arch/: Make sure the up_irq_enable() is available on all architectures. I will not be able to test all of these new versions of this function so this may break things for awhile.

arch/arm/include/arm/irq.h

@@ -118,19 +118,19 @@
 /* This struct defines the way the registers are stored.  We
  * need to save:
  *
- *  1	CPSR
+ *  1  CPSR
- *  7	Static registers, v1-v7 (aka r4-r10)
+ *  7  Static registers, v1-v7 (aka r4-r10)
- *  1	Frame pointer, fp (aka r11)
+ *  1  Frame pointer, fp (aka r11)
- *  1	Stack pointer, sp (aka r13)
+ *  1  Stack pointer, sp (aka r13)
- *  1	Return address, lr (aka r14)
+ *  1  Return address, lr (aka r14)
  * ---
- * 11	(XCPTCONTEXT_USER_REG)
+ * 11  (XCPTCONTEXT_USER_REG)
  *
  * On interrupts, we also need to save:
- *  4	Volatile registers, a1-a4 (aka r0-r3)
+ *  4  Volatile registers, a1-a4 (aka r0-r3)
- *  1	Scratch Register, ip (aka r12)
+ *  1  Scratch Register, ip (aka r12)
- *---
+ * ---
- *  5	(XCPTCONTEXT_IRQ_REGS)
+ *  5  (XCPTCONTEXT_IRQ_REGS)
  *
  * For a total of 17 (XCPTCONTEXT_REGS)
  */
@@ -212,6 +212,23 @@ static inline void up_irq_restore(irqstate_t flags)
      : "r" (flags)
      : "memory");
 }
+
+/* Enable IRQs and return the previous IRQ state */
+
+static inline irqstate_t up_irq_enable(void)
+{
+  unsigned int flags;
+  unsigned int temp;
+  __asm__ __volatile__
+    (
+     "\tmrs    %0, cpsr\n"
+     "\tbic    %1, %0, #128\n"
+     "\tmsr    cpsr_c, %1"
+     : "=r" (flags), "=r" (temp)
+     :
+     : "memory");
+  return flags;
+}
 #endif /* __ASSEMBLY__ */
 
 /****************************************************************************

arch/arm/include/armv7-a/irq.h

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/arm/include/armv7-a/irq.h
  *
- *   Copyright (C) 2013-2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2013-2014, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without

arch/avr/include/avr32/irq.h

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/avr/include/avr32/irq.h
  *
- *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2010, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -167,7 +167,7 @@ static inline uint32_t avr32_evba(void)
   return evba;
 }
 
-/* Save the current interrupt enable state & disable all interrupts */
+/* Return the current interrupt enable state and disable all interrupts */
 
 static inline irqstate_t up_irq_save(void)
 {
@@ -185,7 +185,7 @@ static inline irqstate_t up_irq_save(void)
 /* Restore saved interrupt state */
 
 static inline void up_irq_restore(irqstate_t flags)
-{
+{ 
   if ((flags & AVR32_SR_GM_MASK) == 0)
     {
       __asm__ __volatile__ (
@@ -198,6 +198,21 @@ static inline void up_irq_restore(irqstate_t flags)
     }
 }
 
+/* Return the current interrupt enable state and enable all interrupts */
+
+static inline irqstate_t up_irq_enable(void)
+{
+  irqstate_t sr = (irqstate_t)avr32_sr();
+  __asm__ __volatile__ (
+    "csrf\t%0\n\t"
+    "nop\n\t"
+    "nop"
+    :
+    : "i" (AVR32_SR_GM_SHIFT)
+  );
+  return sr;
+}
+
 #endif /* __ASSEMBLY__ */
 
 /****************************************************************************

arch/mips/include/mips32/irq.h

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/mips/include/mips32/irq.h
  *
- *   Copyright (C) 2011, 2013, 2015 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2011, 2013, 2015, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -557,6 +557,22 @@ irqstate_t up_irq_save(void);
 
 void up_irq_restore(irqstate_t irqtate);
 
+/****************************************************************************
+ * Name: up_irq_enable
+ *
+ * Description:
+ *   Enable interrupts
+ *
+ * Input Parameters:
+ *   None.
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void up_irq_enable(void);
+
 #undef EXTERN
 #ifdef __cplusplus
 }

arch/mips/src/mips32/up_initialstate.c

@@ -50,18 +50,6 @@
 #include "up_internal.h"
 #include "up_arch.h"
 
-/****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
-
-/****************************************************************************
- * Private Data
- ****************************************************************************/
-
-/****************************************************************************
- * Private Functions
- ****************************************************************************/
-
 /****************************************************************************
  * Public Functions
  ****************************************************************************/

arch/mips/src/mips32/up_irq.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/mips/src/mips32/up_irq.c
  *
- *   Copyright (C) 2011 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2011, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -78,7 +78,7 @@ irqstate_t up_irq_save(void)
  * Name: up_irq_restore
  *
  * Description:
- *   Restore the previous interrutp state (i.e., the one previously returned
+ *   Restore the previous up_irq_enable state (i.e., the one previously returned
  *   by up_irq_save())
  *
  * Input Parameters:
@@ -100,3 +100,38 @@ void up_irq_restore(irqstate_t irqstate)
   status   |= CP0_STATUS_IM_SWINTS; /* Make sure that S/W interrupts enabled */
   cp0_putstatus(status);            /* Restore interrupt state */
 }
+
+/****************************************************************************
+ * Name: up_irq_enable
+ *
+ * Description:
+ *   Enable interrupts
+ *
+ * Input Parameters:
+ *   None.
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void up_irq_enable(void)
+{
+  register irqstate_t status;
+
+  /* Set the status register.  It will be the same as the current status
+   * register with some changes:
+   *
+   * 1. Clear the BEV bit (This bit should already be clear)
+   * 2. Clear the UM bit so that the task executes in kernel mode
+   *   (This bit should already be clear)
+   * 3. Make sure the IE is set
+   * 4. Make sure the S/W interrupts are enabled
+   * 5. Set the interrupt mask bits
+   */
+
+  status  = cp0_getstatus();
+  status &= ~(CP0_STATUS_BEV | CP0_STATUS_UM);
+  status |=  (CP0_STATUS_IE | CP0_STATUS_IM_SWINTS | CP0_STATUS_IM_ALL);
+  cp0_putstatus(status);
+}

arch/misoc/include/irq.h

@@ -70,6 +70,7 @@ extern "C"
 
 irqstate_t up_irq_save(void);
 void up_irq_restore(irqstate_t flags);
+irqstate_t up_irq_enable(void);
 
 #undef EXTERN
 #ifdef __cplusplus

arch/misoc/src/lm32/lm32_irq.c

@@ -82,6 +82,7 @@ void lm32_irq_initialize(void)
  * Name: up_irq_save
  *
  * Description:
+ *   Return the current interrupt enable state and disable all interrupts.
  *
  ****************************************************************************/
 
@@ -103,6 +104,7 @@ irqstate_t up_irq_save(void)
  * Name: up_irq_restore
  *
  * Description:
+ *   Restore saved interrupt state
  *
  ****************************************************************************/
 
@@ -113,6 +115,28 @@ void up_irq_restore(irqstate_t flags)
   irq_setie(flags);
 }
 
+/****************************************************************************
+ * Name: up_irq_enable
+ *
+ * Description:
+ *   Return the current interrupt enable state and enable all interrupts
+ *
+ ****************************************************************************/
+
+irqstate_t up_irq_restore(irqstate_t flags)
+{
+  irqstate_t flags;
+
+  /* Get the previous value of IE */
+
+  flags = irq_getie();
+
+  /* Enable interrupts and return the previous interrupt state */
+
+  irq_setie(1);
+  return flags;
+}
+
 /****************************************************************************
  * Name: up_disable_irq
  *

arch/renesas/include/m16c/irq.h

@@ -1,7 +1,7 @@
 /************************************************************************************
  * arch/renesas/include/m16c/irq.h
  *
- *   Copyright (C) 2009 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2009, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -289,33 +289,48 @@ extern "C"
  * leave_critical section(), are probably what you really want.
  */
 
-/* Save the current interrupt enable state & disable IRQs */
+/* Return the current interrupt enable state and disable IRQs */
 
 static inline irqstate_t up_irq_save(void)
 {
   irqstate_t flags;
   __asm__ __volatile__
     (
-     "\tstc	flg, %0\n"
+     "\tstc  flg, %0\n"
-     "\tfclr	I\n"
+     "\tfclr I\n"
      : "=r" (flags)
      :
      : "memory");
   return flags;
 }
 
-/* Restore saved IRQ & FIQ state */
+/* Restore saved IRQ state */
 
 static inline void up_irq_restore(irqstate_t flags)
 {
   __asm__ __volatile__
     (
-     "ldc	%0, flg"
+     "ldc    %0, flg"
      :
      : "r" (flags)
      : "memory");
 }
 
+/* Return the current interrupt enable state and enable IRQs */
+
+static inline irqstate_t up_irq_enable(void)
+{
+  irqstate_t flags;
+  __asm__ __volatile__
+    (
+     "\tstc  flg, %0\n"
+     "\tfset I\n"
+     : "=r" (flags)
+     :
+     : "memory");
+  return flags;
+}
+
 #endif
 
 /************************************************************************************

arch/renesas/include/sh1/irq.h

@@ -514,7 +514,7 @@ static inline void __setsr(irqstate_t sr)
   __asm__ __volatile__ ("ldc %0, sr" : : "r" (sr));
 }
 
-/* Return the current interrupt enable state & disable IRQs */
+/* Return the current interrupt enable state and disable interrupts */
 
 static inline irqstate_t up_irq_save(void)
 {
@@ -523,14 +523,15 @@ static inline irqstate_t up_irq_save(void)
   return flags;
 }
 
-/* Disable IRQs */
+/* Disable interrupts */
 
 static inline void up_irq_disable(void)
 {
   uint32_t flags = __getsr();
   __setsr(flags | 0x000000f0);
 }
-/* Enable IRQs */
+
+/* Enable interrupts */
 
 static inline void up_irq_enable(void)
 {
@@ -538,7 +539,7 @@ static inline void up_irq_enable(void)
   __setsr(flags & ~0x000000f0);
 }
 
-/* Restore saved IRQ state */
+/* Restore saved interrupt state */
 
 static inline void up_irq_restore(irqstate_t flags)
 {

arch/renesas/src/m16c/m16c_initialstate.c

@@ -48,18 +48,6 @@
 #include "up_internal.h"
 #include "up_arch.h"
 
-/****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
-
-/****************************************************************************
- * Private Data
- ****************************************************************************/
-
-/****************************************************************************
- * Private Functions
- ****************************************************************************/
-
 /****************************************************************************
  * Public Functions
  ****************************************************************************/

arch/risc-v/include/nr5m100/irq.h

@@ -66,6 +66,7 @@
 
 irqstate_t up_irq_save(void);
 void up_irq_restore(irqstate_t irqstate);
+irqstate_t up_irq_enable(void);
 
 #endif /* __ARCH_RISCV_INCLUDE_NR5M100_IRQ_H */
 

arch/risc-v/include/rv32im/irq.h

@@ -344,4 +344,3 @@ struct xcptcontext
  ****************************************************************************/
 
 #endif /* __ARCH_RISCV_INCLUDE_RV32IM_IRQ_H */
-

arch/risc-v/src/nr5m100/nr5_irq.c

@@ -204,7 +204,6 @@ void up_irqinitialize(void)
   /* Now enable Global Interrupts */
 
   __asm__ volatile("csrrs a0, %0, 3" :: "i"(NR5_EPIC_PRIMASK));
-
 }
 
 /****************************************************************************
@@ -283,31 +282,31 @@ int up_prioritize_irq(int irq, int priority)
 #endif
 
 /****************************************************************************
- * Name: irqsave
+ * Name: up_irq_save
  *
  * Description:
- *   Disable IRQs while returning the previous IRQ state
+ *   Return the current interrupt state and disable interrupts
  *
  ****************************************************************************/
 
 irqstate_t up_irq_save(void)
 {
-  irqstate_t   newIrqPri = (2 << 2) | 3;
+  irqstate_t   newpri = (2 << 2) | 3;
-  irqstate_t   oldIrqPri;
+  irqstate_t   oldpri;
 
   /* Set the new IRQ Priority level to level 2, enabled.
    * This will allow SW and DEBUG / TRAP interrupts to
    * continue to fire, but no general purpose ints.
    */
 
-  __asm__ volatile("csrrw %0, %1, %2" : "=r"(oldIrqPri) :
+  __asm__ volatile("csrrw %0, %1, %2" : "=r"(oldpri) :
-               "i"(NR5_EPIC_PRIMASK), "r"(newIrqPri));
+                   "i"(NR5_EPIC_PRIMASK), "r"(newpri));
 
-  return oldIrqPri;
+  return oldpri;
 }
 
 /****************************************************************************
- * Name: irqrestore
+ * Name: up_irq_restore
  *
  * Description:
  *   Restore previous IRQ mask state
@@ -318,3 +317,26 @@ void up_irq_restore(irqstate_t pri)
 {
   __asm__ volatile("csrw %0, %1" :: "i"(NR5_EPIC_PRIMASK), "r"(pri));
 }
+
+/****************************************************************************
+ * Name: up_irq_enable
+ *
+ * Description:
+ *   Return the current interrupt state and enable interrupts
+ *
+ ****************************************************************************/
+
+irqstate_t up_irq_enable(void)
+{
+  irqstate_t   newpri = up_get_newintctx();
+  irqstate_t   oldpri;
+
+  /* Set the new IRQ Priority level to level 5, enabled.  This will allow
+   * all interrupt.
+   */
+
+  __asm__ volatile("csrrw %0, %1, %2" : "=r"(oldpri) :
+                   "i"(NR5_EPIC_PRIMASK), "r"(newpri));
+
+  return oldpri;
+}

arch/risc-v/src/rv32im/up_initialstate.c

@@ -49,18 +49,6 @@
 #include "up_internal.h"
 #include "up_arch.h"
 
-/****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
-
-/****************************************************************************
- * Private Data
- ****************************************************************************/
-
-/****************************************************************************
- * Private Functions
- ****************************************************************************/
-
 /****************************************************************************
  * Public Functions
  ****************************************************************************/

arch/z16/include/z16f/irq.h

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/z16/include/z16f/irq.h
  *
- *   Copyright (C) 2008, 2012, 2015 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2008, 2012, 2015, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -198,6 +198,7 @@ struct xcptcontext
  *
  *   irqstate_t up_irq_save(void);
  *   void up_irq_restore(irqstate_t flags);
+ *   void up_irq_enable(void);
  *
  * NOTE: These functions should never be called from application code and,
  * as a general rule unless you really know what you are doing, this
@@ -209,6 +210,7 @@ struct xcptcontext
 #ifdef __ZILOG__
 #  define up_irq_save()     TDI()
 #  define up_irq_restore(f) RI(f)
+#  define up_irq_enable()   EI()
 #endif
 
 /****************************************************************************

arch/z80/include/ez80/irq.h

@@ -251,7 +251,7 @@ extern "C"
 
 /* Name: up_irq_save, up_irq_restore, and friends.
  *
- * NOTE: This function should never be called from application code and,
+ * NOTE: These functions should never be called from application code and,
  * as a general rule unless you really know what you are doing, this
  * function should not be called directly from operation system code either:
  * Typically, the wrapper functions, enter_critical_section() and
@@ -259,7 +259,8 @@ extern "C"
  */
 
 irqstate_t up_irq_save(void);
-void up_irq_restore(irqstate_t flags);
+void       up_irq_restore(irqstate_t flags);
+irqstate_t up_irq_enable(void);
 
 #undef EXTERN
 #ifdef __cplusplus

arch/z80/include/z180/irq.h

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/z80/include/z180/irq.h
  *
- *   Copyright (C) 2012, 2015 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2012, 2015, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -233,6 +233,7 @@ extern "C"
 
 irqstate_t up_irq_save(void) __naked;
 void       up_irq_restore(irqstate_t flags) __naked;
+irqstate_t up_irq_enable(void);
 
 #undef EXTERN
 #ifdef __cplusplus

arch/z80/include/z8/irq.h

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/z80/include/z8/irq.h
  *
- *   Copyright (C) 2008-2009, 2015 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2008-2009, 2015, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -357,7 +357,7 @@ extern "C"
 
 /* Name: up_irq_save, up_irq_restore, and friends.
  *
- * NOTE: This function should never be called from application code and,
+ * NOTE: These functions should never be called from application code and,
  * as a general rule unless you really know what you are doing, this
  * function should not be called directly from operation system code either:
  * Typically, the wrapper functions, enter_critical_section() and
@@ -365,7 +365,8 @@ extern "C"
  */
 
 irqstate_t up_irq_save(void);
-void up_irq_restore(irqstate_t flags);
+void       up_irq_restore(irqstate_t flags);
+irqstate_t up_irq_enable(void);
 
 #undef EXTERN
 #ifdef __cplusplus

arch/z80/include/z80/irq.h

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/z80/include/z80/irq.h
  *
- *   Copyright (C) 2007-2009, 2015 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2015, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -150,6 +150,7 @@ extern "C"
 
 irqstate_t up_irq_save(void) __naked;
 void       up_irq_restore(irqstate_t flags) __naked;
+irqstate_t up_irq_enable(void);
 
 #undef EXTERN
 #ifdef __cplusplus

arch/z80/src/ez80/ez80_irqsave.asm

@@ -1,7 +1,7 @@
 ;**************************************************************************
 ; arch/z80/src/ez80/ez80_irqsave.asm
 ;
-;   Copyright (C) 2008 Gregory Nutt. All rights reserved.
+;   Copyright (C) 2008, 2018 Gregory Nutt. All rights reserved.
 ;   Author: Gregory Nutt <gnutt@nuttx.org>
 ;
 ; Redistribution and use in source and binary forms, with or without
@@ -60,11 +60,11 @@
 ;**************************************************************************
 
 _up_irq_save:
-	ld	a, i		; AF = interrupt state
+	ld		a, i			; AF = interrupt state
-	di			; Interrupts are disabled (does not affect F)
+	di						; Interrupts are disabled (does not affect F)
-	push	af		; Transfer to HL via the stack
+	push	af				; Transfer to HL via the stack
-	pop	hl		;
+	pop		hl				;
-	ret			; And return
+	ret						; And return
 
 ;**************************************************************************
 ;* Name: void up_irq_restore(irqstate_t flags)
@@ -75,14 +75,29 @@ _up_irq_save:
 ;**************************************************************************
 
 _up_irq_restore:
-	di			; Assume disabled
+	di						; Assume disabled
-	pop	hl		; HL = return address
+	pop		hl				; HL = return address
-	pop	af		; AF Parity bit holds interrupt state
+	pop		af				; AF Parity bit holds interrupt state
-	jp	po, _disabled	; Skip over re-enable if Parity odd
+	jp		po, _disabled	; Skip over re-enable if Parity odd
-	ei			; Re-enable interrupts
+	ei						; Re-enable interrupts
 _disabled:
-	push	af		; Restore stack
+	push	af				; Restore stack
-	push	hl		;
+	push	hl				;
-	ret			; and return
+	ret						; and return
+
+;**************************************************************************
+;* Name: irqstate_t up_irq_enable(void)
+;*
+;* Description:
+;*   Enable all interrupts; return previous interrupt state
+;*
+;**************************************************************************
+
+up_irq_enable:
+	ld		a, i			; AF = interrupt state
+	ei						; Interrupts are enabled (does not affect F)
+	push	af				; Transfer to HL via the stack
+	pop		hl				;
+	ret						; And return
 
 	end

arch/z80/src/z180/z180_irq.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/z80/src/z180/z180_irq.c
  *
- *   Copyright (C) 2012 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2012, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -109,11 +109,11 @@ static void z180_seti(uint8_t value) __naked
 irqstate_t up_irq_save(void) __naked
 {
   __asm
-	ld	a, i		; AF Parity bit holds interrupt state
+	ld		a, i	; AF Parity bit holds interrupt state
-	di			; Interrupts are disabled
+	di				; Interrupts are disabled
 	push	af		; Return AF in HL
-	pop	hl		;
+	pop		hl		;
-	ret			;
+	ret				;
   __endasm;
 }
 
@@ -128,15 +128,34 @@ irqstate_t up_irq_save(void) __naked
 void up_irq_restore(irqstate_t flags) __naked
 {
   __asm
-	di			; Assume disabled
+	di				; Assume disabled
-	pop	hl		; HL = return address
+	pop		hl		; HL = return address
-	pop	af		; AF Parity bit holds interrupt state
+	pop		af		; AF Parity bit holds interrupt state
-	jp	po, statedisable
+	jp		po, statedisable
 	ei
 statedisable:
 	push	af		; Restore stack
 	push	hl		;
-	ret			; and return
+	ret				; and return
+  __endasm;
+}
+
+/****************************************************************************
+ * Name: up_irq_enable
+ *
+ * Description:
+ *   Enable all interrupts; return previous interrupt state
+ *
+ ****************************************************************************/
+
+irqstate_t up_irq_enable(void) __naked
+{
+  __asm
+	ld		a, i	; AF Parity bit holds interrupt state
+	ei				; Interrupts are enabled
+	push	af		; Return AF in HL
+	pop		hl		;
+	ret				;
   __endasm;
 }
 

arch/z80/src/z8/z8_irq.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/z80/src/z8/z8_irq.c
  *
- *   Copyright (C) 2008-2009 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2008-2009, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -86,7 +86,8 @@ void up_irqinitialize(void)
  * Name: up_irq_save
  *
  * Description:
- *   Disable all interrupts; return previous interrupt state
+ *   Disable all interrupts; return previous interrupt state.
+ *   REVISIT:  Doen't TDI() do all of this?
  *
  ****************************************************************************/
 
@@ -123,12 +124,39 @@ void up_irq_restore(irqstate_t flags)
 
   if ((flags & 0x80) != 0)
     {
-      /* The IRQE bit was set, re-enable interrupts */
+      /* The IRQE bit was set, re-enable interrupts.
+       * REVISIT: Could not RI() so all of this?
+       */
 
       EI();
     }
 }
 
+/****************************************************************************
+ * Name: up_irq_enable
+ *
+ * Description:
+ *   Enable all interrupts; return previous interrupt state
+ *
+ ****************************************************************************/
+
+irqstate_t up_irq_enable(void)
+{
+  /* Bit 7 (IRQE) of the IRQCTL register determines if interrupts were
+   * enabled when this function was called.
+   */
+
+  register irqstate_t retval = getreg8(IRQCTL);
+
+  /* Enable interrupts */
+
+  EI();
+
+  /* Return the previous interrupt state */
+
+  return retval;
+}
+
 /****************************************************************************
  * Name: up_disable_irq
  *

arch/z80/src/z80/z80_irq.c

@@ -1,7 +1,8 @@
 /****************************************************************************
  * arch/z80/src/z80/z80_irq.c
  *
- *   Copyright (C) 2007-2009, 2011-2012 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011-2012, 2018 Gregory Nutt. All rights
+ *     reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -69,11 +70,11 @@ volatile chipreg_t *g_current_regs;
 irqstate_t up_irq_save(void) __naked
 {
   __asm
-	ld	a, i		; AF Parity bit holds interrupt state
+	ld		a, i	; AF Parity bit holds interrupt state
-	di			; Interrupts are disabled
+	di				; Interrupts are disabled
 	push	af		; Return AF in HL
-	pop	hl		;
+	pop		hl		;
-	ret			;
+	ret				;
   __endasm;
 }
 
@@ -88,14 +89,33 @@ irqstate_t up_irq_save(void) __naked
 void up_irq_restore(irqstate_t flags) __naked
 {
   __asm
-	di			; Assume disabled
+	di				; Assume disabled
-	pop	hl		; HL = return address
+	pop		hl		; HL = return address
-	pop	af		; AF Parity bit holds interrupt state
+	pop		af		; AF Parity bit holds interrupt state
-	jp	po, statedisable
+	jp		po, statedisable
 	ei
 statedisable:
 	push	af		; Restore stack
 	push	hl		;
-	ret			; and return
+	ret				; and return
+  __endasm;
+}
+
+/****************************************************************************
+ * Name: up_irq_enable
+ *
+ * Description:
+ *   Enable all interrupts; return previous interrupt state
+ *
+ ****************************************************************************/
+
+irqstate_t up_irq_enable(void) __naked
+{
+  __asm
+	ld		a, i	; AF Parity bit holds interrupt state
+	ei				; Interrupts are enabled
+	push	af		; Return AF in HL
+	pop		hl		;
+	ret				;
   __endasm;
 }