diff options
Diffstat (limited to 'drivers/rtc')
| -rw-r--r-- | drivers/rtc/rtc-cmos.c | 14 | ||||
| -rw-r--r-- | drivers/rtc/rtc-dev.c | 9 | ||||
| -rw-r--r-- | drivers/rtc/rtc-sysfs.c | 19 |
3 files changed, 35 insertions, 7 deletions
diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c index ab455ddb16c..ff7539a4dbe 100644 --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -472,10 +472,22 @@ static struct cmos_rtc cmos_rtc; static irqreturn_t cmos_interrupt(int irq, void *p) { u8 irqstat; + u8 rtc_control; spin_lock(&rtc_lock); irqstat = CMOS_READ(RTC_INTR_FLAGS); - irqstat &= (CMOS_READ(RTC_CONTROL) & RTC_IRQMASK) | RTC_IRQF; + rtc_control = CMOS_READ(RTC_CONTROL); + irqstat &= (rtc_control & RTC_IRQMASK) | RTC_IRQF; + + /* All Linux RTC alarms should be treated as if they were oneshot. + * Similar code may be needed in system wakeup paths, in case the + * alarm woke the system. + */ + if (irqstat & RTC_AIE) { + rtc_control &= ~RTC_AIE; + CMOS_WRITE(rtc_control, RTC_CONTROL); + CMOS_READ(RTC_INTR_FLAGS); + } spin_unlock(&rtc_lock); if (is_intr(irqstat)) { diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c index 025c60a17a4..90dfa0df747 100644 --- a/drivers/rtc/rtc-dev.c +++ b/drivers/rtc/rtc-dev.c @@ -246,6 +246,15 @@ static int rtc_dev_ioctl(struct inode *inode, struct file *file, /* if the driver does not provide the ioctl interface * or if that particular ioctl was not implemented * (-ENOIOCTLCMD), we will try to emulate here. + * + * Drivers *SHOULD NOT* provide ioctl implementations + * for these requests. Instead, provide methods to + * support the following code, so that the RTC's main + * features are accessible without using ioctls. + * + * RTC and alarm times will be in UTC, by preference, + * but dual-booting with MS-Windows implies RTCs must + * use the local wall clock time. */ switch (cmd) { diff --git a/drivers/rtc/rtc-sysfs.c b/drivers/rtc/rtc-sysfs.c index 2ae0e8304d3..4d27ccc4fc0 100644 --- a/drivers/rtc/rtc-sysfs.c +++ b/drivers/rtc/rtc-sysfs.c @@ -17,6 +17,13 @@ /* device attributes */ +/* + * NOTE: RTC times displayed in sysfs use the RTC's timezone. That's + * ideally UTC. However, PCs that also boot to MS-Windows normally use + * the local time and change to match daylight savings time. That affects + * attributes including date, time, since_epoch, and wakealarm. + */ + static ssize_t rtc_sysfs_show_name(struct device *dev, struct device_attribute *attr, char *buf) @@ -113,13 +120,13 @@ rtc_sysfs_show_wakealarm(struct device *dev, struct device_attribute *attr, unsigned long alarm; struct rtc_wkalrm alm; - /* Don't show disabled alarms; but the RTC could leave the - * alarm enabled after it's already triggered. Alarms are - * conceptually one-shot, even though some common hardware - * (PCs) doesn't actually work that way. + /* Don't show disabled alarms. For uniformity, RTC alarms are + * conceptually one-shot, even though some common RTCs (on PCs) + * don't actually work that way. * - * REVISIT maybe we should require RTC implementations to - * disable the RTC alarm after it triggers, for uniformity. + * NOTE: RTC implementations where the alarm doesn't match an + * exact YYYY-MM-DD HH:MM[:SS] date *must* disable their RTC + * alarms after they trigger, to ensure one-shot semantics. */ retval = rtc_read_alarm(to_rtc_device(dev), &alm); if (retval == 0 && alm.enabled) { |