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ACPI: TAD: RTC: Refine timer value computations and checks

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Since rtc_tm_to_ktime() may overflow for large RTC time values and
full second granularity is sufficient in timer value computations
in acpi_tad_rtc_set_alarm() and acpi_tad_rtc_read_alarm(), use
rtc_tm_to_time64() instead of that function, which also allows the
computations to be simplified.

Moreover, U32_MAX is a special "timer disabled" value, so make
acpi_tad_rtc_set_alarm() reject it when attempting to program the
alarm timers.

Fixes: 7572dcabe3 ("ACPI: TAD: Add alarm support to the RTC class device interface")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://patch.msgid.link/3414608.aeNJFYEL58@rafael.j.wysocki
This commit is contained in:
Rafael J. Wysocki 2026-04-22 17:26:49 +02:00
parent 77dd14ab1b
commit e0d2190104
1 changed files with 3 additions and 5 deletions
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8
drivers/acpi/acpi_tad.c
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@ -680,9 +680,8 @@ static int acpi_tad_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
acpi_tad_rt_to_tm(&rt, &tm_now);
value = ktime_divns(ktime_sub(rtc_tm_to_ktime(t->time),
rtc_tm_to_ktime(tm_now)), NSEC_PER_SEC);
if (value <= 0 || value > U32_MAX)
value = rtc_tm_to_time64(&t->time) - rtc_tm_to_time64(&tm_now);
if (value <= 0 || value >= U32_MAX)
return -EINVAL;
}
@ -745,8 +744,7 @@ static int acpi_tad_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *t)
if (retval != ACPI_TAD_WAKE_DISABLED) {
t->enabled = 1;
t->time = rtc_ktime_to_tm(ktime_add_ns(rtc_tm_to_ktime(tm_now),
(u64)retval * NSEC_PER_SEC));
rtc_time64_to_tm(rtc_tm_to_time64(&tm_now) + retval, &t->time);
} else {
t->enabled = 0;
t->time = tm_now;