Add reset support, minor fixes

ports/stm32f4/common-hal/microcontroller/__init__.c

@@ -37,11 +37,13 @@
 #include "shared-bindings/microcontroller/Processor.h"
 
 #include "supervisor/filesystem.h"
+#include "supervisor/shared/safe_mode.h"
 
 // This routine should work even when interrupts are disabled. Used by OneWire
 // for precise timing.
 void common_hal_mcu_delay_us(uint32_t delay) {
-    //NRFX_DELAY_US(delay);
+  //TODO: implement equivalent of mp_hal_delay_us(delay);
+  //this is fairly annoying in the STM32 HAL
 }
 
 void common_hal_mcu_disable_interrupts() {
@@ -51,12 +53,13 @@ void common_hal_mcu_enable_interrupts() {
 }
 
 void common_hal_mcu_on_next_reset(mcu_runmode_t runmode) {
-    // TODO: see atmel-samd for functionality
+  if(runmode == RUNMODE_SAFE_MODE)
+    safe_mode_on_next_reset(PROGRAMMATIC_SAFE_MODE);
 }
 
 void common_hal_mcu_reset(void) {
-    // filesystem_flush();
-    // NVIC_SystemReset();
+    filesystem_flush();
+    NVIC_SystemReset();
 }
 
 // The singleton microcontroller.Processor object, bound to microcontroller.cpu

ports/stm32f4/mpconfigport.mk

@@ -20,4 +20,5 @@ CIRCUITPY_MINIMAL_BUILD = 1
 	CIRCUITPY_DIGITALIO = 1
 	CIRCUITPY_MICROCONTROLLER = 1
 	CIRCUITPY_BUSIO = 1
+	CIRCUITPY_TIME = 1
 #endif

ports/stm32f4/supervisor/port.c

@@ -69,6 +69,6 @@ uint32_t port_get_saved_word(void) {
     return _ebss;
 }
 
-// void HardFault_Handler(void) {
+void HardFault_Handler(void) {
 
-// }
+}