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0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Alarmtimer interface
0004  *
0005  * This interface provides a timer which is similar to hrtimers,
0006  * but triggers a RTC alarm if the box is suspend.
0007  *
0008  * This interface is influenced by the Android RTC Alarm timer
0009  * interface.
0010  *
0011  * Copyright (C) 2010 IBM Corporation
0012  *
0013  * Author: John Stultz <john.stultz@linaro.org>
0014  */
0015 #include <linux/time.h>
0016 #include <linux/hrtimer.h>
0017 #include <linux/timerqueue.h>
0018 #include <linux/rtc.h>
0019 #include <linux/sched/signal.h>
0020 #include <linux/sched/debug.h>
0021 #include <linux/alarmtimer.h>
0022 #include <linux/mutex.h>
0023 #include <linux/platform_device.h>
0024 #include <linux/posix-timers.h>
0025 #include <linux/workqueue.h>
0026 #include <linux/freezer.h>
0027 #include <linux/compat.h>
0028 #include <linux/module.h>
0029 #include <linux/time_namespace.h>
0030 
0031 #include "posix-timers.h"
0032 
0033 #define CREATE_TRACE_POINTS
0034 #include <trace/events/alarmtimer.h>
0035 
0036 /**
0037  * struct alarm_base - Alarm timer bases
0038  * @lock:       Lock for syncrhonized access to the base
0039  * @timerqueue:     Timerqueue head managing the list of events
0040  * @get_ktime:      Function to read the time correlating to the base
0041  * @get_timespec:   Function to read the namespace time correlating to the base
0042  * @base_clockid:   clockid for the base
0043  */
0044 static struct alarm_base {
0045     spinlock_t      lock;
0046     struct timerqueue_head  timerqueue;
0047     ktime_t         (*get_ktime)(void);
0048     void            (*get_timespec)(struct timespec64 *tp);
0049     clockid_t       base_clockid;
0050 } alarm_bases[ALARM_NUMTYPE];
0051 
0052 #if defined(CONFIG_POSIX_TIMERS) || defined(CONFIG_RTC_CLASS)
0053 /* freezer information to handle clock_nanosleep triggered wakeups */
0054 static enum alarmtimer_type freezer_alarmtype;
0055 static ktime_t freezer_expires;
0056 static ktime_t freezer_delta;
0057 static DEFINE_SPINLOCK(freezer_delta_lock);
0058 #endif
0059 
0060 #ifdef CONFIG_RTC_CLASS
0061 /* rtc timer and device for setting alarm wakeups at suspend */
0062 static struct rtc_timer     rtctimer;
0063 static struct rtc_device    *rtcdev;
0064 static DEFINE_SPINLOCK(rtcdev_lock);
0065 
0066 /**
0067  * alarmtimer_get_rtcdev - Return selected rtcdevice
0068  *
0069  * This function returns the rtc device to use for wakealarms.
0070  */
0071 struct rtc_device *alarmtimer_get_rtcdev(void)
0072 {
0073     unsigned long flags;
0074     struct rtc_device *ret;
0075 
0076     spin_lock_irqsave(&rtcdev_lock, flags);
0077     ret = rtcdev;
0078     spin_unlock_irqrestore(&rtcdev_lock, flags);
0079 
0080     return ret;
0081 }
0082 EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
0083 
0084 static int alarmtimer_rtc_add_device(struct device *dev,
0085                 struct class_interface *class_intf)
0086 {
0087     unsigned long flags;
0088     struct rtc_device *rtc = to_rtc_device(dev);
0089     struct platform_device *pdev;
0090     int ret = 0;
0091 
0092     if (rtcdev)
0093         return -EBUSY;
0094 
0095     if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
0096         return -1;
0097     if (!device_may_wakeup(rtc->dev.parent))
0098         return -1;
0099 
0100     pdev = platform_device_register_data(dev, "alarmtimer",
0101                          PLATFORM_DEVID_AUTO, NULL, 0);
0102     if (!IS_ERR(pdev))
0103         device_init_wakeup(&pdev->dev, true);
0104 
0105     spin_lock_irqsave(&rtcdev_lock, flags);
0106     if (!IS_ERR(pdev) && !rtcdev) {
0107         if (!try_module_get(rtc->owner)) {
0108             ret = -1;
0109             goto unlock;
0110         }
0111 
0112         rtcdev = rtc;
0113         /* hold a reference so it doesn't go away */
0114         get_device(dev);
0115         pdev = NULL;
0116     } else {
0117         ret = -1;
0118     }
0119 unlock:
0120     spin_unlock_irqrestore(&rtcdev_lock, flags);
0121 
0122     platform_device_unregister(pdev);
0123 
0124     return ret;
0125 }
0126 
0127 static inline void alarmtimer_rtc_timer_init(void)
0128 {
0129     rtc_timer_init(&rtctimer, NULL, NULL);
0130 }
0131 
0132 static struct class_interface alarmtimer_rtc_interface = {
0133     .add_dev = &alarmtimer_rtc_add_device,
0134 };
0135 
0136 static int alarmtimer_rtc_interface_setup(void)
0137 {
0138     alarmtimer_rtc_interface.class = rtc_class;
0139     return class_interface_register(&alarmtimer_rtc_interface);
0140 }
0141 static void alarmtimer_rtc_interface_remove(void)
0142 {
0143     class_interface_unregister(&alarmtimer_rtc_interface);
0144 }
0145 #else
0146 static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
0147 static inline void alarmtimer_rtc_interface_remove(void) { }
0148 static inline void alarmtimer_rtc_timer_init(void) { }
0149 #endif
0150 
0151 /**
0152  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
0153  * @base: pointer to the base where the timer is being run
0154  * @alarm: pointer to alarm being enqueued.
0155  *
0156  * Adds alarm to a alarm_base timerqueue
0157  *
0158  * Must hold base->lock when calling.
0159  */
0160 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
0161 {
0162     if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
0163         timerqueue_del(&base->timerqueue, &alarm->node);
0164 
0165     timerqueue_add(&base->timerqueue, &alarm->node);
0166     alarm->state |= ALARMTIMER_STATE_ENQUEUED;
0167 }
0168 
0169 /**
0170  * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
0171  * @base: pointer to the base where the timer is running
0172  * @alarm: pointer to alarm being removed
0173  *
0174  * Removes alarm to a alarm_base timerqueue
0175  *
0176  * Must hold base->lock when calling.
0177  */
0178 static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
0179 {
0180     if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
0181         return;
0182 
0183     timerqueue_del(&base->timerqueue, &alarm->node);
0184     alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
0185 }
0186 
0187 
0188 /**
0189  * alarmtimer_fired - Handles alarm hrtimer being fired.
0190  * @timer: pointer to hrtimer being run
0191  *
0192  * When a alarm timer fires, this runs through the timerqueue to
0193  * see which alarms expired, and runs those. If there are more alarm
0194  * timers queued for the future, we set the hrtimer to fire when
0195  * the next future alarm timer expires.
0196  */
0197 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
0198 {
0199     struct alarm *alarm = container_of(timer, struct alarm, timer);
0200     struct alarm_base *base = &alarm_bases[alarm->type];
0201     unsigned long flags;
0202     int ret = HRTIMER_NORESTART;
0203     int restart = ALARMTIMER_NORESTART;
0204 
0205     spin_lock_irqsave(&base->lock, flags);
0206     alarmtimer_dequeue(base, alarm);
0207     spin_unlock_irqrestore(&base->lock, flags);
0208 
0209     if (alarm->function)
0210         restart = alarm->function(alarm, base->get_ktime());
0211 
0212     spin_lock_irqsave(&base->lock, flags);
0213     if (restart != ALARMTIMER_NORESTART) {
0214         hrtimer_set_expires(&alarm->timer, alarm->node.expires);
0215         alarmtimer_enqueue(base, alarm);
0216         ret = HRTIMER_RESTART;
0217     }
0218     spin_unlock_irqrestore(&base->lock, flags);
0219 
0220     trace_alarmtimer_fired(alarm, base->get_ktime());
0221     return ret;
0222 
0223 }
0224 
0225 ktime_t alarm_expires_remaining(const struct alarm *alarm)
0226 {
0227     struct alarm_base *base = &alarm_bases[alarm->type];
0228     return ktime_sub(alarm->node.expires, base->get_ktime());
0229 }
0230 EXPORT_SYMBOL_GPL(alarm_expires_remaining);
0231 
0232 #ifdef CONFIG_RTC_CLASS
0233 /**
0234  * alarmtimer_suspend - Suspend time callback
0235  * @dev: unused
0236  *
0237  * When we are going into suspend, we look through the bases
0238  * to see which is the soonest timer to expire. We then
0239  * set an rtc timer to fire that far into the future, which
0240  * will wake us from suspend.
0241  */
0242 static int alarmtimer_suspend(struct device *dev)
0243 {
0244     ktime_t min, now, expires;
0245     int i, ret, type;
0246     struct rtc_device *rtc;
0247     unsigned long flags;
0248     struct rtc_time tm;
0249 
0250     spin_lock_irqsave(&freezer_delta_lock, flags);
0251     min = freezer_delta;
0252     expires = freezer_expires;
0253     type = freezer_alarmtype;
0254     freezer_delta = 0;
0255     spin_unlock_irqrestore(&freezer_delta_lock, flags);
0256 
0257     rtc = alarmtimer_get_rtcdev();
0258     /* If we have no rtcdev, just return */
0259     if (!rtc)
0260         return 0;
0261 
0262     /* Find the soonest timer to expire*/
0263     for (i = 0; i < ALARM_NUMTYPE; i++) {
0264         struct alarm_base *base = &alarm_bases[i];
0265         struct timerqueue_node *next;
0266         ktime_t delta;
0267 
0268         spin_lock_irqsave(&base->lock, flags);
0269         next = timerqueue_getnext(&base->timerqueue);
0270         spin_unlock_irqrestore(&base->lock, flags);
0271         if (!next)
0272             continue;
0273         delta = ktime_sub(next->expires, base->get_ktime());
0274         if (!min || (delta < min)) {
0275             expires = next->expires;
0276             min = delta;
0277             type = i;
0278         }
0279     }
0280     if (min == 0)
0281         return 0;
0282 
0283     if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
0284         pm_wakeup_event(dev, 2 * MSEC_PER_SEC);
0285         return -EBUSY;
0286     }
0287 
0288     trace_alarmtimer_suspend(expires, type);
0289 
0290     /* Setup an rtc timer to fire that far in the future */
0291     rtc_timer_cancel(rtc, &rtctimer);
0292     rtc_read_time(rtc, &tm);
0293     now = rtc_tm_to_ktime(tm);
0294     now = ktime_add(now, min);
0295 
0296     /* Set alarm, if in the past reject suspend briefly to handle */
0297     ret = rtc_timer_start(rtc, &rtctimer, now, 0);
0298     if (ret < 0)
0299         pm_wakeup_event(dev, MSEC_PER_SEC);
0300     return ret;
0301 }
0302 
0303 static int alarmtimer_resume(struct device *dev)
0304 {
0305     struct rtc_device *rtc;
0306 
0307     rtc = alarmtimer_get_rtcdev();
0308     if (rtc)
0309         rtc_timer_cancel(rtc, &rtctimer);
0310     return 0;
0311 }
0312 
0313 #else
0314 static int alarmtimer_suspend(struct device *dev)
0315 {
0316     return 0;
0317 }
0318 
0319 static int alarmtimer_resume(struct device *dev)
0320 {
0321     return 0;
0322 }
0323 #endif
0324 
0325 static void
0326 __alarm_init(struct alarm *alarm, enum alarmtimer_type type,
0327          enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
0328 {
0329     timerqueue_init(&alarm->node);
0330     alarm->timer.function = alarmtimer_fired;
0331     alarm->function = function;
0332     alarm->type = type;
0333     alarm->state = ALARMTIMER_STATE_INACTIVE;
0334 }
0335 
0336 /**
0337  * alarm_init - Initialize an alarm structure
0338  * @alarm: ptr to alarm to be initialized
0339  * @type: the type of the alarm
0340  * @function: callback that is run when the alarm fires
0341  */
0342 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
0343         enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
0344 {
0345     hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
0346              HRTIMER_MODE_ABS);
0347     __alarm_init(alarm, type, function);
0348 }
0349 EXPORT_SYMBOL_GPL(alarm_init);
0350 
0351 /**
0352  * alarm_start - Sets an absolute alarm to fire
0353  * @alarm: ptr to alarm to set
0354  * @start: time to run the alarm
0355  */
0356 void alarm_start(struct alarm *alarm, ktime_t start)
0357 {
0358     struct alarm_base *base = &alarm_bases[alarm->type];
0359     unsigned long flags;
0360 
0361     spin_lock_irqsave(&base->lock, flags);
0362     alarm->node.expires = start;
0363     alarmtimer_enqueue(base, alarm);
0364     hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
0365     spin_unlock_irqrestore(&base->lock, flags);
0366 
0367     trace_alarmtimer_start(alarm, base->get_ktime());
0368 }
0369 EXPORT_SYMBOL_GPL(alarm_start);
0370 
0371 /**
0372  * alarm_start_relative - Sets a relative alarm to fire
0373  * @alarm: ptr to alarm to set
0374  * @start: time relative to now to run the alarm
0375  */
0376 void alarm_start_relative(struct alarm *alarm, ktime_t start)
0377 {
0378     struct alarm_base *base = &alarm_bases[alarm->type];
0379 
0380     start = ktime_add_safe(start, base->get_ktime());
0381     alarm_start(alarm, start);
0382 }
0383 EXPORT_SYMBOL_GPL(alarm_start_relative);
0384 
0385 void alarm_restart(struct alarm *alarm)
0386 {
0387     struct alarm_base *base = &alarm_bases[alarm->type];
0388     unsigned long flags;
0389 
0390     spin_lock_irqsave(&base->lock, flags);
0391     hrtimer_set_expires(&alarm->timer, alarm->node.expires);
0392     hrtimer_restart(&alarm->timer);
0393     alarmtimer_enqueue(base, alarm);
0394     spin_unlock_irqrestore(&base->lock, flags);
0395 }
0396 EXPORT_SYMBOL_GPL(alarm_restart);
0397 
0398 /**
0399  * alarm_try_to_cancel - Tries to cancel an alarm timer
0400  * @alarm: ptr to alarm to be canceled
0401  *
0402  * Returns 1 if the timer was canceled, 0 if it was not running,
0403  * and -1 if the callback was running
0404  */
0405 int alarm_try_to_cancel(struct alarm *alarm)
0406 {
0407     struct alarm_base *base = &alarm_bases[alarm->type];
0408     unsigned long flags;
0409     int ret;
0410 
0411     spin_lock_irqsave(&base->lock, flags);
0412     ret = hrtimer_try_to_cancel(&alarm->timer);
0413     if (ret >= 0)
0414         alarmtimer_dequeue(base, alarm);
0415     spin_unlock_irqrestore(&base->lock, flags);
0416 
0417     trace_alarmtimer_cancel(alarm, base->get_ktime());
0418     return ret;
0419 }
0420 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
0421 
0422 
0423 /**
0424  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
0425  * @alarm: ptr to alarm to be canceled
0426  *
0427  * Returns 1 if the timer was canceled, 0 if it was not active.
0428  */
0429 int alarm_cancel(struct alarm *alarm)
0430 {
0431     for (;;) {
0432         int ret = alarm_try_to_cancel(alarm);
0433         if (ret >= 0)
0434             return ret;
0435         hrtimer_cancel_wait_running(&alarm->timer);
0436     }
0437 }
0438 EXPORT_SYMBOL_GPL(alarm_cancel);
0439 
0440 
0441 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
0442 {
0443     u64 overrun = 1;
0444     ktime_t delta;
0445 
0446     delta = ktime_sub(now, alarm->node.expires);
0447 
0448     if (delta < 0)
0449         return 0;
0450 
0451     if (unlikely(delta >= interval)) {
0452         s64 incr = ktime_to_ns(interval);
0453 
0454         overrun = ktime_divns(delta, incr);
0455 
0456         alarm->node.expires = ktime_add_ns(alarm->node.expires,
0457                             incr*overrun);
0458 
0459         if (alarm->node.expires > now)
0460             return overrun;
0461         /*
0462          * This (and the ktime_add() below) is the
0463          * correction for exact:
0464          */
0465         overrun++;
0466     }
0467 
0468     alarm->node.expires = ktime_add_safe(alarm->node.expires, interval);
0469     return overrun;
0470 }
0471 EXPORT_SYMBOL_GPL(alarm_forward);
0472 
0473 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
0474 {
0475     struct alarm_base *base = &alarm_bases[alarm->type];
0476 
0477     return alarm_forward(alarm, base->get_ktime(), interval);
0478 }
0479 EXPORT_SYMBOL_GPL(alarm_forward_now);
0480 
0481 #ifdef CONFIG_POSIX_TIMERS
0482 
0483 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
0484 {
0485     struct alarm_base *base;
0486     unsigned long flags;
0487     ktime_t delta;
0488 
0489     switch(type) {
0490     case ALARM_REALTIME:
0491         base = &alarm_bases[ALARM_REALTIME];
0492         type = ALARM_REALTIME_FREEZER;
0493         break;
0494     case ALARM_BOOTTIME:
0495         base = &alarm_bases[ALARM_BOOTTIME];
0496         type = ALARM_BOOTTIME_FREEZER;
0497         break;
0498     default:
0499         WARN_ONCE(1, "Invalid alarm type: %d\n", type);
0500         return;
0501     }
0502 
0503     delta = ktime_sub(absexp, base->get_ktime());
0504 
0505     spin_lock_irqsave(&freezer_delta_lock, flags);
0506     if (!freezer_delta || (delta < freezer_delta)) {
0507         freezer_delta = delta;
0508         freezer_expires = absexp;
0509         freezer_alarmtype = type;
0510     }
0511     spin_unlock_irqrestore(&freezer_delta_lock, flags);
0512 }
0513 
0514 /**
0515  * clock2alarm - helper that converts from clockid to alarmtypes
0516  * @clockid: clockid.
0517  */
0518 static enum alarmtimer_type clock2alarm(clockid_t clockid)
0519 {
0520     if (clockid == CLOCK_REALTIME_ALARM)
0521         return ALARM_REALTIME;
0522     if (clockid == CLOCK_BOOTTIME_ALARM)
0523         return ALARM_BOOTTIME;
0524     return -1;
0525 }
0526 
0527 /**
0528  * alarm_handle_timer - Callback for posix timers
0529  * @alarm: alarm that fired
0530  * @now: time at the timer expiration
0531  *
0532  * Posix timer callback for expired alarm timers.
0533  *
0534  * Return: whether the timer is to be restarted
0535  */
0536 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
0537                             ktime_t now)
0538 {
0539     struct k_itimer *ptr = container_of(alarm, struct k_itimer,
0540                         it.alarm.alarmtimer);
0541     enum alarmtimer_restart result = ALARMTIMER_NORESTART;
0542     unsigned long flags;
0543     int si_private = 0;
0544 
0545     spin_lock_irqsave(&ptr->it_lock, flags);
0546 
0547     ptr->it_active = 0;
0548     if (ptr->it_interval)
0549         si_private = ++ptr->it_requeue_pending;
0550 
0551     if (posix_timer_event(ptr, si_private) && ptr->it_interval) {
0552         /*
0553          * Handle ignored signals and rearm the timer. This will go
0554          * away once we handle ignored signals proper.
0555          */
0556         ptr->it_overrun += alarm_forward_now(alarm, ptr->it_interval);
0557         ++ptr->it_requeue_pending;
0558         ptr->it_active = 1;
0559         result = ALARMTIMER_RESTART;
0560     }
0561     spin_unlock_irqrestore(&ptr->it_lock, flags);
0562 
0563     return result;
0564 }
0565 
0566 /**
0567  * alarm_timer_rearm - Posix timer callback for rearming timer
0568  * @timr:   Pointer to the posixtimer data struct
0569  */
0570 static void alarm_timer_rearm(struct k_itimer *timr)
0571 {
0572     struct alarm *alarm = &timr->it.alarm.alarmtimer;
0573 
0574     timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
0575     alarm_start(alarm, alarm->node.expires);
0576 }
0577 
0578 /**
0579  * alarm_timer_forward - Posix timer callback for forwarding timer
0580  * @timr:   Pointer to the posixtimer data struct
0581  * @now:    Current time to forward the timer against
0582  */
0583 static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
0584 {
0585     struct alarm *alarm = &timr->it.alarm.alarmtimer;
0586 
0587     return alarm_forward(alarm, timr->it_interval, now);
0588 }
0589 
0590 /**
0591  * alarm_timer_remaining - Posix timer callback to retrieve remaining time
0592  * @timr:   Pointer to the posixtimer data struct
0593  * @now:    Current time to calculate against
0594  */
0595 static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
0596 {
0597     struct alarm *alarm = &timr->it.alarm.alarmtimer;
0598 
0599     return ktime_sub(alarm->node.expires, now);
0600 }
0601 
0602 /**
0603  * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
0604  * @timr:   Pointer to the posixtimer data struct
0605  */
0606 static int alarm_timer_try_to_cancel(struct k_itimer *timr)
0607 {
0608     return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
0609 }
0610 
0611 /**
0612  * alarm_timer_wait_running - Posix timer callback to wait for a timer
0613  * @timr:   Pointer to the posixtimer data struct
0614  *
0615  * Called from the core code when timer cancel detected that the callback
0616  * is running. @timr is unlocked and rcu read lock is held to prevent it
0617  * from being freed.
0618  */
0619 static void alarm_timer_wait_running(struct k_itimer *timr)
0620 {
0621     hrtimer_cancel_wait_running(&timr->it.alarm.alarmtimer.timer);
0622 }
0623 
0624 /**
0625  * alarm_timer_arm - Posix timer callback to arm a timer
0626  * @timr:   Pointer to the posixtimer data struct
0627  * @expires:    The new expiry time
0628  * @absolute:   Expiry value is absolute time
0629  * @sigev_none: Posix timer does not deliver signals
0630  */
0631 static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
0632                 bool absolute, bool sigev_none)
0633 {
0634     struct alarm *alarm = &timr->it.alarm.alarmtimer;
0635     struct alarm_base *base = &alarm_bases[alarm->type];
0636 
0637     if (!absolute)
0638         expires = ktime_add_safe(expires, base->get_ktime());
0639     if (sigev_none)
0640         alarm->node.expires = expires;
0641     else
0642         alarm_start(&timr->it.alarm.alarmtimer, expires);
0643 }
0644 
0645 /**
0646  * alarm_clock_getres - posix getres interface
0647  * @which_clock: clockid
0648  * @tp: timespec to fill
0649  *
0650  * Returns the granularity of underlying alarm base clock
0651  */
0652 static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
0653 {
0654     if (!alarmtimer_get_rtcdev())
0655         return -EINVAL;
0656 
0657     tp->tv_sec = 0;
0658     tp->tv_nsec = hrtimer_resolution;
0659     return 0;
0660 }
0661 
0662 /**
0663  * alarm_clock_get_timespec - posix clock_get_timespec interface
0664  * @which_clock: clockid
0665  * @tp: timespec to fill.
0666  *
0667  * Provides the underlying alarm base time in a tasks time namespace.
0668  */
0669 static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
0670 {
0671     struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
0672 
0673     if (!alarmtimer_get_rtcdev())
0674         return -EINVAL;
0675 
0676     base->get_timespec(tp);
0677 
0678     return 0;
0679 }
0680 
0681 /**
0682  * alarm_clock_get_ktime - posix clock_get_ktime interface
0683  * @which_clock: clockid
0684  *
0685  * Provides the underlying alarm base time in the root namespace.
0686  */
0687 static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
0688 {
0689     struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
0690 
0691     if (!alarmtimer_get_rtcdev())
0692         return -EINVAL;
0693 
0694     return base->get_ktime();
0695 }
0696 
0697 /**
0698  * alarm_timer_create - posix timer_create interface
0699  * @new_timer: k_itimer pointer to manage
0700  *
0701  * Initializes the k_itimer structure.
0702  */
0703 static int alarm_timer_create(struct k_itimer *new_timer)
0704 {
0705     enum  alarmtimer_type type;
0706 
0707     if (!alarmtimer_get_rtcdev())
0708         return -EOPNOTSUPP;
0709 
0710     if (!capable(CAP_WAKE_ALARM))
0711         return -EPERM;
0712 
0713     type = clock2alarm(new_timer->it_clock);
0714     alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
0715     return 0;
0716 }
0717 
0718 /**
0719  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
0720  * @alarm: ptr to alarm that fired
0721  * @now: time at the timer expiration
0722  *
0723  * Wakes up the task that set the alarmtimer
0724  *
0725  * Return: ALARMTIMER_NORESTART
0726  */
0727 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
0728                                 ktime_t now)
0729 {
0730     struct task_struct *task = (struct task_struct *)alarm->data;
0731 
0732     alarm->data = NULL;
0733     if (task)
0734         wake_up_process(task);
0735     return ALARMTIMER_NORESTART;
0736 }
0737 
0738 /**
0739  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
0740  * @alarm: ptr to alarmtimer
0741  * @absexp: absolute expiration time
0742  * @type: alarm type (BOOTTIME/REALTIME).
0743  *
0744  * Sets the alarm timer and sleeps until it is fired or interrupted.
0745  */
0746 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
0747                 enum alarmtimer_type type)
0748 {
0749     struct restart_block *restart;
0750     alarm->data = (void *)current;
0751     do {
0752         set_current_state(TASK_INTERRUPTIBLE);
0753         alarm_start(alarm, absexp);
0754         if (likely(alarm->data))
0755             schedule();
0756 
0757         alarm_cancel(alarm);
0758     } while (alarm->data && !signal_pending(current));
0759 
0760     __set_current_state(TASK_RUNNING);
0761 
0762     destroy_hrtimer_on_stack(&alarm->timer);
0763 
0764     if (!alarm->data)
0765         return 0;
0766 
0767     if (freezing(current))
0768         alarmtimer_freezerset(absexp, type);
0769     restart = &current->restart_block;
0770     if (restart->nanosleep.type != TT_NONE) {
0771         struct timespec64 rmt;
0772         ktime_t rem;
0773 
0774         rem = ktime_sub(absexp, alarm_bases[type].get_ktime());
0775 
0776         if (rem <= 0)
0777             return 0;
0778         rmt = ktime_to_timespec64(rem);
0779 
0780         return nanosleep_copyout(restart, &rmt);
0781     }
0782     return -ERESTART_RESTARTBLOCK;
0783 }
0784 
0785 static void
0786 alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
0787             enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
0788 {
0789     hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid,
0790                   HRTIMER_MODE_ABS);
0791     __alarm_init(alarm, type, function);
0792 }
0793 
0794 /**
0795  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
0796  * @restart: ptr to restart block
0797  *
0798  * Handles restarted clock_nanosleep calls
0799  */
0800 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
0801 {
0802     enum  alarmtimer_type type = restart->nanosleep.clockid;
0803     ktime_t exp = restart->nanosleep.expires;
0804     struct alarm alarm;
0805 
0806     alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
0807 
0808     return alarmtimer_do_nsleep(&alarm, exp, type);
0809 }
0810 
0811 /**
0812  * alarm_timer_nsleep - alarmtimer nanosleep
0813  * @which_clock: clockid
0814  * @flags: determines abstime or relative
0815  * @tsreq: requested sleep time (abs or rel)
0816  *
0817  * Handles clock_nanosleep calls against _ALARM clockids
0818  */
0819 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
0820                   const struct timespec64 *tsreq)
0821 {
0822     enum  alarmtimer_type type = clock2alarm(which_clock);
0823     struct restart_block *restart = &current->restart_block;
0824     struct alarm alarm;
0825     ktime_t exp;
0826     int ret = 0;
0827 
0828     if (!alarmtimer_get_rtcdev())
0829         return -EOPNOTSUPP;
0830 
0831     if (flags & ~TIMER_ABSTIME)
0832         return -EINVAL;
0833 
0834     if (!capable(CAP_WAKE_ALARM))
0835         return -EPERM;
0836 
0837     alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
0838 
0839     exp = timespec64_to_ktime(*tsreq);
0840     /* Convert (if necessary) to absolute time */
0841     if (flags != TIMER_ABSTIME) {
0842         ktime_t now = alarm_bases[type].get_ktime();
0843 
0844         exp = ktime_add_safe(now, exp);
0845     } else {
0846         exp = timens_ktime_to_host(which_clock, exp);
0847     }
0848 
0849     ret = alarmtimer_do_nsleep(&alarm, exp, type);
0850     if (ret != -ERESTART_RESTARTBLOCK)
0851         return ret;
0852 
0853     /* abs timers don't set remaining time or restart */
0854     if (flags == TIMER_ABSTIME)
0855         return -ERESTARTNOHAND;
0856 
0857     restart->nanosleep.clockid = type;
0858     restart->nanosleep.expires = exp;
0859     set_restart_fn(restart, alarm_timer_nsleep_restart);
0860     return ret;
0861 }
0862 
0863 const struct k_clock alarm_clock = {
0864     .clock_getres       = alarm_clock_getres,
0865     .clock_get_ktime    = alarm_clock_get_ktime,
0866     .clock_get_timespec = alarm_clock_get_timespec,
0867     .timer_create       = alarm_timer_create,
0868     .timer_set      = common_timer_set,
0869     .timer_del      = common_timer_del,
0870     .timer_get      = common_timer_get,
0871     .timer_arm      = alarm_timer_arm,
0872     .timer_rearm        = alarm_timer_rearm,
0873     .timer_forward      = alarm_timer_forward,
0874     .timer_remaining    = alarm_timer_remaining,
0875     .timer_try_to_cancel    = alarm_timer_try_to_cancel,
0876     .timer_wait_running = alarm_timer_wait_running,
0877     .nsleep         = alarm_timer_nsleep,
0878 };
0879 #endif /* CONFIG_POSIX_TIMERS */
0880 
0881 
0882 /* Suspend hook structures */
0883 static const struct dev_pm_ops alarmtimer_pm_ops = {
0884     .suspend = alarmtimer_suspend,
0885     .resume = alarmtimer_resume,
0886 };
0887 
0888 static struct platform_driver alarmtimer_driver = {
0889     .driver = {
0890         .name = "alarmtimer",
0891         .pm = &alarmtimer_pm_ops,
0892     }
0893 };
0894 
0895 static void get_boottime_timespec(struct timespec64 *tp)
0896 {
0897     ktime_get_boottime_ts64(tp);
0898     timens_add_boottime(tp);
0899 }
0900 
0901 /**
0902  * alarmtimer_init - Initialize alarm timer code
0903  *
0904  * This function initializes the alarm bases and registers
0905  * the posix clock ids.
0906  */
0907 static int __init alarmtimer_init(void)
0908 {
0909     int error;
0910     int i;
0911 
0912     alarmtimer_rtc_timer_init();
0913 
0914     /* Initialize alarm bases */
0915     alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
0916     alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
0917     alarm_bases[ALARM_REALTIME].get_timespec = ktime_get_real_ts64;
0918     alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
0919     alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
0920     alarm_bases[ALARM_BOOTTIME].get_timespec = get_boottime_timespec;
0921     for (i = 0; i < ALARM_NUMTYPE; i++) {
0922         timerqueue_init_head(&alarm_bases[i].timerqueue);
0923         spin_lock_init(&alarm_bases[i].lock);
0924     }
0925 
0926     error = alarmtimer_rtc_interface_setup();
0927     if (error)
0928         return error;
0929 
0930     error = platform_driver_register(&alarmtimer_driver);
0931     if (error)
0932         goto out_if;
0933 
0934     return 0;
0935 out_if:
0936     alarmtimer_rtc_interface_remove();
0937     return error;
0938 }
0939 device_initcall(alarmtimer_init);
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