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+/*
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+ * Alarmtimer interface
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+ *
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+ * This interface provides a timer which is similarto hrtimers,
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+ * but triggers a RTC alarm if the box is suspend.
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+ *
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+ * This interface is influenced by the Android RTC Alarm timer
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+ * interface.
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+ *
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+ * Copyright (C) 2010 IBM Corperation
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+ *
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+ * Author: John Stultz <john.stultz@linaro.org>
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License version 2 as
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+ * published by the Free Software Foundation.
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+ */
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+#include <linux/time.h>
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+#include <linux/hrtimer.h>
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+#include <linux/timerqueue.h>
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+#include <linux/rtc.h>
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+#include <linux/alarmtimer.h>
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+#include <linux/mutex.h>
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+#include <linux/platform_device.h>
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+#include <linux/posix-timers.h>
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+#include <linux/workqueue.h>
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+#include <linux/freezer.h>
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+
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+
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+static struct alarm_base {
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+ spinlock_t lock;
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+ struct timerqueue_head timerqueue;
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+ struct hrtimer timer;
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+ ktime_t (*gettime)(void);
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+ clockid_t base_clockid;
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+ struct work_struct irqwork;
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+} alarm_bases[ALARM_NUMTYPE];
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+
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+static struct rtc_timer rtctimer;
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+static struct rtc_device *rtcdev;
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+
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+static ktime_t freezer_delta;
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+static DEFINE_SPINLOCK(freezer_delta_lock);
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+
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+
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+/**************************************************************************
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+ * alarmtimer management code
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+ */
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+
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+/*
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+ * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
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+ * @base: pointer to the base where the timer is being run
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+ * @alarm: pointer to alarm being enqueued.
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+ *
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+ * Adds alarm to a alarm_base timerqueue and if necessary sets
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+ * an hrtimer to run.
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+ *
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+ * Must hold base->lock when calling.
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+ */
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+static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
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+{
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+ timerqueue_add(&base->timerqueue, &alarm->node);
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+ if (&alarm->node == timerqueue_getnext(&base->timerqueue)) {
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+ hrtimer_try_to_cancel(&base->timer);
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+ hrtimer_start(&base->timer, alarm->node.expires,
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+ HRTIMER_MODE_ABS);
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+ }
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+}
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+
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+/*
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+ * alarmtimer_remove - Removes an alarm timer from an alarm_base timerqueue
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+ * @base: pointer to the base where the timer is running
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+ * @alarm: pointer to alarm being removed
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+ *
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+ * Removes alarm to a alarm_base timerqueue and if necessary sets
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+ * a new timer to run.
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+ *
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+ * Must hold base->lock when calling.
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+ */
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+static void alarmtimer_remove(struct alarm_base *base, struct alarm *alarm)
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+{
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+ struct timerqueue_node *next = timerqueue_getnext(&base->timerqueue);
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+
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+ timerqueue_del(&base->timerqueue, &alarm->node);
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+ if (next == &alarm->node) {
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+ hrtimer_try_to_cancel(&base->timer);
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+ next = timerqueue_getnext(&base->timerqueue);
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+ if (!next)
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+ return;
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+ hrtimer_start(&base->timer, next->expires, HRTIMER_MODE_ABS);
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+ }
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+}
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+
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+/*
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+ * alarmtimer_do_work - Handles alarm being fired.
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+ * @work: pointer to workqueue being run
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+ *
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+ * When a timer fires, this runs through the timerqueue to see
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+ * which alarm timers, and run those that expired. If there are
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+ * more alarm timers queued, we set the hrtimer to fire in the
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+ * future.
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+ */
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+void alarmtimer_do_work(struct work_struct *work)
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+{
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+ struct alarm_base *base = container_of(work, struct alarm_base,
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+ irqwork);
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+ struct timerqueue_node *next;
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+ unsigned long flags;
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+ ktime_t now;
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+
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+ spin_lock_irqsave(&base->lock, flags);
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+ now = base->gettime();
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+ while ((next = timerqueue_getnext(&base->timerqueue))) {
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+ struct alarm *alarm;
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+ ktime_t expired = next->expires;
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+
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+ if (expired.tv64 >= now.tv64)
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+ break;
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+
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+ alarm = container_of(next, struct alarm, node);
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+
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+ timerqueue_del(&base->timerqueue, &alarm->node);
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+ alarm->enabled = 0;
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+ /* Re-add periodic timers */
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+ if (alarm->period.tv64) {
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+ alarm->node.expires = ktime_add(expired, alarm->period);
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+ timerqueue_add(&base->timerqueue, &alarm->node);
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+ alarm->enabled = 1;
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+ }
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+ spin_unlock_irqrestore(&base->lock, flags);
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+ if (alarm->function)
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+ alarm->function(alarm);
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+ spin_lock_irqsave(&base->lock, flags);
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+ }
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+
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+ if (next) {
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+ hrtimer_start(&base->timer, next->expires,
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+ HRTIMER_MODE_ABS);
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+ }
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+ spin_unlock_irqrestore(&base->lock, flags);
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+}
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+
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+
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+/*
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+ * alarmtimer_fired - Handles alarm hrtimer being fired.
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+ * @timer: pointer to hrtimer being run
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+ *
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+ * When a timer fires, this schedules the do_work function to
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+ * be run.
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+ */
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+static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
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+{
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+ struct alarm_base *base = container_of(timer, struct alarm_base, timer);
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+ schedule_work(&base->irqwork);
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+ return HRTIMER_NORESTART;
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+}
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+
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+
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+/*
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+ * alarmtimer_suspend - Suspend time callback
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+ * @dev: unused
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+ * @state: unused
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+ *
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+ * When we are going into suspend, we look through the bases
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+ * to see which is the soonest timer to expire. We then
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+ * set an rtc timer to fire that far into the future, which
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+ * will wake us from suspend.
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+ */
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+static int alarmtimer_suspend(struct device *dev)
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+{
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+ struct rtc_time tm;
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+ ktime_t min, now;
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+ unsigned long flags;
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+ int i;
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+
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+ spin_lock_irqsave(&freezer_delta_lock, flags);
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+ min = freezer_delta;
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+ freezer_delta = ktime_set(0, 0);
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+ spin_unlock_irqrestore(&freezer_delta_lock, flags);
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+
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+ /* If we have no rtcdev, just return */
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+ if (!rtcdev)
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+ return 0;
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+
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+ /* Find the soonest timer to expire*/
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+ for (i = 0; i < ALARM_NUMTYPE; i++) {
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+ struct alarm_base *base = &alarm_bases[i];
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+ struct timerqueue_node *next;
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+ ktime_t delta;
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+
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+ spin_lock_irqsave(&base->lock, flags);
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+ next = timerqueue_getnext(&base->timerqueue);
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+ spin_unlock_irqrestore(&base->lock, flags);
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+ if (!next)
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+ continue;
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+ delta = ktime_sub(next->expires, base->gettime());
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+ if (!min.tv64 || (delta.tv64 < min.tv64))
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+ min = delta;
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+ }
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+ if (min.tv64 == 0)
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+ return 0;
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+
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+ /* XXX - Should we enforce a minimum sleep time? */
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+ WARN_ON(min.tv64 < NSEC_PER_SEC);
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+
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+ /* Setup an rtc timer to fire that far in the future */
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+ rtc_timer_cancel(rtcdev, &rtctimer);
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+ rtc_read_time(rtcdev, &tm);
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+ now = rtc_tm_to_ktime(tm);
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+ now = ktime_add(now, min);
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+
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+ rtc_timer_start(rtcdev, &rtctimer, now, ktime_set(0, 0));
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+
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+ return 0;
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+}
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+
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+
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+/**************************************************************************
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+ * alarm kernel interface code
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+ */
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+
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+/*
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+ * alarm_init - Initialize an alarm structure
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+ * @alarm: ptr to alarm to be initialized
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+ * @type: the type of the alarm
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+ * @function: callback that is run when the alarm fires
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+ *
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+ * In-kernel interface to initializes the alarm structure.
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+ */
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+void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
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+ void (*function)(struct alarm *))
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+{
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+ timerqueue_init(&alarm->node);
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+ alarm->period = ktime_set(0, 0);
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+ alarm->function = function;
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+ alarm->type = type;
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+ alarm->enabled = 0;
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+}
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+
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+/*
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+ * alarm_start - Sets an alarm to fire
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+ * @alarm: ptr to alarm to set
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+ * @start: time to run the alarm
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+ * @period: period at which the alarm will recur
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+ *
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+ * In-kernel interface set an alarm timer.
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+ */
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+void alarm_start(struct alarm *alarm, ktime_t start, ktime_t period)
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+{
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+ struct alarm_base *base = &alarm_bases[alarm->type];
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+ unsigned long flags;
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+
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+ spin_lock_irqsave(&base->lock, flags);
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+ if (alarm->enabled)
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+ alarmtimer_remove(base, alarm);
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+ alarm->node.expires = start;
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+ alarm->period = period;
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+ alarmtimer_enqueue(base, alarm);
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+ alarm->enabled = 1;
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+ spin_unlock_irqrestore(&base->lock, flags);
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+}
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+
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+/*
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+ * alarm_cancel - Tries to cancel an alarm timer
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+ * @alarm: ptr to alarm to be canceled
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+ *
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+ * In-kernel interface to cancel an alarm timer.
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+ */
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+void alarm_cancel(struct alarm *alarm)
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+{
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+ struct alarm_base *base = &alarm_bases[alarm->type];
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+ unsigned long flags;
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+
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+ spin_lock_irqsave(&base->lock, flags);
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+ if (alarm->enabled)
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+ alarmtimer_remove(base, alarm);
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+ alarm->enabled = 0;
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+ spin_unlock_irqrestore(&base->lock, flags);
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+}
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+
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+
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+
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+/**************************************************************************
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+ * alarmtimer initialization code
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+ */
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+
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+/* Suspend hook structures */
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+static const struct dev_pm_ops alarmtimer_pm_ops = {
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+ .suspend = alarmtimer_suspend,
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+};
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+
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+static struct platform_driver alarmtimer_driver = {
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+ .driver = {
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+ .name = "alarmtimer",
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+ .pm = &alarmtimer_pm_ops,
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+ }
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+};
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+
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+/**
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+ * alarmtimer_init - Initialize alarm timer code
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+ *
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+ * This function initializes the alarm bases and registers
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+ * the posix clock ids.
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+ */
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+static int __init alarmtimer_init(void)
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+{
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+ int error = 0;
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+ int i;
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+
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+ /* Initialize alarm bases */
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+ alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
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+ alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
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+ alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
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+ alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
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+ for (i = 0; i < ALARM_NUMTYPE; i++) {
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+ timerqueue_init_head(&alarm_bases[i].timerqueue);
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+ spin_lock_init(&alarm_bases[i].lock);
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+ hrtimer_init(&alarm_bases[i].timer,
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+ alarm_bases[i].base_clockid,
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+ HRTIMER_MODE_ABS);
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+ alarm_bases[i].timer.function = alarmtimer_fired;
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+ INIT_WORK(&alarm_bases[i].irqwork, alarmtimer_do_work);
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+ }
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+ error = platform_driver_register(&alarmtimer_driver);
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+ platform_device_register_simple("alarmtimer", -1, NULL, 0);
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+
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+ return error;
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+}
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+device_initcall(alarmtimer_init);
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+
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+/**
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+ * has_wakealarm - check rtc device has wakealarm ability
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+ * @dev: current device
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+ * @name_ptr: name to be returned
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+ *
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+ * This helper function checks to see if the rtc device can wake
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+ * from suspend.
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+ */
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+static int __init has_wakealarm(struct device *dev, void *name_ptr)
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+{
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+ struct rtc_device *candidate = to_rtc_device(dev);
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+
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+ if (!candidate->ops->set_alarm)
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+ return 0;
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+ if (!device_may_wakeup(candidate->dev.parent))
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+ return 0;
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+
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+ *(const char **)name_ptr = dev_name(dev);
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+ return 1;
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+}
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+
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+/**
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+ * alarmtimer_init_late - Late initializing of alarmtimer code
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+ *
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+ * This function locates a rtc device to use for wakealarms.
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+ * Run as late_initcall to make sure rtc devices have been
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+ * registered.
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+ */
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+static int __init alarmtimer_init_late(void)
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+{
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+ char *str;
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+
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+ /* Find an rtc device and init the rtc_timer */
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+ class_find_device(rtc_class, NULL, &str, has_wakealarm);
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+ if (str)
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+ rtcdev = rtc_class_open(str);
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+ if (!rtcdev) {
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+ printk(KERN_WARNING "No RTC device found, ALARM timers will"
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+ " not wake from suspend");
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+ }
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+ rtc_timer_init(&rtctimer, NULL, NULL);
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+
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+ return 0;
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+}
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+late_initcall(alarmtimer_init_late);
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