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 2011-01-11 09:42:13 -08:00
parent 88d19cf379
commit ff3ead96d1
3 changed files with 406 additions and 1 deletions

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#ifndef _LINUX_ALARMTIMER_H
#define _LINUX_ALARMTIMER_H
#include <linux/time.h>
#include <linux/hrtimer.h>
#include <linux/timerqueue.h>
#include <linux/rtc.h>
enum alarmtimer_type {
ALARM_REALTIME,
ALARM_BOOTTIME,
ALARM_NUMTYPE,
};
struct alarm {
struct timerqueue_node node;
ktime_t period;
void (*function)(struct alarm *);
enum alarmtimer_type type;
char enabled;
void *data;
};
void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
void (*function)(struct alarm *));
void alarm_start(struct alarm *alarm, ktime_t start, ktime_t period);
void alarm_cancel(struct alarm *alarm);
#endif

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@ -1,5 +1,5 @@
obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o timecompare.o
obj-y += timeconv.o posix-clock.o
obj-y += timeconv.o posix-clock.o alarmtimer.o
obj-$(CONFIG_GENERIC_CLOCKEVENTS_BUILD) += clockevents.o
obj-$(CONFIG_GENERIC_CLOCKEVENTS) += tick-common.o

375
kernel/time/alarmtimer.c Normal file
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/*
* 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>
static struct alarm_base {
spinlock_t lock;
struct timerqueue_head timerqueue;
struct hrtimer timer;
ktime_t (*gettime)(void);
clockid_t base_clockid;
struct work_struct irqwork;
} alarm_bases[ALARM_NUMTYPE];
static struct rtc_timer rtctimer;
static struct rtc_device *rtcdev;
static ktime_t freezer_delta;
static DEFINE_SPINLOCK(freezer_delta_lock);
/**************************************************************************
* alarmtimer management code
*/
/*
* 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 and if necessary sets
* an hrtimer to run.
*
* Must hold base->lock when calling.
*/
static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
{
timerqueue_add(&base->timerqueue, &alarm->node);
if (&alarm->node == timerqueue_getnext(&base->timerqueue)) {
hrtimer_try_to_cancel(&base->timer);
hrtimer_start(&base->timer, alarm->node.expires,
HRTIMER_MODE_ABS);
}
}
/*
* alarmtimer_remove - 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 and if necessary sets
* a new timer to run.
*
* Must hold base->lock when calling.
*/
static void alarmtimer_remove(struct alarm_base *base, struct alarm *alarm)
{
struct timerqueue_node *next = timerqueue_getnext(&base->timerqueue);
timerqueue_del(&base->timerqueue, &alarm->node);
if (next == &alarm->node) {
hrtimer_try_to_cancel(&base->timer);
next = timerqueue_getnext(&base->timerqueue);
if (!next)
return;
hrtimer_start(&base->timer, next->expires, HRTIMER_MODE_ABS);
}
}
/*
* alarmtimer_do_work - Handles alarm being fired.
* @work: pointer to workqueue being run
*
* When a timer fires, this runs through the timerqueue to see
* which alarm timers, and run those that expired. If there are
* more alarm timers queued, we set the hrtimer to fire in the
* future.
*/
void alarmtimer_do_work(struct work_struct *work)
{
struct alarm_base *base = container_of(work, struct alarm_base,
irqwork);
struct timerqueue_node *next;
unsigned long flags;
ktime_t now;
spin_lock_irqsave(&base->lock, flags);
now = base->gettime();
while ((next = timerqueue_getnext(&base->timerqueue))) {
struct alarm *alarm;
ktime_t expired = next->expires;
if (expired.tv64 >= now.tv64)
break;
alarm = container_of(next, struct alarm, node);
timerqueue_del(&base->timerqueue, &alarm->node);
alarm->enabled = 0;
/* Re-add periodic timers */
if (alarm->period.tv64) {
alarm->node.expires = ktime_add(expired, alarm->period);
timerqueue_add(&base->timerqueue, &alarm->node);
alarm->enabled = 1;
}
spin_unlock_irqrestore(&base->lock, flags);
if (alarm->function)
alarm->function(alarm);
spin_lock_irqsave(&base->lock, flags);
}
if (next) {
hrtimer_start(&base->timer, next->expires,
HRTIMER_MODE_ABS);
}
spin_unlock_irqrestore(&base->lock, flags);
}
/*
* alarmtimer_fired - Handles alarm hrtimer being fired.
* @timer: pointer to hrtimer being run
*
* When a timer fires, this schedules the do_work function to
* be run.
*/
static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
{
struct alarm_base *base = container_of(timer, struct alarm_base, timer);
schedule_work(&base->irqwork);
return HRTIMER_NORESTART;
}
/*
* 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;
int i;
spin_lock_irqsave(&freezer_delta_lock, flags);
min = freezer_delta;
freezer_delta = ktime_set(0, 0);
spin_unlock_irqrestore(&freezer_delta_lock, flags);
/* If we have no rtcdev, just return */
if (!rtcdev)
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;
/* XXX - Should we enforce a minimum sleep time? */
WARN_ON(min.tv64 < NSEC_PER_SEC);
/* Setup an rtc timer to fire that far in the future */
rtc_timer_cancel(rtcdev, &rtctimer);
rtc_read_time(rtcdev, &tm);
now = rtc_tm_to_ktime(tm);
now = ktime_add(now, min);
rtc_timer_start(rtcdev, &rtctimer, now, ktime_set(0, 0));
return 0;
}
/**************************************************************************
* alarm kernel interface code
*/
/*
* 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
*
* In-kernel interface to initializes the alarm structure.
*/
void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
void (*function)(struct alarm *))
{
timerqueue_init(&alarm->node);
alarm->period = ktime_set(0, 0);
alarm->function = function;
alarm->type = type;
alarm->enabled = 0;
}
/*
* alarm_start - Sets an alarm to fire
* @alarm: ptr to alarm to set
* @start: time to run the alarm
* @period: period at which the alarm will recur
*
* In-kernel interface set an alarm timer.
*/
void alarm_start(struct alarm *alarm, ktime_t start, ktime_t period)
{
struct alarm_base *base = &alarm_bases[alarm->type];
unsigned long flags;
spin_lock_irqsave(&base->lock, flags);
if (alarm->enabled)
alarmtimer_remove(base, alarm);
alarm->node.expires = start;
alarm->period = period;
alarmtimer_enqueue(base, alarm);
alarm->enabled = 1;
spin_unlock_irqrestore(&base->lock, flags);
}
/*
* alarm_cancel - Tries to cancel an alarm timer
* @alarm: ptr to alarm to be canceled
*
* In-kernel interface to cancel an alarm timer.
*/
void alarm_cancel(struct alarm *alarm)
{
struct alarm_base *base = &alarm_bases[alarm->type];
unsigned long flags;
spin_lock_irqsave(&base->lock, flags);
if (alarm->enabled)
alarmtimer_remove(base, alarm);
alarm->enabled = 0;
spin_unlock_irqrestore(&base->lock, flags);
}
/**************************************************************************
* alarmtimer initialization code
*/
/* 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)
{
int error = 0;
int i;
/* 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);
hrtimer_init(&alarm_bases[i].timer,
alarm_bases[i].base_clockid,
HRTIMER_MODE_ABS);
alarm_bases[i].timer.function = alarmtimer_fired;
INIT_WORK(&alarm_bases[i].irqwork, alarmtimer_do_work);
}
error = platform_driver_register(&alarmtimer_driver);
platform_device_register_simple("alarmtimer", -1, NULL, 0);
return error;
}
device_initcall(alarmtimer_init);
/**
* has_wakealarm - check rtc device has wakealarm ability
* @dev: current device
* @name_ptr: name to be returned
*
* This helper function checks to see if the rtc device can wake
* from suspend.
*/
static int __init has_wakealarm(struct device *dev, void *name_ptr)
{
struct rtc_device *candidate = to_rtc_device(dev);
if (!candidate->ops->set_alarm)
return 0;
if (!device_may_wakeup(candidate->dev.parent))
return 0;
*(const char **)name_ptr = dev_name(dev);
return 1;
}
/**
* alarmtimer_init_late - Late initializing of alarmtimer code
*
* This function locates a rtc device to use for wakealarms.
* Run as late_initcall to make sure rtc devices have been
* registered.
*/
static int __init alarmtimer_init_late(void)
{
char *str;
/* Find an rtc device and init the rtc_timer */
class_find_device(rtc_class, NULL, &str, has_wakealarm);
if (str)
rtcdev = rtc_class_open(str);
if (!rtcdev) {
printk(KERN_WARNING "No RTC device found, ALARM timers will"
" not wake from suspend");
}
rtc_timer_init(&rtctimer, NULL, NULL);
return 0;
}
late_initcall(alarmtimer_init_late);