kernel/time/alarmtimer.c

   1 /*
   2  * Alarmtimer interface
   3  *
   4  * This interface provides a timer which is similarto hrtimers,
   5  * but triggers a RTC alarm if the box is suspend.
   6  *
   7  * This interface is influenced by the Android RTC Alarm timer
   8  * interface.
   9  *
  10  * Copyright (C) 2010 IBM Corperation
  11  *
  12  * Author: John Stultz <john.stultz@linaro.org>
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License version 2 as
  16  * published by the Free Software Foundation.
  17  */
  18 #include <linux/time.h>
  19 #include <linux/hrtimer.h>
  20 #include <linux/timerqueue.h>
  21 #include <linux/rtc.h>
  22 #include <linux/alarmtimer.h>
  23 #include <linux/mutex.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/posix-timers.h>
  26 #include <linux/workqueue.h>
  27 #include <linux/freezer.h>
  28
  29 #define CREATE_TRACE_POINTS
  30 #include <trace/events/alarmtimer.h>
  31
  32 /**
  33  * struct alarm_base - Alarm timer bases
  34  * @lock:               Lock for syncrhonized access to the base
  35  * @timerqueue:         Timerqueue head managing the list of events
  36  * @gettime:            Function to read the time correlating to the base
  37  * @base_clockid:       clockid for the base
  38  */
  39 static struct alarm_base {
  40         spinlock_t              lock;
  41         struct timerqueue_head  timerqueue;
  42         ktime_t                 (*gettime)(void);
  43         clockid_t               base_clockid;
  44 } alarm_bases[ALARM_NUMTYPE];
  45
  46 /* freezer information to handle clock_nanosleep triggered wakeups */
  47 static enum alarmtimer_type freezer_alarmtype;
  48 static ktime_t freezer_expires;
  49 static ktime_t freezer_delta;
  50 static DEFINE_SPINLOCK(freezer_delta_lock);
  51
  52 static struct wakeup_source *ws;
  53
  54 #ifdef CONFIG_RTC_CLASS
  55 /* rtc timer and device for setting alarm wakeups at suspend */
  56 static struct rtc_timer         rtctimer;
  57 static struct rtc_device        *rtcdev;
  58 static DEFINE_SPINLOCK(rtcdev_lock);
  59
  60 /**
  61  * alarmtimer_get_rtcdev - Return selected rtcdevice
  62  *
  63  * This function returns the rtc device to use for wakealarms.
  64  * If one has not already been chosen, it checks to see if a
  65  * functional rtc device is available.
  66  */
  67 struct rtc_device *alarmtimer_get_rtcdev(void)
  68 {
  69         unsigned long flags;
  70         struct rtc_device *ret;
  71
  72         spin_lock_irqsave(&rtcdev_lock, flags);
  73         ret = rtcdev;
  74         spin_unlock_irqrestore(&rtcdev_lock, flags);
  75
  76         return ret;
  77 }
  78 EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
  79
  80 static int alarmtimer_rtc_add_device(struct device *dev,
  81                                 struct class_interface *class_intf)
  82 {
  83         unsigned long flags;
  84         struct rtc_device *rtc = to_rtc_device(dev);
  85
  86         if (rtcdev)
  87                 return -EBUSY;
  88
  89         if (!rtc->ops->set_alarm)
  90                 return -1;
  91         if (!device_may_wakeup(rtc->dev.parent))
  92                 return -1;
  93
  94         spin_lock_irqsave(&rtcdev_lock, flags);
  95         if (!rtcdev) {
  96                 rtcdev = rtc;
  97                 /* hold a reference so it doesn't go away */
  98                 get_device(dev);
  99         }
 100         spin_unlock_irqrestore(&rtcdev_lock, flags);
 101         return 0;
 102 }
 103
 104 static inline void alarmtimer_rtc_timer_init(void)
 105 {
 106         rtc_timer_init(&rtctimer, NULL, NULL);
 107 }
 108
 109 static struct class_interface alarmtimer_rtc_interface = {
 110         .add_dev = &alarmtimer_rtc_add_device,
 111 };
 112
 113 static int alarmtimer_rtc_interface_setup(void)
 114 {
 115         alarmtimer_rtc_interface.class = rtc_class;
 116         return class_interface_register(&alarmtimer_rtc_interface);
 117 }
 118 static void alarmtimer_rtc_interface_remove(void)
 119 {
 120         class_interface_unregister(&alarmtimer_rtc_interface);
 121 }
 122 #else
 123 struct rtc_device *alarmtimer_get_rtcdev(void)
 124 {
 125         return NULL;
 126 }
 127 #define rtcdev (NULL)
 128 static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
 129 static inline void alarmtimer_rtc_interface_remove(void) { }
 130 static inline void alarmtimer_rtc_timer_init(void) { }
 131 #endif
 132
 133 /**
 134  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
 135  * @base: pointer to the base where the timer is being run
 136  * @alarm: pointer to alarm being enqueued.
 137  *
 138  * Adds alarm to a alarm_base timerqueue
 139  *
 140  * Must hold base->lock when calling.
 141  */
 142 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
 143 {
 144         if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
 145                 timerqueue_del(&base->timerqueue, &alarm->node);
 146
 147         timerqueue_add(&base->timerqueue, &alarm->node);
 148         alarm->state |= ALARMTIMER_STATE_ENQUEUED;
 149 }
 150
 151 /**
 152  * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
 153  * @base: pointer to the base where the timer is running
 154  * @alarm: pointer to alarm being removed
 155  *
 156  * Removes alarm to a alarm_base timerqueue
 157  *
 158  * Must hold base->lock when calling.
 159  */
 160 static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
 161 {
 162         if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
 163                 return;
 164
 165         timerqueue_del(&base->timerqueue, &alarm->node);
 166         alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
 167 }
 168
 169
 170 /**
 171  * alarmtimer_fired - Handles alarm hrtimer being fired.
 172  * @timer: pointer to hrtimer being run
 173  *
 174  * When a alarm timer fires, this runs through the timerqueue to
 175  * see which alarms expired, and runs those. If there are more alarm
 176  * timers queued for the future, we set the hrtimer to fire when
 177  * when the next future alarm timer expires.
 178  */
 179 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 180 {
 181         struct alarm *alarm = container_of(timer, struct alarm, timer);
 182         struct alarm_base *base = &alarm_bases[alarm->type];
 183         unsigned long flags;
 184         int ret = HRTIMER_NORESTART;
 185         int restart = ALARMTIMER_NORESTART;
 186
 187         spin_lock_irqsave(&base->lock, flags);
 188         alarmtimer_dequeue(base, alarm);
 189         spin_unlock_irqrestore(&base->lock, flags);
 190
 191         if (alarm->function)
 192                 restart = alarm->function(alarm, base->gettime());
 193
 194         spin_lock_irqsave(&base->lock, flags);
 195         if (restart != ALARMTIMER_NORESTART) {
 196                 hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 197                 alarmtimer_enqueue(base, alarm);
 198                 ret = HRTIMER_RESTART;
 199         }
 200         spin_unlock_irqrestore(&base->lock, flags);
 201
 202         trace_alarmtimer_fired(alarm, base->gettime());
 203         return ret;
 204
 205 }
 206
 207 ktime_t alarm_expires_remaining(const struct alarm *alarm)
 208 {
 209         struct alarm_base *base = &alarm_bases[alarm->type];
 210         return ktime_sub(alarm->node.expires, base->gettime());
 211 }
 212 EXPORT_SYMBOL_GPL(alarm_expires_remaining);
 213
 214 #ifdef CONFIG_RTC_CLASS
 215 /**
 216  * alarmtimer_suspend - Suspend time callback
 217  * @dev: unused
 218  * @state: unused
 219  *
 220  * When we are going into suspend, we look through the bases
 221  * to see which is the soonest timer to expire. We then
 222  * set an rtc timer to fire that far into the future, which
 223  * will wake us from suspend.
 224  */
 225 static int alarmtimer_suspend(struct device *dev)
 226 {
 227         ktime_t min, now, expires;
 228         int i, ret, type;
 229         struct rtc_device *rtc;
 230         unsigned long flags;
 231         struct rtc_time tm;
 232
 233         spin_lock_irqsave(&freezer_delta_lock, flags);
 234         min = freezer_delta;
 235         expires = freezer_expires;
 236         type = freezer_alarmtype;
 237         freezer_delta = 0;
 238         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 239
 240         rtc = alarmtimer_get_rtcdev();
 241         /* If we have no rtcdev, just return */
 242         if (!rtc)
 243                 return 0;
 244
 245         /* Find the soonest timer to expire*/
 246         for (i = 0; i < ALARM_NUMTYPE; i++) {
 247                 struct alarm_base *base = &alarm_bases[i];
 248                 struct timerqueue_node *next;
 249                 ktime_t delta;
 250
 251                 spin_lock_irqsave(&base->lock, flags);
 252                 next = timerqueue_getnext(&base->timerqueue);
 253                 spin_unlock_irqrestore(&base->lock, flags);
 254                 if (!next)
 255                         continue;
 256                 delta = ktime_sub(next->expires, base->gettime());
 257                 if (!min || (delta < min)) {
 258                         expires = next->expires;
 259                         min = delta;
 260                         type = i;
 261                 }
 262         }
 263         if (min == 0)
 264                 return 0;
 265
 266         if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
 267                 __pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
 268                 return -EBUSY;
 269         }
 270
 271         trace_alarmtimer_suspend(expires, type);
 272
 273         /* Setup an rtc timer to fire that far in the future */
 274         rtc_timer_cancel(rtc, &rtctimer);
 275         rtc_read_time(rtc, &tm);
 276         now = rtc_tm_to_ktime(tm);
 277         now = ktime_add(now, min);
 278
 279         /* Set alarm, if in the past reject suspend briefly to handle */
 280         ret = rtc_timer_start(rtc, &rtctimer, now, 0);
 281         if (ret < 0)
 282                 __pm_wakeup_event(ws, MSEC_PER_SEC);
 283         return ret;
 284 }
 285
 286 static int alarmtimer_resume(struct device *dev)
 287 {
 288         struct rtc_device *rtc;
 289
 290         rtc = alarmtimer_get_rtcdev();
 291         if (rtc)
 292                 rtc_timer_cancel(rtc, &rtctimer);
 293         return 0;
 294 }
 295
 296 #else
 297 static int alarmtimer_suspend(struct device *dev)
 298 {
 299         return 0;
 300 }
 301
 302 static int alarmtimer_resume(struct device *dev)
 303 {
 304         return 0;
 305 }
 306 #endif
 307
 308 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 309 {
 310         struct alarm_base *base;
 311         unsigned long flags;
 312         ktime_t delta;
 313
 314         switch(type) {
 315         case ALARM_REALTIME:
 316                 base = &alarm_bases[ALARM_REALTIME];
 317                 type = ALARM_REALTIME_FREEZER;
 318                 break;
 319         case ALARM_BOOTTIME:
 320                 base = &alarm_bases[ALARM_BOOTTIME];
 321                 type = ALARM_BOOTTIME_FREEZER;
 322                 break;
 323         default:
 324                 WARN_ONCE(1, "Invalid alarm type: %d\n", type);
 325                 return;
 326         }
 327
 328         delta = ktime_sub(absexp, base->gettime());
 329
 330         spin_lock_irqsave(&freezer_delta_lock, flags);
 331         if (!freezer_delta || (delta < freezer_delta)) {
 332                 freezer_delta = delta;
 333                 freezer_expires = absexp;
 334                 freezer_alarmtype = type;
 335         }
 336         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 337 }
 338
 339
 340 /**
 341  * alarm_init - Initialize an alarm structure
 342  * @alarm: ptr to alarm to be initialized
 343  * @type: the type of the alarm
 344  * @function: callback that is run when the alarm fires
 345  */
 346 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 347                 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 348 {
 349         timerqueue_init(&alarm->node);
 350         hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
 351                         HRTIMER_MODE_ABS);
 352         alarm->timer.function = alarmtimer_fired;
 353         alarm->function = function;
 354         alarm->type = type;
 355         alarm->state = ALARMTIMER_STATE_INACTIVE;
 356 }
 357 EXPORT_SYMBOL_GPL(alarm_init);
 358
 359 /**
 360  * alarm_start - Sets an absolute alarm to fire
 361  * @alarm: ptr to alarm to set
 362  * @start: time to run the alarm
 363  */
 364 void alarm_start(struct alarm *alarm, ktime_t start)
 365 {
 366         struct alarm_base *base = &alarm_bases[alarm->type];
 367         unsigned long flags;
 368
 369         spin_lock_irqsave(&base->lock, flags);
 370         alarm->node.expires = start;
 371         alarmtimer_enqueue(base, alarm);
 372         hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
 373         spin_unlock_irqrestore(&base->lock, flags);
 374
 375         trace_alarmtimer_start(alarm, base->gettime());
 376 }
 377 EXPORT_SYMBOL_GPL(alarm_start);
 378
 379 /**
 380  * alarm_start_relative - Sets a relative alarm to fire
 381  * @alarm: ptr to alarm to set
 382  * @start: time relative to now to run the alarm
 383  */
 384 void alarm_start_relative(struct alarm *alarm, ktime_t start)
 385 {
 386         struct alarm_base *base = &alarm_bases[alarm->type];
 387
 388         start = ktime_add(start, base->gettime());
 389         alarm_start(alarm, start);
 390 }
 391 EXPORT_SYMBOL_GPL(alarm_start_relative);
 392
 393 void alarm_restart(struct alarm *alarm)
 394 {
 395         struct alarm_base *base = &alarm_bases[alarm->type];
 396         unsigned long flags;
 397
 398         spin_lock_irqsave(&base->lock, flags);
 399         hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 400         hrtimer_restart(&alarm->timer);
 401         alarmtimer_enqueue(base, alarm);
 402         spin_unlock_irqrestore(&base->lock, flags);
 403 }
 404 EXPORT_SYMBOL_GPL(alarm_restart);
 405
 406 /**
 407  * alarm_try_to_cancel - Tries to cancel an alarm timer
 408  * @alarm: ptr to alarm to be canceled
 409  *
 410  * Returns 1 if the timer was canceled, 0 if it was not running,
 411  * and -1 if the callback was running
 412  */
 413 int alarm_try_to_cancel(struct alarm *alarm)
 414 {
 415         struct alarm_base *base = &alarm_bases[alarm->type];
 416         unsigned long flags;
 417         int ret;
 418
 419         spin_lock_irqsave(&base->lock, flags);
 420         ret = hrtimer_try_to_cancel(&alarm->timer);
 421         if (ret >= 0)
 422                 alarmtimer_dequeue(base, alarm);
 423         spin_unlock_irqrestore(&base->lock, flags);
 424
 425         trace_alarmtimer_cancel(alarm, base->gettime());
 426         return ret;
 427 }
 428 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
 429
 430
 431 /**
 432  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
 433  * @alarm: ptr to alarm to be canceled
 434  *
 435  * Returns 1 if the timer was canceled, 0 if it was not active.
 436  */
 437 int alarm_cancel(struct alarm *alarm)
 438 {
 439         for (;;) {
 440                 int ret = alarm_try_to_cancel(alarm);
 441                 if (ret >= 0)
 442                         return ret;
 443                 cpu_relax();
 444         }
 445 }
 446 EXPORT_SYMBOL_GPL(alarm_cancel);
 447
 448
 449 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
 450 {
 451         u64 overrun = 1;
 452         ktime_t delta;
 453
 454         delta = ktime_sub(now, alarm->node.expires);
 455
 456         if (delta < 0)
 457                 return 0;
 458
 459         if (unlikely(delta >= interval)) {
 460                 s64 incr = ktime_to_ns(interval);
 461
 462                 overrun = ktime_divns(delta, incr);
 463
 464                 alarm->node.expires = ktime_add_ns(alarm->node.expires,
 465                                                         incr*overrun);
 466
 467                 if (alarm->node.expires > now)
 468                         return overrun;
 469                 /*
 470                  * This (and the ktime_add() below) is the
 471                  * correction for exact:
 472                  */
 473                 overrun++;
 474         }
 475
 476         alarm->node.expires = ktime_add(alarm->node.expires, interval);
 477         return overrun;
 478 }
 479 EXPORT_SYMBOL_GPL(alarm_forward);
 480
 481 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 482 {
 483         struct alarm_base *base = &alarm_bases[alarm->type];
 484
 485         return alarm_forward(alarm, base->gettime(), interval);
 486 }
 487 EXPORT_SYMBOL_GPL(alarm_forward_now);
 488
 489
 490 /**
 491  * clock2alarm - helper that converts from clockid to alarmtypes
 492  * @clockid: clockid.
 493  */
 494 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 495 {
 496         if (clockid == CLOCK_REALTIME_ALARM)
 497                 return ALARM_REALTIME;
 498         if (clockid == CLOCK_BOOTTIME_ALARM)
 499                 return ALARM_BOOTTIME;
 500         return -1;
 501 }
 502
 503 /**
 504  * alarm_handle_timer - Callback for posix timers
 505  * @alarm: alarm that fired
 506  *
 507  * Posix timer callback for expired alarm timers.
 508  */
 509 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 510                                                         ktime_t now)
 511 {
 512         unsigned long flags;
 513         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 514                                                 it.alarm.alarmtimer);
 515         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
 516
 517         spin_lock_irqsave(&ptr->it_lock, flags);
 518         if ((ptr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) {
 519                 if (IS_ENABLED(CONFIG_POSIX_TIMERS) &&
 520                     posix_timer_event(ptr, 0) != 0)
 521                         ptr->it_overrun++;
 522         }
 523
 524         /* Re-add periodic timers */
 525         if (ptr->it.alarm.interval) {
 526                 ptr->it_overrun += alarm_forward(alarm, now,
 527                                                 ptr->it.alarm.interval);
 528                 result = ALARMTIMER_RESTART;
 529         }
 530         spin_unlock_irqrestore(&ptr->it_lock, flags);
 531
 532         return result;
 533 }
 534
 535 /**
 536  * alarm_clock_getres - posix getres interface
 537  * @which_clock: clockid
 538  * @tp: timespec to fill
 539  *
 540  * Returns the granularity of underlying alarm base clock
 541  */
 542 static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
 543 {
 544         if (!alarmtimer_get_rtcdev())
 545                 return -EINVAL;
 546
 547         tp->tv_sec = 0;
 548         tp->tv_nsec = hrtimer_resolution;
 549         return 0;
 550 }
 551
 552 /**
 553  * alarm_clock_get - posix clock_get interface
 554  * @which_clock: clockid
 555  * @tp: timespec to fill.
 556  *
 557  * Provides the underlying alarm base time.
 558  */
 559 static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
 560 {
 561         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 562
 563         if (!alarmtimer_get_rtcdev())
 564                 return -EINVAL;
 565
 566         *tp = ktime_to_timespec(base->gettime());
 567         return 0;
 568 }
 569
 570 /**
 571  * alarm_timer_create - posix timer_create interface
 572  * @new_timer: k_itimer pointer to manage
 573  *
 574  * Initializes the k_itimer structure.
 575  */
 576 static int alarm_timer_create(struct k_itimer *new_timer)
 577 {
 578         enum  alarmtimer_type type;
 579
 580         if (!alarmtimer_get_rtcdev())
 581                 return -ENOTSUPP;
 582
 583         if (!capable(CAP_WAKE_ALARM))
 584                 return -EPERM;
 585
 586         type = clock2alarm(new_timer->it_clock);
 587         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 588         return 0;
 589 }
 590
 591 /**
 592  * alarm_timer_get - posix timer_get interface
 593  * @new_timer: k_itimer pointer
 594  * @cur_setting: itimerspec data to fill
 595  *
 596  * Copies out the current itimerspec data
 597  */
 598 static void alarm_timer_get(struct k_itimer *timr,
 599                                 struct itimerspec *cur_setting)
 600 {
 601         ktime_t relative_expiry_time =
 602                 alarm_expires_remaining(&(timr->it.alarm.alarmtimer));
 603
 604         if (ktime_to_ns(relative_expiry_time) > 0) {
 605                 cur_setting->it_value = ktime_to_timespec(relative_expiry_time);
 606         } else {
 607                 cur_setting->it_value.tv_sec = 0;
 608                 cur_setting->it_value.tv_nsec = 0;
 609         }
 610
 611         cur_setting->it_interval = ktime_to_timespec(timr->it.alarm.interval);
 612 }
 613
 614 /**
 615  * alarm_timer_del - posix timer_del interface
 616  * @timr: k_itimer pointer to be deleted
 617  *
 618  * Cancels any programmed alarms for the given timer.
 619  */
 620 static int alarm_timer_del(struct k_itimer *timr)
 621 {
 622         if (!rtcdev)
 623                 return -ENOTSUPP;
 624
 625         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 626                 return TIMER_RETRY;
 627
 628         return 0;
 629 }
 630
 631 /**
 632  * alarm_timer_set - posix timer_set interface
 633  * @timr: k_itimer pointer to be deleted
 634  * @flags: timer flags
 635  * @new_setting: itimerspec to be used
 636  * @old_setting: itimerspec being replaced
 637  *
 638  * Sets the timer to new_setting, and starts the timer.
 639  */
 640 static int alarm_timer_set(struct k_itimer *timr, int flags,
 641                                 struct itimerspec *new_setting,
 642                                 struct itimerspec *old_setting)
 643 {
 644         ktime_t exp;
 645
 646         if (!rtcdev)
 647                 return -ENOTSUPP;
 648
 649         if (flags & ~TIMER_ABSTIME)
 650                 return -EINVAL;
 651
 652         if (old_setting)
 653                 alarm_timer_get(timr, old_setting);
 654
 655         /* If the timer was already set, cancel it */
 656         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 657                 return TIMER_RETRY;
 658
 659         /* start the timer */
 660         timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
 661         exp = timespec_to_ktime(new_setting->it_value);
 662         /* Convert (if necessary) to absolute time */
 663         if (flags != TIMER_ABSTIME) {
 664                 ktime_t now;
 665
 666                 now = alarm_bases[timr->it.alarm.alarmtimer.type].gettime();
 667                 exp = ktime_add(now, exp);
 668         }
 669
 670         alarm_start(&timr->it.alarm.alarmtimer, exp);
 671         return 0;
 672 }
 673
 674 /**
 675  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 676  * @alarm: ptr to alarm that fired
 677  *
 678  * Wakes up the task that set the alarmtimer
 679  */
 680 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 681                                                                 ktime_t now)
 682 {
 683         struct task_struct *task = (struct task_struct *)alarm->data;
 684
 685         alarm->data = NULL;
 686         if (task)
 687                 wake_up_process(task);
 688         return ALARMTIMER_NORESTART;
 689 }
 690
 691 /**
 692  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 693  * @alarm: ptr to alarmtimer
 694  * @absexp: absolute expiration time
 695  *
 696  * Sets the alarm timer and sleeps until it is fired or interrupted.
 697  */
 698 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
 699 {
 700         alarm->data = (void *)current;
 701         do {
 702                 set_current_state(TASK_INTERRUPTIBLE);
 703                 alarm_start(alarm, absexp);
 704                 if (likely(alarm->data))
 705                         schedule();
 706
 707                 alarm_cancel(alarm);
 708         } while (alarm->data && !signal_pending(current));
 709
 710         __set_current_state(TASK_RUNNING);
 711
 712         return (alarm->data == NULL);
 713 }
 714
 715
 716 /**
 717  * update_rmtp - Update remaining timespec value
 718  * @exp: expiration time
 719  * @type: timer type
 720  * @rmtp: user pointer to remaining timepsec value
 721  *
 722  * Helper function that fills in rmtp value with time between
 723  * now and the exp value
 724  */
 725 static int update_rmtp(ktime_t exp, enum  alarmtimer_type type,
 726                         struct timespec __user *rmtp)
 727 {
 728         struct timespec rmt;
 729         ktime_t rem;
 730
 731         rem = ktime_sub(exp, alarm_bases[type].gettime());
 732
 733         if (rem <= 0)
 734                 return 0;
 735         rmt = ktime_to_timespec(rem);
 736
 737         if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
 738                 return -EFAULT;
 739
 740         return 1;
 741
 742 }
 743
 744 /**
 745  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 746  * @restart: ptr to restart block
 747  *
 748  * Handles restarted clock_nanosleep calls
 749  */
 750 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 751 {
 752         enum  alarmtimer_type type = restart->nanosleep.clockid;
 753         ktime_t exp;
 754         struct timespec __user  *rmtp;
 755         struct alarm alarm;
 756         int ret = 0;
 757
 758         exp = restart->nanosleep.expires;
 759         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 760
 761         if (alarmtimer_do_nsleep(&alarm, exp))
 762                 goto out;
 763
 764         if (freezing(current))
 765                 alarmtimer_freezerset(exp, type);
 766
 767         rmtp = restart->nanosleep.rmtp;
 768         if (rmtp) {
 769                 ret = update_rmtp(exp, type, rmtp);
 770                 if (ret <= 0)
 771                         goto out;
 772         }
 773
 774
 775         /* The other values in restart are already filled in */
 776         ret = -ERESTART_RESTARTBLOCK;
 777 out:
 778         return ret;
 779 }
 780
 781 /**
 782  * alarm_timer_nsleep - alarmtimer nanosleep
 783  * @which_clock: clockid
 784  * @flags: determins abstime or relative
 785  * @tsreq: requested sleep time (abs or rel)
 786  * @rmtp: remaining sleep time saved
 787  *
 788  * Handles clock_nanosleep calls against _ALARM clockids
 789  */
 790 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 791                      struct timespec *tsreq, struct timespec __user *rmtp)
 792 {
 793         enum  alarmtimer_type type = clock2alarm(which_clock);
 794         struct alarm alarm;
 795         ktime_t exp;
 796         int ret = 0;
 797         struct restart_block *restart;
 798
 799         if (!alarmtimer_get_rtcdev())
 800                 return -ENOTSUPP;
 801
 802         if (flags & ~TIMER_ABSTIME)
 803                 return -EINVAL;
 804
 805         if (!capable(CAP_WAKE_ALARM))
 806                 return -EPERM;
 807
 808         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 809
 810         exp = timespec_to_ktime(*tsreq);
 811         /* Convert (if necessary) to absolute time */
 812         if (flags != TIMER_ABSTIME) {
 813                 ktime_t now = alarm_bases[type].gettime();
 814                 exp = ktime_add(now, exp);
 815         }
 816
 817         if (alarmtimer_do_nsleep(&alarm, exp))
 818                 goto out;
 819
 820         if (freezing(current))
 821                 alarmtimer_freezerset(exp, type);
 822
 823         /* abs timers don't set remaining time or restart */
 824         if (flags == TIMER_ABSTIME) {
 825                 ret = -ERESTARTNOHAND;
 826                 goto out;
 827         }
 828
 829         if (rmtp) {
 830                 ret = update_rmtp(exp, type, rmtp);
 831                 if (ret <= 0)
 832                         goto out;
 833         }
 834
 835         restart = &current->restart_block;
 836         restart->fn = alarm_timer_nsleep_restart;
 837         restart->nanosleep.clockid = type;
 838         restart->nanosleep.expires = exp;
 839         restart->nanosleep.rmtp = rmtp;
 840         ret = -ERESTART_RESTARTBLOCK;
 841
 842 out:
 843         return ret;
 844 }
 845
 846
 847 /* Suspend hook structures */
 848 static const struct dev_pm_ops alarmtimer_pm_ops = {
 849         .suspend = alarmtimer_suspend,
 850         .resume = alarmtimer_resume,
 851 };
 852
 853 static struct platform_driver alarmtimer_driver = {
 854         .driver = {
 855                 .name = "alarmtimer",
 856                 .pm = &alarmtimer_pm_ops,
 857         }
 858 };
 859
 860 /**
 861  * alarmtimer_init - Initialize alarm timer code
 862  *
 863  * This function initializes the alarm bases and registers
 864  * the posix clock ids.
 865  */
 866 static int __init alarmtimer_init(void)
 867 {
 868         struct platform_device *pdev;
 869         int error = 0;
 870         int i;
 871         struct k_clock alarm_clock = {
 872                 .clock_getres   = alarm_clock_getres,
 873                 .clock_get      = alarm_clock_get,
 874                 .timer_create   = alarm_timer_create,
 875                 .timer_set      = alarm_timer_set,
 876                 .timer_del      = alarm_timer_del,
 877                 .timer_get      = alarm_timer_get,
 878                 .nsleep         = alarm_timer_nsleep,
 879         };
 880
 881         alarmtimer_rtc_timer_init();
 882
 883         if (IS_ENABLED(CONFIG_POSIX_TIMERS)) {
 884                 posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
 885                 posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
 886         }
 887
 888         /* Initialize alarm bases */
 889         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 890         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
 891         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 892         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
 893         for (i = 0; i < ALARM_NUMTYPE; i++) {
 894                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 895                 spin_lock_init(&alarm_bases[i].lock);
 896         }
 897
 898         error = alarmtimer_rtc_interface_setup();
 899         if (error)
 900                 return error;
 901
 902         error = platform_driver_register(&alarmtimer_driver);
 903         if (error)
 904                 goto out_if;
 905
 906         pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
 907         if (IS_ERR(pdev)) {
 908                 error = PTR_ERR(pdev);
 909                 goto out_drv;
 910         }
 911         ws = wakeup_source_register("alarmtimer");
 912         return 0;
 913
 914 out_drv:
 915         platform_driver_unregister(&alarmtimer_driver);
 916 out_if:
 917         alarmtimer_rtc_interface_remove();
 918         return error;
 919 }
 920 device_initcall(alarmtimer_init);