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drivers: rtc: stm32: avoid potential erroneous readings

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As shadow registers bypass is enabled, an erroneous reading may occur at
each day or second increment. This commit fixes this issue.

Signed-off-by: Johan Lafon <johan.lafon@syslinbit.com>
This commit is contained in:
Johan Lafon 2023-09-11 16:49:11 +02:00 • committed by Fabio Baltieri
commit 9e202e57e9
1 changed files with 13 additions and 4 deletions
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17
drivers/rtc/rtc_ll_stm32.c
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@ -182,10 +182,19 @@ static int rtc_stm32_get_time(const struct device *dev, struct rtc_time *timeptr
uint32_t rtc_date, rtc_time, rtc_subsecond;
/* Read subsecond, time and date registers */
rtc_subsecond = LL_RTC_TIME_GetSubSecond(RTC);
rtc_time = LL_RTC_TIME_Get(RTC);
rtc_date = LL_RTC_DATE_Get(RTC);
do {
/* read date, time and subseconds and relaunch if a day increment occurred
* while doing so as it will result in an erroneous result otherwise
*/
rtc_date = LL_RTC_DATE_Get(RTC);
do {
/* read time and subseconds and relaunch if a second increment occurred
* while doing so as it will result in an erroneous result otherwise
*/
rtc_time = LL_RTC_TIME_Get(RTC);
rtc_subsecond = LL_RTC_TIME_GetSubSecond(RTC);
} while (rtc_time != LL_RTC_TIME_Get(RTC));
} while (rtc_date != LL_RTC_DATE_Get(RTC));
timeptr->tm_year = TM_TO_RTC_OFFSET + __LL_RTC_CONVERT_BCD2BIN(__LL_RTC_GET_YEAR(rtc_date));
/* tm_mon allowed values are 0-11 */