1 files changed, 81 insertions, 5 deletions

diff --git a/chip/mec1322/watchdog.c b/chip/mec1322/watchdog.c
index f46360f152..87533ac571 100644
--- a/chip/mec1322/watchdog.c
+++ b/chip/mec1322/watchdog.c
@@ -5,23 +5,70 @@
 
 /* Watchdog driver */
 
-/*
- * TODO(crosbug.com/p/24107): Use independent timer for warning before watchdog
- *                            timer expires.
- */
-
 #include "hooks.h"
 #include "registers.h"
+#include "task.h"
 #include "watchdog.h"
 
+/*
+ * Fire auxiliary timer 50ms before watchdog timer expires. This leaves
+ * some time for debug trace to be printed.
+ */
+#define AUX_TIMER_PERIOD_MS (WATCHDOG_PERIOD_MS - 50)
+
 void watchdog_reload(void)
 {
 	MEC1322_WDG_KICK = 1;
+
+#ifdef CONFIG_WATCHDOG_HELP
+	/* Reload the auxiliary timer */
+	MEC1322_TMR16_CTL(0) &= ~(1 << 5);
+	MEC1322_TMR16_CNT(0) = AUX_TIMER_PERIOD_MS;
+	MEC1322_TMR16_CTL(0) |= 1 << 5;
+#endif
 }
 DECLARE_HOOK(HOOK_TICK, watchdog_reload, HOOK_PRIO_DEFAULT);
 
 int watchdog_init(void)
 {
+#ifdef CONFIG_WATCHDOG_HELP
+	uint32_t val;
+
+	/*
+	 * Watchdog does not warn us before expiring. Let's use a 16-bit
+	 * timer as an auxiliary timer.
+	 */
+
+	/* Stop the auxiliary timer if it's running */
+	MEC1322_TMR16_CTL(0) &= ~(1 << 5);
+
+	/* Enable auxiliary timer */
+	MEC1322_TMR16_CTL(0) |= 1 << 0;
+
+	val = MEC1322_TMR16_CTL(0);
+
+	/* Pre-scale = 48000 -> 1kHz -> Period = 1ms */
+	val = (val & 0xffff) | (47999 << 16);
+
+	/* No auto restart */
+	val &= ~(1 << 3);
+
+	/* Count down */
+	val &= ~(1 << 2);
+
+	MEC1322_TMR16_CTL(0) = val;
+
+	/* Enable interrupt from auxiliary timer */
+	MEC1322_TMR16_IEN(0) |= 1;
+	task_enable_irq(MEC1322_IRQ_TIMER16_0);
+	MEC1322_INT_ENABLE(23) |= 1 << 0;
+	MEC1322_INT_BLK_EN |= 1 << 23;
+
+	/* Load and start the auxiliary timer */
+	MEC1322_TMR16_CNT(0) = AUX_TIMER_PERIOD_MS;
+	MEC1322_TMR16_CNT(0) |= 1 << 5;
+#endif
+
 	/* Set timeout. It takes 1007us to decrement WDG_CNT by 1. */
 	MEC1322_WDG_LOAD = WATCHDOG_PERIOD_MS * 1000 / 1007;
 
@@ -30,3 +77,32 @@ int watchdog_init(void)
 
 	return EC_SUCCESS;
 }
+
+#ifdef CONFIG_WATCHDOG_HELP
+void watchdog_check(uint32_t excep_lr, uint32_t excep_sp)
+{
+	/* Clear status */
+	MEC1322_TMR16_STS(0) |= 1;
+
+	watchdog_trace(excep_lr, excep_sp);
+}
+
+void IRQ_HANDLER(MEC1322_IRQ_TIMER16_0)(void) __attribute__((naked));
+void IRQ_HANDLER(MEC1322_IRQ_TIMER16_0)(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_PRIORITY(MEC1322_IRQ_TIMER16_0)
+	__attribute__((section(".rodata.irqprio")))
+		= {MEC1322_IRQ_TIMER16_0, 0}; /* put the watchdog at the
+						 highest priority */
+#endif