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 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  * @now: time at the timer expiration
 555  *
 556  * Posix timer callback for expired alarm timers.
 557  *
 558  * Return: whether the timer is to be restarted
 559  */
 560 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 561                                                         ktime_t now)
 562 {
 563         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 564                                             it.alarm.alarmtimer);
 565         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
 566         unsigned long flags;
 567         int si_private = 0;
 568
 569         spin_lock_irqsave(&ptr->it_lock, flags);
 570
 571         ptr->it_active = 0;
 572         if (ptr->it_interval)
 573                 si_private = ++ptr->it_requeue_pending;
 574
 575         if (posix_timer_event(ptr, si_private) && ptr->it_interval) {
 576                 /*
 577                  * Handle ignored signals and rearm the timer. This will go
 578                  * away once we handle ignored signals proper. Ensure that
 579                  * small intervals cannot starve the system.
 580                  */
 581                 ptr->it_overrun += __alarm_forward_now(alarm, ptr->it_interval, true);
 582                 ++ptr->it_requeue_pending;
 583                 ptr->it_active = 1;
 584                 result = ALARMTIMER_RESTART;
 585         }
 586         spin_unlock_irqrestore(&ptr->it_lock, flags);
 587
 588         return result;
 589 }
 590
 591 /**
 592  * alarm_timer_rearm - Posix timer callback for rearming timer
 593  * @timr:       Pointer to the posixtimer data struct
 594  */
 595 static void alarm_timer_rearm(struct k_itimer *timr)
 596 {
 597         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 598
 599         timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
 600         alarm_start(alarm, alarm->node.expires);
 601 }
 602
 603 /**
 604  * alarm_timer_forward - Posix timer callback for forwarding timer
 605  * @timr:       Pointer to the posixtimer data struct
 606  * @now:        Current time to forward the timer against
 607  */
 608 static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
 609 {
 610         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 611
 612         return alarm_forward(alarm, timr->it_interval, now);
 613 }
 614
 615 /**
 616  * alarm_timer_remaining - Posix timer callback to retrieve remaining time
 617  * @timr:       Pointer to the posixtimer data struct
 618  * @now:        Current time to calculate against
 619  */
 620 static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
 621 {
 622         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 623
 624         return ktime_sub(alarm->node.expires, now);
 625 }
 626
 627 /**
 628  * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
 629  * @timr:       Pointer to the posixtimer data struct
 630  */
 631 static int alarm_timer_try_to_cancel(struct k_itimer *timr)
 632 {
 633         return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
 634 }
 635
 636 /**
 637  * alarm_timer_wait_running - Posix timer callback to wait for a timer
 638  * @timr:       Pointer to the posixtimer data struct
 639  *
 640  * Called from the core code when timer cancel detected that the callback
 641  * is running. @timr is unlocked and rcu read lock is held to prevent it
 642  * from being freed.
 643  */
 644 static void alarm_timer_wait_running(struct k_itimer *timr)
 645 {
 646         hrtimer_cancel_wait_running(&timr->it.alarm.alarmtimer.timer);
 647 }
 648
 649 /**
 650  * alarm_timer_arm - Posix timer callback to arm a timer
 651  * @timr:       Pointer to the posixtimer data struct
 652  * @expires:    The new expiry time
 653  * @absolute:   Expiry value is absolute time
 654  * @sigev_none: Posix timer does not deliver signals
 655  */
 656 static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
 657                             bool absolute, bool sigev_none)
 658 {
 659         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 660         struct alarm_base *base = &alarm_bases[alarm->type];
 661
 662         if (!absolute)
 663                 expires = ktime_add_safe(expires, base->get_ktime());
 664         if (sigev_none)
 665                 alarm->node.expires = expires;
 666         else
 667                 alarm_start(&timr->it.alarm.alarmtimer, expires);
 668 }
 669
 670 /**
 671  * alarm_clock_getres - posix getres interface
 672  * @which_clock: clockid
 673  * @tp: timespec to fill
 674  *
 675  * Returns the granularity of underlying alarm base clock
 676  */
 677 static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 678 {
 679         if (!alarmtimer_get_rtcdev())
 680                 return -EINVAL;
 681
 682         tp->tv_sec = 0;
 683         tp->tv_nsec = hrtimer_resolution;
 684         return 0;
 685 }
 686
 687 /**
 688  * alarm_clock_get_timespec - posix clock_get_timespec interface
 689  * @which_clock: clockid
 690  * @tp: timespec to fill.
 691  *
 692  * Provides the underlying alarm base time in a tasks time namespace.
 693  */
 694 static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 695 {
 696         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 697
 698         if (!alarmtimer_get_rtcdev())
 699                 return -EINVAL;
 700
 701         base->get_timespec(tp);
 702
 703         return 0;
 704 }
 705
 706 /**
 707  * alarm_clock_get_ktime - posix clock_get_ktime interface
 708  * @which_clock: clockid
 709  *
 710  * Provides the underlying alarm base time in the root namespace.
 711  */
 712 static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
 713 {
 714         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 715
 716         if (!alarmtimer_get_rtcdev())
 717                 return -EINVAL;
 718
 719         return base->get_ktime();
 720 }
 721
 722 /**
 723  * alarm_timer_create - posix timer_create interface
 724  * @new_timer: k_itimer pointer to manage
 725  *
 726  * Initializes the k_itimer structure.
 727  */
 728 static int alarm_timer_create(struct k_itimer *new_timer)
 729 {
 730         enum  alarmtimer_type type;
 731
 732         if (!alarmtimer_get_rtcdev())
 733                 return -EOPNOTSUPP;
 734
 735         if (!capable(CAP_WAKE_ALARM))
 736                 return -EPERM;
 737
 738         type = clock2alarm(new_timer->it_clock);
 739         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 740         return 0;
 741 }
 742
 743 /**
 744  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 745  * @alarm: ptr to alarm that fired
 746  * @now: time at the timer expiration
 747  *
 748  * Wakes up the task that set the alarmtimer
 749  *
 750  * Return: ALARMTIMER_NORESTART
 751  */
 752 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 753                                                                 ktime_t now)
 754 {
 755         struct task_struct *task = (struct task_struct *)alarm->data;
 756
 757         alarm->data = NULL;
 758         if (task)
 759                 wake_up_process(task);
 760         return ALARMTIMER_NORESTART;
 761 }
 762
 763 /**
 764  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 765  * @alarm: ptr to alarmtimer
 766  * @absexp: absolute expiration time
 767  * @type: alarm type (BOOTTIME/REALTIME).
 768  *
 769  * Sets the alarm timer and sleeps until it is fired or interrupted.
 770  */
 771 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
 772                                 enum alarmtimer_type type)
 773 {
 774         struct restart_block *restart;
 775         alarm->data = (void *)current;
 776         do {
 777                 set_current_state(TASK_INTERRUPTIBLE);
 778                 alarm_start(alarm, absexp);
 779                 if (likely(alarm->data))
 780                         schedule();
 781
 782                 alarm_cancel(alarm);
 783         } while (alarm->data && !signal_pending(current));
 784
 785         __set_current_state(TASK_RUNNING);
 786
 787         destroy_hrtimer_on_stack(&alarm->timer);
 788
 789         if (!alarm->data)
 790                 return 0;
 791
 792         if (freezing(current))
 793                 alarmtimer_freezerset(absexp, type);
 794         restart = &current->restart_block;
 795         if (restart->nanosleep.type != TT_NONE) {
 796                 struct timespec64 rmt;
 797                 ktime_t rem;
 798
 799                 rem = ktime_sub(absexp, alarm_bases[type].get_ktime());
 800
 801                 if (rem <= 0)
 802                         return 0;
 803                 rmt = ktime_to_timespec64(rem);
 804
 805                 return nanosleep_copyout(restart, &rmt);
 806         }
 807         return -ERESTART_RESTARTBLOCK;
 808 }
 809
 810 static void
 811 alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
 812                     enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 813 {
 814         hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid,
 815                               HRTIMER_MODE_ABS);
 816         __alarm_init(alarm, type, function);
 817 }
 818
 819 /**
 820  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 821  * @restart: ptr to restart block
 822  *
 823  * Handles restarted clock_nanosleep calls
 824  */
 825 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 826 {
 827         enum  alarmtimer_type type = restart->nanosleep.clockid;
 828         ktime_t exp = restart->nanosleep.expires;
 829         struct alarm alarm;
 830
 831         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 832
 833         return alarmtimer_do_nsleep(&alarm, exp, type);
 834 }
 835
 836 /**
 837  * alarm_timer_nsleep - alarmtimer nanosleep
 838  * @which_clock: clockid
 839  * @flags: determines abstime or relative
 840  * @tsreq: requested sleep time (abs or rel)
 841  *
 842  * Handles clock_nanosleep calls against _ALARM clockids
 843  */
 844 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 845                               const struct timespec64 *tsreq)
 846 {
 847         enum  alarmtimer_type type = clock2alarm(which_clock);
 848         struct restart_block *restart = &current->restart_block;
 849         struct alarm alarm;
 850         ktime_t exp;
 851         int ret = 0;
 852
 853         if (!alarmtimer_get_rtcdev())
 854                 return -EOPNOTSUPP;
 855
 856         if (flags & ~TIMER_ABSTIME)
 857                 return -EINVAL;
 858
 859         if (!capable(CAP_WAKE_ALARM))
 860                 return -EPERM;
 861
 862         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 863
 864         exp = timespec64_to_ktime(*tsreq);
 865         /* Convert (if necessary) to absolute time */
 866         if (flags != TIMER_ABSTIME) {
 867                 ktime_t now = alarm_bases[type].get_ktime();
 868
 869                 exp = ktime_add_safe(now, exp);
 870         } else {
 871                 exp = timens_ktime_to_host(which_clock, exp);
 872         }
 873
 874         ret = alarmtimer_do_nsleep(&alarm, exp, type);
 875         if (ret != -ERESTART_RESTARTBLOCK)
 876                 return ret;
 877
 878         /* abs timers don't set remaining time or restart */
 879         if (flags == TIMER_ABSTIME)
 880                 return -ERESTARTNOHAND;
 881
 882         restart->nanosleep.clockid = type;
 883         restart->nanosleep.expires = exp;
 884         set_restart_fn(restart, alarm_timer_nsleep_restart);
 885         return ret;
 886 }
 887
 888 const struct k_clock alarm_clock = {
 889         .clock_getres           = alarm_clock_getres,
 890         .clock_get_ktime        = alarm_clock_get_ktime,
 891         .clock_get_timespec     = alarm_clock_get_timespec,
 892         .timer_create           = alarm_timer_create,
 893         .timer_set              = common_timer_set,
 894         .timer_del              = common_timer_del,
 895         .timer_get              = common_timer_get,
 896         .timer_arm              = alarm_timer_arm,
 897         .timer_rearm            = alarm_timer_rearm,
 898         .timer_forward          = alarm_timer_forward,
 899         .timer_remaining        = alarm_timer_remaining,
 900         .timer_try_to_cancel    = alarm_timer_try_to_cancel,
 901         .timer_wait_running     = alarm_timer_wait_running,
 902         .nsleep                 = alarm_timer_nsleep,
 903 };
 904 #endif /* CONFIG_POSIX_TIMERS */
 905
 906
 907 /* Suspend hook structures */
 908 static const struct dev_pm_ops alarmtimer_pm_ops = {
 909         .suspend = alarmtimer_suspend,
 910         .resume = alarmtimer_resume,
 911 };
 912
 913 static struct platform_driver alarmtimer_driver = {
 914         .driver = {
 915                 .name = "alarmtimer",
 916                 .pm = &alarmtimer_pm_ops,
 917         }
 918 };
 919
 920 static void get_boottime_timespec(struct timespec64 *tp)
 921 {
 922         ktime_get_boottime_ts64(tp);
 923         timens_add_boottime(tp);
 924 }
 925
 926 /**
 927  * alarmtimer_init - Initialize alarm timer code
 928  *
 929  * This function initializes the alarm bases and registers
 930  * the posix clock ids.
 931  */
 932 static int __init alarmtimer_init(void)
 933 {
 934         int error;
 935         int i;
 936
 937         alarmtimer_rtc_timer_init();
 938
 939         /* Initialize alarm bases */
 940         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 941         alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
 942         alarm_bases[ALARM_REALTIME].get_timespec = ktime_get_real_ts64;
 943         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 944         alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
 945         alarm_bases[ALARM_BOOTTIME].get_timespec = get_boottime_timespec;
 946         for (i = 0; i < ALARM_NUMTYPE; i++) {
 947                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 948                 spin_lock_init(&alarm_bases[i].lock);
 949         }
 950
 951         error = alarmtimer_rtc_interface_setup();
 952         if (error)
 953                 return error;
 954
 955         error = platform_driver_register(&alarmtimer_driver);
 956         if (error)
 957                 goto out_if;
 958
 959         return 0;
 960 out_if:
 961         alarmtimer_rtc_interface_remove();
 962         return error;
 963 }
 964 device_initcall(alarmtimer_init);