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  * @state: unused
 237  *
 238  * When we are going into suspend, we look through the bases
 239  * to see which is the soonest timer to expire. We then
 240  * set an rtc timer to fire that far into the future, which
 241  * will wake us from suspend.
 242  */
 243 static int alarmtimer_suspend(struct device *dev)
 244 {
 245         ktime_t min, now, expires;
 246         int i, ret, type;
 247         struct rtc_device *rtc;
 248         unsigned long flags;
 249         struct rtc_time tm;
 250
 251         spin_lock_irqsave(&freezer_delta_lock, flags);
 252         min = freezer_delta;
 253         expires = freezer_expires;
 254         type = freezer_alarmtype;
 255         freezer_delta = 0;
 256         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 257
 258         rtc = alarmtimer_get_rtcdev();
 259         /* If we have no rtcdev, just return */
 260         if (!rtc)
 261                 return 0;
 262
 263         /* Find the soonest timer to expire*/
 264         for (i = 0; i < ALARM_NUMTYPE; i++) {
 265                 struct alarm_base *base = &alarm_bases[i];
 266                 struct timerqueue_node *next;
 267                 ktime_t delta;
 268
 269                 spin_lock_irqsave(&base->lock, flags);
 270                 next = timerqueue_getnext(&base->timerqueue);
 271                 spin_unlock_irqrestore(&base->lock, flags);
 272                 if (!next)
 273                         continue;
 274                 delta = ktime_sub(next->expires, base->gettime());
 275                 if (!min || (delta < min)) {
 276                         expires = next->expires;
 277                         min = delta;
 278                         type = i;
 279                 }
 280         }
 281         if (min == 0)
 282                 return 0;
 283
 284         if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
 285                 __pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
 286                 return -EBUSY;
 287         }
 288
 289         trace_alarmtimer_suspend(expires, type);
 290
 291         /* Setup an rtc timer to fire that far in the future */
 292         rtc_timer_cancel(rtc, &rtctimer);
 293         rtc_read_time(rtc, &tm);
 294         now = rtc_tm_to_ktime(tm);
 295         now = ktime_add(now, min);
 296
 297         /* Set alarm, if in the past reject suspend briefly to handle */
 298         ret = rtc_timer_start(rtc, &rtctimer, now, 0);
 299         if (ret < 0)
 300                 __pm_wakeup_event(ws, MSEC_PER_SEC);
 301         return ret;
 302 }
 303
 304 static int alarmtimer_resume(struct device *dev)
 305 {
 306         struct rtc_device *rtc;
 307
 308         rtc = alarmtimer_get_rtcdev();
 309         if (rtc)
 310                 rtc_timer_cancel(rtc, &rtctimer);
 311         return 0;
 312 }
 313
 314 #else
 315 static int alarmtimer_suspend(struct device *dev)
 316 {
 317         return 0;
 318 }
 319
 320 static int alarmtimer_resume(struct device *dev)
 321 {
 322         return 0;
 323 }
 324 #endif
 325
 326 static void
 327 __alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 328              enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 329 {
 330         timerqueue_init(&alarm->node);
 331         alarm->timer.function = alarmtimer_fired;
 332         alarm->function = function;
 333         alarm->type = type;
 334         alarm->state = ALARMTIMER_STATE_INACTIVE;
 335 }
 336
 337 /**
 338  * alarm_init - Initialize an alarm structure
 339  * @alarm: ptr to alarm to be initialized
 340  * @type: the type of the alarm
 341  * @function: callback that is run when the alarm fires
 342  */
 343 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 344                 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 345 {
 346         hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
 347                      HRTIMER_MODE_ABS);
 348         __alarm_init(alarm, type, function);
 349 }
 350 EXPORT_SYMBOL_GPL(alarm_init);
 351
 352 /**
 353  * alarm_start - Sets an absolute alarm to fire
 354  * @alarm: ptr to alarm to set
 355  * @start: time to run the alarm
 356  */
 357 void alarm_start(struct alarm *alarm, ktime_t start)
 358 {
 359         struct alarm_base *base = &alarm_bases[alarm->type];
 360         unsigned long flags;
 361
 362         spin_lock_irqsave(&base->lock, flags);
 363         alarm->node.expires = start;
 364         alarmtimer_enqueue(base, alarm);
 365         hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
 366         spin_unlock_irqrestore(&base->lock, flags);
 367
 368         trace_alarmtimer_start(alarm, base->gettime());
 369 }
 370 EXPORT_SYMBOL_GPL(alarm_start);
 371
 372 /**
 373  * alarm_start_relative - Sets a relative alarm to fire
 374  * @alarm: ptr to alarm to set
 375  * @start: time relative to now to run the alarm
 376  */
 377 void alarm_start_relative(struct alarm *alarm, ktime_t start)
 378 {
 379         struct alarm_base *base = &alarm_bases[alarm->type];
 380
 381         start = ktime_add_safe(start, base->gettime());
 382         alarm_start(alarm, start);
 383 }
 384 EXPORT_SYMBOL_GPL(alarm_start_relative);
 385
 386 void alarm_restart(struct alarm *alarm)
 387 {
 388         struct alarm_base *base = &alarm_bases[alarm->type];
 389         unsigned long flags;
 390
 391         spin_lock_irqsave(&base->lock, flags);
 392         hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 393         hrtimer_restart(&alarm->timer);
 394         alarmtimer_enqueue(base, alarm);
 395         spin_unlock_irqrestore(&base->lock, flags);
 396 }
 397 EXPORT_SYMBOL_GPL(alarm_restart);
 398
 399 /**
 400  * alarm_try_to_cancel - Tries to cancel an alarm timer
 401  * @alarm: ptr to alarm to be canceled
 402  *
 403  * Returns 1 if the timer was canceled, 0 if it was not running,
 404  * and -1 if the callback was running
 405  */
 406 int alarm_try_to_cancel(struct alarm *alarm)
 407 {
 408         struct alarm_base *base = &alarm_bases[alarm->type];
 409         unsigned long flags;
 410         int ret;
 411
 412         spin_lock_irqsave(&base->lock, flags);
 413         ret = hrtimer_try_to_cancel(&alarm->timer);
 414         if (ret >= 0)
 415                 alarmtimer_dequeue(base, alarm);
 416         spin_unlock_irqrestore(&base->lock, flags);
 417
 418         trace_alarmtimer_cancel(alarm, base->gettime());
 419         return ret;
 420 }
 421 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
 422
 423
 424 /**
 425  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
 426  * @alarm: ptr to alarm to be canceled
 427  *
 428  * Returns 1 if the timer was canceled, 0 if it was not active.
 429  */
 430 int alarm_cancel(struct alarm *alarm)
 431 {
 432         for (;;) {
 433                 int ret = alarm_try_to_cancel(alarm);
 434                 if (ret >= 0)
 435                         return ret;
 436                 cpu_relax();
 437         }
 438 }
 439 EXPORT_SYMBOL_GPL(alarm_cancel);
 440
 441
 442 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
 443 {
 444         u64 overrun = 1;
 445         ktime_t delta;
 446
 447         delta = ktime_sub(now, alarm->node.expires);
 448
 449         if (delta < 0)
 450                 return 0;
 451
 452         if (unlikely(delta >= interval)) {
 453                 s64 incr = ktime_to_ns(interval);
 454
 455                 overrun = ktime_divns(delta, incr);
 456
 457                 alarm->node.expires = ktime_add_ns(alarm->node.expires,
 458                                                         incr*overrun);
 459
 460                 if (alarm->node.expires > now)
 461                         return overrun;
 462                 /*
 463                  * This (and the ktime_add() below) is the
 464                  * correction for exact:
 465                  */
 466                 overrun++;
 467         }
 468
 469         alarm->node.expires = ktime_add_safe(alarm->node.expires, interval);
 470         return overrun;
 471 }
 472 EXPORT_SYMBOL_GPL(alarm_forward);
 473
 474 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 475 {
 476         struct alarm_base *base = &alarm_bases[alarm->type];
 477
 478         return alarm_forward(alarm, base->gettime(), interval);
 479 }
 480 EXPORT_SYMBOL_GPL(alarm_forward_now);
 481
 482 #ifdef CONFIG_POSIX_TIMERS
 483
 484 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 485 {
 486         struct alarm_base *base;
 487         unsigned long flags;
 488         ktime_t delta;
 489
 490         switch(type) {
 491         case ALARM_REALTIME:
 492                 base = &alarm_bases[ALARM_REALTIME];
 493                 type = ALARM_REALTIME_FREEZER;
 494                 break;
 495         case ALARM_BOOTTIME:
 496                 base = &alarm_bases[ALARM_BOOTTIME];
 497                 type = ALARM_BOOTTIME_FREEZER;
 498                 break;
 499         default:
 500                 WARN_ONCE(1, "Invalid alarm type: %d\n", type);
 501                 return;
 502         }
 503
 504         delta = ktime_sub(absexp, base->gettime());
 505
 506         spin_lock_irqsave(&freezer_delta_lock, flags);
 507         if (!freezer_delta || (delta < freezer_delta)) {
 508                 freezer_delta = delta;
 509                 freezer_expires = absexp;
 510                 freezer_alarmtype = type;
 511         }
 512         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 513 }
 514
 515 /**
 516  * clock2alarm - helper that converts from clockid to alarmtypes
 517  * @clockid: clockid.
 518  */
 519 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 520 {
 521         if (clockid == CLOCK_REALTIME_ALARM)
 522                 return ALARM_REALTIME;
 523         if (clockid == CLOCK_BOOTTIME_ALARM)
 524                 return ALARM_BOOTTIME;
 525         return -1;
 526 }
 527
 528 /**
 529  * alarm_handle_timer - Callback for posix timers
 530  * @alarm: alarm that fired
 531  *
 532  * Posix timer callback for expired alarm timers.
 533  */
 534 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 535                                                         ktime_t now)
 536 {
 537         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 538                                             it.alarm.alarmtimer);
 539         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
 540         unsigned long flags;
 541         int si_private = 0;
 542
 543         spin_lock_irqsave(&ptr->it_lock, flags);
 544
 545         ptr->it_active = 0;
 546         if (ptr->it_interval)
 547                 si_private = ++ptr->it_requeue_pending;
 548
 549         if (posix_timer_event(ptr, si_private) && ptr->it_interval) {
 550                 /*
 551                  * Handle ignored signals and rearm the timer. This will go
 552                  * away once we handle ignored signals proper.
 553                  */
 554                 ptr->it_overrun += alarm_forward_now(alarm, ptr->it_interval);
 555                 ++ptr->it_requeue_pending;
 556                 ptr->it_active = 1;
 557                 result = ALARMTIMER_RESTART;
 558         }
 559         spin_unlock_irqrestore(&ptr->it_lock, flags);
 560
 561         return result;
 562 }
 563
 564 /**
 565  * alarm_timer_rearm - Posix timer callback for rearming timer
 566  * @timr:       Pointer to the posixtimer data struct
 567  */
 568 static void alarm_timer_rearm(struct k_itimer *timr)
 569 {
 570         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 571
 572         timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
 573         alarm_start(alarm, alarm->node.expires);
 574 }
 575
 576 /**
 577  * alarm_timer_forward - Posix timer callback for forwarding timer
 578  * @timr:       Pointer to the posixtimer data struct
 579  * @now:        Current time to forward the timer against
 580  */
 581 static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
 582 {
 583         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 584
 585         return alarm_forward(alarm, timr->it_interval, now);
 586 }
 587
 588 /**
 589  * alarm_timer_remaining - Posix timer callback to retrieve remaining time
 590  * @timr:       Pointer to the posixtimer data struct
 591  * @now:        Current time to calculate against
 592  */
 593 static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
 594 {
 595         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 596
 597         return ktime_sub(now, alarm->node.expires);
 598 }
 599
 600 /**
 601  * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
 602  * @timr:       Pointer to the posixtimer data struct
 603  */
 604 static int alarm_timer_try_to_cancel(struct k_itimer *timr)
 605 {
 606         return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
 607 }
 608
 609 /**
 610  * alarm_timer_arm - Posix timer callback to arm a timer
 611  * @timr:       Pointer to the posixtimer data struct
 612  * @expires:    The new expiry time
 613  * @absolute:   Expiry value is absolute time
 614  * @sigev_none: Posix timer does not deliver signals
 615  */
 616 static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
 617                             bool absolute, bool sigev_none)
 618 {
 619         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 620         struct alarm_base *base = &alarm_bases[alarm->type];
 621
 622         if (!absolute)
 623                 expires = ktime_add_safe(expires, base->gettime());
 624         if (sigev_none)
 625                 alarm->node.expires = expires;
 626         else
 627                 alarm_start(&timr->it.alarm.alarmtimer, expires);
 628 }
 629
 630 /**
 631  * alarm_clock_getres - posix getres interface
 632  * @which_clock: clockid
 633  * @tp: timespec to fill
 634  *
 635  * Returns the granularity of underlying alarm base clock
 636  */
 637 static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 638 {
 639         if (!alarmtimer_get_rtcdev())
 640                 return -EINVAL;
 641
 642         tp->tv_sec = 0;
 643         tp->tv_nsec = hrtimer_resolution;
 644         return 0;
 645 }
 646
 647 /**
 648  * alarm_clock_get - posix clock_get interface
 649  * @which_clock: clockid
 650  * @tp: timespec to fill.
 651  *
 652  * Provides the underlying alarm base time.
 653  */
 654 static int alarm_clock_get(clockid_t which_clock, struct timespec64 *tp)
 655 {
 656         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 657
 658         if (!alarmtimer_get_rtcdev())
 659                 return -EINVAL;
 660
 661         *tp = ktime_to_timespec64(base->gettime());
 662         return 0;
 663 }
 664
 665 /**
 666  * alarm_timer_create - posix timer_create interface
 667  * @new_timer: k_itimer pointer to manage
 668  *
 669  * Initializes the k_itimer structure.
 670  */
 671 static int alarm_timer_create(struct k_itimer *new_timer)
 672 {
 673         enum  alarmtimer_type type;
 674
 675         if (!alarmtimer_get_rtcdev())
 676                 return -ENOTSUPP;
 677
 678         if (!capable(CAP_WAKE_ALARM))
 679                 return -EPERM;
 680
 681         type = clock2alarm(new_timer->it_clock);
 682         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 683         return 0;
 684 }
 685
 686 /**
 687  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 688  * @alarm: ptr to alarm that fired
 689  *
 690  * Wakes up the task that set the alarmtimer
 691  */
 692 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 693                                                                 ktime_t now)
 694 {
 695         struct task_struct *task = (struct task_struct *)alarm->data;
 696
 697         alarm->data = NULL;
 698         if (task)
 699                 wake_up_process(task);
 700         return ALARMTIMER_NORESTART;
 701 }
 702
 703 /**
 704  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 705  * @alarm: ptr to alarmtimer
 706  * @absexp: absolute expiration time
 707  *
 708  * Sets the alarm timer and sleeps until it is fired or interrupted.
 709  */
 710 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
 711                                 enum alarmtimer_type type)
 712 {
 713         struct restart_block *restart;
 714         alarm->data = (void *)current;
 715         do {
 716                 set_current_state(TASK_INTERRUPTIBLE);
 717                 alarm_start(alarm, absexp);
 718                 if (likely(alarm->data))
 719                         schedule();
 720
 721                 alarm_cancel(alarm);
 722         } while (alarm->data && !signal_pending(current));
 723
 724         __set_current_state(TASK_RUNNING);
 725
 726         destroy_hrtimer_on_stack(&alarm->timer);
 727
 728         if (!alarm->data)
 729                 return 0;
 730
 731         if (freezing(current))
 732                 alarmtimer_freezerset(absexp, type);
 733         restart = &current->restart_block;
 734         if (restart->nanosleep.type != TT_NONE) {
 735                 struct timespec64 rmt;
 736                 ktime_t rem;
 737
 738                 rem = ktime_sub(absexp, alarm_bases[type].gettime());
 739
 740                 if (rem <= 0)
 741                         return 0;
 742                 rmt = ktime_to_timespec64(rem);
 743
 744                 return nanosleep_copyout(restart, &rmt);
 745         }
 746         return -ERESTART_RESTARTBLOCK;
 747 }
 748
 749 static void
 750 alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
 751                     enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 752 {
 753         hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid,
 754                               HRTIMER_MODE_ABS);
 755         __alarm_init(alarm, type, function);
 756 }
 757
 758 /**
 759  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 760  * @restart: ptr to restart block
 761  *
 762  * Handles restarted clock_nanosleep calls
 763  */
 764 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 765 {
 766         enum  alarmtimer_type type = restart->nanosleep.clockid;
 767         ktime_t exp = restart->nanosleep.expires;
 768         struct alarm alarm;
 769
 770         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 771
 772         return alarmtimer_do_nsleep(&alarm, exp, type);
 773 }
 774
 775 /**
 776  * alarm_timer_nsleep - alarmtimer nanosleep
 777  * @which_clock: clockid
 778  * @flags: determins abstime or relative
 779  * @tsreq: requested sleep time (abs or rel)
 780  * @rmtp: remaining sleep time saved
 781  *
 782  * Handles clock_nanosleep calls against _ALARM clockids
 783  */
 784 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 785                               const struct timespec64 *tsreq)
 786 {
 787         enum  alarmtimer_type type = clock2alarm(which_clock);
 788         struct restart_block *restart = &current->restart_block;
 789         struct alarm alarm;
 790         ktime_t exp;
 791         int ret = 0;
 792
 793         if (!alarmtimer_get_rtcdev())
 794                 return -ENOTSUPP;
 795
 796         if (flags & ~TIMER_ABSTIME)
 797                 return -EINVAL;
 798
 799         if (!capable(CAP_WAKE_ALARM))
 800                 return -EPERM;
 801
 802         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 803
 804         exp = timespec64_to_ktime(*tsreq);
 805         /* Convert (if necessary) to absolute time */
 806         if (flags != TIMER_ABSTIME) {
 807                 ktime_t now = alarm_bases[type].gettime();
 808
 809                 exp = ktime_add_safe(now, exp);
 810         }
 811
 812         ret = alarmtimer_do_nsleep(&alarm, exp, type);
 813         if (ret != -ERESTART_RESTARTBLOCK)
 814                 return ret;
 815
 816         /* abs timers don't set remaining time or restart */
 817         if (flags == TIMER_ABSTIME)
 818                 return -ERESTARTNOHAND;
 819
 820         restart->fn = alarm_timer_nsleep_restart;
 821         restart->nanosleep.clockid = type;
 822         restart->nanosleep.expires = exp;
 823         return ret;
 824 }
 825
 826 const struct k_clock alarm_clock = {
 827         .clock_getres           = alarm_clock_getres,
 828         .clock_get              = alarm_clock_get,
 829         .timer_create           = alarm_timer_create,
 830         .timer_set              = common_timer_set,
 831         .timer_del              = common_timer_del,
 832         .timer_get              = common_timer_get,
 833         .timer_arm              = alarm_timer_arm,
 834         .timer_rearm            = alarm_timer_rearm,
 835         .timer_forward          = alarm_timer_forward,
 836         .timer_remaining        = alarm_timer_remaining,
 837         .timer_try_to_cancel    = alarm_timer_try_to_cancel,
 838         .nsleep                 = alarm_timer_nsleep,
 839 };
 840 #endif /* CONFIG_POSIX_TIMERS */
 841
 842
 843 /* Suspend hook structures */
 844 static const struct dev_pm_ops alarmtimer_pm_ops = {
 845         .suspend = alarmtimer_suspend,
 846         .resume = alarmtimer_resume,
 847 };
 848
 849 static struct platform_driver alarmtimer_driver = {
 850         .driver = {
 851                 .name = "alarmtimer",
 852                 .pm = &alarmtimer_pm_ops,
 853         }
 854 };
 855
 856 /**
 857  * alarmtimer_init - Initialize alarm timer code
 858  *
 859  * This function initializes the alarm bases and registers
 860  * the posix clock ids.
 861  */
 862 static int __init alarmtimer_init(void)
 863 {
 864         struct platform_device *pdev;
 865         int error = 0;
 866         int i;
 867
 868         alarmtimer_rtc_timer_init();
 869
 870         /* Initialize alarm bases */
 871         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 872         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
 873         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 874         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
 875         for (i = 0; i < ALARM_NUMTYPE; i++) {
 876                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 877                 spin_lock_init(&alarm_bases[i].lock);
 878         }
 879
 880         error = alarmtimer_rtc_interface_setup();
 881         if (error)
 882                 return error;
 883
 884         error = platform_driver_register(&alarmtimer_driver);
 885         if (error)
 886                 goto out_if;
 887
 888         pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
 889         if (IS_ERR(pdev)) {
 890                 error = PTR_ERR(pdev);
 891                 goto out_drv;
 892         }
 893         return 0;
 894
 895 out_drv:
 896         platform_driver_unregister(&alarmtimer_driver);
 897 out_if:
 898         alarmtimer_rtc_interface_remove();
 899         return error;
 900 }
 901 device_initcall(alarmtimer_init);