HAL_ChibiOS: added IWDG watchdog support

this resets the MCU if the main loop stops for 1 second

libraries/AP_HAL_ChibiOS/HAL_ChibiOS_Class.cpp

@@ -26,6 +26,7 @@
 #include "sdcard.h"
 #include "hwdef/common/usbcfg.h"
 #include "hwdef/common/stm32_util.h"
+#include "hwdef/common/watchdog.h"
 
 #include <hwdef.h>
 
@@ -201,6 +202,9 @@ static void main_loop()
      */
     chThdSetPriority(APM_MAIN_PRIORITY);
 
+    // setup watchdog to reset if main loop stops
+    stm32_watchdog_init();
+
     while (true) {
         g_callbacks->loop();
 
@@ -217,6 +221,7 @@ static void main_loop()
             hal.scheduler->delay_microseconds(50);
         }
 #endif
+        stm32_watchdog_pat();
     }
     thread_running = false;
 }

libraries/AP_HAL_ChibiOS/hwdef/common/chibios_board.mk

@@ -121,7 +121,8 @@ CSRC += $(HWDEF)/common/stubs.c \
 	   $(HWDEF)/common/malloc.c \
 	   $(HWDEF)/common/hrt.c \
        $(HWDEF)/common/stm32_util.c \
-	   $(HWDEF)/common/bouncebuffer.c
+       $(HWDEF)/common/bouncebuffer.c \
+       $(HWDEF)/common/watchdog.c
 
 ifeq ($(USE_FATFS),yes)
 CSRC += $(HWDEF)/common/posix.c

libraries/AP_HAL_ChibiOS/hwdef/common/watchdog.c

@@ -0,0 +1,48 @@
+/*
+  independent watchdog support
+ */
+
+#include "hal.h"
+#include "watchdog.h"
+
+#ifndef IWDG_BASE
+#if defined(STM32H7)
+#define IWDG_BASE             0x58004800
+#elif defined(STM32F7) || defined(STM32F4) || defined(STM32F1)
+#define IWDG_BASE             0x40003000
+#else
+#error "Unknown IWDG_BASE"
+#endif
+#endif
+
+typedef struct
+{
+  __IO uint32_t KR;   /*!< IWDG Key register,       Address offset: 0x00 */
+  __IO uint32_t PR;   /*!< IWDG Prescaler register, Address offset: 0x04 */
+  __IO uint32_t RLR;  /*!< IWDG Reload register,    Address offset: 0x08 */
+  __IO uint32_t SR;   /*!< IWDG Status register,    Address offset: 0x0C */
+  __IO uint32_t WINR; /*!< IWDG Window register,    Address offset: 0x10 */
+} IWDG_Regs;
+
+#define IWDGD (*(IWDG_Regs *)(IWDG_BASE))
+
+/*
+  setup the watchdog
+ */
+void stm32_watchdog_init(void)
+{
+    // setup for 1s reset
+    IWDGD.KR = 0x5555;
+    IWDGD.PR = 8;
+    IWDGD.RLR = 0xFFF;
+    IWDGD.KR = 0xCCCC;
+}
+
+/*
+  pat the dog, to prevent a reset. If not called for 1s
+  after stm32_watchdog_init() then MCU will reset
+ */
+void stm32_watchdog_pat(void)
+{
+    IWDGD.KR = 0xAAAA;
+}

libraries/AP_HAL_ChibiOS/hwdef/common/watchdog.h

@@ -0,0 +1,20 @@
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+  setup the watchdog
+ */
+void stm32_watchdog_init(void);
+
+/*
+  pat the dog, to prevent a reset. If not called for 1s
+  after stm32_watchdog_init() then MCU will reset
+ */
+void stm32_watchdog_pat(void);
+
+#ifdef __cplusplus
+}
+#endif
+