */
+
+#ifdef CONFIG_BUILD_KERNEL
+#  warning "Missing logic"
+#endif
+}
@@ -0,0 +1,62 @@
+/****************************************************************************
+ *  arch/misoc/src/minerva/up_interruptcontext.c
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdbool.h>
+#include <nuttx/arch.h>
+
+#include "minerva.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_interrupt_context
+ *
+ * Description: Return true is we are currently executing in
+ * the interrupt handler context.
+ ****************************************************************************/
+
+bool up_interrupt_context(void)
+{
+  return g_current_regs != NULL;
+}
@@ -0,0 +1,189 @@
+/****************************************************************************
+ *  arch/misoc/src/minerva/_irq.c
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <stdint.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <arch/irq.h>
+
+#include "chip.h"
+#include "minerva.h"
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+volatile uint32_t *g_current_regs;
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: minerva_irq_initialize
+ ****************************************************************************/
+
+void minerva_irq_initialize(void)
+{
+  /* currents_regs is non-NULL only while processing an interrupt */
+
+  g_current_regs = NULL;
+
+  /* Attach the software interrupt */
+
+  (void)irq_attach(MINERVA_IRQ_SWINT, minerva_swint, NULL);
+
+  /* Enable interrupts */
+
+  irq_setie(1);
+}
+
+/****************************************************************************
+ * Name: up_irq_save
+ *
+ * Description:
+ *   Return the current interrupt enable state and disable all interrupts.
+ *
+ ****************************************************************************/
+
+irqstate_t up_irq_save(void)
+{
+  irqstate_t flags;
+
+  /* Get the previous value of IE */
+
+  flags = irq_getie();
+
+  /* Disable interrupts and return the previous interrupt state */
+
+  irq_setie(0);
+  return flags;
+}
+
+/****************************************************************************
+ * Name: up_irq_restore
+ *
+ * Description:
+ *   Restore saved interrupt state
+ *
+ ****************************************************************************/
+
+void up_irq_restore(irqstate_t flags)
+{
+  /* Restore the interrupt state returned by up_save_irq() */
+
+  irq_setie(flags);
+}
+
+/****************************************************************************
+ * Name: up_irq_enable
+ *
+ * Description:
+ *   Return the current interrupt enable state and enable all interrupts
+ *
+ ****************************************************************************/
+
+irqstate_t up_irq_enable(void)
+{
+  irqstate_t flags;
+
+  /* Get the previous value of IE */
+
+  flags = irq_getie();
+
+  /* Enable interrupts and return the previous interrupt state */
+
+  irq_setie(1);
+  return flags;
+}
+
+/****************************************************************************
+ * Name: up_disable_irq
+ *
+ * Description:
+ *   Disable the IRQ specified by 'irq'
+ *
+ ****************************************************************************/
+
+void up_disable_irq(int irq)
+{
+  irqstate_t flags;
+
+  DEBUGASSERT(irq >= 0 && irq < NR_IRQS);
+
+  /* Ignore any attempt to disable software interrupts */
+
+  if (irq < MINERVA_NINTERRUPTS)
+    {
+      /* Disable interrupts by clearing the bit that corresponds to the irq */
+
+      flags = irq_getmask();
+      flags &= ~(1 << irq);
+      irq_setmask(flags);
+    }
+}
+
+/****************************************************************************
+ * Name: up_enable_irq
+ *
+ * Description:
+ *   Enable the IRQ specified by 'irq'
+ *
+ ****************************************************************************/
+
+void up_enable_irq(int irq)
+{
+  irqstate_t flags;
+  DEBUGASSERT(irq >= 0 && irq < NR_IRQS);
+
+  /* Ignore any attempt to enable software interrupts */
+
+  if (irq < MINERVA_NINTERRUPTS)
+    {
+      /* Enable interrupts by setting the bit that corresponds to the irq */
+
+      flags = irq_getmask();
+      flags |= (1 << irq);
+      irq_setmask(flags);
+    }
+}
@@ -0,0 +1,148 @@
+/****************************************************************************
+ *  arch/misoc/src/minerva/minerva_releasepending.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sched.h>
+#include <syscall.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/sched.h>
+
+#include "sched/sched.h"
+#include "group/group.h"
+#include "minerva.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_release_pending
+ *
+ * Description:
+ *   Release and ready-to-run tasks that have
+ *   collected in the pending task list.  This can call a
+ *   context switch if a new task is placed at the head of
+ *   the ready to run list.
+ *
+ ****************************************************************************/
+
+void up_release_pending(void)
+{
+  struct tcb_s *rtcb = this_task();
+
+  sinfo("From TCB=%p\n", rtcb);
+
+  /* Merge the g_pendingtasks list into the ready-to-run task list */
+
+  /* sched_lock(); */
+
+  if (sched_mergepending())
+    {
+      /* The currently active task has changed! We will need to switch
+       * contexts. Update scheduler parameters.
+       */
+
+      sched_suspend_scheduler(rtcb);
+
+      /* Are we operating in interrupt context? */
+
+      if (g_current_regs)
+        {
+          /* Yes, then we have to do things differently. Just copy the
+           * g_current_regs into the OLD rtcb.
+           */
+
+          up_savestate(rtcb->xcp.regs);
+
+          /* Restore the exception context of the rtcb at the (new) head of
+           * the ready-to-run task list.
+           */
+
+          rtcb = this_task();
+
+          /* Update scheduler parameters */
+
+          sched_resume_scheduler(rtcb);
+
+          /* Then switch contexts.  Any necessary address environment changes
+           * will be made when the interrupt returns.
+           */
+
+          up_restorestate(rtcb->xcp.regs);
+        }
+
+      /* No, then we will need to perform the user context switch */
+
+      else
+        {
+          /* Switch context to the context of the task at the head of the
+           * ready to run list.
+           */
+
+          struct tcb_s *nexttcb = this_task();
+
+#ifdef CONFIG_ARCH_ADDRENV
+          /* Make sure that the address environment for the previously running
+           * task is closed down gracefully (data caches dump, MMU flushed)
+           * and set up the address environment for the new thread at the head
+           * of the ready-to-run list.
+           */
+
+          (void)group_addrenv(nexttcb);
+#endif
+          /* Update scheduler parameters */
+
+          sched_resume_scheduler(nexttcb);
+
+          /* Then switch contexts */
+
+          up_switchcontext(rtcb->xcp.regs, nexttcb->xcp.regs);
+
+          /* up_switchcontext forces a context switch to the task at the head
+           * of the ready-to-run list.  It does not 'return' in the normal
+           * sense.  When it does return, it is because the blocked task is
+           * again ready to run and has execution priority.
+           */
+        }
+    }
+}
@@ -0,0 +1,121 @@
+/****************************************************************************
+ *  arch/misoc/src/minerva/up_releasestack.c
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/kmalloc.h>
+
+#include "minerva.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_release_stack
+ *
+ * Description:
+ *   A task has been stopped. Free all stack related resources retained in
+ *   the defunct TCB.
+ *
+ * Input Parameters:
+ *   - dtcb:  The TCB containing information about the stack to be released
+ *   - ttype:  The thread type.  This may be one of following (defined in
+ *     include/nuttx/sched.h):
+ *
+ *       TCB_FLAG_TTYPE_TASK     Normal user task
+ *       TCB_FLAG_TTYPE_PTHREAD  User pthread
+ *       TCB_FLAG_TTYPE_KERNEL   Kernel thread
+ *
+ *     This thread type is normally available in the flags field of the TCB,
+ *     however, there are certain error recovery contexts where the TCB may
+ *     not be fully initialized when up_release_stack is called.
+ *
+ *     If CONFIG_BUILD_KERNEL is defined, then this thread type may affect
+ *     how the stack is freed.  For example, kernel thread stacks may have
+ *     been allocated from protected kernel memory.  Stacks for user tasks
+ *     and threads must have come from memory that is accessible to user
+ *     code.
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void up_release_stack(FAR struct tcb_s *dtcb, uint8_t ttype)
+{
+  /* Is there a stack allocated? */
+
+  if (dtcb->stack_alloc_ptr)
+    {
+#if defined(CONFIG_BUILD_KERNEL) && defined(CONFIG_MM_KERNEL_HEAP)
+      /* Use the kernel allocator if this is a kernel thread */
+
+      if (ttype == TCB_FLAG_TTYPE_KERNEL)
+        {
+          if (kmm_heapmember(dtcb->stack_alloc_ptr))
+            {
+              sched_kfree(dtcb->stack_alloc_ptr);
+            }
+        }
+      else
+#endif
+        {
+          /* Use the user-space allocator if this is a task or pthread */
+
+          if (umm_heapmember(dtcb->stack_alloc_ptr))
+            {
+              sched_ufree(dtcb->stack_alloc_ptr);
+            }
+        }
+
+      /* Mark the stack freed */
+
+      dtcb->stack_alloc_ptr = NULL;
+    }
+
+  /* The size of the allocated stack is now zero */
+
+  dtcb->adj_stack_size = 0;
+}
@@ -0,0 +1,201 @@
+/****************************************************************************
+ *  arch/misoc/src/minerva/minerva_reprioritizertr.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <sched.h>
+#include <syscall.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/sched.h>
+
+#include "sched/sched.h"
+#include "group/group.h"
+#include "minerva.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_reprioritize_rtr
+ *
+ * Description:
+ *   Called when the priority of a running or
+ *   ready-to-run task changes and the reprioritization will
+ *   cause a context switch.  Two cases:
+ *
+ *   1) The priority of the currently running task drops and the next
+ *      task in the ready to run list has priority.
+ *   2) An idle, ready to run task's priority has been raised above the
+ *      the priority of the current, running task and it now has the
+ *      priority.
+ *
+ * Input Parameters:
+ *   tcb: The TCB of the task that has been reprioritized
+ *   priority: The new task priority
+ *
+ ****************************************************************************/
+
+void up_reprioritize_rtr(struct tcb_s *tcb, uint8_t priority)
+{
+  /* Verify that the caller is sane */
+
+  if (tcb->task_state < FIRST_READY_TO_RUN_STATE ||
+      tcb->task_state > LAST_READY_TO_RUN_STATE
+#if SCHED_PRIORITY_MIN > 0
+      || priority < SCHED_PRIORITY_MIN
+#endif
+#if SCHED_PRIORITY_MAX < UINT8_MAX
+      || priority > SCHED_PRIORITY_MAX
+#endif
+    )
+    {
+      DEBUGPANIC();
+    }
+  else
+    {
+      struct tcb_s *rtcb = this_task();
+      bool switch_needed;
+
+      sinfo("TCB=%p PRI=%d\n", tcb, priority);
+
+      /* Remove the tcb task from the ready-to-run list. sched_removereadytorun
+       * will return true if we just remove the head of the ready to run list.
+       */
+
+      switch_needed = sched_removereadytorun(tcb);
+
+      /* Setup up the new task priority */
+
+      tcb->sched_priority = (uint8_t) priority;
+
+      /* Return the task to the specified blocked task list.
+       * sched_addreadytorun will return true if the task was added to the new
+       * list.  We will need to perform a context switch only if the EXCLUSIVE
+       * or of the two calls is non-zero (i.e., one and only one the calls
+       * changes the head of the ready-to-run list).
+       */
+
+      switch_needed ^= sched_addreadytorun(tcb);
+
+      /* Now, perform the context switch if one is needed */
+
+      if (switch_needed)
+        {
+          /* If we are going to do a context switch, then now is the right
+           * time to add any pending tasks back into the ready-to-run list
+           * task list now.
+           */
+
+          if (g_pendingtasks.head)
+            {
+              sched_mergepending();
+            }
+
+          /* Update scheduler parameters */
+
+          sched_suspend_scheduler(rtcb);
+
+          /* Are we in an interrupt handler? */
+
+          if (g_current_regs)
+            {
+              /* Yes, then we have to do things differently. Just copy the
+               * g_current_regs into the OLD rtcb.
+               */
+
+              up_savestate(rtcb->xcp.regs);
+
+              /* Restore the exception context of the rtcb at the (new) head
+               * of the ready-to-run task list.
+               */
+
+              rtcb = this_task();
+
+              /* Update scheduler parameters */
+
+              sched_resume_scheduler(rtcb);
+
+              /* Then switch contexts.  Any necessary address environment
+               * changes will be made when the interrupt returns.
+               */
+
+              up_restorestate(rtcb->xcp.regs);
+            }
+
+          /* No, then we will need to perform the user context switch */
+
+          else
+            {
+              /* Switch context to the context of the task at the head of the
+               * ready to run list.
+               */
+
+              struct tcb_s *nexttcb = this_task();
+
+#ifdef CONFIG_ARCH_ADDRENV
+              /* Make sure that the address environment for the previously
+               * running task is closed down gracefully (data caches dump, MMU
+               * flushed) and set up the address environment for the new
+               * thread at the head of the ready-to-run list.
+               */
+
+              (void)group_addrenv(nexttcb);
+#endif
+              /* Update scheduler parameters */
+
+              sched_resume_scheduler(nexttcb);
+
+              /* Then switch contexts */
+
+              up_switchcontext(rtcb->xcp.regs, nexttcb->xcp.regs);
+
+              /* up_switchcontext forces a context switch to the task at the
+               * head of the ready-to-run list.  It does not 'return' in the
+               * normal sense.  When it does return, it is because the blocked
+               * task is again ready to run and has execution priority.
+               */
+            }
+        }
+    }
+}
@@ -0,0 +1,202 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_schedulesigaction.c
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ *   Modified for MISOC:
+ *
+ *   Copyright (C) 2016 Ramtin Amin. All rights reserved.
+ *   Author: Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <arch/minerva/irq.h>
+#include <arch/minerva/csrdefs.h>
+
+#include "sched/sched.h"
+#include "minerva.h"
+
+#ifndef CONFIG_DISABLE_SIGNALS
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_schedule_sigaction
+ *
+ * Description:
+ *   This function is called by the OS when one or more
+ *   signal handling actions have been queued for execution.
+ *   The architecture specific code must configure things so
+ *   that the 'igdeliver' callback is executed on the thread
+ *   specified by 'tcb' as soon as possible.
+ *
+ *   This function may be called from interrupt handling logic.
+ *
+ *   This operation should not cause the task to be unblocked
+ *   nor should it cause any immediate execution of sigdeliver.
+ *   Typically, a few cases need to be considered:
+ *
+ *   (1) This function may be called from an interrupt handler
+ *       During interrupt processing, all xcptcontext structures
+ *       should be valid for all tasks.  That structure should
+ *       be modified to invoke sigdeliver() either on return
+ *       from (this) interrupt or on some subsequent context
+ *       switch to the recipient task.
+ *   (2) If not in an interrupt handler and the tcb is NOT
+ *       the currently executing task, then again just modify
+ *       the saved xcptcontext structure for the recipient
+ *       task so it will invoke sigdeliver when that task is
+ *       later resumed.
+ *   (3) If not in an interrupt handler and the tcb IS the
+ *       currently executing task -- just call the signal
+ *       handler now.
+ *
+ ****************************************************************************/
+
+void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver)
+{
+  irqstate_t flags;
+
+  sinfo("tcb=0x%p sigdeliver=0x%p\n", tcb, sigdeliver);
+
+  /* Make sure that interrupts are disabled */
+
+  flags = enter_critical_section();
+
+  /* Refuse to handle nested signal actions */
+
+  if (!tcb->xcp.sigdeliver)
+    {
+      /* First, handle some special cases when the signal is being delivered
+       * to the currently executing task.
+       */
+
+      sinfo("rtcb=0x%p g_current_regs=0x%p\n", this_task(), g_current_regs);
+
+      if (tcb == this_task())
+        {
+          /* CASE 1: We are not in an interrupt handler and a task is
+           * signalling itself for some reason.
+           */
+
+          if (!g_current_regs)
+            {
+              /* In this case just deliver the signal now. */
+
+              sigdeliver(tcb);
+            }
+
+          /* CASE 2: We are in an interrupt handler AND the interrupted task
+           * is the same as the one that must receive the signal, then we
+           * will have to modify the return state as well as the state in
+           * the TCB.
+           *
+           * Hmmm... there looks like a latent bug here: The following logic
+           * would fail in the strange case where we are in an interrupt
+           * handler, the thread is signalling itself, but a context switch to
+           * another task has occurred so that g_current_regs does not refer
+           * to the thread of this_task()!
+           */
+
+          else
+            {
+              /* Save the return EPC and STATUS registers.  These will be
+               * restored by the signal trampoline after the signals have been
+               * delivered.
+               */
+
+              tcb->xcp.sigdeliver = sigdeliver;
+              tcb->xcp.saved_epc = g_current_regs[REG_CSR_MEPC];
+
+              /* Then set up to vector to the trampoline with interrupts
+               * disabled
+               */
+
+              g_current_regs[REG_CSR_MEPC] = (uint32_t) minerva_sigdeliver;
+              g_current_regs[REG_CSR_MSTATUS] &= ~CSR_MSTATUS_MIE;
+
+              /* And make sure that the saved context in the TCB is the same
+               * as the interrupt return context.
+               */
+
+              up_savestate(tcb->xcp.regs);
+
+              sinfo("PC/STATUS Saved: %08x/%08x New: %08x/%08x\n",
+                    tcb->xcp.saved_epc, tcb->xcp.saved_status,
+                    g_current_regs[REG_CSR_MEPC],
+                    g_current_regs[REG_CSR_MSTATUS]);
+            }
+        }
+
+      /* Otherwise, we are (1) signaling a task is not running from an
+       * interrupt handler or (2) we are not in an interrupt handler and the
+       * running task is signalling some non-running task.
+       */
+
+      else
+        {
+          /* Save the return EPC and STATUS registers.  These will be restored
+           * by the signal trampoline after the signals have been delivered.
+           */
+
+          tcb->xcp.sigdeliver = sigdeliver;
+          tcb->xcp.saved_epc = tcb->xcp.regs[REG_CSR_MEPC];
+          tcb->xcp.saved_int_ctx = tcb->xcp.regs[REG_CSR_MSTATUS];
+
+          /* Then set up to vector to the trampoline with interrupts disabled */
+
+          tcb->xcp.regs[REG_CSR_MEPC] = (uint32_t) minerva_sigdeliver;
+          g_current_regs[REG_CSR_MSTATUS] &= ~CSR_MSTATUS_MIE;
+
+          sinfo("PC/STATUS Saved: %08x/%08x New: %08x/%08x\n",
+                tcb->xcp.saved_epc, tcb->xcp.saved_status,
+                tcb->xcp.regs[REG_CSR_MEPC], tcb->xcp.regs[REG_CSR_MSTATUS]);
+        }
+    }
+
+  leave_critical_section(flags);
+}
+
+#endif  /* !CONFIG_DISABLE_SIGNALS */
@@ -0,0 +1,139 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_sigdeliver.c
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <sched.h>
+#include <syscall.h>
+#include <debug.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <nuttx/board.h>
+#include <arch/board/board.h>
+#include <arch/minerva/csrdefs.h>
+
+#include "sched/sched.h"
+#include "minerva.h"
+
+#ifndef CONFIG_DISABLE_SIGNALS
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: minerva_sigdeliver
+ *
+ * Description:
+ *   This is the a signal handling trampoline.  When a signal action was
+ *   posted.  The task context was mucked with and forced to branch to this
+ *   location with interrupts disabled.
+ *
+ ****************************************************************************/
+
+void minerva_sigdeliver(void)
+{
+  struct tcb_s *rtcb = this_task();
+  uint32_t regs[XCPTCONTEXT_REGS];
+  sig_deliver_t sigdeliver;
+
+  /* Save the errno.  This must be preserved throughout the signal handling so
+   * that the user code final gets the correct errno value (probably EINTR).
+   */
+
+  int saved_errno = rtcb->pterrno;
+
+  board_autoled_on(LED_SIGNAL);
+
+  sinfo("rtcb=%p sigdeliver=%p sigpendactionq.head=%p\n",
+        rtcb, rtcb->xcp.sigdeliver, rtcb->sigpendactionq.head);
+  DEBUGASSERT(rtcb->xcp.sigdeliver != NULL);
+
+  /* Save the real return state on the stack. */
+
+  up_copystate(regs, rtcb->xcp.regs);
+  regs[REG_CSR_MEPC] = rtcb->xcp.saved_epc;
+  regs[REG_CSR_MSTATUS] = rtcb->xcp.saved_int_ctx;
+
+  /* Get a local copy of the sigdeliver function pointer. We do this so that
+   * we can nullify the sigdeliver function pointer in the TCB and accept
+   * more signal deliveries while processing the current pending signals.
+   */
+
+  sigdeliver = rtcb->xcp.sigdeliver;
+  rtcb->xcp.sigdeliver = NULL;
+
+#  ifndef CONFIG_SUPPRESS_INTERRUPTS
+  /* Then make sure that interrupts are enabled.  Signal handlers must always
+   * run with interrupts enabled.
+   */
+
+  up_irq_enable();
+#  endif
+
+  /* Deliver the signals */
+
+  sigdeliver(rtcb);
+
+  /* Output any debug messages BEFORE restoring errno (because they may alter
+   * errno), then disable interrupts again and restore the original errno that
+   * is needed by the user logic (it is probably EINTR).
+   */
+
+  sinfo("Resuming EPC: %08x INT_CTX: %08x\n", regs[REG_CSR_MEPC],
+        regs[REG_CSR_MSTATUS]);
+
+  (void)up_irq_save();
+  rtcb->pterrno = saved_errno;
+
+  /* Then restore the correct state for this thread of execution. */
+
+  board_autoled_off(LED_SIGNAL);
+  up_fullcontextrestore(regs);
+
+  /* up_fullcontextrestore() should not return but could if the software
+   * interrupts are disabled.
+   */
+
+  DEBUGPANIC();
+}
+
+#endif  /* !CONFIG_DISABLE_SIGNALS */
@@ -0,0 +1,136 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_stackframe.c
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+
+#include "minerva.h"
+
+/****************************************************************************
+ * Pre-processor Macros
+ ****************************************************************************/
+
+/* MINERVA requires at least a 4-byte stack alignment.  For floating point
+ * use, however, the stack must be aligned to 8-byte addresses.
+ */
+
+#ifdef CONFIG_LIBC_FLOATINGPOINT
+#  define STACK_ALIGNMENT   8
+#else
+#  define STACK_ALIGNMENT   4
+#endif
+
+/* Stack alignment macros */
+
+#define STACK_ALIGN_MASK    (STACK_ALIGNMENT-1)
+#define STACK_ALIGN_DOWN(a) ((a) & ~STACK_ALIGN_MASK)
+#define STACK_ALIGN_UP(a)   (((a) + STACK_ALIGN_MASK) & ~STACK_ALIGN_MASK)
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_stack_frame
+ *
+ * Description:
+ *   Allocate a stack frame in the TCB's stack to hold thread-specific data.
+ *   This function may be called anytime after up_create_stack() or
+ *   up_use_stack() have been called but before the task has been started.
+ *
+ *   Thread data may be kept in the stack (instead of in the TCB) if it is
+ *   accessed by the user code directly.  This includes such things as
+ *   argv[].  The stack memory is guaranteed to be in the same protection
+ *   domain as the thread.
+ *
+ *   The following TCB fields will be re-initialized:
+ *
+ *   - adj_stack_size: Stack size after removal of the stack frame from
+ *     the stack
+ *   - adj_stack_ptr: Adjusted initial stack pointer after the frame has
+ *     been removed from the stack.  This will still be the initial value
+ *     of the stack pointer when the task is started.
+ *
+ * Input Parameters:
+ *   - tcb:  The TCB of new task
+ *   - frame_size:  The size of the stack frame to allocate.
+ *
+ *  Returned Value:
+ *   - A pointer to bottom of the allocated stack frame.  NULL will be
+ *     returned on any failures.  The alignment of the returned value is
+ *     the same as the alignment of the stack itself.
+ *
+ ****************************************************************************/
+
+FAR void *up_stack_frame(FAR struct tcb_s *tcb, size_t frame_size)
+{
+  uintptr_t topaddr;
+
+  /* Align the frame_size */
+
+  frame_size = STACK_ALIGN_UP(frame_size);
+
+  /* Is there already a stack allocated? Is it big enough? */
+
+  if (!tcb->stack_alloc_ptr || tcb->adj_stack_size <= frame_size)
+    {
+      return NULL;
+    }
+
+  /* Save the adjusted stack values in the struct tcb_s */
+
+  topaddr = (uintptr_t) tcb->adj_stack_ptr - frame_size;
+  tcb->adj_stack_ptr = (FAR void *)topaddr;
+  tcb->adj_stack_size -= frame_size;
+
+  /* Reset the initial stack pointer */
+
+  tcb->xcp.regs[REG_SP] = (uint32_t) tcb->adj_stack_ptr;
+
+  /* And return the pointer to the allocated region */
+
+  return (FAR void *)(topaddr + sizeof(uint32_t));
+}
@@ -0,0 +1,305 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_swint.c
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <string.h>
+#include <syscall.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/sched.h>
+#include <arch/irq.h>
+
+#include "minerva.h"
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_registerdump
+ ****************************************************************************/
+
+#ifdef CONFIG_DEBUG_SYSCALL_INFO
+static void up_registerdump(const uint32_t * regs)
+{
+#if 0
+  svcinfo("EPC:%08x\n", regs[REG_CSR_MEPC]);
+  svcinfo("A0:%08x A1:%08x A2:%08x A3:%08x A4:%08x A5:%08x A6:%08x A7:%08x\n",
+          regs[REG_A0], regs[REG_A1], regs[REG_A2], regs[REG_A3],
+          regs[REG_A4], regs[REG_A5], regs[REG_A6], regs[REG_A7]);
+  svcinfo("T0:%08x T1:%08x T2:%08x T3:%08x T4:%08x T5:%08x T6:%08x\n",
+          regs[REG_T0], regs[REG_T1], regs[REG_T2], regs[REG_T3],
+          regs[REG_T4], regs[REG_T5], regs[REG_T6]);
+  svcinfo("S0:%08x S1:%08x S2:%08x S3:%08x S4:%08x S5:%08x S6:%08x S7:%08x\n",
+          regs[REG_S0], regs[REG_S1], regs[REG_S2], regs[REG_S3],
+          regs[REG_S4], regs[REG_S5], regs[REG_S6], regs[REG_S7]);
+  svcinfo("S8:%08x S9:%08x S10:%08x S11:%08x\n",
+          regs[REG_S8], regs[REG_S9], regs[REG_S10], regs[REG_S11]);
+#ifdef MINERVA32_SAVE_GP
+  svcinfo("GP:%08x SP:%08x FP:%08x TP:%08x RA:%08x\n",
+          regs[REG_GP], regs[REG_SP], regs[REG_FP], regs[REG_TP], regs[REG_RA]);
+#else
+  svcinfo("SP:%08x FP:%08x TP:%08x RA:%08x\n",
+          regs[REG_SP], regs[REG_FP], regs[REG_TP], regs[REG_RA]);
+#endif
+#endif
+}
+#else
+#  define up_registerdump(regs)
+#endif
+
+/****************************************************************************
+ * Name: dispatch_syscall
+ *
+ * Description:
+ *   Call the stub function corresponding to the system call.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_BUILD_KERNEL
+static void dispatch_syscall(void) naked_function;
+     static void dispatch_syscall(void)
+{
+#error "Missing logic"
+
+/* Refer to arch/arm/src/armv7-m/up_svcall.h for how this is done for ARM */
+
+/* __asm__ __volatile__ */
+
+/* Save registers */
+
+/* Get the base of the stub lookup table */
+
+/* Get the offset of the stub for this syscall */
+
+/* Load the entry of the stub for this syscall */
+
+/* Call the stub */
+
+/* Restore regsisters */
+
+/* Return from the syscall */
+}
+#endif
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: minerva_swint
+ *
+ * Description:
+ *   This is software interrupt exception handler that performs context
+ *   switching and manages system calls
+ *
+ ****************************************************************************/
+
+int minerva_swint(int irq, FAR void *context, FAR void *arg)
+{
+  uint32_t *regs = (uint32_t *) context;
+
+  DEBUGASSERT(regs != NULL && regs == g_current_regs);
+
+  /* Software interrupt 0 is invoked with REG_A0 (REG_X10) = system call
+   * command and REG_A1-6 = variable number of arguments depending on the
+   * system call.
+   */
+
+#ifdef CONFIG_DEBUG_SYSCALL_INFO
+  svcinfo("Entry: regs: %p cmd: %d\n", regs, regs[REG_A0]);
+  up_registerdump(regs);
+#endif
+
+  /* Handle the SWInt according to the command in $a0 */
+
+  switch (regs[REG_A0])
+    {
+      /* A0=SYS_restore_context: This a restore context command: void
+       * up_fullcontextrestore(uint32_t *restoreregs) noreturn_function; At
+       * this point, the following values are saved in context: A0 =
+       * SYS_restore_context A1 = restoreregs In this case, we simply need to
+       * set g_current_regs to restore register area referenced in the saved
+       * R1. context == g_current_regs is the normal exception return.  By
+       * setting g_current_regs = context[R1], we force the return to the
+       * saved context referenced in $a1.
+       */
+
+    case SYS_restore_context:
+      {
+        DEBUGASSERT(regs[REG_A1] != 0);
+        g_current_regs = (uint32_t *) regs[REG_A1];
+      }
+      break;
+
+      /* A0=SYS_switch_context: This a switch context command: void
+       * up_switchcontext(uint32_t *saveregs, uint32_t *restoreregs); At this
+       * point, the following values are saved in context: A0 =
+       * SYS_switch_context A1 = saveregs A2 = restoreregs In this case, we
+       * save the context registers to the save register area reference by the
+       * saved contents of R5 and then set g_current_regs to to the save
+       * register area referenced by the saved contents of R6.
+       */
+
+    case SYS_switch_context:
+      {
+        DEBUGASSERT(regs[REG_A1] != 0 && regs[REG_A2] != 0);
+        minerva_copystate((uint32_t *) regs[REG_A1], regs);
+        g_current_regs = (uint32_t *) regs[REG_A2];
+      }
+      break;
+
+      /* A0=SYS_syscall_return: This a switch context command: void
+       * up_sycall_return(void); At this point, the following values are saved
+       * in context: A0 = SYS_syscall_return We need to restore the saved
+       * return address and return in unprivileged thread mode.
+       */
+
+#ifdef CONFIG_BUILD_KERNEL
+    case SYS_syscall_return:
+      {
+        struct tcb_s *rtcb = sched_self();
+        int index = (int)rtcb->xcp.nsyscalls - 1;
+
+        /* Make sure that there is a saved syscall return address. */
+
+        DEBUGASSERT(index >= 0);
+
+        /* Setup to return to the saved syscall return address in the original
+         * mode.
+         */
+
+        g_current_regs[REG_CSR_MEPC] = rtcb->xcp.syscall[index].sysreturn;
+#error "Missing logic -- need to restore the original mode"
+        rtcb->xcp.nsyscalls = index;
+      }
+      break;
+#endif
+
+      /* This is not an architecture-specify system call.  If NuttX is built
+       * as a standalone kernel with a system call interface, then all of the
+       * additional system calls must be handled as in the default case.
+       */
+
+    default:
+      {
+#ifdef CONFIG_BUILD_KERNEL
+        FAR struct tcb_s *rtcb = sched_self();
+        int index = rtcb->xcp.nsyscalls;
+
+        /* Verify that the SYS call number is within range */
+
+        DEBUGASSERT(g_current_regs[REG_A0] < SYS_maxsyscall);
+
+        /* Make sure that we got here that there is a no saved syscall return
+         * address.  We cannot yet handle nested system calls.
+         */
+
+        DEBUGASSERT(index < CONFIG_SYS_NNEST);
+
+        /* Setup to return to dispatch_syscall in privileged mode.
+        */
+
+        rtcb->xcpsyscall[index].sysreturn = regs[REG_CSR_MEPC];
+#error "Missing logic -- Need to save mode"
+        rtcb->xcp.nsyscalls = index + 1;
+
+        regs[REG_CSR_MEPC] = (uint32_t) dispatch_syscall;
+#error "Missing logic -- Need to set privileged mode"
+
+        /* Offset R0 to account for the reserved values */
+
+        g_current_regs[REG_A0] -= CONFIG_SYS_RESERVED;
+#else
+        svcerr("ERROR: Bad SYS call: %d\n", regs[REG_A0]);
+#endif
+      }
+      break;
+    }
+
+  /* Report what happened.  That might difficult in the case of a context
+   * switch
+   */
+
+#ifdef CONFIG_DEBUG_SYSCALL_INFO
+  if (regs != g_current_regs)
+    {
+      svcinfo("SWInt Return: Context switch!\n");
+      up_registerdump((const uint32_t *)g_current_regs);
+    }
+  else
+    {
+      svcinfo("SWInt Return: %d\n", regs[REG_A0]);
+    }
+#endif
+
+#if defined(CONFIG_ARCH_FPU) || defined(CONFIG_ARCH_ADDRENV)
+  /* Check for a context switch.  If a context switch occurred, then
+   * g_current_regs will have a different value than it did on entry.  If an
+   * interrupt level context switch has occurred, then restore the floating
+   * point state and the establish the correct address environment before
+   * returning from the interrupt.
+   */
+
+  if (regs != g_current_regs)
+    {
+#ifdef CONFIG_ARCH_FPU
+      /* Restore floating point registers */
+
+      up_restorefpu((uint32_t *) g_current_regs);
+#endif
+
+#ifdef CONFIG_ARCH_ADDRENV
+      /* Make sure that the address environment for the previously running
+       * task is closed down gracefully (data caches dump, MMU flushed) and
+       * set up the address environment for the new thread at the head of
+       * the ready-to-run list.
+       */
+
+      (void)group_addrenv(NULL);
+#endif
+    }
+#endif
+
+  return OK;
+}
@@ -0,0 +1,103 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_syscall.S
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Ramtin Amin <keytwo@gmail.com>
+ *
+ * Derives from RISC-V version:
+ *
+ *   Copyright (C) 2016 Ken Pettit. All rights reserved.
+ *   Author: Ken Pettit <pettitkd@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+/****************************************************************************
+ * Public Symbols
+ ****************************************************************************/
+
+	.file	"up_syscall.S"
+	.global sys_call0
+	.global sys_call1
+	.global sys_call2
+	.global sys_call3
+	.global sys_call4
+	.global sys_call5
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_syscall0, up_syscall1, up_syscall2, up_syscall3
+ *
+ * Description:
+ *   up_syscall0 - System call SYS_ argument and no additional parameters.
+ *   up_syscall1 - System call SYS_ argument and one additional parameter.
+ *   up_syscall2 - System call SYS_ argument and two additional parameters.
+ *   up_syscall3 - System call SYS_ argument and three additional parameters.
+ *   up_syscall4 - System call SYS_ argument and four additional parameters.
+ *   up_syscall5 - System call SYS_ argument and five additional parameters.
+ *
+ * Assumption:
+ *   All interrupts are disabled except for the software interrupts.
+ *
+ ****************************************************************************/
+
+	.text
+
+sys_call0:	/* a0 holds the syscall number */
+sys_call1:	/* a0 holds the syscall number, argument in a1 */
+sys_call2:	/* a0 holds the syscall number, arguments in a1 and a2 */
+sys_call3:	/* a0 holds the syscall number, arguments in a1, a2, and a3 */
+sys_call4:	/* a0 holds the syscall number, arguments in a1, a2, a3 and a4 */
+sys_call5:	/* a0 holds the syscall number, arguments in a1, a2, a3, a4 and a5 */
+
+	/* Issue the ECALL opcode to perform a SW interrupt to the OS */
+
+	ecall
+	
+	/* The actual interrupt may not a occur for a few more cycles.  Let's
+	 * put a few nop's here in hope that the SW interrupt occurs during
+	 * the sequence of nops.
+	 */
+
+	nop
+	nop
+
+	/* Then return with the result of the software interrupt in v0 */
+
+	ret
+	nop
@@ -0,0 +1,164 @@
+/****************************************************************************
+ *  arch/misoc/src/minerva/minerva_unblocktask.c
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *           Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sched.h>
+#include <syscall.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/sched.h>
+
+#include "sched/sched.h"
+#include "group/group.h"
+#include "clock/clock.h"
+#include "minerva.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_unblock_task
+ *
+ * Description:
+ *   A task is currently in an inactive task list
+ *   but has been prepped to execute.  Move the TCB to the
+ *   ready-to-run list, restore its context, and start execution.
+ *
+ * Input Parameters:
+ *   tcb: Refers to the tcb to be unblocked.  This tcb is
+ *     in one of the waiting tasks lists.  It must be moved to
+ *     the ready-to-run list and, if it is the highest priority
+ *     ready to run task, executed.
+ *
+ ****************************************************************************/
+
+void up_unblock_task(struct tcb_s *tcb)
+{
+  struct tcb_s *rtcb = this_task();
+
+  /* Verify that the context switch can be performed */
+
+  DEBUGASSERT((tcb->task_state >= FIRST_BLOCKED_STATE) &&
+              (tcb->task_state <= LAST_BLOCKED_STATE));
+
+  /* Remove the task from the blocked task list */
+
+  sched_removeblocked(tcb);
+
+  /* Add the task in the correct location in the prioritized ready-to-run task
+   * list
+   */
+
+  if (sched_addreadytorun(tcb))
+    {
+      /* The currently active task has changed! We need to do a context switch
+       * to the new task.
+       */
+
+      /* Update scheduler parameters */
+
+      sched_suspend_scheduler(rtcb);
+
+      /* Are we in an interrupt handler? */
+
+      if (g_current_regs)
+        {
+          /* Yes, then we have to do things differently. Just copy the
+           * g_current_regs into the OLD rtcb.
+           */
+
+          up_savestate(rtcb->xcp.regs);
+
+          /* Restore the exception context of the rtcb at the (new) head of
+           * the ready-to-run task list.
+           */
+
+          rtcb = this_task();
+
+          /* Update scheduler parameters */
+
+          sched_resume_scheduler(rtcb);
+
+          /* Then switch contexts.  Any necessary address environment changes
+           * will be made when the interrupt returns.
+           */
+
+          up_restorestate(rtcb->xcp.regs);
+        }
+
+      /* No, then we will need to perform the user context switch */
+
+      else
+        {
+          /* Restore the exception context of the new task that is ready to
+           * run (probably tcb).  This is the new rtcb at the head of the
+           * ready-to-run task list.
+           */
+
+          struct tcb_s *nexttcb = this_task();
+
+#ifdef CONFIG_ARCH_ADDRENV
+          /* Make sure that the address environment for the previously running
+           * task is closed down gracefully (data caches dump, MMU flushed)
+           * and set up the address environment for the new thread at the
+           * head of the ready-to-run list.
+           */
+
+          (void)group_addrenv(nexttcb);
+#endif
+          /* Update scheduler parameters */
+
+          sched_resume_scheduler(nexttcb);
+
+          /* Then switch contexts */
+
+          up_switchcontext(rtcb->xcp.regs, nexttcb->xcp.regs);
+
+          /* up_switchcontext forces a context switch to the task at the head
+           * of the ready-to-run list.  It does not 'return' in the normal
+           * sense.  When it does return, it is because the blocked task is
+           * again ready to run and has execution priority.
+           */
+        }
+    }
+}
@@ -0,0 +1,204 @@
+/****************************************************************************
+ * arch/misoc/src/minerva/minerva_vectors.S
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Ramtin Amin <keytwo@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <arch/irq.h>
+
+/****************************************************************************
+ * Pre-processor Defintions
+ ****************************************************************************/
+
+#define MINERVA_STACK_BASE    _ebss
+#define MINERVA_STACK_TOP     _ebss+CONFIG_IDLETHREAD_STACKSIZE
+#define MINERVA_HEAP_BASE     MINERVA_STACK_TOP
+
+#define MIE_MEIE              0x800
+#define CSR_IRQ_MASK          0x330
+
+/****************************************************************************
+ * Macros
+ ****************************************************************************/
+
+	.section	.text, "ax", @progbits
+	.global		g_idle_topstack
+	.global		__start
+
+.macro SAVE_REGS
+	addi sp, sp, -XCPTCONTEXT_SIZE
+	sw x0, REG_X0(sp)
+	sw x1, REG_X1(sp)
+	sw x3, REG_X3(sp)
+	sw x4, REG_X4(sp)
+	sw x5, REG_X5(sp)
+	sw x6, REG_X6(sp)
+	sw x7, REG_X7(sp)
+	sw x8, REG_X8(sp)
+	sw x9, REG_X9(sp)
+	sw x10, REG_X10(sp)
+	sw x11, REG_X11(sp)
+	sw x12, REG_X12(sp)
+	sw x13, REG_X13(sp)
+	sw x14, REG_X14(sp)
+	sw x15, REG_X15(sp)
+	sw x16, REG_X16(sp)
+	sw x17, REG_X17(sp)
+	sw x18, REG_X18(sp)
+	sw x19, REG_X19(sp)
+	sw x20, REG_X20(sp)
+	sw x21, REG_X21(sp)
+	sw x22, REG_X22(sp)
+	sw x23, REG_X23(sp)
+	sw x24, REG_X24(sp)
+	sw x25, REG_X25(sp)
+	sw x26, REG_X26(sp)
+	sw x27, REG_X27(sp)
+	sw x28, REG_X28(sp)
+	sw x29, REG_X29(sp)
+	sw x30, REG_X30(sp)
+	sw x31, REG_X31(sp)
+	csrr t0, mstatus
+	csrr t1, mepc
+	csrr t2, mbadaddr
+	csrr t3, mcause
+	sw t0, REG_CSR_MSTATUS(sp)
+	sw t1, REG_CSR_MEPC(sp)
+	sw t2, REG_CSR_MBADADDR(sp)
+	sw t3, REG_CSR_MCAUSE(sp)
+	addi t0, sp, XCPTCONTEXT_SIZE
+	sw t0, REG_X2(sp)
+ .endm
+
+/* restore regs and `mret` */
+
+ .macro RESTORE_REGS
+	lw x1, REG_X1(a0)
+	lw x2, REG_X2(a0)
+	lw x3, REG_X3(a0)
+	lw x4, REG_X4(a0)
+	lw x6, REG_X6(a0)
+	lw x7, REG_X7(a0)
+	lw x8, REG_X8(a0)
+	lw x9, REG_X9(a0)
+	lw x11, REG_X11(a0)
+	lw x12, REG_X12(a0)
+	lw x13, REG_X13(a0)
+	lw x14, REG_X14(a0)
+	lw x15, REG_X15(a0)
+	lw x16, REG_X16(a0)
+	lw x17, REG_X17(a0)
+	lw x18, REG_X18(a0)
+	lw x19, REG_X19(a0)
+	lw x20, REG_X20(a0)
+	lw x21, REG_X21(a0)
+	lw x22, REG_X22(a0)
+	lw x23, REG_X23(a0)
+	lw x24, REG_X24(a0)
+	lw x25, REG_X25(a0)
+	lw x26, REG_X26(a0)
+	lw x27, REG_X27(a0)
+	lw x28, REG_X28(a0)
+	lw x29, REG_X29(a0)
+	lw x30, REG_X30(a0)
+	lw x31, REG_X31(a0)
+
+	lw t0, REG_CSR_MEPC(a0)
+	csrw mepc, t0
+
+	lw t0, REG_CSR_MSTATUS(a0)
+	csrw mstatus, t0
+
+	lw x5, REG_X5(a0)
+	lw x10, REG_X10(a0)
+ .endm
+
+/****************************************************************************
+ * Reset Handler
+ ****************************************************************************/
+
+__start:
+_reset_handler:
+	/* Set stack pointer */
+
+	la sp, _fstack
+	la t0, trap_entry
+	csrw mtvec, t0
+
+	/* Initialize .bss */
+
+	la t0, _sbss
+	la t1, _ebss
+1:	beq t0, t1, 2f
+	sw zero, 0(t0)
+	addi t0, t0, 4
+	j 1b
+2:
+#if 0 /* REVISIT */
+	/* Enable external interrupts */
+
+	li t0, MIE_MEIE
+	csrs mie, t0
+#endif
+
+	call nx_start
+1:	j 1b
+
+trap_entry:
+	SAVE_REGS
+	mv a0, sp
+	call minerva_doexception
+	RESTORE_REGS
+	mret
+	nop
+	nop
+	nop
+	nop
+
+	/* This global variable is unsigned long g_idle_topstack and is
+	 * exported from here only because of its coupling to other
+	 * uses of _ebss in this file
+	 */
+
+	.data
+	.align  4
+	.type   g_idle_topstack, object
+
+g_idle_topstack:
+	.long	MINERVA_STACK_TOP
+	.size	g_idle_topstack, .-g_idle_topstack
+	.end
@@ -520,13 +520,19 @@ config ARCH_BOARD_MICROPENDOUS3
 		be populated with either an AVR AT90USB646, 647, 1286, or 1287 MCU.
 		Support is configured for the AT90USB647.

-config ARCH_BOARD_MISOC
+config ARCH_BOARD_MISOC_QEMU
 	bool "Qemu LM32 demo"
 	depends on ARCH_CHIP_LM32
 	---help---
 		This configuration is port to NuttX running on a Qemu LM32 system.
 		You can find the Qemu setup at https://bitbucket.org/key2/qemu

+config ARCH_BOARD_MISOC_VERILATOR
+	bool "Verilator Misoc demo"
+	depends on ARCH_CHIP_LM32 || ARCH_CHIP_MINERVA
+	---help---
+		This configuration is port to NuttX running on Verilator.
+
 config ARCH_BOARD_MOTEINO_MEGA
 	bool "LowPowerLab MoteinoMEGA"
 	depends on ARCH_CHIP_ATMEGA1284P
@@ -1823,7 +1829,7 @@ config ARCH_BOARD
 	default "metro-m4"                 if ARCH_BOARD_METRO_M4
 	default "micropendous3"            if ARCH_BOARD_MICROPENDOUS3
 	default "mirtoo"                   if ARCH_BOARD_MIRTOO
-	default "misoc"                    if ARCH_BOARD_MISOC
+	default "misoc"                    if ARCH_BOARD_MISOC_QEMU || ARCH_BOARD_MISOC_VERILATOR
 	default "moteino-mega"             if ARCH_BOARD_MOTEINO_MEGA
 	default "ne64badge"                if ARCH_BOARD_NE64BADGE
 	default "nrf52-generic"            if ARCH_BOARD_NRF52_GENERIC
@@ -2138,7 +2144,7 @@ endif
 if ARCH_BOARD_MIRTOO
 source "configs/mirtoo/Kconfig"
 endif
-if ARCH_BOARD_MISOC
+if ARCH_BOARD_MISOC_QEMU || ARCH_BOARD_MISOC_VERILATOR
 source "configs/misoc/Kconfig"
 endif
 if ARCH_BOARD_MOTEINO_MEGA
--- a/Show More
+++ b/Show More