djsundog
/
circuitpython
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Fix STM RTC read so it's atomic. 

Fixes #3376
This commit is contained in:
Scott Shawcroft 2020-10-12 17:43:13 -07:00
parent 699f19f44a
commit a0e5e961c5
No known key found for this signature in database
GPG Key ID: 0DFD512649C052DA
1 changed files with 17 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
ports/stm/supervisor/port.c
View File

@ -190,6 +190,7 @@ safe_mode_t port_init(void) {
_hrtc.Init.OutPut = RTC_OUTPUT_DISABLE;
HAL_RTC_Init(&_hrtc);
HAL_RTCEx_EnableBypassShadow(&_hrtc);
HAL_NVIC_EnableIRQ(RTC_Alarm_IRQn);
// Turn off SysTick
@ -328,9 +329,23 @@ volatile uint32_t cached_date = 0;
volatile uint32_t seconds_to_minute = 0;
volatile uint32_t cached_hours_minutes = 0;
uint64_t port_get_raw_ticks(uint8_t* subticks) {
uint32_t subseconds = rtc_clock_frequency - (uint32_t)(RTC->SSR);
// Disable IRQs to ensure we read all of the RTC registers as close in time as possible. Read
// SSR twice to make sure we didn't read across a tick.
__disable_irq();
uint32_t first_ssr = (uint32_t)(RTC->SSR);
uint32_t time = (uint32_t)(RTC->TR & RTC_TR_RESERVED_MASK);
uint32_t date = (uint32_t)(RTC->DR & RTC_DR_RESERVED_MASK);
uint32_t ssr = (uint32_t)(RTC->SSR);
while (ssr != first_ssr) {
first_ssr = ssr;
time = (uint32_t)(RTC->TR & RTC_TR_RESERVED_MASK);
date = (uint32_t)(RTC->DR & RTC_DR_RESERVED_MASK);
ssr = (uint32_t)(RTC->SSR);
}
__enable_irq();
uint32_t subseconds = rtc_clock_frequency - 1 - ssr;
if (date != cached_date) {
uint32_t year = (uint8_t)((date & (RTC_DR_YT | RTC_DR_YU)) >> 16U);
uint8_t month = (uint8_t)((date & (RTC_DR_MT | RTC_DR_MU)) >> 8U);
@ -349,6 +364,7 @@ uint64_t port_get_raw_ticks(uint8_t* subticks) {
hours = (uint8_t)RTC_Bcd2ToByte(hours);
minutes = (uint8_t)RTC_Bcd2ToByte(minutes);
seconds_to_minute = 60 * (60 * hours + minutes);
cached_hours_minutes = hours_minutes;
}
uint8_t seconds = (uint8_t)(time & (RTC_TR_ST | RTC_TR_SU));
seconds = (uint8_t)RTC_Bcd2ToByte(seconds);