stm32: Add STM32H5 support for sleep mode.

Update rtc, machine and powerctrl drivers to support STM32H5 sleep
modes. This makes RTC alarm wakeup working from lightsleep() and
deepsleep().

Changes:
- Determine start reason for machine.reset_cause() in modmachine.c.
- Add proper interrupt clear code in rtc.c.
- Add wakeup functionality in powerctrl_enter_stop_mode(). Remember
  and restore voltage scaling level. Restart HSI48 if it was on before
  entering sleep mode.
- Clear DBGMCU_CR in SystemClock_Config() as for other variants.
  Otherwise debug flags prevent entering sleep mode.

Implementation Notes:
- rtc.c: EXTI_RTSTR1 bits are not present for H5. Code sequence from
  G0/G4/L4/WB/WL would be invalid. RTSTR is only defined for external
  (GPIO) interrupts. Maybe this is also true for other STM32 variants.
- powerctrl_enter_stop_mode() uses complicated, nested conditionals
  to select STM32 variants. To make code slightly better readable,
  comment have been added. A non-nested, #if/#elif sequence would
  make the code more readable. I leave this to the original authors.

Signed-off-by: Rene Straub <rene@see5.ch>

1 files changed, 4 insertions, 0 deletions

diff --git a/ports/stm32/powerctrlboot.c b/ports/stm32/powerctrlboot.c
index c7802a558..31dae527c 100644
--- a/ports/stm32/powerctrlboot.c
+++ b/ports/stm32/powerctrlboot.c
@@ -298,6 +298,10 @@ void SystemClock_Config(void) {
     LL_RCC_SetUSBClockSource(LL_RCC_USB_CLKSOURCE_PLL3Q);
 
     #endif
+
+    #ifdef NDEBUG
+    DBGMCU->CR = 0;
+    #endif
 }
 
 #elif defined(STM32L0)