alarmtimer: add rtc irq support for alarm

Add the rtc irq support for alarmtimer to wakeup the
alarm during system suspend.

Change-Id: I41b774ed4e788359321e1c6a564551cc9cd40c8e
Signed-off-by: Xiaocheng Li <lix@codeaurora.org>

kernel/time/alarmtimer.c

@@ -53,6 +53,18 @@ static struct rtc_timer		rtctimer;
 static struct rtc_device	*rtcdev;
 static DEFINE_SPINLOCK(rtcdev_lock);
 
+static void alarmtimer_triggered_func(void *p)
+{
+	struct rtc_device *rtc = rtcdev;
+
+	if (!(rtc->irq_data & RTC_AF))
+		return;
+	__pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
+}
+
+static struct rtc_task alarmtimer_rtc_task = {
+	.func = alarmtimer_triggered_func
+};
 /**
  * alarmtimer_get_rtcdev - Return selected rtcdevice
  *
@@ -63,7 +75,7 @@ static DEFINE_SPINLOCK(rtcdev_lock);
 struct rtc_device *alarmtimer_get_rtcdev(void)
 {
 	unsigned long flags;
-	struct rtc_device *ret;
+	struct rtc_device *ret = NULL;
 
 	spin_lock_irqsave(&rtcdev_lock, flags);
 	ret = rtcdev;
@@ -77,24 +89,36 @@ static int alarmtimer_rtc_add_device(struct device *dev,
 				struct class_interface *class_intf)
 {
 	unsigned long flags;
+	int err = 0;
 	struct rtc_device *rtc = to_rtc_device(dev);
-
 	if (rtcdev)
 		return -EBUSY;
-
 	if (!rtc->ops->set_alarm)
 		return -1;
-	if (!device_may_wakeup(rtc->dev.parent))
-		return -1;
 
 	spin_lock_irqsave(&rtcdev_lock, flags);
 	if (!rtcdev) {
+		err = rtc_irq_register(rtc, &alarmtimer_rtc_task);
+		if (err)
+			goto rtc_irq_reg_err;
 		rtcdev = rtc;
 		/* hold a reference so it doesn't go away */
 		get_device(dev);
 	}
+
+rtc_irq_reg_err:
 	spin_unlock_irqrestore(&rtcdev_lock, flags);
-	return 0;
+	return err;
+
+}
+
+static void alarmtimer_rtc_remove_device(struct device *dev,
+				struct class_interface *class_intf)
+{
+	if (rtcdev && dev == &rtcdev->dev) {
+		rtc_irq_unregister(rtcdev, &alarmtimer_rtc_task);
+		rtcdev = NULL;
+	}
 }
 
 static inline void alarmtimer_rtc_timer_init(void)
@@ -104,6 +128,7 @@ static inline void alarmtimer_rtc_timer_init(void)
 
 static struct class_interface alarmtimer_rtc_interface = {
 	.add_dev = &alarmtimer_rtc_add_device,
+	.remove_dev = &alarmtimer_rtc_remove_device,
 };
 
 static int alarmtimer_rtc_interface_setup(void)
@@ -271,11 +296,28 @@ static int alarmtimer_suspend(struct device *dev)
 		__pm_wakeup_event(ws, MSEC_PER_SEC);
 	return ret;
 }
+
+static int alarmtimer_resume(struct device *dev)
+{
+	struct rtc_device *rtc;
+
+	rtc = alarmtimer_get_rtcdev();
+	/* If we have no rtcdev, just return */
+	if (!rtc)
+		return 0;
+	rtc_timer_cancel(rtc, &rtctimer);
+	return 0;
+}
 #else
 static int alarmtimer_suspend(struct device *dev)
 {
 	return 0;
 }
+
+static int alarmtimer_resume(struct device *dev)
+{
+	return 0;
+}
 #endif
 
 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
@@ -800,6 +842,7 @@ out:
 /* Suspend hook structures */
 static const struct dev_pm_ops alarmtimer_pm_ops = {
 	.suspend = alarmtimer_suspend,
+	.resume = alarmtimer_resume,
 };
 
 static struct platform_driver alarmtimer_driver = {