Move watchdog_trace() into the generic watchdog file

We want this function to be available for all chips, so move it into a
generic place.

The task_disable_irq() from the LM4 version can be left in
watchdog_check(), to keep the watchdog_trace() function generic.

BUG=chrome-os-partner:10145
TEST=build for all boards

Change-Id: I98c60ce5958f1498b84a233ef04290a68a7838c5
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/24397
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

4 files changed, 94 insertions, 44 deletions

diff --git a/chip/lm4/watchdog.c b/chip/lm4/watchdog.c
index 2982c8b217..e86cb15852 100644
--- a/chip/lm4/watchdog.c
+++ b/chip/lm4/watchdog.c
@@ -13,8 +13,6 @@
 #include "gpio.h"
 #include "hooks.h"
 #include "task.h"
-#include "timer.h"
-#include "uart.h"
 #include "util.h"
 #include "watchdog.h"
 
@@ -28,47 +26,6 @@
 
 static uint32_t watchdog_period;     /* Watchdog counter initial value */
 
-/* Watchdog debug trace.  This is triggered if the watchdog has not been
- * reloaded after 1x the timeout period, after 2x the period an hardware reset
- * is triggering. */
-void watchdog_trace(uint32_t excep_lr, uint32_t excep_sp)
-{
-	uint32_t psp;
-	uint32_t *stack;
-
-	/* Do NOT reset the watchdog interrupt here; it will be done in
-	 * watchdog_reload(), or reset will be triggered if we don't call that
-	 * by the next watchdog period.  Instead, de-activate the interrupt in
-	 * the NVIC, so the watchdog trace will only be printed once. */
-	task_disable_irq(LM4_IRQ_WATCHDOG);
-
-	asm("mrs %0, psp":"=r"(psp));
-	if ((excep_lr & 0xf) == 1) {
-		/* we were already in exception context */
-		stack = (uint32_t *)excep_sp;
-	} else {
-		/* we were in task context */
-		stack = (uint32_t *)psp;
-	}
-
-	uart_printf("### WATCHDOG PC=%08x / LR=%08x / pSP=%08x ",
-	            stack[6], stack[5], psp);
-	if ((excep_lr & 0xf) == 1)
-		uart_puts("(exc) ###\n");
-	else
-		uart_printf("(task %d) ###\n", task_from_addr(psp));
-	/* Ensure this debug message is always flushed to the UART */
-	uart_emergency_flush();
-
-	/* If we are blocked in a high priority IT handler, the following debug
-	 * messages might not appear but they are useless in that situation. */
-	timer_print_info();
-	uart_emergency_flush();
-	task_print_list();
-	uart_emergency_flush();
-}
-
-
 void IRQ_HANDLER(LM4_IRQ_WATCHDOG)(void) __attribute__((naked));
 void IRQ_HANDLER(LM4_IRQ_WATCHDOG)(void)
 {
@@ -80,8 +37,18 @@ void IRQ_HANDLER(LM4_IRQ_WATCHDOG)(void)
 		      * R0=LR so we can pass it to task_resched_if_needed. */
 		     "push {r0, lr}\n"
 		     "bl watchdog_trace\n"
+		      /* Do NOT reset the watchdog interrupt here; it will
+		       * be done in watchdog_reload(), or reset will be
+		       * triggered if we don't call that by the next watchdog
+		       * period.  Instead, de-activate the interrupt in the
+		       * NVIC, so the watchdog trace will only be printed
+		       * once.
+		       */
+		     "mov r0, %[irq]\n"
+		     "bl task_disable_irq\n"
 		     "pop {r0, lr}\n"
-		     "b task_resched_if_needed\n");
+		     "b task_resched_if_needed\n"
+			: : [irq] "i" (LM4_IRQ_WATCHDOG));
 }
 const struct irq_priority IRQ_BUILD_NAME(prio_, LM4_IRQ_WATCHDOG, )
 	__attribute__((section(".rodata.irqprio")))
diff --git a/chip/stm32/watchdog.c b/chip/stm32/watchdog.c
index da6079ac29..1fd84b2f43 100644
--- a/chip/stm32/watchdog.c
+++ b/chip/stm32/watchdog.c
@@ -34,6 +34,39 @@ void watchdog_reload(void)
 }
 
 
+/**
+ * Chcek if a watchdog interrupt needs to be reported.
+ *
+ * If so, this function should call watchdog_trace()
+ *
+ * @param excep_lr	Value of lr to indicate caller return
+ * @param excep_sp	Value of sp to indicate caller task id
+ */
+void watchdog_check(uint32_t excep_lr, uint32_t excep_sp)
+{
+	/* This is not actually called for now, since we reset instead */
+}
+
+
+void IRQ_HANDLER(STM32_IRQ_WWDG)(void) __attribute__((naked));
+void IRQ_HANDLER(STM32_IRQ_WWDG)(void)
+{
+	/* Naked call so we can extract raw LR and SP */
+	asm volatile("mov r0, lr\n"
+		     "mov r1, sp\n"
+		     /* Must push registers in pairs to keep 64-bit aligned
+		      * stack for ARM EABI.  This also conveninently saves
+		      * R0=LR so we can pass it to task_resched_if_needed. */
+		     "push {r0, lr}\n"
+		     "bl watchdog_check\n"
+		     "pop {r0, lr}\n"
+		     "b task_resched_if_needed\n");
+}
+const struct irq_priority IRQ_BUILD_NAME(prio_, STM32_IRQ_WWDG, )
+	__attribute__((section(".rodata.irqprio")))
+		= {STM32_IRQ_WWDG, 0}; /* put the watchdog at the highest
+					    priority */
+
 int watchdog_init(void)
 {
 	uint32_t watchdog_period;
diff --git a/core/cortex-m/watchdog.c b/core/cortex-m/watchdog.c
index e0a58953fb..3ad89e94ab 100644
--- a/core/cortex-m/watchdog.c
+++ b/core/cortex-m/watchdog.c
@@ -5,10 +5,48 @@
 
 /* Watchdog common code */
 
+#include "board.h"
+#include "common.h"
+#include "config.h"
+#include "registers.h"
+#include "task.h"
 #include "timer.h"
+#include "uart.h"
 #include "watchdog.h"
 
 
+void watchdog_trace(uint32_t excep_lr, uint32_t excep_sp)
+{
+	uint32_t psp;
+	uint32_t *stack;
+
+	asm("mrs %0, psp" : "=r"(psp));
+	if ((excep_lr & 0xf) == 1) {
+		/* we were already in exception context */
+		stack = (uint32_t *)excep_sp;
+	} else {
+		/* we were in task context */
+		stack = (uint32_t *)psp;
+	}
+
+	uart_printf("### WATCHDOG PC=%08x / LR=%08x / pSP=%08x ",
+		    stack[6], stack[5], psp);
+	if ((excep_lr & 0xf) == 1)
+		uart_puts("(exc) ###\n");
+	else
+		uart_printf("(task %d) ###\n", task_from_addr(psp));
+	/* Ensure this debug message is always flushed to the UART */
+	uart_emergency_flush();
+
+	/* If we are blocked in a high priority IT handler, the following debug
+	 * messages might not appear but they are useless in that situation. */
+	timer_print_info();
+	uart_emergency_flush();
+	task_print_list();
+	uart_emergency_flush();
+}
+
+
 /* Low priority task to reload the watchdog */
 void watchdog_task(void)
 {
diff --git a/include/watchdog.h b/include/watchdog.h
index b4d0a1e2f6..46f3b996d7 100644
--- a/include/watchdog.h
+++ b/include/watchdog.h
@@ -20,6 +20,18 @@
  * more than 2 watchdog periods since watchdog_reload() has been called. */
 int watchdog_init(void);
 
+/**
+ * Display a trace with information about an expired watchdog timer
+ *
+ * This shows the location in the code where the expiration happened.
+ * Usually this helps locate a loop which is blocking execution of the
+ * watchdog task.
+ *
+ * @param excep_lr	Value of lr to indicate caller return
+ * @param excep_sp	Value of sp to indicate caller task id
+ */
+void watchdog_trace(uint32_t excep_lr, uint32_t excep_sp);
+
 /* Reload the watchdog counter */
 void watchdog_reload(void);