- 根目录:
- kernel
- time
- alarmtimer.c
/*
* 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;
struct hrtimer timer;
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);
#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);
/**
* 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 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_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.
*/
static struct rtc_device *alarmtimer_get_rtcdev(void)
{
struct device *dev;
char *str;
unsigned long flags;
struct rtc_device *ret;
spin_lock_irqsave(&rtcdev_lock, flags);
if (!rtcdev) {
/* Find an rtc device and init the rtc_timer */
dev = class_find_device(rtc_class, NULL, &str, has_wakealarm);
/* If we have a device then str is valid. See has_wakealarm() */
if (dev) {
rtcdev = rtc_class_open(str);
/*
* Drop the reference we got in class_find_device,
* rtc_open takes its own.
*/
put_device(dev);
rtc_timer_init(&rtctimer, NULL, NULL);
}
}
ret = rtcdev;
spin_unlock_irqrestore(&rtcdev_lock, flags);
return ret;
}
#else
#define alarmtimer_get_rtcdev() (0)
#define rtcdev (0)
#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 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_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_base *base = container_of(timer, struct alarm_base, timer);
struct timerqueue_node *next;
unsigned long flags;
ktime_t now;
int ret = HRTIMER_NORESTART;
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_set_expires(&base->timer, next->expires);
ret = HRTIMER_RESTART;
}
spin_unlock_irqrestore(&base->lock, flags);
return ret;
}
#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;
spin_lock_irqsave(&freezer_delta_lock, flags);
min = freezer_delta;
freezer_delta = ktime_set(0, 0);
spin_unlock_irqrestore(&freezer_delta_lock, flags);
rtc = 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;
/* 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(rtc, &rtctimer);
rtc_read_time(rtc, &tm);
now = rtc_tm_to_ktime(tm);
now = ktime_add(now, min);
rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0));
return 0;
}
#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,
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
*/
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
*/
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);
}
/**
* 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 void alarm_handle_timer(struct alarm *alarm)
{
struct k_itimer *ptr = container_of(alarm, struct k_itimer,
it.alarmtimer);
if (posix_timer_event(ptr, 0) != 0)
ptr->it_overrun++;
}
/**
* 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 -ENOTSUPP;
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 -ENOTSUPP;
*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.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.alarmtimer.period);
cur_setting->it_value =
ktime_to_timespec(timr->it.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;
alarm_cancel(&timr->it.alarmtimer);
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)
{
if (!rtcdev)
return -ENOTSUPP;
/*
* XXX HACK! Currently we can DOS a system if the interval
* period on alarmtimers is too small. Cap the interval here
* to 100us and solve this properly in a future patch! -jstultz
*/
if ((new_setting->it_interval.tv_sec == 0) &&
(new_setting->it_interval.tv_nsec < 100000))
new_setting->it_interval.tv_nsec = 100000;
if (old_setting)
alarm_timer_get(timr, old_setting);
/* If the timer was already set, cancel it */
alarm_cancel(&timr->it.alarmtimer);
/* start the timer */
alarm_start(&timr->it.alarmtimer,
timespec_to_ktime(new_setting->it_value),
timespec_to_ktime(new_setting->it_interval));
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 void alarmtimer_nsleep_wakeup(struct alarm *alarm)
{
struct task_struct *task = (struct task_struct *)alarm->data;
alarm->data = NULL;
if (task)
wake_up_process(task);
}
/**
* 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, ktime_set(0, 0));
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 (!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 = ¤t_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)
{
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,
};
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);
hrtimer_init(&alarm_bases[i].timer,
alarm_bases[i].base_clockid,
HRTIMER_MODE_ABS);
alarm_bases[i].timer.function = alarmtimer_fired;
}
error = platform_driver_register(&alarmtimer_driver);
platform_device_register_simple("alarmtimer", -1, NULL, 0);
return error;
}
device_initcall(alarmtimer_init);