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