linux/kernel/time/timekeeping.c
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   1/*
   2 *  linux/kernel/time/timekeeping.c
   3 *
   4 *  Kernel timekeeping code and accessor functions
   5 *
   6 *  This code was moved from linux/kernel/timer.c.
   7 *  Please see that file for copyright and history logs.
   8 *
   9 */
  10
  11#include <linux/timekeeper_internal.h>
  12#include <linux/module.h>
  13#include <linux/interrupt.h>
  14#include <linux/percpu.h>
  15#include <linux/init.h>
  16#include <linux/mm.h>
  17#include <linux/sched.h>
  18#include <linux/syscore_ops.h>
  19#include <linux/clocksource.h>
  20#include <linux/jiffies.h>
  21#include <linux/time.h>
  22#include <linux/tick.h>
  23#include <linux/stop_machine.h>
  24
  25
  26static struct timekeeper timekeeper;
  27
  28/*
  29 * This read-write spinlock protects us from races in SMP while
  30 * playing with xtime.
  31 */
  32__cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
  33
  34/* flag for if timekeeping is suspended */
  35int __read_mostly timekeeping_suspended;
  36
  37static inline void tk_normalize_xtime(struct timekeeper *tk)
  38{
  39        while (tk->xtime_nsec >= ((u64)NSEC_PER_SEC << tk->shift)) {
  40                tk->xtime_nsec -= (u64)NSEC_PER_SEC << tk->shift;
  41                tk->xtime_sec++;
  42        }
  43}
  44
  45static void tk_set_xtime(struct timekeeper *tk, const struct timespec *ts)
  46{
  47        tk->xtime_sec = ts->tv_sec;
  48        tk->xtime_nsec = (u64)ts->tv_nsec << tk->shift;
  49}
  50
  51static void tk_xtime_add(struct timekeeper *tk, const struct timespec *ts)
  52{
  53        tk->xtime_sec += ts->tv_sec;
  54        tk->xtime_nsec += (u64)ts->tv_nsec << tk->shift;
  55        tk_normalize_xtime(tk);
  56}
  57
  58static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec wtm)
  59{
  60        struct timespec tmp;
  61
  62        /*
  63         * Verify consistency of: offset_real = -wall_to_monotonic
  64         * before modifying anything
  65         */
  66        set_normalized_timespec(&tmp, -tk->wall_to_monotonic.tv_sec,
  67                                        -tk->wall_to_monotonic.tv_nsec);
  68        WARN_ON_ONCE(tk->offs_real.tv64 != timespec_to_ktime(tmp).tv64);
  69        tk->wall_to_monotonic = wtm;
  70        set_normalized_timespec(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
  71        tk->offs_real = timespec_to_ktime(tmp);
  72}
  73
  74static void tk_set_sleep_time(struct timekeeper *tk, struct timespec t)
  75{
  76        /* Verify consistency before modifying */
  77        WARN_ON_ONCE(tk->offs_boot.tv64 != timespec_to_ktime(tk->total_sleep_time).tv64);
  78
  79        tk->total_sleep_time    = t;
  80        tk->offs_boot           = timespec_to_ktime(t);
  81}
  82
  83/**
  84 * timekeeper_setup_internals - Set up internals to use clocksource clock.
  85 *
  86 * @clock:              Pointer to clocksource.
  87 *
  88 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
  89 * pair and interval request.
  90 *
  91 * Unless you're the timekeeping code, you should not be using this!
  92 */
  93static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
  94{
  95        cycle_t interval;
  96        u64 tmp, ntpinterval;
  97        struct clocksource *old_clock;
  98
  99        old_clock = tk->clock;
 100        tk->clock = clock;
 101        clock->cycle_last = clock->read(clock);
 102
 103        /* Do the ns -> cycle conversion first, using original mult */
 104        tmp = NTP_INTERVAL_LENGTH;
 105        tmp <<= clock->shift;
 106        ntpinterval = tmp;
 107        tmp += clock->mult/2;
 108        do_div(tmp, clock->mult);
 109        if (tmp == 0)
 110                tmp = 1;
 111
 112        interval = (cycle_t) tmp;
 113        tk->cycle_interval = interval;
 114
 115        /* Go back from cycles -> shifted ns */
 116        tk->xtime_interval = (u64) interval * clock->mult;
 117        tk->xtime_remainder = ntpinterval - tk->xtime_interval;
 118        tk->raw_interval =
 119                ((u64) interval * clock->mult) >> clock->shift;
 120
 121         /* if changing clocks, convert xtime_nsec shift units */
 122        if (old_clock) {
 123                int shift_change = clock->shift - old_clock->shift;
 124                if (shift_change < 0)
 125                        tk->xtime_nsec >>= -shift_change;
 126                else
 127                        tk->xtime_nsec <<= shift_change;
 128        }
 129        tk->shift = clock->shift;
 130
 131        tk->ntp_error = 0;
 132        tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
 133
 134        /*
 135         * The timekeeper keeps its own mult values for the currently
 136         * active clocksource. These value will be adjusted via NTP
 137         * to counteract clock drifting.
 138         */
 139        tk->mult = clock->mult;
 140}
 141
 142/* Timekeeper helper functions. */
 143static inline s64 timekeeping_get_ns(struct timekeeper *tk)
 144{
 145        cycle_t cycle_now, cycle_delta;
 146        struct clocksource *clock;
 147        s64 nsec;
 148
 149        /* read clocksource: */
 150        clock = tk->clock;
 151        cycle_now = clock->read(clock);
 152
 153        /* calculate the delta since the last update_wall_time: */
 154        cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
 155
 156        nsec = cycle_delta * tk->mult + tk->xtime_nsec;
 157        nsec >>= tk->shift;
 158
 159        /* If arch requires, add in gettimeoffset() */
 160        return nsec + arch_gettimeoffset();
 161}
 162
 163static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk)
 164{
 165        cycle_t cycle_now, cycle_delta;
 166        struct clocksource *clock;
 167        s64 nsec;
 168
 169        /* read clocksource: */
 170        clock = tk->clock;
 171        cycle_now = clock->read(clock);
 172
 173        /* calculate the delta since the last update_wall_time: */
 174        cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
 175
 176        /* convert delta to nanoseconds. */
 177        nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
 178
 179        /* If arch requires, add in gettimeoffset() */
 180        return nsec + arch_gettimeoffset();
 181}
 182
 183/* must hold write on timekeeper.lock */
 184static void timekeeping_update(struct timekeeper *tk, bool clearntp)
 185{
 186        if (clearntp) {
 187                tk->ntp_error = 0;
 188                ntp_clear();
 189        }
 190        update_vsyscall(tk);
 191}
 192
 193/**
 194 * timekeeping_forward_now - update clock to the current time
 195 *
 196 * Forward the current clock to update its state since the last call to
 197 * update_wall_time(). This is useful before significant clock changes,
 198 * as it avoids having to deal with this time offset explicitly.
 199 */
 200static void timekeeping_forward_now(struct timekeeper *tk)
 201{
 202        cycle_t cycle_now, cycle_delta;
 203        struct clocksource *clock;
 204        s64 nsec;
 205
 206        clock = tk->clock;
 207        cycle_now = clock->read(clock);
 208        cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
 209        clock->cycle_last = cycle_now;
 210
 211        tk->xtime_nsec += cycle_delta * tk->mult;
 212
 213        /* If arch requires, add in gettimeoffset() */
 214        tk->xtime_nsec += (u64)arch_gettimeoffset() << tk->shift;
 215
 216        tk_normalize_xtime(tk);
 217
 218        nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
 219        timespec_add_ns(&tk->raw_time, nsec);
 220}
 221
 222/**
 223 * getnstimeofday - Returns the time of day in a timespec
 224 * @ts:         pointer to the timespec to be set
 225 *
 226 * Returns the time of day in a timespec.
 227 */
 228void getnstimeofday(struct timespec *ts)
 229{
 230        struct timekeeper *tk = &timekeeper;
 231        unsigned long seq;
 232        s64 nsecs = 0;
 233
 234        WARN_ON(timekeeping_suspended);
 235
 236        do {
 237                seq = read_seqbegin(&tk->lock);
 238
 239                ts->tv_sec = tk->xtime_sec;
 240                nsecs = timekeeping_get_ns(tk);
 241
 242        } while (read_seqretry(&tk->lock, seq));
 243
 244        ts->tv_nsec = 0;
 245        timespec_add_ns(ts, nsecs);
 246}
 247EXPORT_SYMBOL(getnstimeofday);
 248
 249ktime_t ktime_get(void)
 250{
 251        struct timekeeper *tk = &timekeeper;
 252        unsigned int seq;
 253        s64 secs, nsecs;
 254
 255        WARN_ON(timekeeping_suspended);
 256
 257        do {
 258                seq = read_seqbegin(&tk->lock);
 259                secs = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
 260                nsecs = timekeeping_get_ns(tk) + tk->wall_to_monotonic.tv_nsec;
 261
 262        } while (read_seqretry(&tk->lock, seq));
 263        /*
 264         * Use ktime_set/ktime_add_ns to create a proper ktime on
 265         * 32-bit architectures without CONFIG_KTIME_SCALAR.
 266         */
 267        return ktime_add_ns(ktime_set(secs, 0), nsecs);
 268}
 269EXPORT_SYMBOL_GPL(ktime_get);
 270
 271/**
 272 * ktime_get_ts - get the monotonic clock in timespec format
 273 * @ts:         pointer to timespec variable
 274 *
 275 * The function calculates the monotonic clock from the realtime
 276 * clock and the wall_to_monotonic offset and stores the result
 277 * in normalized timespec format in the variable pointed to by @ts.
 278 */
 279void ktime_get_ts(struct timespec *ts)
 280{
 281        struct timekeeper *tk = &timekeeper;
 282        struct timespec tomono;
 283        s64 nsec;
 284        unsigned int seq;
 285
 286        WARN_ON(timekeeping_suspended);
 287
 288        do {
 289                seq = read_seqbegin(&tk->lock);
 290                ts->tv_sec = tk->xtime_sec;
 291                nsec = timekeeping_get_ns(tk);
 292                tomono = tk->wall_to_monotonic;
 293
 294        } while (read_seqretry(&tk->lock, seq));
 295
 296        ts->tv_sec += tomono.tv_sec;
 297        ts->tv_nsec = 0;
 298        timespec_add_ns(ts, nsec + tomono.tv_nsec);
 299}
 300EXPORT_SYMBOL_GPL(ktime_get_ts);
 301
 302#ifdef CONFIG_NTP_PPS
 303
 304/**
 305 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
 306 * @ts_raw:     pointer to the timespec to be set to raw monotonic time
 307 * @ts_real:    pointer to the timespec to be set to the time of day
 308 *
 309 * This function reads both the time of day and raw monotonic time at the
 310 * same time atomically and stores the resulting timestamps in timespec
 311 * format.
 312 */
 313void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
 314{
 315        struct timekeeper *tk = &timekeeper;
 316        unsigned long seq;
 317        s64 nsecs_raw, nsecs_real;
 318
 319        WARN_ON_ONCE(timekeeping_suspended);
 320
 321        do {
 322                seq = read_seqbegin(&tk->lock);
 323
 324                *ts_raw = tk->raw_time;
 325                ts_real->tv_sec = tk->xtime_sec;
 326                ts_real->tv_nsec = 0;
 327
 328                nsecs_raw = timekeeping_get_ns_raw(tk);
 329                nsecs_real = timekeeping_get_ns(tk);
 330
 331        } while (read_seqretry(&tk->lock, seq));
 332
 333        timespec_add_ns(ts_raw, nsecs_raw);
 334        timespec_add_ns(ts_real, nsecs_real);
 335}
 336EXPORT_SYMBOL(getnstime_raw_and_real);
 337
 338#endif /* CONFIG_NTP_PPS */
 339
 340/**
 341 * do_gettimeofday - Returns the time of day in a timeval
 342 * @tv:         pointer to the timeval to be set
 343 *
 344 * NOTE: Users should be converted to using getnstimeofday()
 345 */
 346void do_gettimeofday(struct timeval *tv)
 347{
 348        struct timespec now;
 349
 350        getnstimeofday(&now);
 351        tv->tv_sec = now.tv_sec;
 352        tv->tv_usec = now.tv_nsec/1000;
 353}
 354EXPORT_SYMBOL(do_gettimeofday);
 355
 356/**
 357 * do_settimeofday - Sets the time of day
 358 * @tv:         pointer to the timespec variable containing the new time
 359 *
 360 * Sets the time of day to the new time and update NTP and notify hrtimers
 361 */
 362int do_settimeofday(const struct timespec *tv)
 363{
 364        struct timekeeper *tk = &timekeeper;
 365        struct timespec ts_delta, xt;
 366        unsigned long flags;
 367
 368        if (!timespec_valid_strict(tv))
 369                return -EINVAL;
 370
 371        write_seqlock_irqsave(&tk->lock, flags);
 372
 373        timekeeping_forward_now(tk);
 374
 375        xt = tk_xtime(tk);
 376        ts_delta.tv_sec = tv->tv_sec - xt.tv_sec;
 377        ts_delta.tv_nsec = tv->tv_nsec - xt.tv_nsec;
 378
 379        tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, ts_delta));
 380
 381        tk_set_xtime(tk, tv);
 382
 383        timekeeping_update(tk, true);
 384
 385        write_sequnlock_irqrestore(&tk->lock, flags);
 386
 387        /* signal hrtimers about time change */
 388        clock_was_set();
 389
 390        return 0;
 391}
 392EXPORT_SYMBOL(do_settimeofday);
 393
 394/**
 395 * timekeeping_inject_offset - Adds or subtracts from the current time.
 396 * @tv:         pointer to the timespec variable containing the offset
 397 *
 398 * Adds or subtracts an offset value from the current time.
 399 */
 400int timekeeping_inject_offset(struct timespec *ts)
 401{
 402        struct timekeeper *tk = &timekeeper;
 403        unsigned long flags;
 404        struct timespec tmp;
 405        int ret = 0;
 406
 407        if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
 408                return -EINVAL;
 409
 410        write_seqlock_irqsave(&tk->lock, flags);
 411
 412        timekeeping_forward_now(tk);
 413
 414        /* Make sure the proposed value is valid */
 415        tmp = timespec_add(tk_xtime(tk),  *ts);
 416        if (!timespec_valid_strict(&tmp)) {
 417                ret = -EINVAL;
 418                goto error;
 419        }
 420
 421        tk_xtime_add(tk, ts);
 422        tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *ts));
 423
 424error: /* even if we error out, we forwarded the time, so call update */
 425        timekeeping_update(tk, true);
 426
 427        write_sequnlock_irqrestore(&tk->lock, flags);
 428
 429        /* signal hrtimers about time change */
 430        clock_was_set();
 431
 432        return ret;
 433}
 434EXPORT_SYMBOL(timekeeping_inject_offset);
 435
 436/**
 437 * change_clocksource - Swaps clocksources if a new one is available
 438 *
 439 * Accumulates current time interval and initializes new clocksource
 440 */
 441static int change_clocksource(void *data)
 442{
 443        struct timekeeper *tk = &timekeeper;
 444        struct clocksource *new, *old;
 445        unsigned long flags;
 446
 447        new = (struct clocksource *) data;
 448
 449        write_seqlock_irqsave(&tk->lock, flags);
 450
 451        timekeeping_forward_now(tk);
 452        if (!new->enable || new->enable(new) == 0) {
 453                old = tk->clock;
 454                tk_setup_internals(tk, new);
 455                if (old->disable)
 456                        old->disable(old);
 457        }
 458        timekeeping_update(tk, true);
 459
 460        write_sequnlock_irqrestore(&tk->lock, flags);
 461
 462        return 0;
 463}
 464
 465/**
 466 * timekeeping_notify - Install a new clock source
 467 * @clock:              pointer to the clock source
 468 *
 469 * This function is called from clocksource.c after a new, better clock
 470 * source has been registered. The caller holds the clocksource_mutex.
 471 */
 472void timekeeping_notify(struct clocksource *clock)
 473{
 474        struct timekeeper *tk = &timekeeper;
 475
 476        if (tk->clock == clock)
 477                return;
 478        stop_machine(change_clocksource, clock, NULL);
 479        tick_clock_notify();
 480}
 481
 482/**
 483 * ktime_get_real - get the real (wall-) time in ktime_t format
 484 *
 485 * returns the time in ktime_t format
 486 */
 487ktime_t ktime_get_real(void)
 488{
 489        struct timespec now;
 490
 491        getnstimeofday(&now);
 492
 493        return timespec_to_ktime(now);
 494}
 495EXPORT_SYMBOL_GPL(ktime_get_real);
 496
 497/**
 498 * getrawmonotonic - Returns the raw monotonic time in a timespec
 499 * @ts:         pointer to the timespec to be set
 500 *
 501 * Returns the raw monotonic time (completely un-modified by ntp)
 502 */
 503void getrawmonotonic(struct timespec *ts)
 504{
 505        struct timekeeper *tk = &timekeeper;
 506        unsigned long seq;
 507        s64 nsecs;
 508
 509        do {
 510                seq = read_seqbegin(&tk->lock);
 511                nsecs = timekeeping_get_ns_raw(tk);
 512                *ts = tk->raw_time;
 513
 514        } while (read_seqretry(&tk->lock, seq));
 515
 516        timespec_add_ns(ts, nsecs);
 517}
 518EXPORT_SYMBOL(getrawmonotonic);
 519
 520/**
 521 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
 522 */
 523int timekeeping_valid_for_hres(void)
 524{
 525        struct timekeeper *tk = &timekeeper;
 526        unsigned long seq;
 527        int ret;
 528
 529        do {
 530                seq = read_seqbegin(&tk->lock);
 531
 532                ret = tk->clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
 533
 534        } while (read_seqretry(&tk->lock, seq));
 535
 536        return ret;
 537}
 538
 539/**
 540 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
 541 */
 542u64 timekeeping_max_deferment(void)
 543{
 544        struct timekeeper *tk = &timekeeper;
 545        unsigned long seq;
 546        u64 ret;
 547
 548        do {
 549                seq = read_seqbegin(&tk->lock);
 550
 551                ret = tk->clock->max_idle_ns;
 552
 553        } while (read_seqretry(&tk->lock, seq));
 554
 555        return ret;
 556}
 557
 558/**
 559 * read_persistent_clock -  Return time from the persistent clock.
 560 *
 561 * Weak dummy function for arches that do not yet support it.
 562 * Reads the time from the battery backed persistent clock.
 563 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
 564 *
 565 *  XXX - Do be sure to remove it once all arches implement it.
 566 */
 567void __attribute__((weak)) read_persistent_clock(struct timespec *ts)
 568{
 569        ts->tv_sec = 0;
 570        ts->tv_nsec = 0;
 571}
 572
 573/**
 574 * read_boot_clock -  Return time of the system start.
 575 *
 576 * Weak dummy function for arches that do not yet support it.
 577 * Function to read the exact time the system has been started.
 578 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
 579 *
 580 *  XXX - Do be sure to remove it once all arches implement it.
 581 */
 582void __attribute__((weak)) read_boot_clock(struct timespec *ts)
 583{
 584        ts->tv_sec = 0;
 585        ts->tv_nsec = 0;
 586}
 587
 588/*
 589 * timekeeping_init - Initializes the clocksource and common timekeeping values
 590 */
 591void __init timekeeping_init(void)
 592{
 593        struct timekeeper *tk = &timekeeper;
 594        struct clocksource *clock;
 595        unsigned long flags;
 596        struct timespec now, boot, tmp;
 597
 598        read_persistent_clock(&now);
 599        if (!timespec_valid_strict(&now)) {
 600                pr_warn("WARNING: Persistent clock returned invalid value!\n"
 601                        "         Check your CMOS/BIOS settings.\n");
 602                now.tv_sec = 0;
 603                now.tv_nsec = 0;
 604        }
 605
 606        read_boot_clock(&boot);
 607        if (!timespec_valid_strict(&boot)) {
 608                pr_warn("WARNING: Boot clock returned invalid value!\n"
 609                        "         Check your CMOS/BIOS settings.\n");
 610                boot.tv_sec = 0;
 611                boot.tv_nsec = 0;
 612        }
 613
 614        seqlock_init(&tk->lock);
 615
 616        ntp_init();
 617
 618        write_seqlock_irqsave(&tk->lock, flags);
 619        clock = clocksource_default_clock();
 620        if (clock->enable)
 621                clock->enable(clock);
 622        tk_setup_internals(tk, clock);
 623
 624        tk_set_xtime(tk, &now);
 625        tk->raw_time.tv_sec = 0;
 626        tk->raw_time.tv_nsec = 0;
 627        if (boot.tv_sec == 0 && boot.tv_nsec == 0)
 628                boot = tk_xtime(tk);
 629
 630        set_normalized_timespec(&tmp, -boot.tv_sec, -boot.tv_nsec);
 631        tk_set_wall_to_mono(tk, tmp);
 632
 633        tmp.tv_sec = 0;
 634        tmp.tv_nsec = 0;
 635        tk_set_sleep_time(tk, tmp);
 636
 637        write_sequnlock_irqrestore(&tk->lock, flags);
 638}
 639
 640/* time in seconds when suspend began */
 641static struct timespec timekeeping_suspend_time;
 642
 643/**
 644 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
 645 * @delta: pointer to a timespec delta value
 646 *
 647 * Takes a timespec offset measuring a suspend interval and properly
 648 * adds the sleep offset to the timekeeping variables.
 649 */
 650static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
 651                                                        struct timespec *delta)
 652{
 653        if (!timespec_valid_strict(delta)) {
 654                printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
 655                                        "sleep delta value!\n");
 656                return;
 657        }
 658        tk_xtime_add(tk, delta);
 659        tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *delta));
 660        tk_set_sleep_time(tk, timespec_add(tk->total_sleep_time, *delta));
 661}
 662
 663/**
 664 * timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values
 665 * @delta: pointer to a timespec delta value
 666 *
 667 * This hook is for architectures that cannot support read_persistent_clock
 668 * because their RTC/persistent clock is only accessible when irqs are enabled.
 669 *
 670 * This function should only be called by rtc_resume(), and allows
 671 * a suspend offset to be injected into the timekeeping values.
 672 */
 673void timekeeping_inject_sleeptime(struct timespec *delta)
 674{
 675        struct timekeeper *tk = &timekeeper;
 676        unsigned long flags;
 677        struct timespec ts;
 678
 679        /* Make sure we don't set the clock twice */
 680        read_persistent_clock(&ts);
 681        if (!(ts.tv_sec == 0 && ts.tv_nsec == 0))
 682                return;
 683
 684        write_seqlock_irqsave(&tk->lock, flags);
 685
 686        timekeeping_forward_now(tk);
 687
 688        __timekeeping_inject_sleeptime(tk, delta);
 689
 690        timekeeping_update(tk, true);
 691
 692        write_sequnlock_irqrestore(&tk->lock, flags);
 693
 694        /* signal hrtimers about time change */
 695        clock_was_set();
 696}
 697
 698/**
 699 * timekeeping_resume - Resumes the generic timekeeping subsystem.
 700 *
 701 * This is for the generic clocksource timekeeping.
 702 * xtime/wall_to_monotonic/jiffies/etc are
 703 * still managed by arch specific suspend/resume code.
 704 */
 705static void timekeeping_resume(void)
 706{
 707        struct timekeeper *tk = &timekeeper;
 708        unsigned long flags;
 709        struct timespec ts;
 710
 711        read_persistent_clock(&ts);
 712
 713        clockevents_resume();
 714        clocksource_resume();
 715
 716        write_seqlock_irqsave(&tk->lock, flags);
 717
 718        if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) {
 719                ts = timespec_sub(ts, timekeeping_suspend_time);
 720                __timekeeping_inject_sleeptime(tk, &ts);
 721        }
 722        /* re-base the last cycle value */
 723        tk->clock->cycle_last = tk->clock->read(tk->clock);
 724        tk->ntp_error = 0;
 725        timekeeping_suspended = 0;
 726        timekeeping_update(tk, false);
 727        write_sequnlock_irqrestore(&tk->lock, flags);
 728
 729        touch_softlockup_watchdog();
 730
 731        clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
 732
 733        /* Resume hrtimers */
 734        hrtimers_resume();
 735}
 736
 737static int timekeeping_suspend(void)
 738{
 739        struct timekeeper *tk = &timekeeper;
 740        unsigned long flags;
 741        struct timespec         delta, delta_delta;
 742        static struct timespec  old_delta;
 743
 744        read_persistent_clock(&timekeeping_suspend_time);
 745
 746        write_seqlock_irqsave(&tk->lock, flags);
 747        timekeeping_forward_now(tk);
 748        timekeeping_suspended = 1;
 749
 750        /*
 751         * To avoid drift caused by repeated suspend/resumes,
 752         * which each can add ~1 second drift error,
 753         * try to compensate so the difference in system time
 754         * and persistent_clock time stays close to constant.
 755         */
 756        delta = timespec_sub(tk_xtime(tk), timekeeping_suspend_time);
 757        delta_delta = timespec_sub(delta, old_delta);
 758        if (abs(delta_delta.tv_sec)  >= 2) {
 759                /*
 760                 * if delta_delta is too large, assume time correction
 761                 * has occured and set old_delta to the current delta.
 762                 */
 763                old_delta = delta;
 764        } else {
 765                /* Otherwise try to adjust old_system to compensate */
 766                timekeeping_suspend_time =
 767                        timespec_add(timekeeping_suspend_time, delta_delta);
 768        }
 769        write_sequnlock_irqrestore(&tk->lock, flags);
 770
 771        clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
 772        clocksource_suspend();
 773        clockevents_suspend();
 774
 775        return 0;
 776}
 777
 778/* sysfs resume/suspend bits for timekeeping */
 779static struct syscore_ops timekeeping_syscore_ops = {
 780        .resume         = timekeeping_resume,
 781        .suspend        = timekeeping_suspend,
 782};
 783
 784static int __init timekeeping_init_ops(void)
 785{
 786        register_syscore_ops(&timekeeping_syscore_ops);
 787        return 0;
 788}
 789
 790device_initcall(timekeeping_init_ops);
 791
 792/*
 793 * If the error is already larger, we look ahead even further
 794 * to compensate for late or lost adjustments.
 795 */
 796static __always_inline int timekeeping_bigadjust(struct timekeeper *tk,
 797                                                 s64 error, s64 *interval,
 798                                                 s64 *offset)
 799{
 800        s64 tick_error, i;
 801        u32 look_ahead, adj;
 802        s32 error2, mult;
 803
 804        /*
 805         * Use the current error value to determine how much to look ahead.
 806         * The larger the error the slower we adjust for it to avoid problems
 807         * with losing too many ticks, otherwise we would overadjust and
 808         * produce an even larger error.  The smaller the adjustment the
 809         * faster we try to adjust for it, as lost ticks can do less harm
 810         * here.  This is tuned so that an error of about 1 msec is adjusted
 811         * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
 812         */
 813        error2 = tk->ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
 814        error2 = abs(error2);
 815        for (look_ahead = 0; error2 > 0; look_ahead++)
 816                error2 >>= 2;
 817
 818        /*
 819         * Now calculate the error in (1 << look_ahead) ticks, but first
 820         * remove the single look ahead already included in the error.
 821         */
 822        tick_error = ntp_tick_length() >> (tk->ntp_error_shift + 1);
 823        tick_error -= tk->xtime_interval >> 1;
 824        error = ((error - tick_error) >> look_ahead) + tick_error;
 825
 826        /* Finally calculate the adjustment shift value.  */
 827        i = *interval;
 828        mult = 1;
 829        if (error < 0) {
 830                error = -error;
 831                *interval = -*interval;
 832                *offset = -*offset;
 833                mult = -1;
 834        }
 835        for (adj = 0; error > i; adj++)
 836                error >>= 1;
 837
 838        *interval <<= adj;
 839        *offset <<= adj;
 840        return mult << adj;
 841}
 842
 843/*
 844 * Adjust the multiplier to reduce the error value,
 845 * this is optimized for the most common adjustments of -1,0,1,
 846 * for other values we can do a bit more work.
 847 */
 848static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
 849{
 850        s64 error, interval = tk->cycle_interval;
 851        int adj;
 852
 853        /*
 854         * The point of this is to check if the error is greater than half
 855         * an interval.
 856         *
 857         * First we shift it down from NTP_SHIFT to clocksource->shifted nsecs.
 858         *
 859         * Note we subtract one in the shift, so that error is really error*2.
 860         * This "saves" dividing(shifting) interval twice, but keeps the
 861         * (error > interval) comparison as still measuring if error is
 862         * larger than half an interval.
 863         *
 864         * Note: It does not "save" on aggravation when reading the code.
 865         */
 866        error = tk->ntp_error >> (tk->ntp_error_shift - 1);
 867        if (error > interval) {
 868                /*
 869                 * We now divide error by 4(via shift), which checks if
 870                 * the error is greater than twice the interval.
 871                 * If it is greater, we need a bigadjust, if its smaller,
 872                 * we can adjust by 1.
 873                 */
 874                error >>= 2;
 875                /*
 876                 * XXX - In update_wall_time, we round up to the next
 877                 * nanosecond, and store the amount rounded up into
 878                 * the error. This causes the likely below to be unlikely.
 879                 *
 880                 * The proper fix is to avoid rounding up by using
 881                 * the high precision tk->xtime_nsec instead of
 882                 * xtime.tv_nsec everywhere. Fixing this will take some
 883                 * time.
 884                 */
 885                if (likely(error <= interval))
 886                        adj = 1;
 887                else
 888                        adj = timekeeping_bigadjust(tk, error, &interval, &offset);
 889        } else {
 890                if (error < -interval) {
 891                        /* See comment above, this is just switched for the negative */
 892                        error >>= 2;
 893                        if (likely(error >= -interval)) {
 894                                adj = -1;
 895                                interval = -interval;
 896                                offset = -offset;
 897                        } else {
 898                                adj = timekeeping_bigadjust(tk, error, &interval, &offset);
 899                        }
 900                } else {
 901                        goto out_adjust;
 902                }
 903        }
 904
 905        if (unlikely(tk->clock->maxadj &&
 906                (tk->mult + adj > tk->clock->mult + tk->clock->maxadj))) {
 907                printk_once(KERN_WARNING
 908                        "Adjusting %s more than 11%% (%ld vs %ld)\n",
 909                        tk->clock->name, (long)tk->mult + adj,
 910                        (long)tk->clock->mult + tk->clock->maxadj);
 911        }
 912        /*
 913         * So the following can be confusing.
 914         *
 915         * To keep things simple, lets assume adj == 1 for now.
 916         *
 917         * When adj != 1, remember that the interval and offset values
 918         * have been appropriately scaled so the math is the same.
 919         *
 920         * The basic idea here is that we're increasing the multiplier
 921         * by one, this causes the xtime_interval to be incremented by
 922         * one cycle_interval. This is because:
 923         *      xtime_interval = cycle_interval * mult
 924         * So if mult is being incremented by one:
 925         *      xtime_interval = cycle_interval * (mult + 1)
 926         * Its the same as:
 927         *      xtime_interval = (cycle_interval * mult) + cycle_interval
 928         * Which can be shortened to:
 929         *      xtime_interval += cycle_interval
 930         *
 931         * So offset stores the non-accumulated cycles. Thus the current
 932         * time (in shifted nanoseconds) is:
 933         *      now = (offset * adj) + xtime_nsec
 934         * Now, even though we're adjusting the clock frequency, we have
 935         * to keep time consistent. In other words, we can't jump back
 936         * in time, and we also want to avoid jumping forward in time.
 937         *
 938         * So given the same offset value, we need the time to be the same
 939         * both before and after the freq adjustment.
 940         *      now = (offset * adj_1) + xtime_nsec_1
 941         *      now = (offset * adj_2) + xtime_nsec_2
 942         * So:
 943         *      (offset * adj_1) + xtime_nsec_1 =
 944         *              (offset * adj_2) + xtime_nsec_2
 945         * And we know:
 946         *      adj_2 = adj_1 + 1
 947         * So:
 948         *      (offset * adj_1) + xtime_nsec_1 =
 949         *              (offset * (adj_1+1)) + xtime_nsec_2
 950         *      (offset * adj_1) + xtime_nsec_1 =
 951         *              (offset * adj_1) + offset + xtime_nsec_2
 952         * Canceling the sides:
 953         *      xtime_nsec_1 = offset + xtime_nsec_2
 954         * Which gives us:
 955         *      xtime_nsec_2 = xtime_nsec_1 - offset
 956         * Which simplfies to:
 957         *      xtime_nsec -= offset
 958         *
 959         * XXX - TODO: Doc ntp_error calculation.
 960         */
 961        tk->mult += adj;
 962        tk->xtime_interval += interval;
 963        tk->xtime_nsec -= offset;
 964        tk->ntp_error -= (interval - offset) << tk->ntp_error_shift;
 965
 966out_adjust:
 967        /*
 968         * It may be possible that when we entered this function, xtime_nsec
 969         * was very small.  Further, if we're slightly speeding the clocksource
 970         * in the code above, its possible the required corrective factor to
 971         * xtime_nsec could cause it to underflow.
 972         *
 973         * Now, since we already accumulated the second, cannot simply roll
 974         * the accumulated second back, since the NTP subsystem has been
 975         * notified via second_overflow. So instead we push xtime_nsec forward
 976         * by the amount we underflowed, and add that amount into the error.
 977         *
 978         * We'll correct this error next time through this function, when
 979         * xtime_nsec is not as small.
 980         */
 981        if (unlikely((s64)tk->xtime_nsec < 0)) {
 982                s64 neg = -(s64)tk->xtime_nsec;
 983                tk->xtime_nsec = 0;
 984                tk->ntp_error += neg << tk->ntp_error_shift;
 985        }
 986
 987}
 988
 989/**
 990 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
 991 *
 992 * Helper function that accumulates a the nsecs greater then a second
 993 * from the xtime_nsec field to the xtime_secs field.
 994 * It also calls into the NTP code to handle leapsecond processing.
 995 *
 996 */
 997static inline void accumulate_nsecs_to_secs(struct timekeeper *tk)
 998{
 999        u64 nsecps = (u64)NSEC_PER_SEC << tk->shift;
1000
1001        while (tk->xtime_nsec >= nsecps) {
1002                int leap;
1003
1004                tk->xtime_nsec -= nsecps;
1005                tk->xtime_sec++;
1006
1007                /* Figure out if its a leap sec and apply if needed */
1008                leap = second_overflow(tk->xtime_sec);
1009                if (unlikely(leap)) {
1010                        struct timespec ts;
1011
1012                        tk->xtime_sec += leap;
1013
1014                        ts.tv_sec = leap;
1015                        ts.tv_nsec = 0;
1016                        tk_set_wall_to_mono(tk,
1017                                timespec_sub(tk->wall_to_monotonic, ts));
1018
1019                        clock_was_set_delayed();
1020                }
1021        }
1022}
1023
1024/**
1025 * logarithmic_accumulation - shifted accumulation of cycles
1026 *
1027 * This functions accumulates a shifted interval of cycles into
1028 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1029 * loop.
1030 *
1031 * Returns the unconsumed cycles.
1032 */
1033static cycle_t logarithmic_accumulation(struct timekeeper *tk, cycle_t offset,
1034                                                u32 shift)
1035{
1036        u64 raw_nsecs;
1037
1038        /* If the offset is smaller then a shifted interval, do nothing */
1039        if (offset < tk->cycle_interval<<shift)
1040                return offset;
1041
1042        /* Accumulate one shifted interval */
1043        offset -= tk->cycle_interval << shift;
1044        tk->clock->cycle_last += tk->cycle_interval << shift;
1045
1046        tk->xtime_nsec += tk->xtime_interval << shift;
1047        accumulate_nsecs_to_secs(tk);
1048
1049        /* Accumulate raw time */
1050        raw_nsecs = (u64)tk->raw_interval << shift;
1051        raw_nsecs += tk->raw_time.tv_nsec;
1052        if (raw_nsecs >= NSEC_PER_SEC) {
1053                u64 raw_secs = raw_nsecs;
1054                raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
1055                tk->raw_time.tv_sec += raw_secs;
1056        }
1057        tk->raw_time.tv_nsec = raw_nsecs;
1058
1059        /* Accumulate error between NTP and clock interval */
1060        tk->ntp_error += ntp_tick_length() << shift;
1061        tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
1062                                                (tk->ntp_error_shift + shift);
1063
1064        return offset;
1065}
1066
1067#ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
1068static inline void old_vsyscall_fixup(struct timekeeper *tk)
1069{
1070        s64 remainder;
1071
1072        /*
1073        * Store only full nanoseconds into xtime_nsec after rounding
1074        * it up and add the remainder to the error difference.
1075        * XXX - This is necessary to avoid small 1ns inconsistnecies caused
1076        * by truncating the remainder in vsyscalls. However, it causes
1077        * additional work to be done in timekeeping_adjust(). Once
1078        * the vsyscall implementations are converted to use xtime_nsec
1079        * (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
1080        * users are removed, this can be killed.
1081        */
1082        remainder = tk->xtime_nsec & ((1ULL << tk->shift) - 1);
1083        tk->xtime_nsec -= remainder;
1084        tk->xtime_nsec += 1ULL << tk->shift;
1085        tk->ntp_error += remainder << tk->ntp_error_shift;
1086
1087}
1088#else
1089#define old_vsyscall_fixup(tk)
1090#endif
1091
1092
1093
1094/**
1095 * update_wall_time - Uses the current clocksource to increment the wall time
1096 *
1097 */
1098static void update_wall_time(void)
1099{
1100        struct clocksource *clock;
1101        struct timekeeper *tk = &timekeeper;
1102        cycle_t offset;
1103        int shift = 0, maxshift;
1104        unsigned long flags;
1105
1106        write_seqlock_irqsave(&tk->lock, flags);
1107
1108        /* Make sure we're fully resumed: */
1109        if (unlikely(timekeeping_suspended))
1110                goto out;
1111
1112        clock = tk->clock;
1113
1114#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1115        offset = tk->cycle_interval;
1116#else
1117        offset = (clock->read(clock) - clock->cycle_last) & clock->mask;
1118#endif
1119
1120        /* Check if there's really nothing to do */
1121        if (offset < tk->cycle_interval)
1122                goto out;
1123
1124        /*
1125         * With NO_HZ we may have to accumulate many cycle_intervals
1126         * (think "ticks") worth of time at once. To do this efficiently,
1127         * we calculate the largest doubling multiple of cycle_intervals
1128         * that is smaller than the offset.  We then accumulate that
1129         * chunk in one go, and then try to consume the next smaller
1130         * doubled multiple.
1131         */
1132        shift = ilog2(offset) - ilog2(tk->cycle_interval);
1133        shift = max(0, shift);
1134        /* Bound shift to one less than what overflows tick_length */
1135        maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
1136        shift = min(shift, maxshift);
1137        while (offset >= tk->cycle_interval) {
1138                offset = logarithmic_accumulation(tk, offset, shift);
1139                if (offset < tk->cycle_interval<<shift)
1140                        shift--;
1141        }
1142
1143        /* correct the clock when NTP error is too big */
1144        timekeeping_adjust(tk, offset);
1145
1146        /*
1147         * XXX This can be killed once everyone converts
1148         * to the new update_vsyscall.
1149         */
1150        old_vsyscall_fixup(tk);
1151
1152        /*
1153         * Finally, make sure that after the rounding
1154         * xtime_nsec isn't larger than NSEC_PER_SEC
1155         */
1156        accumulate_nsecs_to_secs(tk);
1157
1158        timekeeping_update(tk, false);
1159
1160out:
1161        write_sequnlock_irqrestore(&tk->lock, flags);
1162
1163}
1164
1165/**
1166 * getboottime - Return the real time of system boot.
1167 * @ts:         pointer to the timespec to be set
1168 *
1169 * Returns the wall-time of boot in a timespec.
1170 *
1171 * This is based on the wall_to_monotonic offset and the total suspend
1172 * time. Calls to settimeofday will affect the value returned (which
1173 * basically means that however wrong your real time clock is at boot time,
1174 * you get the right time here).
1175 */
1176void getboottime(struct timespec *ts)
1177{
1178        struct timekeeper *tk = &timekeeper;
1179        struct timespec boottime = {
1180                .tv_sec = tk->wall_to_monotonic.tv_sec +
1181                                tk->total_sleep_time.tv_sec,
1182                .tv_nsec = tk->wall_to_monotonic.tv_nsec +
1183                                tk->total_sleep_time.tv_nsec
1184        };
1185
1186        set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec);
1187}
1188EXPORT_SYMBOL_GPL(getboottime);
1189
1190/**
1191 * get_monotonic_boottime - Returns monotonic time since boot
1192 * @ts:         pointer to the timespec to be set
1193 *
1194 * Returns the monotonic time since boot in a timespec.
1195 *
1196 * This is similar to CLOCK_MONTONIC/ktime_get_ts, but also
1197 * includes the time spent in suspend.
1198 */
1199void get_monotonic_boottime(struct timespec *ts)
1200{
1201        struct timekeeper *tk = &timekeeper;
1202        struct timespec tomono, sleep;
1203        s64 nsec;
1204        unsigned int seq;
1205
1206        WARN_ON(timekeeping_suspended);
1207
1208        do {
1209                seq = read_seqbegin(&tk->lock);
1210                ts->tv_sec = tk->xtime_sec;
1211                nsec = timekeeping_get_ns(tk);
1212                tomono = tk->wall_to_monotonic;
1213                sleep = tk->total_sleep_time;
1214
1215        } while (read_seqretry(&tk->lock, seq));
1216
1217        ts->tv_sec += tomono.tv_sec + sleep.tv_sec;
1218        ts->tv_nsec = 0;
1219        timespec_add_ns(ts, nsec + tomono.tv_nsec + sleep.tv_nsec);
1220}
1221EXPORT_SYMBOL_GPL(get_monotonic_boottime);
1222
1223/**
1224 * ktime_get_boottime - Returns monotonic time since boot in a ktime
1225 *
1226 * Returns the monotonic time since boot in a ktime
1227 *
1228 * This is similar to CLOCK_MONTONIC/ktime_get, but also
1229 * includes the time spent in suspend.
1230 */
1231ktime_t ktime_get_boottime(void)
1232{
1233        struct timespec ts;
1234
1235        get_monotonic_boottime(&ts);
1236        return timespec_to_ktime(ts);
1237}
1238EXPORT_SYMBOL_GPL(ktime_get_boottime);
1239
1240/**
1241 * monotonic_to_bootbased - Convert the monotonic time to boot based.
1242 * @ts:         pointer to the timespec to be converted
1243 */
1244void monotonic_to_bootbased(struct timespec *ts)
1245{
1246        struct timekeeper *tk = &timekeeper;
1247
1248        *ts = timespec_add(*ts, tk->total_sleep_time);
1249}
1250EXPORT_SYMBOL_GPL(monotonic_to_bootbased);
1251
1252unsigned long get_seconds(void)
1253{
1254        struct timekeeper *tk = &timekeeper;
1255
1256        return tk->xtime_sec;
1257}
1258EXPORT_SYMBOL(get_seconds);
1259
1260struct timespec __current_kernel_time(void)
1261{
1262        struct timekeeper *tk = &timekeeper;
1263
1264        return tk_xtime(tk);
1265}
1266
1267struct timespec current_kernel_time(void)
1268{
1269        struct timekeeper *tk = &timekeeper;
1270        struct timespec now;
1271        unsigned long seq;
1272
1273        do {
1274                seq = read_seqbegin(&tk->lock);
1275
1276                now = tk_xtime(tk);
1277        } while (read_seqretry(&tk->lock, seq));
1278
1279        return now;
1280}
1281EXPORT_SYMBOL(current_kernel_time);
1282
1283struct timespec get_monotonic_coarse(void)
1284{
1285        struct timekeeper *tk = &timekeeper;
1286        struct timespec now, mono;
1287        unsigned long seq;
1288
1289        do {
1290                seq = read_seqbegin(&tk->lock);
1291
1292                now = tk_xtime(tk);
1293                mono = tk->wall_to_monotonic;
1294        } while (read_seqretry(&tk->lock, seq));
1295
1296        set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
1297                                now.tv_nsec + mono.tv_nsec);
1298        return now;
1299}
1300
1301/*
1302 * The 64-bit jiffies value is not atomic - you MUST NOT read it
1303 * without sampling the sequence number in xtime_lock.
1304 * jiffies is defined in the linker script...
1305 */
1306void do_timer(unsigned long ticks)
1307{
1308        jiffies_64 += ticks;
1309        update_wall_time();
1310        calc_global_load(ticks);
1311}
1312
1313/**
1314 * get_xtime_and_monotonic_and_sleep_offset() - get xtime, wall_to_monotonic,
1315 *    and sleep offsets.
1316 * @xtim:       pointer to timespec to be set with xtime
1317 * @wtom:       pointer to timespec to be set with wall_to_monotonic
1318 * @sleep:      pointer to timespec to be set with time in suspend
1319 */
1320void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
1321                                struct timespec *wtom, struct timespec *sleep)
1322{
1323        struct timekeeper *tk = &timekeeper;
1324        unsigned long seq;
1325
1326        do {
1327                seq = read_seqbegin(&tk->lock);
1328                *xtim = tk_xtime(tk);
1329                *wtom = tk->wall_to_monotonic;
1330                *sleep = tk->total_sleep_time;
1331        } while (read_seqretry(&tk->lock, seq));
1332}
1333
1334#ifdef CONFIG_HIGH_RES_TIMERS
1335/**
1336 * ktime_get_update_offsets - hrtimer helper
1337 * @offs_real:  pointer to storage for monotonic -> realtime offset
1338 * @offs_boot:  pointer to storage for monotonic -> boottime offset
1339 *
1340 * Returns current monotonic time and updates the offsets
1341 * Called from hrtimer_interupt() or retrigger_next_event()
1342 */
1343ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot)
1344{
1345        struct timekeeper *tk = &timekeeper;
1346        ktime_t now;
1347        unsigned int seq;
1348        u64 secs, nsecs;
1349
1350        do {
1351                seq = read_seqbegin(&tk->lock);
1352
1353                secs = tk->xtime_sec;
1354                nsecs = timekeeping_get_ns(tk);
1355
1356                *offs_real = tk->offs_real;
1357                *offs_boot = tk->offs_boot;
1358        } while (read_seqretry(&tk->lock, seq));
1359
1360        now = ktime_add_ns(ktime_set(secs, 0), nsecs);
1361        now = ktime_sub(now, *offs_real);
1362        return now;
1363}
1364#endif
1365
1366/**
1367 * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
1368 */
1369ktime_t ktime_get_monotonic_offset(void)
1370{
1371        struct timekeeper *tk = &timekeeper;
1372        unsigned long seq;
1373        struct timespec wtom;
1374
1375        do {
1376                seq = read_seqbegin(&tk->lock);
1377                wtom = tk->wall_to_monotonic;
1378        } while (read_seqretry(&tk->lock, seq));
1379
1380        return timespec_to_ktime(wtom);
1381}
1382EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset);
1383
1384/**
1385 * xtime_update() - advances the timekeeping infrastructure
1386 * @ticks:      number of ticks, that have elapsed since the last call.
1387 *
1388 * Must be called with interrupts disabled.
1389 */
1390void xtime_update(unsigned long ticks)
1391{
1392        write_seqlock(&xtime_lock);
1393        do_timer(ticks);
1394        write_sequnlock(&xtime_lock);
1395}
1396
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