Some BIOSes, such as the one of the Dell XPS13 9333, wake the system when an alarm goes off without informing the OS. If any of the RTC_IRQMASK bits is set when this happens and hpet is enabled, the alarm is not automatically cleared at resume. As consequence, the user must manually clear the alarm writing 0 to wakealarm before being able to set a new alarm. Ensure this never happens.
Signed-off-by: Gabriele Mazzotta <gabriele....@gmail.com> --- drivers/rtc/rtc-cmos.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c index 1dec52f..62d5b33 100644 --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -900,10 +900,32 @@ static inline int cmos_poweroff(struct device *dev) #ifdef CONFIG_PM_SLEEP +static bool cmos_is_wkalrm_expired(struct device *dev) +{ + struct cmos_rtc *cmos = dev_get_drvdata(dev); + struct rtc_wkalrm alarm; + struct rtc_time now; + time64_t t_now; + time64_t t_expires; + int ret; + + ret = rtc_read_alarm(cmos->rtc, &alarm); + if (ret) { + dev_err(dev, "Could not read alarm: err=%d\n", ret); + return false; + } + t_expires = rtc_tm_to_time64(&alarm.time); + cmos_read_time(dev, &now); + t_now = rtc_tm_to_time64(&now); + + return t_expires <= t_now; +} + static int cmos_resume(struct device *dev) { struct cmos_rtc *cmos = dev_get_drvdata(dev); unsigned char tmp; + bool is_wkalrm_expired; if (cmos->enabled_wake) { if (cmos->wake_off) @@ -913,6 +935,8 @@ static int cmos_resume(struct device *dev) cmos->enabled_wake = 0; } + is_wkalrm_expired = cmos_is_wkalrm_expired(dev); + spin_lock_irq(&rtc_lock); tmp = cmos->suspend_ctrl; cmos->suspend_ctrl = 0; @@ -939,6 +963,17 @@ static int cmos_resume(struct device *dev) tmp &= ~RTC_AIE; hpet_mask_rtc_irq_bit(RTC_AIE); } while (mask & RTC_AIE); + + /* + * If RTC_AIE is set and we have an alarm set to go off in the + * past, then the BIOS woke the system when the alarm went off + * and we now have to clear it. + */ + if ((tmp & RTC_AIE) && is_wkalrm_expired) { + rtc_update_irq(cmos->rtc, 1, mask); + tmp &= ~RTC_AIE; + CMOS_WRITE(tmp, RTC_CONTROL); + } } spin_unlock_irq(&rtc_lock); -- 2.9.3