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         struct hrtimer          timer;
  41         ktime_t                 (*gettime)(void);
  42         clockid_t               base_clockid;
  43 } alarm_bases[ALARM_NUMTYPE];
  44
  45 /* freezer delta & lock used to handle clock_nanosleep triggered wakeups */
  46 static ktime_t freezer_delta;
  47 static DEFINE_SPINLOCK(freezer_delta_lock);
  48
  49 #ifdef CONFIG_RTC_CLASS
  50 /* rtc timer and device for setting alarm wakeups at suspend */
  51 static struct rtc_timer         rtctimer;
  52 static struct rtc_device        *rtcdev;
  53 static DEFINE_SPINLOCK(rtcdev_lock);
  54
  55 /**
  56  * has_wakealarm - check rtc device has wakealarm ability
  57  * @dev: current device
  58  * @name_ptr: name to be returned
  59  *
  60  * This helper function checks to see if the rtc device can wake
  61  * from suspend.
  62  */
  63 static int has_wakealarm(struct device *dev, void *name_ptr)
  64 {
  65         struct rtc_device *candidate = to_rtc_device(dev);
  66
  67         if (!candidate->ops->set_alarm)
  68                 return 0;
  69         if (!device_may_wakeup(candidate->dev.parent))
  70                 return 0;
  71
  72         *(const char **)name_ptr = dev_name(dev);
  73         return 1;
  74 }
  75
  76 /**
  77  * alarmtimer_get_rtcdev - Return selected rtcdevice
  78  *
  79  * This function returns the rtc device to use for wakealarms.
  80  * If one has not already been chosen, it checks to see if a
  81  * functional rtc device is available.
  82  */
  83 static struct rtc_device *alarmtimer_get_rtcdev(void)
  84 {
  85         struct device *dev;
  86         char *str;
  87         unsigned long flags;
  88         struct rtc_device *ret;
  89
  90         spin_lock_irqsave(&rtcdev_lock, flags);
  91         if (!rtcdev) {
  92                 /* Find an rtc device and init the rtc_timer */
  93                 dev = class_find_device(rtc_class, NULL, &str, has_wakealarm);
  94                 /* If we have a device then str is valid. See has_wakealarm() */
  95                 if (dev) {
  96                         rtcdev = rtc_class_open(str);
  97                         /*
  98                          * Drop the reference we got in class_find_device,
  99                          * rtc_open takes its own.
 100                          */
 101                         put_device(dev);
 102                         rtc_timer_init(&rtctimer, NULL, NULL);
 103                 }
 104         }
 105         ret = rtcdev;
 106         spin_unlock_irqrestore(&rtcdev_lock, flags);
 107
 108         return ret;
 109 }
 110 #endif
 111
 112
 113 /**
 114  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
 115  * @base: pointer to the base where the timer is being run
 116  * @alarm: pointer to alarm being enqueued.
 117  *
 118  * Adds alarm to a alarm_base timerqueue and if necessary sets
 119  * an hrtimer to run.
 120  *
 121  * Must hold base->lock when calling.
 122  */
 123 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
 124 {
 125         timerqueue_add(&base->timerqueue, &alarm->node);
 126         if (&alarm->node == timerqueue_getnext(&base->timerqueue)) {
 127                 hrtimer_try_to_cancel(&base->timer);
 128                 hrtimer_start(&base->timer, alarm->node.expires,
 129                                 HRTIMER_MODE_ABS);
 130         }
 131 }
 132
 133 /**
 134  * alarmtimer_remove - Removes an alarm timer from an alarm_base timerqueue
 135  * @base: pointer to the base where the timer is running
 136  * @alarm: pointer to alarm being removed
 137  *
 138  * Removes alarm to a alarm_base timerqueue and if necessary sets
 139  * a new timer to run.
 140  *
 141  * Must hold base->lock when calling.
 142  */
 143 static void alarmtimer_remove(struct alarm_base *base, struct alarm *alarm)
 144 {
 145         struct timerqueue_node *next = timerqueue_getnext(&base->timerqueue);
 146
 147         timerqueue_del(&base->timerqueue, &alarm->node);
 148         if (next == &alarm->node) {
 149                 hrtimer_try_to_cancel(&base->timer);
 150                 next = timerqueue_getnext(&base->timerqueue);
 151                 if (!next)
 152                         return;
 153                 hrtimer_start(&base->timer, next->expires, HRTIMER_MODE_ABS);
 154         }
 155 }
 156
 157
 158 /**
 159  * alarmtimer_fired - Handles alarm hrtimer being fired.
 160  * @timer: pointer to hrtimer being run
 161  *
 162  * When a alarm timer fires, this runs through the timerqueue to
 163  * see which alarms expired, and runs those. If there are more alarm
 164  * timers queued for the future, we set the hrtimer to fire when
 165  * when the next future alarm timer expires.
 166  */
 167 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 168 {
 169         struct alarm_base *base = container_of(timer, struct alarm_base, timer);
 170         struct timerqueue_node *next;
 171         unsigned long flags;
 172         ktime_t now;
 173         int ret = HRTIMER_NORESTART;
 174
 175         spin_lock_irqsave(&base->lock, flags);
 176         now = base->gettime();
 177         while ((next = timerqueue_getnext(&base->timerqueue))) {
 178                 struct alarm *alarm;
 179                 ktime_t expired = next->expires;
 180
 181                 if (expired.tv64 >= now.tv64)
 182                         break;
 183
 184                 alarm = container_of(next, struct alarm, node);
 185
 186                 timerqueue_del(&base->timerqueue, &alarm->node);
 187                 alarm->enabled = 0;
 188                 /* Re-add periodic timers */
 189                 if (alarm->period.tv64) {
 190                         alarm->node.expires = ktime_add(expired, alarm->period);
 191                         timerqueue_add(&base->timerqueue, &alarm->node);
 192                         alarm->enabled = 1;
 193                 }
 194                 spin_unlock_irqrestore(&base->lock, flags);
 195                 if (alarm->function)
 196                         alarm->function(alarm);
 197                 spin_lock_irqsave(&base->lock, flags);
 198         }
 199
 200         if (next) {
 201                 hrtimer_set_expires(&base->timer, next->expires);
 202                 ret = HRTIMER_RESTART;
 203         }
 204         spin_unlock_irqrestore(&base->lock, flags);
 205
 206         return ret;
 207
 208 }
 209
 210 #ifdef CONFIG_RTC_CLASS
 211 /**
 212  * alarmtimer_suspend - Suspend time callback
 213  * @dev: unused
 214  * @state: unused
 215  *
 216  * When we are going into suspend, we look through the bases
 217  * to see which is the soonest timer to expire. We then
 218  * set an rtc timer to fire that far into the future, which
 219  * will wake us from suspend.
 220  */
 221 static int alarmtimer_suspend(struct device *dev)
 222 {
 223         struct rtc_time tm;
 224         ktime_t min, now;
 225         unsigned long flags;
 226         struct rtc_device *rtc;
 227         int i;
 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         /* XXX - Should we enforce a minimum sleep time? */
 258         WARN_ON(min.tv64 < NSEC_PER_SEC);
 259
 260         /* Setup an rtc timer to fire that far in the future */
 261         rtc_timer_cancel(rtc, &rtctimer);
 262         rtc_read_time(rtc, &tm);
 263         now = rtc_tm_to_ktime(tm);
 264         now = ktime_add(now, min);
 265
 266         rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0));
 267
 268         return 0;
 269 }
 270 #else
 271 static int alarmtimer_suspend(struct device *dev)
 272 {
 273         return 0;
 274 }
 275 #endif
 276
 277 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 278 {
 279         ktime_t delta;
 280         unsigned long flags;
 281         struct alarm_base *base = &alarm_bases[type];
 282
 283         delta = ktime_sub(absexp, base->gettime());
 284
 285         spin_lock_irqsave(&freezer_delta_lock, flags);
 286         if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64))
 287                 freezer_delta = delta;
 288         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 289 }
 290
 291
 292 /**
 293  * alarm_init - Initialize an alarm structure
 294  * @alarm: ptr to alarm to be initialized
 295  * @type: the type of the alarm
 296  * @function: callback that is run when the alarm fires
 297  */
 298 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 299                 void (*function)(struct alarm *))
 300 {
 301         timerqueue_init(&alarm->node);
 302         alarm->period = ktime_set(0, 0);
 303         alarm->function = function;
 304         alarm->type = type;
 305         alarm->enabled = 0;
 306 }
 307
 308 /**
 309  * alarm_start - Sets an alarm to fire
 310  * @alarm: ptr to alarm to set
 311  * @start: time to run the alarm
 312  * @period: period at which the alarm will recur
 313  */
 314 void alarm_start(struct alarm *alarm, ktime_t start, ktime_t period)
 315 {
 316         struct alarm_base *base = &alarm_bases[alarm->type];
 317         unsigned long flags;
 318
 319         spin_lock_irqsave(&base->lock, flags);
 320         if (alarm->enabled)
 321                 alarmtimer_remove(base, alarm);
 322         alarm->node.expires = start;
 323         alarm->period = period;
 324         alarmtimer_enqueue(base, alarm);
 325         alarm->enabled = 1;
 326         spin_unlock_irqrestore(&base->lock, flags);
 327 }
 328
 329 /**
 330  * alarm_cancel - Tries to cancel an alarm timer
 331  * @alarm: ptr to alarm to be canceled
 332  */
 333 void alarm_cancel(struct alarm *alarm)
 334 {
 335         struct alarm_base *base = &alarm_bases[alarm->type];
 336         unsigned long flags;
 337
 338         spin_lock_irqsave(&base->lock, flags);
 339         if (alarm->enabled)
 340                 alarmtimer_remove(base, alarm);
 341         alarm->enabled = 0;
 342         spin_unlock_irqrestore(&base->lock, flags);
 343 }
 344
 345
 346 /**
 347  * clock2alarm - helper that converts from clockid to alarmtypes
 348  * @clockid: clockid.
 349  */
 350 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 351 {
 352         if (clockid == CLOCK_REALTIME_ALARM)
 353                 return ALARM_REALTIME;
 354         if (clockid == CLOCK_BOOTTIME_ALARM)
 355                 return ALARM_BOOTTIME;
 356         return -1;
 357 }
 358
 359 /**
 360  * alarm_handle_timer - Callback for posix timers
 361  * @alarm: alarm that fired
 362  *
 363  * Posix timer callback for expired alarm timers.
 364  */
 365 static void alarm_handle_timer(struct alarm *alarm)
 366 {
 367         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 368                                                 it.alarmtimer);
 369         if (posix_timer_event(ptr, 0) != 0)
 370                 ptr->it_overrun++;
 371 }
 372
 373 /**
 374  * alarm_clock_getres - posix getres interface
 375  * @which_clock: clockid
 376  * @tp: timespec to fill
 377  *
 378  * Returns the granularity of underlying alarm base clock
 379  */
 380 static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
 381 {
 382         clockid_t baseid = alarm_bases[clock2alarm(which_clock)].base_clockid;
 383
 384         return hrtimer_get_res(baseid, tp);
 385 }
 386
 387 /**
 388  * alarm_clock_get - posix clock_get interface
 389  * @which_clock: clockid
 390  * @tp: timespec to fill.
 391  *
 392  * Provides the underlying alarm base time.
 393  */
 394 static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
 395 {
 396         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 397
 398         *tp = ktime_to_timespec(base->gettime());
 399         return 0;
 400 }
 401
 402 /**
 403  * alarm_timer_create - posix timer_create interface
 404  * @new_timer: k_itimer pointer to manage
 405  *
 406  * Initializes the k_itimer structure.
 407  */
 408 static int alarm_timer_create(struct k_itimer *new_timer)
 409 {
 410         enum  alarmtimer_type type;
 411         struct alarm_base *base;
 412
 413         if (!capable(CAP_WAKE_ALARM))
 414                 return -EPERM;
 415
 416         type = clock2alarm(new_timer->it_clock);
 417         base = &alarm_bases[type];
 418         alarm_init(&new_timer->it.alarmtimer, type, alarm_handle_timer);
 419         return 0;
 420 }
 421
 422 /**
 423  * alarm_timer_get - posix timer_get interface
 424  * @new_timer: k_itimer pointer
 425  * @cur_setting: itimerspec data to fill
 426  *
 427  * Copies the itimerspec data out from the k_itimer
 428  */
 429 static void alarm_timer_get(struct k_itimer *timr,
 430                                 struct itimerspec *cur_setting)
 431 {
 432         cur_setting->it_interval =
 433                         ktime_to_timespec(timr->it.alarmtimer.period);
 434         cur_setting->it_value =
 435                         ktime_to_timespec(timr->it.alarmtimer.node.expires);
 436         return;
 437 }
 438
 439 /**
 440  * alarm_timer_del - posix timer_del interface
 441  * @timr: k_itimer pointer to be deleted
 442  *
 443  * Cancels any programmed alarms for the given timer.
 444  */
 445 static int alarm_timer_del(struct k_itimer *timr)
 446 {
 447         alarm_cancel(&timr->it.alarmtimer);
 448         return 0;
 449 }
 450
 451 /**
 452  * alarm_timer_set - posix timer_set interface
 453  * @timr: k_itimer pointer to be deleted
 454  * @flags: timer flags
 455  * @new_setting: itimerspec to be used
 456  * @old_setting: itimerspec being replaced
 457  *
 458  * Sets the timer to new_setting, and starts the timer.
 459  */
 460 static int alarm_timer_set(struct k_itimer *timr, int flags,
 461                                 struct itimerspec *new_setting,
 462                                 struct itimerspec *old_setting)
 463 {
 464         /* Save old values */
 465         old_setting->it_interval =
 466                         ktime_to_timespec(timr->it.alarmtimer.period);
 467         old_setting->it_value =
 468                         ktime_to_timespec(timr->it.alarmtimer.node.expires);
 469
 470         /* If the timer was already set, cancel it */
 471         alarm_cancel(&timr->it.alarmtimer);
 472
 473         /* start the timer */
 474         alarm_start(&timr->it.alarmtimer,
 475                         timespec_to_ktime(new_setting->it_value),
 476                         timespec_to_ktime(new_setting->it_interval));
 477         return 0;
 478 }
 479
 480 /**
 481  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 482  * @alarm: ptr to alarm that fired
 483  *
 484  * Wakes up the task that set the alarmtimer
 485  */
 486 static void alarmtimer_nsleep_wakeup(struct alarm *alarm)
 487 {
 488         struct task_struct *task = (struct task_struct *)alarm->data;
 489
 490         alarm->data = NULL;
 491         if (task)
 492                 wake_up_process(task);
 493 }
 494
 495 /**
 496  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 497  * @alarm: ptr to alarmtimer
 498  * @absexp: absolute expiration time
 499  *
 500  * Sets the alarm timer and sleeps until it is fired or interrupted.
 501  */
 502 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
 503 {
 504         alarm->data = (void *)current;
 505         do {
 506                 set_current_state(TASK_INTERRUPTIBLE);
 507                 alarm_start(alarm, absexp, ktime_set(0, 0));
 508                 if (likely(alarm->data))
 509                         schedule();
 510
 511                 alarm_cancel(alarm);
 512         } while (alarm->data && !signal_pending(current));
 513
 514         __set_current_state(TASK_RUNNING);
 515
 516         return (alarm->data == NULL);
 517 }
 518
 519
 520 /**
 521  * update_rmtp - Update remaining timespec value
 522  * @exp: expiration time
 523  * @type: timer type
 524  * @rmtp: user pointer to remaining timepsec value
 525  *
 526  * Helper function that fills in rmtp value with time between
 527  * now and the exp value
 528  */
 529 static int update_rmtp(ktime_t exp, enum  alarmtimer_type type,
 530                         struct timespec __user *rmtp)
 531 {
 532         struct timespec rmt;
 533         ktime_t rem;
 534
 535         rem = ktime_sub(exp, alarm_bases[type].gettime());
 536
 537         if (rem.tv64 <= 0)
 538                 return 0;
 539         rmt = ktime_to_timespec(rem);
 540
 541         if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
 542                 return -EFAULT;
 543
 544         return 1;
 545
 546 }
 547
 548 /**
 549  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 550  * @restart: ptr to restart block
 551  *
 552  * Handles restarted clock_nanosleep calls
 553  */
 554 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 555 {
 556         enum  alarmtimer_type type = restart->nanosleep.clockid;
 557         ktime_t exp;
 558         struct timespec __user  *rmtp;
 559         struct alarm alarm;
 560         int ret = 0;
 561
 562         exp.tv64 = restart->nanosleep.expires;
 563         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 564
 565         if (alarmtimer_do_nsleep(&alarm, exp))
 566                 goto out;
 567
 568         if (freezing(current))
 569                 alarmtimer_freezerset(exp, type);
 570
 571         rmtp = restart->nanosleep.rmtp;
 572         if (rmtp) {
 573                 ret = update_rmtp(exp, type, rmtp);
 574                 if (ret <= 0)
 575                         goto out;
 576         }
 577
 578
 579         /* The other values in restart are already filled in */
 580         ret = -ERESTART_RESTARTBLOCK;
 581 out:
 582         return ret;
 583 }
 584
 585 /**
 586  * alarm_timer_nsleep - alarmtimer nanosleep
 587  * @which_clock: clockid
 588  * @flags: determins abstime or relative
 589  * @tsreq: requested sleep time (abs or rel)
 590  * @rmtp: remaining sleep time saved
 591  *
 592  * Handles clock_nanosleep calls against _ALARM clockids
 593  */
 594 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 595                      struct timespec *tsreq, struct timespec __user *rmtp)
 596 {
 597         enum  alarmtimer_type type = clock2alarm(which_clock);
 598         struct alarm alarm;
 599         ktime_t exp;
 600         int ret = 0;
 601         struct restart_block *restart;
 602
 603         if (!capable(CAP_WAKE_ALARM))
 604                 return -EPERM;
 605
 606         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 607
 608         exp = timespec_to_ktime(*tsreq);
 609         /* Convert (if necessary) to absolute time */
 610         if (flags != TIMER_ABSTIME) {
 611                 ktime_t now = alarm_bases[type].gettime();
 612                 exp = ktime_add(now, exp);
 613         }
 614
 615         if (alarmtimer_do_nsleep(&alarm, exp))
 616                 goto out;
 617
 618         if (freezing(current))
 619                 alarmtimer_freezerset(exp, type);
 620
 621         /* abs timers don't set remaining time or restart */
 622         if (flags == TIMER_ABSTIME) {
 623                 ret = -ERESTARTNOHAND;
 624                 goto out;
 625         }
 626
 627         if (rmtp) {
 628                 ret = update_rmtp(exp, type, rmtp);
 629                 if (ret <= 0)
 630                         goto out;
 631         }
 632
 633         restart = &current_thread_info()->restart_block;
 634         restart->fn = alarm_timer_nsleep_restart;
 635         restart->nanosleep.clockid = type;
 636         restart->nanosleep.expires = exp.tv64;
 637         restart->nanosleep.rmtp = rmtp;
 638         ret = -ERESTART_RESTARTBLOCK;
 639
 640 out:
 641         return ret;
 642 }
 643
 644
 645 /* Suspend hook structures */
 646 static const struct dev_pm_ops alarmtimer_pm_ops = {
 647         .suspend = alarmtimer_suspend,
 648 };
 649
 650 static struct platform_driver alarmtimer_driver = {
 651         .driver = {
 652                 .name = "alarmtimer",
 653                 .pm = &alarmtimer_pm_ops,
 654         }
 655 };
 656
 657 /**
 658  * alarmtimer_init - Initialize alarm timer code
 659  *
 660  * This function initializes the alarm bases and registers
 661  * the posix clock ids.
 662  */
 663 static int __init alarmtimer_init(void)
 664 {
 665         int error = 0;
 666         int i;
 667         struct k_clock alarm_clock = {
 668                 .clock_getres   = alarm_clock_getres,
 669                 .clock_get      = alarm_clock_get,
 670                 .timer_create   = alarm_timer_create,
 671                 .timer_set      = alarm_timer_set,
 672                 .timer_del      = alarm_timer_del,
 673                 .timer_get      = alarm_timer_get,
 674                 .nsleep         = alarm_timer_nsleep,
 675         };
 676
 677         posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
 678         posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
 679
 680         /* Initialize alarm bases */
 681         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 682         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
 683         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 684         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
 685         for (i = 0; i < ALARM_NUMTYPE; i++) {
 686                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 687                 spin_lock_init(&alarm_bases[i].lock);
 688                 hrtimer_init(&alarm_bases[i].timer,
 689                                 alarm_bases[i].base_clockid,
 690                                 HRTIMER_MODE_ABS);
 691                 alarm_bases[i].timer.function = alarmtimer_fired;
 692         }
 693         error = platform_driver_register(&alarmtimer_driver);
 694         platform_device_register_simple("alarmtimer", -1, NULL, 0);
 695
 696         return error;
 697 }
 698 device_initcall(alarmtimer_init);
 699