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/sched/signal.h>
  23 #include <linux/sched/debug.h>
  24 #include <linux/alarmtimer.h>
  25 #include <linux/mutex.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/posix-timers.h>
  28 #include <linux/workqueue.h>
  29 #include <linux/freezer.h>
  30
  31 #define CREATE_TRACE_POINTS
  32 #include <trace/events/alarmtimer.h>
  33
  34 /**
  35  * struct alarm_base - Alarm timer bases
  36  * @lock:               Lock for syncrhonized access to the base
  37  * @timerqueue:         Timerqueue head managing the list of events
  38  * @gettime:            Function to read the time correlating to the base
  39  * @base_clockid:       clockid for the base
  40  */
  41 static struct alarm_base {
  42         spinlock_t              lock;
  43         struct timerqueue_head  timerqueue;
  44         ktime_t                 (*gettime)(void);
  45         clockid_t               base_clockid;
  46 } alarm_bases[ALARM_NUMTYPE];
  47
  48 /* freezer information to handle clock_nanosleep triggered wakeups */
  49 static enum alarmtimer_type freezer_alarmtype;
  50 static ktime_t freezer_expires;
  51 static ktime_t freezer_delta;
  52 static DEFINE_SPINLOCK(freezer_delta_lock);
  53
  54 static struct wakeup_source *ws;
  55
  56 #ifdef CONFIG_RTC_CLASS
  57 /* rtc timer and device for setting alarm wakeups at suspend */
  58 static struct rtc_timer         rtctimer;
  59 static struct rtc_device        *rtcdev;
  60 static DEFINE_SPINLOCK(rtcdev_lock);
  61
  62 /**
  63  * alarmtimer_get_rtcdev - Return selected rtcdevice
  64  *
  65  * This function returns the rtc device to use for wakealarms.
  66  * If one has not already been chosen, it checks to see if a
  67  * functional rtc device is available.
  68  */
  69 struct rtc_device *alarmtimer_get_rtcdev(void)
  70 {
  71         unsigned long flags;
  72         struct rtc_device *ret;
  73
  74         spin_lock_irqsave(&rtcdev_lock, flags);
  75         ret = rtcdev;
  76         spin_unlock_irqrestore(&rtcdev_lock, flags);
  77
  78         return ret;
  79 }
  80 EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
  81
  82 static int alarmtimer_rtc_add_device(struct device *dev,
  83                                 struct class_interface *class_intf)
  84 {
  85         unsigned long flags;
  86         struct rtc_device *rtc = to_rtc_device(dev);
  87
  88         if (rtcdev)
  89                 return -EBUSY;
  90
  91         if (!rtc->ops->set_alarm)
  92                 return -1;
  93         if (!device_may_wakeup(rtc->dev.parent))
  94                 return -1;
  95
  96         spin_lock_irqsave(&rtcdev_lock, flags);
  97         if (!rtcdev) {
  98                 rtcdev = rtc;
  99                 /* hold a reference so it doesn't go away */
 100                 get_device(dev);
 101         }
 102         spin_unlock_irqrestore(&rtcdev_lock, flags);
 103         return 0;
 104 }
 105
 106 static inline void alarmtimer_rtc_timer_init(void)
 107 {
 108         rtc_timer_init(&rtctimer, NULL, NULL);
 109 }
 110
 111 static struct class_interface alarmtimer_rtc_interface = {
 112         .add_dev = &alarmtimer_rtc_add_device,
 113 };
 114
 115 static int alarmtimer_rtc_interface_setup(void)
 116 {
 117         alarmtimer_rtc_interface.class = rtc_class;
 118         return class_interface_register(&alarmtimer_rtc_interface);
 119 }
 120 static void alarmtimer_rtc_interface_remove(void)
 121 {
 122         class_interface_unregister(&alarmtimer_rtc_interface);
 123 }
 124 #else
 125 struct rtc_device *alarmtimer_get_rtcdev(void)
 126 {
 127         return NULL;
 128 }
 129 #define rtcdev (NULL)
 130 static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
 131 static inline void alarmtimer_rtc_interface_remove(void) { }
 132 static inline void alarmtimer_rtc_timer_init(void) { }
 133 #endif
 134
 135 /**
 136  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
 137  * @base: pointer to the base where the timer is being run
 138  * @alarm: pointer to alarm being enqueued.
 139  *
 140  * Adds alarm to a alarm_base timerqueue
 141  *
 142  * Must hold base->lock when calling.
 143  */
 144 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
 145 {
 146         if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
 147                 timerqueue_del(&base->timerqueue, &alarm->node);
 148
 149         timerqueue_add(&base->timerqueue, &alarm->node);
 150         alarm->state |= ALARMTIMER_STATE_ENQUEUED;
 151 }
 152
 153 /**
 154  * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
 155  * @base: pointer to the base where the timer is running
 156  * @alarm: pointer to alarm being removed
 157  *
 158  * Removes alarm to a alarm_base timerqueue
 159  *
 160  * Must hold base->lock when calling.
 161  */
 162 static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
 163 {
 164         if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
 165                 return;
 166
 167         timerqueue_del(&base->timerqueue, &alarm->node);
 168         alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
 169 }
 170
 171
 172 /**
 173  * alarmtimer_fired - Handles alarm hrtimer being fired.
 174  * @timer: pointer to hrtimer being run
 175  *
 176  * When a alarm timer fires, this runs through the timerqueue to
 177  * see which alarms expired, and runs those. If there are more alarm
 178  * timers queued for the future, we set the hrtimer to fire when
 179  * when the next future alarm timer expires.
 180  */
 181 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 182 {
 183         struct alarm *alarm = container_of(timer, struct alarm, timer);
 184         struct alarm_base *base = &alarm_bases[alarm->type];
 185         unsigned long flags;
 186         int ret = HRTIMER_NORESTART;
 187         int restart = ALARMTIMER_NORESTART;
 188
 189         spin_lock_irqsave(&base->lock, flags);
 190         alarmtimer_dequeue(base, alarm);
 191         spin_unlock_irqrestore(&base->lock, flags);
 192
 193         if (alarm->function)
 194                 restart = alarm->function(alarm, base->gettime());
 195
 196         spin_lock_irqsave(&base->lock, flags);
 197         if (restart != ALARMTIMER_NORESTART) {
 198                 hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 199                 alarmtimer_enqueue(base, alarm);
 200                 ret = HRTIMER_RESTART;
 201         }
 202         spin_unlock_irqrestore(&base->lock, flags);
 203
 204         trace_alarmtimer_fired(alarm, base->gettime());
 205         return ret;
 206
 207 }
 208
 209 ktime_t alarm_expires_remaining(const struct alarm *alarm)
 210 {
 211         struct alarm_base *base = &alarm_bases[alarm->type];
 212         return ktime_sub(alarm->node.expires, base->gettime());
 213 }
 214 EXPORT_SYMBOL_GPL(alarm_expires_remaining);
 215
 216 #ifdef CONFIG_RTC_CLASS
 217 /**
 218  * alarmtimer_suspend - Suspend time callback
 219  * @dev: unused
 220  * @state: unused
 221  *
 222  * When we are going into suspend, we look through the bases
 223  * to see which is the soonest timer to expire. We then
 224  * set an rtc timer to fire that far into the future, which
 225  * will wake us from suspend.
 226  */
 227 static int alarmtimer_suspend(struct device *dev)
 228 {
 229         ktime_t min, now, expires;
 230         int i, ret, type;
 231         struct rtc_device *rtc;
 232         unsigned long flags;
 233         struct rtc_time tm;
 234
 235         spin_lock_irqsave(&freezer_delta_lock, flags);
 236         min = freezer_delta;
 237         expires = freezer_expires;
 238         type = freezer_alarmtype;
 239         freezer_delta = 0;
 240         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 241
 242         rtc = alarmtimer_get_rtcdev();
 243         /* If we have no rtcdev, just return */
 244         if (!rtc)
 245                 return 0;
 246
 247         /* Find the soonest timer to expire*/
 248         for (i = 0; i < ALARM_NUMTYPE; i++) {
 249                 struct alarm_base *base = &alarm_bases[i];
 250                 struct timerqueue_node *next;
 251                 ktime_t delta;
 252
 253                 spin_lock_irqsave(&base->lock, flags);
 254                 next = timerqueue_getnext(&base->timerqueue);
 255                 spin_unlock_irqrestore(&base->lock, flags);
 256                 if (!next)
 257                         continue;
 258                 delta = ktime_sub(next->expires, base->gettime());
 259                 if (!min || (delta < min)) {
 260                         expires = next->expires;
 261                         min = delta;
 262                         type = i;
 263                 }
 264         }
 265         if (min == 0)
 266                 return 0;
 267
 268         if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
 269                 __pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
 270                 return -EBUSY;
 271         }
 272
 273         trace_alarmtimer_suspend(expires, type);
 274
 275         /* Setup an rtc timer to fire that far in the future */
 276         rtc_timer_cancel(rtc, &rtctimer);
 277         rtc_read_time(rtc, &tm);
 278         now = rtc_tm_to_ktime(tm);
 279         now = ktime_add(now, min);
 280
 281         /* Set alarm, if in the past reject suspend briefly to handle */
 282         ret = rtc_timer_start(rtc, &rtctimer, now, 0);
 283         if (ret < 0)
 284                 __pm_wakeup_event(ws, MSEC_PER_SEC);
 285         return ret;
 286 }
 287
 288 static int alarmtimer_resume(struct device *dev)
 289 {
 290         struct rtc_device *rtc;
 291
 292         rtc = alarmtimer_get_rtcdev();
 293         if (rtc)
 294                 rtc_timer_cancel(rtc, &rtctimer);
 295         return 0;
 296 }
 297
 298 #else
 299 static int alarmtimer_suspend(struct device *dev)
 300 {
 301         return 0;
 302 }
 303
 304 static int alarmtimer_resume(struct device *dev)
 305 {
 306         return 0;
 307 }
 308 #endif
 309
 310 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 311 {
 312         struct alarm_base *base;
 313         unsigned long flags;
 314         ktime_t delta;
 315
 316         switch(type) {
 317         case ALARM_REALTIME:
 318                 base = &alarm_bases[ALARM_REALTIME];
 319                 type = ALARM_REALTIME_FREEZER;
 320                 break;
 321         case ALARM_BOOTTIME:
 322                 base = &alarm_bases[ALARM_BOOTTIME];
 323                 type = ALARM_BOOTTIME_FREEZER;
 324                 break;
 325         default:
 326                 WARN_ONCE(1, "Invalid alarm type: %d\n", type);
 327                 return;
 328         }
 329
 330         delta = ktime_sub(absexp, base->gettime());
 331
 332         spin_lock_irqsave(&freezer_delta_lock, flags);
 333         if (!freezer_delta || (delta < freezer_delta)) {
 334                 freezer_delta = delta;
 335                 freezer_expires = absexp;
 336                 freezer_alarmtype = type;
 337         }
 338         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 339 }
 340
 341
 342 /**
 343  * alarm_init - Initialize an alarm structure
 344  * @alarm: ptr to alarm to be initialized
 345  * @type: the type of the alarm
 346  * @function: callback that is run when the alarm fires
 347  */
 348 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 349                 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 350 {
 351         timerqueue_init(&alarm->node);
 352         hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
 353                         HRTIMER_MODE_ABS);
 354         alarm->timer.function = alarmtimer_fired;
 355         alarm->function = function;
 356         alarm->type = type;
 357         alarm->state = ALARMTIMER_STATE_INACTIVE;
 358 }
 359 EXPORT_SYMBOL_GPL(alarm_init);
 360
 361 /**
 362  * alarm_start - Sets an absolute alarm to fire
 363  * @alarm: ptr to alarm to set
 364  * @start: time to run the alarm
 365  */
 366 void alarm_start(struct alarm *alarm, ktime_t start)
 367 {
 368         struct alarm_base *base = &alarm_bases[alarm->type];
 369         unsigned long flags;
 370
 371         spin_lock_irqsave(&base->lock, flags);
 372         alarm->node.expires = start;
 373         alarmtimer_enqueue(base, alarm);
 374         hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
 375         spin_unlock_irqrestore(&base->lock, flags);
 376
 377         trace_alarmtimer_start(alarm, base->gettime());
 378 }
 379 EXPORT_SYMBOL_GPL(alarm_start);
 380
 381 /**
 382  * alarm_start_relative - Sets a relative alarm to fire
 383  * @alarm: ptr to alarm to set
 384  * @start: time relative to now to run the alarm
 385  */
 386 void alarm_start_relative(struct alarm *alarm, ktime_t start)
 387 {
 388         struct alarm_base *base = &alarm_bases[alarm->type];
 389
 390         start = ktime_add(start, base->gettime());
 391         alarm_start(alarm, start);
 392 }
 393 EXPORT_SYMBOL_GPL(alarm_start_relative);
 394
 395 void alarm_restart(struct alarm *alarm)
 396 {
 397         struct alarm_base *base = &alarm_bases[alarm->type];
 398         unsigned long flags;
 399
 400         spin_lock_irqsave(&base->lock, flags);
 401         hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 402         hrtimer_restart(&alarm->timer);
 403         alarmtimer_enqueue(base, alarm);
 404         spin_unlock_irqrestore(&base->lock, flags);
 405 }
 406 EXPORT_SYMBOL_GPL(alarm_restart);
 407
 408 /**
 409  * alarm_try_to_cancel - Tries to cancel an alarm timer
 410  * @alarm: ptr to alarm to be canceled
 411  *
 412  * Returns 1 if the timer was canceled, 0 if it was not running,
 413  * and -1 if the callback was running
 414  */
 415 int alarm_try_to_cancel(struct alarm *alarm)
 416 {
 417         struct alarm_base *base = &alarm_bases[alarm->type];
 418         unsigned long flags;
 419         int ret;
 420
 421         spin_lock_irqsave(&base->lock, flags);
 422         ret = hrtimer_try_to_cancel(&alarm->timer);
 423         if (ret >= 0)
 424                 alarmtimer_dequeue(base, alarm);
 425         spin_unlock_irqrestore(&base->lock, flags);
 426
 427         trace_alarmtimer_cancel(alarm, base->gettime());
 428         return ret;
 429 }
 430 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
 431
 432
 433 /**
 434  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
 435  * @alarm: ptr to alarm to be canceled
 436  *
 437  * Returns 1 if the timer was canceled, 0 if it was not active.
 438  */
 439 int alarm_cancel(struct alarm *alarm)
 440 {
 441         for (;;) {
 442                 int ret = alarm_try_to_cancel(alarm);
 443                 if (ret >= 0)
 444                         return ret;
 445                 cpu_relax();
 446         }
 447 }
 448 EXPORT_SYMBOL_GPL(alarm_cancel);
 449
 450
 451 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
 452 {
 453         u64 overrun = 1;
 454         ktime_t delta;
 455
 456         delta = ktime_sub(now, alarm->node.expires);
 457
 458         if (delta < 0)
 459                 return 0;
 460
 461         if (unlikely(delta >= interval)) {
 462                 s64 incr = ktime_to_ns(interval);
 463
 464                 overrun = ktime_divns(delta, incr);
 465
 466                 alarm->node.expires = ktime_add_ns(alarm->node.expires,
 467                                                         incr*overrun);
 468
 469                 if (alarm->node.expires > now)
 470                         return overrun;
 471                 /*
 472                  * This (and the ktime_add() below) is the
 473                  * correction for exact:
 474                  */
 475                 overrun++;
 476         }
 477
 478         alarm->node.expires = ktime_add(alarm->node.expires, interval);
 479         return overrun;
 480 }
 481 EXPORT_SYMBOL_GPL(alarm_forward);
 482
 483 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 484 {
 485         struct alarm_base *base = &alarm_bases[alarm->type];
 486
 487         return alarm_forward(alarm, base->gettime(), interval);
 488 }
 489 EXPORT_SYMBOL_GPL(alarm_forward_now);
 490
 491
 492 /**
 493  * clock2alarm - helper that converts from clockid to alarmtypes
 494  * @clockid: clockid.
 495  */
 496 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 497 {
 498         if (clockid == CLOCK_REALTIME_ALARM)
 499                 return ALARM_REALTIME;
 500         if (clockid == CLOCK_BOOTTIME_ALARM)
 501                 return ALARM_BOOTTIME;
 502         return -1;
 503 }
 504
 505 /**
 506  * alarm_handle_timer - Callback for posix timers
 507  * @alarm: alarm that fired
 508  *
 509  * Posix timer callback for expired alarm timers.
 510  */
 511 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 512                                                         ktime_t now)
 513 {
 514         unsigned long flags;
 515         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 516                                                 it.alarm.alarmtimer);
 517         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
 518
 519         spin_lock_irqsave(&ptr->it_lock, flags);
 520         if ((ptr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) {
 521                 if (IS_ENABLED(CONFIG_POSIX_TIMERS) &&
 522                     posix_timer_event(ptr, 0) != 0)
 523                         ptr->it_overrun++;
 524         }
 525
 526         /* Re-add periodic timers */
 527         if (ptr->it.alarm.interval) {
 528                 ptr->it_overrun += alarm_forward(alarm, now,
 529                                                 ptr->it.alarm.interval);
 530                 result = ALARMTIMER_RESTART;
 531         }
 532         spin_unlock_irqrestore(&ptr->it_lock, flags);
 533
 534         return result;
 535 }
 536
 537 /**
 538  * alarm_clock_getres - posix getres interface
 539  * @which_clock: clockid
 540  * @tp: timespec to fill
 541  *
 542  * Returns the granularity of underlying alarm base clock
 543  */
 544 static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 545 {
 546         if (!alarmtimer_get_rtcdev())
 547                 return -EINVAL;
 548
 549         tp->tv_sec = 0;
 550         tp->tv_nsec = hrtimer_resolution;
 551         return 0;
 552 }
 553
 554 /**
 555  * alarm_clock_get - posix clock_get interface
 556  * @which_clock: clockid
 557  * @tp: timespec to fill.
 558  *
 559  * Provides the underlying alarm base time.
 560  */
 561 static int alarm_clock_get(clockid_t which_clock, struct timespec64 *tp)
 562 {
 563         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 564
 565         if (!alarmtimer_get_rtcdev())
 566                 return -EINVAL;
 567
 568         *tp = ktime_to_timespec64(base->gettime());
 569         return 0;
 570 }
 571
 572 /**
 573  * alarm_timer_create - posix timer_create interface
 574  * @new_timer: k_itimer pointer to manage
 575  *
 576  * Initializes the k_itimer structure.
 577  */
 578 static int alarm_timer_create(struct k_itimer *new_timer)
 579 {
 580         enum  alarmtimer_type type;
 581
 582         if (!alarmtimer_get_rtcdev())
 583                 return -ENOTSUPP;
 584
 585         if (!capable(CAP_WAKE_ALARM))
 586                 return -EPERM;
 587
 588         type = clock2alarm(new_timer->it_clock);
 589         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 590         return 0;
 591 }
 592
 593 /**
 594  * alarm_timer_get - posix timer_get interface
 595  * @new_timer: k_itimer pointer
 596  * @cur_setting: itimerspec data to fill
 597  *
 598  * Copies out the current itimerspec data
 599  */
 600 static void alarm_timer_get(struct k_itimer *timr,
 601                             struct itimerspec64 *cur_setting)
 602 {
 603         ktime_t relative_expiry_time =
 604                 alarm_expires_remaining(&(timr->it.alarm.alarmtimer));
 605
 606         if (ktime_to_ns(relative_expiry_time) > 0) {
 607                 cur_setting->it_value = ktime_to_timespec64(relative_expiry_time);
 608         } else {
 609                 cur_setting->it_value.tv_sec = 0;
 610                 cur_setting->it_value.tv_nsec = 0;
 611         }
 612
 613         cur_setting->it_interval = ktime_to_timespec64(timr->it.alarm.interval);
 614 }
 615
 616 /**
 617  * alarm_timer_del - posix timer_del interface
 618  * @timr: k_itimer pointer to be deleted
 619  *
 620  * Cancels any programmed alarms for the given timer.
 621  */
 622 static int alarm_timer_del(struct k_itimer *timr)
 623 {
 624         if (!rtcdev)
 625                 return -ENOTSUPP;
 626
 627         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 628                 return TIMER_RETRY;
 629
 630         return 0;
 631 }
 632
 633 /**
 634  * alarm_timer_set - posix timer_set interface
 635  * @timr: k_itimer pointer to be deleted
 636  * @flags: timer flags
 637  * @new_setting: itimerspec to be used
 638  * @old_setting: itimerspec being replaced
 639  *
 640  * Sets the timer to new_setting, and starts the timer.
 641  */
 642 static int alarm_timer_set(struct k_itimer *timr, int flags,
 643                            struct itimerspec64 *new_setting,
 644                            struct itimerspec64 *old_setting)
 645 {
 646         ktime_t exp;
 647
 648         if (!rtcdev)
 649                 return -ENOTSUPP;
 650
 651         if (flags & ~TIMER_ABSTIME)
 652                 return -EINVAL;
 653
 654         if (old_setting)
 655                 alarm_timer_get(timr, old_setting);
 656
 657         /* If the timer was already set, cancel it */
 658         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
 659                 return TIMER_RETRY;
 660
 661         /* start the timer */
 662         timr->it.alarm.interval = timespec64_to_ktime(new_setting->it_interval);
 663         exp = timespec64_to_ktime(new_setting->it_value);
 664         /* Convert (if necessary) to absolute time */
 665         if (flags != TIMER_ABSTIME) {
 666                 ktime_t now;
 667
 668                 now = alarm_bases[timr->it.alarm.alarmtimer.type].gettime();
 669                 exp = ktime_add(now, exp);
 670         }
 671
 672         alarm_start(&timr->it.alarm.alarmtimer, exp);
 673         return 0;
 674 }
 675
 676 /**
 677  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 678  * @alarm: ptr to alarm that fired
 679  *
 680  * Wakes up the task that set the alarmtimer
 681  */
 682 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 683                                                                 ktime_t now)
 684 {
 685         struct task_struct *task = (struct task_struct *)alarm->data;
 686
 687         alarm->data = NULL;
 688         if (task)
 689                 wake_up_process(task);
 690         return ALARMTIMER_NORESTART;
 691 }
 692
 693 /**
 694  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 695  * @alarm: ptr to alarmtimer
 696  * @absexp: absolute expiration time
 697  *
 698  * Sets the alarm timer and sleeps until it is fired or interrupted.
 699  */
 700 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
 701 {
 702         alarm->data = (void *)current;
 703         do {
 704                 set_current_state(TASK_INTERRUPTIBLE);
 705                 alarm_start(alarm, absexp);
 706                 if (likely(alarm->data))
 707                         schedule();
 708
 709                 alarm_cancel(alarm);
 710         } while (alarm->data && !signal_pending(current));
 711
 712         __set_current_state(TASK_RUNNING);
 713
 714         return (alarm->data == NULL);
 715 }
 716
 717
 718 /**
 719  * update_rmtp - Update remaining timespec value
 720  * @exp: expiration time
 721  * @type: timer type
 722  * @rmtp: user pointer to remaining timepsec value
 723  *
 724  * Helper function that fills in rmtp value with time between
 725  * now and the exp value
 726  */
 727 static int update_rmtp(ktime_t exp, enum  alarmtimer_type type,
 728                         struct timespec __user *rmtp)
 729 {
 730         struct timespec rmt;
 731         ktime_t rem;
 732
 733         rem = ktime_sub(exp, alarm_bases[type].gettime());
 734
 735         if (rem <= 0)
 736                 return 0;
 737         rmt = ktime_to_timespec(rem);
 738
 739         if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
 740                 return -EFAULT;
 741
 742         return 1;
 743
 744 }
 745
 746 /**
 747  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 748  * @restart: ptr to restart block
 749  *
 750  * Handles restarted clock_nanosleep calls
 751  */
 752 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 753 {
 754         enum  alarmtimer_type type = restart->nanosleep.clockid;
 755         ktime_t exp;
 756         struct timespec __user  *rmtp;
 757         struct alarm alarm;
 758         int ret = 0;
 759
 760         exp = restart->nanosleep.expires;
 761         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 762
 763         if (alarmtimer_do_nsleep(&alarm, exp))
 764                 goto out;
 765
 766         if (freezing(current))
 767                 alarmtimer_freezerset(exp, type);
 768
 769         rmtp = restart->nanosleep.rmtp;
 770         if (rmtp) {
 771                 ret = update_rmtp(exp, type, rmtp);
 772                 if (ret <= 0)
 773                         goto out;
 774         }
 775
 776
 777         /* The other values in restart are already filled in */
 778         ret = -ERESTART_RESTARTBLOCK;
 779 out:
 780         return ret;
 781 }
 782
 783 /**
 784  * alarm_timer_nsleep - alarmtimer nanosleep
 785  * @which_clock: clockid
 786  * @flags: determins abstime or relative
 787  * @tsreq: requested sleep time (abs or rel)
 788  * @rmtp: remaining sleep time saved
 789  *
 790  * Handles clock_nanosleep calls against _ALARM clockids
 791  */
 792 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 793                               struct timespec64 *tsreq,
 794                               struct timespec __user *rmtp)
 795 {
 796         enum  alarmtimer_type type = clock2alarm(which_clock);
 797         struct restart_block *restart;
 798         struct alarm alarm;
 799         ktime_t exp;
 800         int ret = 0;
 801
 802         if (!alarmtimer_get_rtcdev())
 803                 return -ENOTSUPP;
 804
 805         if (flags & ~TIMER_ABSTIME)
 806                 return -EINVAL;
 807
 808         if (!capable(CAP_WAKE_ALARM))
 809                 return -EPERM;
 810
 811         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
 812
 813         exp = timespec64_to_ktime(*tsreq);
 814         /* Convert (if necessary) to absolute time */
 815         if (flags != TIMER_ABSTIME) {
 816                 ktime_t now = alarm_bases[type].gettime();
 817                 exp = ktime_add(now, exp);
 818         }
 819
 820         if (alarmtimer_do_nsleep(&alarm, exp))
 821                 goto out;
 822
 823         if (freezing(current))
 824                 alarmtimer_freezerset(exp, type);
 825
 826         /* abs timers don't set remaining time or restart */
 827         if (flags == TIMER_ABSTIME) {
 828                 ret = -ERESTARTNOHAND;
 829                 goto out;
 830         }
 831
 832         if (rmtp) {
 833                 ret = update_rmtp(exp, type, rmtp);
 834                 if (ret <= 0)
 835                         goto out;
 836         }
 837
 838         restart = &current->restart_block;
 839         restart->fn = alarm_timer_nsleep_restart;
 840         restart->nanosleep.clockid = type;
 841         restart->nanosleep.expires = exp;
 842         restart->nanosleep.rmtp = rmtp;
 843         ret = -ERESTART_RESTARTBLOCK;
 844
 845 out:
 846         return ret;
 847 }
 848
 849
 850 /* Suspend hook structures */
 851 static const struct dev_pm_ops alarmtimer_pm_ops = {
 852         .suspend = alarmtimer_suspend,
 853         .resume = alarmtimer_resume,
 854 };
 855
 856 static struct platform_driver alarmtimer_driver = {
 857         .driver = {
 858                 .name = "alarmtimer",
 859                 .pm = &alarmtimer_pm_ops,
 860         }
 861 };
 862
 863 /**
 864  * alarmtimer_init - Initialize alarm timer code
 865  *
 866  * This function initializes the alarm bases and registers
 867  * the posix clock ids.
 868  */
 869 static int __init alarmtimer_init(void)
 870 {
 871         struct platform_device *pdev;
 872         int error = 0;
 873         int i;
 874         struct k_clock alarm_clock = {
 875                 .clock_getres   = alarm_clock_getres,
 876                 .clock_get      = alarm_clock_get,
 877                 .timer_create   = alarm_timer_create,
 878                 .timer_set      = alarm_timer_set,
 879                 .timer_del      = alarm_timer_del,
 880                 .timer_get      = alarm_timer_get,
 881                 .nsleep         = alarm_timer_nsleep,
 882         };
 883
 884         alarmtimer_rtc_timer_init();
 885
 886         if (IS_ENABLED(CONFIG_POSIX_TIMERS)) {
 887                 posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
 888                 posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
 889         }
 890
 891         /* Initialize alarm bases */
 892         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 893         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
 894         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 895         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
 896         for (i = 0; i < ALARM_NUMTYPE; i++) {
 897                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 898                 spin_lock_init(&alarm_bases[i].lock);
 899         }
 900
 901         error = alarmtimer_rtc_interface_setup();
 902         if (error)
 903                 return error;
 904
 905         error = platform_driver_register(&alarmtimer_driver);
 906         if (error)
 907                 goto out_if;
 908
 909         pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
 910         if (IS_ERR(pdev)) {
 911                 error = PTR_ERR(pdev);
 912                 goto out_drv;
 913         }
 914         ws = wakeup_source_register("alarmtimer");
 915         return 0;
 916
 917 out_drv:
 918         platform_driver_unregister(&alarmtimer_driver);
 919 out_if:
 920         alarmtimer_rtc_interface_remove();
 921         return error;
 922 }
 923 device_initcall(alarmtimer_init);