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 #include <linux/compat.h>
  31 #include <linux/module.h>
  32
  33 #include "posix-timers.h"
  34
  35 #define CREATE_TRACE_POINTS
  36 #include <trace/events/alarmtimer.h>
  37
  38 /**
  39  * struct alarm_base - Alarm timer bases
  40  * @lock:               Lock for syncrhonized access to the base
  41  * @timerqueue:         Timerqueue head managing the list of events
  42  * @gettime:            Function to read the time correlating to the base
  43  * @base_clockid:       clockid for the base
  44  */
  45 static struct alarm_base {
  46         spinlock_t              lock;
  47         struct timerqueue_head  timerqueue;
  48         ktime_t                 (*gettime)(void);
  49         clockid_t               base_clockid;
  50 } alarm_bases[ALARM_NUMTYPE];
  51
  52 #if defined(CONFIG_POSIX_TIMERS) || defined(CONFIG_RTC_CLASS)
  53 /* freezer information to handle clock_nanosleep triggered wakeups */
  54 static enum alarmtimer_type freezer_alarmtype;
  55 static ktime_t freezer_expires;
  56 static ktime_t freezer_delta;
  57 static DEFINE_SPINLOCK(freezer_delta_lock);
  58 #endif
  59
  60 #ifdef CONFIG_RTC_CLASS
  61 static struct wakeup_source *ws;
  62
  63 /* rtc timer and device for setting alarm wakeups at suspend */
  64 static struct rtc_timer         rtctimer;
  65 static struct rtc_device        *rtcdev;
  66 static DEFINE_SPINLOCK(rtcdev_lock);
  67
  68 /**
  69  * alarmtimer_get_rtcdev - Return selected rtcdevice
  70  *
  71  * This function returns the rtc device to use for wakealarms.
  72  * If one has not already been chosen, it checks to see if a
  73  * functional rtc device is available.
  74  */
  75 struct rtc_device *alarmtimer_get_rtcdev(void)
  76 {
  77         unsigned long flags;
  78         struct rtc_device *ret;
  79
  80         spin_lock_irqsave(&rtcdev_lock, flags);
  81         ret = rtcdev;
  82         spin_unlock_irqrestore(&rtcdev_lock, flags);
  83
  84         return ret;
  85 }
  86 EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
  87
  88 static int alarmtimer_rtc_add_device(struct device *dev,
  89                                 struct class_interface *class_intf)
  90 {
  91         unsigned long flags;
  92         struct rtc_device *rtc = to_rtc_device(dev);
  93         struct wakeup_source *__ws;
  94         int ret = 0;
  95
  96         if (rtcdev)
  97                 return -EBUSY;
  98
  99         if (!rtc->ops->set_alarm)
 100                 return -1;
 101         if (!device_may_wakeup(rtc->dev.parent))
 102                 return -1;
 103
 104         __ws = wakeup_source_register("alarmtimer");
 105
 106         spin_lock_irqsave(&rtcdev_lock, flags);
 107         if (!rtcdev) {
 108                 if (!try_module_get(rtc->owner)) {
 109                         ret = -1;
 110                         goto unlock;
 111                 }
 112
 113                 rtcdev = rtc;
 114                 /* hold a reference so it doesn't go away */
 115                 get_device(dev);
 116                 ws = __ws;
 117                 __ws = NULL;
 118         }
 119 unlock:
 120         spin_unlock_irqrestore(&rtcdev_lock, flags);
 121
 122         wakeup_source_unregister(__ws);
 123
 124         return ret;
 125 }
 126
 127 static inline void alarmtimer_rtc_timer_init(void)
 128 {
 129         rtc_timer_init(&rtctimer, NULL, NULL);
 130 }
 131
 132 static struct class_interface alarmtimer_rtc_interface = {
 133         .add_dev = &alarmtimer_rtc_add_device,
 134 };
 135
 136 static int alarmtimer_rtc_interface_setup(void)
 137 {
 138         alarmtimer_rtc_interface.class = rtc_class;
 139         return class_interface_register(&alarmtimer_rtc_interface);
 140 }
 141 static void alarmtimer_rtc_interface_remove(void)
 142 {
 143         class_interface_unregister(&alarmtimer_rtc_interface);
 144 }
 145 #else
 146 struct rtc_device *alarmtimer_get_rtcdev(void)
 147 {
 148         return NULL;
 149 }
 150 #define rtcdev (NULL)
 151 static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
 152 static inline void alarmtimer_rtc_interface_remove(void) { }
 153 static inline void alarmtimer_rtc_timer_init(void) { }
 154 #endif
 155
 156 /**
 157  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
 158  * @base: pointer to the base where the timer is being run
 159  * @alarm: pointer to alarm being enqueued.
 160  *
 161  * Adds alarm to a alarm_base timerqueue
 162  *
 163  * Must hold base->lock when calling.
 164  */
 165 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
 166 {
 167         if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
 168                 timerqueue_del(&base->timerqueue, &alarm->node);
 169
 170         timerqueue_add(&base->timerqueue, &alarm->node);
 171         alarm->state |= ALARMTIMER_STATE_ENQUEUED;
 172 }
 173
 174 /**
 175  * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
 176  * @base: pointer to the base where the timer is running
 177  * @alarm: pointer to alarm being removed
 178  *
 179  * Removes alarm to a alarm_base timerqueue
 180  *
 181  * Must hold base->lock when calling.
 182  */
 183 static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
 184 {
 185         if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
 186                 return;
 187
 188         timerqueue_del(&base->timerqueue, &alarm->node);
 189         alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
 190 }
 191
 192
 193 /**
 194  * alarmtimer_fired - Handles alarm hrtimer being fired.
 195  * @timer: pointer to hrtimer being run
 196  *
 197  * When a alarm timer fires, this runs through the timerqueue to
 198  * see which alarms expired, and runs those. If there are more alarm
 199  * timers queued for the future, we set the hrtimer to fire when
 200  * when the next future alarm timer expires.
 201  */
 202 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 203 {
 204         struct alarm *alarm = container_of(timer, struct alarm, timer);
 205         struct alarm_base *base = &alarm_bases[alarm->type];
 206         unsigned long flags;
 207         int ret = HRTIMER_NORESTART;
 208         int restart = ALARMTIMER_NORESTART;
 209
 210         spin_lock_irqsave(&base->lock, flags);
 211         alarmtimer_dequeue(base, alarm);
 212         spin_unlock_irqrestore(&base->lock, flags);
 213
 214         if (alarm->function)
 215                 restart = alarm->function(alarm, base->gettime());
 216
 217         spin_lock_irqsave(&base->lock, flags);
 218         if (restart != ALARMTIMER_NORESTART) {
 219                 hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 220                 alarmtimer_enqueue(base, alarm);
 221                 ret = HRTIMER_RESTART;
 222         }
 223         spin_unlock_irqrestore(&base->lock, flags);
 224
 225         trace_alarmtimer_fired(alarm, base->gettime());
 226         return ret;
 227
 228 }
 229
 230 ktime_t alarm_expires_remaining(const struct alarm *alarm)
 231 {
 232         struct alarm_base *base = &alarm_bases[alarm->type];
 233         return ktime_sub(alarm->node.expires, base->gettime());
 234 }
 235 EXPORT_SYMBOL_GPL(alarm_expires_remaining);
 236
 237 #ifdef CONFIG_RTC_CLASS
 238 /**
 239  * alarmtimer_suspend - Suspend time callback
 240  * @dev: unused
 241  * @state: unused
 242  *
 243  * When we are going into suspend, we look through the bases
 244  * to see which is the soonest timer to expire. We then
 245  * set an rtc timer to fire that far into the future, which
 246  * will wake us from suspend.
 247  */
 248 static int alarmtimer_suspend(struct device *dev)
 249 {
 250         ktime_t min, now, expires;
 251         int i, ret, type;
 252         struct rtc_device *rtc;
 253         unsigned long flags;
 254         struct rtc_time tm;
 255
 256         spin_lock_irqsave(&freezer_delta_lock, flags);
 257         min = freezer_delta;
 258         expires = freezer_expires;
 259         type = freezer_alarmtype;
 260         freezer_delta = 0;
 261         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 262
 263         rtc = alarmtimer_get_rtcdev();
 264         /* If we have no rtcdev, just return */
 265         if (!rtc)
 266                 return 0;
 267
 268         /* Find the soonest timer to expire*/
 269         for (i = 0; i < ALARM_NUMTYPE; i++) {
 270                 struct alarm_base *base = &alarm_bases[i];
 271                 struct timerqueue_node *next;
 272                 ktime_t delta;
 273
 274                 spin_lock_irqsave(&base->lock, flags);
 275                 next = timerqueue_getnext(&base->timerqueue);
 276                 spin_unlock_irqrestore(&base->lock, flags);
 277                 if (!next)
 278                         continue;
 279                 delta = ktime_sub(next->expires, base->gettime());
 280                 if (!min || (delta < min)) {
 281                         expires = next->expires;
 282                         min = delta;
 283                         type = i;
 284                 }
 285         }
 286         if (min == 0)
 287                 return 0;
 288
 289         if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
 290                 __pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
 291                 return -EBUSY;
 292         }
 293
 294         trace_alarmtimer_suspend(expires, type);
 295
 296         /* Setup an rtc timer to fire that far in the future */
 297         rtc_timer_cancel(rtc, &rtctimer);
 298         rtc_read_time(rtc, &tm);
 299         now = rtc_tm_to_ktime(tm);
 300         now = ktime_add(now, min);
 301
 302         /* Set alarm, if in the past reject suspend briefly to handle */
 303         ret = rtc_timer_start(rtc, &rtctimer, now, 0);
 304         if (ret < 0)
 305                 __pm_wakeup_event(ws, MSEC_PER_SEC);
 306         return ret;
 307 }
 308
 309 static int alarmtimer_resume(struct device *dev)
 310 {
 311         struct rtc_device *rtc;
 312
 313         rtc = alarmtimer_get_rtcdev();
 314         if (rtc)
 315                 rtc_timer_cancel(rtc, &rtctimer);
 316         return 0;
 317 }
 318
 319 #else
 320 static int alarmtimer_suspend(struct device *dev)
 321 {
 322         return 0;
 323 }
 324
 325 static int alarmtimer_resume(struct device *dev)
 326 {
 327         return 0;
 328 }
 329 #endif
 330
 331 static void
 332 __alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 333              enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 334 {
 335         timerqueue_init(&alarm->node);
 336         alarm->timer.function = alarmtimer_fired;
 337         alarm->function = function;
 338         alarm->type = type;
 339         alarm->state = ALARMTIMER_STATE_INACTIVE;
 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         hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
 352                      HRTIMER_MODE_ABS);
 353         __alarm_init(alarm, type, function);
 354 }
 355 EXPORT_SYMBOL_GPL(alarm_init);
 356
 357 /**
 358  * alarm_start - Sets an absolute alarm to fire
 359  * @alarm: ptr to alarm to set
 360  * @start: time to run the alarm
 361  */
 362 void alarm_start(struct alarm *alarm, ktime_t start)
 363 {
 364         struct alarm_base *base = &alarm_bases[alarm->type];
 365         unsigned long flags;
 366
 367         spin_lock_irqsave(&base->lock, flags);
 368         alarm->node.expires = start;
 369         alarmtimer_enqueue(base, alarm);
 370         hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
 371         spin_unlock_irqrestore(&base->lock, flags);
 372
 373         trace_alarmtimer_start(alarm, base->gettime());
 374 }
 375 EXPORT_SYMBOL_GPL(alarm_start);
 376
 377 /**
 378  * alarm_start_relative - Sets a relative alarm to fire
 379  * @alarm: ptr to alarm to set
 380  * @start: time relative to now to run the alarm
 381  */
 382 void alarm_start_relative(struct alarm *alarm, ktime_t start)
 383 {
 384         struct alarm_base *base = &alarm_bases[alarm->type];
 385
 386         start = ktime_add_safe(start, base->gettime());
 387         alarm_start(alarm, start);
 388 }
 389 EXPORT_SYMBOL_GPL(alarm_start_relative);
 390
 391 void alarm_restart(struct alarm *alarm)
 392 {
 393         struct alarm_base *base = &alarm_bases[alarm->type];
 394         unsigned long flags;
 395
 396         spin_lock_irqsave(&base->lock, flags);
 397         hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 398         hrtimer_restart(&alarm->timer);
 399         alarmtimer_enqueue(base, alarm);
 400         spin_unlock_irqrestore(&base->lock, flags);
 401 }
 402 EXPORT_SYMBOL_GPL(alarm_restart);
 403
 404 /**
 405  * alarm_try_to_cancel - Tries to cancel an alarm timer
 406  * @alarm: ptr to alarm to be canceled
 407  *
 408  * Returns 1 if the timer was canceled, 0 if it was not running,
 409  * and -1 if the callback was running
 410  */
 411 int alarm_try_to_cancel(struct alarm *alarm)
 412 {
 413         struct alarm_base *base = &alarm_bases[alarm->type];
 414         unsigned long flags;
 415         int ret;
 416
 417         spin_lock_irqsave(&base->lock, flags);
 418         ret = hrtimer_try_to_cancel(&alarm->timer);
 419         if (ret >= 0)
 420                 alarmtimer_dequeue(base, alarm);
 421         spin_unlock_irqrestore(&base->lock, flags);
 422
 423         trace_alarmtimer_cancel(alarm, base->gettime());
 424         return ret;
 425 }
 426 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
 427
 428
 429 /**
 430  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
 431  * @alarm: ptr to alarm to be canceled
 432  *
 433  * Returns 1 if the timer was canceled, 0 if it was not active.
 434  */
 435 int alarm_cancel(struct alarm *alarm)
 436 {
 437         for (;;) {
 438                 int ret = alarm_try_to_cancel(alarm);
 439                 if (ret >= 0)
 440                         return ret;
 441                 cpu_relax();
 442         }
 443 }
 444 EXPORT_SYMBOL_GPL(alarm_cancel);
 445
 446
 447 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
 448 {
 449         u64 overrun = 1;
 450         ktime_t delta;
 451
 452         delta = ktime_sub(now, alarm->node.expires);
 453
 454         if (delta < 0)
 455                 return 0;
 456
 457         if (unlikely(delta >= interval)) {
 458                 s64 incr = ktime_to_ns(interval);
 459
 460                 overrun = ktime_divns(delta, incr);
 461
 462                 alarm->node.expires = ktime_add_ns(alarm->node.expires,
 463                                                         incr*overrun);
 464
 465                 if (alarm->node.expires > now)
 466                         return overrun;
 467                 /*
 468                  * This (and the ktime_add() below) is the
 469                  * correction for exact:
 470                  */
 471                 overrun++;
 472         }
 473
 474         alarm->node.expires = ktime_add_safe(alarm->node.expires, interval);
 475         return overrun;
 476 }
 477 EXPORT_SYMBOL_GPL(alarm_forward);
 478
 479 static u64 __alarm_forward_now(struct alarm *alarm, ktime_t interval, bool throttle)
 480 {
 481         struct alarm_base *base = &alarm_bases[alarm->type];
 482         ktime_t now = base->gettime();
 483
 484         if (IS_ENABLED(CONFIG_HIGH_RES_TIMERS) && throttle) {
 485                 /*
 486                  * Same issue as with posix_timer_fn(). Timers which are
 487                  * periodic but the signal is ignored can starve the system
 488                  * with a very small interval. The real fix which was
 489                  * promised in the context of posix_timer_fn() never
 490                  * materialized, but someone should really work on it.
 491                  *
 492                  * To prevent DOS fake @now to be 1 jiffie out which keeps
 493                  * the overrun accounting correct but creates an
 494                  * inconsistency vs. timer_gettime(2).
 495                  */
 496                 ktime_t kj = NSEC_PER_SEC / HZ;
 497
 498                 if (interval < kj)
 499                         now = ktime_add(now, kj);
 500         }
 501
 502         return alarm_forward(alarm, now, interval);
 503 }
 504
 505 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 506 {
 507         return __alarm_forward_now(alarm, interval, false);
 508 }
 509 EXPORT_SYMBOL_GPL(alarm_forward_now);
 510
 511 #ifdef CONFIG_POSIX_TIMERS
 512
 513 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 514 {
 515         struct alarm_base *base;
 516         unsigned long flags;
 517         ktime_t delta;
 518
 519         switch(type) {
 520         case ALARM_REALTIME:
 521                 base = &alarm_bases[ALARM_REALTIME];
 522                 type = ALARM_REALTIME_FREEZER;
 523                 break;
 524         case ALARM_BOOTTIME:
 525                 base = &alarm_bases[ALARM_BOOTTIME];
 526                 type = ALARM_BOOTTIME_FREEZER;
 527                 break;
 528         default:
 529                 WARN_ONCE(1, "Invalid alarm type: %d\n", type);
 530                 return;
 531         }
 532
 533         delta = ktime_sub(absexp, base->gettime());
 534
 535         spin_lock_irqsave(&freezer_delta_lock, flags);
 536         if (!freezer_delta || (delta < freezer_delta)) {
 537                 freezer_delta = delta;
 538                 freezer_expires = absexp;
 539                 freezer_alarmtype = type;
 540         }
 541         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 542 }
 543
 544 /**
 545  * clock2alarm - helper that converts from clockid to alarmtypes
 546  * @clockid: clockid.
 547  */
 548 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 549 {
 550         if (clockid == CLOCK_REALTIME_ALARM)
 551                 return ALARM_REALTIME;
 552         if (clockid == CLOCK_BOOTTIME_ALARM)
 553                 return ALARM_BOOTTIME;
 554         return -1;
 555 }
 556
 557 /**
 558  * alarm_handle_timer - Callback for posix timers
 559  * @alarm: alarm that fired
 560  *
 561  * Posix timer callback for expired alarm timers.
 562  */
 563 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 564                                                         ktime_t now)
 565 {
 566         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 567                                             it.alarm.alarmtimer);
 568         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
 569         unsigned long flags;
 570         int si_private = 0;
 571
 572         spin_lock_irqsave(&ptr->it_lock, flags);
 573
 574         ptr->it_active = 0;
 575         if (ptr->it_interval)
 576                 si_private = ++ptr->it_requeue_pending;
 577
 578         if (posix_timer_event(ptr, si_private) && ptr->it_interval) {
 579                 /*
 580                  * Handle ignored signals and rearm the timer. This will go
 581                  * away once we handle ignored signals proper. Ensure that
 582                  * small intervals cannot starve the system.
 583                  */
 584                 ptr->it_overrun += __alarm_forward_now(alarm, ptr->it_interval, true);
 585                 ++ptr->it_requeue_pending;
 586                 ptr->it_active = 1;
 587                 result = ALARMTIMER_RESTART;
 588         }
 589         spin_unlock_irqrestore(&ptr->it_lock, flags);
 590
 591         return result;
 592 }
 593
 594 /**
 595  * alarm_timer_rearm - Posix timer callback for rearming timer
 596  * @timr:       Pointer to the posixtimer data struct
 597  */
 598 static void alarm_timer_rearm(struct k_itimer *timr)
 599 {
 600         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 601
 602         timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
 603         alarm_start(alarm, alarm->node.expires);
 604 }
 605
 606 /**
 607  * alarm_timer_forward - Posix timer callback for forwarding timer
 608  * @timr:       Pointer to the posixtimer data struct
 609  * @now:        Current time to forward the timer against
 610  */
 611 static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
 612 {
 613         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 614
 615         return alarm_forward(alarm, timr->it_interval, now);
 616 }
 617
 618 /**
 619  * alarm_timer_remaining - Posix timer callback to retrieve remaining time
 620  * @timr:       Pointer to the posixtimer data struct
 621  * @now:        Current time to calculate against
 622  */
 623 static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
 624 {
 625         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 626
 627         return ktime_sub(alarm->node.expires, now);
 628 }
 629
 630 /**
 631  * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
 632  * @timr:       Pointer to the posixtimer data struct
 633  */
 634 static int alarm_timer_try_to_cancel(struct k_itimer *timr)
 635 {
 636         return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
 637 }
 638
 639 /**
 640  * alarm_timer_arm - Posix timer callback to arm a timer
 641  * @timr:       Pointer to the posixtimer data struct
 642  * @expires:    The new expiry time
 643  * @absolute:   Expiry value is absolute time
 644  * @sigev_none: Posix timer does not deliver signals
 645  */
 646 static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
 647                             bool absolute, bool sigev_none)
 648 {
 649         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 650         struct alarm_base *base = &alarm_bases[alarm->type];
 651
 652         if (!absolute)
 653                 expires = ktime_add_safe(expires, base->gettime());
 654         if (sigev_none)
 655                 alarm->node.expires = expires;
 656         else
 657                 alarm_start(&timr->it.alarm.alarmtimer, expires);
 658 }
 659
 660 /**
 661  * alarm_clock_getres - posix getres interface
 662  * @which_clock: clockid
 663  * @tp: timespec to fill
 664  *
 665  * Returns the granularity of underlying alarm base clock
 666  */
 667 static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 668 {
 669         if (!alarmtimer_get_rtcdev())
 670                 return -EINVAL;
 671
 672         tp->tv_sec = 0;
 673         tp->tv_nsec = hrtimer_resolution;
 674         return 0;
 675 }
 676
 677 /**
 678  * alarm_clock_get - posix clock_get interface
 679  * @which_clock: clockid
 680  * @tp: timespec to fill.
 681  *
 682  * Provides the underlying alarm base time.
 683  */
 684 static int alarm_clock_get(clockid_t which_clock, struct timespec64 *tp)
 685 {
 686         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 687
 688         if (!alarmtimer_get_rtcdev())
 689                 return -EINVAL;
 690
 691         *tp = ktime_to_timespec64(base->gettime());
 692         return 0;
 693 }
 694
 695 /**
 696  * alarm_timer_create - posix timer_create interface
 697  * @new_timer: k_itimer pointer to manage
 698  *
 699  * Initializes the k_itimer structure.
 700  */
 701 static int alarm_timer_create(struct k_itimer *new_timer)
 702 {
 703         enum  alarmtimer_type type;
 704
 705         if (!alarmtimer_get_rtcdev())
 706                 return -EOPNOTSUPP;
 707
 708         if (!capable(CAP_WAKE_ALARM))
 709                 return -EPERM;
 710
 711         type = clock2alarm(new_timer->it_clock);
 712         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 713         return 0;
 714 }
 715
 716 /**
 717  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 718  * @alarm: ptr to alarm that fired
 719  *
 720  * Wakes up the task that set the alarmtimer
 721  */
 722 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 723                                                                 ktime_t now)
 724 {
 725         struct task_struct *task = (struct task_struct *)alarm->data;
 726
 727         alarm->data = NULL;
 728         if (task)
 729                 wake_up_process(task);
 730         return ALARMTIMER_NORESTART;
 731 }
 732
 733 /**
 734  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 735  * @alarm: ptr to alarmtimer
 736  * @absexp: absolute expiration time
 737  *
 738  * Sets the alarm timer and sleeps until it is fired or interrupted.
 739  */
 740 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
 741                                 enum alarmtimer_type type)
 742 {
 743         struct restart_block *restart;
 744         alarm->data = (void *)current;
 745         do {
 746                 set_current_state(TASK_INTERRUPTIBLE);
 747                 alarm_start(alarm, absexp);
 748                 if (likely(alarm->data))
 749                         schedule();
 750
 751                 alarm_cancel(alarm);
 752         } while (alarm->data && !signal_pending(current));
 753
 754         __set_current_state(TASK_RUNNING);
 755
 756         destroy_hrtimer_on_stack(&alarm->timer);
 757
 758         if (!alarm->data)
 759                 return 0;
 760
 761         if (freezing(current))
 762                 alarmtimer_freezerset(absexp, type);
 763         restart = &current->restart_block;
 764         if (restart->nanosleep.type != TT_NONE) {
 765                 struct timespec64 rmt;
 766                 ktime_t rem;
 767
 768                 rem = ktime_sub(absexp, alarm_bases[type].gettime());
 769
 770                 if (rem <= 0)
 771                         return 0;
 772                 rmt = ktime_to_timespec64(rem);
 773
 774                 return nanosleep_copyout(restart, &rmt);
 775         }
 776         return -ERESTART_RESTARTBLOCK;
 777 }
 778
 779 static void
 780 alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
 781                     enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 782 {
 783         hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid,
 784                               HRTIMER_MODE_ABS);
 785         __alarm_init(alarm, type, function);
 786 }
 787
 788 /**
 789  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 790  * @restart: ptr to restart block
 791  *
 792  * Handles restarted clock_nanosleep calls
 793  */
 794 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 795 {
 796         enum  alarmtimer_type type = restart->nanosleep.clockid;
 797         ktime_t exp = restart->nanosleep.expires;
 798         struct alarm alarm;
 799
 800         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 801
 802         return alarmtimer_do_nsleep(&alarm, exp, type);
 803 }
 804
 805 /**
 806  * alarm_timer_nsleep - alarmtimer nanosleep
 807  * @which_clock: clockid
 808  * @flags: determins abstime or relative
 809  * @tsreq: requested sleep time (abs or rel)
 810  * @rmtp: remaining sleep time saved
 811  *
 812  * Handles clock_nanosleep calls against _ALARM clockids
 813  */
 814 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 815                               const struct timespec64 *tsreq)
 816 {
 817         enum  alarmtimer_type type = clock2alarm(which_clock);
 818         struct restart_block *restart = &current->restart_block;
 819         struct alarm alarm;
 820         ktime_t exp;
 821         int ret = 0;
 822
 823         if (!alarmtimer_get_rtcdev())
 824                 return -EOPNOTSUPP;
 825
 826         if (flags & ~TIMER_ABSTIME)
 827                 return -EINVAL;
 828
 829         if (!capable(CAP_WAKE_ALARM))
 830                 return -EPERM;
 831
 832         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 833
 834         exp = timespec64_to_ktime(*tsreq);
 835         /* Convert (if necessary) to absolute time */
 836         if (flags != TIMER_ABSTIME) {
 837                 ktime_t now = alarm_bases[type].gettime();
 838
 839                 exp = ktime_add_safe(now, exp);
 840         }
 841
 842         ret = alarmtimer_do_nsleep(&alarm, exp, type);
 843         if (ret != -ERESTART_RESTARTBLOCK)
 844                 return ret;
 845
 846         /* abs timers don't set remaining time or restart */
 847         if (flags == TIMER_ABSTIME)
 848                 return -ERESTARTNOHAND;
 849
 850         restart->nanosleep.clockid = type;
 851         restart->nanosleep.expires = exp;
 852         set_restart_fn(restart, alarm_timer_nsleep_restart);
 853         return ret;
 854 }
 855
 856 const struct k_clock alarm_clock = {
 857         .clock_getres           = alarm_clock_getres,
 858         .clock_get              = alarm_clock_get,
 859         .timer_create           = alarm_timer_create,
 860         .timer_set              = common_timer_set,
 861         .timer_del              = common_timer_del,
 862         .timer_get              = common_timer_get,
 863         .timer_arm              = alarm_timer_arm,
 864         .timer_rearm            = alarm_timer_rearm,
 865         .timer_forward          = alarm_timer_forward,
 866         .timer_remaining        = alarm_timer_remaining,
 867         .timer_try_to_cancel    = alarm_timer_try_to_cancel,
 868         .nsleep                 = alarm_timer_nsleep,
 869 };
 870 #endif /* CONFIG_POSIX_TIMERS */
 871
 872
 873 /* Suspend hook structures */
 874 static const struct dev_pm_ops alarmtimer_pm_ops = {
 875         .suspend = alarmtimer_suspend,
 876         .resume = alarmtimer_resume,
 877 };
 878
 879 static struct platform_driver alarmtimer_driver = {
 880         .driver = {
 881                 .name = "alarmtimer",
 882                 .pm = &alarmtimer_pm_ops,
 883         }
 884 };
 885
 886 /**
 887  * alarmtimer_init - Initialize alarm timer code
 888  *
 889  * This function initializes the alarm bases and registers
 890  * the posix clock ids.
 891  */
 892 static int __init alarmtimer_init(void)
 893 {
 894         struct platform_device *pdev;
 895         int error = 0;
 896         int i;
 897
 898         alarmtimer_rtc_timer_init();
 899
 900         /* Initialize alarm bases */
 901         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 902         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
 903         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 904         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
 905         for (i = 0; i < ALARM_NUMTYPE; i++) {
 906                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 907                 spin_lock_init(&alarm_bases[i].lock);
 908         }
 909
 910         error = alarmtimer_rtc_interface_setup();
 911         if (error)
 912                 return error;
 913
 914         error = platform_driver_register(&alarmtimer_driver);
 915         if (error)
 916                 goto out_if;
 917
 918         pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
 919         if (IS_ERR(pdev)) {
 920                 error = PTR_ERR(pdev);
 921                 goto out_drv;
 922         }
 923         return 0;
 924
 925 out_drv:
 926         platform_driver_unregister(&alarmtimer_driver);
 927 out_if:
 928         alarmtimer_rtc_interface_remove();
 929         return error;
 930 }
 931 device_initcall(alarmtimer_init);