kernel/time/alarmtimer.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Alarmtimer interface
   4  *
   5  * This interface provides a timer which is similar to 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 Corporation
  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 #include <linux/time_namespace.h>
  30
  31 #include "posix-timers.h"
  32
  33 #define CREATE_TRACE_POINTS
  34 #include <trace/events/alarmtimer.h>
  35
  36 /**
  37  * struct alarm_base - Alarm timer bases
  38  * @lock:               Lock for syncrhonized access to the base
  39  * @timerqueue:         Timerqueue head managing the list of events
  40  * @get_ktime:          Function to read the time correlating to the base
  41  * @get_timespec:       Function to read the namespace time correlating to the base
  42  * @base_clockid:       clockid for the base
  43  */
  44 static struct alarm_base {
  45         spinlock_t              lock;
  46         struct timerqueue_head  timerqueue;
  47         ktime_t                 (*get_ktime)(void);
  48         void                    (*get_timespec)(struct timespec64 *tp);
  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 /* rtc timer and device for setting alarm wakeups at suspend */
  62 static struct rtc_timer         rtctimer;
  63 static struct rtc_device        *rtcdev;
  64 static DEFINE_SPINLOCK(rtcdev_lock);
  65
  66 /**
  67  * alarmtimer_get_rtcdev - Return selected rtcdevice
  68  *
  69  * This function returns the rtc device to use for wakealarms.
  70  */
  71 struct rtc_device *alarmtimer_get_rtcdev(void)
  72 {
  73         unsigned long flags;
  74         struct rtc_device *ret;
  75
  76         spin_lock_irqsave(&rtcdev_lock, flags);
  77         ret = rtcdev;
  78         spin_unlock_irqrestore(&rtcdev_lock, flags);
  79
  80         return ret;
  81 }
  82 EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
  83
  84 static int alarmtimer_rtc_add_device(struct device *dev,
  85                                 struct class_interface *class_intf)
  86 {
  87         unsigned long flags;
  88         struct rtc_device *rtc = to_rtc_device(dev);
  89         struct platform_device *pdev;
  90         int ret = 0;
  91
  92         if (rtcdev)
  93                 return -EBUSY;
  94
  95         if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
  96                 return -1;
  97         if (!device_may_wakeup(rtc->dev.parent))
  98                 return -1;
  99
 100         pdev = platform_device_register_data(dev, "alarmtimer",
 101                                              PLATFORM_DEVID_AUTO, NULL, 0);
 102         if (!IS_ERR(pdev))
 103                 device_init_wakeup(&pdev->dev, true);
 104
 105         spin_lock_irqsave(&rtcdev_lock, flags);
 106         if (!IS_ERR(pdev) && !rtcdev) {
 107                 if (!try_module_get(rtc->owner)) {
 108                         ret = -1;
 109                         goto unlock;
 110                 }
 111
 112                 rtcdev = rtc;
 113                 /* hold a reference so it doesn't go away */
 114                 get_device(dev);
 115                 pdev = NULL;
 116         } else {
 117                 ret = -1;
 118         }
 119 unlock:
 120         spin_unlock_irqrestore(&rtcdev_lock, flags);
 121
 122         platform_device_unregister(pdev);
 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 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  * 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->get_ktime());
 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->get_ktime());
 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->get_ktime());
 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->get_ktime());
 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(dev, 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(dev, 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->get_ktime());
 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->get_ktime());
 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->get_ktime());
 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                 hrtimer_cancel_wait_running(&alarm->timer);
 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->get_ktime(), 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->get_ktime());
 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  * @now: time at the timer expiration
 531  *
 532  * Posix timer callback for expired alarm timers.
 533  *
 534  * Return: whether the timer is to be restarted
 535  */
 536 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 537                                                         ktime_t now)
 538 {
 539         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 540                                             it.alarm.alarmtimer);
 541         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
 542         unsigned long flags;
 543         int si_private = 0;
 544
 545         spin_lock_irqsave(&ptr->it_lock, flags);
 546
 547         ptr->it_active = 0;
 548         if (ptr->it_interval)
 549                 si_private = ++ptr->it_requeue_pending;
 550
 551         if (posix_timer_event(ptr, si_private) && ptr->it_interval) {
 552                 /*
 553                  * Handle ignored signals and rearm the timer. This will go
 554                  * away once we handle ignored signals proper.
 555                  */
 556                 ptr->it_overrun += alarm_forward_now(alarm, ptr->it_interval);
 557                 ++ptr->it_requeue_pending;
 558                 ptr->it_active = 1;
 559                 result = ALARMTIMER_RESTART;
 560         }
 561         spin_unlock_irqrestore(&ptr->it_lock, flags);
 562
 563         return result;
 564 }
 565
 566 /**
 567  * alarm_timer_rearm - Posix timer callback for rearming timer
 568  * @timr:       Pointer to the posixtimer data struct
 569  */
 570 static void alarm_timer_rearm(struct k_itimer *timr)
 571 {
 572         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 573
 574         timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
 575         alarm_start(alarm, alarm->node.expires);
 576 }
 577
 578 /**
 579  * alarm_timer_forward - Posix timer callback for forwarding timer
 580  * @timr:       Pointer to the posixtimer data struct
 581  * @now:        Current time to forward the timer against
 582  */
 583 static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
 584 {
 585         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 586
 587         return alarm_forward(alarm, timr->it_interval, now);
 588 }
 589
 590 /**
 591  * alarm_timer_remaining - Posix timer callback to retrieve remaining time
 592  * @timr:       Pointer to the posixtimer data struct
 593  * @now:        Current time to calculate against
 594  */
 595 static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
 596 {
 597         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 598
 599         return ktime_sub(alarm->node.expires, now);
 600 }
 601
 602 /**
 603  * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
 604  * @timr:       Pointer to the posixtimer data struct
 605  */
 606 static int alarm_timer_try_to_cancel(struct k_itimer *timr)
 607 {
 608         return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
 609 }
 610
 611 /**
 612  * alarm_timer_wait_running - Posix timer callback to wait for a timer
 613  * @timr:       Pointer to the posixtimer data struct
 614  *
 615  * Called from the core code when timer cancel detected that the callback
 616  * is running. @timr is unlocked and rcu read lock is held to prevent it
 617  * from being freed.
 618  */
 619 static void alarm_timer_wait_running(struct k_itimer *timr)
 620 {
 621         hrtimer_cancel_wait_running(&timr->it.alarm.alarmtimer.timer);
 622 }
 623
 624 /**
 625  * alarm_timer_arm - Posix timer callback to arm a timer
 626  * @timr:       Pointer to the posixtimer data struct
 627  * @expires:    The new expiry time
 628  * @absolute:   Expiry value is absolute time
 629  * @sigev_none: Posix timer does not deliver signals
 630  */
 631 static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
 632                             bool absolute, bool sigev_none)
 633 {
 634         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 635         struct alarm_base *base = &alarm_bases[alarm->type];
 636
 637         if (!absolute)
 638                 expires = ktime_add_safe(expires, base->get_ktime());
 639         if (sigev_none)
 640                 alarm->node.expires = expires;
 641         else
 642                 alarm_start(&timr->it.alarm.alarmtimer, expires);
 643 }
 644
 645 /**
 646  * alarm_clock_getres - posix getres interface
 647  * @which_clock: clockid
 648  * @tp: timespec to fill
 649  *
 650  * Returns the granularity of underlying alarm base clock
 651  */
 652 static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 653 {
 654         if (!alarmtimer_get_rtcdev())
 655                 return -EINVAL;
 656
 657         tp->tv_sec = 0;
 658         tp->tv_nsec = hrtimer_resolution;
 659         return 0;
 660 }
 661
 662 /**
 663  * alarm_clock_get_timespec - posix clock_get_timespec interface
 664  * @which_clock: clockid
 665  * @tp: timespec to fill.
 666  *
 667  * Provides the underlying alarm base time in a tasks time namespace.
 668  */
 669 static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 670 {
 671         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 672
 673         if (!alarmtimer_get_rtcdev())
 674                 return -EINVAL;
 675
 676         base->get_timespec(tp);
 677
 678         return 0;
 679 }
 680
 681 /**
 682  * alarm_clock_get_ktime - posix clock_get_ktime interface
 683  * @which_clock: clockid
 684  *
 685  * Provides the underlying alarm base time in the root namespace.
 686  */
 687 static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
 688 {
 689         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 690
 691         if (!alarmtimer_get_rtcdev())
 692                 return -EINVAL;
 693
 694         return base->get_ktime();
 695 }
 696
 697 /**
 698  * alarm_timer_create - posix timer_create interface
 699  * @new_timer: k_itimer pointer to manage
 700  *
 701  * Initializes the k_itimer structure.
 702  */
 703 static int alarm_timer_create(struct k_itimer *new_timer)
 704 {
 705         enum  alarmtimer_type type;
 706
 707         if (!alarmtimer_get_rtcdev())
 708                 return -EOPNOTSUPP;
 709
 710         if (!capable(CAP_WAKE_ALARM))
 711                 return -EPERM;
 712
 713         type = clock2alarm(new_timer->it_clock);
 714         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 715         return 0;
 716 }
 717
 718 /**
 719  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 720  * @alarm: ptr to alarm that fired
 721  * @now: time at the timer expiration
 722  *
 723  * Wakes up the task that set the alarmtimer
 724  *
 725  * Return: ALARMTIMER_NORESTART
 726  */
 727 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 728                                                                 ktime_t now)
 729 {
 730         struct task_struct *task = (struct task_struct *)alarm->data;
 731
 732         alarm->data = NULL;
 733         if (task)
 734                 wake_up_process(task);
 735         return ALARMTIMER_NORESTART;
 736 }
 737
 738 /**
 739  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 740  * @alarm: ptr to alarmtimer
 741  * @absexp: absolute expiration time
 742  * @type: alarm type (BOOTTIME/REALTIME).
 743  *
 744  * Sets the alarm timer and sleeps until it is fired or interrupted.
 745  */
 746 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
 747                                 enum alarmtimer_type type)
 748 {
 749         struct restart_block *restart;
 750         alarm->data = (void *)current;
 751         do {
 752                 set_current_state(TASK_INTERRUPTIBLE);
 753                 alarm_start(alarm, absexp);
 754                 if (likely(alarm->data))
 755                         schedule();
 756
 757                 alarm_cancel(alarm);
 758         } while (alarm->data && !signal_pending(current));
 759
 760         __set_current_state(TASK_RUNNING);
 761
 762         destroy_hrtimer_on_stack(&alarm->timer);
 763
 764         if (!alarm->data)
 765                 return 0;
 766
 767         if (freezing(current))
 768                 alarmtimer_freezerset(absexp, type);
 769         restart = &current->restart_block;
 770         if (restart->nanosleep.type != TT_NONE) {
 771                 struct timespec64 rmt;
 772                 ktime_t rem;
 773
 774                 rem = ktime_sub(absexp, alarm_bases[type].get_ktime());
 775
 776                 if (rem <= 0)
 777                         return 0;
 778                 rmt = ktime_to_timespec64(rem);
 779
 780                 return nanosleep_copyout(restart, &rmt);
 781         }
 782         return -ERESTART_RESTARTBLOCK;
 783 }
 784
 785 static void
 786 alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
 787                     enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 788 {
 789         hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid,
 790                               HRTIMER_MODE_ABS);
 791         __alarm_init(alarm, type, function);
 792 }
 793
 794 /**
 795  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 796  * @restart: ptr to restart block
 797  *
 798  * Handles restarted clock_nanosleep calls
 799  */
 800 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 801 {
 802         enum  alarmtimer_type type = restart->nanosleep.clockid;
 803         ktime_t exp = restart->nanosleep.expires;
 804         struct alarm alarm;
 805
 806         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 807
 808         return alarmtimer_do_nsleep(&alarm, exp, type);
 809 }
 810
 811 /**
 812  * alarm_timer_nsleep - alarmtimer nanosleep
 813  * @which_clock: clockid
 814  * @flags: determines abstime or relative
 815  * @tsreq: requested sleep time (abs or rel)
 816  *
 817  * Handles clock_nanosleep calls against _ALARM clockids
 818  */
 819 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 820                               const struct timespec64 *tsreq)
 821 {
 822         enum  alarmtimer_type type = clock2alarm(which_clock);
 823         struct restart_block *restart = &current->restart_block;
 824         struct alarm alarm;
 825         ktime_t exp;
 826         int ret = 0;
 827
 828         if (!alarmtimer_get_rtcdev())
 829                 return -EOPNOTSUPP;
 830
 831         if (flags & ~TIMER_ABSTIME)
 832                 return -EINVAL;
 833
 834         if (!capable(CAP_WAKE_ALARM))
 835                 return -EPERM;
 836
 837         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 838
 839         exp = timespec64_to_ktime(*tsreq);
 840         /* Convert (if necessary) to absolute time */
 841         if (flags != TIMER_ABSTIME) {
 842                 ktime_t now = alarm_bases[type].get_ktime();
 843
 844                 exp = ktime_add_safe(now, exp);
 845         } else {
 846                 exp = timens_ktime_to_host(which_clock, exp);
 847         }
 848
 849         ret = alarmtimer_do_nsleep(&alarm, exp, type);
 850         if (ret != -ERESTART_RESTARTBLOCK)
 851                 return ret;
 852
 853         /* abs timers don't set remaining time or restart */
 854         if (flags == TIMER_ABSTIME)
 855                 return -ERESTARTNOHAND;
 856
 857         restart->nanosleep.clockid = type;
 858         restart->nanosleep.expires = exp;
 859         set_restart_fn(restart, alarm_timer_nsleep_restart);
 860         return ret;
 861 }
 862
 863 const struct k_clock alarm_clock = {
 864         .clock_getres           = alarm_clock_getres,
 865         .clock_get_ktime        = alarm_clock_get_ktime,
 866         .clock_get_timespec     = alarm_clock_get_timespec,
 867         .timer_create           = alarm_timer_create,
 868         .timer_set              = common_timer_set,
 869         .timer_del              = common_timer_del,
 870         .timer_get              = common_timer_get,
 871         .timer_arm              = alarm_timer_arm,
 872         .timer_rearm            = alarm_timer_rearm,
 873         .timer_forward          = alarm_timer_forward,
 874         .timer_remaining        = alarm_timer_remaining,
 875         .timer_try_to_cancel    = alarm_timer_try_to_cancel,
 876         .timer_wait_running     = alarm_timer_wait_running,
 877         .nsleep                 = alarm_timer_nsleep,
 878 };
 879 #endif /* CONFIG_POSIX_TIMERS */
 880
 881
 882 /* Suspend hook structures */
 883 static const struct dev_pm_ops alarmtimer_pm_ops = {
 884         .suspend = alarmtimer_suspend,
 885         .resume = alarmtimer_resume,
 886 };
 887
 888 static struct platform_driver alarmtimer_driver = {
 889         .driver = {
 890                 .name = "alarmtimer",
 891                 .pm = &alarmtimer_pm_ops,
 892         }
 893 };
 894
 895 static void get_boottime_timespec(struct timespec64 *tp)
 896 {
 897         ktime_get_boottime_ts64(tp);
 898         timens_add_boottime(tp);
 899 }
 900
 901 /**
 902  * alarmtimer_init - Initialize alarm timer code
 903  *
 904  * This function initializes the alarm bases and registers
 905  * the posix clock ids.
 906  */
 907 static int __init alarmtimer_init(void)
 908 {
 909         int error;
 910         int i;
 911
 912         alarmtimer_rtc_timer_init();
 913
 914         /* Initialize alarm bases */
 915         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 916         alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
 917         alarm_bases[ALARM_REALTIME].get_timespec = ktime_get_real_ts64;
 918         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 919         alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
 920         alarm_bases[ALARM_BOOTTIME].get_timespec = get_boottime_timespec;
 921         for (i = 0; i < ALARM_NUMTYPE; i++) {
 922                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 923                 spin_lock_init(&alarm_bases[i].lock);
 924         }
 925
 926         error = alarmtimer_rtc_interface_setup();
 927         if (error)
 928                 return error;
 929
 930         error = platform_driver_register(&alarmtimer_driver);
 931         if (error)
 932                 goto out_if;
 933
 934         return 0;
 935 out_if:
 936         alarmtimer_rtc_interface_remove();
 937         return error;
 938 }
 939 device_initcall(alarmtimer_init);