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 = ktime_set(0, 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.tv64 || (delta.tv64 < min.tv64)) {
 258                         expires = next->expires;
 259                         min = delta;
 260                         type = i;
 261                 }
 262         }
 263         if (min.tv64 == 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, ktime_set(0, 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.tv64 || (delta.tv64 < freezer_delta.tv64)) {
 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.tv64 < 0)
 457                 return 0;
 458
 459         if (unlikely(delta.tv64 >= interval.tv64)) {
 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.tv64 > now.tv64)
 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 (posix_timer_event(ptr, 0) != 0)
 520                         ptr->it_overrun++;
 521         }
 522
 523         /* Re-add periodic timers */
 524         if (ptr->it.alarm.interval.tv64) {
 525                 ptr->it_overrun += alarm_forward(alarm, now,
 526                                                 ptr->it.alarm.interval);
 527                 result = ALARMTIMER_RESTART;
 528         }
 529         spin_unlock_irqrestore(&ptr->it_lock, flags);
 530
 531         return result;
 532 }
 533
 534 /**
 535  * alarm_clock_getres - posix getres interface
 536  * @which_clock: clockid
 537  * @tp: timespec to fill
 538  *
 539  * Returns the granularity of underlying alarm base clock
 540  */
 541 static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
 542 {
 543         if (!alarmtimer_get_rtcdev())
 544                 return -EINVAL;
 545
 546         tp->tv_sec = 0;
 547         tp->tv_nsec = hrtimer_resolution;
 548         return 0;
 549 }
 550
 551 /**
 552  * alarm_clock_get - posix clock_get interface
 553  * @which_clock: clockid
 554  * @tp: timespec to fill.
 555  *
 556  * Provides the underlying alarm base time.
 557  */
 558 static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
 559 {
 560         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 561
 562         if (!alarmtimer_get_rtcdev())
 563                 return -EINVAL;
 564
 565         *tp = ktime_to_timespec(base->gettime());
 566         return 0;
 567 }
 568
 569 /**
 570  * alarm_timer_create - posix timer_create interface
 571  * @new_timer: k_itimer pointer to manage
 572  *
 573  * Initializes the k_itimer structure.
 574  */
 575 static int alarm_timer_create(struct k_itimer *new_timer)
 576 {
 577         enum  alarmtimer_type type;
 578
 579         if (!alarmtimer_get_rtcdev())
 580                 return -ENOTSUPP;
 581
 582         if (!capable(CAP_WAKE_ALARM))
 583                 return -EPERM;
 584
 585         type = clock2alarm(new_timer->it_clock);
 586         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 587         return 0;
 588 }
 589
 590 /**
 591  * alarm_timer_get - posix timer_get interface
 592  * @new_timer: k_itimer pointer
 593  * @cur_setting: itimerspec data to fill
 594  *
 595  * Copies out the current itimerspec data
 596  */
 597 static void alarm_timer_get(struct k_itimer *timr,
 598                                 struct itimerspec *cur_setting)
 599 {
 600         ktime_t relative_expiry_time =
 601                 alarm_expires_remaining(&(timr->it.alarm.alarmtimer));
 602
 603         if (ktime_to_ns(relative_expiry_time) > 0) {
 604                 cur_setting->it_value = ktime_to_timespec(relative_expiry_time);
 605         } else {
 606                 cur_setting->it_value.tv_sec = 0;
 607                 cur_setting->it_value.tv_nsec = 0;
 608         }
 609
 610         cur_setting->it_interval = ktime_to_timespec(timr->it.alarm.interval);
 611 }
 612
 613 /**
 614  * alarm_timer_del - posix timer_del interface
 615  * @timr: k_itimer pointer to be deleted
 616  *
 617  * Cancels any programmed alarms for the given timer.
 618  */
 619 static int alarm_timer_del(struct k_itimer *timr)
 620 {
 621         if (!rtcdev)
 622                 return -ENOTSUPP;
 623
 624         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 625                 return TIMER_RETRY;
 626
 627         return 0;
 628 }
 629
 630 /**
 631  * alarm_timer_set - posix timer_set interface
 632  * @timr: k_itimer pointer to be deleted
 633  * @flags: timer flags
 634  * @new_setting: itimerspec to be used
 635  * @old_setting: itimerspec being replaced
 636  *
 637  * Sets the timer to new_setting, and starts the timer.
 638  */
 639 static int alarm_timer_set(struct k_itimer *timr, int flags,
 640                                 struct itimerspec *new_setting,
 641                                 struct itimerspec *old_setting)
 642 {
 643         ktime_t exp;
 644
 645         if (!rtcdev)
 646                 return -ENOTSUPP;
 647
 648         if (flags & ~TIMER_ABSTIME)
 649                 return -EINVAL;
 650
 651         if (old_setting)
 652                 alarm_timer_get(timr, old_setting);
 653
 654         /* If the timer was already set, cancel it */
 655         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 656                 return TIMER_RETRY;
 657
 658         /* start the timer */
 659         timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
 660         exp = timespec_to_ktime(new_setting->it_value);
 661         /* Convert (if necessary) to absolute time */
 662         if (flags != TIMER_ABSTIME) {
 663                 ktime_t now;
 664
 665                 now = alarm_bases[timr->it.alarm.alarmtimer.type].gettime();
 666                 exp = ktime_add(now, exp);
 667         }
 668
 669         alarm_start(&timr->it.alarm.alarmtimer, exp);
 670         return 0;
 671 }
 672
 673 /**
 674  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 675  * @alarm: ptr to alarm that fired
 676  *
 677  * Wakes up the task that set the alarmtimer
 678  */
 679 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 680                                                                 ktime_t now)
 681 {
 682         struct task_struct *task = (struct task_struct *)alarm->data;
 683
 684         alarm->data = NULL;
 685         if (task)
 686                 wake_up_process(task);
 687         return ALARMTIMER_NORESTART;
 688 }
 689
 690 /**
 691  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 692  * @alarm: ptr to alarmtimer
 693  * @absexp: absolute expiration time
 694  *
 695  * Sets the alarm timer and sleeps until it is fired or interrupted.
 696  */
 697 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
 698 {
 699         alarm->data = (void *)current;
 700         do {
 701                 set_current_state(TASK_INTERRUPTIBLE);
 702                 alarm_start(alarm, absexp);
 703                 if (likely(alarm->data))
 704                         schedule();
 705
 706                 alarm_cancel(alarm);
 707         } while (alarm->data && !signal_pending(current));
 708
 709         __set_current_state(TASK_RUNNING);
 710
 711         return (alarm->data == NULL);
 712 }
 713
 714
 715 /**
 716  * update_rmtp - Update remaining timespec value
 717  * @exp: expiration time
 718  * @type: timer type
 719  * @rmtp: user pointer to remaining timepsec value
 720  *
 721  * Helper function that fills in rmtp value with time between
 722  * now and the exp value
 723  */
 724 static int update_rmtp(ktime_t exp, enum  alarmtimer_type type,
 725                         struct timespec __user *rmtp)
 726 {
 727         struct timespec rmt;
 728         ktime_t rem;
 729
 730         rem = ktime_sub(exp, alarm_bases[type].gettime());
 731
 732         if (rem.tv64 <= 0)
 733                 return 0;
 734         rmt = ktime_to_timespec(rem);
 735
 736         if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
 737                 return -EFAULT;
 738
 739         return 1;
 740
 741 }
 742
 743 /**
 744  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 745  * @restart: ptr to restart block
 746  *
 747  * Handles restarted clock_nanosleep calls
 748  */
 749 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 750 {
 751         enum  alarmtimer_type type = restart->nanosleep.clockid;
 752         ktime_t exp;
 753         struct timespec __user  *rmtp;
 754         struct alarm alarm;
 755         int ret = 0;
 756
 757         exp.tv64 = restart->nanosleep.expires;
 758         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 759
 760         if (alarmtimer_do_nsleep(&alarm, exp))
 761                 goto out;
 762
 763         if (freezing(current))
 764                 alarmtimer_freezerset(exp, type);
 765
 766         rmtp = restart->nanosleep.rmtp;
 767         if (rmtp) {
 768                 ret = update_rmtp(exp, type, rmtp);
 769                 if (ret <= 0)
 770                         goto out;
 771         }
 772
 773
 774         /* The other values in restart are already filled in */
 775         ret = -ERESTART_RESTARTBLOCK;
 776 out:
 777         return ret;
 778 }
 779
 780 /**
 781  * alarm_timer_nsleep - alarmtimer nanosleep
 782  * @which_clock: clockid
 783  * @flags: determins abstime or relative
 784  * @tsreq: requested sleep time (abs or rel)
 785  * @rmtp: remaining sleep time saved
 786  *
 787  * Handles clock_nanosleep calls against _ALARM clockids
 788  */
 789 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 790                      struct timespec *tsreq, struct timespec __user *rmtp)
 791 {
 792         enum  alarmtimer_type type = clock2alarm(which_clock);
 793         struct alarm alarm;
 794         ktime_t exp;
 795         int ret = 0;
 796         struct restart_block *restart;
 797
 798         if (!alarmtimer_get_rtcdev())
 799                 return -ENOTSUPP;
 800
 801         if (flags & ~TIMER_ABSTIME)
 802                 return -EINVAL;
 803
 804         if (!capable(CAP_WAKE_ALARM))
 805                 return -EPERM;
 806
 807         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 808
 809         exp = timespec_to_ktime(*tsreq);
 810         /* Convert (if necessary) to absolute time */
 811         if (flags != TIMER_ABSTIME) {
 812                 ktime_t now = alarm_bases[type].gettime();
 813                 exp = ktime_add(now, exp);
 814         }
 815
 816         if (alarmtimer_do_nsleep(&alarm, exp))
 817                 goto out;
 818
 819         if (freezing(current))
 820                 alarmtimer_freezerset(exp, type);
 821
 822         /* abs timers don't set remaining time or restart */
 823         if (flags == TIMER_ABSTIME) {
 824                 ret = -ERESTARTNOHAND;
 825                 goto out;
 826         }
 827
 828         if (rmtp) {
 829                 ret = update_rmtp(exp, type, rmtp);
 830                 if (ret <= 0)
 831                         goto out;
 832         }
 833
 834         restart = &current->restart_block;
 835         restart->fn = alarm_timer_nsleep_restart;
 836         restart->nanosleep.clockid = type;
 837         restart->nanosleep.expires = exp.tv64;
 838         restart->nanosleep.rmtp = rmtp;
 839         ret = -ERESTART_RESTARTBLOCK;
 840
 841 out:
 842         return ret;
 843 }
 844
 845
 846 /* Suspend hook structures */
 847 static const struct dev_pm_ops alarmtimer_pm_ops = {
 848         .suspend = alarmtimer_suspend,
 849         .resume = alarmtimer_resume,
 850 };
 851
 852 static struct platform_driver alarmtimer_driver = {
 853         .driver = {
 854                 .name = "alarmtimer",
 855                 .pm = &alarmtimer_pm_ops,
 856         }
 857 };
 858
 859 /**
 860  * alarmtimer_init - Initialize alarm timer code
 861  *
 862  * This function initializes the alarm bases and registers
 863  * the posix clock ids.
 864  */
 865 static int __init alarmtimer_init(void)
 866 {
 867         struct platform_device *pdev;
 868         int error = 0;
 869         int i;
 870         struct k_clock alarm_clock = {
 871                 .clock_getres   = alarm_clock_getres,
 872                 .clock_get      = alarm_clock_get,
 873                 .timer_create   = alarm_timer_create,
 874                 .timer_set      = alarm_timer_set,
 875                 .timer_del      = alarm_timer_del,
 876                 .timer_get      = alarm_timer_get,
 877                 .nsleep         = alarm_timer_nsleep,
 878         };
 879
 880         alarmtimer_rtc_timer_init();
 881
 882         if (IS_ENABLED(CONFIG_POSIX_TIMERS)) {
 883                 posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
 884                 posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
 885         }
 886
 887         /* Initialize alarm bases */
 888         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 889         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
 890         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 891         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
 892         for (i = 0; i < ALARM_NUMTYPE; i++) {
 893                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 894                 spin_lock_init(&alarm_bases[i].lock);
 895         }
 896
 897         error = alarmtimer_rtc_interface_setup();
 898         if (error)
 899                 return error;
 900
 901         error = platform_driver_register(&alarmtimer_driver);
 902         if (error)
 903                 goto out_if;
 904
 905         pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
 906         if (IS_ERR(pdev)) {
 907                 error = PTR_ERR(pdev);
 908                 goto out_drv;
 909         }
 910         ws = wakeup_source_register("alarmtimer");
 911         return 0;
 912
 913 out_drv:
 914         platform_driver_unregister(&alarmtimer_driver);
 915 out_if:
 916         alarmtimer_rtc_interface_remove();
 917         return error;
 918 }
 919 device_initcall(alarmtimer_init);