kernel/time/alarmtimer.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Alarmtimer interface
   4  *
   5  * This interface provides a timer which is similarto hrtimers,
   6  * but triggers a RTC alarm if the box is suspend.
   7  *
   8  * This interface is influenced by the Android RTC Alarm timer
   9  * interface.
  10  *
  11  * Copyright (C) 2010 IBM Corperation
  12  *
  13  * Author: John Stultz <john.stultz@linaro.org>
  14  */
  15 #include <linux/time.h>
  16 #include <linux/hrtimer.h>
  17 #include <linux/timerqueue.h>
  18 #include <linux/rtc.h>
  19 #include <linux/sched/signal.h>
  20 #include <linux/sched/debug.h>
  21 #include <linux/alarmtimer.h>
  22 #include <linux/mutex.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/posix-timers.h>
  25 #include <linux/workqueue.h>
  26 #include <linux/freezer.h>
  27 #include <linux/compat.h>
  28 #include <linux/module.h>
  29
  30 #include "posix-timers.h"
  31
  32 #define CREATE_TRACE_POINTS
  33 #include <trace/events/alarmtimer.h>
  34
  35 /**
  36  * struct alarm_base - Alarm timer bases
  37  * @lock:               Lock for syncrhonized access to the base
  38  * @timerqueue:         Timerqueue head managing the list of events
  39  * @gettime:            Function to read the time correlating to the base
  40  * @base_clockid:       clockid for the base
  41  */
  42 static struct alarm_base {
  43         spinlock_t              lock;
  44         struct timerqueue_head  timerqueue;
  45         ktime_t                 (*gettime)(void);
  46         clockid_t               base_clockid;
  47 } alarm_bases[ALARM_NUMTYPE];
  48
  49 #if defined(CONFIG_POSIX_TIMERS) || defined(CONFIG_RTC_CLASS)
  50 /* freezer information to handle clock_nanosleep triggered wakeups */
  51 static enum alarmtimer_type freezer_alarmtype;
  52 static ktime_t freezer_expires;
  53 static ktime_t freezer_delta;
  54 static DEFINE_SPINLOCK(freezer_delta_lock);
  55 #endif
  56
  57 #ifdef CONFIG_RTC_CLASS
  58 static struct wakeup_source *ws;
  59
  60 /* rtc timer and device for setting alarm wakeups at suspend */
  61 static struct rtc_timer         rtctimer;
  62 static struct rtc_device        *rtcdev;
  63 static DEFINE_SPINLOCK(rtcdev_lock);
  64
  65 /**
  66  * alarmtimer_get_rtcdev - Return selected rtcdevice
  67  *
  68  * This function returns the rtc device to use for wakealarms.
  69  * If one has not already been chosen, it checks to see if a
  70  * functional rtc device is available.
  71  */
  72 struct rtc_device *alarmtimer_get_rtcdev(void)
  73 {
  74         unsigned long flags;
  75         struct rtc_device *ret;
  76
  77         spin_lock_irqsave(&rtcdev_lock, flags);
  78         ret = rtcdev;
  79         spin_unlock_irqrestore(&rtcdev_lock, flags);
  80
  81         return ret;
  82 }
  83 EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
  84
  85 static int alarmtimer_rtc_add_device(struct device *dev,
  86                                 struct class_interface *class_intf)
  87 {
  88         unsigned long flags;
  89         struct rtc_device *rtc = to_rtc_device(dev);
  90         struct wakeup_source *__ws;
  91
  92         if (rtcdev)
  93                 return -EBUSY;
  94
  95         if (!rtc->ops->set_alarm)
  96                 return -1;
  97         if (!device_may_wakeup(rtc->dev.parent))
  98                 return -1;
  99
 100         __ws = wakeup_source_register("alarmtimer");
 101
 102         spin_lock_irqsave(&rtcdev_lock, flags);
 103         if (!rtcdev) {
 104                 if (!try_module_get(rtc->owner)) {
 105                         spin_unlock_irqrestore(&rtcdev_lock, flags);
 106                         return -1;
 107                 }
 108
 109                 rtcdev = rtc;
 110                 /* hold a reference so it doesn't go away */
 111                 get_device(dev);
 112                 ws = __ws;
 113                 __ws = NULL;
 114         }
 115         spin_unlock_irqrestore(&rtcdev_lock, flags);
 116
 117         wakeup_source_unregister(__ws);
 118
 119         return 0;
 120 }
 121
 122 static inline void alarmtimer_rtc_timer_init(void)
 123 {
 124         rtc_timer_init(&rtctimer, NULL, NULL);
 125 }
 126
 127 static struct class_interface alarmtimer_rtc_interface = {
 128         .add_dev = &alarmtimer_rtc_add_device,
 129 };
 130
 131 static int alarmtimer_rtc_interface_setup(void)
 132 {
 133         alarmtimer_rtc_interface.class = rtc_class;
 134         return class_interface_register(&alarmtimer_rtc_interface);
 135 }
 136 static void alarmtimer_rtc_interface_remove(void)
 137 {
 138         class_interface_unregister(&alarmtimer_rtc_interface);
 139 }
 140 #else
 141 struct rtc_device *alarmtimer_get_rtcdev(void)
 142 {
 143         return NULL;
 144 }
 145 #define rtcdev (NULL)
 146 static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
 147 static inline void alarmtimer_rtc_interface_remove(void) { }
 148 static inline void alarmtimer_rtc_timer_init(void) { }
 149 #endif
 150
 151 /**
 152  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
 153  * @base: pointer to the base where the timer is being run
 154  * @alarm: pointer to alarm being enqueued.
 155  *
 156  * Adds alarm to a alarm_base timerqueue
 157  *
 158  * Must hold base->lock when calling.
 159  */
 160 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
 161 {
 162         if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
 163                 timerqueue_del(&base->timerqueue, &alarm->node);
 164
 165         timerqueue_add(&base->timerqueue, &alarm->node);
 166         alarm->state |= ALARMTIMER_STATE_ENQUEUED;
 167 }
 168
 169 /**
 170  * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
 171  * @base: pointer to the base where the timer is running
 172  * @alarm: pointer to alarm being removed
 173  *
 174  * Removes alarm to a alarm_base timerqueue
 175  *
 176  * Must hold base->lock when calling.
 177  */
 178 static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
 179 {
 180         if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
 181                 return;
 182
 183         timerqueue_del(&base->timerqueue, &alarm->node);
 184         alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
 185 }
 186
 187
 188 /**
 189  * alarmtimer_fired - Handles alarm hrtimer being fired.
 190  * @timer: pointer to hrtimer being run
 191  *
 192  * When a alarm timer fires, this runs through the timerqueue to
 193  * see which alarms expired, and runs those. If there are more alarm
 194  * timers queued for the future, we set the hrtimer to fire when
 195  * when the next future alarm timer expires.
 196  */
 197 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 198 {
 199         struct alarm *alarm = container_of(timer, struct alarm, timer);
 200         struct alarm_base *base = &alarm_bases[alarm->type];
 201         unsigned long flags;
 202         int ret = HRTIMER_NORESTART;
 203         int restart = ALARMTIMER_NORESTART;
 204
 205         spin_lock_irqsave(&base->lock, flags);
 206         alarmtimer_dequeue(base, alarm);
 207         spin_unlock_irqrestore(&base->lock, flags);
 208
 209         if (alarm->function)
 210                 restart = alarm->function(alarm, base->gettime());
 211
 212         spin_lock_irqsave(&base->lock, flags);
 213         if (restart != ALARMTIMER_NORESTART) {
 214                 hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 215                 alarmtimer_enqueue(base, alarm);
 216                 ret = HRTIMER_RESTART;
 217         }
 218         spin_unlock_irqrestore(&base->lock, flags);
 219
 220         trace_alarmtimer_fired(alarm, base->gettime());
 221         return ret;
 222
 223 }
 224
 225 ktime_t alarm_expires_remaining(const struct alarm *alarm)
 226 {
 227         struct alarm_base *base = &alarm_bases[alarm->type];
 228         return ktime_sub(alarm->node.expires, base->gettime());
 229 }
 230 EXPORT_SYMBOL_GPL(alarm_expires_remaining);
 231
 232 #ifdef CONFIG_RTC_CLASS
 233 /**
 234  * alarmtimer_suspend - Suspend time callback
 235  * @dev: unused
 236  *
 237  * When we are going into suspend, we look through the bases
 238  * to see which is the soonest timer to expire. We then
 239  * set an rtc timer to fire that far into the future, which
 240  * will wake us from suspend.
 241  */
 242 static int alarmtimer_suspend(struct device *dev)
 243 {
 244         ktime_t min, now, expires;
 245         int i, ret, type;
 246         struct rtc_device *rtc;
 247         unsigned long flags;
 248         struct rtc_time tm;
 249
 250         spin_lock_irqsave(&freezer_delta_lock, flags);
 251         min = freezer_delta;
 252         expires = freezer_expires;
 253         type = freezer_alarmtype;
 254         freezer_delta = 0;
 255         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 256
 257         rtc = alarmtimer_get_rtcdev();
 258         /* If we have no rtcdev, just return */
 259         if (!rtc)
 260                 return 0;
 261
 262         /* Find the soonest timer to expire*/
 263         for (i = 0; i < ALARM_NUMTYPE; i++) {
 264                 struct alarm_base *base = &alarm_bases[i];
 265                 struct timerqueue_node *next;
 266                 ktime_t delta;
 267
 268                 spin_lock_irqsave(&base->lock, flags);
 269                 next = timerqueue_getnext(&base->timerqueue);
 270                 spin_unlock_irqrestore(&base->lock, flags);
 271                 if (!next)
 272                         continue;
 273                 delta = ktime_sub(next->expires, base->gettime());
 274                 if (!min || (delta < min)) {
 275                         expires = next->expires;
 276                         min = delta;
 277                         type = i;
 278                 }
 279         }
 280         if (min == 0)
 281                 return 0;
 282
 283         if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
 284                 __pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
 285                 return -EBUSY;
 286         }
 287
 288         trace_alarmtimer_suspend(expires, type);
 289
 290         /* Setup an rtc timer to fire that far in the future */
 291         rtc_timer_cancel(rtc, &rtctimer);
 292         rtc_read_time(rtc, &tm);
 293         now = rtc_tm_to_ktime(tm);
 294         now = ktime_add(now, min);
 295
 296         /* Set alarm, if in the past reject suspend briefly to handle */
 297         ret = rtc_timer_start(rtc, &rtctimer, now, 0);
 298         if (ret < 0)
 299                 __pm_wakeup_event(ws, MSEC_PER_SEC);
 300         return ret;
 301 }
 302
 303 static int alarmtimer_resume(struct device *dev)
 304 {
 305         struct rtc_device *rtc;
 306
 307         rtc = alarmtimer_get_rtcdev();
 308         if (rtc)
 309                 rtc_timer_cancel(rtc, &rtctimer);
 310         return 0;
 311 }
 312
 313 #else
 314 static int alarmtimer_suspend(struct device *dev)
 315 {
 316         return 0;
 317 }
 318
 319 static int alarmtimer_resume(struct device *dev)
 320 {
 321         return 0;
 322 }
 323 #endif
 324
 325 static void
 326 __alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 327              enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 328 {
 329         timerqueue_init(&alarm->node);
 330         alarm->timer.function = alarmtimer_fired;
 331         alarm->function = function;
 332         alarm->type = type;
 333         alarm->state = ALARMTIMER_STATE_INACTIVE;
 334 }
 335
 336 /**
 337  * alarm_init - Initialize an alarm structure
 338  * @alarm: ptr to alarm to be initialized
 339  * @type: the type of the alarm
 340  * @function: callback that is run when the alarm fires
 341  */
 342 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 343                 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 344 {
 345         hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
 346                      HRTIMER_MODE_ABS);
 347         __alarm_init(alarm, type, function);
 348 }
 349 EXPORT_SYMBOL_GPL(alarm_init);
 350
 351 /**
 352  * alarm_start - Sets an absolute alarm to fire
 353  * @alarm: ptr to alarm to set
 354  * @start: time to run the alarm
 355  */
 356 void alarm_start(struct alarm *alarm, ktime_t start)
 357 {
 358         struct alarm_base *base = &alarm_bases[alarm->type];
 359         unsigned long flags;
 360
 361         spin_lock_irqsave(&base->lock, flags);
 362         alarm->node.expires = start;
 363         alarmtimer_enqueue(base, alarm);
 364         hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
 365         spin_unlock_irqrestore(&base->lock, flags);
 366
 367         trace_alarmtimer_start(alarm, base->gettime());
 368 }
 369 EXPORT_SYMBOL_GPL(alarm_start);
 370
 371 /**
 372  * alarm_start_relative - Sets a relative alarm to fire
 373  * @alarm: ptr to alarm to set
 374  * @start: time relative to now to run the alarm
 375  */
 376 void alarm_start_relative(struct alarm *alarm, ktime_t start)
 377 {
 378         struct alarm_base *base = &alarm_bases[alarm->type];
 379
 380         start = ktime_add_safe(start, base->gettime());
 381         alarm_start(alarm, start);
 382 }
 383 EXPORT_SYMBOL_GPL(alarm_start_relative);
 384
 385 void alarm_restart(struct alarm *alarm)
 386 {
 387         struct alarm_base *base = &alarm_bases[alarm->type];
 388         unsigned long flags;
 389
 390         spin_lock_irqsave(&base->lock, flags);
 391         hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 392         hrtimer_restart(&alarm->timer);
 393         alarmtimer_enqueue(base, alarm);
 394         spin_unlock_irqrestore(&base->lock, flags);
 395 }
 396 EXPORT_SYMBOL_GPL(alarm_restart);
 397
 398 /**
 399  * alarm_try_to_cancel - Tries to cancel an alarm timer
 400  * @alarm: ptr to alarm to be canceled
 401  *
 402  * Returns 1 if the timer was canceled, 0 if it was not running,
 403  * and -1 if the callback was running
 404  */
 405 int alarm_try_to_cancel(struct alarm *alarm)
 406 {
 407         struct alarm_base *base = &alarm_bases[alarm->type];
 408         unsigned long flags;
 409         int ret;
 410
 411         spin_lock_irqsave(&base->lock, flags);
 412         ret = hrtimer_try_to_cancel(&alarm->timer);
 413         if (ret >= 0)
 414                 alarmtimer_dequeue(base, alarm);
 415         spin_unlock_irqrestore(&base->lock, flags);
 416
 417         trace_alarmtimer_cancel(alarm, base->gettime());
 418         return ret;
 419 }
 420 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
 421
 422
 423 /**
 424  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
 425  * @alarm: ptr to alarm to be canceled
 426  *
 427  * Returns 1 if the timer was canceled, 0 if it was not active.
 428  */
 429 int alarm_cancel(struct alarm *alarm)
 430 {
 431         for (;;) {
 432                 int ret = alarm_try_to_cancel(alarm);
 433                 if (ret >= 0)
 434                         return ret;
 435                 cpu_relax();
 436         }
 437 }
 438 EXPORT_SYMBOL_GPL(alarm_cancel);
 439
 440
 441 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
 442 {
 443         u64 overrun = 1;
 444         ktime_t delta;
 445
 446         delta = ktime_sub(now, alarm->node.expires);
 447
 448         if (delta < 0)
 449                 return 0;
 450
 451         if (unlikely(delta >= interval)) {
 452                 s64 incr = ktime_to_ns(interval);
 453
 454                 overrun = ktime_divns(delta, incr);
 455
 456                 alarm->node.expires = ktime_add_ns(alarm->node.expires,
 457                                                         incr*overrun);
 458
 459                 if (alarm->node.expires > now)
 460                         return overrun;
 461                 /*
 462                  * This (and the ktime_add() below) is the
 463                  * correction for exact:
 464                  */
 465                 overrun++;
 466         }
 467
 468         alarm->node.expires = ktime_add_safe(alarm->node.expires, interval);
 469         return overrun;
 470 }
 471 EXPORT_SYMBOL_GPL(alarm_forward);
 472
 473 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 474 {
 475         struct alarm_base *base = &alarm_bases[alarm->type];
 476
 477         return alarm_forward(alarm, base->gettime(), interval);
 478 }
 479 EXPORT_SYMBOL_GPL(alarm_forward_now);
 480
 481 #ifdef CONFIG_POSIX_TIMERS
 482
 483 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 484 {
 485         struct alarm_base *base;
 486         unsigned long flags;
 487         ktime_t delta;
 488
 489         switch(type) {
 490         case ALARM_REALTIME:
 491                 base = &alarm_bases[ALARM_REALTIME];
 492                 type = ALARM_REALTIME_FREEZER;
 493                 break;
 494         case ALARM_BOOTTIME:
 495                 base = &alarm_bases[ALARM_BOOTTIME];
 496                 type = ALARM_BOOTTIME_FREEZER;
 497                 break;
 498         default:
 499                 WARN_ONCE(1, "Invalid alarm type: %d\n", type);
 500                 return;
 501         }
 502
 503         delta = ktime_sub(absexp, base->gettime());
 504
 505         spin_lock_irqsave(&freezer_delta_lock, flags);
 506         if (!freezer_delta || (delta < freezer_delta)) {
 507                 freezer_delta = delta;
 508                 freezer_expires = absexp;
 509                 freezer_alarmtype = type;
 510         }
 511         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 512 }
 513
 514 /**
 515  * clock2alarm - helper that converts from clockid to alarmtypes
 516  * @clockid: clockid.
 517  */
 518 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 519 {
 520         if (clockid == CLOCK_REALTIME_ALARM)
 521                 return ALARM_REALTIME;
 522         if (clockid == CLOCK_BOOTTIME_ALARM)
 523                 return ALARM_BOOTTIME;
 524         return -1;
 525 }
 526
 527 /**
 528  * alarm_handle_timer - Callback for posix timers
 529  * @alarm: alarm that fired
 530  *
 531  * Posix timer callback for expired alarm timers.
 532  */
 533 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 534                                                         ktime_t now)
 535 {
 536         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 537                                             it.alarm.alarmtimer);
 538         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
 539         unsigned long flags;
 540         int si_private = 0;
 541
 542         spin_lock_irqsave(&ptr->it_lock, flags);
 543
 544         ptr->it_active = 0;
 545         if (ptr->it_interval)
 546                 si_private = ++ptr->it_requeue_pending;
 547
 548         if (posix_timer_event(ptr, si_private) && ptr->it_interval) {
 549                 /*
 550                  * Handle ignored signals and rearm the timer. This will go
 551                  * away once we handle ignored signals proper.
 552                  */
 553                 ptr->it_overrun += alarm_forward_now(alarm, ptr->it_interval);
 554                 ++ptr->it_requeue_pending;
 555                 ptr->it_active = 1;
 556                 result = ALARMTIMER_RESTART;
 557         }
 558         spin_unlock_irqrestore(&ptr->it_lock, flags);
 559
 560         return result;
 561 }
 562
 563 /**
 564  * alarm_timer_rearm - Posix timer callback for rearming timer
 565  * @timr:       Pointer to the posixtimer data struct
 566  */
 567 static void alarm_timer_rearm(struct k_itimer *timr)
 568 {
 569         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 570
 571         timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
 572         alarm_start(alarm, alarm->node.expires);
 573 }
 574
 575 /**
 576  * alarm_timer_forward - Posix timer callback for forwarding timer
 577  * @timr:       Pointer to the posixtimer data struct
 578  * @now:        Current time to forward the timer against
 579  */
 580 static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
 581 {
 582         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 583
 584         return alarm_forward(alarm, timr->it_interval, now);
 585 }
 586
 587 /**
 588  * alarm_timer_remaining - Posix timer callback to retrieve remaining time
 589  * @timr:       Pointer to the posixtimer data struct
 590  * @now:        Current time to calculate against
 591  */
 592 static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
 593 {
 594         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 595
 596         return ktime_sub(alarm->node.expires, now);
 597 }
 598
 599 /**
 600  * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
 601  * @timr:       Pointer to the posixtimer data struct
 602  */
 603 static int alarm_timer_try_to_cancel(struct k_itimer *timr)
 604 {
 605         return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
 606 }
 607
 608 /**
 609  * alarm_timer_arm - Posix timer callback to arm a timer
 610  * @timr:       Pointer to the posixtimer data struct
 611  * @expires:    The new expiry time
 612  * @absolute:   Expiry value is absolute time
 613  * @sigev_none: Posix timer does not deliver signals
 614  */
 615 static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
 616                             bool absolute, bool sigev_none)
 617 {
 618         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 619         struct alarm_base *base = &alarm_bases[alarm->type];
 620
 621         if (!absolute)
 622                 expires = ktime_add_safe(expires, base->gettime());
 623         if (sigev_none)
 624                 alarm->node.expires = expires;
 625         else
 626                 alarm_start(&timr->it.alarm.alarmtimer, expires);
 627 }
 628
 629 /**
 630  * alarm_clock_getres - posix getres interface
 631  * @which_clock: clockid
 632  * @tp: timespec to fill
 633  *
 634  * Returns the granularity of underlying alarm base clock
 635  */
 636 static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 637 {
 638         if (!alarmtimer_get_rtcdev())
 639                 return -EINVAL;
 640
 641         tp->tv_sec = 0;
 642         tp->tv_nsec = hrtimer_resolution;
 643         return 0;
 644 }
 645
 646 /**
 647  * alarm_clock_get - posix clock_get interface
 648  * @which_clock: clockid
 649  * @tp: timespec to fill.
 650  *
 651  * Provides the underlying alarm base time.
 652  */
 653 static int alarm_clock_get(clockid_t which_clock, struct timespec64 *tp)
 654 {
 655         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 656
 657         if (!alarmtimer_get_rtcdev())
 658                 return -EINVAL;
 659
 660         *tp = ktime_to_timespec64(base->gettime());
 661         return 0;
 662 }
 663
 664 /**
 665  * alarm_timer_create - posix timer_create interface
 666  * @new_timer: k_itimer pointer to manage
 667  *
 668  * Initializes the k_itimer structure.
 669  */
 670 static int alarm_timer_create(struct k_itimer *new_timer)
 671 {
 672         enum  alarmtimer_type type;
 673
 674         if (!alarmtimer_get_rtcdev())
 675                 return -EOPNOTSUPP;
 676
 677         if (!capable(CAP_WAKE_ALARM))
 678                 return -EPERM;
 679
 680         type = clock2alarm(new_timer->it_clock);
 681         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 682         return 0;
 683 }
 684
 685 /**
 686  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 687  * @alarm: ptr to alarm that fired
 688  *
 689  * Wakes up the task that set the alarmtimer
 690  */
 691 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 692                                                                 ktime_t now)
 693 {
 694         struct task_struct *task = (struct task_struct *)alarm->data;
 695
 696         alarm->data = NULL;
 697         if (task)
 698                 wake_up_process(task);
 699         return ALARMTIMER_NORESTART;
 700 }
 701
 702 /**
 703  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 704  * @alarm: ptr to alarmtimer
 705  * @absexp: absolute expiration time
 706  *
 707  * Sets the alarm timer and sleeps until it is fired or interrupted.
 708  */
 709 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
 710                                 enum alarmtimer_type type)
 711 {
 712         struct restart_block *restart;
 713         alarm->data = (void *)current;
 714         do {
 715                 set_current_state(TASK_INTERRUPTIBLE);
 716                 alarm_start(alarm, absexp);
 717                 if (likely(alarm->data))
 718                         schedule();
 719
 720                 alarm_cancel(alarm);
 721         } while (alarm->data && !signal_pending(current));
 722
 723         __set_current_state(TASK_RUNNING);
 724
 725         destroy_hrtimer_on_stack(&alarm->timer);
 726
 727         if (!alarm->data)
 728                 return 0;
 729
 730         if (freezing(current))
 731                 alarmtimer_freezerset(absexp, type);
 732         restart = &current->restart_block;
 733         if (restart->nanosleep.type != TT_NONE) {
 734                 struct timespec64 rmt;
 735                 ktime_t rem;
 736
 737                 rem = ktime_sub(absexp, alarm_bases[type].gettime());
 738
 739                 if (rem <= 0)
 740                         return 0;
 741                 rmt = ktime_to_timespec64(rem);
 742
 743                 return nanosleep_copyout(restart, &rmt);
 744         }
 745         return -ERESTART_RESTARTBLOCK;
 746 }
 747
 748 static void
 749 alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
 750                     enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 751 {
 752         hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid,
 753                               HRTIMER_MODE_ABS);
 754         __alarm_init(alarm, type, function);
 755 }
 756
 757 /**
 758  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 759  * @restart: ptr to restart block
 760  *
 761  * Handles restarted clock_nanosleep calls
 762  */
 763 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 764 {
 765         enum  alarmtimer_type type = restart->nanosleep.clockid;
 766         ktime_t exp = restart->nanosleep.expires;
 767         struct alarm alarm;
 768
 769         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 770
 771         return alarmtimer_do_nsleep(&alarm, exp, type);
 772 }
 773
 774 /**
 775  * alarm_timer_nsleep - alarmtimer nanosleep
 776  * @which_clock: clockid
 777  * @flags: determins abstime or relative
 778  * @tsreq: requested sleep time (abs or rel)
 779  * @rmtp: remaining sleep time saved
 780  *
 781  * Handles clock_nanosleep calls against _ALARM clockids
 782  */
 783 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 784                               const struct timespec64 *tsreq)
 785 {
 786         enum  alarmtimer_type type = clock2alarm(which_clock);
 787         struct restart_block *restart = &current->restart_block;
 788         struct alarm alarm;
 789         ktime_t exp;
 790         int ret = 0;
 791
 792         if (!alarmtimer_get_rtcdev())
 793                 return -EOPNOTSUPP;
 794
 795         if (flags & ~TIMER_ABSTIME)
 796                 return -EINVAL;
 797
 798         if (!capable(CAP_WAKE_ALARM))
 799                 return -EPERM;
 800
 801         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 802
 803         exp = timespec64_to_ktime(*tsreq);
 804         /* Convert (if necessary) to absolute time */
 805         if (flags != TIMER_ABSTIME) {
 806                 ktime_t now = alarm_bases[type].gettime();
 807
 808                 exp = ktime_add_safe(now, exp);
 809         }
 810
 811         ret = alarmtimer_do_nsleep(&alarm, exp, type);
 812         if (ret != -ERESTART_RESTARTBLOCK)
 813                 return ret;
 814
 815         /* abs timers don't set remaining time or restart */
 816         if (flags == TIMER_ABSTIME)
 817                 return -ERESTARTNOHAND;
 818
 819         restart->fn = alarm_timer_nsleep_restart;
 820         restart->nanosleep.clockid = type;
 821         restart->nanosleep.expires = exp;
 822         return ret;
 823 }
 824
 825 const struct k_clock alarm_clock = {
 826         .clock_getres           = alarm_clock_getres,
 827         .clock_get              = alarm_clock_get,
 828         .timer_create           = alarm_timer_create,
 829         .timer_set              = common_timer_set,
 830         .timer_del              = common_timer_del,
 831         .timer_get              = common_timer_get,
 832         .timer_arm              = alarm_timer_arm,
 833         .timer_rearm            = alarm_timer_rearm,
 834         .timer_forward          = alarm_timer_forward,
 835         .timer_remaining        = alarm_timer_remaining,
 836         .timer_try_to_cancel    = alarm_timer_try_to_cancel,
 837         .nsleep                 = alarm_timer_nsleep,
 838 };
 839 #endif /* CONFIG_POSIX_TIMERS */
 840
 841
 842 /* Suspend hook structures */
 843 static const struct dev_pm_ops alarmtimer_pm_ops = {
 844         .suspend = alarmtimer_suspend,
 845         .resume = alarmtimer_resume,
 846 };
 847
 848 static struct platform_driver alarmtimer_driver = {
 849         .driver = {
 850                 .name = "alarmtimer",
 851                 .pm = &alarmtimer_pm_ops,
 852         }
 853 };
 854
 855 /**
 856  * alarmtimer_init - Initialize alarm timer code
 857  *
 858  * This function initializes the alarm bases and registers
 859  * the posix clock ids.
 860  */
 861 static int __init alarmtimer_init(void)
 862 {
 863         struct platform_device *pdev;
 864         int error = 0;
 865         int i;
 866
 867         alarmtimer_rtc_timer_init();
 868
 869         /* Initialize alarm bases */
 870         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 871         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
 872         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 873         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
 874         for (i = 0; i < ALARM_NUMTYPE; i++) {
 875                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 876                 spin_lock_init(&alarm_bases[i].lock);
 877         }
 878
 879         error = alarmtimer_rtc_interface_setup();
 880         if (error)
 881                 return error;
 882
 883         error = platform_driver_register(&alarmtimer_driver);
 884         if (error)
 885                 goto out_if;
 886
 887         pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
 888         if (IS_ERR(pdev)) {
 889                 error = PTR_ERR(pdev);
 890                 goto out_drv;
 891         }
 892         return 0;
 893
 894 out_drv:
 895         platform_driver_unregister(&alarmtimer_driver);
 896 out_if:
 897         alarmtimer_rtc_interface_remove();
 898         return error;
 899 }
 900 device_initcall(alarmtimer_init);