4 files changed, 58 insertions, 1 deletions

diff --git a/firmware/target/arm/imx233/icoll-imx233.c b/firmware/target/arm/imx233/icoll-imx233.c
index e42e0f3291..e23af602db 100644
--- a/firmware/target/arm/imx233/icoll-imx233.c
+++ b/firmware/target/arm/imx233/icoll-imx233.c
@@ -146,6 +146,7 @@ struct imx233_icoll_irq_info_t imx233_icoll_get_irq_info(int src)
 
 static void do_irq_stat(void)
 {
+    imx233_keep_alive();
     static unsigned counter = 0;
     if(counter++ >= HZ)
     {
@@ -180,6 +181,8 @@ void irq_handler(void)
     asm volatile(
         "sub    lr, lr, #4               \n" /* Create return address */
         "stmfd  sp!, { r0-r5, r12, lr }  \n" /* Save what gets clobbered */
+        "ldr    r5, =0x8001c290          \n" /* Save pointer to instruction */
+        "str    lr, [r5]                 \n" /* in HW_DIGCTL_SCRATCH0 */
         "ldr    r4, =0x80000000          \n" /* Read HW_ICOLL_VECTOR  */
         "ldr    r0, [r4]                 \n" /* and notify as side-effect */
         "mrs    lr, spsr                 \n" /* Save SPSR_irq */
diff --git a/firmware/target/arm/imx233/system-imx233.c b/firmware/target/arm/imx233/system-imx233.c
index b25ccb5c47..5298f7cff9 100644
--- a/firmware/target/arm/imx233/system-imx233.c
+++ b/firmware/target/arm/imx233/system-imx233.c
@@ -45,6 +45,55 @@
 #include "fmradio_i2c.h"
 #include "powermgmt-imx233.h"
 
+#define WATCHDOG_HW_DELAY   (10 * HZ)
+#define WATCHDOG_SW_DELAY   (5 * HZ)
+
+static void woof_woof(void)
+{
+    /* stop hadrware watchdog, we catched the error */
+    imx233_rtc_enable_watchdog(false);
+    uint32_t pc = HW_DIGCTL_SCRATCH0;
+    /* write a "SWI #0xdead" instruction at the faulty instruction so that it
+     * will trigger a proper backtrace */
+    *(uint32_t *)pc = 0xef00dead;
+    commit_discard_idcache();
+}
+
+static void good_dog(void)
+{
+    imx233_rtc_reset_watchdog(WATCHDOG_HW_DELAY * 1000 / HZ); /* ms */
+    imx233_rtc_enable_watchdog(true);
+    imx233_timrot_setup(TIMER_WATCHDOG, false, WATCHDOG_SW_DELAY * 1000 / HZ,
+        BV_TIMROT_TIMCTRLn_SELECT__1KHZ_XTAL, BV_TIMROT_TIMCTRLn_PRESCALE__DIV_BY_1,
+        false, &woof_woof);
+    imx233_timrot_set_priority(TIMER_WATCHDOG, ICOLL_PRIO_WATCHDOG);
+}
+
+void imx233_keep_alive(void)
+{
+    /* setting up a timer is not exactly a cheap operation so only do so
+     * every second */
+    static uint32_t last_alive = 0;
+    if(imx233_us_elapsed(last_alive, 1000000))
+    {
+        good_dog();
+        last_alive = HW_DIGCTL_MICROSECONDS;
+    }
+}
+
+static void watchdog_init(void)
+{
+    /* setup two mechanisms:
+     * - hardware watchdog to reset the player after 10 seconds
+     * - software watchdog using a timer to panic after 5 seconds
+     * The hardware mechanism ensures reset when the player is completely
+     * dead and it actually resets the whole chip. On the contrary, the software
+     * mechanism allows partial recovery by panicing and printing (maybe) useful
+     * information, it uses a dedicated timer with the highest level of interrupt
+     * priority so it works even if the player is stuck in IRQ context */
+    good_dog();
+}
+
 void imx233_chip_reset(void)
 {
 #if IMX233_SUBTARGET >= 3700
@@ -60,7 +109,6 @@ void system_reboot(void)
 
     disable_irq();
 
-    /* use watchdog to reset */
     imx233_chip_reset();
     while(1);
 }
@@ -134,6 +182,8 @@ void system_init(void)
     imx233_power_init();
     imx233_i2c_init();
     imx233_powermgmt_init();
+    /* setup watchdog */
+    watchdog_init();
 
     /* make sure auto-slow is disable now, we don't know at which frequency we
      * are running and auto-slow could violate constraints on {xbus,hbus} */
diff --git a/firmware/target/arm/imx233/system-target.h b/firmware/target/arm/imx233/system-target.h
index 33e8f12265..6272cf7a85 100644
--- a/firmware/target/arm/imx233/system-target.h
+++ b/firmware/target/arm/imx233/system-target.h
@@ -68,4 +68,7 @@ void usb_remove_int(void);
 
 bool dbg_hw_target_info(void);
 
+/* for watchdog */
+void imx233_keep_alive(void);
+
 #endif /* SYSTEM_TARGET_H */
diff --git a/firmware/target/arm/imx233/timrot-imx233.h b/firmware/target/arm/imx233/timrot-imx233.h
index f1a7780f34..e33de39390 100644
--- a/firmware/target/arm/imx233/timrot-imx233.h
+++ b/firmware/target/arm/imx233/timrot-imx233.h
@@ -32,6 +32,7 @@ enum
 {
     TIMER_TICK, /* for tick task */
     TIMER_USER, /* for user timer */
+    TIMER_WATCHDOG, /* for watchdog */
 };
 
 struct imx233_timrot_info_t