timers: Introduce in-kernel alarm-timer interface
This provides the in kernel interface and infrastructure for alarm-timers. Alarm-timers are a hybrid style timer, similar to hrtimers, but when the system is suspended, the RTC device is set to fire and wake the system for when the soonest alarm-timer expires. The concept for Alarm-timers was inspired by the Android Alarm driver (by Arve Hjønnevåg) found in the Android kernel tree. See: http://android.git.kernel.org/?p=kernel/common.git;a=blob;f=drivers/rtc/alarm.c;h=1250edfbdf3302f5e4ea6194847c6ef4bb7beb1c;hb=android-2.6.36 This in-kernel interface should be fairly compatible with the Android alarm driver in-kernel interface, but has the advantage of utilizing the new RTC timerqueue code instead of doing direct RTC manipulation. CC: Arve Hjønnevåg <arve@android.com> CC: Thomas Gleixner <tglx@linutronix.de> CC: Alessandro Zummo <a.zummo@towertech.it> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
This commit is contained in:
John Stultz
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30
include/linux/alarmtimer.h
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30
include/linux/alarmtimer.h
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#ifndef _LINUX_ALARMTIMER_H
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#define _LINUX_ALARMTIMER_H
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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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enum alarmtimer_type {
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ALARM_REALTIME,
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ALARM_BOOTTIME,
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ALARM_NUMTYPE,
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};
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struct alarm {
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struct timerqueue_node node;
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ktime_t period;
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void (*function)(struct alarm *);
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enum alarmtimer_type type;
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char enabled;
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void *data;
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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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void alarm_start(struct alarm *alarm, ktime_t start, ktime_t period);
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void alarm_cancel(struct alarm *alarm);
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#endif
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@ -1,5 +1,5 @@
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obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o timecompare.o
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obj-y += timeconv.o posix-clock.o
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obj-y += timeconv.o posix-clock.o alarmtimer.o
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obj-$(CONFIG_GENERIC_CLOCKEVENTS_BUILD) += clockevents.o
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obj-$(CONFIG_GENERIC_CLOCKEVENTS) += tick-common.o
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375
kernel/time/alarmtimer.c
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375
kernel/time/alarmtimer.c
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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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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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static struct rtc_timer rtctimer;
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static struct rtc_device *rtcdev;
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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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* alarmtimer management code
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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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* 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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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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* 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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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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if (expired.tv64 >= now.tv64)
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break;
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alarm = container_of(next, struct alarm, node);
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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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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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* 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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* 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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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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/* If we have no rtcdev, just return */
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if (!rtcdev)
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return 0;
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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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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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/* XXX - Should we enforce a minimum sleep time? */
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WARN_ON(min.tv64 < NSEC_PER_SEC);
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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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rtc_timer_start(rtcdev, &rtctimer, now, ktime_set(0, 0));
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return 0;
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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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* 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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* 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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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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* 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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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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* alarmtimer initialization code
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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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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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* 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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/* 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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return error;
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}
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device_initcall(alarmtimer_init);
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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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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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*(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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* 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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/* 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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return 0;
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}
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late_initcall(alarmtimer_init_late);
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