kernel/time/alarmtimer.c - arm/linux-arm64-legacy - Git at Google

 /*
  * Alarmtimer interface
  *
  * This interface provides a timer which is similarto hrtimers,
  * but triggers a RTC alarm if the box is suspend.
  *
  * This interface is influenced by the Android RTC Alarm timer
  * interface.
  *
  * Copyright (C) 2010 IBM Corperation
  *
  * Author: John Stultz <john.stultz@linaro.org>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
 #include <linux/time.h>
 #include <linux/hrtimer.h>
 #include <linux/timerqueue.h>
 #include <linux/rtc.h>
 #include <linux/alarmtimer.h>
 #include <linux/mutex.h>
 #include <linux/platform_device.h>
 #include <linux/posix-timers.h>
 #include <linux/workqueue.h>
 #include <linux/freezer.h>

 /**
  * struct alarm_base - Alarm timer bases
  * @lock:		Lock for syncrhonized access to the base
  * @timerqueue:		Timerqueue head managing the list of events
  * @timer: 		hrtimer used to schedule events while running
  * @gettime:		Function to read the time correlating to the base
  * @base_clockid:	clockid for the base
  */
 static struct alarm_base {
 	spinlock_t		lock;
 	struct timerqueue_head	timerqueue;
 	ktime_t			(*gettime)(void);
 	clockid_t		base_clockid;
 } alarm_bases[ALARM_NUMTYPE];

 /* freezer delta & lock used to handle clock_nanosleep triggered wakeups */
 static ktime_t freezer_delta;
 static DEFINE_SPINLOCK(freezer_delta_lock);

 static struct wakeup_source *ws;

 #ifdef CONFIG_RTC_CLASS
 /* rtc timer and device for setting alarm wakeups at suspend */
 static struct rtc_timer		rtctimer;
 static struct rtc_device	*rtcdev;
 static DEFINE_SPINLOCK(rtcdev_lock);

 /**
  * alarmtimer_get_rtcdev - Return selected rtcdevice
  *
  * This function returns the rtc device to use for wakealarms.
  * If one has not already been chosen, it checks to see if a
  * functional rtc device is available.
  */
 struct rtc_device *alarmtimer_get_rtcdev(void)
 {
 	unsigned long flags;
 	struct rtc_device *ret;

 	spin_lock_irqsave(&rtcdev_lock, flags);
 	ret = rtcdev;
 	spin_unlock_irqrestore(&rtcdev_lock, flags);

 	return ret;
 }


 static int alarmtimer_rtc_add_device(struct device *dev,
 				struct class_interface *class_intf)
 {
 	unsigned long flags;
 	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) {
 		rtcdev = rtc;
 		/* hold a reference so it doesn't go away */
 		get_device(dev);
 	}
 	spin_unlock_irqrestore(&rtcdev_lock, flags);
 	return 0;
 }

 static inline void alarmtimer_rtc_timer_init(void)
 {
 	rtc_timer_init(&rtctimer, NULL, NULL);
 }

 static struct class_interface alarmtimer_rtc_interface = {
 	.add_dev = &alarmtimer_rtc_add_device,
 };

 static int alarmtimer_rtc_interface_setup(void)
 {
 	alarmtimer_rtc_interface.class = rtc_class;
 	return class_interface_register(&alarmtimer_rtc_interface);
 }
 static void alarmtimer_rtc_interface_remove(void)
 {
 	class_interface_unregister(&alarmtimer_rtc_interface);
 }
 #else
 struct rtc_device *alarmtimer_get_rtcdev(void)
 {
 	return NULL;
 }
 #define rtcdev (NULL)
 static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
 static inline void alarmtimer_rtc_interface_remove(void) { }
 static inline void alarmtimer_rtc_timer_init(void) { }
 #endif

 /**
  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
  * @base: pointer to the base where the timer is being run
  * @alarm: pointer to alarm being enqueued.
  *
  * Adds alarm to a alarm_base timerqueue
  *
  * Must hold base->lock when calling.
  */
 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
 {
 	if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
 		timerqueue_del(&base->timerqueue, &alarm->node);

 	timerqueue_add(&base->timerqueue, &alarm->node);
 	alarm->state |= ALARMTIMER_STATE_ENQUEUED;
 }

 /**
  * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
  * @base: pointer to the base where the timer is running
  * @alarm: pointer to alarm being removed
  *
  * Removes alarm to a alarm_base timerqueue
  *
  * Must hold base->lock when calling.
  */
 static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
 {
 	if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
 		return;

 	timerqueue_del(&base->timerqueue, &alarm->node);
 	alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
 }


 /**
  * alarmtimer_fired - Handles alarm hrtimer being fired.
  * @timer: pointer to hrtimer being run
  *
  * When a alarm timer fires, this runs through the timerqueue to
  * see which alarms expired, and runs those. If there are more alarm
  * timers queued for the future, we set the hrtimer to fire when
  * when the next future alarm timer expires.
  */
 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 {
 	struct alarm *alarm = container_of(timer, struct alarm, timer);
 	struct alarm_base *base = &alarm_bases[alarm->type];
 	unsigned long flags;
 	int ret = HRTIMER_NORESTART;
 	int restart = ALARMTIMER_NORESTART;

 	spin_lock_irqsave(&base->lock, flags);
 	alarmtimer_dequeue(base, alarm);
 	spin_unlock_irqrestore(&base->lock, flags);

 	if (alarm->function)
 		restart = alarm->function(alarm, base->gettime());

 	spin_lock_irqsave(&base->lock, flags);
 	if (restart != ALARMTIMER_NORESTART) {
 		hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 		alarmtimer_enqueue(base, alarm);
 		ret = HRTIMER_RESTART;
 	}
 	spin_unlock_irqrestore(&base->lock, flags);

 	return ret;

 }

 ktime_t alarm_expires_remaining(const struct alarm *alarm)
 {
 	struct alarm_base *base = &alarm_bases[alarm->type];
 	return ktime_sub(alarm->node.expires, base->gettime());
 }
 EXPORT_SYMBOL_GPL(alarm_expires_remaining);

 #ifdef CONFIG_RTC_CLASS
 /**
  * alarmtimer_suspend - Suspend time callback
  * @dev: unused
  * @state: unused
  *
  * When we are going into suspend, we look through the bases
  * to see which is the soonest timer to expire. We then
  * set an rtc timer to fire that far into the future, which
  * will wake us from suspend.
  */
 static int alarmtimer_suspend(struct device *dev)
 {
 	struct rtc_time tm;
 	ktime_t min, now;
 	unsigned long flags;
 	struct rtc_device *rtc;
 	int i;
 	int ret;

 	spin_lock_irqsave(&freezer_delta_lock, flags);
 	min = freezer_delta;
 	freezer_delta = ktime_set(0, 0);
 	spin_unlock_irqrestore(&freezer_delta_lock, flags);

 	rtc = alarmtimer_get_rtcdev();
 	/* If we have no rtcdev, just return */
 	if (!rtc)
 		return 0;

 	/* Find the soonest timer to expire*/
 	for (i = 0; i < ALARM_NUMTYPE; i++) {
 		struct alarm_base *base = &alarm_bases[i];
 		struct timerqueue_node *next;
 		ktime_t delta;

 		spin_lock_irqsave(&base->lock, flags);
 		next = timerqueue_getnext(&base->timerqueue);
 		spin_unlock_irqrestore(&base->lock, flags);
 		if (!next)
 			continue;
 		delta = ktime_sub(next->expires, base->gettime());
 		if (!min.tv64 || (delta.tv64 < min.tv64))
 			min = delta;
 	}
 	if (min.tv64 == 0)
 		return 0;

 	if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
 		__pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
 		return -EBUSY;
 	}

 	/* Setup an rtc timer to fire that far in the future */
 	rtc_timer_cancel(rtc, &rtctimer);
 	rtc_read_time(rtc, &tm);
 	now = rtc_tm_to_ktime(tm);
 	now = ktime_add(now, min);

 	/* Set alarm, if in the past reject suspend briefly to handle */
 	ret = rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0));
 	if (ret < 0)
 		__pm_wakeup_event(ws, MSEC_PER_SEC);
 	return ret;
 }
 #else
 static int alarmtimer_suspend(struct device *dev)
 {
 	return 0;
 }
 #endif

 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 {
 	ktime_t delta;
 	unsigned long flags;
 	struct alarm_base *base = &alarm_bases[type];

 	delta = ktime_sub(absexp, base->gettime());

 	spin_lock_irqsave(&freezer_delta_lock, flags);
 	if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64))
 		freezer_delta = delta;
 	spin_unlock_irqrestore(&freezer_delta_lock, flags);
 }


 /**
  * alarm_init - Initialize an alarm structure
  * @alarm: ptr to alarm to be initialized
  * @type: the type of the alarm
  * @function: callback that is run when the alarm fires
  */
 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 		enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 {
 	timerqueue_init(&alarm->node);
 	hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
 			HRTIMER_MODE_ABS);
 	alarm->timer.function = alarmtimer_fired;
 	alarm->function = function;
 	alarm->type = type;
 	alarm->state = ALARMTIMER_STATE_INACTIVE;
 }
 EXPORT_SYMBOL_GPL(alarm_init);

 /**
  * alarm_start - Sets an absolute alarm to fire
  * @alarm: ptr to alarm to set
  * @start: time to run the alarm
  */
 int alarm_start(struct alarm *alarm, ktime_t start)
 {
 	struct alarm_base *base = &alarm_bases[alarm->type];
 	unsigned long flags;
 	int ret;

 	spin_lock_irqsave(&base->lock, flags);
 	alarm->node.expires = start;
 	alarmtimer_enqueue(base, alarm);
 	ret = hrtimer_start(&alarm->timer, alarm->node.expires,
 				HRTIMER_MODE_ABS);
 	spin_unlock_irqrestore(&base->lock, flags);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(alarm_start);

 /**
  * alarm_start_relative - Sets a relative alarm to fire
  * @alarm: ptr to alarm to set
  * @start: time relative to now to run the alarm
  */
 int alarm_start_relative(struct alarm *alarm, ktime_t start)
 {
 	struct alarm_base *base = &alarm_bases[alarm->type];

 	start = ktime_add(start, base->gettime());
 	return alarm_start(alarm, start);
 }
 EXPORT_SYMBOL_GPL(alarm_start_relative);

 void alarm_restart(struct alarm *alarm)
 {
 	struct alarm_base *base = &alarm_bases[alarm->type];
 	unsigned long flags;

 	spin_lock_irqsave(&base->lock, flags);
 	hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 	hrtimer_restart(&alarm->timer);
 	alarmtimer_enqueue(base, alarm);
 	spin_unlock_irqrestore(&base->lock, flags);
 }
 EXPORT_SYMBOL_GPL(alarm_restart);

 /**
  * alarm_try_to_cancel - Tries to cancel an alarm timer
  * @alarm: ptr to alarm to be canceled
  *
  * Returns 1 if the timer was canceled, 0 if it was not running,
  * and -1 if the callback was running
  */
 int alarm_try_to_cancel(struct alarm *alarm)
 {
 	struct alarm_base *base = &alarm_bases[alarm->type];
 	unsigned long flags;
 	int ret;

 	spin_lock_irqsave(&base->lock, flags);
 	ret = hrtimer_try_to_cancel(&alarm->timer);
 	if (ret >= 0)
 		alarmtimer_dequeue(base, alarm);
 	spin_unlock_irqrestore(&base->lock, flags);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);


 /**
  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
  * @alarm: ptr to alarm to be canceled
  *
  * Returns 1 if the timer was canceled, 0 if it was not active.
  */
 int alarm_cancel(struct alarm *alarm)
 {
 	for (;;) {
 		int ret = alarm_try_to_cancel(alarm);
 		if (ret >= 0)
 			return ret;
 		cpu_relax();
 	}
 }
 EXPORT_SYMBOL_GPL(alarm_cancel);


 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
 {
 	u64 overrun = 1;
 	ktime_t delta;

 	delta = ktime_sub(now, alarm->node.expires);

 	if (delta.tv64 < 0)
 		return 0;

 	if (unlikely(delta.tv64 >= interval.tv64)) {
 		s64 incr = ktime_to_ns(interval);

 		overrun = ktime_divns(delta, incr);

 		alarm->node.expires = ktime_add_ns(alarm->node.expires,
 							incr*overrun);

 		if (alarm->node.expires.tv64 > now.tv64)
 			return overrun;
 		/*
 		 * This (and the ktime_add() below) is the
 		 * correction for exact:
 		 */
 		overrun++;
 	}

 	alarm->node.expires = ktime_add(alarm->node.expires, interval);
 	return overrun;
 }
 EXPORT_SYMBOL_GPL(alarm_forward);

 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 {
 	struct alarm_base *base = &alarm_bases[alarm->type];

 	return alarm_forward(alarm, base->gettime(), interval);
 }
 EXPORT_SYMBOL_GPL(alarm_forward_now);


 /**
  * clock2alarm - helper that converts from clockid to alarmtypes
  * @clockid: clockid.
  */
 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 {
 	if (clockid == CLOCK_REALTIME_ALARM)
 		return ALARM_REALTIME;
 	if (clockid == CLOCK_BOOTTIME_ALARM)
 		return ALARM_BOOTTIME;
 	return -1;
 }

 /**
  * alarm_handle_timer - Callback for posix timers
  * @alarm: alarm that fired
  *
  * Posix timer callback for expired alarm timers.
  */
 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 							ktime_t now)
 {
 	struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 						it.alarm.alarmtimer);
 	if (posix_timer_event(ptr, 0) != 0)
 		ptr->it_overrun++;

 	/* Re-add periodic timers */
 	if (ptr->it.alarm.interval.tv64) {
 		ptr->it_overrun += alarm_forward(alarm, now,
 						ptr->it.alarm.interval);
 		return ALARMTIMER_RESTART;
 	}
 	return ALARMTIMER_NORESTART;
 }

 /**
  * alarm_clock_getres - posix getres interface
  * @which_clock: clockid
  * @tp: timespec to fill
  *
  * Returns the granularity of underlying alarm base clock
  */
 static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
 {
 	clockid_t baseid = alarm_bases[clock2alarm(which_clock)].base_clockid;

 	if (!alarmtimer_get_rtcdev())
 		return -EINVAL;

 	return hrtimer_get_res(baseid, tp);
 }

 /**
  * alarm_clock_get - posix clock_get interface
  * @which_clock: clockid
  * @tp: timespec to fill.
  *
  * Provides the underlying alarm base time.
  */
 static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
 {
 	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];

 	if (!alarmtimer_get_rtcdev())
 		return -EINVAL;

 	*tp = ktime_to_timespec(base->gettime());
 	return 0;
 }

 /**
  * alarm_timer_create - posix timer_create interface
  * @new_timer: k_itimer pointer to manage
  *
  * Initializes the k_itimer structure.
  */
 static int alarm_timer_create(struct k_itimer *new_timer)
 {
 	enum  alarmtimer_type type;
 	struct alarm_base *base;

 	if (!alarmtimer_get_rtcdev())
 		return -ENOTSUPP;

 	if (!capable(CAP_WAKE_ALARM))
 		return -EPERM;

 	type = clock2alarm(new_timer->it_clock);
 	base = &alarm_bases[type];
 	alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 	return 0;
 }

 /**
  * alarm_timer_get - posix timer_get interface
  * @new_timer: k_itimer pointer
  * @cur_setting: itimerspec data to fill
  *
  * Copies the itimerspec data out from the k_itimer
  */
 static void alarm_timer_get(struct k_itimer *timr,
 				struct itimerspec *cur_setting)
 {
 	memset(cur_setting, 0, sizeof(struct itimerspec));

 	cur_setting->it_interval =
 			ktime_to_timespec(timr->it.alarm.interval);
 	cur_setting->it_value =
 		ktime_to_timespec(timr->it.alarm.alarmtimer.node.expires);
 	return;
 }

 /**
  * alarm_timer_del - posix timer_del interface
  * @timr: k_itimer pointer to be deleted
  *
  * Cancels any programmed alarms for the given timer.
  */
 static int alarm_timer_del(struct k_itimer *timr)
 {
 	if (!rtcdev)
 		return -ENOTSUPP;

 	if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 		return TIMER_RETRY;

 	return 0;
 }

 /**
  * alarm_timer_set - posix timer_set interface
  * @timr: k_itimer pointer to be deleted
  * @flags: timer flags
  * @new_setting: itimerspec to be used
  * @old_setting: itimerspec being replaced
  *
  * Sets the timer to new_setting, and starts the timer.
  */
 static int alarm_timer_set(struct k_itimer *timr, int flags,
 				struct itimerspec *new_setting,
 				struct itimerspec *old_setting)
 {
 	ktime_t exp;

 	if (!rtcdev)
 		return -ENOTSUPP;

 	if (flags & ~TIMER_ABSTIME)
 		return -EINVAL;

 	if (old_setting)
 		alarm_timer_get(timr, old_setting);

 	/* If the timer was already set, cancel it */
 	if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 		return TIMER_RETRY;

 	/* start the timer */
 	timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
 	exp = timespec_to_ktime(new_setting->it_value);
 	/* Convert (if necessary) to absolute time */
 	if (flags != TIMER_ABSTIME) {
 		ktime_t now;

 		now = alarm_bases[timr->it.alarm.alarmtimer.type].gettime();
 		exp = ktime_add(now, exp);
 	}

 	alarm_start(&timr->it.alarm.alarmtimer, exp);
 	return 0;
 }

 /**
  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
  * @alarm: ptr to alarm that fired
  *
  * Wakes up the task that set the alarmtimer
  */
 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 								ktime_t now)
 {
 	struct task_struct *task = (struct task_struct *)alarm->data;

 	alarm->data = NULL;
 	if (task)
 		wake_up_process(task);
 	return ALARMTIMER_NORESTART;
 }

 /**
  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
  * @alarm: ptr to alarmtimer
  * @absexp: absolute expiration time
  *
  * Sets the alarm timer and sleeps until it is fired or interrupted.
  */
 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
 {
 	alarm->data = (void *)current;
 	do {
 		set_current_state(TASK_INTERRUPTIBLE);
 		alarm_start(alarm, absexp);
 		if (likely(alarm->data))
 			schedule();

 		alarm_cancel(alarm);
 	} while (alarm->data && !signal_pending(current));

 	__set_current_state(TASK_RUNNING);

 	return (alarm->data == NULL);
 }


 /**
  * update_rmtp - Update remaining timespec value
  * @exp: expiration time
  * @type: timer type
  * @rmtp: user pointer to remaining timepsec value
  *
  * Helper function that fills in rmtp value with time between
  * now and the exp value
  */
 static int update_rmtp(ktime_t exp, enum  alarmtimer_type type,
 			struct timespec __user *rmtp)
 {
 	struct timespec rmt;
 	ktime_t rem;

 	rem = ktime_sub(exp, alarm_bases[type].gettime());

 	if (rem.tv64 <= 0)
 		return 0;
 	rmt = ktime_to_timespec(rem);

 	if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
 		return -EFAULT;

 	return 1;

 }

 /**
  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
  * @restart: ptr to restart block
  *
  * Handles restarted clock_nanosleep calls
  */
 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 {
 	enum  alarmtimer_type type = restart->nanosleep.clockid;
 	ktime_t exp;
 	struct timespec __user  *rmtp;
 	struct alarm alarm;
 	int ret = 0;

 	exp.tv64 = restart->nanosleep.expires;
 	alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);

 	if (alarmtimer_do_nsleep(&alarm, exp))
 		goto out;

 	if (freezing(current))
 		alarmtimer_freezerset(exp, type);

 	rmtp = restart->nanosleep.rmtp;
 	if (rmtp) {
 		ret = update_rmtp(exp, type, rmtp);
 		if (ret <= 0)
 			goto out;
 	}


 	/* The other values in restart are already filled in */
 	ret = -ERESTART_RESTARTBLOCK;
 out:
 	return ret;
 }

 /**
  * alarm_timer_nsleep - alarmtimer nanosleep
  * @which_clock: clockid
  * @flags: determins abstime or relative
  * @tsreq: requested sleep time (abs or rel)
  * @rmtp: remaining sleep time saved
  *
  * Handles clock_nanosleep calls against _ALARM clockids
  */
 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 		     struct timespec *tsreq, struct timespec __user *rmtp)
 {
 	enum  alarmtimer_type type = clock2alarm(which_clock);
 	struct alarm alarm;
 	ktime_t exp;
 	int ret = 0;
 	struct restart_block *restart;

 	if (!alarmtimer_get_rtcdev())
 		return -ENOTSUPP;

 	if (flags & ~TIMER_ABSTIME)
 		return -EINVAL;

 	if (!capable(CAP_WAKE_ALARM))
 		return -EPERM;

 	alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);

 	exp = timespec_to_ktime(*tsreq);
 	/* Convert (if necessary) to absolute time */
 	if (flags != TIMER_ABSTIME) {
 		ktime_t now = alarm_bases[type].gettime();
 		exp = ktime_add(now, exp);
 	}

 	if (alarmtimer_do_nsleep(&alarm, exp))
 		goto out;

 	if (freezing(current))
 		alarmtimer_freezerset(exp, type);

 	/* abs timers don't set remaining time or restart */
 	if (flags == TIMER_ABSTIME) {
 		ret = -ERESTARTNOHAND;
 		goto out;
 	}

 	if (rmtp) {
 		ret = update_rmtp(exp, type, rmtp);
 		if (ret <= 0)
 			goto out;
 	}

 	restart = &current_thread_info()->restart_block;
 	restart->fn = alarm_timer_nsleep_restart;
 	restart->nanosleep.clockid = type;
 	restart->nanosleep.expires = exp.tv64;
 	restart->nanosleep.rmtp = rmtp;
 	ret = -ERESTART_RESTARTBLOCK;

 out:
 	return ret;
 }


 /* Suspend hook structures */
 static const struct dev_pm_ops alarmtimer_pm_ops = {
 	.suspend = alarmtimer_suspend,
 };

 static struct platform_driver alarmtimer_driver = {
 	.driver = {
 		.name = "alarmtimer",
 		.pm = &alarmtimer_pm_ops,
 	}
 };

 /**
  * alarmtimer_init - Initialize alarm timer code
  *
  * This function initializes the alarm bases and registers
  * the posix clock ids.
  */
 static int __init alarmtimer_init(void)
 {
 	struct platform_device *pdev;
 	int error = 0;
 	int i;
 	struct k_clock alarm_clock = {
 		.clock_getres	= alarm_clock_getres,
 		.clock_get	= alarm_clock_get,
 		.timer_create	= alarm_timer_create,
 		.timer_set	= alarm_timer_set,
 		.timer_del	= alarm_timer_del,
 		.timer_get	= alarm_timer_get,
 		.nsleep		= alarm_timer_nsleep,
 	};

 	alarmtimer_rtc_timer_init();

 	posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
 	posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);

 	/* Initialize alarm bases */
 	alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 	alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
 	alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 	alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
 	for (i = 0; i < ALARM_NUMTYPE; i++) {
 		timerqueue_init_head(&alarm_bases[i].timerqueue);
 		spin_lock_init(&alarm_bases[i].lock);
 	}

 	error = alarmtimer_rtc_interface_setup();
 	if (error)
 		return error;

 	error = platform_driver_register(&alarmtimer_driver);
 	if (error)
 		goto out_if;

 	pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
 	if (IS_ERR(pdev)) {
 		error = PTR_ERR(pdev);
 		goto out_drv;
 	}
 	ws = wakeup_source_register("alarmtimer");
 	return 0;

 out_drv:
 	platform_driver_unregister(&alarmtimer_driver);
 out_if:
 	alarmtimer_rtc_interface_remove();
 	return error;
 }
 device_initcall(alarmtimer_init);
	/*
	* Alarmtimer interface
	*
	* This interface provides a timer which is similarto hrtimers,
	* but triggers a RTC alarm if the box is suspend.
	*
	* This interface is influenced by the Android RTC Alarm timer
	* interface.
	*
	* Copyright (C) 2010 IBM Corperation
	*
	* Author: John Stultz <john.stultz@linaro.org>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/
	#include <linux/time.h>
	#include <linux/hrtimer.h>
	#include <linux/timerqueue.h>
	#include <linux/rtc.h>
	#include <linux/alarmtimer.h>
	#include <linux/mutex.h>
	#include <linux/platform_device.h>
	#include <linux/posix-timers.h>
	#include <linux/workqueue.h>
	#include <linux/freezer.h>

	/**
	* struct alarm_base - Alarm timer bases
	* @lock: Lock for syncrhonized access to the base
	* @timerqueue: Timerqueue head managing the list of events
	* @timer: hrtimer used to schedule events while running
	* @gettime: Function to read the time correlating to the base
	* @base_clockid: clockid for the base
	*/
	static struct alarm_base {
	spinlock_t lock;
	struct timerqueue_head timerqueue;
	ktime_t (*gettime)(void);
	clockid_t base_clockid;
	} alarm_bases[ALARM_NUMTYPE];

	/* freezer delta & lock used to handle clock_nanosleep triggered wakeups */
	static ktime_t freezer_delta;
	static DEFINE_SPINLOCK(freezer_delta_lock);

	static struct wakeup_source *ws;

	#ifdef CONFIG_RTC_CLASS
	/* rtc timer and device for setting alarm wakeups at suspend */
	static struct rtc_timer rtctimer;
	static struct rtc_device *rtcdev;
	static DEFINE_SPINLOCK(rtcdev_lock);

	/**
	* alarmtimer_get_rtcdev - Return selected rtcdevice
	*
	* This function returns the rtc device to use for wakealarms.
	* If one has not already been chosen, it checks to see if a
	* functional rtc device is available.
	*/
	struct rtc_device *alarmtimer_get_rtcdev(void)
	{
	unsigned long flags;
	struct rtc_device *ret;

	spin_lock_irqsave(&rtcdev_lock, flags);
	ret = rtcdev;
	spin_unlock_irqrestore(&rtcdev_lock, flags);

	return ret;
	}


	static int alarmtimer_rtc_add_device(struct device *dev,
	struct class_interface *class_intf)
	{
	unsigned long flags;
	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) {
	rtcdev = rtc;
	/* hold a reference so it doesn't go away */
	get_device(dev);
	}
	spin_unlock_irqrestore(&rtcdev_lock, flags);
	return 0;
	}

	static inline void alarmtimer_rtc_timer_init(void)
	{
	rtc_timer_init(&rtctimer, NULL, NULL);
	}

	static struct class_interface alarmtimer_rtc_interface = {
	.add_dev = &alarmtimer_rtc_add_device,
	};

	static int alarmtimer_rtc_interface_setup(void)
	{
	alarmtimer_rtc_interface.class = rtc_class;
	return class_interface_register(&alarmtimer_rtc_interface);
	}
	static void alarmtimer_rtc_interface_remove(void)
	{
	class_interface_unregister(&alarmtimer_rtc_interface);
	}
	#else
	struct rtc_device *alarmtimer_get_rtcdev(void)
	{
	return NULL;
	}
	#define rtcdev (NULL)
	static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
	static inline void alarmtimer_rtc_interface_remove(void) { }
	static inline void alarmtimer_rtc_timer_init(void) { }
	#endif

	/**
	* alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
	* @base: pointer to the base where the timer is being run
	* @alarm: pointer to alarm being enqueued.
	*
	* Adds alarm to a alarm_base timerqueue
	*
	* Must hold base->lock when calling.
	*/
	static void alarmtimer_enqueue(struct alarm_base base, struct alarm alarm)
	{
	if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
	timerqueue_del(&base->timerqueue, &alarm->node);

	timerqueue_add(&base->timerqueue, &alarm->node);
	alarm->state \|= ALARMTIMER_STATE_ENQUEUED;
	}

	/**
	* alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
	* @base: pointer to the base where the timer is running
	* @alarm: pointer to alarm being removed
	*
	* Removes alarm to a alarm_base timerqueue
	*
	* Must hold base->lock when calling.
	*/
	static void alarmtimer_dequeue(struct alarm_base base, struct alarm alarm)
	{
	if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
	return;

	timerqueue_del(&base->timerqueue, &alarm->node);
	alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
	}


	/**
	* alarmtimer_fired - Handles alarm hrtimer being fired.
	* @timer: pointer to hrtimer being run
	*
	* When a alarm timer fires, this runs through the timerqueue to
	* see which alarms expired, and runs those. If there are more alarm
	* timers queued for the future, we set the hrtimer to fire when
	* when the next future alarm timer expires.
	*/
	static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
	{
	struct alarm *alarm = container_of(timer, struct alarm, timer);
	struct alarm_base *base = &alarm_bases[alarm->type];
	unsigned long flags;
	int ret = HRTIMER_NORESTART;
	int restart = ALARMTIMER_NORESTART;

	spin_lock_irqsave(&base->lock, flags);
	alarmtimer_dequeue(base, alarm);
	spin_unlock_irqrestore(&base->lock, flags);

	if (alarm->function)
	restart = alarm->function(alarm, base->gettime());

	spin_lock_irqsave(&base->lock, flags);
	if (restart != ALARMTIMER_NORESTART) {
	hrtimer_set_expires(&alarm->timer, alarm->node.expires);
	alarmtimer_enqueue(base, alarm);
	ret = HRTIMER_RESTART;
	}
	spin_unlock_irqrestore(&base->lock, flags);

	return ret;

	}

	ktime_t alarm_expires_remaining(const struct alarm *alarm)
	{
	struct alarm_base *base = &alarm_bases[alarm->type];
	return ktime_sub(alarm->node.expires, base->gettime());
	}
	EXPORT_SYMBOL_GPL(alarm_expires_remaining);

	#ifdef CONFIG_RTC_CLASS
	/**
	* alarmtimer_suspend - Suspend time callback
	* @dev: unused
	* @state: unused
	*
	* When we are going into suspend, we look through the bases
	* to see which is the soonest timer to expire. We then
	* set an rtc timer to fire that far into the future, which
	* will wake us from suspend.
	*/
	static int alarmtimer_suspend(struct device *dev)
	{
	struct rtc_time tm;
	ktime_t min, now;
	unsigned long flags;
	struct rtc_device *rtc;
	int i;
	int ret;

	spin_lock_irqsave(&freezer_delta_lock, flags);
	min = freezer_delta;
	freezer_delta = ktime_set(0, 0);
	spin_unlock_irqrestore(&freezer_delta_lock, flags);

	rtc = alarmtimer_get_rtcdev();
	/* If we have no rtcdev, just return */
	if (!rtc)
	return 0;

	/* Find the soonest timer to expire*/
	for (i = 0; i < ALARM_NUMTYPE; i++) {
	struct alarm_base *base = &alarm_bases[i];
	struct timerqueue_node *next;
	ktime_t delta;

	spin_lock_irqsave(&base->lock, flags);
	next = timerqueue_getnext(&base->timerqueue);
	spin_unlock_irqrestore(&base->lock, flags);
	if (!next)
	continue;
	delta = ktime_sub(next->expires, base->gettime());
	if (!min.tv64 \|\| (delta.tv64 < min.tv64))
	min = delta;
	}
	if (min.tv64 == 0)
	return 0;

	if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
	__pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
	return -EBUSY;
	}

	/* Setup an rtc timer to fire that far in the future */
	rtc_timer_cancel(rtc, &rtctimer);
	rtc_read_time(rtc, &tm);
	now = rtc_tm_to_ktime(tm);
	now = ktime_add(now, min);

	/* Set alarm, if in the past reject suspend briefly to handle */
	ret = rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0));
	if (ret < 0)
	__pm_wakeup_event(ws, MSEC_PER_SEC);
	return ret;
	}
	#else
	static int alarmtimer_suspend(struct device *dev)
	{
	return 0;
	}
	#endif

	static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
	{
	ktime_t delta;
	unsigned long flags;
	struct alarm_base *base = &alarm_bases[type];

	delta = ktime_sub(absexp, base->gettime());

	spin_lock_irqsave(&freezer_delta_lock, flags);
	if (!freezer_delta.tv64 \|\| (delta.tv64 < freezer_delta.tv64))
	freezer_delta = delta;
	spin_unlock_irqrestore(&freezer_delta_lock, flags);
	}


	/**
	* alarm_init - Initialize an alarm structure
	* @alarm: ptr to alarm to be initialized
	* @type: the type of the alarm
	* @function: callback that is run when the alarm fires
	*/
	void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
	enum alarmtimer_restart (function)(struct alarm , ktime_t))
	{
	timerqueue_init(&alarm->node);
	hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
	HRTIMER_MODE_ABS);
	alarm->timer.function = alarmtimer_fired;
	alarm->function = function;
	alarm->type = type;
	alarm->state = ALARMTIMER_STATE_INACTIVE;
	}
	EXPORT_SYMBOL_GPL(alarm_init);

	/**
	* alarm_start - Sets an absolute alarm to fire
	* @alarm: ptr to alarm to set
	* @start: time to run the alarm
	*/
	int alarm_start(struct alarm *alarm, ktime_t start)
	{
	struct alarm_base *base = &alarm_bases[alarm->type];
	unsigned long flags;
	int ret;

	spin_lock_irqsave(&base->lock, flags);
	alarm->node.expires = start;
	alarmtimer_enqueue(base, alarm);
	ret = hrtimer_start(&alarm->timer, alarm->node.expires,
	HRTIMER_MODE_ABS);
	spin_unlock_irqrestore(&base->lock, flags);
	return ret;
	}
	EXPORT_SYMBOL_GPL(alarm_start);

	/**
	* alarm_start_relative - Sets a relative alarm to fire
	* @alarm: ptr to alarm to set
	* @start: time relative to now to run the alarm
	*/
	int alarm_start_relative(struct alarm *alarm, ktime_t start)
	{
	struct alarm_base *base = &alarm_bases[alarm->type];

	start = ktime_add(start, base->gettime());
	return alarm_start(alarm, start);
	}
	EXPORT_SYMBOL_GPL(alarm_start_relative);

	void alarm_restart(struct alarm *alarm)
	{
	struct alarm_base *base = &alarm_bases[alarm->type];
	unsigned long flags;

	spin_lock_irqsave(&base->lock, flags);
	hrtimer_set_expires(&alarm->timer, alarm->node.expires);
	hrtimer_restart(&alarm->timer);
	alarmtimer_enqueue(base, alarm);
	spin_unlock_irqrestore(&base->lock, flags);
	}
	EXPORT_SYMBOL_GPL(alarm_restart);

	/**
	* alarm_try_to_cancel - Tries to cancel an alarm timer
	* @alarm: ptr to alarm to be canceled
	*
	* Returns 1 if the timer was canceled, 0 if it was not running,
	* and -1 if the callback was running
	*/
	int alarm_try_to_cancel(struct alarm *alarm)
	{
	struct alarm_base *base = &alarm_bases[alarm->type];
	unsigned long flags;
	int ret;

	spin_lock_irqsave(&base->lock, flags);
	ret = hrtimer_try_to_cancel(&alarm->timer);
	if (ret >= 0)
	alarmtimer_dequeue(base, alarm);
	spin_unlock_irqrestore(&base->lock, flags);
	return ret;
	}
	EXPORT_SYMBOL_GPL(alarm_try_to_cancel);


	/**
	* alarm_cancel - Spins trying to cancel an alarm timer until it is done
	* @alarm: ptr to alarm to be canceled
	*
	* Returns 1 if the timer was canceled, 0 if it was not active.
	*/
	int alarm_cancel(struct alarm *alarm)
	{
	for (;;) {
	int ret = alarm_try_to_cancel(alarm);
	if (ret >= 0)
	return ret;
	cpu_relax();
	}
	}
	EXPORT_SYMBOL_GPL(alarm_cancel);


	u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
	{
	u64 overrun = 1;
	ktime_t delta;

	delta = ktime_sub(now, alarm->node.expires);

	if (delta.tv64 < 0)
	return 0;

	if (unlikely(delta.tv64 >= interval.tv64)) {
	s64 incr = ktime_to_ns(interval);

	overrun = ktime_divns(delta, incr);

	alarm->node.expires = ktime_add_ns(alarm->node.expires,
	incr*overrun);

	if (alarm->node.expires.tv64 > now.tv64)
	return overrun;
	/*
	* This (and the ktime_add() below) is the
	* correction for exact:
	*/
	overrun++;
	}

	alarm->node.expires = ktime_add(alarm->node.expires, interval);
	return overrun;
	}
	EXPORT_SYMBOL_GPL(alarm_forward);

	u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
	{
	struct alarm_base *base = &alarm_bases[alarm->type];

	return alarm_forward(alarm, base->gettime(), interval);
	}
	EXPORT_SYMBOL_GPL(alarm_forward_now);


	/**
	* clock2alarm - helper that converts from clockid to alarmtypes
	* @clockid: clockid.
	*/
	static enum alarmtimer_type clock2alarm(clockid_t clockid)
	{
	if (clockid == CLOCK_REALTIME_ALARM)
	return ALARM_REALTIME;
	if (clockid == CLOCK_BOOTTIME_ALARM)
	return ALARM_BOOTTIME;
	return -1;
	}

	/**
	* alarm_handle_timer - Callback for posix timers
	* @alarm: alarm that fired
	*
	* Posix timer callback for expired alarm timers.
	*/
	static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
	ktime_t now)
	{
	struct k_itimer *ptr = container_of(alarm, struct k_itimer,
	it.alarm.alarmtimer);
	if (posix_timer_event(ptr, 0) != 0)
	ptr->it_overrun++;

	/* Re-add periodic timers */
	if (ptr->it.alarm.interval.tv64) {
	ptr->it_overrun += alarm_forward(alarm, now,
	ptr->it.alarm.interval);
	return ALARMTIMER_RESTART;
	}
	return ALARMTIMER_NORESTART;
	}

	/**
	* alarm_clock_getres - posix getres interface
	* @which_clock: clockid
	* @tp: timespec to fill
	*
	* Returns the granularity of underlying alarm base clock
	*/
	static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
	{
	clockid_t baseid = alarm_bases[clock2alarm(which_clock)].base_clockid;

	if (!alarmtimer_get_rtcdev())
	return -EINVAL;

	return hrtimer_get_res(baseid, tp);
	}

	/**
	* alarm_clock_get - posix clock_get interface
	* @which_clock: clockid
	* @tp: timespec to fill.
	*
	* Provides the underlying alarm base time.
	*/
	static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
	{
	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];

	if (!alarmtimer_get_rtcdev())
	return -EINVAL;

	*tp = ktime_to_timespec(base->gettime());
	return 0;
	}

	/**
	* alarm_timer_create - posix timer_create interface
	* @new_timer: k_itimer pointer to manage
	*
	* Initializes the k_itimer structure.
	*/
	static int alarm_timer_create(struct k_itimer *new_timer)
	{
	enum alarmtimer_type type;
	struct alarm_base *base;

	if (!alarmtimer_get_rtcdev())
	return -ENOTSUPP;

	if (!capable(CAP_WAKE_ALARM))
	return -EPERM;

	type = clock2alarm(new_timer->it_clock);
	base = &alarm_bases[type];
	alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
	return 0;
	}

	/**
	* alarm_timer_get - posix timer_get interface
	* @new_timer: k_itimer pointer
	* @cur_setting: itimerspec data to fill
	*
	* Copies the itimerspec data out from the k_itimer
	*/
	static void alarm_timer_get(struct k_itimer *timr,
	struct itimerspec *cur_setting)
	{
	memset(cur_setting, 0, sizeof(struct itimerspec));

	cur_setting->it_interval =
	ktime_to_timespec(timr->it.alarm.interval);
	cur_setting->it_value =
	ktime_to_timespec(timr->it.alarm.alarmtimer.node.expires);
	return;
	}

	/**
	* alarm_timer_del - posix timer_del interface
	* @timr: k_itimer pointer to be deleted
	*
	* Cancels any programmed alarms for the given timer.
	*/
	static int alarm_timer_del(struct k_itimer *timr)
	{
	if (!rtcdev)
	return -ENOTSUPP;

	if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
	return TIMER_RETRY;

	return 0;
	}

	/**
	* alarm_timer_set - posix timer_set interface
	* @timr: k_itimer pointer to be deleted
	* @flags: timer flags
	* @new_setting: itimerspec to be used
	* @old_setting: itimerspec being replaced
	*
	* Sets the timer to new_setting, and starts the timer.
	*/
	static int alarm_timer_set(struct k_itimer *timr, int flags,
	struct itimerspec *new_setting,
	struct itimerspec *old_setting)
	{
	ktime_t exp;

	if (!rtcdev)
	return -ENOTSUPP;

	if (flags & ~TIMER_ABSTIME)
	return -EINVAL;

	if (old_setting)
	alarm_timer_get(timr, old_setting);

	/* If the timer was already set, cancel it */
	if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
	return TIMER_RETRY;

	/* start the timer */
	timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
	exp = timespec_to_ktime(new_setting->it_value);
	/* Convert (if necessary) to absolute time */
	if (flags != TIMER_ABSTIME) {
	ktime_t now;

	now = alarm_bases[timr->it.alarm.alarmtimer.type].gettime();
	exp = ktime_add(now, exp);
	}

	alarm_start(&timr->it.alarm.alarmtimer, exp);
	return 0;
	}

	/**
	* alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
	* @alarm: ptr to alarm that fired
	*
	* Wakes up the task that set the alarmtimer
	*/
	static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
	ktime_t now)
	{
	struct task_struct task = (struct task_struct )alarm->data;

	alarm->data = NULL;
	if (task)
	wake_up_process(task);
	return ALARMTIMER_NORESTART;
	}

	/**
	* alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
	* @alarm: ptr to alarmtimer
	* @absexp: absolute expiration time
	*
	* Sets the alarm timer and sleeps until it is fired or interrupted.
	*/
	static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
	{
	alarm->data = (void *)current;
	do {
	set_current_state(TASK_INTERRUPTIBLE);
	alarm_start(alarm, absexp);
	if (likely(alarm->data))
	schedule();

	alarm_cancel(alarm);
	} while (alarm->data && !signal_pending(current));

	__set_current_state(TASK_RUNNING);

	return (alarm->data == NULL);
	}


	/**
	* update_rmtp - Update remaining timespec value
	* @exp: expiration time
	* @type: timer type
	* @rmtp: user pointer to remaining timepsec value
	*
	* Helper function that fills in rmtp value with time between
	* now and the exp value
	*/
	static int update_rmtp(ktime_t exp, enum alarmtimer_type type,
	struct timespec __user *rmtp)
	{
	struct timespec rmt;
	ktime_t rem;

	rem = ktime_sub(exp, alarm_bases[type].gettime());

	if (rem.tv64 <= 0)
	return 0;
	rmt = ktime_to_timespec(rem);

	if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
	return -EFAULT;

	return 1;

	}

	/**
	* alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
	* @restart: ptr to restart block
	*
	* Handles restarted clock_nanosleep calls
	*/
	static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
	{
	enum alarmtimer_type type = restart->nanosleep.clockid;
	ktime_t exp;
	struct timespec __user *rmtp;
	struct alarm alarm;
	int ret = 0;

	exp.tv64 = restart->nanosleep.expires;
	alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);

	if (alarmtimer_do_nsleep(&alarm, exp))
	goto out;

	if (freezing(current))
	alarmtimer_freezerset(exp, type);

	rmtp = restart->nanosleep.rmtp;
	if (rmtp) {
	ret = update_rmtp(exp, type, rmtp);
	if (ret <= 0)
	goto out;
	}


	/* The other values in restart are already filled in */
	ret = -ERESTART_RESTARTBLOCK;
	out:
	return ret;
	}

	/**
	* alarm_timer_nsleep - alarmtimer nanosleep
	* @which_clock: clockid
	* @flags: determins abstime or relative
	* @tsreq: requested sleep time (abs or rel)
	* @rmtp: remaining sleep time saved
	*
	* Handles clock_nanosleep calls against _ALARM clockids
	*/
	static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
	struct timespec tsreq, struct timespec __user rmtp)
	{
	enum alarmtimer_type type = clock2alarm(which_clock);
	struct alarm alarm;
	ktime_t exp;
	int ret = 0;
	struct restart_block *restart;

	if (!alarmtimer_get_rtcdev())
	return -ENOTSUPP;

	if (flags & ~TIMER_ABSTIME)
	return -EINVAL;

	if (!capable(CAP_WAKE_ALARM))
	return -EPERM;

	alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);

	exp = timespec_to_ktime(*tsreq);
	/* Convert (if necessary) to absolute time */
	if (flags != TIMER_ABSTIME) {
	ktime_t now = alarm_bases[type].gettime();
	exp = ktime_add(now, exp);
	}

	if (alarmtimer_do_nsleep(&alarm, exp))
	goto out;

	if (freezing(current))
	alarmtimer_freezerset(exp, type);

	/* abs timers don't set remaining time or restart */
	if (flags == TIMER_ABSTIME) {
	ret = -ERESTARTNOHAND;
	goto out;
	}

	if (rmtp) {
	ret = update_rmtp(exp, type, rmtp);
	if (ret <= 0)
	goto out;
	}

	restart = &current_thread_info()->restart_block;
	restart->fn = alarm_timer_nsleep_restart;
	restart->nanosleep.clockid = type;
	restart->nanosleep.expires = exp.tv64;
	restart->nanosleep.rmtp = rmtp;
	ret = -ERESTART_RESTARTBLOCK;

	out:
	return ret;
	}


	/* Suspend hook structures */
	static const struct dev_pm_ops alarmtimer_pm_ops = {
	.suspend = alarmtimer_suspend,
	};

	static struct platform_driver alarmtimer_driver = {
	.driver = {
	.name = "alarmtimer",
	.pm = &alarmtimer_pm_ops,
	}
	};

	/**
	* alarmtimer_init - Initialize alarm timer code
	*
	* This function initializes the alarm bases and registers
	* the posix clock ids.
	*/
	static int __init alarmtimer_init(void)
	{
	struct platform_device *pdev;
	int error = 0;
	int i;
	struct k_clock alarm_clock = {
	.clock_getres = alarm_clock_getres,
	.clock_get = alarm_clock_get,
	.timer_create = alarm_timer_create,
	.timer_set = alarm_timer_set,
	.timer_del = alarm_timer_del,
	.timer_get = alarm_timer_get,
	.nsleep = alarm_timer_nsleep,
	};

	alarmtimer_rtc_timer_init();

	posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
	posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);

	/* Initialize alarm bases */
	alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
	alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
	alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
	alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
	for (i = 0; i < ALARM_NUMTYPE; i++) {
	timerqueue_init_head(&alarm_bases[i].timerqueue);
	spin_lock_init(&alarm_bases[i].lock);
	}

	error = alarmtimer_rtc_interface_setup();
	if (error)
	return error;

	error = platform_driver_register(&alarmtimer_driver);
	if (error)
	goto out_if;

	pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
	if (IS_ERR(pdev)) {
	error = PTR_ERR(pdev);
	goto out_drv;
	}
	ws = wakeup_source_register("alarmtimer");
	return 0;

	out_drv:
	platform_driver_unregister(&alarmtimer_driver);
	out_if:
	alarmtimer_rtc_interface_remove();
	return error;
	}
	device_initcall(alarmtimer_init);