LM32: Fix implementation of up_irq_save() and up_irq_restore()

arch/misoc/include/lm32/irq.h

@@ -82,10 +82,11 @@
 #define REG_X29_NDX   29     /* General-purpose/return address */
 #define REG_X30_NDX   30     /* Exception address */
 #define REG_X31_NDX   31     /* Breakpoint address */
+#define REG_X32_NDX   32     /* Reg IE */
 
 /* Interrupt Context register */
 
-#define XCPTCONTEXT_REGS  32
+#define XCPTCONTEXT_REGS  33
 #define XCPTCONTEXT_SIZE  (4 * XCPTCONTEXT_REGS)
 
 #ifdef __ASSEMBLY__
@@ -121,6 +122,7 @@
 #  define REG_X29     (4*REG_X29_NDX)
 #  define REG_X30     (4*REG_X30_NDX)
 #  define REG_X31     (4*REG_X31_NDX)
+#  define REG_INT_CTX (4*REG_X32_NDX)
 #else
 #  define REG_X0       REG_X0_NDX
 #  define REG_X1       REG_X1_NDX
@@ -154,6 +156,7 @@
 #  define REG_X29      REG_X29_NDX
 #  define REG_X30      REG_X30_NDX
 #  define REG_X31      REG_X31_NDX
+#  define REG_INT_CTX  REG_X32_NDX
 #endif
 
 /* Register aliases */
@@ -176,6 +179,8 @@
 #define REG_A6         REG_X7
 #define REG_A7         REG_X8
 
+#define REG_IE         REG_INT_CTX
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/

arch/misoc/src/lm32/lm32_doirq.c

@@ -58,9 +58,7 @@
 uint32_t *lm32_doirq(int irq, uint32_t *regs)
 {
   board_autoled_on(LED_INIRQ);
-#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.
    *

arch/misoc/src/lm32/lm32_initialstate.c

@@ -99,6 +99,10 @@ void up_initial_state(struct tcb_s *tcb)
 
   xcp->regs[REG_EPC]     = (uint32_t)tcb->start;
 
+  /* Initial state of IE:  Interrupts enabled */
+
+  xcp->regs[REG_INT_CTX] = 1;
+
   /* If this task is running PIC, then set the PIC base register to the
    * address of the allocated D-Space region.
    */

arch/misoc/src/lm32/lm32_irq.c

@@ -69,7 +69,7 @@ void lm32_irq_initialize(void)
 
   g_current_regs = NULL;
 
-  /* Enable interrupt */
+  /* Enable interrupts */
 
   irq_setie(1);
 }
@@ -77,15 +77,22 @@ void lm32_irq_initialize(void)
 irqstate_t up_irq_save(void)
 {
   irqstate_t flags;
-  irq_setie(0);
 
-#warning Return value MUST be the previous IE value.  Returning 1 will not work.
-  return 1;
+  /* Get the previous value of IE */
+
+  flags = irq_getie();
+
+  /* Disable interrupts and return the previous interrupt state */
+
+  irq_setie(0);
+  return flags;
 }
 
 void up_irq_restore(irqstate_t flags)
 {
-  irq_setie(1);
+  /* Restore the interrupt state returned by up_save_irq() */
+
+  irq_setie(flags);
 }
 
 /****************************************************************************
@@ -99,8 +106,13 @@ void up_irq_restore(irqstate_t flags)
 void up_disable_irq(int irq)
 {
   irqstate_t flags;
-  flags = irq_getmask();
-  flags &= ~(1 <<irq);
+
+  DEBUGASSERT(irq >= 0 && irq < NR_IRQS);
+
+  /* Disable interrupts by clearing the bit that corresponds to the irq */
+
+  flags  = irq_getmask();
+  flags &= ~(1 << irq);
   irq_setmask(flags);
 }
 
@@ -115,7 +127,11 @@ void up_disable_irq(int irq)
 void up_enable_irq(int irq)
 {
   irqstate_t flags;
-  flags = irq_getmask();
+  DEBUGASSERT(irq >= 0 && irq < NR_IRQS);
+
+  /* Enable interrupts by setting the bit that corresponds to the irq */
+
+  flags  = irq_getmask();
   flags |= (1 << irq);
   irq_setmask(flags);
 }

arch/misoc/src/lm32/lm32_swint.c

@@ -326,5 +326,6 @@ uint32_t *lm32_swint(int irq, FAR void *context)
    */
 
   g_current_regs = NULL;
+
   return regs;
 }

arch/misoc/src/lm32/lm32_vectors.S

@@ -151,7 +151,7 @@ _do_reset:
 	bi      os_start
 
 .save_all:
-	addi    sp, sp, -132
+	addi    sp, sp, -136
 	sw      (sp+REG_X0), r0
 	sw      (sp+REG_X1), r1
 	sw      (sp+REG_X2), r2
@@ -190,11 +190,14 @@ _do_reset:
 
 	/* ra needs to be moved from initial stack location */
 
-	lw      r1, (sp+ 132)
+	lw      r1, (sp+ 136)
 	sw      (sp+REG_RA), r1
 
-	/* the 2nd argument is the regs pointer */
+	/* get IE/REG_INT_CTX */
+	rcsr	r1, IE
+	sw	(sp+REG_INT_CTX), r1
 
+	/* the 2nd argument is the regs pointer */
 	addi    r2, sp, 0
 	ret
 
@@ -231,8 +234,10 @@ _do_reset:
 	lw      r29,  (r1+REG_RA)
 	lw      r30,  (r1+REG_EA)
 	lw      r31,  (r1+REG_BA)
+	lw	r1, (r1+REG_INT_CTX)
+	wcsr	IE, r1
 	lw      r1,  (r1+REG_X1)
-	addi    sp, sp, 132
+	addi    sp, sp, 136
 	eret
 
 	/* This global variable is unsigned long g_idle_topstack and is