[PATCH v2 7/9] rtc: stmp3xxx: Re-enable active alarm

[Steffen Trumtrar <s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

If an alarm is set and the system rebooted, the alarm does not get re-enabled,
although it may still be valid (i.e. in the future).

The sysfs representation of wakealarms prevents overwriting active alarms. One
needs to instead write a 0 first and then the new value. Therefore an alarm is
considered active if
	wakealarm != 0 && wakealarm > now

To preserve this information over a reboot, the alarm needs to be re-written
on startup, if it is still valid. This leads to all flags being reactivated
and interrupts reenabled.

Signed-off-by: Steffen Trumtrar <s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
---
 drivers/rtc/rtc-stmp3xxx.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/rtc/rtc-stmp3xxx.c b/drivers/rtc/rtc-stmp3xxx.c
index 3ca26ac..90d0804 100644
--- a/drivers/rtc/rtc-stmp3xxx.c
+++ b/drivers/rtc/rtc-stmp3xxx.c
@@ -247,27 +247,39 @@ static int stmp3xxx_alarm_irq_enable(struct device *dev, unsigned int enabled)
 				rtc_data->io + STMP3XXX_RTC_PERSISTENT0_CLR);
 		writel(STMP3XXX_RTC_CTRL_ALARM_IRQ_EN,
 				rtc_data->io + STMP3XXX_RTC_CTRL_CLR);
+		writel(0, rtc_data->io + STMP3XXX_RTC_ALARM);
 	}
 	return 0;
 }
 
-static int stmp3xxx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
+static int stmp3xxx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
 {
+	unsigned long t;
 	struct stmp3xxx_rtc_data *rtc_data = dev_get_drvdata(dev);
 
-	rtc_time_to_tm(readl(rtc_data->io + STMP3XXX_RTC_ALARM), &alm->time);
+	rtc_tm_to_time(&alm->time, &t);
+	writel(t, rtc_data->io + STMP3XXX_RTC_ALARM);
+
+	stmp3xxx_alarm_irq_enable(dev, alm->enabled);
+
 	return 0;
 }
 
-static int stmp3xxx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
+static int stmp3xxx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
 {
-	unsigned long t;
 	struct stmp3xxx_rtc_data *rtc_data = dev_get_drvdata(dev);
+	struct rtc_time now;
+	u32 alarm = readl(rtc_data->io + STMP3XXX_RTC_ALARM);
 
-	rtc_tm_to_time(&alm->time, &t);
-	writel(t, rtc_data->io + STMP3XXX_RTC_ALARM);
+	rtc_time_to_tm(alarm, &alm->time);
 
-	stmp3xxx_alarm_irq_enable(dev, alm->enabled);
+	stmp3xxx_rtc_gettime(dev, &now);
+	if (rtc_tm_to_ktime(now).tv64 < rtc_tm_to_ktime(alm->time).tv64) {
+		alm->enabled = 1;
+		stmp3xxx_rtc_set_alarm(dev, alm);
+	} else {
+		alm->enabled = 0;
+	}
 
 	return 0;
 }
-- 
1.8.2.rc2