Merge pull request #2214 from rousselk/msp430-fix-intr

Msp430 misc interrupt-related fixes

cpu/msp430-common/include/cpu.h

@@ -40,8 +40,8 @@ extern "C" {
 extern volatile int __inISR;
 extern char __isr_stack[MSP430_ISR_STACK_SIZE];
 
-//#define eINT()  eint()
+/*#define eINT()  eint() */
-//#define dINT()  dint()
+/*#define dINT()  dint() */
 
 inline void __save_context_isr(void)
 {
@@ -125,14 +125,22 @@ inline void __restore_context(unsigned int irqen)
 
 inline void eINT(void)
 {
-    //    puts("+");
+    /*    puts("+"); */
-    eint();
+/*    eint();   // problem with MSPGCC intrinsics? */
+    __asm__ __volatile__("bis  %0, r2" : : "i"(GIE));
+    __asm__ __volatile__("nop");
+       /* this NOP is needed to handle a "delay slot" that all MSP430 MCUs
+          impose silently after messing with the GIE bit, DO NOT REMOVE IT! */
 }
 
 inline void dINT(void)
 {
-    //    puts("-");
+    /*    puts("-"); */
-    dint();
+/*    dint();   // problem with MSPGCC intrinsics? */
+    __asm__ __volatile__("bic  %0, r2" : : "i"(GIE));
+    __asm__ __volatile__("nop");
+       /* this NOP is needed to handle a "delay slot" that all MSP430 MCUs
+          impose silently after messing with the GIE bit, DO NOT REMOVE IT! */
 }
 
 int inISR(void);

cpu/msp430-common/lpm_cpu.c

@@ -33,10 +33,10 @@
 /* Initialise the MSP430 power-saving mechanisms. */
 void lpm_init(void)
 {
-    // nothing to initialize on MSP430s: everything is done by fiddling
+    /* nothing to initialize on MSP430s: everything is done by fiddling
-    //  with 4 bits of the status register (SR).
+       with 4 bits of the status register (SR). */
 
-    // just ensure MCU is fully up and running at start
+    /* just ensure MCU is fully up and running at start */
     lpm_awake();
 }
 
@@ -45,33 +45,44 @@ enum lpm_mode lpm_set(enum lpm_mode target)
 {
     enum lpm_mode last_mode = lpm_get();
 
+    /* ensure that interrupts are enabled before going to sleep,
+       or we're bound to hang our MCU! */
+    if (target != LPM_ON) {
+        if ((__read_status_register() & GIE) == 0) {
+            printf("WARNING: entering low-power mode with interrupts disabled!\n");
+            printf("         Forcing GIE bit to 1!\n\n");
+            __bis_status_register(GIE);
+        }
+    }
+
     switch (target)
     {
     case LPM_ON:
-        // fully running MCU
+        /* fully running MCU */
         __bic_status_register(CPUOFF | OSCOFF | SCG0 | SCG1);
         break;
     case LPM_IDLE:
-        // lightest mode => LPM0 mode of MSP430
+        /* lightest mode => LPM0 mode of MSP430 */
         __bic_status_register(OSCOFF | SCG0 | SCG1);
-        // only stops CPU block
+        /* only stops CPU block */
         __bis_status_register(CPUOFF);
         break;
     case LPM_SLEEP:
-        // mid-level mode => LPM1 mode of MSP430
+        /* mid-level mode => LPM1 mode of MSP430 */
         __bic_status_register(OSCOFF | SCG1);
-        // stops CPU and master clock blocks
+        /* stops CPU and master clock blocks */
         __bis_status_register(CPUOFF | SCG0);
         break;
     case LPM_POWERDOWN:
-        // deep-level mode => LPM3 mode of MSP430
+        /* deep-level mode => LPM3 mode of MSP430 */
         __bic_status_register(OSCOFF);
-        // stops all blocks except auxiliary clock (timers)
+        /* stops all blocks except auxiliary clock (timers) */
         __bis_status_register(CPUOFF | SCG0 | SCG1);
         break;
     case LPM_OFF:
-        // MCU totally down (LPM4), only RESET or NMI can resume execution
+        /* MCU totally down (LPM4), only RESET or NMI can resume execution */
-        __bis_status_register(CPUOFF | OSCOFF | SCG0 | SCG1);  // all blocks off
+        __bis_status_register(CPUOFF | OSCOFF | SCG0 | SCG1);
+                               /* all blocks off */
         break;
     default:
         printf("ERROR: trying to set an invalid low-power mode!\n");
@@ -90,20 +101,20 @@ enum lpm_mode lpm_get(void)
 
     unsigned int current_sr = __read_status_register();
     switch (current_sr & LPM_MASK_SR) {
-    case CPUOFF + OSCOFF + SCG0 + SCG1:   // MSP430's LPM4
+    case CPUOFF + OSCOFF + SCG0 + SCG1:   /* MSP430's LPM4 */
         current_mode = LPM_OFF;
         break;
-    case CPUOFF + SCG0 + SCG1:   // MSP430's LPM3
+    case CPUOFF + SCG0 + SCG1:   /* MSP430's LPM3 */
-    case CPUOFF + SCG1:   // MSP430's LPM2
+    case CPUOFF + SCG1:   /* MSP430's LPM2 */
         current_mode = LPM_POWERDOWN;
         break;
-    case CPUOFF + SCG0:   // MSP430's LPM1
+    case CPUOFF + SCG0:   /* MSP430's LPM1 */
         current_mode = LPM_SLEEP;
         break;
-    case CPUOFF:   // MSP430's LPM1
+    case CPUOFF:   /* MSP430's LPM1 */
         current_mode = LPM_IDLE;
         break;
-    case 0:   // MSP430 active
+    case 0:   /* MSP430 active */
         current_mode = LPM_ON;
         break;
     }
@@ -114,7 +125,7 @@ enum lpm_mode lpm_get(void)
 /* resume the MSP430 MCU */
 inline void lpm_awake(void)
 {
-    // disable all power savings mechanisms
+    /* disable all power savings mechanisms */
     __bic_status_register(CPUOFF | OSCOFF | SCG0 | SCG1);
 }
 

cpu/msp430-common/msp430-main.c

@@ -160,6 +160,7 @@ splhigh_(void)
     int sr;
     asmv("mov r2, %0" : "=r"(sr));
     asmv("bic %0, r2" : : "i"(GIE));
+    asmv("nop");
     return sr & GIE;        /* Ignore other sr bits. */
 }
 /*---------------------------------------------------------------------------*/
@@ -169,8 +170,10 @@ splhigh_(void)
 void
 splx_(int sr)
 {
+    sr &= GIE;
     /* If GIE was set, restore it. */
     asmv("bis %0, r2" : : "r"(sr));
+    asmv("nop");
 }
 /*---------------------------------------------------------------------------*/