diff options
| -rw-r--r-- | drivers/rtc/rtc-cmos.c | 72 |
1 files changed, 49 insertions, 23 deletions
diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c index b90a603d6b12..6f47d68d2c86 100644 --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -249,10 +249,46 @@ static int cmos_set_time(struct device *dev, struct rtc_time *t) return mc146818_set_time(t); } +struct cmos_read_alarm_callback_param { + struct cmos_rtc *cmos; + struct rtc_time *time; + unsigned char rtc_control; +}; + +static void cmos_read_alarm_callback(unsigned char __always_unused seconds, + void *param_in) +{ + struct cmos_read_alarm_callback_param *p = + (struct cmos_read_alarm_callback_param *)param_in; + struct rtc_time *time = p->time; + + time->tm_sec = CMOS_READ(RTC_SECONDS_ALARM); + time->tm_min = CMOS_READ(RTC_MINUTES_ALARM); + time->tm_hour = CMOS_READ(RTC_HOURS_ALARM); + + if (p->cmos->day_alrm) { + /* ignore upper bits on readback per ACPI spec */ + time->tm_mday = CMOS_READ(p->cmos->day_alrm) & 0x3f; + if (!time->tm_mday) + time->tm_mday = -1; + + if (p->cmos->mon_alrm) { + time->tm_mon = CMOS_READ(p->cmos->mon_alrm); + if (!time->tm_mon) + time->tm_mon = -1; + } + } + + p->rtc_control = CMOS_READ(RTC_CONTROL); +} + static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t) { struct cmos_rtc *cmos = dev_get_drvdata(dev); - unsigned char rtc_control; + struct cmos_read_alarm_callback_param p = { + .cmos = cmos, + .time = &t->time, + }; /* This not only a rtc_op, but also called directly */ if (!is_valid_irq(cmos->irq)) @@ -263,28 +299,18 @@ static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t) * the future. */ - spin_lock_irq(&rtc_lock); - t->time.tm_sec = CMOS_READ(RTC_SECONDS_ALARM); - t->time.tm_min = CMOS_READ(RTC_MINUTES_ALARM); - t->time.tm_hour = CMOS_READ(RTC_HOURS_ALARM); - - if (cmos->day_alrm) { - /* ignore upper bits on readback per ACPI spec */ - t->time.tm_mday = CMOS_READ(cmos->day_alrm) & 0x3f; - if (!t->time.tm_mday) - t->time.tm_mday = -1; - - if (cmos->mon_alrm) { - t->time.tm_mon = CMOS_READ(cmos->mon_alrm); - if (!t->time.tm_mon) - t->time.tm_mon = -1; - } - } - - rtc_control = CMOS_READ(RTC_CONTROL); - spin_unlock_irq(&rtc_lock); + /* Some Intel chipsets disconnect the alarm registers when the clock + * update is in progress - during this time reads return bogus values + * and writes may fail silently. See for example "7th Generation Intel® + * Processor Family I/O for U/Y Platforms [...] Datasheet", section + * 27.7.1 + * + * Use the mc146818_avoid_UIP() function to avoid this. + */ + if (!mc146818_avoid_UIP(cmos_read_alarm_callback, &p)) + return -EIO; - if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { + if (!(p.rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { if (((unsigned)t->time.tm_sec) < 0x60) t->time.tm_sec = bcd2bin(t->time.tm_sec); else @@ -313,7 +339,7 @@ static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t) } } - t->enabled = !!(rtc_control & RTC_AIE); + t->enabled = !!(p.rtc_control & RTC_AIE); t->pending = 0; return 0; |