linux/kernel/time/alarmtimer.c
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   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#include <linux/time_namespace.h>
  30
  31#include "posix-timers.h"
  32
  33#define CREATE_TRACE_POINTS
  34#include <trace/events/alarmtimer.h>
  35
  36/**
  37 * struct alarm_base - Alarm timer bases
  38 * @lock:               Lock for syncrhonized access to the base
  39 * @timerqueue:         Timerqueue head managing the list of events
  40 * @get_ktime:          Function to read the time correlating to the base
  41 * @get_timespec:       Function to read the namespace time correlating to the base
  42 * @base_clockid:       clockid for the base
  43 */
  44static struct alarm_base {
  45        spinlock_t              lock;
  46        struct timerqueue_head  timerqueue;
  47        ktime_t                 (*get_ktime)(void);
  48        void                    (*get_timespec)(struct timespec64 *tp);
  49        clockid_t               base_clockid;
  50} alarm_bases[ALARM_NUMTYPE];
  51
  52#if defined(CONFIG_POSIX_TIMERS) || defined(CONFIG_RTC_CLASS)
  53/* freezer information to handle clock_nanosleep triggered wakeups */
  54static enum alarmtimer_type freezer_alarmtype;
  55static ktime_t freezer_expires;
  56static ktime_t freezer_delta;
  57static DEFINE_SPINLOCK(freezer_delta_lock);
  58#endif
  59
  60#ifdef CONFIG_RTC_CLASS
  61/* rtc timer and device for setting alarm wakeups at suspend */
  62static struct rtc_timer         rtctimer;
  63static struct rtc_device        *rtcdev;
  64static DEFINE_SPINLOCK(rtcdev_lock);
  65
  66/**
  67 * alarmtimer_get_rtcdev - Return selected rtcdevice
  68 *
  69 * This function returns the rtc device to use for wakealarms.
  70 */
  71struct rtc_device *alarmtimer_get_rtcdev(void)
  72{
  73        unsigned long flags;
  74        struct rtc_device *ret;
  75
  76        spin_lock_irqsave(&rtcdev_lock, flags);
  77        ret = rtcdev;
  78        spin_unlock_irqrestore(&rtcdev_lock, flags);
  79
  80        return ret;
  81}
  82EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
  83
  84static int alarmtimer_rtc_add_device(struct device *dev,
  85                                struct class_interface *class_intf)
  86{
  87        unsigned long flags;
  88        struct rtc_device *rtc = to_rtc_device(dev);
  89        struct platform_device *pdev;
  90        int ret = 0;
  91
  92        if (rtcdev)
  93                return -EBUSY;
  94
  95        if (!rtc->ops->set_alarm)
  96                return -1;
  97        if (!device_may_wakeup(rtc->dev.parent))
  98                return -1;
  99
 100        pdev = platform_device_register_data(dev, "alarmtimer",
 101                                             PLATFORM_DEVID_AUTO, NULL, 0);
 102        if (!IS_ERR(pdev))
 103                device_init_wakeup(&pdev->dev, true);
 104
 105        spin_lock_irqsave(&rtcdev_lock, flags);
 106        if (!IS_ERR(pdev) && !rtcdev) {
 107                if (!try_module_get(rtc->owner)) {
 108                        ret = -1;
 109                        goto unlock;
 110                }
 111
 112                rtcdev = rtc;
 113                /* hold a reference so it doesn't go away */
 114                get_device(dev);
 115                pdev = NULL;
 116        } else {
 117                ret = -1;
 118        }
 119unlock:
 120        spin_unlock_irqrestore(&rtcdev_lock, flags);
 121
 122        platform_device_unregister(pdev);
 123
 124        return ret;
 125}
 126
 127static inline void alarmtimer_rtc_timer_init(void)
 128{
 129        rtc_timer_init(&rtctimer, NULL, NULL);
 130}
 131
 132static struct class_interface alarmtimer_rtc_interface = {
 133        .add_dev = &alarmtimer_rtc_add_device,
 134};
 135
 136static int alarmtimer_rtc_interface_setup(void)
 137{
 138        alarmtimer_rtc_interface.class = rtc_class;
 139        return class_interface_register(&alarmtimer_rtc_interface);
 140}
 141static void alarmtimer_rtc_interface_remove(void)
 142{
 143        class_interface_unregister(&alarmtimer_rtc_interface);
 144}
 145#else
 146static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
 147static inline void alarmtimer_rtc_interface_remove(void) { }
 148static inline void alarmtimer_rtc_timer_init(void) { }
 149#endif
 150
 151/**
 152 * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
 153 * @base: pointer to the base where the timer is being run
 154 * @alarm: pointer to alarm being enqueued.
 155 *
 156 * Adds alarm to a alarm_base timerqueue
 157 *
 158 * Must hold base->lock when calling.
 159 */
 160static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
 161{
 162        if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
 163                timerqueue_del(&base->timerqueue, &alarm->node);
 164
 165        timerqueue_add(&base->timerqueue, &alarm->node);
 166        alarm->state |= ALARMTIMER_STATE_ENQUEUED;
 167}
 168
 169/**
 170 * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
 171 * @base: pointer to the base where the timer is running
 172 * @alarm: pointer to alarm being removed
 173 *
 174 * Removes alarm to a alarm_base timerqueue
 175 *
 176 * Must hold base->lock when calling.
 177 */
 178static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
 179{
 180        if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
 181                return;
 182
 183        timerqueue_del(&base->timerqueue, &alarm->node);
 184        alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
 185}
 186
 187
 188/**
 189 * alarmtimer_fired - Handles alarm hrtimer being fired.
 190 * @timer: pointer to hrtimer being run
 191 *
 192 * When a alarm timer fires, this runs through the timerqueue to
 193 * see which alarms expired, and runs those. If there are more alarm
 194 * timers queued for the future, we set the hrtimer to fire when
 195 * when the next future alarm timer expires.
 196 */
 197static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 198{
 199        struct alarm *alarm = container_of(timer, struct alarm, timer);
 200        struct alarm_base *base = &alarm_bases[alarm->type];
 201        unsigned long flags;
 202        int ret = HRTIMER_NORESTART;
 203        int restart = ALARMTIMER_NORESTART;
 204
 205        spin_lock_irqsave(&base->lock, flags);
 206        alarmtimer_dequeue(base, alarm);
 207        spin_unlock_irqrestore(&base->lock, flags);
 208
 209        if (alarm->function)
 210                restart = alarm->function(alarm, base->get_ktime());
 211
 212        spin_lock_irqsave(&base->lock, flags);
 213        if (restart != ALARMTIMER_NORESTART) {
 214                hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 215                alarmtimer_enqueue(base, alarm);
 216                ret = HRTIMER_RESTART;
 217        }
 218        spin_unlock_irqrestore(&base->lock, flags);
 219
 220        trace_alarmtimer_fired(alarm, base->get_ktime());
 221        return ret;
 222
 223}
 224
 225ktime_t alarm_expires_remaining(const struct alarm *alarm)
 226{
 227        struct alarm_base *base = &alarm_bases[alarm->type];
 228        return ktime_sub(alarm->node.expires, base->get_ktime());
 229}
 230EXPORT_SYMBOL_GPL(alarm_expires_remaining);
 231
 232#ifdef CONFIG_RTC_CLASS
 233/**
 234 * alarmtimer_suspend - Suspend time callback
 235 * @dev: unused
 236 *
 237 * When we are going into suspend, we look through the bases
 238 * to see which is the soonest timer to expire. We then
 239 * set an rtc timer to fire that far into the future, which
 240 * will wake us from suspend.
 241 */
 242static int alarmtimer_suspend(struct device *dev)
 243{
 244        ktime_t min, now, expires;
 245        int i, ret, type;
 246        struct rtc_device *rtc;
 247        unsigned long flags;
 248        struct rtc_time tm;
 249
 250        spin_lock_irqsave(&freezer_delta_lock, flags);
 251        min = freezer_delta;
 252        expires = freezer_expires;
 253        type = freezer_alarmtype;
 254        freezer_delta = 0;
 255        spin_unlock_irqrestore(&freezer_delta_lock, flags);
 256
 257        rtc = alarmtimer_get_rtcdev();
 258        /* If we have no rtcdev, just return */
 259        if (!rtc)
 260                return 0;
 261
 262        /* Find the soonest timer to expire*/
 263        for (i = 0; i < ALARM_NUMTYPE; i++) {
 264                struct alarm_base *base = &alarm_bases[i];
 265                struct timerqueue_node *next;
 266                ktime_t delta;
 267
 268                spin_lock_irqsave(&base->lock, flags);
 269                next = timerqueue_getnext(&base->timerqueue);
 270                spin_unlock_irqrestore(&base->lock, flags);
 271                if (!next)
 272                        continue;
 273                delta = ktime_sub(next->expires, base->get_ktime());
 274                if (!min || (delta < min)) {
 275                        expires = next->expires;
 276                        min = delta;
 277                        type = i;
 278                }
 279        }
 280        if (min == 0)
 281                return 0;
 282
 283        if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
 284                pm_wakeup_event(dev, 2 * MSEC_PER_SEC);
 285                return -EBUSY;
 286        }
 287
 288        trace_alarmtimer_suspend(expires, type);
 289
 290        /* Setup an rtc timer to fire that far in the future */
 291        rtc_timer_cancel(rtc, &rtctimer);
 292        rtc_read_time(rtc, &tm);
 293        now = rtc_tm_to_ktime(tm);
 294        now = ktime_add(now, min);
 295
 296        /* Set alarm, if in the past reject suspend briefly to handle */
 297        ret = rtc_timer_start(rtc, &rtctimer, now, 0);
 298        if (ret < 0)
 299                pm_wakeup_event(dev, MSEC_PER_SEC);
 300        return ret;
 301}
 302
 303static int alarmtimer_resume(struct device *dev)
 304{
 305        struct rtc_device *rtc;
 306
 307        rtc = alarmtimer_get_rtcdev();
 308        if (rtc)
 309                rtc_timer_cancel(rtc, &rtctimer);
 310        return 0;
 311}
 312
 313#else
 314static int alarmtimer_suspend(struct device *dev)
 315{
 316        return 0;
 317}
 318
 319static int alarmtimer_resume(struct device *dev)
 320{
 321        return 0;
 322}
 323#endif
 324
 325static void
 326__alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 327             enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 328{
 329        timerqueue_init(&alarm->node);
 330        alarm->timer.function = alarmtimer_fired;
 331        alarm->function = function;
 332        alarm->type = type;
 333        alarm->state = ALARMTIMER_STATE_INACTIVE;
 334}
 335
 336/**
 337 * alarm_init - Initialize an alarm structure
 338 * @alarm: ptr to alarm to be initialized
 339 * @type: the type of the alarm
 340 * @function: callback that is run when the alarm fires
 341 */
 342void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
 343                enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 344{
 345        hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
 346                     HRTIMER_MODE_ABS);
 347        __alarm_init(alarm, type, function);
 348}
 349EXPORT_SYMBOL_GPL(alarm_init);
 350
 351/**
 352 * alarm_start - Sets an absolute alarm to fire
 353 * @alarm: ptr to alarm to set
 354 * @start: time to run the alarm
 355 */
 356void alarm_start(struct alarm *alarm, ktime_t start)
 357{
 358        struct alarm_base *base = &alarm_bases[alarm->type];
 359        unsigned long flags;
 360
 361        spin_lock_irqsave(&base->lock, flags);
 362        alarm->node.expires = start;
 363        alarmtimer_enqueue(base, alarm);
 364        hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
 365        spin_unlock_irqrestore(&base->lock, flags);
 366
 367        trace_alarmtimer_start(alarm, base->get_ktime());
 368}
 369EXPORT_SYMBOL_GPL(alarm_start);
 370
 371/**
 372 * alarm_start_relative - Sets a relative alarm to fire
 373 * @alarm: ptr to alarm to set
 374 * @start: time relative to now to run the alarm
 375 */
 376void alarm_start_relative(struct alarm *alarm, ktime_t start)
 377{
 378        struct alarm_base *base = &alarm_bases[alarm->type];
 379
 380        start = ktime_add_safe(start, base->get_ktime());
 381        alarm_start(alarm, start);
 382}
 383EXPORT_SYMBOL_GPL(alarm_start_relative);
 384
 385void alarm_restart(struct alarm *alarm)
 386{
 387        struct alarm_base *base = &alarm_bases[alarm->type];
 388        unsigned long flags;
 389
 390        spin_lock_irqsave(&base->lock, flags);
 391        hrtimer_set_expires(&alarm->timer, alarm->node.expires);
 392        hrtimer_restart(&alarm->timer);
 393        alarmtimer_enqueue(base, alarm);
 394        spin_unlock_irqrestore(&base->lock, flags);
 395}
 396EXPORT_SYMBOL_GPL(alarm_restart);
 397
 398/**
 399 * alarm_try_to_cancel - Tries to cancel an alarm timer
 400 * @alarm: ptr to alarm to be canceled
 401 *
 402 * Returns 1 if the timer was canceled, 0 if it was not running,
 403 * and -1 if the callback was running
 404 */
 405int alarm_try_to_cancel(struct alarm *alarm)
 406{
 407        struct alarm_base *base = &alarm_bases[alarm->type];
 408        unsigned long flags;
 409        int ret;
 410
 411        spin_lock_irqsave(&base->lock, flags);
 412        ret = hrtimer_try_to_cancel(&alarm->timer);
 413        if (ret >= 0)
 414                alarmtimer_dequeue(base, alarm);
 415        spin_unlock_irqrestore(&base->lock, flags);
 416
 417        trace_alarmtimer_cancel(alarm, base->get_ktime());
 418        return ret;
 419}
 420EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
 421
 422
 423/**
 424 * alarm_cancel - Spins trying to cancel an alarm timer until it is done
 425 * @alarm: ptr to alarm to be canceled
 426 *
 427 * Returns 1 if the timer was canceled, 0 if it was not active.
 428 */
 429int alarm_cancel(struct alarm *alarm)
 430{
 431        for (;;) {
 432                int ret = alarm_try_to_cancel(alarm);
 433                if (ret >= 0)
 434                        return ret;
 435                hrtimer_cancel_wait_running(&alarm->timer);
 436        }
 437}
 438EXPORT_SYMBOL_GPL(alarm_cancel);
 439
 440
 441u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
 442{
 443        u64 overrun = 1;
 444        ktime_t delta;
 445
 446        delta = ktime_sub(now, alarm->node.expires);
 447
 448        if (delta < 0)
 449                return 0;
 450
 451        if (unlikely(delta >= interval)) {
 452                s64 incr = ktime_to_ns(interval);
 453
 454                overrun = ktime_divns(delta, incr);
 455
 456                alarm->node.expires = ktime_add_ns(alarm->node.expires,
 457                                                        incr*overrun);
 458
 459                if (alarm->node.expires > now)
 460                        return overrun;
 461                /*
 462                 * This (and the ktime_add() below) is the
 463                 * correction for exact:
 464                 */
 465                overrun++;
 466        }
 467
 468        alarm->node.expires = ktime_add_safe(alarm->node.expires, interval);
 469        return overrun;
 470}
 471EXPORT_SYMBOL_GPL(alarm_forward);
 472
 473u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 474{
 475        struct alarm_base *base = &alarm_bases[alarm->type];
 476
 477        return alarm_forward(alarm, base->get_ktime(), interval);
 478}
 479EXPORT_SYMBOL_GPL(alarm_forward_now);
 480
 481#ifdef CONFIG_POSIX_TIMERS
 482
 483static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 484{
 485        struct alarm_base *base;
 486        unsigned long flags;
 487        ktime_t delta;
 488
 489        switch(type) {
 490        case ALARM_REALTIME:
 491                base = &alarm_bases[ALARM_REALTIME];
 492                type = ALARM_REALTIME_FREEZER;
 493                break;
 494        case ALARM_BOOTTIME:
 495                base = &alarm_bases[ALARM_BOOTTIME];
 496                type = ALARM_BOOTTIME_FREEZER;
 497                break;
 498        default:
 499                WARN_ONCE(1, "Invalid alarm type: %d\n", type);
 500                return;
 501        }
 502
 503        delta = ktime_sub(absexp, base->get_ktime());
 504
 505        spin_lock_irqsave(&freezer_delta_lock, flags);
 506        if (!freezer_delta || (delta < freezer_delta)) {
 507                freezer_delta = delta;
 508                freezer_expires = absexp;
 509                freezer_alarmtype = type;
 510        }
 511        spin_unlock_irqrestore(&freezer_delta_lock, flags);
 512}
 513
 514/**
 515 * clock2alarm - helper that converts from clockid to alarmtypes
 516 * @clockid: clockid.
 517 */
 518static enum alarmtimer_type clock2alarm(clockid_t clockid)
 519{
 520        if (clockid == CLOCK_REALTIME_ALARM)
 521                return ALARM_REALTIME;
 522        if (clockid == CLOCK_BOOTTIME_ALARM)
 523                return ALARM_BOOTTIME;
 524        return -1;
 525}
 526
 527/**
 528 * alarm_handle_timer - Callback for posix timers
 529 * @alarm: alarm that fired
 530 *
 531 * Posix timer callback for expired alarm timers.
 532 */
 533static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 534                                                        ktime_t now)
 535{
 536        struct k_itimer *ptr = container_of(alarm, struct k_itimer,
 537                                            it.alarm.alarmtimer);
 538        enum alarmtimer_restart result = ALARMTIMER_NORESTART;
 539        unsigned long flags;
 540        int si_private = 0;
 541
 542        spin_lock_irqsave(&ptr->it_lock, flags);
 543
 544        ptr->it_active = 0;
 545        if (ptr->it_interval)
 546                si_private = ++ptr->it_requeue_pending;
 547
 548        if (posix_timer_event(ptr, si_private) && ptr->it_interval) {
 549                /*
 550                 * Handle ignored signals and rearm the timer. This will go
 551                 * away once we handle ignored signals proper.
 552                 */
 553                ptr->it_overrun += alarm_forward_now(alarm, ptr->it_interval);
 554                ++ptr->it_requeue_pending;
 555                ptr->it_active = 1;
 556                result = ALARMTIMER_RESTART;
 557        }
 558        spin_unlock_irqrestore(&ptr->it_lock, flags);
 559
 560        return result;
 561}
 562
 563/**
 564 * alarm_timer_rearm - Posix timer callback for rearming timer
 565 * @timr:       Pointer to the posixtimer data struct
 566 */
 567static void alarm_timer_rearm(struct k_itimer *timr)
 568{
 569        struct alarm *alarm = &timr->it.alarm.alarmtimer;
 570
 571        timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
 572        alarm_start(alarm, alarm->node.expires);
 573}
 574
 575/**
 576 * alarm_timer_forward - Posix timer callback for forwarding timer
 577 * @timr:       Pointer to the posixtimer data struct
 578 * @now:        Current time to forward the timer against
 579 */
 580static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
 581{
 582        struct alarm *alarm = &timr->it.alarm.alarmtimer;
 583
 584        return alarm_forward(alarm, timr->it_interval, now);
 585}
 586
 587/**
 588 * alarm_timer_remaining - Posix timer callback to retrieve remaining time
 589 * @timr:       Pointer to the posixtimer data struct
 590 * @now:        Current time to calculate against
 591 */
 592static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
 593{
 594        struct alarm *alarm = &timr->it.alarm.alarmtimer;
 595
 596        return ktime_sub(alarm->node.expires, now);
 597}
 598
 599/**
 600 * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
 601 * @timr:       Pointer to the posixtimer data struct
 602 */
 603static int alarm_timer_try_to_cancel(struct k_itimer *timr)
 604{
 605        return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
 606}
 607
 608/**
 609 * alarm_timer_wait_running - Posix timer callback to wait for a timer
 610 * @timr:       Pointer to the posixtimer data struct
 611 *
 612 * Called from the core code when timer cancel detected that the callback
 613 * is running. @timr is unlocked and rcu read lock is held to prevent it
 614 * from being freed.
 615 */
 616static void alarm_timer_wait_running(struct k_itimer *timr)
 617{
 618        hrtimer_cancel_wait_running(&timr->it.alarm.alarmtimer.timer);
 619}
 620
 621/**
 622 * alarm_timer_arm - Posix timer callback to arm a timer
 623 * @timr:       Pointer to the posixtimer data struct
 624 * @expires:    The new expiry time
 625 * @absolute:   Expiry value is absolute time
 626 * @sigev_none: Posix timer does not deliver signals
 627 */
 628static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
 629                            bool absolute, bool sigev_none)
 630{
 631        struct alarm *alarm = &timr->it.alarm.alarmtimer;
 632        struct alarm_base *base = &alarm_bases[alarm->type];
 633
 634        if (!absolute)
 635                expires = ktime_add_safe(expires, base->get_ktime());
 636        if (sigev_none)
 637                alarm->node.expires = expires;
 638        else
 639                alarm_start(&timr->it.alarm.alarmtimer, expires);
 640}
 641
 642/**
 643 * alarm_clock_getres - posix getres interface
 644 * @which_clock: clockid
 645 * @tp: timespec to fill
 646 *
 647 * Returns the granularity of underlying alarm base clock
 648 */
 649static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 650{
 651        if (!alarmtimer_get_rtcdev())
 652                return -EINVAL;
 653
 654        tp->tv_sec = 0;
 655        tp->tv_nsec = hrtimer_resolution;
 656        return 0;
 657}
 658
 659/**
 660 * alarm_clock_get_timespec - posix clock_get_timespec interface
 661 * @which_clock: clockid
 662 * @tp: timespec to fill.
 663 *
 664 * Provides the underlying alarm base time in a tasks time namespace.
 665 */
 666static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 667{
 668        struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 669
 670        if (!alarmtimer_get_rtcdev())
 671                return -EINVAL;
 672
 673        base->get_timespec(tp);
 674
 675        return 0;
 676}
 677
 678/**
 679 * alarm_clock_get_ktime - posix clock_get_ktime interface
 680 * @which_clock: clockid
 681 *
 682 * Provides the underlying alarm base time in the root namespace.
 683 */
 684static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
 685{
 686        struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 687
 688        if (!alarmtimer_get_rtcdev())
 689                return -EINVAL;
 690
 691        return base->get_ktime();
 692}
 693
 694/**
 695 * alarm_timer_create - posix timer_create interface
 696 * @new_timer: k_itimer pointer to manage
 697 *
 698 * Initializes the k_itimer structure.
 699 */
 700static int alarm_timer_create(struct k_itimer *new_timer)
 701{
 702        enum  alarmtimer_type type;
 703
 704        if (!alarmtimer_get_rtcdev())
 705                return -EOPNOTSUPP;
 706
 707        if (!capable(CAP_WAKE_ALARM))
 708                return -EPERM;
 709
 710        type = clock2alarm(new_timer->it_clock);
 711        alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
 712        return 0;
 713}
 714
 715/**
 716 * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
 717 * @alarm: ptr to alarm that fired
 718 *
 719 * Wakes up the task that set the alarmtimer
 720 */
 721static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
 722                                                                ktime_t now)
 723{
 724        struct task_struct *task = (struct task_struct *)alarm->data;
 725
 726        alarm->data = NULL;
 727        if (task)
 728                wake_up_process(task);
 729        return ALARMTIMER_NORESTART;
 730}
 731
 732/**
 733 * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
 734 * @alarm: ptr to alarmtimer
 735 * @absexp: absolute expiration time
 736 *
 737 * Sets the alarm timer and sleeps until it is fired or interrupted.
 738 */
 739static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
 740                                enum alarmtimer_type type)
 741{
 742        struct restart_block *restart;
 743        alarm->data = (void *)current;
 744        do {
 745                set_current_state(TASK_INTERRUPTIBLE);
 746                alarm_start(alarm, absexp);
 747                if (likely(alarm->data))
 748                        schedule();
 749
 750                alarm_cancel(alarm);
 751        } while (alarm->data && !signal_pending(current));
 752
 753        __set_current_state(TASK_RUNNING);
 754
 755        destroy_hrtimer_on_stack(&alarm->timer);
 756
 757        if (!alarm->data)
 758                return 0;
 759
 760        if (freezing(current))
 761                alarmtimer_freezerset(absexp, type);
 762        restart = &current->restart_block;
 763        if (restart->nanosleep.type != TT_NONE) {
 764                struct timespec64 rmt;
 765                ktime_t rem;
 766
 767                rem = ktime_sub(absexp, alarm_bases[type].get_ktime());
 768
 769                if (rem <= 0)
 770                        return 0;
 771                rmt = ktime_to_timespec64(rem);
 772
 773                return nanosleep_copyout(restart, &rmt);
 774        }
 775        return -ERESTART_RESTARTBLOCK;
 776}
 777
 778static void
 779alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
 780                    enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 781{
 782        hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid,
 783                              HRTIMER_MODE_ABS);
 784        __alarm_init(alarm, type, function);
 785}
 786
 787/**
 788 * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
 789 * @restart: ptr to restart block
 790 *
 791 * Handles restarted clock_nanosleep calls
 792 */
 793static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 794{
 795        enum  alarmtimer_type type = restart->nanosleep.clockid;
 796        ktime_t exp = restart->nanosleep.expires;
 797        struct alarm alarm;
 798
 799        alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 800
 801        return alarmtimer_do_nsleep(&alarm, exp, type);
 802}
 803
 804/**
 805 * alarm_timer_nsleep - alarmtimer nanosleep
 806 * @which_clock: clockid
 807 * @flags: determins abstime or relative
 808 * @tsreq: requested sleep time (abs or rel)
 809 * @rmtp: remaining sleep time saved
 810 *
 811 * Handles clock_nanosleep calls against _ALARM clockids
 812 */
 813static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 814                              const struct timespec64 *tsreq)
 815{
 816        enum  alarmtimer_type type = clock2alarm(which_clock);
 817        struct restart_block *restart = &current->restart_block;
 818        struct alarm alarm;
 819        ktime_t exp;
 820        int ret = 0;
 821
 822        if (!alarmtimer_get_rtcdev())
 823                return -EOPNOTSUPP;
 824
 825        if (flags & ~TIMER_ABSTIME)
 826                return -EINVAL;
 827
 828        if (!capable(CAP_WAKE_ALARM))
 829                return -EPERM;
 830
 831        alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
 832
 833        exp = timespec64_to_ktime(*tsreq);
 834        /* Convert (if necessary) to absolute time */
 835        if (flags != TIMER_ABSTIME) {
 836                ktime_t now = alarm_bases[type].get_ktime();
 837
 838                exp = ktime_add_safe(now, exp);
 839        } else {
 840                exp = timens_ktime_to_host(which_clock, exp);
 841        }
 842
 843        ret = alarmtimer_do_nsleep(&alarm, exp, type);
 844        if (ret != -ERESTART_RESTARTBLOCK)
 845                return ret;
 846
 847        /* abs timers don't set remaining time or restart */
 848        if (flags == TIMER_ABSTIME)
 849                return -ERESTARTNOHAND;
 850
 851        restart->fn = alarm_timer_nsleep_restart;
 852        restart->nanosleep.clockid = type;
 853        restart->nanosleep.expires = exp;
 854        return ret;
 855}
 856
 857const struct k_clock alarm_clock = {
 858        .clock_getres           = alarm_clock_getres,
 859        .clock_get_ktime        = alarm_clock_get_ktime,
 860        .clock_get_timespec     = alarm_clock_get_timespec,
 861        .timer_create           = alarm_timer_create,
 862        .timer_set              = common_timer_set,
 863        .timer_del              = common_timer_del,
 864        .timer_get              = common_timer_get,
 865        .timer_arm              = alarm_timer_arm,
 866        .timer_rearm            = alarm_timer_rearm,
 867        .timer_forward          = alarm_timer_forward,
 868        .timer_remaining        = alarm_timer_remaining,
 869        .timer_try_to_cancel    = alarm_timer_try_to_cancel,
 870        .timer_wait_running     = alarm_timer_wait_running,
 871        .nsleep                 = alarm_timer_nsleep,
 872};
 873#endif /* CONFIG_POSIX_TIMERS */
 874
 875
 876/* Suspend hook structures */
 877static const struct dev_pm_ops alarmtimer_pm_ops = {
 878        .suspend = alarmtimer_suspend,
 879        .resume = alarmtimer_resume,
 880};
 881
 882static struct platform_driver alarmtimer_driver = {
 883        .driver = {
 884                .name = "alarmtimer",
 885                .pm = &alarmtimer_pm_ops,
 886        }
 887};
 888
 889static void get_boottime_timespec(struct timespec64 *tp)
 890{
 891        ktime_get_boottime_ts64(tp);
 892        timens_add_boottime(tp);
 893}
 894
 895/**
 896 * alarmtimer_init - Initialize alarm timer code
 897 *
 898 * This function initializes the alarm bases and registers
 899 * the posix clock ids.
 900 */
 901static int __init alarmtimer_init(void)
 902{
 903        int error;
 904        int i;
 905
 906        alarmtimer_rtc_timer_init();
 907
 908        /* Initialize alarm bases */
 909        alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 910        alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
 911        alarm_bases[ALARM_REALTIME].get_timespec = ktime_get_real_ts64,
 912        alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 913        alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
 914        alarm_bases[ALARM_BOOTTIME].get_timespec = get_boottime_timespec;
 915        for (i = 0; i < ALARM_NUMTYPE; i++) {
 916                timerqueue_init_head(&alarm_bases[i].timerqueue);
 917                spin_lock_init(&alarm_bases[i].lock);
 918        }
 919
 920        error = alarmtimer_rtc_interface_setup();
 921        if (error)
 922                return error;
 923
 924        error = platform_driver_register(&alarmtimer_driver);
 925        if (error)
 926                goto out_if;
 927
 928        return 0;
 929out_if:
 930        alarmtimer_rtc_interface_remove();
 931        return error;
 932}
 933device_initcall(alarmtimer_init);
 934