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 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 480 {
 481         struct alarm_base *base = &alarm_bases[alarm->type];
 482
 483         return alarm_forward(alarm, base->gettime(), interval);
 484 }
 485 EXPORT_SYMBOL_GPL(alarm_forward_now);
 486
 487 #ifdef CONFIG_POSIX_TIMERS
 488
 489 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 490 {
 491         struct alarm_base *base;
 492         unsigned long flags;
 493         ktime_t delta;
 494
 495         switch(type) {
 496         case ALARM_REALTIME:
 497                 base = &alarm_bases[ALARM_REALTIME];
 498                 type = ALARM_REALTIME_FREEZER;
 499                 break;
 500         case ALARM_BOOTTIME:
 501                 base = &alarm_bases[ALARM_BOOTTIME];
 502                 type = ALARM_BOOTTIME_FREEZER;
 503                 break;
 504         default:
 505                 WARN_ONCE(1, "Invalid alarm type: %d\n", type);
 506                 return;
 507         }
 508
 509         delta = ktime_sub(absexp, base->gettime());
 510
 511         spin_lock_irqsave(&freezer_delta_lock, flags);
 512         if (!freezer_delta || (delta < freezer_delta)) {
 513                 freezer_delta = delta;
 514                 freezer_expires = absexp;
 515                 freezer_alarmtype = type;
 516         }
 517         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 518 }
 519
 520 /**
 521  * clock2alarm - helper that converts from clockid to alarmtypes
 522  * @clockid: clockid.
 523  */
 524 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 525 {
 526         if (clockid == CLOCK_REALTIME_ALARM)
 527                 return ALARM_REALTIME;
 528         if (clockid == CLOCK_BOOTTIME_ALARM)
 529                 return ALARM_BOOTTIME;
 530         return -1;
 531 }
 532
 533 /**
 534  * alarm_handle_timer - Callback for posix timers
 535  * @alarm: alarm that fired
 536  *
 537  * Posix timer callback for expired alarm timers.
 538  */
 539 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 540                                                         ktime_t now)
 541 {
 542         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 543                                             it.alarm.alarmtimer);
 544         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
 545         unsigned long flags;
 546         int si_private = 0;
 547
 548         spin_lock_irqsave(&ptr->it_lock, flags);
 549
 550         ptr->it_active = 0;
 551         if (ptr->it_interval)
 552                 si_private = ++ptr->it_requeue_pending;
 553
 554         if (posix_timer_event(ptr, si_private) && ptr->it_interval) {
 555                 /*
 556                  * Handle ignored signals and rearm the timer. This will go
 557                  * away once we handle ignored signals proper.
 558                  */
 559                 ptr->it_overrun += alarm_forward_now(alarm, ptr->it_interval);
 560                 ++ptr->it_requeue_pending;
 561                 ptr->it_active = 1;
 562                 result = ALARMTIMER_RESTART;
 563         }
 564         spin_unlock_irqrestore(&ptr->it_lock, flags);
 565
 566         return result;
 567 }
 568
 569 /**
 570  * alarm_timer_rearm - Posix timer callback for rearming timer
 571  * @timr:       Pointer to the posixtimer data struct
 572  */
 573 static void alarm_timer_rearm(struct k_itimer *timr)
 574 {
 575         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 576
 577         timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
 578         alarm_start(alarm, alarm->node.expires);
 579 }
 580
 581 /**
 582  * alarm_timer_forward - Posix timer callback for forwarding timer
 583  * @timr:       Pointer to the posixtimer data struct
 584  * @now:        Current time to forward the timer against
 585  */
 586 static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
 587 {
 588         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 589
 590         return alarm_forward(alarm, timr->it_interval, now);
 591 }
 592
 593 /**
 594  * alarm_timer_remaining - Posix timer callback to retrieve remaining time
 595  * @timr:       Pointer to the posixtimer data struct
 596  * @now:        Current time to calculate against
 597  */
 598 static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
 599 {
 600         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 601
 602         return ktime_sub(alarm->node.expires, now);
 603 }
 604
 605 /**
 606  * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
 607  * @timr:       Pointer to the posixtimer data struct
 608  */
 609 static int alarm_timer_try_to_cancel(struct k_itimer *timr)
 610 {
 611         return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
 612 }
 613
 614 /**
 615  * alarm_timer_arm - Posix timer callback to arm a timer
 616  * @timr:       Pointer to the posixtimer data struct
 617  * @expires:    The new expiry time
 618  * @absolute:   Expiry value is absolute time
 619  * @sigev_none: Posix timer does not deliver signals
 620  */
 621 static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
 622                             bool absolute, bool sigev_none)
 623 {
 624         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 625         struct alarm_base *base = &alarm_bases[alarm->type];
 626
 627         if (!absolute)
 628                 expires = ktime_add_safe(expires, base->gettime());
 629         if (sigev_none)
 630                 alarm->node.expires = expires;
 631         else
 632                 alarm_start(&timr->it.alarm.alarmtimer, expires);
 633 }
 634
 635 /**
 636  * alarm_clock_getres - posix getres interface
 637  * @which_clock: clockid
 638  * @tp: timespec to fill
 639  *
 640  * Returns the granularity of underlying alarm base clock
 641  */
 642 static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 643 {
 644         if (!alarmtimer_get_rtcdev())
 645                 return -EINVAL;
 646
 647         tp->tv_sec = 0;
 648         tp->tv_nsec = hrtimer_resolution;
 649         return 0;
 650 }
 651
 652 /**
 653  * alarm_clock_get - posix clock_get interface
 654  * @which_clock: clockid
 655  * @tp: timespec to fill.
 656  *
 657  * Provides the underlying alarm base time.
 658  */
 659 static int alarm_clock_get(clockid_t which_clock, struct timespec64 *tp)
 660 {
 661         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 662
 663         if (!alarmtimer_get_rtcdev())
 664                 return -EINVAL;
 665
 666         *tp = ktime_to_timespec64(base->gettime());
 667         return 0;
 668 }
 669
 670 /**
 671  * alarm_timer_create - posix timer_create interface
 672  * @new_timer: k_itimer pointer to manage
 673  *
 674  * Initializes the k_itimer structure.
 675  */
 676 static int alarm_timer_create(struct k_itimer *new_timer)
 677 {
 678         enum  alarmtimer_type type;
 679
 680         if (!alarmtimer_get_rtcdev())
 681                 return -EOPNOTSUPP;
 682
 683         if (!capable(CAP_WAKE_ALARM))
 684                 return -EPERM;
 685
 686         type = clock2alarm(new_timer->it_clock);
 687         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 688         return 0;
 689 }
 690
 691 /**
 692  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 693  * @alarm: ptr to alarm that fired
 694  *
 695  * Wakes up the task that set the alarmtimer
 696  */
 697 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 698                                                                 ktime_t now)
 699 {
 700         struct task_struct *task = (struct task_struct *)alarm->data;
 701
 702         alarm->data = NULL;
 703         if (task)
 704                 wake_up_process(task);
 705         return ALARMTIMER_NORESTART;
 706 }
 707
 708 /**
 709  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 710  * @alarm: ptr to alarmtimer
 711  * @absexp: absolute expiration time
 712  *
 713  * Sets the alarm timer and sleeps until it is fired or interrupted.
 714  */
 715 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
 716                                 enum alarmtimer_type type)
 717 {
 718         struct restart_block *restart;
 719         alarm->data = (void *)current;
 720         do {
 721                 set_current_state(TASK_INTERRUPTIBLE);
 722                 alarm_start(alarm, absexp);
 723                 if (likely(alarm->data))
 724                         schedule();
 725
 726                 alarm_cancel(alarm);
 727         } while (alarm->data && !signal_pending(current));
 728
 729         __set_current_state(TASK_RUNNING);
 730
 731         destroy_hrtimer_on_stack(&alarm->timer);
 732
 733         if (!alarm->data)
 734                 return 0;
 735
 736         if (freezing(current))
 737                 alarmtimer_freezerset(absexp, type);
 738         restart = &current->restart_block;
 739         if (restart->nanosleep.type != TT_NONE) {
 740                 struct timespec64 rmt;
 741                 ktime_t rem;
 742
 743                 rem = ktime_sub(absexp, alarm_bases[type].gettime());
 744
 745                 if (rem <= 0)
 746                         return 0;
 747                 rmt = ktime_to_timespec64(rem);
 748
 749                 return nanosleep_copyout(restart, &rmt);
 750         }
 751         return -ERESTART_RESTARTBLOCK;
 752 }
 753
 754 static void
 755 alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
 756                     enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 757 {
 758         hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid,
 759                               HRTIMER_MODE_ABS);
 760         __alarm_init(alarm, type, function);
 761 }
 762
 763 /**
 764  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 765  * @restart: ptr to restart block
 766  *
 767  * Handles restarted clock_nanosleep calls
 768  */
 769 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 770 {
 771         enum  alarmtimer_type type = restart->nanosleep.clockid;
 772         ktime_t exp = restart->nanosleep.expires;
 773         struct alarm alarm;
 774
 775         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 776
 777         return alarmtimer_do_nsleep(&alarm, exp, type);
 778 }
 779
 780 /**
 781  * alarm_timer_nsleep - alarmtimer nanosleep
 782  * @which_clock: clockid
 783  * @flags: determins abstime or relative
 784  * @tsreq: requested sleep time (abs or rel)
 785  * @rmtp: remaining sleep time saved
 786  *
 787  * Handles clock_nanosleep calls against _ALARM clockids
 788  */
 789 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 790                               const struct timespec64 *tsreq)
 791 {
 792         enum  alarmtimer_type type = clock2alarm(which_clock);
 793         struct restart_block *restart = &current->restart_block;
 794         struct alarm alarm;
 795         ktime_t exp;
 796         int ret = 0;
 797
 798         if (!alarmtimer_get_rtcdev())
 799                 return -EOPNOTSUPP;
 800
 801         if (flags & ~TIMER_ABSTIME)
 802                 return -EINVAL;
 803
 804         if (!capable(CAP_WAKE_ALARM))
 805                 return -EPERM;
 806
 807         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 808
 809         exp = timespec64_to_ktime(*tsreq);
 810         /* Convert (if necessary) to absolute time */
 811         if (flags != TIMER_ABSTIME) {
 812                 ktime_t now = alarm_bases[type].gettime();
 813
 814                 exp = ktime_add_safe(now, exp);
 815         }
 816
 817         ret = alarmtimer_do_nsleep(&alarm, exp, type);
 818         if (ret != -ERESTART_RESTARTBLOCK)
 819                 return ret;
 820
 821         /* abs timers don't set remaining time or restart */
 822         if (flags == TIMER_ABSTIME)
 823                 return -ERESTARTNOHAND;
 824
 825         restart->nanosleep.clockid = type;
 826         restart->nanosleep.expires = exp;
 827         set_restart_fn(restart, alarm_timer_nsleep_restart);
 828         return ret;
 829 }
 830
 831 const struct k_clock alarm_clock = {
 832         .clock_getres           = alarm_clock_getres,
 833         .clock_get              = alarm_clock_get,
 834         .timer_create           = alarm_timer_create,
 835         .timer_set              = common_timer_set,
 836         .timer_del              = common_timer_del,
 837         .timer_get              = common_timer_get,
 838         .timer_arm              = alarm_timer_arm,
 839         .timer_rearm            = alarm_timer_rearm,
 840         .timer_forward          = alarm_timer_forward,
 841         .timer_remaining        = alarm_timer_remaining,
 842         .timer_try_to_cancel    = alarm_timer_try_to_cancel,
 843         .nsleep                 = alarm_timer_nsleep,
 844 };
 845 #endif /* CONFIG_POSIX_TIMERS */
 846
 847
 848 /* Suspend hook structures */
 849 static const struct dev_pm_ops alarmtimer_pm_ops = {
 850         .suspend = alarmtimer_suspend,
 851         .resume = alarmtimer_resume,
 852 };
 853
 854 static struct platform_driver alarmtimer_driver = {
 855         .driver = {
 856                 .name = "alarmtimer",
 857                 .pm = &alarmtimer_pm_ops,
 858         }
 859 };
 860
 861 /**
 862  * alarmtimer_init - Initialize alarm timer code
 863  *
 864  * This function initializes the alarm bases and registers
 865  * the posix clock ids.
 866  */
 867 static int __init alarmtimer_init(void)
 868 {
 869         struct platform_device *pdev;
 870         int error = 0;
 871         int i;
 872
 873         alarmtimer_rtc_timer_init();
 874
 875         /* Initialize alarm bases */
 876         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 877         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
 878         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 879         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
 880         for (i = 0; i < ALARM_NUMTYPE; i++) {
 881                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 882                 spin_lock_init(&alarm_bases[i].lock);
 883         }
 884
 885         error = alarmtimer_rtc_interface_setup();
 886         if (error)
 887                 return error;
 888
 889         error = platform_driver_register(&alarmtimer_driver);
 890         if (error)
 891                 goto out_if;
 892
 893         pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
 894         if (IS_ERR(pdev)) {
 895                 error = PTR_ERR(pdev);
 896                 goto out_drv;
 897         }
 898         return 0;
 899
 900 out_drv:
 901         platform_driver_unregister(&alarmtimer_driver);
 902 out_if:
 903         alarmtimer_rtc_interface_remove();
 904         return error;
 905 }
 906 device_initcall(alarmtimer_init);