kernel/time/alarmtimer.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Alarmtimer interface
   4  *
   5  * This interface provides a timer which is similarto hrtimers,
   6  * but triggers a RTC alarm if the box is suspend.
   7  *
   8  * This interface is influenced by the Android RTC Alarm timer
   9  * interface.
  10  *
  11  * Copyright (C) 2010 IBM Corperation
  12  *
  13  * Author: John Stultz <john.stultz@linaro.org>
  14  */
  15 #include <linux/time.h>
  16 #include <linux/hrtimer.h>
  17 #include <linux/timerqueue.h>
  18 #include <linux/rtc.h>
  19 #include <linux/sched/signal.h>
  20 #include <linux/sched/debug.h>
  21 #include <linux/alarmtimer.h>
  22 #include <linux/mutex.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/posix-timers.h>
  25 #include <linux/workqueue.h>
  26 #include <linux/freezer.h>
  27 #include <linux/compat.h>
  28 #include <linux/module.h>
  29
  30 #include "posix-timers.h"
  31
  32 #define CREATE_TRACE_POINTS
  33 #include <trace/events/alarmtimer.h>
  34
  35 /**
  36  * struct alarm_base - Alarm timer bases
  37  * @lock:               Lock for syncrhonized access to the base
  38  * @timerqueue:         Timerqueue head managing the list of events
  39  * @gettime:            Function to read the time correlating to the base
  40  * @base_clockid:       clockid for the base
  41  */
  42 static struct alarm_base {
  43         spinlock_t              lock;
  44         struct timerqueue_head  timerqueue;
  45         ktime_t                 (*gettime)(void);
  46         clockid_t               base_clockid;
  47 } alarm_bases[ALARM_NUMTYPE];
  48
  49 #if defined(CONFIG_POSIX_TIMERS) || defined(CONFIG_RTC_CLASS)
  50 /* freezer information to handle clock_nanosleep triggered wakeups */
  51 static enum alarmtimer_type freezer_alarmtype;
  52 static ktime_t freezer_expires;
  53 static ktime_t freezer_delta;
  54 static DEFINE_SPINLOCK(freezer_delta_lock);
  55 #endif
  56
  57 #ifdef CONFIG_RTC_CLASS
  58 static struct wakeup_source *ws;
  59
  60 /* rtc timer and device for setting alarm wakeups at suspend */
  61 static struct rtc_timer         rtctimer;
  62 static struct rtc_device        *rtcdev;
  63 static DEFINE_SPINLOCK(rtcdev_lock);
  64
  65 /**
  66  * alarmtimer_get_rtcdev - Return selected rtcdevice
  67  *
  68  * This function returns the rtc device to use for wakealarms.
  69  * If one has not already been chosen, it checks to see if a
  70  * functional rtc device is available.
  71  */
  72 struct rtc_device *alarmtimer_get_rtcdev(void)
  73 {
  74         unsigned long flags;
  75         struct rtc_device *ret;
  76
  77         spin_lock_irqsave(&rtcdev_lock, flags);
  78         ret = rtcdev;
  79         spin_unlock_irqrestore(&rtcdev_lock, flags);
  80
  81         return ret;
  82 }
  83 EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
  84
  85 static int alarmtimer_rtc_add_device(struct device *dev,
  86                                 struct class_interface *class_intf)
  87 {
  88         unsigned long flags;
  89         struct rtc_device *rtc = to_rtc_device(dev);
  90         struct wakeup_source *__ws;
  91         struct platform_device *pdev;
  92         int ret = 0;
  93
  94         if (rtcdev)
  95                 return -EBUSY;
  96
  97         if (!rtc->ops->set_alarm)
  98                 return -1;
  99         if (!device_may_wakeup(rtc->dev.parent))
 100                 return -1;
 101
 102         __ws = wakeup_source_register(dev, "alarmtimer");
 103         pdev = platform_device_register_data(dev, "alarmtimer",
 104                                              PLATFORM_DEVID_AUTO, NULL, 0);
 105
 106         spin_lock_irqsave(&rtcdev_lock, flags);
 107         if (__ws && !IS_ERR(pdev) && !rtcdev) {
 108                 if (!try_module_get(rtc->owner)) {
 109                         ret = -1;
 110                         goto unlock;
 111                 }
 112
 113                 rtcdev = rtc;
 114                 /* hold a reference so it doesn't go away */
 115                 get_device(dev);
 116                 ws = __ws;
 117                 __ws = NULL;
 118                 pdev = NULL;
 119         } else {
 120                 ret = -1;
 121         }
 122 unlock:
 123         spin_unlock_irqrestore(&rtcdev_lock, flags);
 124
 125         platform_device_unregister(pdev);
 126         wakeup_source_unregister(__ws);
 127
 128         return ret;
 129 }
 130
 131 static inline void alarmtimer_rtc_timer_init(void)
 132 {
 133         rtc_timer_init(&rtctimer, NULL, NULL);
 134 }
 135
 136 static struct class_interface alarmtimer_rtc_interface = {
 137         .add_dev = &alarmtimer_rtc_add_device,
 138 };
 139
 140 static int alarmtimer_rtc_interface_setup(void)
 141 {
 142         alarmtimer_rtc_interface.class = rtc_class;
 143         return class_interface_register(&alarmtimer_rtc_interface);
 144 }
 145 static void alarmtimer_rtc_interface_remove(void)
 146 {
 147         class_interface_unregister(&alarmtimer_rtc_interface);
 148 }
 149 #else
 150 struct rtc_device *alarmtimer_get_rtcdev(void)
 151 {
 152         return NULL;
 153 }
 154 #define rtcdev (NULL)
 155 static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
 156 static inline void alarmtimer_rtc_interface_remove(void) { }
 157 static inline void alarmtimer_rtc_timer_init(void) { }
 158 #endif
 159
 160 /**
 161  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
 162  * @base: pointer to the base where the timer is being run
 163  * @alarm: pointer to alarm being enqueued.
 164  *
 165  * Adds alarm to a alarm_base timerqueue
 166  *
 167  * Must hold base->lock when calling.
 168  */
 169 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
 170 {
 171         if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
 172                 timerqueue_del(&base->timerqueue, &alarm->node);
 173
 174         timerqueue_add(&base->timerqueue, &alarm->node);
 175         alarm->state |= ALARMTIMER_STATE_ENQUEUED;
 176 }
 177
 178 /**
 179  * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
 180  * @base: pointer to the base where the timer is running
 181  * @alarm: pointer to alarm being removed
 182  *
 183  * Removes alarm to a alarm_base timerqueue
 184  *
 185  * Must hold base->lock when calling.
 186  */
 187 static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
 188 {
 189         if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
 190                 return;
 191
 192         timerqueue_del(&base->timerqueue, &alarm->node);
 193         alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
 194 }
 195
 196
 197 /**
 198  * alarmtimer_fired - Handles alarm hrtimer being fired.
 199  * @timer: pointer to hrtimer being run
 200  *
 201  * When a alarm timer fires, this runs through the timerqueue to
 202  * see which alarms expired, and runs those. If there are more alarm
 203  * timers queued for the future, we set the hrtimer to fire when
 204  * when the next future alarm timer expires.
 205  */
 206 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 207 {
 208         struct alarm *alarm = container_of(timer, struct alarm, timer);
 209         struct alarm_base *base = &alarm_bases[alarm->type];
 210         unsigned long flags;
 211         int ret = HRTIMER_NORESTART;
 212         int restart = ALARMTIMER_NORESTART;
 213
 214         spin_lock_irqsave(&base->lock, flags);
 215         alarmtimer_dequeue(base, alarm);
 216         spin_unlock_irqrestore(&base->lock, flags);
 217
 218         if (alarm->function)
 219                 restart = alarm->function(alarm, base->gettime());
 220
 221         spin_lock_irqsave(&base->lock, flags);
 222         if (restart != ALARMTIMER_NORESTART) {
 223                 hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 224                 alarmtimer_enqueue(base, alarm);
 225                 ret = HRTIMER_RESTART;
 226         }
 227         spin_unlock_irqrestore(&base->lock, flags);
 228
 229         trace_alarmtimer_fired(alarm, base->gettime());
 230         return ret;
 231
 232 }
 233
 234 ktime_t alarm_expires_remaining(const struct alarm *alarm)
 235 {
 236         struct alarm_base *base = &alarm_bases[alarm->type];
 237         return ktime_sub(alarm->node.expires, base->gettime());
 238 }
 239 EXPORT_SYMBOL_GPL(alarm_expires_remaining);
 240
 241 #ifdef CONFIG_RTC_CLASS
 242 /**
 243  * alarmtimer_suspend - Suspend time callback
 244  * @dev: unused
 245  *
 246  * When we are going into suspend, we look through the bases
 247  * to see which is the soonest timer to expire. We then
 248  * set an rtc timer to fire that far into the future, which
 249  * will wake us from suspend.
 250  */
 251 static int alarmtimer_suspend(struct device *dev)
 252 {
 253         ktime_t min, now, expires;
 254         int i, ret, type;
 255         struct rtc_device *rtc;
 256         unsigned long flags;
 257         struct rtc_time tm;
 258
 259         spin_lock_irqsave(&freezer_delta_lock, flags);
 260         min = freezer_delta;
 261         expires = freezer_expires;
 262         type = freezer_alarmtype;
 263         freezer_delta = 0;
 264         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 265
 266         rtc = alarmtimer_get_rtcdev();
 267         /* If we have no rtcdev, just return */
 268         if (!rtc)
 269                 return 0;
 270
 271         /* Find the soonest timer to expire*/
 272         for (i = 0; i < ALARM_NUMTYPE; i++) {
 273                 struct alarm_base *base = &alarm_bases[i];
 274                 struct timerqueue_node *next;
 275                 ktime_t delta;
 276
 277                 spin_lock_irqsave(&base->lock, flags);
 278                 next = timerqueue_getnext(&base->timerqueue);
 279                 spin_unlock_irqrestore(&base->lock, flags);
 280                 if (!next)
 281                         continue;
 282                 delta = ktime_sub(next->expires, base->gettime());
 283                 if (!min || (delta < min)) {
 284                         expires = next->expires;
 285                         min = delta;
 286                         type = i;
 287                 }
 288         }
 289         if (min == 0)
 290                 return 0;
 291
 292         if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
 293                 __pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
 294                 return -EBUSY;
 295         }
 296
 297         trace_alarmtimer_suspend(expires, type);
 298
 299         /* Setup an rtc timer to fire that far in the future */
 300         rtc_timer_cancel(rtc, &rtctimer);
 301         rtc_read_time(rtc, &tm);
 302         now = rtc_tm_to_ktime(tm);
 303         now = ktime_add(now, min);
 304
 305         /* Set alarm, if in the past reject suspend briefly to handle */
 306         ret = rtc_timer_start(rtc, &rtctimer, now, 0);
 307         if (ret < 0)
 308                 __pm_wakeup_event(ws, MSEC_PER_SEC);
 309         return ret;
 310 }
 311
 312 static int alarmtimer_resume(struct device *dev)
 313 {
 314         struct rtc_device *rtc;
 315
 316         rtc = alarmtimer_get_rtcdev();
 317         if (rtc)
 318                 rtc_timer_cancel(rtc, &rtctimer);
 319         return 0;
 320 }
 321
 322 #else
 323 static int alarmtimer_suspend(struct device *dev)
 324 {
 325         return 0;
 326 }
 327
 328 static int alarmtimer_resume(struct device *dev)
 329 {
 330         return 0;
 331 }
 332 #endif
 333
 334 static void
 335 __alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 336              enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 337 {
 338         timerqueue_init(&alarm->node);
 339         alarm->timer.function = alarmtimer_fired;
 340         alarm->function = function;
 341         alarm->type = type;
 342         alarm->state = ALARMTIMER_STATE_INACTIVE;
 343 }
 344
 345 /**
 346  * alarm_init - Initialize an alarm structure
 347  * @alarm: ptr to alarm to be initialized
 348  * @type: the type of the alarm
 349  * @function: callback that is run when the alarm fires
 350  */
 351 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 352                 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 353 {
 354         hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
 355                      HRTIMER_MODE_ABS);
 356         __alarm_init(alarm, type, function);
 357 }
 358 EXPORT_SYMBOL_GPL(alarm_init);
 359
 360 /**
 361  * alarm_start - Sets an absolute alarm to fire
 362  * @alarm: ptr to alarm to set
 363  * @start: time to run the alarm
 364  */
 365 void alarm_start(struct alarm *alarm, ktime_t start)
 366 {
 367         struct alarm_base *base = &alarm_bases[alarm->type];
 368         unsigned long flags;
 369
 370         spin_lock_irqsave(&base->lock, flags);
 371         alarm->node.expires = start;
 372         alarmtimer_enqueue(base, alarm);
 373         hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
 374         spin_unlock_irqrestore(&base->lock, flags);
 375
 376         trace_alarmtimer_start(alarm, base->gettime());
 377 }
 378 EXPORT_SYMBOL_GPL(alarm_start);
 379
 380 /**
 381  * alarm_start_relative - Sets a relative alarm to fire
 382  * @alarm: ptr to alarm to set
 383  * @start: time relative to now to run the alarm
 384  */
 385 void alarm_start_relative(struct alarm *alarm, ktime_t start)
 386 {
 387         struct alarm_base *base = &alarm_bases[alarm->type];
 388
 389         start = ktime_add_safe(start, base->gettime());
 390         alarm_start(alarm, start);
 391 }
 392 EXPORT_SYMBOL_GPL(alarm_start_relative);
 393
 394 void alarm_restart(struct alarm *alarm)
 395 {
 396         struct alarm_base *base = &alarm_bases[alarm->type];
 397         unsigned long flags;
 398
 399         spin_lock_irqsave(&base->lock, flags);
 400         hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 401         hrtimer_restart(&alarm->timer);
 402         alarmtimer_enqueue(base, alarm);
 403         spin_unlock_irqrestore(&base->lock, flags);
 404 }
 405 EXPORT_SYMBOL_GPL(alarm_restart);
 406
 407 /**
 408  * alarm_try_to_cancel - Tries to cancel an alarm timer
 409  * @alarm: ptr to alarm to be canceled
 410  *
 411  * Returns 1 if the timer was canceled, 0 if it was not running,
 412  * and -1 if the callback was running
 413  */
 414 int alarm_try_to_cancel(struct alarm *alarm)
 415 {
 416         struct alarm_base *base = &alarm_bases[alarm->type];
 417         unsigned long flags;
 418         int ret;
 419
 420         spin_lock_irqsave(&base->lock, flags);
 421         ret = hrtimer_try_to_cancel(&alarm->timer);
 422         if (ret >= 0)
 423                 alarmtimer_dequeue(base, alarm);
 424         spin_unlock_irqrestore(&base->lock, flags);
 425
 426         trace_alarmtimer_cancel(alarm, base->gettime());
 427         return ret;
 428 }
 429 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
 430
 431
 432 /**
 433  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
 434  * @alarm: ptr to alarm to be canceled
 435  *
 436  * Returns 1 if the timer was canceled, 0 if it was not active.
 437  */
 438 int alarm_cancel(struct alarm *alarm)
 439 {
 440         for (;;) {
 441                 int ret = alarm_try_to_cancel(alarm);
 442                 if (ret >= 0)
 443                         return ret;
 444                 hrtimer_cancel_wait_running(&alarm->timer);
 445         }
 446 }
 447 EXPORT_SYMBOL_GPL(alarm_cancel);
 448
 449
 450 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
 451 {
 452         u64 overrun = 1;
 453         ktime_t delta;
 454
 455         delta = ktime_sub(now, alarm->node.expires);
 456
 457         if (delta < 0)
 458                 return 0;
 459
 460         if (unlikely(delta >= interval)) {
 461                 s64 incr = ktime_to_ns(interval);
 462
 463                 overrun = ktime_divns(delta, incr);
 464
 465                 alarm->node.expires = ktime_add_ns(alarm->node.expires,
 466                                                         incr*overrun);
 467
 468                 if (alarm->node.expires > now)
 469                         return overrun;
 470                 /*
 471                  * This (and the ktime_add() below) is the
 472                  * correction for exact:
 473                  */
 474                 overrun++;
 475         }
 476
 477         alarm->node.expires = ktime_add_safe(alarm->node.expires, interval);
 478         return overrun;
 479 }
 480 EXPORT_SYMBOL_GPL(alarm_forward);
 481
 482 static u64 __alarm_forward_now(struct alarm *alarm, ktime_t interval, bool throttle)
 483 {
 484         struct alarm_base *base = &alarm_bases[alarm->type];
 485         ktime_t now = base->gettime();
 486
 487         if (IS_ENABLED(CONFIG_HIGH_RES_TIMERS) && throttle) {
 488                 /*
 489                  * Same issue as with posix_timer_fn(). Timers which are
 490                  * periodic but the signal is ignored can starve the system
 491                  * with a very small interval. The real fix which was
 492                  * promised in the context of posix_timer_fn() never
 493                  * materialized, but someone should really work on it.
 494                  *
 495                  * To prevent DOS fake @now to be 1 jiffie out which keeps
 496                  * the overrun accounting correct but creates an
 497                  * inconsistency vs. timer_gettime(2).
 498                  */
 499                 ktime_t kj = NSEC_PER_SEC / HZ;
 500
 501                 if (interval < kj)
 502                         now = ktime_add(now, kj);
 503         }
 504
 505         return alarm_forward(alarm, now, interval);
 506 }
 507
 508 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 509 {
 510         return __alarm_forward_now(alarm, interval, false);
 511 }
 512 EXPORT_SYMBOL_GPL(alarm_forward_now);
 513
 514 #ifdef CONFIG_POSIX_TIMERS
 515
 516 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 517 {
 518         struct alarm_base *base;
 519         unsigned long flags;
 520         ktime_t delta;
 521
 522         switch(type) {
 523         case ALARM_REALTIME:
 524                 base = &alarm_bases[ALARM_REALTIME];
 525                 type = ALARM_REALTIME_FREEZER;
 526                 break;
 527         case ALARM_BOOTTIME:
 528                 base = &alarm_bases[ALARM_BOOTTIME];
 529                 type = ALARM_BOOTTIME_FREEZER;
 530                 break;
 531         default:
 532                 WARN_ONCE(1, "Invalid alarm type: %d\n", type);
 533                 return;
 534         }
 535
 536         delta = ktime_sub(absexp, base->gettime());
 537
 538         spin_lock_irqsave(&freezer_delta_lock, flags);
 539         if (!freezer_delta || (delta < freezer_delta)) {
 540                 freezer_delta = delta;
 541                 freezer_expires = absexp;
 542                 freezer_alarmtype = type;
 543         }
 544         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 545 }
 546
 547 /**
 548  * clock2alarm - helper that converts from clockid to alarmtypes
 549  * @clockid: clockid.
 550  */
 551 static enum alarmtimer_type clock2alarm(clockid_t clockid)
 552 {
 553         if (clockid == CLOCK_REALTIME_ALARM)
 554                 return ALARM_REALTIME;
 555         if (clockid == CLOCK_BOOTTIME_ALARM)
 556                 return ALARM_BOOTTIME;
 557         return -1;
 558 }
 559
 560 /**
 561  * alarm_handle_timer - Callback for posix timers
 562  * @alarm: alarm that fired
 563  *
 564  * Posix timer callback for expired alarm timers.
 565  */
 566 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 567                                                         ktime_t now)
 568 {
 569         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 570                                             it.alarm.alarmtimer);
 571         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
 572         unsigned long flags;
 573         int si_private = 0;
 574
 575         spin_lock_irqsave(&ptr->it_lock, flags);
 576
 577         ptr->it_active = 0;
 578         if (ptr->it_interval)
 579                 si_private = ++ptr->it_requeue_pending;
 580
 581         if (posix_timer_event(ptr, si_private) && ptr->it_interval) {
 582                 /*
 583                  * Handle ignored signals and rearm the timer. This will go
 584                  * away once we handle ignored signals proper. Ensure that
 585                  * small intervals cannot starve the system.
 586                  */
 587                 ptr->it_overrun += __alarm_forward_now(alarm, ptr->it_interval, true);
 588                 ++ptr->it_requeue_pending;
 589                 ptr->it_active = 1;
 590                 result = ALARMTIMER_RESTART;
 591         }
 592         spin_unlock_irqrestore(&ptr->it_lock, flags);
 593
 594         return result;
 595 }
 596
 597 /**
 598  * alarm_timer_rearm - Posix timer callback for rearming timer
 599  * @timr:       Pointer to the posixtimer data struct
 600  */
 601 static void alarm_timer_rearm(struct k_itimer *timr)
 602 {
 603         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 604
 605         timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
 606         alarm_start(alarm, alarm->node.expires);
 607 }
 608
 609 /**
 610  * alarm_timer_forward - Posix timer callback for forwarding timer
 611  * @timr:       Pointer to the posixtimer data struct
 612  * @now:        Current time to forward the timer against
 613  */
 614 static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
 615 {
 616         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 617
 618         return alarm_forward(alarm, timr->it_interval, now);
 619 }
 620
 621 /**
 622  * alarm_timer_remaining - Posix timer callback to retrieve remaining time
 623  * @timr:       Pointer to the posixtimer data struct
 624  * @now:        Current time to calculate against
 625  */
 626 static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
 627 {
 628         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 629
 630         return ktime_sub(alarm->node.expires, now);
 631 }
 632
 633 /**
 634  * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
 635  * @timr:       Pointer to the posixtimer data struct
 636  */
 637 static int alarm_timer_try_to_cancel(struct k_itimer *timr)
 638 {
 639         return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
 640 }
 641
 642 /**
 643  * alarm_timer_wait_running - Posix timer callback to wait for a timer
 644  * @timr:       Pointer to the posixtimer data struct
 645  *
 646  * Called from the core code when timer cancel detected that the callback
 647  * is running. @timr is unlocked and rcu read lock is held to prevent it
 648  * from being freed.
 649  */
 650 static void alarm_timer_wait_running(struct k_itimer *timr)
 651 {
 652         hrtimer_cancel_wait_running(&timr->it.alarm.alarmtimer.timer);
 653 }
 654
 655 /**
 656  * alarm_timer_arm - Posix timer callback to arm a timer
 657  * @timr:       Pointer to the posixtimer data struct
 658  * @expires:    The new expiry time
 659  * @absolute:   Expiry value is absolute time
 660  * @sigev_none: Posix timer does not deliver signals
 661  */
 662 static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
 663                             bool absolute, bool sigev_none)
 664 {
 665         struct alarm *alarm = &timr->it.alarm.alarmtimer;
 666         struct alarm_base *base = &alarm_bases[alarm->type];
 667
 668         if (!absolute)
 669                 expires = ktime_add_safe(expires, base->gettime());
 670         if (sigev_none)
 671                 alarm->node.expires = expires;
 672         else
 673                 alarm_start(&timr->it.alarm.alarmtimer, expires);
 674 }
 675
 676 /**
 677  * alarm_clock_getres - posix getres interface
 678  * @which_clock: clockid
 679  * @tp: timespec to fill
 680  *
 681  * Returns the granularity of underlying alarm base clock
 682  */
 683 static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 684 {
 685         if (!alarmtimer_get_rtcdev())
 686                 return -EINVAL;
 687
 688         tp->tv_sec = 0;
 689         tp->tv_nsec = hrtimer_resolution;
 690         return 0;
 691 }
 692
 693 /**
 694  * alarm_clock_get - posix clock_get interface
 695  * @which_clock: clockid
 696  * @tp: timespec to fill.
 697  *
 698  * Provides the underlying alarm base time.
 699  */
 700 static int alarm_clock_get(clockid_t which_clock, struct timespec64 *tp)
 701 {
 702         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 703
 704         if (!alarmtimer_get_rtcdev())
 705                 return -EINVAL;
 706
 707         *tp = ktime_to_timespec64(base->gettime());
 708         return 0;
 709 }
 710
 711 /**
 712  * alarm_timer_create - posix timer_create interface
 713  * @new_timer: k_itimer pointer to manage
 714  *
 715  * Initializes the k_itimer structure.
 716  */
 717 static int alarm_timer_create(struct k_itimer *new_timer)
 718 {
 719         enum  alarmtimer_type type;
 720
 721         if (!alarmtimer_get_rtcdev())
 722                 return -EOPNOTSUPP;
 723
 724         if (!capable(CAP_WAKE_ALARM))
 725                 return -EPERM;
 726
 727         type = clock2alarm(new_timer->it_clock);
 728         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 729         return 0;
 730 }
 731
 732 /**
 733  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 734  * @alarm: ptr to alarm that fired
 735  *
 736  * Wakes up the task that set the alarmtimer
 737  */
 738 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 739                                                                 ktime_t now)
 740 {
 741         struct task_struct *task = (struct task_struct *)alarm->data;
 742
 743         alarm->data = NULL;
 744         if (task)
 745                 wake_up_process(task);
 746         return ALARMTIMER_NORESTART;
 747 }
 748
 749 /**
 750  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 751  * @alarm: ptr to alarmtimer
 752  * @absexp: absolute expiration time
 753  *
 754  * Sets the alarm timer and sleeps until it is fired or interrupted.
 755  */
 756 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
 757                                 enum alarmtimer_type type)
 758 {
 759         struct restart_block *restart;
 760         alarm->data = (void *)current;
 761         do {
 762                 set_current_state(TASK_INTERRUPTIBLE);
 763                 alarm_start(alarm, absexp);
 764                 if (likely(alarm->data))
 765                         schedule();
 766
 767                 alarm_cancel(alarm);
 768         } while (alarm->data && !signal_pending(current));
 769
 770         __set_current_state(TASK_RUNNING);
 771
 772         destroy_hrtimer_on_stack(&alarm->timer);
 773
 774         if (!alarm->data)
 775                 return 0;
 776
 777         if (freezing(current))
 778                 alarmtimer_freezerset(absexp, type);
 779         restart = &current->restart_block;
 780         if (restart->nanosleep.type != TT_NONE) {
 781                 struct timespec64 rmt;
 782                 ktime_t rem;
 783
 784                 rem = ktime_sub(absexp, alarm_bases[type].gettime());
 785
 786                 if (rem <= 0)
 787                         return 0;
 788                 rmt = ktime_to_timespec64(rem);
 789
 790                 return nanosleep_copyout(restart, &rmt);
 791         }
 792         return -ERESTART_RESTARTBLOCK;
 793 }
 794
 795 static void
 796 alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
 797                     enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 798 {
 799         hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid,
 800                               HRTIMER_MODE_ABS);
 801         __alarm_init(alarm, type, function);
 802 }
 803
 804 /**
 805  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 806  * @restart: ptr to restart block
 807  *
 808  * Handles restarted clock_nanosleep calls
 809  */
 810 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 811 {
 812         enum  alarmtimer_type type = restart->nanosleep.clockid;
 813         ktime_t exp = restart->nanosleep.expires;
 814         struct alarm alarm;
 815
 816         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 817
 818         return alarmtimer_do_nsleep(&alarm, exp, type);
 819 }
 820
 821 /**
 822  * alarm_timer_nsleep - alarmtimer nanosleep
 823  * @which_clock: clockid
 824  * @flags: determins abstime or relative
 825  * @tsreq: requested sleep time (abs or rel)
 826  * @rmtp: remaining sleep time saved
 827  *
 828  * Handles clock_nanosleep calls against _ALARM clockids
 829  */
 830 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 831                               const struct timespec64 *tsreq)
 832 {
 833         enum  alarmtimer_type type = clock2alarm(which_clock);
 834         struct restart_block *restart = &current->restart_block;
 835         struct alarm alarm;
 836         ktime_t exp;
 837         int ret = 0;
 838
 839         if (!alarmtimer_get_rtcdev())
 840                 return -EOPNOTSUPP;
 841
 842         if (flags & ~TIMER_ABSTIME)
 843                 return -EINVAL;
 844
 845         if (!capable(CAP_WAKE_ALARM))
 846                 return -EPERM;
 847
 848         alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 849
 850         exp = timespec64_to_ktime(*tsreq);
 851         /* Convert (if necessary) to absolute time */
 852         if (flags != TIMER_ABSTIME) {
 853                 ktime_t now = alarm_bases[type].gettime();
 854
 855                 exp = ktime_add_safe(now, exp);
 856         }
 857
 858         ret = alarmtimer_do_nsleep(&alarm, exp, type);
 859         if (ret != -ERESTART_RESTARTBLOCK)
 860                 return ret;
 861
 862         /* abs timers don't set remaining time or restart */
 863         if (flags == TIMER_ABSTIME)
 864                 return -ERESTARTNOHAND;
 865
 866         restart->nanosleep.clockid = type;
 867         restart->nanosleep.expires = exp;
 868         set_restart_fn(restart, alarm_timer_nsleep_restart);
 869         return ret;
 870 }
 871
 872 const struct k_clock alarm_clock = {
 873         .clock_getres           = alarm_clock_getres,
 874         .clock_get              = alarm_clock_get,
 875         .timer_create           = alarm_timer_create,
 876         .timer_set              = common_timer_set,
 877         .timer_del              = common_timer_del,
 878         .timer_get              = common_timer_get,
 879         .timer_arm              = alarm_timer_arm,
 880         .timer_rearm            = alarm_timer_rearm,
 881         .timer_forward          = alarm_timer_forward,
 882         .timer_remaining        = alarm_timer_remaining,
 883         .timer_try_to_cancel    = alarm_timer_try_to_cancel,
 884         .timer_wait_running     = alarm_timer_wait_running,
 885         .nsleep                 = alarm_timer_nsleep,
 886 };
 887 #endif /* CONFIG_POSIX_TIMERS */
 888
 889
 890 /* Suspend hook structures */
 891 static const struct dev_pm_ops alarmtimer_pm_ops = {
 892         .suspend = alarmtimer_suspend,
 893         .resume = alarmtimer_resume,
 894 };
 895
 896 static struct platform_driver alarmtimer_driver = {
 897         .driver = {
 898                 .name = "alarmtimer",
 899                 .pm = &alarmtimer_pm_ops,
 900         }
 901 };
 902
 903 /**
 904  * alarmtimer_init - Initialize alarm timer code
 905  *
 906  * This function initializes the alarm bases and registers
 907  * the posix clock ids.
 908  */
 909 static int __init alarmtimer_init(void)
 910 {
 911         int error;
 912         int i;
 913
 914         alarmtimer_rtc_timer_init();
 915
 916         /* Initialize alarm bases */
 917         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 918         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
 919         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 920         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
 921         for (i = 0; i < ALARM_NUMTYPE; i++) {
 922                 timerqueue_init_head(&alarm_bases[i].timerqueue);
 923                 spin_lock_init(&alarm_bases[i].lock);
 924         }
 925
 926         error = alarmtimer_rtc_interface_setup();
 927         if (error)
 928                 return error;
 929
 930         error = platform_driver_register(&alarmtimer_driver);
 931         if (error)
 932                 goto out_if;
 933
 934         return 0;
 935 out_if:
 936         alarmtimer_rtc_interface_remove();
 937         return error;
 938 }
 939 device_initcall(alarmtimer_init);