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rtc: stm32: fix issues of stm32_rtc_valid_alrm function

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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@foss.st.com>
Link: https://lore.kernel.org/r/20230705174357.353616-7-valentin.caron@foss.st.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Valentin Caron 2023-07-05 19:43:56 +02:00 committed by Alexandre Belloni
parent fb9a7e5360
commit 46828a5f89
1 changed files with 33 additions and 28 deletions
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61
drivers/rtc/rtc-stm32.c
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@ -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 {
@ -427,40 +430,42 @@ 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);
return -EINVAL;
/*
* 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;
}
/* 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)
@ -471,17 +476,17 @@ 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) &