WSL2-Linux-Kernel/kernel/time/alarmtimer.c

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C
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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>
/**
* 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);
/**
* 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)
{
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 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
static inline 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) { }
#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);
alarm->state |= ALARMTIMER_STATE_ENQUEUED;
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);
if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
return;
timerqueue_del(&base->timerqueue, &alarm->node);
alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
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;
int restart = ALARMTIMER_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->state &= ~ALARMTIMER_STATE_ENQUEUED;
alarm->state |= ALARMTIMER_STATE_CALLBACK;
spin_unlock_irqrestore(&base->lock, flags);
if (alarm->function)
restart = alarm->function(alarm, now);
spin_lock_irqsave(&base->lock, flags);
alarm->state &= ~ALARMTIMER_STATE_CALLBACK;
if (restart != ALARMTIMER_NORESTART) {
timerqueue_add(&base->timerqueue, &alarm->node);
alarm->state |= ALARMTIMER_STATE_ENQUEUED;
}
}
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 = 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;
/* 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
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
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);
alarm->function = function;
alarm->type = type;
alarm->state = ALARMTIMER_STATE_INACTIVE;
}
/**
* alarm_start - Sets an alarm to fire
* @alarm: ptr to alarm to set
* @start: time to run the alarm
*/
void alarm_start(struct alarm *alarm, ktime_t start)
{
struct alarm_base *base = &alarm_bases[alarm->type];
unsigned long flags;
spin_lock_irqsave(&base->lock, flags);
if (alarmtimer_active(alarm))
alarmtimer_remove(base, alarm);
alarm->node.expires = start;
alarmtimer_enqueue(base, alarm);
spin_unlock_irqrestore(&base->lock, flags);
}
/**
* 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 = -1;
spin_lock_irqsave(&base->lock, flags);
if (alarmtimer_callback_running(alarm))
goto out;
if (alarmtimer_is_queued(alarm)) {
alarmtimer_remove(base, alarm);
ret = 1;
} else
ret = 0;
out:
spin_unlock_irqrestore(&base->lock, flags);
return ret;
}
/**
* 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();
}
}
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;
}
/**
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
* 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;
}
/**
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
* 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)
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
{
struct k_itimer *ptr = container_of(alarm, struct k_itimer,
it.alarm.alarmtimer);
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
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;
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
}
/**
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
* 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;
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
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;
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
*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;
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
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);
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
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));
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
cur_setting->it_interval =
ktime_to_timespec(timr->it.alarm.interval);
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
cur_setting->it_value =
ktime_to_timespec(timr->it.alarm.alarmtimer.node.expires);
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
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;
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
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;
if (old_setting)
alarm_timer_get(timr, old_setting);
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
/* If the timer was already set, cancel it */
if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
return TIMER_RETRY;
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
/* start the timer */
timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
alarm_start(&timr->it.alarm.alarmtimer,
timespec_to_ktime(new_setting->it_value));
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
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)
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
{
struct task_struct *task = (struct task_struct *)alarm->data;
alarm->data = NULL;
if (task)
wake_up_process(task);
return ALARMTIMER_NORESTART;
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
}
/**
* 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);
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
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;
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
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;
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
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;
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
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;
timers: Posix interface for alarm-timers This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ 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 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). 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>
2011-01-11 20:54:33 +03:00
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 = 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;
}
return 0;
out_drv:
platform_driver_unregister(&alarmtimer_driver);
out_if:
alarmtimer_rtc_interface_remove();
return error;
}
device_initcall(alarmtimer_init);