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 /**
  30  * struct alarm_base - Alarm timer bases
  31  * @lock:               Lock for syncrhonized access to the base
  32  * @timerqueue:         Timerqueue head managing the list of events
  33  * @timer:              hrtimer used to schedule events while running
  34  * @gettime:            Function to read the time correlating to the base
  35  * @base_clockid:       clockid for the base
  36  */
  37 static struct alarm_base {
  38         spinlock_t              lock;
  39         struct timerqueue_head  timerqueue;
  40         ktime_t                 (*gettime)(void);
  41         clockid_t               base_clockid;
  42 } alarm_bases[ALARM_NUMTYPE];
  43
  44 /* freezer delta & lock used to handle clock_nanosleep triggered wakeups */
  45 static ktime_t freezer_delta;
  46 static DEFINE_SPINLOCK(freezer_delta_lock);
  47
  48 static struct wakeup_source *ws;
  49
  50 #ifdef CONFIG_RTC_CLASS
  51 /* rtc timer and device for setting alarm wakeups at suspend */
  52 static struct rtc_timer         rtctimer;
  53 static struct rtc_device        *rtcdev;
  54 static DEFINE_SPINLOCK(rtcdev_lock);
  55
  56 /**
  57  * alarmtimer_get_rtcdev - Return selected rtcdevice
  58  *
  59  * This function returns the rtc device to use for wakealarms.
  60  * If one has not already been chosen, it checks to see if a
  61  * functional rtc device is available.
  62  */
  63 struct rtc_device *alarmtimer_get_rtcdev(void)
  64 {
  65         unsigned long flags;
  66         struct rtc_device *ret;
  67
  68         spin_lock_irqsave(&rtcdev_lock, flags);
  69         ret = rtcdev;
  70         spin_unlock_irqrestore(&rtcdev_lock, flags);
  71
  72         return ret;
  73 }
  74 EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
  75
  76 static int alarmtimer_rtc_add_device(struct device *dev,
  77                                 struct class_interface *class_intf)
  78 {
  79         unsigned long flags;
  80         struct rtc_device *rtc = to_rtc_device(dev);
  81
  82         if (rtcdev)
  83                 return -EBUSY;
  84
  85         if (!rtc->ops->set_alarm)
  86                 return -1;
  87         if (!device_may_wakeup(rtc->dev.parent))
  88                 return -1;
  89
  90         spin_lock_irqsave(&rtcdev_lock, flags);
  91         if (!rtcdev) {
  92                 rtcdev = rtc;
  93                 /* hold a reference so it doesn't go away */
  94                 get_device(dev);
  95         }
  96         spin_unlock_irqrestore(&rtcdev_lock, flags);
  97         return 0;
  98 }
  99
 100 static inline void alarmtimer_rtc_timer_init(void)
 101 {
 102         rtc_timer_init(&rtctimer, NULL, NULL);
 103 }
 104
 105 static struct class_interface alarmtimer_rtc_interface = {
 106         .add_dev = &alarmtimer_rtc_add_device,
 107 };
 108
 109 static int alarmtimer_rtc_interface_setup(void)
 110 {
 111         alarmtimer_rtc_interface.class = rtc_class;
 112         return class_interface_register(&alarmtimer_rtc_interface);
 113 }
 114 static void alarmtimer_rtc_interface_remove(void)
 115 {
 116         class_interface_unregister(&alarmtimer_rtc_interface);
 117 }
 118 #else
 119 struct rtc_device *alarmtimer_get_rtcdev(void)
 120 {
 121         return NULL;
 122 }
 123 #define rtcdev (NULL)
 124 static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
 125 static inline void alarmtimer_rtc_interface_remove(void) { }
 126 static inline void alarmtimer_rtc_timer_init(void) { }
 127 #endif
 128
 129 /**
 130  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
 131  * @base: pointer to the base where the timer is being run
 132  * @alarm: pointer to alarm being enqueued.
 133  *
 134  * Adds alarm to a alarm_base timerqueue
 135  *
 136  * Must hold base->lock when calling.
 137  */
 138 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
 139 {
 140         if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
 141                 timerqueue_del(&base->timerqueue, &alarm->node);
 142
 143         timerqueue_add(&base->timerqueue, &alarm->node);
 144         alarm->state |= ALARMTIMER_STATE_ENQUEUED;
 145 }
 146
 147 /**
 148  * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
 149  * @base: pointer to the base where the timer is running
 150  * @alarm: pointer to alarm being removed
 151  *
 152  * Removes alarm to a alarm_base timerqueue
 153  *
 154  * Must hold base->lock when calling.
 155  */
 156 static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
 157 {
 158         if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
 159                 return;
 160
 161         timerqueue_del(&base->timerqueue, &alarm->node);
 162         alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
 163 }
 164
 165
 166 /**
 167  * alarmtimer_fired - Handles alarm hrtimer being fired.
 168  * @timer: pointer to hrtimer being run
 169  *
 170  * When a alarm timer fires, this runs through the timerqueue to
 171  * see which alarms expired, and runs those. If there are more alarm
 172  * timers queued for the future, we set the hrtimer to fire when
 173  * when the next future alarm timer expires.
 174  */
 175 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 176 {
 177         struct alarm *alarm = container_of(timer, struct alarm, timer);
 178         struct alarm_base *base = &alarm_bases[alarm->type];
 179         unsigned long flags;
 180         int ret = HRTIMER_NORESTART;
 181         int restart = ALARMTIMER_NORESTART;
 182
 183         spin_lock_irqsave(&base->lock, flags);
 184         alarmtimer_dequeue(base, alarm);
 185         spin_unlock_irqrestore(&base->lock, flags);
 186
 187         if (alarm->function)
 188                 restart = alarm->function(alarm, base->gettime());
 189
 190         spin_lock_irqsave(&base->lock, flags);
 191         if (restart != ALARMTIMER_NORESTART) {
 192                 hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 193                 alarmtimer_enqueue(base, alarm);
 194                 ret = HRTIMER_RESTART;
 195         }
 196         spin_unlock_irqrestore(&base->lock, flags);
 197
 198         return ret;
 199
 200 }
 201
 202 ktime_t alarm_expires_remaining(const struct alarm *alarm)
 203 {
 204         struct alarm_base *base = &alarm_bases[alarm->type];
 205         return ktime_sub(alarm->node.expires, base->gettime());
 206 }
 207 EXPORT_SYMBOL_GPL(alarm_expires_remaining);
 208
 209 #ifdef CONFIG_RTC_CLASS
 210 /**
 211  * alarmtimer_suspend - Suspend time callback
 212  * @dev: unused
 213  * @state: unused
 214  *
 215  * When we are going into suspend, we look through the bases
 216  * to see which is the soonest timer to expire. We then
 217  * set an rtc timer to fire that far into the future, which
 218  * will wake us from suspend.
 219  */
 220 static int alarmtimer_suspend(struct device *dev)
 221 {
 222         struct rtc_time tm;
 223         ktime_t min, now;
 224         unsigned long flags;
 225         struct rtc_device *rtc;
 226         int i;
 227         int ret;
 228
 229         spin_lock_irqsave(&freezer_delta_lock, flags);
 230         min = freezer_delta;
 231         freezer_delta = ktime_set(0, 0);
 232         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 233
 234         rtc = alarmtimer_get_rtcdev();
 235         /* If we have no rtcdev, just return */
 236         if (!rtc)
 237                 return 0;
 238
 239         /* Find the soonest timer to expire*/
 240         for (i = 0; i < ALARM_NUMTYPE; i++) {
 241                 struct alarm_base *base = &alarm_bases[i];
 242                 struct timerqueue_node *next;
 243                 ktime_t delta;
 244
 245                 spin_lock_irqsave(&base->lock, flags);
 246                 next = timerqueue_getnext(&base->timerqueue);
 247                 spin_unlock_irqrestore(&base->lock, flags);
 248                 if (!next)
 249                         continue;
 250                 delta = ktime_sub(next->expires, base->gettime());
 251                 if (!min.tv64 || (delta.tv64 < min.tv64))
 252                         min = delta;
 253         }
 254         if (min.tv64 == 0)
 255                 return 0;
 256
 257         if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
 258                 __pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
 259                 return -EBUSY;
 260         }
 261
 262         /* Setup an rtc timer to fire that far in the future */
 263         rtc_timer_cancel(rtc, &rtctimer);
 264         rtc_read_time(rtc, &tm);
 265         now = rtc_tm_to_ktime(tm);
 266         now = ktime_add(now, min);
 267
 268         /* Set alarm, if in the past reject suspend briefly to handle */
 269         ret = rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0));
 270         if (ret < 0)
 271                 __pm_wakeup_event(ws, MSEC_PER_SEC);
 272         return ret;
 273 }
 274
 275 static int alarmtimer_resume(struct device *dev)
 276 {
 277         struct rtc_device *rtc;
 278
 279         rtc = alarmtimer_get_rtcdev();
 280         if (rtc)
 281                 rtc_timer_cancel(rtc, &rtctimer);
 282         return 0;
 283 }
 284
 285 #else
 286 static int alarmtimer_suspend(struct device *dev)
 287 {
 288         return 0;
 289 }
 290
 291 static int alarmtimer_resume(struct device *dev)
 292 {
 293         return 0;
 294 }
 295 #endif
 296
 297 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 298 {
 299         ktime_t delta;
 300         unsigned long flags;
 301         struct alarm_base *base = &alarm_bases[type];
 302
 303         delta = ktime_sub(absexp, base->gettime());
 304
 305         spin_lock_irqsave(&freezer_delta_lock, flags);
 306         if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64))
 307                 freezer_delta = delta;
 308         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 309 }
 310
 311
 312 /**
 313  * alarm_init - Initialize an alarm structure
 314  * @alarm: ptr to alarm to be initialized
 315  * @type: the type of the alarm
 316  * @function: callback that is run when the alarm fires
 317  */
 318 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 319                 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 320 {
 321         timerqueue_init(&alarm->node);
 322         hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
 323                         HRTIMER_MODE_ABS);
 324         alarm->timer.function = alarmtimer_fired;
 325         alarm->function = function;
 326         alarm->type = type;
 327         alarm->state = ALARMTIMER_STATE_INACTIVE;
 328 }
 329 EXPORT_SYMBOL_GPL(alarm_init);
 330
 331 /**
 332  * alarm_start - Sets an absolute alarm to fire
 333  * @alarm: ptr to alarm to set
 334  * @start: time to run the alarm
 335  */
 336 void alarm_start(struct alarm *alarm, ktime_t start)
 337 {
 338         struct alarm_base *base = &alarm_bases[alarm->type];
 339         unsigned long flags;
 340
 341         spin_lock_irqsave(&base->lock, flags);
 342         alarm->node.expires = start;
 343         alarmtimer_enqueue(base, alarm);
 344         hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
 345         spin_unlock_irqrestore(&base->lock, flags);
 346 }
 347 EXPORT_SYMBOL_GPL(alarm_start);
 348
 349 /**
 350  * alarm_start_relative - Sets a relative alarm to fire
 351  * @alarm: ptr to alarm to set
 352  * @start: time relative to now to run the alarm
 353  */
 354 void alarm_start_relative(struct alarm *alarm, ktime_t start)
 355 {
 356         struct alarm_base *base = &alarm_bases[alarm->type];
 357
 358         start = ktime_add(start, base->gettime());
 359         alarm_start(alarm, start);
 360 }
 361 EXPORT_SYMBOL_GPL(alarm_start_relative);
 362
 363 void alarm_restart(struct alarm *alarm)
 364 {
 365         struct alarm_base *base = &alarm_bases[alarm->type];
 366         unsigned long flags;
 367
 368         spin_lock_irqsave(&base->lock, flags);
 369         hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 370         hrtimer_restart(&alarm->timer);
 371         alarmtimer_enqueue(base, alarm);
 372         spin_unlock_irqrestore(&base->lock, flags);
 373 }
 374 EXPORT_SYMBOL_GPL(alarm_restart);
 375
 376 /**
 377  * alarm_try_to_cancel - Tries to cancel an alarm timer
 378  * @alarm: ptr to alarm to be canceled
 379  *
 380  * Returns 1 if the timer was canceled, 0 if it was not running,
 381  * and -1 if the callback was running
 382  */
 383 int alarm_try_to_cancel(struct alarm *alarm)
 384 {
 385         struct alarm_base *base = &alarm_bases[alarm->type];
 386         unsigned long flags;
 387         int ret;
 388
 389         spin_lock_irqsave(&base->lock, flags);
 390         ret = hrtimer_try_to_cancel(&alarm->timer);
 391         if (ret >= 0)
 392                 alarmtimer_dequeue(base, alarm);
 393         spin_unlock_irqrestore(&base->lock, flags);
 394         return ret;
 395 }
 396 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
 397
 398
 399 /**
 400  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
 401  * @alarm: ptr to alarm to be canceled
 402  *
 403  * Returns 1 if the timer was canceled, 0 if it was not active.
 404  */
 405 int alarm_cancel(struct alarm *alarm)
 406 {
 407         for (;;) {
 408                 int ret = alarm_try_to_cancel(alarm);
 409                 if (ret >= 0)
 410                         return ret;
 411                 cpu_relax();
 412         }
 413 }
 414 EXPORT_SYMBOL_GPL(alarm_cancel);
 415
 416
 417 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
 418 {
 419         u64 overrun = 1;
 420         ktime_t delta;
 421
 422         delta = ktime_sub(now, alarm->node.expires);
 423
 424         if (delta.tv64 < 0)
 425                 return 0;
 426
 427         if (unlikely(delta.tv64 >= interval.tv64)) {
 428                 s64 incr = ktime_to_ns(interval);
 429
 430                 overrun = ktime_divns(delta, incr);
 431
 432                 alarm->node.expires = ktime_add_ns(alarm->node.expires,
 433                                                         incr*overrun);
 434
 435                 if (alarm->node.expires.tv64 > now.tv64)
 436                         return overrun;
 437                 /*
 438                  * This (and the ktime_add() below) is the
 439                  * correction for exact:
 440                  */
 441                 overrun++;
 442         }
 443
 444         alarm->node.expires = ktime_add(alarm->node.expires, interval);
 445         return overrun;
 446 }
 447 EXPORT_SYMBOL_GPL(alarm_forward);
 448
 449 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 450 {
 451         struct alarm_base *base = &alarm_bases[alarm->type];
 452
 453         return alarm_forward(alarm, base->gettime(), interval);
 454 }
 455 EXPORT_SYMBOL_GPL(alarm_forward_now);
 456
 457
 458 /**
 459  * clock2alarm - helper that converts from clockid to alarmtypes
 460  * @clockid: clockid.
 461  */
 462 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 463 {
 464         if (clockid == CLOCK_REALTIME_ALARM)
 465                 return ALARM_REALTIME;
 466         if (clockid == CLOCK_BOOTTIME_ALARM)
 467                 return ALARM_BOOTTIME;
 468         return -1;
 469 }
 470
 471 /**
 472  * alarm_handle_timer - Callback for posix timers
 473  * @alarm: alarm that fired
 474  *
 475  * Posix timer callback for expired alarm timers.
 476  */
 477 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 478                                                         ktime_t now)
 479 {
 480         unsigned long flags;
 481         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 482                                                 it.alarm.alarmtimer);
 483         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
 484
 485         spin_lock_irqsave(&ptr->it_lock, flags);
 486         if ((ptr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) {
 487                 if (posix_timer_event(ptr, 0) != 0)
 488                         ptr->it_overrun++;
 489         }
 490
 491         /* Re-add periodic timers */
 492         if (ptr->it.alarm.interval.tv64) {
 493                 ptr->it_overrun += alarm_forward(alarm, now,
 494                                                 ptr->it.alarm.interval);
 495                 result = ALARMTIMER_RESTART;
 496         }
 497         spin_unlock_irqrestore(&ptr->it_lock, flags);
 498
 499         return result;
 500 }
 501
 502 /**
 503  * alarm_clock_getres - posix getres interface
 504  * @which_clock: clockid
 505  * @tp: timespec to fill
 506  *
 507  * Returns the granularity of underlying alarm base clock
 508  */
 509 static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
 510 {
 511         if (!alarmtimer_get_rtcdev())
 512                 return -EINVAL;
 513
 514         tp->tv_sec = 0;
 515         tp->tv_nsec = hrtimer_resolution;
 516         return 0;
 517 }
 518
 519 /**
 520  * alarm_clock_get - posix clock_get interface
 521  * @which_clock: clockid
 522  * @tp: timespec to fill.
 523  *
 524  * Provides the underlying alarm base time.
 525  */
 526 static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
 527 {
 528         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 529
 530         if (!alarmtimer_get_rtcdev())
 531                 return -EINVAL;
 532
 533         *tp = ktime_to_timespec(base->gettime());
 534         return 0;
 535 }
 536
 537 /**
 538  * alarm_timer_create - posix timer_create interface
 539  * @new_timer: k_itimer pointer to manage
 540  *
 541  * Initializes the k_itimer structure.
 542  */
 543 static int alarm_timer_create(struct k_itimer *new_timer)
 544 {
 545         enum  alarmtimer_type type;
 546         struct alarm_base *base;
 547
 548         if (!alarmtimer_get_rtcdev())
 549                 return -ENOTSUPP;
 550
 551         if (!capable(CAP_WAKE_ALARM))
 552                 return -EPERM;
 553
 554         type = clock2alarm(new_timer->it_clock);
 555         base = &alarm_bases[type];
 556         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 557         return 0;
 558 }
 559
 560 /**
 561  * alarm_timer_get - posix timer_get interface
 562  * @new_timer: k_itimer pointer
 563  * @cur_setting: itimerspec data to fill
 564  *
 565  * Copies out the current itimerspec data
 566  */
 567 static void alarm_timer_get(struct k_itimer *timr,
 568                                 struct itimerspec *cur_setting)
 569 {
 570         ktime_t relative_expiry_time =
 571                 alarm_expires_remaining(&(timr->it.alarm.alarmtimer));
 572
 573         if (ktime_to_ns(relative_expiry_time) > 0) {
 574                 cur_setting->it_value = ktime_to_timespec(relative_expiry_time);
 575         } else {
 576                 cur_setting->it_value.tv_sec = 0;
 577                 cur_setting->it_value.tv_nsec = 0;
 578         }
 579
 580         cur_setting->it_interval = ktime_to_timespec(timr->it.alarm.interval);
 581 }
 582
 583 /**
 584  * alarm_timer_del - posix timer_del interface
 585  * @timr: k_itimer pointer to be deleted
 586  *
 587  * Cancels any programmed alarms for the given timer.
 588  */
 589 static int alarm_timer_del(struct k_itimer *timr)
 590 {
 591         if (!rtcdev)
 592                 return -ENOTSUPP;
 593
 594         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 595                 return TIMER_RETRY;
 596
 597         return 0;
 598 }
 599
 600 /**
 601  * alarm_timer_set - posix timer_set interface
 602  * @timr: k_itimer pointer to be deleted
 603  * @flags: timer flags
 604  * @new_setting: itimerspec to be used
 605  * @old_setting: itimerspec being replaced
 606  *
 607  * Sets the timer to new_setting, and starts the timer.
 608  */
 609 static int alarm_timer_set(struct k_itimer *timr, int flags,
 610                                 struct itimerspec *new_setting,
 611                                 struct itimerspec *old_setting)
 612 {
 613         ktime_t exp;
 614
 615         if (!rtcdev)
 616                 return -ENOTSUPP;
 617
 618         if (flags & ~TIMER_ABSTIME)
 619                 return -EINVAL;
 620
 621         if (old_setting)
 622                 alarm_timer_get(timr, old_setting);
 623
 624         /* If the timer was already set, cancel it */
 625         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 626                 return TIMER_RETRY;
 627
 628         /* start the timer */
 629         timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
 630         exp = timespec_to_ktime(new_setting->it_value);
 631         /* Convert (if necessary) to absolute time */
 632         if (flags != TIMER_ABSTIME) {
 633                 ktime_t now;
 634
 635                 now = alarm_bases[timr->it.alarm.alarmtimer.type].gettime();
 636                 exp = ktime_add(now, exp);
 637         }
 638
 639         alarm_start(&timr->it.alarm.alarmtimer, exp);
 640         return 0;
 641 }
 642
 643 /**
 644  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 645  * @alarm: ptr to alarm that fired
 646  *
 647  * Wakes up the task that set the alarmtimer
 648  */
 649 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 650                                                                 ktime_t now)
 651 {
 652         struct task_struct *task = (struct task_struct *)alarm->data;
 653
 654         alarm->data = NULL;
 655         if (task)
 656                 wake_up_process(task);
 657         return ALARMTIMER_NORESTART;
 658 }
 659
 660 /**
 661  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 662  * @alarm: ptr to alarmtimer
 663  * @absexp: absolute expiration time
 664  *
 665  * Sets the alarm timer and sleeps until it is fired or interrupted.
 666  */
 667 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
 668 {
 669         alarm->data = (void *)current;
 670         do {
 671                 set_current_state(TASK_INTERRUPTIBLE);
 672                 alarm_start(alarm, absexp);
 673                 if (likely(alarm->data))
 674                         schedule();
 675
 676                 alarm_cancel(alarm);
 677         } while (alarm->data && !signal_pending(current));
 678
 679         __set_current_state(TASK_RUNNING);
 680
 681         return (alarm->data == NULL);
 682 }
 683
 684
 685 /**
 686  * update_rmtp - Update remaining timespec value
 687  * @exp: expiration time
 688  * @type: timer type
 689  * @rmtp: user pointer to remaining timepsec value
 690  *
 691  * Helper function that fills in rmtp value with time between
 692  * now and the exp value
 693  */
 694 static int update_rmtp(ktime_t exp, enum  alarmtimer_type type,
 695                         struct timespec __user *rmtp)
 696 {
 697         struct timespec rmt;
 698         ktime_t rem;
 699
 700         rem = ktime_sub(exp, alarm_bases[type].gettime());
 701
 702         if (rem.tv64 <= 0)
 703                 return 0;
 704         rmt = ktime_to_timespec(rem);
 705
 706         if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
 707                 return -EFAULT;
 708
 709         return 1;
 710
 711 }
 712
 713 /**
 714  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 715  * @restart: ptr to restart block
 716  *
 717  * Handles restarted clock_nanosleep calls
 718  */
 719 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 720 {
 721         enum  alarmtimer_type type = restart->nanosleep.clockid;
 722         ktime_t exp;
 723         struct timespec __user  *rmtp;
 724         struct alarm alarm;
 725         int ret = 0;
 726
 727         exp.tv64 = restart->nanosleep.expires;
 728         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 729
 730         if (alarmtimer_do_nsleep(&alarm, exp))
 731                 goto out;
 732
 733         if (freezing(current))
 734                 alarmtimer_freezerset(exp, type);
 735
 736         rmtp = restart->nanosleep.rmtp;
 737         if (rmtp) {
 738                 ret = update_rmtp(exp, type, rmtp);
 739                 if (ret <= 0)
 740                         goto out;
 741         }
 742
 743
 744         /* The other values in restart are already filled in */
 745         ret = -ERESTART_RESTARTBLOCK;
 746 out:
 747         return ret;
 748 }
 749
 750 /**
 751  * alarm_timer_nsleep - alarmtimer nanosleep
 752  * @which_clock: clockid
 753  * @flags: determins abstime or relative
 754  * @tsreq: requested sleep time (abs or rel)
 755  * @rmtp: remaining sleep time saved
 756  *
 757  * Handles clock_nanosleep calls against _ALARM clockids
 758  */
 759 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 760                      struct timespec *tsreq, struct timespec __user *rmtp)
 761 {
 762         enum  alarmtimer_type type = clock2alarm(which_clock);
 763         struct alarm alarm;
 764         ktime_t exp;
 765         int ret = 0;
 766         struct restart_block *restart;
 767
 768         if (!alarmtimer_get_rtcdev())
 769                 return -ENOTSUPP;
 770
 771         if (flags & ~TIMER_ABSTIME)
 772                 return -EINVAL;
 773
 774         if (!capable(CAP_WAKE_ALARM))
 775                 return -EPERM;
 776
 777         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 778
 779         exp = timespec_to_ktime(*tsreq);
 780         /* Convert (if necessary) to absolute time */
 781         if (flags != TIMER_ABSTIME) {
 782                 ktime_t now = alarm_bases[type].gettime();
 783                 exp = ktime_add(now, exp);
 784         }
 785
 786         if (alarmtimer_do_nsleep(&alarm, exp))
 787                 goto out;
 788
 789         if (freezing(current))
 790                 alarmtimer_freezerset(exp, type);
 791
 792         /* abs timers don't set remaining time or restart */
 793         if (flags == TIMER_ABSTIME) {
 794                 ret = -ERESTARTNOHAND;
 795                 goto out;
 796         }
 797
 798         if (rmtp) {
 799                 ret = update_rmtp(exp, type, rmtp);
 800                 if (ret <= 0)
 801                         goto out;
 802         }
 803
 804         restart = &current->restart_block;
 805         restart->fn = alarm_timer_nsleep_restart;
 806         restart->nanosleep.clockid = type;
 807         restart->nanosleep.expires = exp.tv64;
 808         restart->nanosleep.rmtp = rmtp;
 809         ret = -ERESTART_RESTARTBLOCK;
 810
 811 out:
 812         return ret;
 813 }
 814
 815
 816 /* Suspend hook structures */
 817 static const struct dev_pm_ops alarmtimer_pm_ops = {
 818         .suspend = alarmtimer_suspend,
 819         .resume = alarmtimer_resume,
 820 };
 821
 822 static struct platform_driver alarmtimer_driver = {
 823         .driver = {
 824                 .name = "alarmtimer",
 825                 .pm = &alarmtimer_pm_ops,
 826         }
 827 };
 828
 829 /**
 830  * alarmtimer_init - Initialize alarm timer code
 831  *
 832  * This function initializes the alarm bases and registers
 833  * the posix clock ids.
 834  */
 835 static int __init alarmtimer_init(void)
 836 {
 837         struct platform_device *pdev;
 838         int error = 0;
 839         int i;
 840         struct k_clock alarm_clock = {
 841                 .clock_getres   = alarm_clock_getres,
 842                 .clock_get      = alarm_clock_get,
 843                 .timer_create   = alarm_timer_create,
 844                 .timer_set      = alarm_timer_set,
 845                 .timer_del      = alarm_timer_del,
 846                 .timer_get      = alarm_timer_get,
 847                 .nsleep         = alarm_timer_nsleep,
 848         };
 849
 850         alarmtimer_rtc_timer_init();
 851
 852         posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
 853         posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
 854
 855         /* Initialize alarm bases */
 856         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 857         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
 858         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 859         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
 860         for (i = 0; i < ALARM_NUMTYPE; i++) {
 861                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 862                 spin_lock_init(&alarm_bases[i].lock);
 863         }
 864
 865         error = alarmtimer_rtc_interface_setup();
 866         if (error)
 867                 return error;
 868
 869         error = platform_driver_register(&alarmtimer_driver);
 870         if (error)
 871                 goto out_if;
 872
 873         pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
 874         if (IS_ERR(pdev)) {
 875                 error = PTR_ERR(pdev);
 876                 goto out_drv;
 877         }
 878         ws = wakeup_source_register("alarmtimer");
 879         return 0;
 880
 881 out_drv:
 882         platform_driver_unregister(&alarmtimer_driver);
 883 out_if:
 884         alarmtimer_rtc_interface_remove();
 885         return error;
 886 }
 887 device_initcall(alarmtimer_init);