kernel/time/alarmtimer.c

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

DEFINITIONS
