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 #ifdef CONFIG_RTC_CLASS
 203 /**
 204  * alarmtimer_suspend - Suspend time callback
 205  * @dev: unused
 206  * @state: unused
 207  *
 208  * When we are going into suspend, we look through the bases
 209  * to see which is the soonest timer to expire. We then
 210  * set an rtc timer to fire that far into the future, which
 211  * will wake us from suspend.
 212  */
 213 static int alarmtimer_suspend(struct device *dev)
 214 {
 215         struct rtc_time tm;
 216         ktime_t min, now;
 217         unsigned long flags;
 218         struct rtc_device *rtc;
 219         int i;
 220         int ret;
 221
 222         spin_lock_irqsave(&freezer_delta_lock, flags);
 223         min = freezer_delta;
 224         freezer_delta = ktime_set(0, 0);
 225         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 226
 227         rtc = alarmtimer_get_rtcdev();
 228         /* If we have no rtcdev, just return */
 229         if (!rtc)
 230                 return 0;
 231
 232         /* Find the soonest timer to expire*/
 233         for (i = 0; i < ALARM_NUMTYPE; i++) {
 234                 struct alarm_base *base = &alarm_bases[i];
 235                 struct timerqueue_node *next;
 236                 ktime_t delta;
 237
 238                 spin_lock_irqsave(&base->lock, flags);
 239                 next = timerqueue_getnext(&base->timerqueue);
 240                 spin_unlock_irqrestore(&base->lock, flags);
 241                 if (!next)
 242                         continue;
 243                 delta = ktime_sub(next->expires, base->gettime());
 244                 if (!min.tv64 || (delta.tv64 < min.tv64))
 245                         min = delta;
 246         }
 247         if (min.tv64 == 0)
 248                 return 0;
 249
 250         if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
 251                 __pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
 252                 return -EBUSY;
 253         }
 254
 255         /* Setup an rtc timer to fire that far in the future */
 256         rtc_timer_cancel(rtc, &rtctimer);
 257         rtc_read_time(rtc, &tm);
 258         now = rtc_tm_to_ktime(tm);
 259         now = ktime_add(now, min);
 260
 261         /* Set alarm, if in the past reject suspend briefly to handle */
 262         ret = rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0));
 263         if (ret < 0)
 264                 __pm_wakeup_event(ws, MSEC_PER_SEC);
 265         return ret;
 266 }
 267 #else
 268 static int alarmtimer_suspend(struct device *dev)
 269 {
 270         return 0;
 271 }
 272 #endif
 273
 274 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 275 {
 276         ktime_t delta;
 277         unsigned long flags;
 278         struct alarm_base *base = &alarm_bases[type];
 279
 280         delta = ktime_sub(absexp, base->gettime());
 281
 282         spin_lock_irqsave(&freezer_delta_lock, flags);
 283         if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64))
 284                 freezer_delta = delta;
 285         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 286 }
 287
 288
 289 /**
 290  * alarm_init - Initialize an alarm structure
 291  * @alarm: ptr to alarm to be initialized
 292  * @type: the type of the alarm
 293  * @function: callback that is run when the alarm fires
 294  */
 295 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 296                 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 297 {
 298         timerqueue_init(&alarm->node);
 299         hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
 300                         HRTIMER_MODE_ABS);
 301         alarm->timer.function = alarmtimer_fired;
 302         alarm->function = function;
 303         alarm->type = type;
 304         alarm->state = ALARMTIMER_STATE_INACTIVE;
 305 }
 306
 307 /**
 308  * alarm_start - Sets an alarm to fire
 309  * @alarm: ptr to alarm to set
 310  * @start: time to run the alarm
 311  */
 312 int alarm_start(struct alarm *alarm, ktime_t start)
 313 {
 314         struct alarm_base *base = &alarm_bases[alarm->type];
 315         unsigned long flags;
 316         int ret;
 317
 318         spin_lock_irqsave(&base->lock, flags);
 319         alarm->node.expires = start;
 320         alarmtimer_enqueue(base, alarm);
 321         ret = hrtimer_start(&alarm->timer, alarm->node.expires,
 322                                 HRTIMER_MODE_ABS);
 323         spin_unlock_irqrestore(&base->lock, flags);
 324         return ret;
 325 }
 326
 327 /**
 328  * alarm_try_to_cancel - Tries to cancel an alarm timer
 329  * @alarm: ptr to alarm to be canceled
 330  *
 331  * Returns 1 if the timer was canceled, 0 if it was not running,
 332  * and -1 if the callback was running
 333  */
 334 int alarm_try_to_cancel(struct alarm *alarm)
 335 {
 336         struct alarm_base *base = &alarm_bases[alarm->type];
 337         unsigned long flags;
 338         int ret;
 339
 340         spin_lock_irqsave(&base->lock, flags);
 341         ret = hrtimer_try_to_cancel(&alarm->timer);
 342         if (ret >= 0)
 343                 alarmtimer_dequeue(base, alarm);
 344         spin_unlock_irqrestore(&base->lock, flags);
 345         return ret;
 346 }
 347
 348
 349 /**
 350  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
 351  * @alarm: ptr to alarm to be canceled
 352  *
 353  * Returns 1 if the timer was canceled, 0 if it was not active.
 354  */
 355 int alarm_cancel(struct alarm *alarm)
 356 {
 357         for (;;) {
 358                 int ret = alarm_try_to_cancel(alarm);
 359                 if (ret >= 0)
 360                         return ret;
 361                 cpu_relax();
 362         }
 363 }
 364
 365
 366 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
 367 {
 368         u64 overrun = 1;
 369         ktime_t delta;
 370
 371         delta = ktime_sub(now, alarm->node.expires);
 372
 373         if (delta.tv64 < 0)
 374                 return 0;
 375
 376         if (unlikely(delta.tv64 >= interval.tv64)) {
 377                 s64 incr = ktime_to_ns(interval);
 378
 379                 overrun = ktime_divns(delta, incr);
 380
 381                 alarm->node.expires = ktime_add_ns(alarm->node.expires,
 382                                                         incr*overrun);
 383
 384                 if (alarm->node.expires.tv64 > now.tv64)
 385                         return overrun;
 386                 /*
 387                  * This (and the ktime_add() below) is the
 388                  * correction for exact:
 389                  */
 390                 overrun++;
 391         }
 392
 393         alarm->node.expires = ktime_add(alarm->node.expires, interval);
 394         return overrun;
 395 }
 396
 397
 398
 399
 400 /**
 401  * clock2alarm - helper that converts from clockid to alarmtypes
 402  * @clockid: clockid.
 403  */
 404 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 405 {
 406         if (clockid == CLOCK_REALTIME_ALARM)
 407                 return ALARM_REALTIME;
 408         if (clockid == CLOCK_BOOTTIME_ALARM)
 409                 return ALARM_BOOTTIME;
 410         return -1;
 411 }
 412
 413 /**
 414  * alarm_handle_timer - Callback for posix timers
 415  * @alarm: alarm that fired
 416  *
 417  * Posix timer callback for expired alarm timers.
 418  */
 419 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 420                                                         ktime_t now)
 421 {
 422         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 423                                                 it.alarm.alarmtimer);
 424         if ((ptr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) {
 425                 if (posix_timer_event(ptr, 0) != 0)
 426                         ptr->it_overrun++;
 427         }
 428
 429         /* Re-add periodic timers */
 430         if (ptr->it.alarm.interval.tv64) {
 431                 ptr->it_overrun += alarm_forward(alarm, now,
 432                                                 ptr->it.alarm.interval);
 433                 return ALARMTIMER_RESTART;
 434         }
 435         return ALARMTIMER_NORESTART;
 436 }
 437
 438 /**
 439  * alarm_clock_getres - posix getres interface
 440  * @which_clock: clockid
 441  * @tp: timespec to fill
 442  *
 443  * Returns the granularity of underlying alarm base clock
 444  */
 445 static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
 446 {
 447         clockid_t baseid = alarm_bases[clock2alarm(which_clock)].base_clockid;
 448
 449         if (!alarmtimer_get_rtcdev())
 450                 return -EINVAL;
 451
 452         return hrtimer_get_res(baseid, tp);
 453 }
 454
 455 /**
 456  * alarm_clock_get - posix clock_get interface
 457  * @which_clock: clockid
 458  * @tp: timespec to fill.
 459  *
 460  * Provides the underlying alarm base time.
 461  */
 462 static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
 463 {
 464         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 465
 466         if (!alarmtimer_get_rtcdev())
 467                 return -EINVAL;
 468
 469         *tp = ktime_to_timespec(base->gettime());
 470         return 0;
 471 }
 472
 473 /**
 474  * alarm_timer_create - posix timer_create interface
 475  * @new_timer: k_itimer pointer to manage
 476  *
 477  * Initializes the k_itimer structure.
 478  */
 479 static int alarm_timer_create(struct k_itimer *new_timer)
 480 {
 481         enum  alarmtimer_type type;
 482         struct alarm_base *base;
 483
 484         if (!alarmtimer_get_rtcdev())
 485                 return -ENOTSUPP;
 486
 487         if (!capable(CAP_WAKE_ALARM))
 488                 return -EPERM;
 489
 490         type = clock2alarm(new_timer->it_clock);
 491         base = &alarm_bases[type];
 492         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 493         return 0;
 494 }
 495
 496 /**
 497  * alarm_timer_get - posix timer_get interface
 498  * @new_timer: k_itimer pointer
 499  * @cur_setting: itimerspec data to fill
 500  *
 501  * Copies the itimerspec data out from the k_itimer
 502  */
 503 static void alarm_timer_get(struct k_itimer *timr,
 504                                 struct itimerspec *cur_setting)
 505 {
 506         memset(cur_setting, 0, sizeof(struct itimerspec));
 507
 508         cur_setting->it_interval =
 509                         ktime_to_timespec(timr->it.alarm.interval);
 510         cur_setting->it_value =
 511                 ktime_to_timespec(timr->it.alarm.alarmtimer.node.expires);
 512         return;
 513 }
 514
 515 /**
 516  * alarm_timer_del - posix timer_del interface
 517  * @timr: k_itimer pointer to be deleted
 518  *
 519  * Cancels any programmed alarms for the given timer.
 520  */
 521 static int alarm_timer_del(struct k_itimer *timr)
 522 {
 523         if (!rtcdev)
 524                 return -ENOTSUPP;
 525
 526         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 527                 return TIMER_RETRY;
 528
 529         return 0;
 530 }
 531
 532 /**
 533  * alarm_timer_set - posix timer_set interface
 534  * @timr: k_itimer pointer to be deleted
 535  * @flags: timer flags
 536  * @new_setting: itimerspec to be used
 537  * @old_setting: itimerspec being replaced
 538  *
 539  * Sets the timer to new_setting, and starts the timer.
 540  */
 541 static int alarm_timer_set(struct k_itimer *timr, int flags,
 542                                 struct itimerspec *new_setting,
 543                                 struct itimerspec *old_setting)
 544 {
 545         ktime_t exp;
 546
 547         if (!rtcdev)
 548                 return -ENOTSUPP;
 549
 550         if (flags & ~TIMER_ABSTIME)
 551                 return -EINVAL;
 552
 553         if (old_setting)
 554                 alarm_timer_get(timr, old_setting);
 555
 556         /* If the timer was already set, cancel it */
 557         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 558                 return TIMER_RETRY;
 559
 560         /* start the timer */
 561         timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
 562         exp = timespec_to_ktime(new_setting->it_value);
 563         /* Convert (if necessary) to absolute time */
 564         if (flags != TIMER_ABSTIME) {
 565                 ktime_t now;
 566
 567                 now = alarm_bases[timr->it.alarm.alarmtimer.type].gettime();
 568                 exp = ktime_add(now, exp);
 569         }
 570
 571         alarm_start(&timr->it.alarm.alarmtimer, exp);
 572         return 0;
 573 }
 574
 575 /**
 576  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 577  * @alarm: ptr to alarm that fired
 578  *
 579  * Wakes up the task that set the alarmtimer
 580  */
 581 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 582                                                                 ktime_t now)
 583 {
 584         struct task_struct *task = (struct task_struct *)alarm->data;
 585
 586         alarm->data = NULL;
 587         if (task)
 588                 wake_up_process(task);
 589         return ALARMTIMER_NORESTART;
 590 }
 591
 592 /**
 593  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 594  * @alarm: ptr to alarmtimer
 595  * @absexp: absolute expiration time
 596  *
 597  * Sets the alarm timer and sleeps until it is fired or interrupted.
 598  */
 599 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
 600 {
 601         alarm->data = (void *)current;
 602         do {
 603                 set_current_state(TASK_INTERRUPTIBLE);
 604                 alarm_start(alarm, absexp);
 605                 if (likely(alarm->data))
 606                         schedule();
 607
 608                 alarm_cancel(alarm);
 609         } while (alarm->data && !signal_pending(current));
 610
 611         __set_current_state(TASK_RUNNING);
 612
 613         return (alarm->data == NULL);
 614 }
 615
 616
 617 /**
 618  * update_rmtp - Update remaining timespec value
 619  * @exp: expiration time
 620  * @type: timer type
 621  * @rmtp: user pointer to remaining timepsec value
 622  *
 623  * Helper function that fills in rmtp value with time between
 624  * now and the exp value
 625  */
 626 static int update_rmtp(ktime_t exp, enum  alarmtimer_type type,
 627                         struct timespec __user *rmtp)
 628 {
 629         struct timespec rmt;
 630         ktime_t rem;
 631
 632         rem = ktime_sub(exp, alarm_bases[type].gettime());
 633
 634         if (rem.tv64 <= 0)
 635                 return 0;
 636         rmt = ktime_to_timespec(rem);
 637
 638         if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
 639                 return -EFAULT;
 640
 641         return 1;
 642
 643 }
 644
 645 /**
 646  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 647  * @restart: ptr to restart block
 648  *
 649  * Handles restarted clock_nanosleep calls
 650  */
 651 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 652 {
 653         enum  alarmtimer_type type = restart->nanosleep.clockid;
 654         ktime_t exp;
 655         struct timespec __user  *rmtp;
 656         struct alarm alarm;
 657         int ret = 0;
 658
 659         exp.tv64 = restart->nanosleep.expires;
 660         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 661
 662         if (alarmtimer_do_nsleep(&alarm, exp))
 663                 goto out;
 664
 665         if (freezing(current))
 666                 alarmtimer_freezerset(exp, type);
 667
 668         rmtp = restart->nanosleep.rmtp;
 669         if (rmtp) {
 670                 ret = update_rmtp(exp, type, rmtp);
 671                 if (ret <= 0)
 672                         goto out;
 673         }
 674
 675
 676         /* The other values in restart are already filled in */
 677         ret = -ERESTART_RESTARTBLOCK;
 678 out:
 679         return ret;
 680 }
 681
 682 /**
 683  * alarm_timer_nsleep - alarmtimer nanosleep
 684  * @which_clock: clockid
 685  * @flags: determins abstime or relative
 686  * @tsreq: requested sleep time (abs or rel)
 687  * @rmtp: remaining sleep time saved
 688  *
 689  * Handles clock_nanosleep calls against _ALARM clockids
 690  */
 691 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 692                      struct timespec *tsreq, struct timespec __user *rmtp)
 693 {
 694         enum  alarmtimer_type type = clock2alarm(which_clock);
 695         struct alarm alarm;
 696         ktime_t exp;
 697         int ret = 0;
 698         struct restart_block *restart;
 699
 700         if (!alarmtimer_get_rtcdev())
 701                 return -ENOTSUPP;
 702
 703         if (flags & ~TIMER_ABSTIME)
 704                 return -EINVAL;
 705
 706         if (!capable(CAP_WAKE_ALARM))
 707                 return -EPERM;
 708
 709         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 710
 711         exp = timespec_to_ktime(*tsreq);
 712         /* Convert (if necessary) to absolute time */
 713         if (flags != TIMER_ABSTIME) {
 714                 ktime_t now = alarm_bases[type].gettime();
 715                 exp = ktime_add(now, exp);
 716         }
 717
 718         if (alarmtimer_do_nsleep(&alarm, exp))
 719                 goto out;
 720
 721         if (freezing(current))
 722                 alarmtimer_freezerset(exp, type);
 723
 724         /* abs timers don't set remaining time or restart */
 725         if (flags == TIMER_ABSTIME) {
 726                 ret = -ERESTARTNOHAND;
 727                 goto out;
 728         }
 729
 730         if (rmtp) {
 731                 ret = update_rmtp(exp, type, rmtp);
 732                 if (ret <= 0)
 733                         goto out;
 734         }
 735
 736         restart = &current_thread_info()->restart_block;
 737         restart->fn = alarm_timer_nsleep_restart;
 738         restart->nanosleep.clockid = type;
 739         restart->nanosleep.expires = exp.tv64;
 740         restart->nanosleep.rmtp = rmtp;
 741         ret = -ERESTART_RESTARTBLOCK;
 742
 743 out:
 744         return ret;
 745 }
 746
 747
 748 /* Suspend hook structures */
 749 static const struct dev_pm_ops alarmtimer_pm_ops = {
 750         .suspend = alarmtimer_suspend,
 751 };
 752
 753 static struct platform_driver alarmtimer_driver = {
 754         .driver = {
 755                 .name = "alarmtimer",
 756                 .pm = &alarmtimer_pm_ops,
 757         }
 758 };
 759
 760 /**
 761  * alarmtimer_init - Initialize alarm timer code
 762  *
 763  * This function initializes the alarm bases and registers
 764  * the posix clock ids.
 765  */
 766 static int __init alarmtimer_init(void)
 767 {
 768         struct platform_device *pdev;
 769         int error = 0;
 770         int i;
 771         struct k_clock alarm_clock = {
 772                 .clock_getres   = alarm_clock_getres,
 773                 .clock_get      = alarm_clock_get,
 774                 .timer_create   = alarm_timer_create,
 775                 .timer_set      = alarm_timer_set,
 776                 .timer_del      = alarm_timer_del,
 777                 .timer_get      = alarm_timer_get,
 778                 .nsleep         = alarm_timer_nsleep,
 779         };
 780
 781         alarmtimer_rtc_timer_init();
 782
 783         posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
 784         posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
 785
 786         /* Initialize alarm bases */
 787         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 788         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
 789         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 790         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
 791         for (i = 0; i < ALARM_NUMTYPE; i++) {
 792                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 793                 spin_lock_init(&alarm_bases[i].lock);
 794         }
 795
 796         error = alarmtimer_rtc_interface_setup();
 797         if (error)
 798                 return error;
 799
 800         error = platform_driver_register(&alarmtimer_driver);
 801         if (error)
 802                 goto out_if;
 803
 804         pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
 805         if (IS_ERR(pdev)) {
 806                 error = PTR_ERR(pdev);
 807                 goto out_drv;
 808         }
 809         ws = wakeup_source_register("alarmtimer");
 810         return 0;
 811
 812 out_drv:
 813         platform_driver_unregister(&alarmtimer_driver);
 814 out_if:
 815         alarmtimer_rtc_interface_remove();
 816         return error;
 817 }
 818 device_initcall(alarmtimer_init);