Merge branch 'wdt' into 'master'

Watchdog timer implementation
-----------------------------

Enable watchdog timer on boot. Add FreeRTOS task to clear the timer. 
Watchdog expires after 2.7 seconds, and is cleared every 2 seconds.

See merge request !172

epicardium/main.c

@@ -104,6 +104,9 @@ int main(void)
 		abort();
 	}
 
+	/* Watchdog petting */
+	watchdog_clearer_init();
+
 	LOG_DEBUG("startup", "Starting FreeRTOS ...");
 	vTaskStartScheduler();
 

epicardium/modules/hardware.c

@@ -20,6 +20,7 @@
 #include "rtc.h"
 #include "spi.h"
 #include "trng.h"
+#include "wdt.h"
 
 /*
  * Early init is called at the very beginning and is meant for modules which
@@ -28,6 +29,23 @@
  */
 int hardware_early_init(void)
 {
+	/*
+	 * Watchdog timer
+	 */
+	sys_cfg_wdt_t wdt_cfg = NULL;
+	WDT_Init(MXC_WDT0, wdt_cfg);
+
+	if (WDT_GetResetFlag(MXC_WDT0)) {
+		WDT_ClearResetFlag(MXC_WDT0);
+		LOG_INFO("watchdog", "Reset due to watchdog timeout");
+	}
+
+	WDT_Enable(MXC_WDT0, 1);
+	WDT_SetResetPeriod(
+		MXC_WDT0,
+		WDT_PERIOD_2_27); /* Clocked by PCLK at 50MHz, reset at 2^27 ticks = 2.7 seconds */
+	WDT_EnableReset(MXC_WDT0, 1);
+
 	/*
 	 * I2C bus for onboard peripherals (ie. PMIC, BMA400, BHI160, BME680,
 	 * ...)

epicardium/modules/meson.build

@@ -18,4 +18,5 @@ module_sources = files(
   'stream.c',
   'trng.c',
   'vibra.c',
+  'watchdog.c',
 )

epicardium/modules/modules.h

@@ -35,6 +35,9 @@ int personal_state_enabled();
 /* ---------- PMIC --------------------------------------------------------- */
 void vPmicTask(void *pvParameters);
 
+/* ---------- Watchdog ----------------------------------------------------- */
+void watchdog_clearer_init();
+
 /* Critical battery voltage */
 #define BATTERY_CRITICAL   3.40f
 

epicardium/modules/watchdog.c

+#include "modules/log.h"
+#include "modules/modules.h"
+
+#include "timers.h"
+#include "mxc_sys.h"
+#include "wdt.h"
+
+static TimerHandle_t clearer_timer;
+static StaticTimer_t clearer_timer_buffer;
+#define CLEAR_PERIOD pdMS_TO_TICKS(2000)
+
+static void watchdog_clearer_callback()
+{
+	WDT_ResetTimer(MXC_WDT0);
+}
+
+void watchdog_clearer_init()
+{
+	clearer_timer = xTimerCreateStatic(
+		"watchdog_clearer_timer",
+		CLEAR_PERIOD,
+		pdTRUE,
+		NULL,
+		watchdog_clearer_callback,
+		&clearer_timer_buffer
+	);
+	xTimerStart(clearer_timer, 0);
+}