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 {
  86         unsigned long flags;
  87         struct rtc_device *rtc = to_rtc_device(dev);
  88         struct platform_device *pdev;
  89         int ret = 0;
  90
  91         if (rtcdev)
  92                 return -EBUSY;
  93
  94         if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
  95                 return -1;
  96         if (!device_may_wakeup(rtc->dev.parent))
  97                 return -1;
  98
  99         pdev = platform_device_register_data(dev, "alarmtimer",
 100                                              PLATFORM_DEVID_AUTO, NULL, 0);
 101         if (!IS_ERR(pdev))
 102                 device_init_wakeup(&pdev->dev, true);
 103
 104         spin_lock_irqsave(&rtcdev_lock, flags);
 105         if (!IS_ERR(pdev) && !rtcdev) {
 106                 if (!try_module_get(rtc->owner)) {
 107                         ret = -1;
 108                         goto unlock;
 109                 }
 110
 111                 rtcdev = rtc;
 112                 /* hold a reference so it doesn't go away */
 113                 get_device(dev);
 114                 pdev = NULL;
 115         } else {
 116                 ret = -1;
 117         }
 118 unlock:
 119         spin_unlock_irqrestore(&rtcdev_lock, flags);
 120
 121         platform_device_unregister(pdev);
 122
 123         return ret;
 124 }
 125
 126 static inline void alarmtimer_rtc_timer_init(void)
 127 {
 128         rtc_timer_init(&rtctimer, NULL, NULL);
 129 }
 130
 131 static struct class_interface alarmtimer_rtc_interface = {
 132         .add_dev = &alarmtimer_rtc_add_device,
 133 };
 134
 135 static int alarmtimer_rtc_interface_setup(void)
 136 {
 137         alarmtimer_rtc_interface.class = rtc_class;
 138         return class_interface_register(&alarmtimer_rtc_interface);
 139 }
 140 static void alarmtimer_rtc_interface_remove(void)
 141 {
 142         class_interface_unregister(&alarmtimer_rtc_interface);
 143 }
 144 #else
 145 static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
 146 static inline void alarmtimer_rtc_interface_remove(void) { }
 147 static inline void alarmtimer_rtc_timer_init(void) { }
 148 #endif
 149
 150 /**
 151  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
 152  * @base: pointer to the base where the timer is being run
 153  * @alarm: pointer to alarm being enqueued.
 154  *
 155  * Adds alarm to a alarm_base timerqueue
 156  *
 157  * Must hold base->lock when calling.
 158  */
 159 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
 160 {
 161         if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
 162                 timerqueue_del(&base->timerqueue, &alarm->node);
 163
 164         timerqueue_add(&base->timerqueue, &alarm->node);
 165         alarm->state |= ALARMTIMER_STATE_ENQUEUED;
 166 }
 167
 168 /**
 169  * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
 170  * @base: pointer to the base where the timer is running
 171  * @alarm: pointer to alarm being removed
 172  *
 173  * Removes alarm to a alarm_base timerqueue
 174  *
 175  * Must hold base->lock when calling.
 176  */
 177 static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
 178 {
 179         if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
 180                 return;
 181
 182         timerqueue_del(&base->timerqueue, &alarm->node);
 183         alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
 184 }
 185
 186
 187 /**
 188  * alarmtimer_fired - Handles alarm hrtimer being fired.
 189  * @timer: pointer to hrtimer being run
 190  *
 191  * When a alarm timer fires, this runs through the timerqueue to
 192  * see which alarms expired, and runs those. If there are more alarm
 193  * timers queued for the future, we set the hrtimer to fire when
 194  * the next future alarm timer expires.
 195  */
 196 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 197 {
 198         struct alarm *alarm = container_of(timer, struct alarm, timer);
 199         struct alarm_base *base = &alarm_bases[alarm->type];
 200         unsigned long flags;
 201         int ret = HRTIMER_NORESTART;
 202         int restart = ALARMTIMER_NORESTART;
 203
 204         spin_lock_irqsave(&base->lock, flags);
 205         alarmtimer_dequeue(base, alarm);
 206         spin_unlock_irqrestore(&base->lock, flags);
 207
 208         if (alarm->function)
 209                 restart = alarm->function(alarm, base->get_ktime());
 210
 211         spin_lock_irqsave(&base->lock, flags);
 212         if (restart != ALARMTIMER_NORESTART) {
 213                 hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 214                 alarmtimer_enqueue(base, alarm);
 215                 ret = HRTIMER_RESTART;
 216         }
 217         spin_unlock_irqrestore(&base->lock, flags);
 218
 219         trace_alarmtimer_fired(alarm, base->get_ktime());
 220         return ret;
 221
 222 }
 223
 224 ktime_t alarm_expires_remaining(const struct alarm *alarm)
 225 {
 226         struct alarm_base *base = &alarm_bases[alarm->type];
 227         return ktime_sub(alarm->node.expires, base->get_ktime());
 228 }
 229 EXPORT_SYMBOL_GPL(alarm_expires_remaining);
 230
 231 #ifdef CONFIG_RTC_CLASS
 232 /**
 233  * alarmtimer_suspend - Suspend time callback
 234  * @dev: unused
 235  *
 236  * When we are going into suspend, we look through the bases
 237  * to see which is the soonest timer to expire. We then
 238  * set an rtc timer to fire that far into the future, which
 239  * will wake us from suspend.
 240  */
 241 static int alarmtimer_suspend(struct device *dev)
 242 {
 243         ktime_t min, now, expires;
 244         int i, ret, type;
 245         struct rtc_device *rtc;
 246         unsigned long flags;
 247         struct rtc_time tm;
 248
 249         spin_lock_irqsave(&freezer_delta_lock, flags);
 250         min = freezer_delta;
 251         expires = freezer_expires;
 252         type = freezer_alarmtype;
 253         freezer_delta = 0;
 254         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 255
 256         rtc = alarmtimer_get_rtcdev();
 257         /* If we have no rtcdev, just return */
 258         if (!rtc)
 259                 return 0;
 260
 261         /* Find the soonest timer to expire*/
 262         for (i = 0; i < ALARM_NUMTYPE; i++) {
 263                 struct alarm_base *base = &alarm_bases[i];
 264                 struct timerqueue_node *next;
 265                 ktime_t delta;
 266
 267                 spin_lock_irqsave(&base->lock, flags);
 268                 next = timerqueue_getnext(&base->timerqueue);
 269                 spin_unlock_irqrestore(&base->lock, flags);
 270                 if (!next)
 271                         continue;
 272                 delta = ktime_sub(next->expires, base->get_ktime());
 273                 if (!min || (delta < min)) {
 274                         expires = next->expires;
 275                         min = delta;
 276                         type = i;
 277                 }
 278         }
 279         if (min == 0)
 280                 return 0;
 281
 282         if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
 283                 pm_wakeup_event(dev, 2 * MSEC_PER_SEC);
 284                 return -EBUSY;
 285         }
 286
 287         trace_alarmtimer_suspend(expires, type);
 288
 289         /* Setup an rtc timer to fire that far in the future */
 290         rtc_timer_cancel(rtc, &rtctimer);
 291         rtc_read_time(rtc, &tm);
 292         now = rtc_tm_to_ktime(tm);
 293         now = ktime_add(now, min);
 294
 295         /* Set alarm, if in the past reject suspend briefly to handle */
 296         ret = rtc_timer_start(rtc, &rtctimer, now, 0);
 297         if (ret < 0)
 298                 pm_wakeup_event(dev, MSEC_PER_SEC);
 299         return ret;
 300 }
 301
 302 static int alarmtimer_resume(struct device *dev)
 303 {
 304         struct rtc_device *rtc;
 305
 306         rtc = alarmtimer_get_rtcdev();
 307         if (rtc)
 308                 rtc_timer_cancel(rtc, &rtctimer);
 309         return 0;
 310 }
 311
 312 #else
 313 static int alarmtimer_suspend(struct device *dev)
 314 {
 315         return 0;
 316 }
 317
 318 static int alarmtimer_resume(struct device *dev)
 319 {
 320         return 0;
 321 }
 322 #endif
 323
 324 static void
 325 __alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 326              enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 327 {
 328         timerqueue_init(&alarm->node);
 329         alarm->timer.function = alarmtimer_fired;
 330         alarm->function = function;
 331         alarm->type = type;
 332         alarm->state = ALARMTIMER_STATE_INACTIVE;
 333 }
 334
 335 /**
 336  * alarm_init - Initialize an alarm structure
 337  * @alarm: ptr to alarm to be initialized
 338  * @type: the type of the alarm
 339  * @function: callback that is run when the alarm fires
 340  */
 341 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 342                 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 343 {
 344         hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
 345                      HRTIMER_MODE_ABS);
 346         __alarm_init(alarm, type, function);
 347 }
 348 EXPORT_SYMBOL_GPL(alarm_init);
 349
 350 /**
 351  * alarm_start - Sets an absolute alarm to fire
 352  * @alarm: ptr to alarm to set
 353  * @start: time to run the alarm
 354  */
 355 void alarm_start(struct alarm *alarm, ktime_t start)
 356 {
 357         struct alarm_base *base = &alarm_bases[alarm->type];
 358         unsigned long flags;
 359
 360         spin_lock_irqsave(&base->lock, flags);
 361         alarm->node.expires = start;
 362         alarmtimer_enqueue(base, alarm);
 363         hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
 364         spin_unlock_irqrestore(&base->lock, flags);
 365
 366         trace_alarmtimer_start(alarm, base->get_ktime());
 367 }
 368 EXPORT_SYMBOL_GPL(alarm_start);
 369
 370 /**
 371  * alarm_start_relative - Sets a relative alarm to fire
 372  * @alarm: ptr to alarm to set
 373  * @start: time relative to now to run the alarm
 374  */
 375 void alarm_start_relative(struct alarm *alarm, ktime_t start)
 376 {
 377         struct alarm_base *base = &alarm_bases[alarm->type];
 378
 379         start = ktime_add_safe(start, base->get_ktime());
 380         alarm_start(alarm, start);
 381 }
 382 EXPORT_SYMBOL_GPL(alarm_start_relative);
 383
 384 void alarm_restart(struct alarm *alarm)
 385 {
 386         struct alarm_base *base = &alarm_bases[alarm->type];
 387         unsigned long flags;
 388
 389         spin_lock_irqsave(&base->lock, flags);
 390         hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 391         hrtimer_restart(&alarm->timer);
 392         alarmtimer_enqueue(base, alarm);
 393         spin_unlock_irqrestore(&base->lock, flags);
 394 }
 395 EXPORT_SYMBOL_GPL(alarm_restart);
 396
 397 /**
 398  * alarm_try_to_cancel - Tries to cancel an alarm timer
 399  * @alarm: ptr to alarm to be canceled
 400  *
 401  * Returns 1 if the timer was canceled, 0 if it was not running,
 402  * and -1 if the callback was running
 403  */
 404 int alarm_try_to_cancel(struct alarm *alarm)
 405 {
 406         struct alarm_base *base = &alarm_bases[alarm->type];
 407         unsigned long flags;
 408         int ret;
 409
 410         spin_lock_irqsave(&base->lock, flags);
 411         ret = hrtimer_try_to_cancel(&alarm->timer);
 412         if (ret >= 0)
 413                 alarmtimer_dequeue(base, alarm);
 414         spin_unlock_irqrestore(&base->lock, flags);
 415
 416         trace_alarmtimer_cancel(alarm, base->get_ktime());
 417         return ret;
 418 }
 419 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
 420
 421
 422 /**
 423  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
 424  * @alarm: ptr to alarm to be canceled
 425  *
 426  * Returns 1 if the timer was canceled, 0 if it was not active.
 427  */
 428 int alarm_cancel(struct alarm *alarm)
 429 {
 430         for (;;) {
 431                 int ret = alarm_try_to_cancel(alarm);
 432                 if (ret >= 0)
 433                         return ret;
 434                 hrtimer_cancel_wait_running(&alarm->timer);
 435         }
 436 }
 437 EXPORT_SYMBOL_GPL(alarm_cancel);
 438
 439
 440 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
 441 {
 442         u64 overrun = 1;
 443         ktime_t delta;
 444
 445         delta = ktime_sub(now, alarm->node.expires);
 446
 447         if (delta < 0)
 448                 return 0;
 449
 450         if (unlikely(delta >= interval)) {
 451                 s64 incr = ktime_to_ns(interval);
 452
 453                 overrun = ktime_divns(delta, incr);
 454
 455                 alarm->node.expires = ktime_add_ns(alarm->node.expires,
 456                                                         incr*overrun);
 457
 458                 if (alarm->node.expires > now)
 459                         return overrun;
 460                 /*
 461                  * This (and the ktime_add() below) is the
 462                  * correction for exact:
 463                  */
 464                 overrun++;
 465         }
 466
 467         alarm->node.expires = ktime_add_safe(alarm->node.expires, interval);
 468         return overrun;
 469 }
 470 EXPORT_SYMBOL_GPL(alarm_forward);
 471
 472 static u64 __alarm_forward_now(struct alarm *alarm, ktime_t interval, bool throttle)
 473 {
 474         struct alarm_base *base = &alarm_bases[alarm->type];
 475         ktime_t now = base->get_ktime();
 476
 477         if (IS_ENABLED(CONFIG_HIGH_RES_TIMERS) && throttle) {
 478                 /*
 479                  * Same issue as with posix_timer_fn(). Timers which are
 480                  * periodic but the signal is ignored can starve the system
 481                  * with a very small interval. The real fix which was
 482                  * promised in the context of posix_timer_fn() never
 483                  * materialized, but someone should really work on it.
 484                  *
 485                  * To prevent DOS fake @now to be 1 jiffie out which keeps
 486                  * the overrun accounting correct but creates an
 487                  * inconsistency vs. timer_gettime(2).
 488                  */
 489                 ktime_t kj = NSEC_PER_SEC / HZ;
 490
 491                 if (interval < kj)
 492                         now = ktime_add(now, kj);
 493         }
 494
 495         return alarm_forward(alarm, now, interval);
 496 }
 497
 498 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 499 {
 500         return __alarm_forward_now(alarm, interval, false);
 501 }
 502 EXPORT_SYMBOL_GPL(alarm_forward_now);
 503
 504 #ifdef CONFIG_POSIX_TIMERS
 505
 506 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 507 {
 508         struct alarm_base *base;
 509         unsigned long flags;
 510         ktime_t delta;
 511
 512         switch(type) {
 513         case ALARM_REALTIME:
 514                 base = &alarm_bases[ALARM_REALTIME];
 515                 type = ALARM_REALTIME_FREEZER;
 516                 break;
 517         case ALARM_BOOTTIME:
 518                 base = &alarm_bases[ALARM_BOOTTIME];
 519                 type = ALARM_BOOTTIME_FREEZER;
 520                 break;
 521         default:
 522                 WARN_ONCE(1, "Invalid alarm type: %d\n", type);
 523                 return;
 524         }
 525
 526         delta = ktime_sub(absexp, base->get_ktime());
 527
 528         spin_lock_irqsave(&freezer_delta_lock, flags);
 529         if (!freezer_delta || (delta < freezer_delta)) {
 530                 freezer_delta = delta;
 531                 freezer_expires = absexp;
 532                 freezer_alarmtype = type;
 533         }
 534         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 535 }
 536
 537 /**
 538  * clock2alarm - helper that converts from clockid to alarmtypes
 539  * @clockid: clockid.
 540  */
 541 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 542 {
 543         if (clockid == CLOCK_REALTIME_ALARM)
 544                 return ALARM_REALTIME;
 545         if (clockid == CLOCK_BOOTTIME_ALARM)
 546                 return ALARM_BOOTTIME;
 547         return -1;
 548 }
 549
 550 /**
 551  * alarm_handle_timer - Callback for posix timers
 552  * @alarm: alarm that fired
 553  * @now: time at the timer expiration
 554  *
 555  * Posix timer callback for expired alarm timers.
 556  *
 557  * Return: whether the timer is to be restarted
 558  */
 559 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 560                                                         ktime_t now)
 561 {
 562         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 563                                             it.alarm.alarmtimer);
 564         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
 565         unsigned long flags;
 566         int si_private = 0;
 567
 568         spin_lock_irqsave(&ptr->it_lock, flags);
 569
 570         ptr->it_active = 0;
 571         if (ptr->it_interval)
 572                 si_private = ++ptr->it_requeue_pending;
 573
 574         if (posix_timer_event(ptr, si_private) && ptr->it_interval) {
 575                 /*
 576                  * Handle ignored signals and rearm the timer. This will go
 577                  * away once we handle ignored signals proper. Ensure that
 578                  * small intervals cannot starve the system.
 579                  */
 580                 ptr->it_overrun += __alarm_forward_now(alarm, ptr->it_interval, true);
 581                 ++ptr->it_requeue_pending;
 582                 ptr->it_active = 1;
 583                 result = ALARMTIMER_RESTART;
 584         }
 585         spin_unlock_irqrestore(&ptr->it_lock, flags);
 586
 587         return result;
 588 }
 589
 590 /**
 591  * alarm_timer_rearm - Posix timer callback for rearming timer
 592  * @timr:       Pointer to the posixtimer data struct
 593  */
 594 static void alarm_timer_rearm(struct k_itimer *timr)
 595 {
 596         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 597
 598         timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
 599         alarm_start(alarm, alarm->node.expires);
 600 }
 601
 602 /**
 603  * alarm_timer_forward - Posix timer callback for forwarding timer
 604  * @timr:       Pointer to the posixtimer data struct
 605  * @now:        Current time to forward the timer against
 606  */
 607 static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
 608 {
 609         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 610
 611         return alarm_forward(alarm, timr->it_interval, now);
 612 }
 613
 614 /**
 615  * alarm_timer_remaining - Posix timer callback to retrieve remaining time
 616  * @timr:       Pointer to the posixtimer data struct
 617  * @now:        Current time to calculate against
 618  */
 619 static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
 620 {
 621         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 622
 623         return ktime_sub(alarm->node.expires, now);
 624 }
 625
 626 /**
 627  * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
 628  * @timr:       Pointer to the posixtimer data struct
 629  */
 630 static int alarm_timer_try_to_cancel(struct k_itimer *timr)
 631 {
 632         return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
 633 }
 634
 635 /**
 636  * alarm_timer_wait_running - Posix timer callback to wait for a timer
 637  * @timr:       Pointer to the posixtimer data struct
 638  *
 639  * Called from the core code when timer cancel detected that the callback
 640  * is running. @timr is unlocked and rcu read lock is held to prevent it
 641  * from being freed.
 642  */
 643 static void alarm_timer_wait_running(struct k_itimer *timr)
 644 {
 645         hrtimer_cancel_wait_running(&timr->it.alarm.alarmtimer.timer);
 646 }
 647
 648 /**
 649  * alarm_timer_arm - Posix timer callback to arm a timer
 650  * @timr:       Pointer to the posixtimer data struct
 651  * @expires:    The new expiry time
 652  * @absolute:   Expiry value is absolute time
 653  * @sigev_none: Posix timer does not deliver signals
 654  */
 655 static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
 656                             bool absolute, bool sigev_none)
 657 {
 658         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 659         struct alarm_base *base = &alarm_bases[alarm->type];
 660
 661         if (!absolute)
 662                 expires = ktime_add_safe(expires, base->get_ktime());
 663         if (sigev_none)
 664                 alarm->node.expires = expires;
 665         else
 666                 alarm_start(&timr->it.alarm.alarmtimer, expires);
 667 }
 668
 669 /**
 670  * alarm_clock_getres - posix getres interface
 671  * @which_clock: clockid
 672  * @tp: timespec to fill
 673  *
 674  * Returns the granularity of underlying alarm base clock
 675  */
 676 static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 677 {
 678         if (!alarmtimer_get_rtcdev())
 679                 return -EINVAL;
 680
 681         tp->tv_sec = 0;
 682         tp->tv_nsec = hrtimer_resolution;
 683         return 0;
 684 }
 685
 686 /**
 687  * alarm_clock_get_timespec - posix clock_get_timespec interface
 688  * @which_clock: clockid
 689  * @tp: timespec to fill.
 690  *
 691  * Provides the underlying alarm base time in a tasks time namespace.
 692  */
 693 static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 694 {
 695         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 696
 697         if (!alarmtimer_get_rtcdev())
 698                 return -EINVAL;
 699
 700         base->get_timespec(tp);
 701
 702         return 0;
 703 }
 704
 705 /**
 706  * alarm_clock_get_ktime - posix clock_get_ktime interface
 707  * @which_clock: clockid
 708  *
 709  * Provides the underlying alarm base time in the root namespace.
 710  */
 711 static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
 712 {
 713         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 714
 715         if (!alarmtimer_get_rtcdev())
 716                 return -EINVAL;
 717
 718         return base->get_ktime();
 719 }
 720
 721 /**
 722  * alarm_timer_create - posix timer_create interface
 723  * @new_timer: k_itimer pointer to manage
 724  *
 725  * Initializes the k_itimer structure.
 726  */
 727 static int alarm_timer_create(struct k_itimer *new_timer)
 728 {
 729         enum  alarmtimer_type type;
 730
 731         if (!alarmtimer_get_rtcdev())
 732                 return -EOPNOTSUPP;
 733
 734         if (!capable(CAP_WAKE_ALARM))
 735                 return -EPERM;
 736
 737         type = clock2alarm(new_timer->it_clock);
 738         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 739         return 0;
 740 }
 741
 742 /**
 743  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 744  * @alarm: ptr to alarm that fired
 745  * @now: time at the timer expiration
 746  *
 747  * Wakes up the task that set the alarmtimer
 748  *
 749  * Return: ALARMTIMER_NORESTART
 750  */
 751 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 752                                                                 ktime_t now)
 753 {
 754         struct task_struct *task = alarm->data;
 755
 756         alarm->data = NULL;
 757         if (task)
 758                 wake_up_process(task);
 759         return ALARMTIMER_NORESTART;
 760 }
 761
 762 /**
 763  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 764  * @alarm: ptr to alarmtimer
 765  * @absexp: absolute expiration time
 766  * @type: alarm type (BOOTTIME/REALTIME).
 767  *
 768  * Sets the alarm timer and sleeps until it is fired or interrupted.
 769  */
 770 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
 771                                 enum alarmtimer_type type)
 772 {
 773         struct restart_block *restart;
 774         alarm->data = (void *)current;
 775         do {
 776                 set_current_state(TASK_INTERRUPTIBLE);
 777                 alarm_start(alarm, absexp);
 778                 if (likely(alarm->data))
 779                         schedule();
 780
 781                 alarm_cancel(alarm);
 782         } while (alarm->data && !signal_pending(current));
 783
 784         __set_current_state(TASK_RUNNING);
 785
 786         destroy_hrtimer_on_stack(&alarm->timer);
 787
 788         if (!alarm->data)
 789                 return 0;
 790
 791         if (freezing(current))
 792                 alarmtimer_freezerset(absexp, type);
 793         restart = &current->restart_block;
 794         if (restart->nanosleep.type != TT_NONE) {
 795                 struct timespec64 rmt;
 796                 ktime_t rem;
 797
 798                 rem = ktime_sub(absexp, alarm_bases[type].get_ktime());
 799
 800                 if (rem <= 0)
 801                         return 0;
 802                 rmt = ktime_to_timespec64(rem);
 803
 804                 return nanosleep_copyout(restart, &rmt);
 805         }
 806         return -ERESTART_RESTARTBLOCK;
 807 }
 808
 809 static void
 810 alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
 811                     enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 812 {
 813         hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid,
 814                               HRTIMER_MODE_ABS);
 815         __alarm_init(alarm, type, function);
 816 }
 817
 818 /**
 819  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 820  * @restart: ptr to restart block
 821  *
 822  * Handles restarted clock_nanosleep calls
 823  */
 824 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 825 {
 826         enum  alarmtimer_type type = restart->nanosleep.clockid;
 827         ktime_t exp = restart->nanosleep.expires;
 828         struct alarm alarm;
 829
 830         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 831
 832         return alarmtimer_do_nsleep(&alarm, exp, type);
 833 }
 834
 835 /**
 836  * alarm_timer_nsleep - alarmtimer nanosleep
 837  * @which_clock: clockid
 838  * @flags: determines abstime or relative
 839  * @tsreq: requested sleep time (abs or rel)
 840  *
 841  * Handles clock_nanosleep calls against _ALARM clockids
 842  */
 843 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 844                               const struct timespec64 *tsreq)
 845 {
 846         enum  alarmtimer_type type = clock2alarm(which_clock);
 847         struct restart_block *restart = &current->restart_block;
 848         struct alarm alarm;
 849         ktime_t exp;
 850         int ret;
 851
 852         if (!alarmtimer_get_rtcdev())
 853                 return -EOPNOTSUPP;
 854
 855         if (flags & ~TIMER_ABSTIME)
 856                 return -EINVAL;
 857
 858         if (!capable(CAP_WAKE_ALARM))
 859                 return -EPERM;
 860
 861         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 862
 863         exp = timespec64_to_ktime(*tsreq);
 864         /* Convert (if necessary) to absolute time */
 865         if (flags != TIMER_ABSTIME) {
 866                 ktime_t now = alarm_bases[type].get_ktime();
 867
 868                 exp = ktime_add_safe(now, exp);
 869         } else {
 870                 exp = timens_ktime_to_host(which_clock, exp);
 871         }
 872
 873         ret = alarmtimer_do_nsleep(&alarm, exp, type);
 874         if (ret != -ERESTART_RESTARTBLOCK)
 875                 return ret;
 876
 877         /* abs timers don't set remaining time or restart */
 878         if (flags == TIMER_ABSTIME)
 879                 return -ERESTARTNOHAND;
 880
 881         restart->nanosleep.clockid = type;
 882         restart->nanosleep.expires = exp;
 883         set_restart_fn(restart, alarm_timer_nsleep_restart);
 884         return ret;
 885 }
 886
 887 const struct k_clock alarm_clock = {
 888         .clock_getres           = alarm_clock_getres,
 889         .clock_get_ktime        = alarm_clock_get_ktime,
 890         .clock_get_timespec     = alarm_clock_get_timespec,
 891         .timer_create           = alarm_timer_create,
 892         .timer_set              = common_timer_set,
 893         .timer_del              = common_timer_del,
 894         .timer_get              = common_timer_get,
 895         .timer_arm              = alarm_timer_arm,
 896         .timer_rearm            = alarm_timer_rearm,
 897         .timer_forward          = alarm_timer_forward,
 898         .timer_remaining        = alarm_timer_remaining,
 899         .timer_try_to_cancel    = alarm_timer_try_to_cancel,
 900         .timer_wait_running     = alarm_timer_wait_running,
 901         .nsleep                 = alarm_timer_nsleep,
 902 };
 903 #endif /* CONFIG_POSIX_TIMERS */
 904
 905
 906 /* Suspend hook structures */
 907 static const struct dev_pm_ops alarmtimer_pm_ops = {
 908         .suspend = alarmtimer_suspend,
 909         .resume = alarmtimer_resume,
 910 };
 911
 912 static struct platform_driver alarmtimer_driver = {
 913         .driver = {
 914                 .name = "alarmtimer",
 915                 .pm = &alarmtimer_pm_ops,
 916         }
 917 };
 918
 919 static void get_boottime_timespec(struct timespec64 *tp)
 920 {
 921         ktime_get_boottime_ts64(tp);
 922         timens_add_boottime(tp);
 923 }
 924
 925 /**
 926  * alarmtimer_init - Initialize alarm timer code
 927  *
 928  * This function initializes the alarm bases and registers
 929  * the posix clock ids.
 930  */
 931 static int __init alarmtimer_init(void)
 932 {
 933         int error;
 934         int i;
 935
 936         alarmtimer_rtc_timer_init();
 937
 938         /* Initialize alarm bases */
 939         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 940         alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
 941         alarm_bases[ALARM_REALTIME].get_timespec = ktime_get_real_ts64;
 942         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 943         alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
 944         alarm_bases[ALARM_BOOTTIME].get_timespec = get_boottime_timespec;
 945         for (i = 0; i < ALARM_NUMTYPE; i++) {
 946                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 947                 spin_lock_init(&alarm_bases[i].lock);
 948         }
 949
 950         error = alarmtimer_rtc_interface_setup();
 951         if (error)
 952                 return error;
 953
 954         error = platform_driver_register(&alarmtimer_driver);
 955         if (error)
 956                 goto out_if;
 957
 958         return 0;
 959 out_if:
 960         alarmtimer_rtc_interface_remove();
 961         return error;
 962 }
 963 device_initcall(alarmtimer_init);