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
  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 #else
 275 static int alarmtimer_suspend(struct device *dev)
 276 {
 277         return 0;
 278 }
 279 #endif
 280
 281 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 282 {
 283         ktime_t delta;
 284         unsigned long flags;
 285         struct alarm_base *base = &alarm_bases[type];
 286
 287         delta = ktime_sub(absexp, base->gettime());
 288
 289         spin_lock_irqsave(&freezer_delta_lock, flags);
 290         if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64))
 291                 freezer_delta = delta;
 292         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 293 }
 294
 295
 296 /**
 297  * alarm_init - Initialize an alarm structure
 298  * @alarm: ptr to alarm to be initialized
 299  * @type: the type of the alarm
 300  * @function: callback that is run when the alarm fires
 301  */
 302 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 303                 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 304 {
 305         timerqueue_init(&alarm->node);
 306         hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
 307                         HRTIMER_MODE_ABS);
 308         alarm->timer.function = alarmtimer_fired;
 309         alarm->function = function;
 310         alarm->type = type;
 311         alarm->state = ALARMTIMER_STATE_INACTIVE;
 312 }
 313 EXPORT_SYMBOL_GPL(alarm_init);
 314
 315 /**
 316  * alarm_start - Sets an absolute alarm to fire
 317  * @alarm: ptr to alarm to set
 318  * @start: time to run the alarm
 319  */
 320 int alarm_start(struct alarm *alarm, ktime_t start)
 321 {
 322         struct alarm_base *base = &alarm_bases[alarm->type];
 323         unsigned long flags;
 324         int ret;
 325
 326         spin_lock_irqsave(&base->lock, flags);
 327         alarm->node.expires = start;
 328         alarmtimer_enqueue(base, alarm);
 329         ret = hrtimer_start(&alarm->timer, alarm->node.expires,
 330                                 HRTIMER_MODE_ABS);
 331         spin_unlock_irqrestore(&base->lock, flags);
 332         return ret;
 333 }
 334 EXPORT_SYMBOL_GPL(alarm_start);
 335
 336 /**
 337  * alarm_start_relative - Sets a relative alarm to fire
 338  * @alarm: ptr to alarm to set
 339  * @start: time relative to now to run the alarm
 340  */
 341 int alarm_start_relative(struct alarm *alarm, ktime_t start)
 342 {
 343         struct alarm_base *base = &alarm_bases[alarm->type];
 344
 345         start = ktime_add(start, base->gettime());
 346         return alarm_start(alarm, start);
 347 }
 348 EXPORT_SYMBOL_GPL(alarm_start_relative);
 349
 350 void alarm_restart(struct alarm *alarm)
 351 {
 352         struct alarm_base *base = &alarm_bases[alarm->type];
 353         unsigned long flags;
 354
 355         spin_lock_irqsave(&base->lock, flags);
 356         hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 357         hrtimer_restart(&alarm->timer);
 358         alarmtimer_enqueue(base, alarm);
 359         spin_unlock_irqrestore(&base->lock, flags);
 360 }
 361 EXPORT_SYMBOL_GPL(alarm_restart);
 362
 363 /**
 364  * alarm_try_to_cancel - Tries to cancel an alarm timer
 365  * @alarm: ptr to alarm to be canceled
 366  *
 367  * Returns 1 if the timer was canceled, 0 if it was not running,
 368  * and -1 if the callback was running
 369  */
 370 int alarm_try_to_cancel(struct alarm *alarm)
 371 {
 372         struct alarm_base *base = &alarm_bases[alarm->type];
 373         unsigned long flags;
 374         int ret;
 375
 376         spin_lock_irqsave(&base->lock, flags);
 377         ret = hrtimer_try_to_cancel(&alarm->timer);
 378         if (ret >= 0)
 379                 alarmtimer_dequeue(base, alarm);
 380         spin_unlock_irqrestore(&base->lock, flags);
 381         return ret;
 382 }
 383 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
 384
 385
 386 /**
 387  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
 388  * @alarm: ptr to alarm to be canceled
 389  *
 390  * Returns 1 if the timer was canceled, 0 if it was not active.
 391  */
 392 int alarm_cancel(struct alarm *alarm)
 393 {
 394         for (;;) {
 395                 int ret = alarm_try_to_cancel(alarm);
 396                 if (ret >= 0)
 397                         return ret;
 398                 cpu_relax();
 399         }
 400 }
 401 EXPORT_SYMBOL_GPL(alarm_cancel);
 402
 403
 404 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
 405 {
 406         u64 overrun = 1;
 407         ktime_t delta;
 408
 409         delta = ktime_sub(now, alarm->node.expires);
 410
 411         if (delta.tv64 < 0)
 412                 return 0;
 413
 414         if (unlikely(delta.tv64 >= interval.tv64)) {
 415                 s64 incr = ktime_to_ns(interval);
 416
 417                 overrun = ktime_divns(delta, incr);
 418
 419                 alarm->node.expires = ktime_add_ns(alarm->node.expires,
 420                                                         incr*overrun);
 421
 422                 if (alarm->node.expires.tv64 > now.tv64)
 423                         return overrun;
 424                 /*
 425                  * This (and the ktime_add() below) is the
 426                  * correction for exact:
 427                  */
 428                 overrun++;
 429         }
 430
 431         alarm->node.expires = ktime_add(alarm->node.expires, interval);
 432         return overrun;
 433 }
 434 EXPORT_SYMBOL_GPL(alarm_forward);
 435
 436 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 437 {
 438         struct alarm_base *base = &alarm_bases[alarm->type];
 439
 440         return alarm_forward(alarm, base->gettime(), interval);
 441 }
 442 EXPORT_SYMBOL_GPL(alarm_forward_now);
 443
 444
 445 /**
 446  * clock2alarm - helper that converts from clockid to alarmtypes
 447  * @clockid: clockid.
 448  */
 449 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 450 {
 451         if (clockid == CLOCK_REALTIME_ALARM)
 452                 return ALARM_REALTIME;
 453         if (clockid == CLOCK_BOOTTIME_ALARM)
 454                 return ALARM_BOOTTIME;
 455         return -1;
 456 }
 457
 458 /**
 459  * alarm_handle_timer - Callback for posix timers
 460  * @alarm: alarm that fired
 461  *
 462  * Posix timer callback for expired alarm timers.
 463  */
 464 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 465                                                         ktime_t now)
 466 {
 467         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 468                                                 it.alarm.alarmtimer);
 469         if (posix_timer_event(ptr, 0) != 0)
 470                 ptr->it_overrun++;
 471
 472         /* Re-add periodic timers */
 473         if (ptr->it.alarm.interval.tv64) {
 474                 ptr->it_overrun += alarm_forward(alarm, now,
 475                                                 ptr->it.alarm.interval);
 476                 return ALARMTIMER_RESTART;
 477         }
 478         return ALARMTIMER_NORESTART;
 479 }
 480
 481 /**
 482  * alarm_clock_getres - posix getres interface
 483  * @which_clock: clockid
 484  * @tp: timespec to fill
 485  *
 486  * Returns the granularity of underlying alarm base clock
 487  */
 488 static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
 489 {
 490         clockid_t baseid = alarm_bases[clock2alarm(which_clock)].base_clockid;
 491
 492         if (!alarmtimer_get_rtcdev())
 493                 return -EINVAL;
 494
 495         return hrtimer_get_res(baseid, tp);
 496 }
 497
 498 /**
 499  * alarm_clock_get - posix clock_get interface
 500  * @which_clock: clockid
 501  * @tp: timespec to fill.
 502  *
 503  * Provides the underlying alarm base time.
 504  */
 505 static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
 506 {
 507         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 508
 509         if (!alarmtimer_get_rtcdev())
 510                 return -EINVAL;
 511
 512         *tp = ktime_to_timespec(base->gettime());
 513         return 0;
 514 }
 515
 516 /**
 517  * alarm_timer_create - posix timer_create interface
 518  * @new_timer: k_itimer pointer to manage
 519  *
 520  * Initializes the k_itimer structure.
 521  */
 522 static int alarm_timer_create(struct k_itimer *new_timer)
 523 {
 524         enum  alarmtimer_type type;
 525         struct alarm_base *base;
 526
 527         if (!alarmtimer_get_rtcdev())
 528                 return -ENOTSUPP;
 529
 530         if (!capable(CAP_WAKE_ALARM))
 531                 return -EPERM;
 532
 533         type = clock2alarm(new_timer->it_clock);
 534         base = &alarm_bases[type];
 535         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 536         return 0;
 537 }
 538
 539 /**
 540  * alarm_timer_get - posix timer_get interface
 541  * @new_timer: k_itimer pointer
 542  * @cur_setting: itimerspec data to fill
 543  *
 544  * Copies the itimerspec data out from the k_itimer
 545  */
 546 static void alarm_timer_get(struct k_itimer *timr,
 547                                 struct itimerspec *cur_setting)
 548 {
 549         memset(cur_setting, 0, sizeof(struct itimerspec));
 550
 551         cur_setting->it_interval =
 552                         ktime_to_timespec(timr->it.alarm.interval);
 553         cur_setting->it_value =
 554                 ktime_to_timespec(timr->it.alarm.alarmtimer.node.expires);
 555         return;
 556 }
 557
 558 /**
 559  * alarm_timer_del - posix timer_del interface
 560  * @timr: k_itimer pointer to be deleted
 561  *
 562  * Cancels any programmed alarms for the given timer.
 563  */
 564 static int alarm_timer_del(struct k_itimer *timr)
 565 {
 566         if (!rtcdev)
 567                 return -ENOTSUPP;
 568
 569         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 570                 return TIMER_RETRY;
 571
 572         return 0;
 573 }
 574
 575 /**
 576  * alarm_timer_set - posix timer_set interface
 577  * @timr: k_itimer pointer to be deleted
 578  * @flags: timer flags
 579  * @new_setting: itimerspec to be used
 580  * @old_setting: itimerspec being replaced
 581  *
 582  * Sets the timer to new_setting, and starts the timer.
 583  */
 584 static int alarm_timer_set(struct k_itimer *timr, int flags,
 585                                 struct itimerspec *new_setting,
 586                                 struct itimerspec *old_setting)
 587 {
 588         ktime_t exp;
 589
 590         if (!rtcdev)
 591                 return -ENOTSUPP;
 592
 593         if (flags & ~TIMER_ABSTIME)
 594                 return -EINVAL;
 595
 596         if (old_setting)
 597                 alarm_timer_get(timr, old_setting);
 598
 599         /* If the timer was already set, cancel it */
 600         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 601                 return TIMER_RETRY;
 602
 603         /* start the timer */
 604         timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
 605         exp = timespec_to_ktime(new_setting->it_value);
 606         /* Convert (if necessary) to absolute time */
 607         if (flags != TIMER_ABSTIME) {
 608                 ktime_t now;
 609
 610                 now = alarm_bases[timr->it.alarm.alarmtimer.type].gettime();
 611                 exp = ktime_add(now, exp);
 612         }
 613
 614         alarm_start(&timr->it.alarm.alarmtimer, exp);
 615         return 0;
 616 }
 617
 618 /**
 619  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 620  * @alarm: ptr to alarm that fired
 621  *
 622  * Wakes up the task that set the alarmtimer
 623  */
 624 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 625                                                                 ktime_t now)
 626 {
 627         struct task_struct *task = (struct task_struct *)alarm->data;
 628
 629         alarm->data = NULL;
 630         if (task)
 631                 wake_up_process(task);
 632         return ALARMTIMER_NORESTART;
 633 }
 634
 635 /**
 636  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 637  * @alarm: ptr to alarmtimer
 638  * @absexp: absolute expiration time
 639  *
 640  * Sets the alarm timer and sleeps until it is fired or interrupted.
 641  */
 642 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
 643 {
 644         alarm->data = (void *)current;
 645         do {
 646                 set_current_state(TASK_INTERRUPTIBLE);
 647                 alarm_start(alarm, absexp);
 648                 if (likely(alarm->data))
 649                         schedule();
 650
 651                 alarm_cancel(alarm);
 652         } while (alarm->data && !signal_pending(current));
 653
 654         __set_current_state(TASK_RUNNING);
 655
 656         return (alarm->data == NULL);
 657 }
 658
 659
 660 /**
 661  * update_rmtp - Update remaining timespec value
 662  * @exp: expiration time
 663  * @type: timer type
 664  * @rmtp: user pointer to remaining timepsec value
 665  *
 666  * Helper function that fills in rmtp value with time between
 667  * now and the exp value
 668  */
 669 static int update_rmtp(ktime_t exp, enum  alarmtimer_type type,
 670                         struct timespec __user *rmtp)
 671 {
 672         struct timespec rmt;
 673         ktime_t rem;
 674
 675         rem = ktime_sub(exp, alarm_bases[type].gettime());
 676
 677         if (rem.tv64 <= 0)
 678                 return 0;
 679         rmt = ktime_to_timespec(rem);
 680
 681         if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
 682                 return -EFAULT;
 683
 684         return 1;
 685
 686 }
 687
 688 /**
 689  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 690  * @restart: ptr to restart block
 691  *
 692  * Handles restarted clock_nanosleep calls
 693  */
 694 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 695 {
 696         enum  alarmtimer_type type = restart->nanosleep.clockid;
 697         ktime_t exp;
 698         struct timespec __user  *rmtp;
 699         struct alarm alarm;
 700         int ret = 0;
 701
 702         exp.tv64 = restart->nanosleep.expires;
 703         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 704
 705         if (alarmtimer_do_nsleep(&alarm, exp))
 706                 goto out;
 707
 708         if (freezing(current))
 709                 alarmtimer_freezerset(exp, type);
 710
 711         rmtp = restart->nanosleep.rmtp;
 712         if (rmtp) {
 713                 ret = update_rmtp(exp, type, rmtp);
 714                 if (ret <= 0)
 715                         goto out;
 716         }
 717
 718
 719         /* The other values in restart are already filled in */
 720         ret = -ERESTART_RESTARTBLOCK;
 721 out:
 722         return ret;
 723 }
 724
 725 /**
 726  * alarm_timer_nsleep - alarmtimer nanosleep
 727  * @which_clock: clockid
 728  * @flags: determins abstime or relative
 729  * @tsreq: requested sleep time (abs or rel)
 730  * @rmtp: remaining sleep time saved
 731  *
 732  * Handles clock_nanosleep calls against _ALARM clockids
 733  */
 734 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 735                      struct timespec *tsreq, struct timespec __user *rmtp)
 736 {
 737         enum  alarmtimer_type type = clock2alarm(which_clock);
 738         struct alarm alarm;
 739         ktime_t exp;
 740         int ret = 0;
 741         struct restart_block *restart;
 742
 743         if (!alarmtimer_get_rtcdev())
 744                 return -ENOTSUPP;
 745
 746         if (flags & ~TIMER_ABSTIME)
 747                 return -EINVAL;
 748
 749         if (!capable(CAP_WAKE_ALARM))
 750                 return -EPERM;
 751
 752         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 753
 754         exp = timespec_to_ktime(*tsreq);
 755         /* Convert (if necessary) to absolute time */
 756         if (flags != TIMER_ABSTIME) {
 757                 ktime_t now = alarm_bases[type].gettime();
 758                 exp = ktime_add(now, exp);
 759         }
 760
 761         if (alarmtimer_do_nsleep(&alarm, exp))
 762                 goto out;
 763
 764         if (freezing(current))
 765                 alarmtimer_freezerset(exp, type);
 766
 767         /* abs timers don't set remaining time or restart */
 768         if (flags == TIMER_ABSTIME) {
 769                 ret = -ERESTARTNOHAND;
 770                 goto out;
 771         }
 772
 773         if (rmtp) {
 774                 ret = update_rmtp(exp, type, rmtp);
 775                 if (ret <= 0)
 776                         goto out;
 777         }
 778
 779         restart = &current_thread_info()->restart_block;
 780         restart->fn = alarm_timer_nsleep_restart;
 781         restart->nanosleep.clockid = type;
 782         restart->nanosleep.expires = exp.tv64;
 783         restart->nanosleep.rmtp = rmtp;
 784         ret = -ERESTART_RESTARTBLOCK;
 785
 786 out:
 787         return ret;
 788 }
 789
 790
 791 /* Suspend hook structures */
 792 static const struct dev_pm_ops alarmtimer_pm_ops = {
 793         .suspend = alarmtimer_suspend,
 794 };
 795
 796 static struct platform_driver alarmtimer_driver = {
 797         .driver = {
 798                 .name = "alarmtimer",
 799                 .pm = &alarmtimer_pm_ops,
 800         }
 801 };
 802
 803 /**
 804  * alarmtimer_init - Initialize alarm timer code
 805  *
 806  * This function initializes the alarm bases and registers
 807  * the posix clock ids.
 808  */
 809 static int __init alarmtimer_init(void)
 810 {
 811         struct platform_device *pdev;
 812         int error = 0;
 813         int i;
 814         struct k_clock alarm_clock = {
 815                 .clock_getres   = alarm_clock_getres,
 816                 .clock_get      = alarm_clock_get,
 817                 .timer_create   = alarm_timer_create,
 818                 .timer_set      = alarm_timer_set,
 819                 .timer_del      = alarm_timer_del,
 820                 .timer_get      = alarm_timer_get,
 821                 .nsleep         = alarm_timer_nsleep,
 822         };
 823
 824         alarmtimer_rtc_timer_init();
 825
 826         posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
 827         posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
 828
 829         /* Initialize alarm bases */
 830         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 831         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
 832         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 833         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
 834         for (i = 0; i < ALARM_NUMTYPE; i++) {
 835                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 836                 spin_lock_init(&alarm_bases[i].lock);
 837         }
 838
 839         error = alarmtimer_rtc_interface_setup();
 840         if (error)
 841                 return error;
 842
 843         error = platform_driver_register(&alarmtimer_driver);
 844         if (error)
 845                 goto out_if;
 846
 847         pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
 848         if (IS_ERR(pdev)) {
 849                 error = PTR_ERR(pdev);
 850                 goto out_drv;
 851         }
 852         ws = wakeup_source_register("alarmtimer");
 853         return 0;
 854
 855 out_drv:
 856         platform_driver_unregister(&alarmtimer_driver);
 857 out_if:
 858         alarmtimer_rtc_interface_remove();
 859         return error;
 860 }
 861 device_initcall(alarmtimer_init);