/* * 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 * * 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 #include #include #include #include #include #include #include #include #include /** * struct alarm_base - Alarm timer bases * @lock: Lock for syncrhonized access to the base * @timerqueue: Timerqueue head managing the list of events * @timer: hrtimer used to schedule events while running * @gettime: Function to read the time correlating to the base * @base_clockid: clockid for the base */ static struct alarm_base { spinlock_t lock; struct timerqueue_head timerqueue; struct hrtimer timer; ktime_t (*gettime)(void); clockid_t base_clockid; } alarm_bases[ALARM_NUMTYPE]; /* freezer delta & lock used to handle clock_nanosleep triggered wakeups */ static ktime_t freezer_delta; static DEFINE_SPINLOCK(freezer_delta_lock); #ifdef CONFIG_RTC_CLASS /* rtc timer and device for setting alarm wakeups at suspend */ static struct rtc_timer rtctimer; static struct rtc_device *rtcdev; static DEFINE_SPINLOCK(rtcdev_lock); /** * has_wakealarm - check rtc device has wakealarm ability * @dev: current device * @name_ptr: name to be returned * * This helper function checks to see if the rtc device can wake * from suspend. */ static int has_wakealarm(struct device *dev, void *name_ptr) { struct rtc_device *candidate = to_rtc_device(dev); if (!candidate->ops->set_alarm) return 0; if (!device_may_wakeup(candidate->dev.parent)) return 0; *(const char **)name_ptr = dev_name(dev); return 1; } /** * alarmtimer_get_rtcdev - Return selected rtcdevice * * This function returns the rtc device to use for wakealarms. * If one has not already been chosen, it checks to see if a * functional rtc device is available. */ static struct rtc_device *alarmtimer_get_rtcdev(void) { struct device *dev; char *str; unsigned long flags; struct rtc_device *ret; spin_lock_irqsave(&rtcdev_lock, flags); if (!rtcdev) { /* Find an rtc device and init the rtc_timer */ dev = class_find_device(rtc_class, NULL, &str, has_wakealarm); /* If we have a device then str is valid. See has_wakealarm() */ if (dev) { rtcdev = rtc_class_open(str); /* * Drop the reference we got in class_find_device, * rtc_open takes its own. */ put_device(dev); rtc_timer_init(&rtctimer, NULL, NULL); } } ret = rtcdev; spin_unlock_irqrestore(&rtcdev_lock, flags); return ret; } #else #define alarmtimer_get_rtcdev() (0) #define rtcdev (0) #endif /** * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue * @base: pointer to the base where the timer is being run * @alarm: pointer to alarm being enqueued. * * Adds alarm to a alarm_base timerqueue and if necessary sets * an hrtimer to run. * * Must hold base->lock when calling. */ static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm) { timerqueue_add(&base->timerqueue, &alarm->node); 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 = rtcdev; /* If we have no rtcdev, just return */ if (!rtc) return 0; /* Find the soonest timer to expire*/ for (i = 0; i < ALARM_NUMTYPE; i++) { struct alarm_base *base = &alarm_bases[i]; struct timerqueue_node *next; ktime_t delta; spin_lock_irqsave(&base->lock, flags); next = timerqueue_getnext(&base->timerqueue); spin_unlock_irqrestore(&base->lock, flags); if (!next) continue; delta = ktime_sub(next->expires, base->gettime()); if (!min.tv64 || (delta.tv64 < min.tv64)) min = delta; } if (min.tv64 == 0) return 0; /* XXX - Should we enforce a minimum sleep time? */ WARN_ON(min.tv64 < NSEC_PER_SEC); /* Setup an rtc timer to fire that far in the future */ rtc_timer_cancel(rtc, &rtctimer); rtc_read_time(rtc, &tm); now = rtc_tm_to_ktime(tm); now = ktime_add(now, min); rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0)); return 0; } #else static int alarmtimer_suspend(struct device *dev) { return 0; } #endif static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type) { ktime_t delta; unsigned long flags; struct alarm_base *base = &alarm_bases[type]; delta = ktime_sub(absexp, base->gettime()); spin_lock_irqsave(&freezer_delta_lock, flags); if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64)) freezer_delta = delta; spin_unlock_irqrestore(&freezer_delta_lock, flags); } /** * alarm_init - Initialize an alarm structure * @alarm: ptr to alarm to be initialized * @type: the type of the alarm * @function: callback that is run when the alarm fires */ void alarm_init(struct alarm *alarm, enum alarmtimer_type type, 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; } /** * 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 enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm, ktime_t now) { struct k_itimer *ptr = container_of(alarm, struct k_itimer, it.alarm.alarmtimer); 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; } /** * alarm_clock_getres - posix getres interface * @which_clock: clockid * @tp: timespec to fill * * Returns the granularity of underlying alarm base clock */ static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp) { clockid_t baseid = alarm_bases[clock2alarm(which_clock)].base_clockid; if (!alarmtimer_get_rtcdev()) return -ENOTSUPP; return hrtimer_get_res(baseid, tp); } /** * alarm_clock_get - posix clock_get interface * @which_clock: clockid * @tp: timespec to fill. * * Provides the underlying alarm base time. */ static int alarm_clock_get(clockid_t which_clock, struct timespec *tp) { struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)]; if (!alarmtimer_get_rtcdev()) return -ENOTSUPP; *tp = ktime_to_timespec(base->gettime()); return 0; } /** * alarm_timer_create - posix timer_create interface * @new_timer: k_itimer pointer to manage * * Initializes the k_itimer structure. */ static int alarm_timer_create(struct k_itimer *new_timer) { enum alarmtimer_type type; struct alarm_base *base; if (!alarmtimer_get_rtcdev()) return -ENOTSUPP; if (!capable(CAP_WAKE_ALARM)) return -EPERM; type = clock2alarm(new_timer->it_clock); base = &alarm_bases[type]; alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer); return 0; } /** * alarm_timer_get - posix timer_get interface * @new_timer: k_itimer pointer * @cur_setting: itimerspec data to fill * * Copies the itimerspec data out from the k_itimer */ static void alarm_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting) { memset(cur_setting, 0, sizeof(struct itimerspec)); cur_setting->it_interval = ktime_to_timespec(timr->it.alarm.interval); cur_setting->it_value = ktime_to_timespec(timr->it.alarm.alarmtimer.node.expires); return; } /** * alarm_timer_del - posix timer_del interface * @timr: k_itimer pointer to be deleted * * Cancels any programmed alarms for the given timer. */ static int alarm_timer_del(struct k_itimer *timr) { if (!rtcdev) return -ENOTSUPP; if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0) return TIMER_RETRY; 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); /* If the timer was already set, cancel it */ if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0) return TIMER_RETRY; /* 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)); 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) { struct task_struct *task = (struct task_struct *)alarm->data; alarm->data = NULL; if (task) wake_up_process(task); return ALARMTIMER_NORESTART; } /** * 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); if (likely(alarm->data)) schedule(); alarm_cancel(alarm); } while (alarm->data && !signal_pending(current)); __set_current_state(TASK_RUNNING); return (alarm->data == NULL); } /** * update_rmtp - Update remaining timespec value * @exp: expiration time * @type: timer type * @rmtp: user pointer to remaining timepsec value * * Helper function that fills in rmtp value with time between * now and the exp value */ static int update_rmtp(ktime_t exp, enum alarmtimer_type type, struct timespec __user *rmtp) { struct timespec rmt; ktime_t rem; rem = ktime_sub(exp, alarm_bases[type].gettime()); if (rem.tv64 <= 0) return 0; rmt = ktime_to_timespec(rem); if (copy_to_user(rmtp, &rmt, sizeof(*rmtp))) return -EFAULT; return 1; } /** * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep * @restart: ptr to restart block * * Handles restarted clock_nanosleep calls */ static long __sched alarm_timer_nsleep_restart(struct restart_block *restart) { enum alarmtimer_type type = restart->nanosleep.clockid; ktime_t exp; struct timespec __user *rmtp; struct alarm alarm; int ret = 0; exp.tv64 = restart->nanosleep.expires; alarm_init(&alarm, type, alarmtimer_nsleep_wakeup); if (alarmtimer_do_nsleep(&alarm, exp)) goto out; if (freezing(current)) alarmtimer_freezerset(exp, type); rmtp = restart->nanosleep.rmtp; if (rmtp) { ret = update_rmtp(exp, type, rmtp); if (ret <= 0) goto out; } /* The other values in restart are already filled in */ ret = -ERESTART_RESTARTBLOCK; out: return ret; } /** * alarm_timer_nsleep - alarmtimer nanosleep * @which_clock: clockid * @flags: determins abstime or relative * @tsreq: requested sleep time (abs or rel) * @rmtp: remaining sleep time saved * * Handles clock_nanosleep calls against _ALARM clockids */ static int alarm_timer_nsleep(const clockid_t which_clock, int flags, struct timespec *tsreq, struct timespec __user *rmtp) { enum alarmtimer_type type = clock2alarm(which_clock); struct alarm alarm; ktime_t exp; int ret = 0; struct restart_block *restart; if (!alarmtimer_get_rtcdev()) return -ENOTSUPP; if (!capable(CAP_WAKE_ALARM)) return -EPERM; alarm_init(&alarm, type, alarmtimer_nsleep_wakeup); exp = timespec_to_ktime(*tsreq); /* Convert (if necessary) to absolute time */ if (flags != TIMER_ABSTIME) { ktime_t now = alarm_bases[type].gettime(); exp = ktime_add(now, exp); } if (alarmtimer_do_nsleep(&alarm, exp)) goto out; if (freezing(current)) alarmtimer_freezerset(exp, type); /* abs timers don't set remaining time or restart */ if (flags == TIMER_ABSTIME) { ret = -ERESTARTNOHAND; goto out; } if (rmtp) { ret = update_rmtp(exp, type, rmtp); if (ret <= 0) goto out; } restart = ¤t_thread_info()->restart_block; restart->fn = alarm_timer_nsleep_restart; restart->nanosleep.clockid = type; restart->nanosleep.expires = exp.tv64; restart->nanosleep.rmtp = rmtp; ret = -ERESTART_RESTARTBLOCK; out: return ret; } /* Suspend hook structures */ static const struct dev_pm_ops alarmtimer_pm_ops = { .suspend = alarmtimer_suspend, }; static struct platform_driver alarmtimer_driver = { .driver = { .name = "alarmtimer", .pm = &alarmtimer_pm_ops, } }; /** * alarmtimer_init - Initialize alarm timer code * * This function initializes the alarm bases and registers * the posix clock ids. */ static int __init alarmtimer_init(void) { int error = 0; int i; struct k_clock alarm_clock = { .clock_getres = alarm_clock_getres, .clock_get = alarm_clock_get, .timer_create = alarm_timer_create, .timer_set = alarm_timer_set, .timer_del = alarm_timer_del, .timer_get = alarm_timer_get, .nsleep = alarm_timer_nsleep, }; posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock); posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock); /* Initialize alarm bases */ alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME; alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real; alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME; alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime; for (i = 0; i < ALARM_NUMTYPE; i++) { timerqueue_init_head(&alarm_bases[i].timerqueue); spin_lock_init(&alarm_bases[i].lock); hrtimer_init(&alarm_bases[i].timer, alarm_bases[i].base_clockid, HRTIMER_MODE_ABS); alarm_bases[i].timer.function = alarmtimer_fired; } error = platform_driver_register(&alarmtimer_driver); platform_device_register_simple("alarmtimer", -1, NULL, 0); return error; } device_initcall(alarmtimer_init);