ite: Watchdog module added

Watchdog module added. Off by default because of following limitations:
- When programming, the WD fires, and programming fails. For now, you
have to program twice.

BRANCH=none
BUG=chrome-os-partner:23575
TEST=Manually wrote in a while(1); and made sure watchdog warning
triggers first, prints IPC register, and then soon after the watchdog
timer resets the chip.

Signed-off-by: Alec Berg <alecaberg@chromium.org>
Change-Id: Ia83f58f3ae108f755d2f139ada22a22e2fbdc2fa
Reviewed-on: https://chromium-review.googlesource.com/177397
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

3 files changed, 107 insertions, 0 deletions

diff --git a/chip/it83xx/hwtimer.c b/chip/it83xx/hwtimer.c
index cf4de26be8..3493843adc 100644
--- a/chip/it83xx/hwtimer.c
+++ b/chip/it83xx/hwtimer.c
@@ -13,6 +13,7 @@
 #include "task.h"
 #include "timer.h"
 #include "util.h"
+#include "watchdog.h"
 
 /* 128us (2^7 us) between 2 ticks */
 #define TICK_INTERVAL_LOG2  7
@@ -64,6 +65,11 @@ void __hw_clock_source_set(uint32_t ts)
 
 static void __hw_clock_source_irq(void)
 {
+#ifdef CONFIG_WATCHDOG
+	/* Determine interrupt number. */
+	int irq = IT83XX_INTC_IVCT3 - 16;
+#endif
+
 	/*
 	 * If this is a SW interrupt, then process the timers, but don't
 	 * increment the time_us.
@@ -73,6 +79,18 @@ static void __hw_clock_source_irq(void)
 		return;
 	}
 
+#ifdef CONFIG_WATCHDOG
+	/*
+	 * Both the external timer for the watchdog warning and the HW timer
+	 * go through this irq. So, if this interrupt was caused by watchdog
+	 * warning timer, then call that function.
+	 */
+	if (irq == IT83XX_IRQ_EXT_TIMER3) {
+		watchdog_warning_irq();
+		return;
+	}
+#endif
+
 	/* clear interrupt status */
 	task_clear_pending_irq(IT83XX_IRQ_TMR_B0);
 
diff --git a/chip/it83xx/watchdog.c b/chip/it83xx/watchdog.c
new file mode 100644
index 0000000000..d22a3da538
--- /dev/null
+++ b/chip/it83xx/watchdog.c
@@ -0,0 +1,83 @@
+/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* Watchdog driver */
+
+#include "common.h"
+#include "cpu.h"
+#include "hooks.h"
+#include "panic.h"
+#include "registers.h"
+#include "task.h"
+#include "watchdog.h"
+
+/*
+ * We use timer3 to trigger an interrupt just before the watchdog timer
+ * will fire so that we can capture important state information before
+ * being reset.
+ */
+
+/* Magic value to tickle the watchdog register. */
+#define ITE83XX_WATCHDOG_MAGIC_WORD  0x5C
+
+void watchdog_warning_irq(void)
+{
+	/* clear interrupt status */
+	task_clear_pending_irq(IT83XX_IRQ_EXT_TIMER3);
+
+	/* Reset warning timer (timer 3). */
+	IT83XX_ETWD_ET3CTRL = 0x03;
+
+	panic_printf("Pre-watchdog warning! IPC: %08x\n", get_ipc());
+}
+
+void watchdog_reload(void)
+{
+	/* Reset warning timer (timer 3). */
+	IT83XX_ETWD_ET3CTRL = 0x03;
+
+	/* Restart (tickle) watchdog timer. */
+	IT83XX_ETWD_EWDKEYR = ITE83XX_WATCHDOG_MAGIC_WORD;
+}
+DECLARE_HOOK(HOOK_TICK, watchdog_reload, HOOK_PRIO_DEFAULT);
+
+int watchdog_init(void)
+{
+	/* Unlock access to watchdog registers. */
+	IT83XX_ETWD_ETWCFG = 0x00;
+
+	/* Set timer 3 and WD timer to use 1.024kHz clock. */
+	IT83XX_ETWD_ET3PSR = 0x01;
+	IT83XX_ETWD_ET1PSR = 0x01;
+
+	/* Set WDT key match enabled and WDT clock to use ET1PSR. */
+	IT83XX_ETWD_ETWCFG = 0x30;
+
+	/* Specify that watchdog cannot be stopped. */
+	IT83XX_ETWD_ETWCTRL = 0x00;
+
+	/* Set timer 3 load value to 1024 (~1.05 seconds). */
+	IT83XX_ETWD_ET3CNTLH2R = 0x00;
+	IT83XX_ETWD_ET3CNTLHR = 0x04;
+	IT83XX_ETWD_ET3CNTLLR = 0x00;
+
+	/* Enable interrupt on timer 3 expiration. */
+	task_enable_irq(IT83XX_IRQ_EXT_TIMER3);
+
+	/* Start timer 3. */
+	IT83XX_ETWD_ET3CTRL = 0x03;
+
+	/* Start timer 1 (must be started for watchdog timer to run). */
+	IT83XX_ETWD_ET1CNTLLR = 0x00;
+
+	/* Set watchdog timer to ~1.3 seconds. Writing CNTLL starts timer. */
+	IT83XX_ETWD_EWDCNTLHR = 0x05;
+	IT83XX_ETWD_EWDCNTLLR = 0x00;
+
+	/* Lock access to watchdog registers. */
+	IT83XX_ETWD_ETWCFG = 0x3f;
+
+	return EC_SUCCESS;
+}
diff --git a/include/watchdog.h b/include/watchdog.h
index 02c603ca40..1981e3ce10 100644
--- a/include/watchdog.h
+++ b/include/watchdog.h
@@ -31,6 +31,12 @@ int watchdog_init(void);
  */
 void watchdog_trace(uint32_t excep_lr, uint32_t excep_sp);
 
+/**
+ * Watchdog has not been tickled recently warning. This function should be
+ * called when the watchdog is close to firing.
+ */
+void watchdog_warning_irq(void);
+
 /* Reload the watchdog counter */
 #ifdef CONFIG_WATCHDOG
 void watchdog_reload(void);