stm32_rtc_valid_alrm function has some issues :
- arithmetical operations are impossible on BCD values
- "cur_mon + 1" can overflow
- the use case with the next month, the same day/hour/minutes went wrong
To solve that, we prefer to use timestamp comparison.
e.g. : On 5 Dec. 2021, the alarm limit is 5 Jan. 2022 (+31 days)
On 31 Jan 2021, the alarm limit is 28 Feb. 2022 (+28 days)
Signed-off-by: Valentin Caron <valentin.caron@xxxxxxxxxxx>
---
drivers/rtc/rtc-stm32.c | 61 ++++++++++++++++++++++-------------------
1 file changed, 33 insertions(+), 28 deletions(-)
diff --git a/drivers/rtc/rtc-stm32.c b/drivers/rtc/rtc-stm32.c
index 30c5004d6902..85689192fa7a 100644
--- a/drivers/rtc/rtc-stm32.c
+++ b/drivers/rtc/rtc-stm32.c
@@ -90,6 +90,9 @@
/* Max STM32 RTC register offset is 0x3FC */
#define UNDEF_REG 0xFFFF
+/* STM32 RTC driver time helpers */
+#define SEC_PER_DAY (24 * 60 * 60)
+
struct stm32_rtc;
struct stm32_rtc_registers {
@@ -426,40 +429,42 @@ static int stm32_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
return 0;
}
-static int stm32_rtc_valid_alrm(struct stm32_rtc *rtc, struct rtc_time *tm)
+static int stm32_rtc_valid_alrm(struct device *dev, struct rtc_time *tm)
{
- const struct stm32_rtc_registers *regs = &rtc->data->regs;
- int cur_day, cur_mon, cur_year, cur_hour, cur_min, cur_sec;
- unsigned int tr = readl_relaxed(rtc->base + regs->tr);
- unsigned int dr = readl_relaxed(rtc->base + regs->dr);
-
- cur_day = (dr & STM32_RTC_DR_DATE) >> STM32_RTC_DR_DATE_SHIFT;
- cur_mon = (dr & STM32_RTC_DR_MONTH) >> STM32_RTC_DR_MONTH_SHIFT;
- cur_year = (dr & STM32_RTC_DR_YEAR) >> STM32_RTC_DR_YEAR_SHIFT;
- cur_sec = (tr & STM32_RTC_TR_SEC) >> STM32_RTC_TR_SEC_SHIFT;
- cur_min = (tr & STM32_RTC_TR_MIN) >> STM32_RTC_TR_MIN_SHIFT;
- cur_hour = (tr & STM32_RTC_TR_HOUR) >> STM32_RTC_TR_HOUR_SHIFT;
+ static struct rtc_time now;
+ time64_t max_alarm_time64;
+ int max_day_forward;
+ int next_month;
+ int next_year;
/*
* Assuming current date is M-D-Y H:M:S.
* RTC alarm can't be set on a specific month and year.
* So the valid alarm range is:
* M-D-Y H:M:S < alarm <= (M+1)-D-Y H:M:S
- * with a specific case for December...
*/
- if (((tm->tm_year > cur_year &&
- tm->tm_mon == 0x1 && cur_mon == 0x12) ||
- (tm->tm_year == cur_year &&
- tm->tm_mon <= cur_mon + 1)) &&
- (tm->tm_mday > cur_day ||
- (tm->tm_mday == cur_day &&
- (tm->tm_hour > cur_hour ||
- (tm->tm_hour == cur_hour && tm->tm_min > cur_min) ||
- (tm->tm_hour == cur_hour && tm->tm_min == cur_min &&
- tm->tm_sec >= cur_sec)))))
- return 0;
+ stm32_rtc_read_time(dev, &now);
+
+ /*
+ * Find the next month and the year of the next month.
+ * Note: tm_mon and next_month are from 0 to 11
+ */
+ next_month = now.tm_mon + 1;
+ if (next_month == 12) {
+ next_month = 0;
+ next_year = now.tm_year + 1;
+ } else {
+ next_year = now.tm_year;
+ }
- return -EINVAL;
+ /* Find the maximum limit of alarm in days. */
+ max_day_forward = rtc_month_days(now.tm_mon, now.tm_year)
+ - now.tm_mday
+ + min(rtc_month_days(next_month, next_year), now.tm_mday);
+
+ /* Convert to timestamp and compare the alarm time and its upper limit */
+ max_alarm_time64 = rtc_tm_to_time64(&now) + max_day_forward * SEC_PER_DAY;
+ return rtc_tm_to_time64(tm) <= max_alarm_time64 ? 0 : -EINVAL;
}
static int stm32_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
@@ -470,17 +475,17 @@ static int stm32_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
unsigned int cr, isr, alrmar;
int ret = 0;
- tm2bcd(tm);
-
/*
* RTC alarm can't be set on a specific date, unless this date is
* up to the same day of month next month.
*/
- if (stm32_rtc_valid_alrm(rtc, tm) < 0) {
+ if (stm32_rtc_valid_alrm(dev, tm) < 0) {
dev_err(dev, "Alarm can be set only on upcoming month.\n");
return -EINVAL;
}
+ tm2bcd(tm);
+
alrmar = 0;
/* tm_year and tm_mon are not used because not supported by RTC */
alrmar |= (tm->tm_mday << STM32_RTC_ALRMXR_DATE_SHIFT) &
--
2.25.1
