Add support for Litex VexRiscV.

arch/risc-v/Kconfig

@@ -26,6 +26,12 @@ config ARCH_CHIP_K210
 	---help---
 		Kendryte K210 processor (RISC-V 64bit core with GC extensions)
 
+config ARCH_CHIP_LITEX
+	bool "Enjoy Digital LITEX VEXRISCV"
+	select ARCH_RV32IM
+	---help---
+		Enjoy Digital LITEX VEXRISCV softcore processor (RV32IMA).
+
 config ARCH_CHIP_NR5
 	bool "NEXT NanoRisc5"
 	select ARCH_RV32IM
@@ -62,6 +68,7 @@ config ARCH_CHIP
 	string
 	default "fe310"		if ARCH_CHIP_FE310
 	default "k210"		if ARCH_CHIP_K210
+	default "litex"		if ARCH_CHIP_LITEX
 	default "nr5m100"	if ARCH_CHIP_NR5
 	default "gap8"		if ARCH_CHIP_GAP8
 
@@ -87,6 +94,9 @@ endif
 if ARCH_CHIP_K210
 source arch/risc-v/src/k210/Kconfig
 endif
+if ARCH_CHIP_LITEX
+source arch/risc-v/src/litex/Kconfig
+endif
 if ARCH_CHIP_NR5
 source arch/risc-v/src/nr5m100/Kconfig
 endif

arch/risc-v/include/litex/chip.h

@@ -0,0 +1,24 @@
+/****************************************************************************
+ * arch/risc-v/include/litex/chip.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_RISCV_INCLUDE_LITEX_CHIP_H
+#define __ARCH_RISCV_INCLUDE_LITEX_CHIP_H
+
+#endif /* __ARCH_RISCV_INCLUDE_LITEX_CHIP_H */

arch/risc-v/include/litex/irq.h

@@ -0,0 +1,113 @@
+/****************************************************************************
+ * arch/risc-v/include/litex/irq.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_RISCV_INCLUDE_LITEX_IRQ_H
+#define __ARCH_RISCV_INCLUDE_LITEX_IRQ_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <arch/irq.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* In mstatus register */
+
+#define MSTATUS_MIE   (0x1 << 3)  /* Machine Interrupt Enable */
+#define MSTATUS_MPIE  (0x1 << 7)  /* Machine Previous Interrupt Enable */
+#define MSTATUS_MPPM  (0x3 << 11) /* Machine Previous Privilege (m-mode) */
+
+/* In mie (machine interrupt enable) register */
+
+#define MIE_MSIE      (0x1 << 3)  /* Machine Software Interrupt Enable */
+#define MIE_MTIE      (0x1 << 7)  /* Machine Timer Interrupt Enable */
+#define MIE_MEIE      (0x1 << 11) /* Machine External Interrupt Enable */
+#define MIP_MTIP (1 << 7)
+
+/* Map RISC-V exception code to NuttX IRQ */
+
+/* IRQ 0-15 : (exception:interrupt=0) */
+
+#define LITEX_IRQ_IAMISALIGNED  (0) /* Instruction Address Misaligned */
+#define LITEX_IRQ_IAFAULT       (1) /* Instruction Address Fault */
+#define LITEX_IRQ_IINSTRUCTION  (2) /* Illegal Instruction */
+#define LITEX_IRQ_BPOINT        (3) /* Break Point */
+#define LITEX_IRQ_LAMISALIGNED  (4) /* Load Address Misaligned */
+#define LITEX_IRQ_LAFAULT       (5) /* Load Access Fault */
+#define LITEX_IRQ_SAMISALIGNED  (6) /* Store/AMO Address Misaligned */
+#define LITEX_IRQ_SAFAULT       (7) /* Store/AMO Access Fault */
+#define LITEX_IRQ_ECALLU        (8) /* Environment Call from U-mode */
+                                    /* 9-10: Reserved */
+
+#define LITEX_IRQ_ECALLM       (11) /* Environment Call from M-mode */
+                                    /* 12-15: Reserved */
+
+/* IRQ 16- : (async event:interrupt=1) */
+
+#define LITEX_IRQ_ASYNC        (16)
+#define LITEX_IRQ_MSOFT    (LITEX_IRQ_ASYNC + 3)  /* Machine Software Int */
+#define LITEX_IRQ_MTIMER   (LITEX_IRQ_ASYNC + 7)  /* Machine Timer Int */
+#define LITEX_IRQ_MEXT     (LITEX_IRQ_ASYNC + 11) /* Machine External Int */
+
+/* Machine Global External Interrupt */
+
+#define LITEX_IRQ_UART0    (LITEX_IRQ_MEXT + 1)
+#define LITEX_IRQ_TIMER0   (LITEX_IRQ_MEXT + 2)
+
+/* Total number of IRQs */
+
+#define NR_IRQS            (LITEX_IRQ_TIMER0 + 1)
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+#undef EXTERN
+#if defined(__cplusplus)
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+EXTERN irqstate_t  up_irq_save(void);
+EXTERN void up_irq_restore(irqstate_t);
+EXTERN irqstate_t up_irq_enable(void);
+
+#undef EXTERN
+#if defined(__cplusplus)
+}
+#endif
+#endif /* __ASSEMBLY__ */
+#endif /* __ARCH_RISCV_INCLUDE_LITEX_IRQ_H */

arch/risc-v/src/litex/Kconfig

@@ -0,0 +1,28 @@
+#
+# For a description of the syntax of this configuration file,
+# see the file kconfig-language.txt in the NuttX tools repository.
+#
+
+comment "LITEX Configuration Options"
+
+menu "LITEX Peripheral Support"
+
+# These "hidden" settings determine is a peripheral option is available for the
+# selection MCU
+
+config LITEX_HAVE_UART0
+	bool
+	default y
+	select UART0_SERIALDRIVER
+	select ARCH_HAVE_SERIAL_TERMIOS
+
+# These are the peripheral selections proper
+
+config LITEX_UART0
+	bool "UART0"
+	default y
+	select ARCH_HAVE_UART0
+	select ARCH_HAVE_SERIAL_TERMIOS
+	select LITEX_UART
+
+endmenu

arch/risc-v/src/litex/Make.defs

@@ -0,0 +1,49 @@
+############################################################################
+# arch/risc-v/src/litex/Make.defs
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.  The
+# ASF licenses this file to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance with the
+# License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+############################################################################
+
+# Specify our HEAD assembly file.  This will be linked as
+# the first object file, so it will appear at address 0
+HEAD_ASRC = litex_vectors.S
+
+# Specify our general Assembly files
+CHIP_ASRCS = litex_head.S up_syscall.S
+
+# Specify C code within the common directory to be included
+CMN_CSRCS  += up_initialize.c up_swint.c
+CMN_CSRCS  += up_allocateheap.c up_createstack.c up_exit.c
+CMN_CSRCS  += up_assert.c up_blocktask.c up_copystate.c up_initialstate.c
+CMN_CSRCS  += up_interruptcontext.c up_modifyreg32.c up_puts.c up_mdelay.c
+CMN_CSRCS  += up_releasepending.c up_reprioritizertr.c
+CMN_CSRCS  += up_releasestack.c up_stackframe.c up_schedulesigaction.c
+CMN_CSRCS  += up_sigdeliver.c up_udelay.c up_unblocktask.c up_usestack.c
+
+ifeq ($(CONFIG_STACK_COLORATION),y)
+CMN_CSRCS += up_checkstack.c
+endif
+
+ifeq ($(CONFIG_ARCH_HAVE_VFORK),y)
+CMN_CSRCS  += up_vfork.c
+endif
+
+# Specify our C code within this directory to be included
+CHIP_CSRCS  = litex_allocateheap.c litex_clockconfig.c
+CHIP_CSRCS += litex_idle.c litex_irq.c litex_irq_dispatch.c
+CHIP_CSRCS += litex_lowputc.c litex_serial.c
+CHIP_CSRCS += litex_start.c litex_timerisr.c

arch/risc-v/src/litex/chip.h

@@ -0,0 +1,32 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/chip.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_RISCV_SRC_LITEX_CHIP_H
+#define __ARCH_RISCV_SRC_LITEX_CHIP_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include "litex_memorymap.h"
+
+#endif /* __ARCH_RISCV_SRC_LITEX_CHIP_H */

arch/risc-v/src/litex/hardware/litex_clint.h

@@ -0,0 +1,32 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/hardware/litex_clint.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_RISCV_SRC_LITEX_HARDWARE_LITEX_CLINT_H
+#define __ARCH_RISCV_SRC_LITEX_HARDWARE_LITEX_CLINT_H
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define LITEX_CLINT_LATCH      (LITEX_CPUTIMER_BASE)
+#define LITEX_CLINT_MTIME      (LITEX_CPUTIMER_BASE + 0x04)
+#define LITEX_CLINT_MTIMECMP   (LITEX_CPUTIMER_BASE + 0x24)
+
+#endif /* __ARCH_RISCV_SRC_LITEX_HARDWARE_LITEX_CLINT_H */

arch/risc-v/src/litex/hardware/litex_memorymap.h

@@ -0,0 +1,38 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/hardware/litex_memorymap.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_RISCV_SRC_LITEX_HARDWARE_LITEX_MEMORYMAP_H
+#define __ARCH_RISCV_SRC_LITEX_HARDWARE_LITEX_MEMORYMAP_H
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* Register Base Address ****************************************************/
+
+/* litex vexRiscv does not follow RISC-V privileged specification and
+ * uses two additional CSRs: mask and pending.
+ */
+
+#define LITEX_CPUTIMER_BASE 0xf0000800  /* riscv clint timer */
+#define LITEX_TIMER0_BASE   0xf0001800
+#define LITEX_UART0_BASE    0xf0001000  /* 0xf0001000 - : UART0 */
+
+#endif /* __ARCH_RISCV_SRC_LITEX_HARDWARE_LITEX_MEMORYMAP_H */

arch/risc-v/src/litex/hardware/litex_plic.h

@@ -0,0 +1,34 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/hardware/litex_plic.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_RISCV_SRC_LITEX_HARDWARE_LITEX_PLIC_H
+#define __ARCH_RISCV_SRC_LITEX_HARDWARE_LITEX_PLIC_H
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* litex vexRiscv does not follow RISC-V privileged specification and
+ * uses two additional CSRs: mask and pending.
+ */
+#define LITEX_MMASK_CSR     0xBC0
+#define LITEX_MPENDING_CSR     0xFC0
+
+#endif /* __ARCH_RISCV_SRC_LITEX_HARDWARE_LITEX_PLIC_H */

arch/risc-v/src/litex/hardware/litex_uart.h

@@ -0,0 +1,48 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/hardware/litex_uart.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef ARCH_RISCV_SRC_LITEX_CHIP_LITEX_UART_H
+#define ARCH_RISCV_SRC_LITEX_CHIP_LITEX_UART_H
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define UART_RXTX_OFFSET        0x00
+#define UART_TXFULL_OFFSET      0x04
+#define UART_RXEMPTY_OFFSET     0x08
+#define UART_EV_STATUS_OFFSET   0x0c
+#define UART_EV_PENDING_OFFSET  0x10
+#define UART_EV_ENABLE_OFFSET   0x14
+
+#ifdef CONFIG_LITEX_UART0
+#  define LITEX_UART0_RXTX          (LITEX_UART0_BASE + UART_RXTX_OFFSET)
+#  define LITEX_UART0_TXFULL        (LITEX_UART0_BASE + UART_TXFULL_OFFSET)
+#  define LITEX_UART0_RXEMPTY       (LITEX_UART0_BASE + UART_RXEMPTY_OFFSET)
+#  define LITEX_UART0_EV_STATUS     (LITEX_UART0_BASE + UART_EV_STATUS_OFFSET)
+#  define LITEX_UART0_EV_PENDING    (LITEX_UART0_BASE + UART_EV_PENDING_OFFSET)
+#  define LITEX_UART0_EV_ENABLE     (LITEX_UART0_BASE + UART_EV_ENABLE_OFFSET)
+#  define LITEX_UART0_PHY_TUNING_WORD   0xf0002000L
+#endif
+
+#define UART_EV_TX	0x1
+#define UART_EV_RX	0x2
+
+#endif /* _ARCH_RISCV_SRC_LITEX_CHIP_LITEX_UART_H */

arch/risc-v/src/litex/litex.h

@@ -0,0 +1,38 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_RISCV_SRC_LITEX_LITEX_H
+#define __ARCH_RISCV_SRC_LITEX_LITEX_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#include <arch/irq.h>
+#include "up_internal.h"
+#include "chip.h"
+#include "litex_lowputc.h"
+
+#endif /* __ARCH_RISCV_SRC_LITEX_LITEX_H */

arch/risc-v/src/litex/litex_allocateheap.c

@@ -0,0 +1,41 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex_allocateheap.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <arch/board/board.h>
+
+#include "litex.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_addregion
+ ****************************************************************************/
+
+void up_addregion(void)
+{
+}

arch/risc-v/src/litex/litex_clockconfig.c

@@ -0,0 +1,63 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex_clockconfig.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <arch/board/board.h>
+
+#include "up_arch.h"
+#include "litex_clockconfig.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: litex_get_hfclk
+ ****************************************************************************/
+
+uint32_t litex_get_hfclk(void)
+{
+  /* fpga fabric default sys frequency */
+
+  return 100000000UL;
+}
+
+/****************************************************************************
+ * Name: litex_clockconfig
+ ****************************************************************************/
+
+void litex_clockconfig(void)
+{
+  /* pll is set by fpga fabric */
+}

arch/risc-v/src/litex/litex_clockconfig.h

@@ -0,0 +1,65 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex_clockconfig.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_RISCV_SRC_LITEX_LITEX_CLOCKCONFIG_H
+#define __ARCH_RISCV_SRC_LITEX_LITEX_CLOCKCONFIG_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include "litex_memorymap.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+EXTERN uint32_t litex_get_hfclk(void);
+EXTERN void litex_clockconfig(void);
+
+#if defined(__cplusplus)
+}
+#endif
+#undef EXTERN
+
+#endif /* __ASSEMBLY__ */
+#endif /* __ARCH_RISCV_SRC_LITEX_LITEX_CLOCKCONFIG_H */

arch/risc-v/src/litex/litex_config.h

@@ -0,0 +1,54 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex_config.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_RISCV_SRC_LITEX_LITEX_CONFIG_H
+#define __ARCH_RISCV_SRC_LITEX_LITEX_CONFIG_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <arch/chip/chip.h>
+#include <arch/board/board.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#undef HAVE_UART_DEVICE
+#if defined(CONFIG_LITEX_UART0) || defined(CONFIG_LITEX_UART1)
+#  define HAVE_UART_DEVICE 1
+#endif
+
+#if defined(CONFIG_UART0_SERIAL_CONSOLE) && defined(CONFIG_LITEX_UART0)
+#  undef CONFIG_UART1_SERIAL_CONSOLE
+#  define HAVE_SERIAL_CONSOLE 1
+#elif defined(CONFIG_UART1_SERIAL_CONSOLE) && defined(CONFIG_LITEX_UART1)
+#  undef CONFIG_UART0_SERIAL_CONSOLE
+#  define HAVE_SERIAL_CONSOLE 1
+#else
+#  undef CONFIG_UART0_SERIAL_CONSOLE
+#  undef CONFIG_UART1_SERIAL_CONSOLE
+#  undef HAVE_SERIAL_CONSOLE
+#endif
+
+#endif /* __ARCH_RISCV_SRC_LITEX_LITEX_CONFIG_H */

arch/risc-v/src/litex/litex_head.S

@@ -0,0 +1,204 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex_head.S
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <arch/rv32im/irq.h>
+
+#include "chip.h"
+
+/****************************************************************************
+ * Public Symbols
+ ****************************************************************************/
+
+  .global exception_common
+
+  /* Imported symbols */
+
+  .extern __trap_vec
+
+  .section .text
+  .global __start
+
+__start:
+
+  /* Set stack pointer to the idle thread stack */
+
+  lui  sp, %hi(LITEX_IDLESTACK_TOP)
+  addi sp, sp, %lo(LITEX_IDLESTACK_TOP)
+
+  /* Disable all interrupts (i.e. timer, external) in mie */
+
+  csrw mie, zero
+
+  /* Initialize the Machine Trap Vector */
+
+  lui  t0, %hi(__trap_vec)
+  addi t0, t0, %lo(__trap_vec)
+  csrw  mtvec, t0
+
+  /* Jump to __litex_start */
+
+  jal  x1, __litex_start
+
+  /* We shouldn't return from __litex_start */
+
+  .global _init
+  .global _fini
+
+_init:
+_fini:
+
+  /* These don't have to do anything since we use init_array/fini_array. */
+
+  ret
+
+/****************************************************************************
+ * Name: exception_common
+ ****************************************************************************/
+
+exception_common:
+
+  addi sp, sp, -XCPTCONTEXT_SIZE
+
+  sw   x1,  1*4(sp)  /* ra */
+  sw   x3,  3*4(sp)  /* gp */
+  sw   x4,  4*4(sp)  /* tp */
+  sw   x5,  5*4(sp)  /* t0 */
+  sw   x6,  6*4(sp)  /* t1 */
+  sw   x7,  7*4(sp)  /* t2 */
+  sw   x8,  8*4(sp)  /* s0 */
+  sw   x9,  9*4(sp)  /* s1 */
+  sw   x10, 10*4(sp) /* a0 */
+  sw   x11, 11*4(sp) /* a1 */
+  sw   x12, 12*4(sp) /* a2 */
+  sw   x13, 13*4(sp) /* a3 */
+  sw   x14, 14*4(sp) /* a4 */
+  sw   x15, 15*4(sp) /* a5 */
+  sw   x16, 16*4(sp) /* a6 */
+  sw   x17, 17*4(sp)  /* a7 */
+  sw   x18, 18*4(sp)  /* s2 */
+  sw   x19, 19*4(sp)  /* s3 */
+  sw   x20, 20*4(sp)  /* s4 */
+  sw   x21, 21*4(sp)  /* s5 */
+  sw   x22, 22*4(sp)  /* s6 */
+  sw   x23, 23*4(sp)  /* s7 */
+  sw   x24, 24*4(sp)  /* s8 */
+  sw   x25, 25*4(sp)  /* s9 */
+  sw   x26, 26*4(sp)  /* s10 */
+  sw   x27, 27*4(sp)  /* s11 */
+  sw   x28, 28*4(sp)  /* t3 */
+  sw   x29, 29*4(sp)  /* t4 */
+  sw   x30, 30*4(sp)  /* t5 */
+  sw   x31, 31*4(sp)  /* t6 */
+
+  csrr s0, mstatus
+  sw   s0,  32*4(sp)  /* mstatus */
+
+  addi s0, sp, XCPTCONTEXT_SIZE
+  sw   s0,  2*4(sp)   /* original SP */
+
+  /* Setup arg0(exception cause), arg1(context) */
+
+  csrr a0, mcause  /* exception cause */
+  csrr s0, mepc
+  sw   s0, 0(sp)   /* exception PC */
+
+  mv   a1, sp      /* context = sp */
+
+#if CONFIG_ARCH_INTERRUPTSTACK > 3
+  /* Switch to interrupt stack */
+
+  lui  sp, %hi(g_intstackbase)
+  addi sp, sp, %lo(g_intstackbase)
+#endif
+
+  /* Call interrupt handler in C */
+
+  jal  x1, litex_dispatch_irq
+
+  /* If context switch is needed, return a new sp */
+
+  mv   sp, a0
+  lw   s0, 0(sp)    /* restore mepc */
+  csrw mepc, s0
+
+  lw   s0, 32*4(sp) /* restore mstatus */
+  csrw mstatus, s0
+
+  lw  x3,  3*4(sp)  /* gp */
+  lw  x4,  4*4(sp)  /* tp */
+  lw  x5,  5*4(sp)  /* t0 */
+  lw  x6,  6*4(sp)  /* t1 */
+  lw  x7,  7*4(sp)  /* t2 */
+  lw  x8,  8*4(sp)  /* s0 */
+  lw  x9,  9*4(sp)  /* s1 */
+  lw x10, 10*4(sp)  /* a0 */
+  lw x11, 11*4(sp)  /* a1 */
+  lw x12, 12*4(sp)  /* a2 */
+  lw x13, 13*4(sp)  /* a3 */
+  lw x14, 14*4(sp)  /* a4 */
+  lw x15, 15*4(sp)  /* a5 */
+  lw x16, 16*4(sp)  /* a6 */
+  lw x17, 17*4(sp)  /* a7 */
+  lw x18, 18*4(sp)  /* s2 */
+  lw x19, 19*4(sp)  /* s3 */
+  lw x20, 20*4(sp)  /* s4 */
+  lw x21, 21*4(sp)  /* s5 */
+  lw x22, 22*4(sp)  /* s6 */
+  lw x23, 23*4(sp)  /* s7 */
+  lw x24, 24*4(sp)  /* s8 */
+  lw x25, 25*4(sp)  /* s9 */
+  lw x26, 26*4(sp)  /* s10 */
+  lw x27, 27*4(sp)  /* s11 */
+  lw x28, 28*4(sp)  /* t3 */
+  lw x29, 29*4(sp)  /* t4 */
+  lw x30, 30*4(sp)  /* t5 */
+  lw x31, 31*4(sp)  /* t6 */
+
+  lw  x1,  1*4(sp)  /* ra */
+
+  lw  sp,  2*4(sp)  /* restore original sp */
+
+  /* Return from Machine Interrupt */
+
+  mret
+
+/************************************************************************************
+ *  Name: g_intstackalloc and g_intstackbase
+ ************************************************************************************/
+
+#if CONFIG_ARCH_INTERRUPTSTACK > 3
+  .bss
+  .align  4
+  .global g_intstackalloc
+  .global g_intstackbase
+  .type   g_intstackalloc, object
+  .type   g_intstackbase, object
+g_intstackalloc:
+  .skip  ((CONFIG_ARCH_INTERRUPTSTACK & ~3))
+g_intstackbase:
+  .skip  4
+  .size  g_intstackbase, 4
+  .size  g_intstackalloc, (CONFIG_ARCH_INTERRUPTSTACK & ~3)
+#endif

arch/risc-v/src/litex/litex_idle.c

@@ -0,0 +1,67 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex_idle.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <nuttx/board.h>
+#include <arch/board/board.h>
+
+#include "up_internal.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.
+   */
+
+  nxsched_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
+   */
+
+  asm("WFI");
+
+#endif
+}

arch/risc-v/src/litex/litex_irq.c

@@ -0,0 +1,263 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex_irq.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <stdio.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/board.h>
+#include <arch/irq.h>
+#include <arch/board/board.h>
+
+#include "up_internal.h"
+#include "up_arch.h"
+
+#include "litex.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_irqinitialize
+ ****************************************************************************/
+
+void up_irqinitialize(void)
+{
+  /* Disable Machine interrupts */
+
+  up_irq_save();
+
+  /* Disable all global interrupts */
+
+  asm volatile ("csrw %0, %1" :: "i"(LITEX_MMASK_CSR), "r"(0));
+
+  /* Colorize the interrupt stack for debug purposes */
+
+#if defined(CONFIG_STACK_COLORATION) && CONFIG_ARCH_INTERRUPTSTACK > 3
+  size_t intstack_size = (CONFIG_ARCH_INTERRUPTSTACK & ~3);
+  up_stack_color((FAR void *)((uintptr_t)&g_intstackbase - intstack_size),
+                 intstack_size);
+#endif
+
+  /* litex vexriscv dont have priority and threshold control */
+
+  /* currents_regs is non-NULL only while processing an interrupt */
+
+  g_current_regs = NULL;
+
+  /* Attach the ecall interrupt handler */
+
+  irq_attach(LITEX_IRQ_ECALLM, up_swint, NULL);
+
+#ifndef CONFIG_SUPPRESS_INTERRUPTS
+
+  /* And finally, enable interrupts */
+
+  up_irq_enable();
+#endif
+}
+
+/****************************************************************************
+ * Name: up_disable_irq
+ *
+ * Description:
+ *   Disable the IRQ specified by 'irq'
+ *
+ ****************************************************************************/
+
+void up_disable_irq(int irq)
+{
+  int extirq;
+  int mask;
+  uint32_t oldstat;
+
+  if (irq == LITEX_IRQ_MSOFT)
+    {
+      /* Read mstatus & clear machine software interrupt enable in mie */
+
+      asm volatile ("csrrc %0, mie, %1": "=r" (oldstat) : "r"(MIE_MSIE));
+    }
+  else if (irq == LITEX_IRQ_MTIMER)
+    {
+      /* Read mstatus & clear machine timer interrupt enable in mie */
+
+      asm volatile ("csrrc %0, mie, %1": "=r" (oldstat) : "r"(MIE_MTIE));
+    }
+  else if (irq > LITEX_IRQ_MEXT)
+    {
+      extirq = irq - LITEX_IRQ_MEXT;
+      extirq--;
+
+      /* Clear enable bit for the irq */
+
+      if (0 <= extirq && extirq <= 31)
+        {
+          asm volatile ("csrr %0, %1" : "=r"(mask) : "i"(LITEX_MMASK_CSR));
+          mask &= ~(1 << extirq);
+          asm volatile ("csrw %0, %1" :: "i"(LITEX_MMASK_CSR), "r"(mask));
+        }
+      else
+        {
+          ASSERT(false);
+        }
+    }
+}
+
+/****************************************************************************
+ * Name: up_enable_irq
+ *
+ * Description:
+ *   Enable the IRQ specified by 'irq'
+ *
+ ****************************************************************************/
+
+void up_enable_irq(int irq)
+{
+  int extirq;
+  int mask;
+  uint32_t oldstat;
+
+  if (irq == LITEX_IRQ_MSOFT)
+    {
+      /* Read mstatus & set machine software interrupt enable in mie */
+
+      asm volatile ("csrrs %0, mie, %1": "=r" (oldstat) : "r"(MIE_MSIE));
+    }
+  else if (irq == LITEX_IRQ_MTIMER)
+    {
+      /* Read mstatus & set machine timer interrupt enable in mie */
+
+      asm volatile ("csrrs %0, mie, %1": "=r" (oldstat) : "r"(MIE_MTIE));
+    }
+  else if (irq > LITEX_IRQ_MEXT)
+    {
+      extirq = irq - LITEX_IRQ_MEXT;
+      extirq--;
+
+      /* Set enable bit for the irq */
+
+      if (0 <= extirq && extirq <= 31)
+        {
+          asm volatile ("csrr %0, %1" : "=r"(mask) : "i"(LITEX_MMASK_CSR));
+          mask |= (1 << extirq);
+          asm volatile ("csrw %0, %1" :: "i"(LITEX_MMASK_CSR), "r"(mask));
+        }
+      else
+        {
+          ASSERT(false);
+        }
+    }
+}
+
+/****************************************************************************
+ * Name: up_get_newintctx
+ *
+ * Description:
+ *   Return initial mstatus when a task is created.
+ *
+ ****************************************************************************/
+
+uint32_t up_get_newintctx(void)
+{
+  /* Set machine previous privilege mode to machine mode.
+   * Also set machine previous interrupt enable
+   */
+
+  return (MSTATUS_MPPM | MSTATUS_MPIE);
+}
+
+/****************************************************************************
+ * Name: up_ack_irq
+ *
+ * Description:
+ *   Acknowledge the IRQ
+ *
+ ****************************************************************************/
+
+void up_ack_irq(int irq)
+{
+}
+
+/****************************************************************************
+ * Name: up_irq_save
+ *
+ * Description:
+ *   Return the current interrupt state and disable interrupts
+ *
+ ****************************************************************************/
+
+irqstate_t up_irq_save(void)
+{
+  uint32_t oldstat;
+
+  /* Read mstatus & clear machine interrupt enable (MIE) in mstatus */
+
+  asm volatile ("csrrc %0, mstatus, %1": "=r" (oldstat) : "r"(MSTATUS_MIE));
+  return oldstat;
+}
+
+/****************************************************************************
+ * Name: up_irq_restore
+ *
+ * Description:
+ *   Restore previous IRQ mask state
+ *
+ ****************************************************************************/
+
+void up_irq_restore(irqstate_t flags)
+{
+  /* Write flags to mstatus */
+
+  asm volatile("csrw mstatus, %0" : /* no output */ : "r" (flags));
+}
+
+/****************************************************************************
+ * Name: up_irq_enable
+ *
+ * Description:
+ *   Return the current interrupt state and enable interrupts
+ *
+ ****************************************************************************/
+
+irqstate_t up_irq_enable(void)
+{
+  uint32_t oldstat;
+
+#if 1
+  /* Enable MEIE (machine external interrupt enable) */
+
+  /* TODO: should move to up_enable_irq() */
+
+  asm volatile ("csrrs %0, mie, %1": "=r" (oldstat) : "r"(MIE_MEIE));
+#endif
+
+  /* Read mstatus & set machine interrupt enable (MIE) in mstatus */
+
+  asm volatile ("csrrs %0, mstatus, %1": "=r" (oldstat) : "r"(MSTATUS_MIE));
+  return oldstat;
+}

arch/risc-v/src/litex/litex_irq_dispatch.c

@@ -0,0 +1,126 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex_irq_dispatch.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <assert.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <nuttx/board.h>
+#include <arch/board/board.h>
+
+#include "up_arch.h"
+#include "up_internal.h"
+
+#include "litex.h"
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+volatile uint32_t * g_current_regs;
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * litex_dispatch_irq
+ ****************************************************************************/
+
+void *litex_dispatch_irq(uint32_t vector, uint32_t *regs)
+{
+  uint32_t  irq = (vector >> 27) | (vector & 0xf);
+  uint32_t *mepc = regs;
+  int i;
+
+  /* Firstly, check if the irq is machine external interrupt */
+
+  if (LITEX_IRQ_MEXT == irq)
+    {
+      /* litex vexriscv dont follow riscv plic standard */
+
+      unsigned int pending;
+      unsigned int mask;
+      asm volatile ("csrr %0, %1" : "=r"(pending) : "i"(LITEX_MPENDING_CSR));
+      asm volatile ("csrr %0, %1" : "=r"(mask) : "i"(LITEX_MMASK_CSR));
+
+      uint32_t val = (pending & mask);
+      for (i = 0; i < 32; i++)
+        {
+          if (val & (1 << i))
+            {
+              val = i;
+              val++;
+              break;
+            }
+        }
+
+      /* Add the value to nuttx irq which is offset to the mext */
+
+      irq += val;
+    }
+
+  /* NOTE: In case of ecall, we need to adjust mepc in the context */
+
+  if (LITEX_IRQ_ECALLM == irq)
+    {
+      *mepc += 4;
+    }
+
+  /* Acknowledge the interrupt */
+
+  up_ack_irq(irq);
+
+#ifdef CONFIG_SUPPRESS_INTERRUPTS
+  PANIC();
+#else
+  /* 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;
+
+  /* Deliver the IRQ */
+
+  irq_dispatch(irq, regs);
+
+#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;
+  g_current_regs = NULL;
+
+  return regs;
+}

arch/risc-v/src/litex/litex_lowputc.c

@@ -0,0 +1,124 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex_lowputc.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+
+#include <arch/board/board.h>
+
+#include "up_internal.h"
+#include "up_arch.h"
+
+#include "litex_config.h"
+#include "hardware/litex_memorymap.h"
+#include "hardware/litex_uart.h"
+#include "litex_clockconfig.h"
+#include "litex.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* Select UART parameters for the selected console */
+
+#ifdef HAVE_SERIAL_CONSOLE
+#  if defined(CONFIG_UART0_SERIAL_CONSOLE)
+#    define LITEX_CONSOLE_BASE        LITEX_UART0_BASE
+#    define LITEX_CONSOLE_BAUD        CONFIG_UART0_BAUD
+#    define LITEX_CONSOLE_BITS        CONFIG_UART0_BITS
+#    define LITEX_CONSOLE_PARITY      CONFIG_UART0_PARITY
+#    define LITEX_CONSOLE_2STOP       CONFIG_UART0_2STOP
+#    define LITEX_CONSOLE_TX          GPIO_UART0_TX
+#    define LITEX_CONSOLE_RX          GPIO_UART0_RX
+#    define HAVE_UART
+#  elif defined(CONFIG_UART1_SERIAL_CONSOLE)
+#    define LITEX_CONSOLE_BASE        LITEX_UART1_BASE
+#    define LITEX_CONSOLE_BAUD        CONFIG_UART1_BAUD
+#    define LITEX_CONSOLE_BITS        CONFIG_UART1_BITS
+#    define LITEX_CONSOLE_PARITY      CONFIG_UART1_PARITY
+#    define LITEX_CONSOLE_2STOP       CONFIG_UART1_2STOP
+#    define LITEX_CONSOLE_TX          GPIO_UART1_TX
+#    define LITEX_CONSOLE_RX          GPIO_UART1_RX
+#    define HAVE_UART
+#  endif
+#endif /* HAVE_CONSOLE */
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_lowputc
+ *
+ * Description:
+ *   Output one byte on the serial console
+ *
+ ****************************************************************************/
+
+void up_lowputc(char ch)
+{
+#ifdef HAVE_SERIAL_CONSOLE
+  /* Wait until the TX data register is empty */
+
+  while (getreg8(LITEX_CONSOLE_BASE + UART_TXFULL_OFFSET))
+    ;
+
+  /* Then send the character */
+
+  putreg8(ch, LITEX_CONSOLE_BASE + UART_RXTX_OFFSET);
+  putreg8(UART_EV_TX, LITEX_CONSOLE_BASE + UART_EV_PENDING_OFFSET);
+
+#endif /* HAVE_CONSOLE */
+}
+
+/****************************************************************************
+ * Name: litex_lowsetup
+ *
+ * Description:
+ *   This performs basic initialization of the UART used for the serial
+ *   console.  Its purpose is to get the console output available as soon
+ *   as possible.
+ *
+ ****************************************************************************/
+
+void litex_lowsetup(void)
+{
+#if defined(HAVE_UART)
+
+  /* Enable and configure the selected console device */
+
+#if defined(HAVE_SERIAL_CONSOLE) && !defined(CONFIG_SUPPRESS_UART_CONFIG)
+
+  /* defualt baudrate set by fpga fabric is 1e6 */
+
+  /* Enable TX */
+
+  putreg8(getreg8(LITEX_CONSOLE_BASE + UART_EV_PENDING_OFFSET),         \
+                            LITEX_CONSOLE_BASE + UART_EV_PENDING_OFFSET);
+  putreg8(UART_EV_TX, LITEX_CONSOLE_BASE + UART_EV_ENABLE_OFFSET);
+
+#endif /* HAVE_SERIAL_CONSOLE && !CONFIG_SUPPRESS_UART_CONFIG */
+#endif /* HAVE_UART */
+}

arch/risc-v/src/litex/litex_lowputc.h

@@ -0,0 +1,59 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex_lowputc.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_RISCV_SRC_LITEX_LITEX_LOWPUTC_H
+#define __ARCH_RISCV_SRC_LITEX_LITEX_LOWPUTC_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include "chip.h"
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+
+#undef EXTERN
+#if defined(__cplusplus)
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Name: litex_lowsetup
+ ****************************************************************************/
+
+EXTERN void litex_lowsetup(void);
+
+#undef EXTERN
+#if defined(__cplusplus)
+}
+#endif
+
+#endif /* __ASSEMBLY__ */
+#endif /* __ARCH_RISCV_SRC_LITEX_LITEX_LOWPUTC_H */

arch/risc-v/src/litex/litex_memorymap.h

@@ -0,0 +1,48 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex_memorymap.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef _ARCH_RISCV_SRC_LITEX_LITEX_MEMORYMAP_H
+#define _ARCH_RISCV_SRC_LITEX_LITEX_MEMORYMAP_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include "hardware/litex_memorymap.h"
+#include "hardware/litex_uart.h"
+#include "hardware/litex_clint.h"
+#include "hardware/litex_plic.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* Idle thread stack starts from _ebss */
+
+#ifndef __ASSEMBLY__
+#define LITEX_IDLESTACK_BASE  (uint32_t)&_ebss
+#else
+#define LITEX_IDLESTACK_BASE  _ebss
+#endif
+
+#define LITEX_IDLESTACK_SIZE (CONFIG_IDLETHREAD_STACKSIZE & ~3)
+#define LITEX_IDLESTACK_TOP  (LITEX_IDLESTACK_BASE + LITEX_IDLESTACK_SIZE)
+
+#endif /* _ARCH_RISCV_SRC_LITEX_LITEX_MEMORYMAP_H */

arch/risc-v/src/litex/litex_start.c

@@ -0,0 +1,125 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex_init.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stdint.h>
+
+#include <nuttx/config.h>
+
+#include <arch/board/board.h>
+
+#include "litex_clockconfig.h"
+#include "litex.h"
+#include "chip.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#ifdef CONFIG_DEBUG_FEATURES
+#  define showprogress(c) up_lowputc(c)
+#else
+#  define showprogress(c)
+#endif
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/* g_idle_topstack: _sbss is the start of the BSS region as defined by the
+ * linker script. _ebss lies at the end of the BSS region. The idle task
+ * stack starts at the end of BSS and is of size CONFIG_IDLETHREAD_STACKSIZE.
+ * The IDLE thread is the thread that the system boots on and, eventually,
+ * becomes the IDLE, do nothing task that runs only when there is nothing
+ * else to run.  The heap continues from there until the end of memory.
+ * g_idle_topstack is a read-only variable the provides this computed
+ * address.
+ */
+
+uint32_t g_idle_topstack = LITEX_IDLESTACK_TOP;
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: litex_start
+ ****************************************************************************/
+
+void __litex_start(void)
+{
+  const uint32_t *src;
+  uint32_t *dest;
+
+  /* Clear .bss.  We'll do this inline (vs. calling memset) just to be
+   * certain that there are no issues with the state of global variables.
+   */
+
+  for (dest = &_sbss; dest < &_ebss; )
+    {
+      *dest++ = 0;
+    }
+
+  /* Move the initialized data section from his temporary holding spot in
+   * FLASH into the correct place in SRAM.  The correct place in SRAM is
+   * give by _sdata and _edata.  The temporary location is in FLASH at the
+   * end of all of the other read-only data (.text, .rodata) at _eronly.
+   */
+
+  /* for vexriscv the full image is loaded in ddr ram */
+
+  for (src = &_eronly, dest = &_sdata; dest < &_edata; )
+    {
+      *dest++ = *src++;
+    }
+
+  /* Setup PLL */
+
+  litex_clockconfig();
+
+  /* Configure the UART so we can get debug output */
+
+  litex_lowsetup();
+
+  showprogress('A');
+
+#ifdef USE_EARLYSERIALINIT
+  up_earlyserialinit();
+#endif
+
+  showprogress('B');
+
+  /* Do board initialization */
+
+  litex_boardinitialize();
+
+  showprogress('C');
+
+  /* Call nx_start() */
+
+  nx_start();
+
+  /* Shouldn't get here */
+
+  for (; ; );
+}

arch/risc-v/src/litex/litex_timerisr.c

@@ -0,0 +1,202 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex_timerisr.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <time.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/clock.h>
+#include <arch/board/board.h>
+
+#include "up_arch.h"
+
+#include "litex.h"
+#include "litex_clockconfig.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define TICK_COUNT (litex_get_hfclk() / TICK_PER_SEC)
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static bool _b_tick_started = false;
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/* litex mmio registers are a bit odd, by default they are byte-wide
+ * registers that are on 32-bit word boundaries. So a "32-bit" registers
+ * is actually broken into four bytes spanning a total address space of
+ * 16 bytes.
+ */
+
+static inline uint64_t litex_clint_time_read(void)
+{
+  uint64_t r = getreg8(LITEX_CLINT_MTIME);
+  r <<= 8;
+  r |= getreg8(LITEX_CLINT_MTIME + 0x04);
+  r <<= 8;
+  r |= getreg8(LITEX_CLINT_MTIME + 0x08);
+  r <<= 8;
+  r |= getreg8(LITEX_CLINT_MTIME + 0x0c);
+  r <<= 8;
+  r |= getreg8(LITEX_CLINT_MTIME + 0x10);
+  r <<= 8;
+  r |= getreg8(LITEX_CLINT_MTIME + 0x14);
+  r <<= 8;
+  r |= getreg8(LITEX_CLINT_MTIME + 0x18);
+  r <<= 8;
+  r |= getreg8(LITEX_CLINT_MTIME + 0x1c);
+  return r;
+}
+
+static inline uint64_t litex_clint_time_cmp_read(void)
+{
+  uint64_t r = getreg8(LITEX_CLINT_MTIMECMP);
+  r <<= 8;
+  r |= getreg8(LITEX_CLINT_MTIMECMP + 0x04);
+  r <<= 8;
+  r |= getreg8(LITEX_CLINT_MTIMECMP + 0x08);
+  r <<= 8;
+  r |= getreg8(LITEX_CLINT_MTIMECMP + 0x0c);
+  r <<= 8;
+  r |= getreg8(LITEX_CLINT_MTIMECMP + 0x10);
+  r <<= 8;
+  r |= getreg8(LITEX_CLINT_MTIMECMP + 0x14);
+  r <<= 8;
+  r |= getreg8(LITEX_CLINT_MTIMECMP + 0x18);
+  r <<= 8;
+  r |= getreg8(LITEX_CLINT_MTIMECMP + 0x1c);
+  return r;
+}
+
+static inline void litex_clint_time_cmp_write(uint64_t v)
+{
+  putreg8(v >> 56, LITEX_CLINT_MTIMECMP);
+  putreg8(v >> 48, LITEX_CLINT_MTIMECMP + 0x04);
+  putreg8(v >> 40, LITEX_CLINT_MTIMECMP + 0x08);
+  putreg8(v >> 32, LITEX_CLINT_MTIMECMP + 0x0c);
+  putreg8(v >> 24, LITEX_CLINT_MTIMECMP + 0x10);
+  putreg8(v >> 16, LITEX_CLINT_MTIMECMP + 0x14);
+  putreg8(v >> 8, LITEX_CLINT_MTIMECMP + 0x18);
+  putreg8(v, LITEX_CLINT_MTIMECMP + 0x1c);
+}
+
+/* helper function to set/clear csr */
+
+#define csr_clear(csr, val)					\
+({								\
+  unsigned long __v = (unsigned long)(val);		\
+  __asm__ __volatile__ ("csrc " #csr ", %0"		\
+            : : "rK" (__v));			\
+})
+
+#define csr_set(csr, val)					\
+({								\
+  unsigned long __v = (unsigned long)(val);		\
+  __asm__ __volatile__ ("csrs " #csr ", %0"		\
+            : : "rK" (__v));			\
+})
+
+/****************************************************************************
+ * Name:  litex_reload_mtimecmp
+ ****************************************************************************/
+
+static void litex_reload_mtimecmp(void)
+{
+  irqstate_t flags = spin_lock_irqsave();
+
+  uint64_t current;
+  uint64_t next;
+
+  if (!_b_tick_started)
+    {
+      _b_tick_started = true;
+      putreg8(1, LITEX_CLINT_LATCH);
+      current = litex_clint_time_read();
+    }
+  else
+    {
+      current = litex_clint_time_cmp_read();
+    }
+
+  next = current + TICK_COUNT;
+
+  litex_clint_time_cmp_write(next);
+  putreg8(1, LITEX_CLINT_LATCH);
+  csr_set(mie, MIE_MTIE);
+  csr_clear(mip, MIP_MTIP);
+
+  spin_unlock_irqrestore(flags);
+}
+
+/****************************************************************************
+ * Name:  litex_timerisr
+ ****************************************************************************/
+
+static int litex_timerisr(int irq, void *context, FAR void *arg)
+{
+  litex_reload_mtimecmp();
+
+  /* Process timer interrupt */
+
+  nxsched_process_timer();
+  return 0;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_timer_initialize
+ *
+ * Description:
+ *   This function is called during start-up to initialize
+ *   the timer interrupt.
+ *
+ ****************************************************************************/
+
+void up_timer_initialize(void)
+{
+  /* Attach timer interrupt handler */
+
+  irq_attach(LITEX_IRQ_MTIMER, litex_timerisr, NULL);
+
+  /* Reload CLINT mtimecmp */
+
+  litex_reload_mtimecmp();
+
+  /* And enable the timer interrupt */
+
+  up_enable_irq(LITEX_IRQ_MTIMER);
+}

arch/risc-v/src/litex/litex_vectors.S

@@ -0,0 +1,42 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/litex_vectors.S
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/************************************************************************************
+ * Included Files
+ ************************************************************************************/
+
+  .section .text.vec
+  .global  __reset_vec
+  .global  __trap_vec
+
+/****************************************************************************
+ * Name: __reset_vec
+ ****************************************************************************/
+
+__reset_vec:
+  jal  __start
+
+/****************************************************************************
+ * Name: exception_common
+ ****************************************************************************/
+
+__trap_vec:
+  j    exception_common
+  nop

arch/risc-v/src/litex/up_schedulesigaction.c

@@ -0,0 +1,192 @@
+/****************************************************************************
+ * arch/risc-v/src/litex/up_schedulesigaction.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * 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/litex/irq.h>
+
+#include "sched/sched.h"
+#include "up_internal.h"
+#include "up_arch.h"
+
+/****************************************************************************
+ * 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;
+  uint32_t int_ctx;
+
+  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_EPC];
+              tcb->xcp.saved_int_ctx    = g_current_regs[REG_INT_CTX];
+
+              /* Then set up to vector to the trampoline with interrupts
+               * disabled
+               */
+
+              g_current_regs[REG_EPC]     = (uint32_t)up_sigdeliver;
+
+              int_ctx                     = g_current_regs[REG_INT_CTX];
+              int_ctx                    &= ~MSTATUS_MIE;
+
+              g_current_regs[REG_INT_CTX] = int_ctx;
+
+              /* 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_int_ctx,
+                    g_current_regs[REG_EPC], g_current_regs[REG_INT_CTX]);
+            }
+        }
+
+      /* 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_EPC];
+          tcb->xcp.saved_int_ctx    = tcb->xcp.regs[REG_INT_CTX];
+
+          /* Then set up to vector to the trampoline with interrupts
+           * disabled
+           */
+
+          tcb->xcp.regs[REG_EPC]      = (uint32_t)up_sigdeliver;
+
+          int_ctx                     = tcb->xcp.regs[REG_INT_CTX];
+          int_ctx                    &= ~MSTATUS_MIE;
+
+          tcb->xcp.regs[REG_INT_CTX]  = int_ctx;
+
+          sinfo("PC/STATUS Saved: %08x/%08x New: %08x/%08x\n",
+                tcb->xcp.saved_epc, tcb->xcp.saved_int_ctx,
+                tcb->xcp.regs[REG_EPC], tcb->xcp.regs[REG_INT_CTX]);
+        }
+    }
+
+  leave_critical_section(flags);
+}

boards/Kconfig

@@ -43,6 +43,13 @@ config ARCH_BOARD_ARDUINO_M0
 		This options selects the Arduino M0 board featuring the Atmel
 		ATSAMD21 MCU.
 
+config ARCH_BOARD_ARTY_A7
+	bool "DIGILENT ARTY_A7 board"
+	depends on ARCH_CHIP_LITEX
+	---help---
+		This is the board configuration for the port of NuttX to the Digilent ARTY A7
+		board.  This board features the RISC-V litex vexriscv softcore
+
 config ARCH_BOARD_AVR32DEV1
 	bool "Atmel AVR32DEV1 board"
 	depends on ARCH_CHIP_AT32UC3B0256
@@ -2058,6 +2065,7 @@ config ARCH_BOARD
 	default "arduino-mega2560"         if ARCH_BOARD_ARDUINO_MEGA2560
 	default "arduino-due"              if ARCH_BOARD_ARDUINO_DUE
 	default "arduino-m0"               if ARCH_BOARD_ARDUINO_M0
+	default "arty_a7"                  if ARCH_BOARD_ARTY_A7
 	default "avr32dev1"                if ARCH_BOARD_AVR32DEV1
 	default "axoloti"                  if ARCH_BOARD_AXOLOTI
 	default "bambino-200e"             if ARCH_BOARD_BAMBINO_200E
@@ -2819,6 +2827,9 @@ endif
 if ARCH_BOARD_US7032EVB1
 source "boards/renesas/sh1/us7032evb1/Kconfig"
 endif
+if ARCH_BOARD_ARTY_A7
+source "boards/risc-v/litex/arty_a7/Kconfig"
+endif
 if ARCH_BOARD_GAPUINO
 source "boards/risc-v/gap8/gapuino/Kconfig"
 endif

boards/risc-v/litex/arty_a7/Kconfig

@@ -0,0 +1,8 @@
+#
+# For a description of the syntax of this configuration file,
+# see misc/tools/kconfig-language.txt.
+#
+
+if ARCH_BOARD_ARTY_A7
+
+endif

boards/risc-v/litex/arty_a7/README.txt

@@ -0,0 +1,28 @@
+1. Download and install toolchain
+
+  $ curl https://static.dev.sifive.com/dev-tools/riscv64-unknown-elf-gcc-8.3.0-2019.08.0-x86_64-linux-ubuntu14.tar.gz
+
+2. Follow instruction on https://github.com/enjoy-digital/litex to build the vexriscv softcore fpga gateware
+   and flash to arty_a7 board
+
+3. Configure and build NuttX
+
+  $ mkdir ./nuttx; cd ./nuttx
+  $ git clone https://bitbucket.org/nuttx/nuttx.git
+  $ git clone https://bitbucket.org/nuttx/apps.git
+  $ cd nuttx
+  $ make distclean
+  $ ./tools/configure.sh arty_a7:nsh
+  $ make V=1
+
+4. Setup tftp server on your laptop, copy nuttx.bin to your tftpboot directory and change its name to boot.bin
+
+5. Setup the wire connection(uart and tftp) between your board and laptop
+
+6. Run  $ minicom -b 1000000 /dev/ttyUSB1 (the default baudrate on litex vexriscv is 1e6)
+   when you see the bios prompt "litex>", type "netboot" and enter soon comes the nsh prompt
+
+7. TODO
+
+  Support GPIO/SPI/I2C/RTC/WDT/PWM
+  Support RISC-V User mode

boards/risc-v/litex/arty_a7/configs/nsh/defconfig

@@ -0,0 +1,74 @@
+#
+# This file is autogenerated: PLEASE DO NOT EDIT IT.
+#
+# You can use "make menuconfig" to make any modifications to the installed .config file.
+# You can then do "make savedefconfig" to generate a new defconfig file that includes your
+# modifications.
+#
+# CONFIG_NSH_DISABLEBG is not set
+# CONFIG_NSH_DISABLE_LOSMART is not set
+# CONFIG_NSH_DISABLE_UNAME is not set
+# CONFIG_STANDARD_SERIAL is not set
+CONFIG_ARCH="risc-v"
+CONFIG_ARCH_BOARD="arty_a7"
+CONFIG_ARCH_BOARD_ARTY_A7=y
+CONFIG_ARCH_CHIP="litex"
+CONFIG_ARCH_CHIP_LITEX=y
+CONFIG_ARCH_INTERRUPTSTACK=8192
+CONFIG_ARCH_RISCV=y
+CONFIG_ARCH_STACKDUMP=y
+CONFIG_BINFMT_DISABLE=y
+CONFIG_BOARD_LOOPSPERMSEC=10000
+CONFIG_BUILTIN=y
+CONFIG_DEBUG_FULLOPT=y
+CONFIG_DEBUG_SYMBOLS=y
+CONFIG_DEFAULT_SMALL=y
+CONFIG_DEV_ZERO=y
+CONFIG_DISABLE_MQUEUE=y
+CONFIG_EXAMPLES_HELLO=y
+CONFIG_EXAMPLES_HELLO_STACKSIZE=8192
+CONFIG_FS_PROCFS=y
+CONFIG_FS_WRITABLE=y
+CONFIG_IDLETHREAD_STACKSIZE=8192
+CONFIG_INTELHEX_BINARY=y
+CONFIG_LIBC_PERROR_STDOUT=y
+CONFIG_LIBC_STRERROR=y
+CONFIG_MAX_TASKS=8
+CONFIG_MAX_WDOGPARMS=2
+CONFIG_NFILE_DESCRIPTORS=6
+CONFIG_NFILE_STREAMS=6
+CONFIG_NSH_ARCHINIT=y
+CONFIG_NSH_BUILTIN_APPS=y
+CONFIG_NSH_DISABLE_CD=y
+CONFIG_NSH_DISABLE_CP=y
+CONFIG_NSH_DISABLE_IFUPDOWN=y
+CONFIG_NSH_DISABLE_MKDIR=y
+CONFIG_NSH_DISABLE_RM=y
+CONFIG_NSH_DISABLE_RMDIR=y
+CONFIG_NSH_DISABLE_UMOUNT=y
+CONFIG_NSH_FILEIOSIZE=64
+CONFIG_NSH_STRERROR=y
+CONFIG_PREALLOC_TIMERS=0
+CONFIG_PREALLOC_WDOGS=4
+CONFIG_PTHREAD_STACK_DEFAULT=8192
+CONFIG_RAM_SIZE=134217728
+CONFIG_RAM_START=0xc0800000
+CONFIG_RAW_BINARY=y
+CONFIG_RR_INTERVAL=200
+CONFIG_RV32IM_CUSTOM_IRQ_SUPPORT=y
+CONFIG_SCHED_WAITPID=y
+CONFIG_STACK_COLORATION=y
+CONFIG_START_DAY=20
+CONFIG_START_MONTH=3
+CONFIG_START_YEAR=2020
+CONFIG_STDIO_DISABLE_BUFFERING=y
+CONFIG_SYSTEM_NSH=y
+CONFIG_TASK_NAME_SIZE=12
+CONFIG_TASK_SPAWN_DEFAULT_STACKSIZE=8192
+CONFIG_TESTING_GETPRIME=y
+CONFIG_UART0_RXBUFSIZE=128
+CONFIG_UART0_SERIAL_CONSOLE=y
+CONFIG_UART0_TXBUFSIZE=128
+CONFIG_USERMAIN_STACKSIZE=8192
+CONFIG_USER_ENTRYPOINT="nsh_main"
+CONFIG_WDOG_INTRESERVE=0

boards/risc-v/litex/arty_a7/include/board.h

@@ -0,0 +1,68 @@
+/****************************************************************************
+ * boards/risc-v/litex/arty_a7/include/board.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __BOARDS_RISCV_LITEX_ARTY_A7_INCLUDE_BOARD_H
+#define __BOARDS_RISCV_LITEX_ARTY_A7_INCLUDE_BOARD_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+#undef EXTERN
+#if defined(__cplusplus)
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: litex_boardinitialize
+ ****************************************************************************/
+
+void litex_boardinitialize(void);
+
+#undef EXTERN
+#if defined(__cplusplus)
+}
+#endif
+#endif /* __ASSEMBLY__ */
+#endif /* __BOARDS_RISC-V_LITEX_ARTY_A7_INCLUDE_BOARD_H */

boards/risc-v/litex/arty_a7/scripts/Make.defs

@@ -0,0 +1,96 @@
+############################################################################
+# boards/risc-v/litex/arty_a7/scripts/Make.defs
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.  The
+# ASF licenses this file to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance with the
+# License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+############################################################################
+
+include ${TOPDIR}/.config
+include ${TOPDIR}/tools/Config.mk
+include ${TOPDIR}/arch/risc-v/src/rv32im/Toolchain.defs
+
+LDSCRIPT = ld.script
+
+ifeq ($(WINTOOL),y)
+  # Windows-native toolchains
+  DIRLINK = $(TOPDIR)/tools/copydir.sh
+  DIRUNLINK = $(TOPDIR)/tools/unlink.sh
+  MKDEP = $(TOPDIR)/tools/mkwindeps.sh
+  ARCHINCLUDES = -I. -isystem "${shell cygpath -w $(TOPDIR)/include}"
+  ARCHXXINCLUDES = -I. -isystem "${shell cygpath -w $(TOPDIR)/include}" -isystem "${shell cygpath -w $(TOPDIR)/include/cxx}"
+  ARCHSCRIPT = -T "${shell cygpath -w $(TOPDIR)/boards/$(CONFIG_ARCH)/$(CONFIG_ARCH_CHIP)/$(CONFIG_ARCH_BOARD)/scripts/$(LDSCRIPT)}"
+else
+  # Linux/Cygwin-native toolchain
+  MKDEP = $(TOPDIR)/tools/mkdeps$(HOSTEXEEXT)
+  ARCHINCLUDES = -I. -isystem $(TOPDIR)/include
+  ARCHXXINCLUDES = -I. -isystem $(TOPDIR)/include -isystem $(TOPDIR)/include/cxx
+  ARCHSCRIPT = -T$(TOPDIR)/boards/$(CONFIG_ARCH)/$(CONFIG_ARCH_CHIP)/$(CONFIG_ARCH_BOARD)/scripts/$(LDSCRIPT)
+endif
+
+CC = $(CROSSDEV)gcc
+CXX = $(CROSSDEV)g++
+CPP = $(CROSSDEV)gcc -E
+LD = $(CROSSDEV)ld
+STRIP = $(CROSSDEV)strip --strip-unneeded
+AR = $(ARCROSSDEV)ar rcs
+NM = $(ARCROSSDEV)nm
+OBJCOPY = $(CROSSDEV)objcopy
+OBJDUMP = $(CROSSDEV)objdump
+
+ARCHCCVERSION = ${shell $(CC) -v 2>&1 | sed -n '/^gcc version/p' | sed -e 's/^gcc version \([0-9\.]\)/\1/g' -e 's/[-\ ].*//g' -e '1q'}
+ARCHCCMAJOR = ${shell echo $(ARCHCCVERSION) | cut -d'.' -f1}
+
+ifeq ($(CONFIG_DEBUG_SYMBOLS),y)
+  ARCHOPTIMIZATION = -g
+  ASARCHCPUFLAGS += -Wa,-g
+endif
+
+MAXOPTIMIZATION = -Os
+
+ifneq ($(CONFIG_DEBUG_NOOPT),y)
+  ARCHOPTIMIZATION += $(MAXOPTIMIZATION) -fno-strict-aliasing -fno-strength-reduce -fomit-frame-pointer
+endif
+
+ARCHCPUFLAGS = -march=rv32ima -mabi=ilp32
+ARCHCFLAGS = -fno-builtin -ffunction-sections -fdata-sections
+ARCHCXXFLAGS = -fno-builtin -fno-exceptions -fcheck-new -fno-rtti
+ARCHWARNINGS = -Wall -Wstrict-prototypes -Wshadow -Wundef
+ARCHWARNINGSXX = -Wall -Wshadow -Wundef
+ARCHDEFINES =
+ARCHPICFLAGS = -fpic -msingle-pic-base -mpic-register=r10
+
+CFLAGS = $(ARCHCFLAGS) $(ARCHWARNINGS) $(ARCHOPTIMIZATION) $(ARCHCPUFLAGS) $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRADEFINES) -pipe
+CPICFLAGS = $(ARCHPICFLAGS) $(CFLAGS)
+CXXFLAGS = $(ARCHCXXFLAGS) $(ARCHWARNINGSXX) $(ARCHOPTIMIZATION) $(ARCHCPUFLAGS) $(ARCHXXINCLUDES) $(ARCHDEFINES) $(EXTRADEFINES) -pipe
+CXXPICFLAGS = $(ARCHPICFLAGS) $(CXXFLAGS)
+CPPFLAGS = $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRADEFINES)
+AFLAGS += $(CFLAGS) -D__ASSEMBLY__ $(ASARCHCPUFLAGS)
+
+NXFLATLDFLAGS1 = -r -d -warn-common
+NXFLATLDFLAGS2 = $(NXFLATLDFLAGS1) -T$(TOPDIR)/binfmt/libnxflat/gnu-nxflat-pcrel.ld -no-check-sections
+LDNXFLATFLAGS = -e main -s 2048
+
+ASMEXT = .S
+OBJEXT = .o
+LIBEXT = .a
+EXEEXT =
+
+LDFLAGS += --gc-sections -melf32lriscv
+
+HOSTCC = gcc
+HOSTINCLUDES = -I.
+HOSTCFLAGS = -Wall -Wstrict-prototypes -Wshadow -Wundef -g -pipe
+HOSTLDFLAGS =

boards/risc-v/litex/arty_a7/scripts/ld.script

@@ -0,0 +1,93 @@
+/****************************************************************************
+ * boards/risc-v/litex/arty_a7/scripts/ld.script
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+MEMORY
+{
+  progmem (rx) : ORIGIN = 0xc0000000, LENGTH = 8M
+  sram (rwx) : ORIGIN = 0xc0800000, LENGTH = 256M - 8M
+}
+
+OUTPUT_ARCH("riscv")
+
+ENTRY(_stext)
+EXTERN(_vectors)
+SECTIONS
+{
+    .text : {
+        _stext = ABSOLUTE(.);
+        *(.vectors)
+        *(.text .text.*)
+        *(.fixup)
+        *(.gnu.warning)
+        *(.rodata .rodata.* .srodata .srodata.*)
+        *(.gnu.linkonce.t.*)
+        *(.glue_7)
+        *(.glue_7t)
+        *(.got)
+        *(.gcc_except_table)
+        *(.gnu.linkonce.r.*)
+        _etext = ABSOLUTE(.);
+    } > progmem
+
+    .init_section : ALIGN(4) {
+        _sinit = ABSOLUTE(.);
+        KEEP(*(.init_array .init_array.*))
+        _einit = ABSOLUTE(.);
+    } > progmem
+
+    _eronly = ABSOLUTE(.);
+
+    .data : ALIGN(4) {
+        _sdata = ABSOLUTE(.);
+        *(.data .data.*)
+        *(.sdata .sdata.* .sdata2.*)
+        *(.gnu.linkonce.d.*)
+        *(.gnu.linkonce.s.*)
+        CONSTRUCTORS
+        . = ALIGN(4);
+        _edata = ABSOLUTE(.);
+    } > sram AT > progmem
+
+    .bss : ALIGN(4) {
+        _sbss = ABSOLUTE(.);
+        *(.bss .bss.*)
+        *(.sbss .sbss.*)
+        *(.gnu.linkonce.b.*)
+        *(.gnu.linkonce.sb.*)
+        *(COMMON)
+        . = ALIGN(4);
+        _ebss = ABSOLUTE(.);
+    } > sram
+
+    /* Stabs debugging sections. */
+
+    .stab 0 : { *(.stab) }
+    .stabstr 0 : { *(.stabstr) }
+    .stab.excl 0 : { *(.stab.excl) }
+    .stab.exclstr 0 : { *(.stab.exclstr) }
+    .stab.index 0 : { *(.stab.index) }
+    .stab.indexstr 0 : { *(.stab.indexstr) }
+    .comment 0 : { *(.comment) }
+    .debug_abbrev 0 : { *(.debug_abbrev) }
+    .debug_info 0 : { *(.debug_info) }
+    .debug_line 0 : { *(.debug_line) }
+    .debug_pubnames 0 : { *(.debug_pubnames) }
+    .debug_aranges 0 : { *(.debug_aranges) }
+}

boards/risc-v/litex/arty_a7/src/Makefile

@@ -0,0 +1,29 @@
+############################################################################
+# boards/risc-v/litex/arty_a7/src/Makefile
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.  The
+# ASF licenses this file to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance with the
+# License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+############################################################################
+
+-include $(TOPDIR)/Make.defs
+
+CSRCS  = litex_bringup.c litex_boot.c
+
+ifeq ($(CONFIG_LIB_BOARDCTL),y)
+CSRCS += litex_appinit.c
+endif
+
+include $(TOPDIR)/boards/Board.mk

boards/risc-v/litex/arty_a7/src/arty_a7.h

@@ -0,0 +1,32 @@
+/****************************************************************************
+ * boards/risc-v/litex/arty_a7/src/arty_a7.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __BOARDS_RISCV_LITEX_ARTY_A7_SRC_ARTY_A7_H
+#define __BOARDS_RISCV_LITEX_ARTY_A7_SRC_ARTY_A7_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+int litex_bringup(void);
+
+#endif /* __BOARDS_RISCV_LITEX_ARTY_A7_SRC_ARTY_A7_H */

boards/risc-v/litex/arty_a7/src/litex_appinit.c

@@ -0,0 +1,75 @@
+/****************************************************************************
+ * boards/risc-v/litex/arty_a7/src/litex_appinit.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <syslog.h>
+#include <errno.h>
+
+#include <nuttx/board.h>
+
+#include "litex.h"
+#include "arty_a7.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: board_app_initialize
+ *
+ * Description:
+ *   Perform architecture specific initialization
+ *
+ * Input Parameters:
+ *   arg - The boardctl() argument is passed to the board_app_initialize()
+ *         implementation without modification.  The argument has no
+ *         meaning to NuttX; the meaning of the argument is a contract
+ *         between the board-specific initialization logic and the
+ *         matching application logic.  The value cold be such things as a
+ *         mode enumeration value, a set of DIP switch switch settings, a
+ *         pointer to configuration data read from a file or serial FLASH,
+ *         or whatever you would like to do with it.  Every implementation
+ *         should accept zero/NULL as a default configuration.
+ *
+ * Returned Value:
+ *   Zero (OK) is returned on success; a negated errno value is returned on
+ *   any failure to indicate the nature of the failure.
+ *
+ ****************************************************************************/
+
+int board_app_initialize(uintptr_t arg)
+{
+#ifdef CONFIG_BOARD_LATE_INITIALIZE
+  /* Board initialization already performed by board_late_initialize() */
+
+  return OK;
+#else
+  /* Perform board-specific initialization */
+
+  return litex_bringup();
+#endif
+}

boards/risc-v/litex/arty_a7/src/litex_boot.c

@@ -0,0 +1,57 @@
+/****************************************************************************
+ * boards/risc-v/litex/arty_a7/src/litex_boot.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <debug.h>
+
+#include <nuttx/board.h>
+#include <arch/board/board.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: litex_boardinitialize
+ *
+ * Description:
+ *   All LITEX architectures must provide the following entry point.
+ *   This entry point is called early in the initialization -- after all
+ *   memory has been configured and mapped but before any devices have been
+ *   initialized.
+ *
+ ****************************************************************************/
+
+void litex_boardinitialize(void)
+{
+}

boards/risc-v/litex/arty_a7/src/litex_bringup.c

@@ -0,0 +1,61 @@
+/****************************************************************************
+ * boards/risc-v/litex/arty_a7/src/litex_bringup.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/mount.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <syslog.h>
+#include <errno.h>
+
+#include <nuttx/board.h>
+#include <nuttx/input/buttons.h>
+
+#include "litex.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: litex_bringup
+ ****************************************************************************/
+
+int litex_bringup(void)
+{
+  int ret = OK;
+
+#ifdef CONFIG_FS_PROCFS
+  /* Mount the procfs file system */
+
+  ret = mount(NULL, "/proc", "procfs", 0, NULL);
+  if (ret < 0)
+    {
+      serr("ERROR: Failed to mount procfs at %s: %d\n", "/proc", ret);
+    }
+#endif
+
+  return ret;
+}

boards/risc-v/litex/drivers/Kconfig

@@ -0,0 +1,4 @@
+#
+# For a description of the syntax of this configuration file,
+# see the file kconfig-language.txt in the NuttX tools repository.
+#