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, 23 insertions, 4 deletions

diff --git a/ports/stm32/powerctrl.c b/ports/stm32/powerctrl.c
index 03224f4d8..1bb66c978 100644
--- a/ports/stm32/powerctrl.c
+++ b/ports/stm32/powerctrl.c
@@ -48,6 +48,8 @@
 #define POWERCTRL_GET_VOLTAGE_SCALING() PWR_REGULATOR_VOLTAGE_SCALE0
 #elif defined(STM32H723xx)
 #define POWERCTRL_GET_VOLTAGE_SCALING() LL_PWR_GetRegulVoltageScaling()
+#elif defined(STM32H5)
+#define POWERCTRL_GET_VOLTAGE_SCALING() LL_PWR_GetRegulVoltageScaling()
 #else
 #define POWERCTRL_GET_VOLTAGE_SCALING()     \
     (((PWR->CSR1 & PWR_CSR1_ACTVOS) && (SYSCFG->PWRCR & SYSCFG_PWRCR_ODEN)) ? \
@@ -797,6 +799,14 @@ void powerctrl_enter_stop_mode(void) {
     HAL_PWREx_EnableFlashPowerDown();
     #endif
 
+    #if defined(STM32H5)
+    // Save RCC CR to re-enable OSCs and PLLs after wake up from low power mode.
+    uint32_t rcc_cr = RCC->CR;
+
+    // Save the current voltage scaling level to restore after exiting low power mode.
+    uint32_t vscaling = POWERCTRL_GET_VOLTAGE_SCALING();
+    #endif
+
     #if defined(STM32H7)
     // Save RCC CR to re-enable OSCs and PLLs after wake up from low power mode.
     uint32_t rcc_cr = RCC->CR;
@@ -837,9 +847,9 @@ void powerctrl_enter_stop_mode(void) {
     while (__HAL_RCC_GET_SYSCLK_SOURCE() != RCC_CFGR_SWS_HSI48) {
     }
 
-    #else
+    #else // defined(STM32F0)
 
-    #if defined(STM32H7)
+    #if defined(STM32H5) || defined(STM32H7)
     // When exiting from Stop or Standby modes, the Run mode voltage scaling is reset to
     // the default VOS3 value. Restore the voltage scaling to the previous voltage scale.
     if (vscaling != POWERCTRL_GET_VOLTAGE_SCALING()) {
@@ -879,7 +889,7 @@ void powerctrl_enter_stop_mode(void) {
     while (LL_RCC_GetSysClkSource() != LL_RCC_SYS_CLKSOURCE_STATUS_PLL1) {
     }
 
-    #else
+    #else // defined(STM32H5)
 
     // enable PLL
     __HAL_RCC_PLL_ENABLE();
@@ -899,7 +909,7 @@ void powerctrl_enter_stop_mode(void) {
     }
     #endif
 
-    #endif
+    #endif // defined(STM32H5)
 
     powerctrl_disable_hsi_if_unused();
 
@@ -912,6 +922,15 @@ void powerctrl_enter_stop_mode(void) {
     }
     #endif
 
+    #if defined(STM32H5)
+    if (rcc_cr & RCC_CR_HSI48ON) {
+        // Enable HSI48.
+        LL_RCC_HSI48_Enable();
+        while (!LL_RCC_HSI48_IsReady()) {
+        }
+    }
+    #endif
+
     #if defined(STM32H7)
     // Enable HSI
     if (rcc_cr & RCC_CR_HSION) {