kernel/time/alarmtimer.c

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