diff options
Diffstat (limited to 'kernel/time/alarmtimer.c')
| -rw-r--r-- | kernel/time/alarmtimer.c | 702 |
1 files changed, 702 insertions, 0 deletions
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c new file mode 100644 index 00000000000..2d966244ea6 --- /dev/null +++ b/kernel/time/alarmtimer.c @@ -0,0 +1,702 @@ +/* + * 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]; + +#ifdef CONFIG_RTC_CLASS +/* rtc timer and device for setting alarm wakeups at suspend */ +static struct rtc_timer rtctimer; +static struct rtc_device *rtcdev; +#endif + +/* freezer delta & lock used to handle clock_nanosleep triggered wakeups */ +static ktime_t freezer_delta; +static DEFINE_SPINLOCK(freezer_delta_lock); + + +/** + * 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; + int i; + + spin_lock_irqsave(&freezer_delta_lock, flags); + min = freezer_delta; + freezer_delta = ktime_set(0, 0); + spin_unlock_irqrestore(&freezer_delta_lock, flags); + + /* If we have no rtcdev, just return */ + if (!rtcdev) + return 0; + + /* Find the soonest timer to expire*/ + for (i = 0; i < ALARM_NUMTYPE; i++) { + struct alarm_base *base = &alarm_bases[i]; + struct timerqueue_node *next; + ktime_t delta; + + spin_lock_irqsave(&base->lock, flags); + next = timerqueue_getnext(&base->timerqueue); + spin_unlock_irqrestore(&base->lock, flags); + if (!next) + continue; + delta = ktime_sub(next->expires, base->gettime()); + if (!min.tv64 || (delta.tv64 < min.tv64)) + min = delta; + } + if (min.tv64 == 0) + return 0; + + /* XXX - Should we enforce a minimum sleep time? */ + WARN_ON(min.tv64 < NSEC_PER_SEC); + + /* Setup an rtc timer to fire that far in the future */ + rtc_timer_cancel(rtcdev, &rtctimer); + rtc_read_time(rtcdev, &tm); + now = rtc_tm_to_ktime(tm); + now = ktime_add(now, min); + + rtc_timer_start(rtcdev, &rtctimer, now, ktime_set(0, 0)); + + return 0; +} +#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; + + 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)]; + + *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 (!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) +{ + 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) +{ + 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) +{ + /* Save old values */ + old_setting->it_interval = + ktime_to_timespec(timr->it.alarmtimer.period); + old_setting->it_value = + ktime_to_timespec(timr->it.alarmtimer.node.expires); + + /* 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 (!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); + +#ifdef CONFIG_RTC_CLASS +/** + * has_wakealarm - check rtc device has wakealarm ability + * @dev: current device + * @name_ptr: name to be returned + * + * This helper function checks to see if the rtc device can wake + * from suspend. + */ +static int __init has_wakealarm(struct device *dev, void *name_ptr) +{ + struct rtc_device *candidate = to_rtc_device(dev); + + if (!candidate->ops->set_alarm) + return 0; + if (!device_may_wakeup(candidate->dev.parent)) + return 0; + + *(const char **)name_ptr = dev_name(dev); + return 1; +} + +/** + * alarmtimer_init_late - Late initializing of alarmtimer code + * + * This function locates a rtc device to use for wakealarms. + * Run as late_initcall to make sure rtc devices have been + * registered. + */ +static int __init alarmtimer_init_late(void) +{ + struct device *dev; + char *str; + + /* 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); + } + if (!rtcdev) { + printk(KERN_WARNING "No RTC device found, ALARM timers will" + " not wake from suspend"); + } + rtc_timer_init(&rtctimer, NULL, NULL); + + return 0; +} +#else +static int __init alarmtimer_init_late(void) +{ + printk(KERN_WARNING "Kernel not built with RTC support, ALARM timers" + " will not wake from suspend"); + return 0; +} +#endif +late_initcall(alarmtimer_init_late); |