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 #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 (!rtc->ops->set_alarm)
  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 static u64 __alarm_forward_now(struct alarm *alarm, ktime_t interval, bool throttle)
 474 {
 475         struct alarm_base *base = &alarm_bases[alarm->type];
 476         ktime_t now = base->get_ktime();
 477
 478         if (IS_ENABLED(CONFIG_HIGH_RES_TIMERS) && throttle) {
 479                 /*
 480                  * Same issue as with posix_timer_fn(). Timers which are
 481                  * periodic but the signal is ignored can starve the system
 482                  * with a very small interval. The real fix which was
 483                  * promised in the context of posix_timer_fn() never
 484                  * materialized, but someone should really work on it.
 485                  *
 486                  * To prevent DOS fake @now to be 1 jiffie out which keeps
 487                  * the overrun accounting correct but creates an
 488                  * inconsistency vs. timer_gettime(2).
 489                  */
 490                 ktime_t kj = NSEC_PER_SEC / HZ;
 491
 492                 if (interval < kj)
 493                         now = ktime_add(now, kj);
 494         }
 495
 496         return alarm_forward(alarm, now, interval);
 497 }
 498
 499 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 500 {
 501         return __alarm_forward_now(alarm, interval, false);
 502 }
 503 EXPORT_SYMBOL_GPL(alarm_forward_now);
 504
 505 #ifdef CONFIG_POSIX_TIMERS
 506
 507 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 508 {
 509         struct alarm_base *base;
 510         unsigned long flags;
 511         ktime_t delta;
 512
 513         switch(type) {
 514         case ALARM_REALTIME:
 515                 base = &alarm_bases[ALARM_REALTIME];
 516                 type = ALARM_REALTIME_FREEZER;
 517                 break;
 518         case ALARM_BOOTTIME:
 519                 base = &alarm_bases[ALARM_BOOTTIME];
 520                 type = ALARM_BOOTTIME_FREEZER;
 521                 break;
 522         default:
 523                 WARN_ONCE(1, "Invalid alarm type: %d\n", type);
 524                 return;
 525         }
 526
 527         delta = ktime_sub(absexp, base->get_ktime());
 528
 529         spin_lock_irqsave(&freezer_delta_lock, flags);
 530         if (!freezer_delta || (delta < freezer_delta)) {
 531                 freezer_delta = delta;
 532                 freezer_expires = absexp;
 533                 freezer_alarmtype = type;
 534         }
 535         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 536 }
 537
 538 /**
 539  * clock2alarm - helper that converts from clockid to alarmtypes
 540  * @clockid: clockid.
 541  */
 542 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 543 {
 544         if (clockid == CLOCK_REALTIME_ALARM)
 545                 return ALARM_REALTIME;
 546         if (clockid == CLOCK_BOOTTIME_ALARM)
 547                 return ALARM_BOOTTIME;
 548         return -1;
 549 }
 550
 551 /**
 552  * alarm_handle_timer - Callback for posix timers
 553  * @alarm: alarm that fired
 554  *
 555  * Posix timer callback for expired alarm timers.
 556  */
 557 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 558                                                         ktime_t now)
 559 {
 560         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 561                                             it.alarm.alarmtimer);
 562         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
 563         unsigned long flags;
 564         int si_private = 0;
 565
 566         spin_lock_irqsave(&ptr->it_lock, flags);
 567
 568         ptr->it_active = 0;
 569         if (ptr->it_interval)
 570                 si_private = ++ptr->it_requeue_pending;
 571
 572         if (posix_timer_event(ptr, si_private) && ptr->it_interval) {
 573                 /*
 574                  * Handle ignored signals and rearm the timer. This will go
 575                  * away once we handle ignored signals proper. Ensure that
 576                  * small intervals cannot starve the system.
 577                  */
 578                 ptr->it_overrun += __alarm_forward_now(alarm, ptr->it_interval, true);
 579                 ++ptr->it_requeue_pending;
 580                 ptr->it_active = 1;
 581                 result = ALARMTIMER_RESTART;
 582         }
 583         spin_unlock_irqrestore(&ptr->it_lock, flags);
 584
 585         return result;
 586 }
 587
 588 /**
 589  * alarm_timer_rearm - Posix timer callback for rearming timer
 590  * @timr:       Pointer to the posixtimer data struct
 591  */
 592 static void alarm_timer_rearm(struct k_itimer *timr)
 593 {
 594         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 595
 596         timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
 597         alarm_start(alarm, alarm->node.expires);
 598 }
 599
 600 /**
 601  * alarm_timer_forward - Posix timer callback for forwarding timer
 602  * @timr:       Pointer to the posixtimer data struct
 603  * @now:        Current time to forward the timer against
 604  */
 605 static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
 606 {
 607         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 608
 609         return alarm_forward(alarm, timr->it_interval, now);
 610 }
 611
 612 /**
 613  * alarm_timer_remaining - Posix timer callback to retrieve remaining time
 614  * @timr:       Pointer to the posixtimer data struct
 615  * @now:        Current time to calculate against
 616  */
 617 static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
 618 {
 619         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 620
 621         return ktime_sub(alarm->node.expires, now);
 622 }
 623
 624 /**
 625  * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
 626  * @timr:       Pointer to the posixtimer data struct
 627  */
 628 static int alarm_timer_try_to_cancel(struct k_itimer *timr)
 629 {
 630         return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
 631 }
 632
 633 /**
 634  * alarm_timer_wait_running - Posix timer callback to wait for a timer
 635  * @timr:       Pointer to the posixtimer data struct
 636  *
 637  * Called from the core code when timer cancel detected that the callback
 638  * is running. @timr is unlocked and rcu read lock is held to prevent it
 639  * from being freed.
 640  */
 641 static void alarm_timer_wait_running(struct k_itimer *timr)
 642 {
 643         hrtimer_cancel_wait_running(&timr->it.alarm.alarmtimer.timer);
 644 }
 645
 646 /**
 647  * alarm_timer_arm - Posix timer callback to arm a timer
 648  * @timr:       Pointer to the posixtimer data struct
 649  * @expires:    The new expiry time
 650  * @absolute:   Expiry value is absolute time
 651  * @sigev_none: Posix timer does not deliver signals
 652  */
 653 static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
 654                             bool absolute, bool sigev_none)
 655 {
 656         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 657         struct alarm_base *base = &alarm_bases[alarm->type];
 658
 659         if (!absolute)
 660                 expires = ktime_add_safe(expires, base->get_ktime());
 661         if (sigev_none)
 662                 alarm->node.expires = expires;
 663         else
 664                 alarm_start(&timr->it.alarm.alarmtimer, expires);
 665 }
 666
 667 /**
 668  * alarm_clock_getres - posix getres interface
 669  * @which_clock: clockid
 670  * @tp: timespec to fill
 671  *
 672  * Returns the granularity of underlying alarm base clock
 673  */
 674 static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 675 {
 676         if (!alarmtimer_get_rtcdev())
 677                 return -EINVAL;
 678
 679         tp->tv_sec = 0;
 680         tp->tv_nsec = hrtimer_resolution;
 681         return 0;
 682 }
 683
 684 /**
 685  * alarm_clock_get_timespec - posix clock_get_timespec interface
 686  * @which_clock: clockid
 687  * @tp: timespec to fill.
 688  *
 689  * Provides the underlying alarm base time in a tasks time namespace.
 690  */
 691 static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 692 {
 693         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 694
 695         if (!alarmtimer_get_rtcdev())
 696                 return -EINVAL;
 697
 698         base->get_timespec(tp);
 699
 700         return 0;
 701 }
 702
 703 /**
 704  * alarm_clock_get_ktime - posix clock_get_ktime interface
 705  * @which_clock: clockid
 706  *
 707  * Provides the underlying alarm base time in the root namespace.
 708  */
 709 static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
 710 {
 711         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 712
 713         if (!alarmtimer_get_rtcdev())
 714                 return -EINVAL;
 715
 716         return base->get_ktime();
 717 }
 718
 719 /**
 720  * alarm_timer_create - posix timer_create interface
 721  * @new_timer: k_itimer pointer to manage
 722  *
 723  * Initializes the k_itimer structure.
 724  */
 725 static int alarm_timer_create(struct k_itimer *new_timer)
 726 {
 727         enum  alarmtimer_type type;
 728
 729         if (!alarmtimer_get_rtcdev())
 730                 return -EOPNOTSUPP;
 731
 732         if (!capable(CAP_WAKE_ALARM))
 733                 return -EPERM;
 734
 735         type = clock2alarm(new_timer->it_clock);
 736         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 737         return 0;
 738 }
 739
 740 /**
 741  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 742  * @alarm: ptr to alarm that fired
 743  *
 744  * Wakes up the task that set the alarmtimer
 745  */
 746 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 747                                                                 ktime_t now)
 748 {
 749         struct task_struct *task = (struct task_struct *)alarm->data;
 750
 751         alarm->data = NULL;
 752         if (task)
 753                 wake_up_process(task);
 754         return ALARMTIMER_NORESTART;
 755 }
 756
 757 /**
 758  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 759  * @alarm: ptr to alarmtimer
 760  * @absexp: absolute expiration time
 761  *
 762  * Sets the alarm timer and sleeps until it is fired or interrupted.
 763  */
 764 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
 765                                 enum alarmtimer_type type)
 766 {
 767         struct restart_block *restart;
 768         alarm->data = (void *)current;
 769         do {
 770                 set_current_state(TASK_INTERRUPTIBLE);
 771                 alarm_start(alarm, absexp);
 772                 if (likely(alarm->data))
 773                         schedule();
 774
 775                 alarm_cancel(alarm);
 776         } while (alarm->data && !signal_pending(current));
 777
 778         __set_current_state(TASK_RUNNING);
 779
 780         destroy_hrtimer_on_stack(&alarm->timer);
 781
 782         if (!alarm->data)
 783                 return 0;
 784
 785         if (freezing(current))
 786                 alarmtimer_freezerset(absexp, type);
 787         restart = &current->restart_block;
 788         if (restart->nanosleep.type != TT_NONE) {
 789                 struct timespec64 rmt;
 790                 ktime_t rem;
 791
 792                 rem = ktime_sub(absexp, alarm_bases[type].get_ktime());
 793
 794                 if (rem <= 0)
 795                         return 0;
 796                 rmt = ktime_to_timespec64(rem);
 797
 798                 return nanosleep_copyout(restart, &rmt);
 799         }
 800         return -ERESTART_RESTARTBLOCK;
 801 }
 802
 803 static void
 804 alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
 805                     enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 806 {
 807         hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid,
 808                               HRTIMER_MODE_ABS);
 809         __alarm_init(alarm, type, function);
 810 }
 811
 812 /**
 813  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 814  * @restart: ptr to restart block
 815  *
 816  * Handles restarted clock_nanosleep calls
 817  */
 818 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 819 {
 820         enum  alarmtimer_type type = restart->nanosleep.clockid;
 821         ktime_t exp = restart->nanosleep.expires;
 822         struct alarm alarm;
 823
 824         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 825
 826         return alarmtimer_do_nsleep(&alarm, exp, type);
 827 }
 828
 829 /**
 830  * alarm_timer_nsleep - alarmtimer nanosleep
 831  * @which_clock: clockid
 832  * @flags: determins abstime or relative
 833  * @tsreq: requested sleep time (abs or rel)
 834  * @rmtp: remaining sleep time saved
 835  *
 836  * Handles clock_nanosleep calls against _ALARM clockids
 837  */
 838 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 839                               const struct timespec64 *tsreq)
 840 {
 841         enum  alarmtimer_type type = clock2alarm(which_clock);
 842         struct restart_block *restart = &current->restart_block;
 843         struct alarm alarm;
 844         ktime_t exp;
 845         int ret = 0;
 846
 847         if (!alarmtimer_get_rtcdev())
 848                 return -EOPNOTSUPP;
 849
 850         if (flags & ~TIMER_ABSTIME)
 851                 return -EINVAL;
 852
 853         if (!capable(CAP_WAKE_ALARM))
 854                 return -EPERM;
 855
 856         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 857
 858         exp = timespec64_to_ktime(*tsreq);
 859         /* Convert (if necessary) to absolute time */
 860         if (flags != TIMER_ABSTIME) {
 861                 ktime_t now = alarm_bases[type].get_ktime();
 862
 863                 exp = ktime_add_safe(now, exp);
 864         } else {
 865                 exp = timens_ktime_to_host(which_clock, exp);
 866         }
 867
 868         ret = alarmtimer_do_nsleep(&alarm, exp, type);
 869         if (ret != -ERESTART_RESTARTBLOCK)
 870                 return ret;
 871
 872         /* abs timers don't set remaining time or restart */
 873         if (flags == TIMER_ABSTIME)
 874                 return -ERESTARTNOHAND;
 875
 876         restart->nanosleep.clockid = type;
 877         restart->nanosleep.expires = exp;
 878         set_restart_fn(restart, alarm_timer_nsleep_restart);
 879         return ret;
 880 }
 881
 882 const struct k_clock alarm_clock = {
 883         .clock_getres           = alarm_clock_getres,
 884         .clock_get_ktime        = alarm_clock_get_ktime,
 885         .clock_get_timespec     = alarm_clock_get_timespec,
 886         .timer_create           = alarm_timer_create,
 887         .timer_set              = common_timer_set,
 888         .timer_del              = common_timer_del,
 889         .timer_get              = common_timer_get,
 890         .timer_arm              = alarm_timer_arm,
 891         .timer_rearm            = alarm_timer_rearm,
 892         .timer_forward          = alarm_timer_forward,
 893         .timer_remaining        = alarm_timer_remaining,
 894         .timer_try_to_cancel    = alarm_timer_try_to_cancel,
 895         .timer_wait_running     = alarm_timer_wait_running,
 896         .nsleep                 = alarm_timer_nsleep,
 897 };
 898 #endif /* CONFIG_POSIX_TIMERS */
 899
 900
 901 /* Suspend hook structures */
 902 static const struct dev_pm_ops alarmtimer_pm_ops = {
 903         .suspend = alarmtimer_suspend,
 904         .resume = alarmtimer_resume,
 905 };
 906
 907 static struct platform_driver alarmtimer_driver = {
 908         .driver = {
 909                 .name = "alarmtimer",
 910                 .pm = &alarmtimer_pm_ops,
 911         }
 912 };
 913
 914 static void get_boottime_timespec(struct timespec64 *tp)
 915 {
 916         ktime_get_boottime_ts64(tp);
 917         timens_add_boottime(tp);
 918 }
 919
 920 /**
 921  * alarmtimer_init - Initialize alarm timer code
 922  *
 923  * This function initializes the alarm bases and registers
 924  * the posix clock ids.
 925  */
 926 static int __init alarmtimer_init(void)
 927 {
 928         int error;
 929         int i;
 930
 931         alarmtimer_rtc_timer_init();
 932
 933         /* Initialize alarm bases */
 934         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 935         alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
 936         alarm_bases[ALARM_REALTIME].get_timespec = ktime_get_real_ts64;
 937         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 938         alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
 939         alarm_bases[ALARM_BOOTTIME].get_timespec = get_boottime_timespec;
 940         for (i = 0; i < ALARM_NUMTYPE; i++) {
 941                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 942                 spin_lock_init(&alarm_bases[i].lock);
 943         }
 944
 945         error = alarmtimer_rtc_interface_setup();
 946         if (error)
 947                 return error;
 948
 949         error = platform_driver_register(&alarmtimer_driver);
 950         if (error)
 951                 goto out_if;
 952
 953         return 0;
 954 out_if:
 955         alarmtimer_rtc_interface_remove();
 956         return error;
 957 }
 958 device_initcall(alarmtimer_init);