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/module.h>
  12#include <linux/interrupt.h>
  13#include <linux/percpu.h>
  14#include <linux/init.h>
  15#include <linux/mm.h>
  16#include <linux/sched.h>
  17#include <linux/syscore_ops.h>
  18#include <linux/clocksource.h>
  19#include <linux/jiffies.h>
  20#include <linux/time.h>
  21#include <linux/tick.h>
  22#include <linux/stop_machine.h>
  23
  24/* Structure holding internal timekeeping values. */
  25struct timekeeper {
  26        /* Current clocksource used for timekeeping. */
  27        struct clocksource      *clock;
  28        /* NTP adjusted clock multiplier */
  29        u32                     mult;
  30        /* The shift value of the current clocksource. */
  31        u32                     shift;
  32        /* Number of clock cycles in one NTP interval. */
  33        cycle_t                 cycle_interval;
  34        /* Number of clock shifted nano seconds in one NTP interval. */
  35        u64                     xtime_interval;
  36        /* shifted nano seconds left over when rounding cycle_interval */
  37        s64                     xtime_remainder;
  38        /* Raw nano seconds accumulated per NTP interval. */
  39        u32                     raw_interval;
  40
  41        /* Current CLOCK_REALTIME time in seconds */
  42        u64                     xtime_sec;
  43        /* Clock shifted nano seconds */
  44        u64                     xtime_nsec;
  45
  46        /* Difference between accumulated time and NTP time in ntp
  47         * shifted nano seconds. */
  48        s64                     ntp_error;
  49        /* Shift conversion between clock shifted nano seconds and
  50         * ntp shifted nano seconds. */
  51        u32                     ntp_error_shift;
  52
  53        /*
  54         * wall_to_monotonic is what we need to add to xtime (or xtime corrected
  55         * for sub jiffie times) to get to monotonic time.  Monotonic is pegged
  56         * at zero at system boot time, so wall_to_monotonic will be negative,
  57         * however, we will ALWAYS keep the tv_nsec part positive so we can use
  58         * the usual normalization.
  59         *
  60         * wall_to_monotonic is moved after resume from suspend for the
  61         * monotonic time not to jump. We need to add total_sleep_time to
  62         * wall_to_monotonic to get the real boot based time offset.
  63         *
  64         * - wall_to_monotonic is no longer the boot time, getboottime must be
  65         * used instead.
  66         */
  67        struct timespec         wall_to_monotonic;
  68        /* Offset clock monotonic -> clock realtime */
  69        ktime_t                 offs_real;
  70        /* time spent in suspend */
  71        struct timespec         total_sleep_time;
  72        /* Offset clock monotonic -> clock boottime */
  73        ktime_t                 offs_boot;
  74        /* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */
  75        struct timespec         raw_time;
  76        /* Seqlock for all timekeeper values */
  77        seqlock_t               lock;
  78};
  79
  80static struct timekeeper timekeeper;
  81
  82/*
  83 * This read-write spinlock protects us from races in SMP while
  84 * playing with xtime.
  85 */
  86__cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
  87
  88/* flag for if timekeeping is suspended */
  89int __read_mostly timekeeping_suspended;
  90
  91static inline void tk_normalize_xtime(struct timekeeper *tk)
  92{
  93        while (tk->xtime_nsec >= ((u64)NSEC_PER_SEC << tk->shift)) {
  94                tk->xtime_nsec -= (u64)NSEC_PER_SEC << tk->shift;
  95                tk->xtime_sec++;
  96        }
  97}
  98
  99static struct timespec tk_xtime(struct timekeeper *tk)
 100{
 101        struct timespec ts;
 102
 103        ts.tv_sec = tk->xtime_sec;
 104        ts.tv_nsec = (long)(tk->xtime_nsec >> tk->shift);
 105        return ts;
 106}
 107
 108static void tk_set_xtime(struct timekeeper *tk, const struct timespec *ts)
 109{
 110        tk->xtime_sec = ts->tv_sec;
 111        tk->xtime_nsec = (u64)ts->tv_nsec << tk->shift;
 112}
 113
 114static void tk_xtime_add(struct timekeeper *tk, const struct timespec *ts)
 115{
 116        tk->xtime_sec += ts->tv_sec;
 117        tk->xtime_nsec += (u64)ts->tv_nsec << tk->shift;
 118        tk_normalize_xtime(tk);
 119}
 120
 121static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec wtm)
 122{
 123        struct timespec tmp;
 124
 125        /*
 126         * Verify consistency of: offset_real = -wall_to_monotonic
 127         * before modifying anything
 128         */
 129        set_normalized_timespec(&tmp, -tk->wall_to_monotonic.tv_sec,
 130                                        -tk->wall_to_monotonic.tv_nsec);
 131        WARN_ON_ONCE(tk->offs_real.tv64 != timespec_to_ktime(tmp).tv64);
 132        tk->wall_to_monotonic = wtm;
 133        set_normalized_timespec(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
 134        tk->offs_real = timespec_to_ktime(tmp);
 135}
 136
 137static void tk_set_sleep_time(struct timekeeper *tk, struct timespec t)
 138{
 139        /* Verify consistency before modifying */
 140        WARN_ON_ONCE(tk->offs_boot.tv64 != timespec_to_ktime(tk->total_sleep_time).tv64);
 141
 142        tk->total_sleep_time    = t;
 143        tk->offs_boot           = timespec_to_ktime(t);
 144}
 145
 146/**
 147 * timekeeper_setup_internals - Set up internals to use clocksource clock.
 148 *
 149 * @clock:              Pointer to clocksource.
 150 *
 151 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
 152 * pair and interval request.
 153 *
 154 * Unless you're the timekeeping code, you should not be using this!
 155 */
 156static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
 157{
 158        cycle_t interval;
 159        u64 tmp, ntpinterval;
 160        struct clocksource *old_clock;
 161
 162        old_clock = tk->clock;
 163        tk->clock = clock;
 164        clock->cycle_last = clock->read(clock);
 165
 166        /* Do the ns -> cycle conversion first, using original mult */
 167        tmp = NTP_INTERVAL_LENGTH;
 168        tmp <<= clock->shift;
 169        ntpinterval = tmp;
 170        tmp += clock->mult/2;
 171        do_div(tmp, clock->mult);
 172        if (tmp == 0)
 173                tmp = 1;
 174
 175        interval = (cycle_t) tmp;
 176        tk->cycle_interval = interval;
 177
 178        /* Go back from cycles -> shifted ns */
 179        tk->xtime_interval = (u64) interval * clock->mult;
 180        tk->xtime_remainder = ntpinterval - tk->xtime_interval;
 181        tk->raw_interval =
 182                ((u64) interval * clock->mult) >> clock->shift;
 183
 184         /* if changing clocks, convert xtime_nsec shift units */
 185        if (old_clock) {
 186                int shift_change = clock->shift - old_clock->shift;
 187                if (shift_change < 0)
 188                        tk->xtime_nsec >>= -shift_change;
 189                else
 190                        tk->xtime_nsec <<= shift_change;
 191        }
 192        tk->shift = clock->shift;
 193
 194        tk->ntp_error = 0;
 195        tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
 196
 197        /*
 198         * The timekeeper keeps its own mult values for the currently
 199         * active clocksource. These value will be adjusted via NTP
 200         * to counteract clock drifting.
 201         */
 202        tk->mult = clock->mult;
 203}
 204
 205/* Timekeeper helper functions. */
 206static inline s64 timekeeping_get_ns(struct timekeeper *tk)
 207{
 208        cycle_t cycle_now, cycle_delta;
 209        struct clocksource *clock;
 210        s64 nsec;
 211
 212        /* read clocksource: */
 213        clock = tk->clock;
 214        cycle_now = clock->read(clock);
 215
 216        /* calculate the delta since the last update_wall_time: */
 217        cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
 218
 219        nsec = cycle_delta * tk->mult + tk->xtime_nsec;
 220        nsec >>= tk->shift;
 221
 222        /* If arch requires, add in gettimeoffset() */
 223        return nsec + arch_gettimeoffset();
 224}
 225
 226static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk)
 227{
 228        cycle_t cycle_now, cycle_delta;
 229        struct clocksource *clock;
 230        s64 nsec;
 231
 232        /* read clocksource: */
 233        clock = tk->clock;
 234        cycle_now = clock->read(clock);
 235
 236        /* calculate the delta since the last update_wall_time: */
 237        cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
 238
 239        /* convert delta to nanoseconds. */
 240        nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
 241
 242        /* If arch requires, add in gettimeoffset() */
 243        return nsec + arch_gettimeoffset();
 244}
 245
 246/* must hold write on timekeeper.lock */
 247static void timekeeping_update(struct timekeeper *tk, bool clearntp)
 248{
 249        struct timespec xt;
 250
 251        if (clearntp) {
 252                tk->ntp_error = 0;
 253                ntp_clear();
 254        }
 255        xt = tk_xtime(tk);
 256        update_vsyscall(&xt, &tk->wall_to_monotonic, tk->clock, tk->mult);
 257}
 258
 259/**
 260 * timekeeping_forward_now - update clock to the current time
 261 *
 262 * Forward the current clock to update its state since the last call to
 263 * update_wall_time(). This is useful before significant clock changes,
 264 * as it avoids having to deal with this time offset explicitly.
 265 */
 266static void timekeeping_forward_now(struct timekeeper *tk)
 267{
 268        cycle_t cycle_now, cycle_delta;
 269        struct clocksource *clock;
 270        s64 nsec;
 271
 272        clock = tk->clock;
 273        cycle_now = clock->read(clock);
 274        cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
 275        clock->cycle_last = cycle_now;
 276
 277        tk->xtime_nsec += cycle_delta * tk->mult;
 278
 279        /* If arch requires, add in gettimeoffset() */
 280        tk->xtime_nsec += (u64)arch_gettimeoffset() << tk->shift;
 281
 282        tk_normalize_xtime(tk);
 283
 284        nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
 285        timespec_add_ns(&tk->raw_time, nsec);
 286}
 287
 288/**
 289 * getnstimeofday - Returns the time of day in a timespec
 290 * @ts:         pointer to the timespec to be set
 291 *
 292 * Returns the time of day in a timespec.
 293 */
 294void getnstimeofday(struct timespec *ts)
 295{
 296        struct timekeeper *tk = &timekeeper;
 297        unsigned long seq;
 298        s64 nsecs = 0;
 299
 300        WARN_ON(timekeeping_suspended);
 301
 302        do {
 303                seq = read_seqbegin(&tk->lock);
 304
 305                ts->tv_sec = tk->xtime_sec;
 306                nsecs = timekeeping_get_ns(tk);
 307
 308        } while (read_seqretry(&tk->lock, seq));
 309
 310        ts->tv_nsec = 0;
 311        timespec_add_ns(ts, nsecs);
 312}
 313EXPORT_SYMBOL(getnstimeofday);
 314
 315ktime_t ktime_get(void)
 316{
 317        struct timekeeper *tk = &timekeeper;
 318        unsigned int seq;
 319        s64 secs, nsecs;
 320
 321        WARN_ON(timekeeping_suspended);
 322
 323        do {
 324                seq = read_seqbegin(&tk->lock);
 325                secs = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
 326                nsecs = timekeeping_get_ns(tk) + tk->wall_to_monotonic.tv_nsec;
 327
 328        } while (read_seqretry(&tk->lock, seq));
 329        /*
 330         * Use ktime_set/ktime_add_ns to create a proper ktime on
 331         * 32-bit architectures without CONFIG_KTIME_SCALAR.
 332         */
 333        return ktime_add_ns(ktime_set(secs, 0), nsecs);
 334}
 335EXPORT_SYMBOL_GPL(ktime_get);
 336
 337/**
 338 * ktime_get_ts - get the monotonic clock in timespec format
 339 * @ts:         pointer to timespec variable
 340 *
 341 * The function calculates the monotonic clock from the realtime
 342 * clock and the wall_to_monotonic offset and stores the result
 343 * in normalized timespec format in the variable pointed to by @ts.
 344 */
 345void ktime_get_ts(struct timespec *ts)
 346{
 347        struct timekeeper *tk = &timekeeper;
 348        struct timespec tomono;
 349        s64 nsec;
 350        unsigned int seq;
 351
 352        WARN_ON(timekeeping_suspended);
 353
 354        do {
 355                seq = read_seqbegin(&tk->lock);
 356                ts->tv_sec = tk->xtime_sec;
 357                nsec = timekeeping_get_ns(tk);
 358                tomono = tk->wall_to_monotonic;
 359
 360        } while (read_seqretry(&tk->lock, seq));
 361
 362        ts->tv_sec += tomono.tv_sec;
 363        ts->tv_nsec = 0;
 364        timespec_add_ns(ts, nsec + tomono.tv_nsec);
 365}
 366EXPORT_SYMBOL_GPL(ktime_get_ts);
 367
 368#ifdef CONFIG_NTP_PPS
 369
 370/**
 371 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
 372 * @ts_raw:     pointer to the timespec to be set to raw monotonic time
 373 * @ts_real:    pointer to the timespec to be set to the time of day
 374 *
 375 * This function reads both the time of day and raw monotonic time at the
 376 * same time atomically and stores the resulting timestamps in timespec
 377 * format.
 378 */
 379void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
 380{
 381        struct timekeeper *tk = &timekeeper;
 382        unsigned long seq;
 383        s64 nsecs_raw, nsecs_real;
 384
 385        WARN_ON_ONCE(timekeeping_suspended);
 386
 387        do {
 388                seq = read_seqbegin(&tk->lock);
 389
 390                *ts_raw = tk->raw_time;
 391                ts_real->tv_sec = tk->xtime_sec;
 392                ts_real->tv_nsec = 0;
 393
 394                nsecs_raw = timekeeping_get_ns_raw(tk);
 395                nsecs_real = timekeeping_get_ns(tk);
 396
 397        } while (read_seqretry(&tk->lock, seq));
 398
 399        timespec_add_ns(ts_raw, nsecs_raw);
 400        timespec_add_ns(ts_real, nsecs_real);
 401}
 402EXPORT_SYMBOL(getnstime_raw_and_real);
 403
 404#endif /* CONFIG_NTP_PPS */
 405
 406/**
 407 * do_gettimeofday - Returns the time of day in a timeval
 408 * @tv:         pointer to the timeval to be set
 409 *
 410 * NOTE: Users should be converted to using getnstimeofday()
 411 */
 412void do_gettimeofday(struct timeval *tv)
 413{
 414        struct timespec now;
 415
 416        getnstimeofday(&now);
 417        tv->tv_sec = now.tv_sec;
 418        tv->tv_usec = now.tv_nsec/1000;
 419}
 420EXPORT_SYMBOL(do_gettimeofday);
 421
 422/**
 423 * do_settimeofday - Sets the time of day
 424 * @tv:         pointer to the timespec variable containing the new time
 425 *
 426 * Sets the time of day to the new time and update NTP and notify hrtimers
 427 */
 428int do_settimeofday(const struct timespec *tv)
 429{
 430        struct timekeeper *tk = &timekeeper;
 431        struct timespec ts_delta, xt;
 432        unsigned long flags;
 433
 434        if (!timespec_valid_strict(tv))
 435                return -EINVAL;
 436
 437        write_seqlock_irqsave(&tk->lock, flags);
 438
 439        timekeeping_forward_now(tk);
 440
 441        xt = tk_xtime(tk);
 442        ts_delta.tv_sec = tv->tv_sec - xt.tv_sec;
 443        ts_delta.tv_nsec = tv->tv_nsec - xt.tv_nsec;
 444
 445        tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, ts_delta));
 446
 447        tk_set_xtime(tk, tv);
 448
 449        timekeeping_update(tk, true);
 450
 451        write_sequnlock_irqrestore(&tk->lock, flags);
 452
 453        /* signal hrtimers about time change */
 454        clock_was_set();
 455
 456        return 0;
 457}
 458EXPORT_SYMBOL(do_settimeofday);
 459
 460/**
 461 * timekeeping_inject_offset - Adds or subtracts from the current time.
 462 * @tv:         pointer to the timespec variable containing the offset
 463 *
 464 * Adds or subtracts an offset value from the current time.
 465 */
 466int timekeeping_inject_offset(struct timespec *ts)
 467{
 468        struct timekeeper *tk = &timekeeper;
 469        unsigned long flags;
 470        struct timespec tmp;
 471        int ret = 0;
 472
 473        if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
 474                return -EINVAL;
 475
 476        write_seqlock_irqsave(&tk->lock, flags);
 477
 478        timekeeping_forward_now(tk);
 479
 480        /* Make sure the proposed value is valid */
 481        tmp = timespec_add(tk_xtime(tk),  *ts);
 482        if (!timespec_valid_strict(&tmp)) {
 483                ret = -EINVAL;
 484                goto error;
 485        }
 486
 487        tk_xtime_add(tk, ts);
 488        tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *ts));
 489
 490error: /* even if we error out, we forwarded the time, so call update */
 491        timekeeping_update(tk, true);
 492
 493        write_sequnlock_irqrestore(&tk->lock, flags);
 494
 495        /* signal hrtimers about time change */
 496        clock_was_set();
 497
 498        return ret;
 499}
 500EXPORT_SYMBOL(timekeeping_inject_offset);
 501
 502/**
 503 * change_clocksource - Swaps clocksources if a new one is available
 504 *
 505 * Accumulates current time interval and initializes new clocksource
 506 */
 507static int change_clocksource(void *data)
 508{
 509        struct timekeeper *tk = &timekeeper;
 510        struct clocksource *new, *old;
 511        unsigned long flags;
 512
 513        new = (struct clocksource *) data;
 514
 515        write_seqlock_irqsave(&tk->lock, flags);
 516
 517        timekeeping_forward_now(tk);
 518        if (!new->enable || new->enable(new) == 0) {
 519                old = tk->clock;
 520                tk_setup_internals(tk, new);
 521                if (old->disable)
 522                        old->disable(old);
 523        }
 524        timekeeping_update(tk, true);
 525
 526        write_sequnlock_irqrestore(&tk->lock, flags);
 527
 528        return 0;
 529}
 530
 531/**
 532 * timekeeping_notify - Install a new clock source
 533 * @clock:              pointer to the clock source
 534 *
 535 * This function is called from clocksource.c after a new, better clock
 536 * source has been registered. The caller holds the clocksource_mutex.
 537 */
 538void timekeeping_notify(struct clocksource *clock)
 539{
 540        struct timekeeper *tk = &timekeeper;
 541
 542        if (tk->clock == clock)
 543                return;
 544        stop_machine(change_clocksource, clock, NULL);
 545        tick_clock_notify();
 546}
 547
 548/**
 549 * ktime_get_real - get the real (wall-) time in ktime_t format
 550 *
 551 * returns the time in ktime_t format
 552 */
 553ktime_t ktime_get_real(void)
 554{
 555        struct timespec now;
 556
 557        getnstimeofday(&now);
 558
 559        return timespec_to_ktime(now);
 560}
 561EXPORT_SYMBOL_GPL(ktime_get_real);
 562
 563/**
 564 * getrawmonotonic - Returns the raw monotonic time in a timespec
 565 * @ts:         pointer to the timespec to be set
 566 *
 567 * Returns the raw monotonic time (completely un-modified by ntp)
 568 */
 569void getrawmonotonic(struct timespec *ts)
 570{
 571        struct timekeeper *tk = &timekeeper;
 572        unsigned long seq;
 573        s64 nsecs;
 574
 575        do {
 576                seq = read_seqbegin(&tk->lock);
 577                nsecs = timekeeping_get_ns_raw(tk);
 578                *ts = tk->raw_time;
 579
 580        } while (read_seqretry(&tk->lock, seq));
 581
 582        timespec_add_ns(ts, nsecs);
 583}
 584EXPORT_SYMBOL(getrawmonotonic);
 585
 586/**
 587 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
 588 */
 589int timekeeping_valid_for_hres(void)
 590{
 591        struct timekeeper *tk = &timekeeper;
 592        unsigned long seq;
 593        int ret;
 594
 595        do {
 596                seq = read_seqbegin(&tk->lock);
 597
 598                ret = tk->clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
 599
 600        } while (read_seqretry(&tk->lock, seq));
 601
 602        return ret;
 603}
 604
 605/**
 606 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
 607 */
 608u64 timekeeping_max_deferment(void)
 609{
 610        struct timekeeper *tk = &timekeeper;
 611        unsigned long seq;
 612        u64 ret;
 613
 614        do {
 615                seq = read_seqbegin(&tk->lock);
 616
 617                ret = tk->clock->max_idle_ns;
 618
 619        } while (read_seqretry(&tk->lock, seq));
 620
 621        return ret;
 622}
 623
 624/**
 625 * read_persistent_clock -  Return time from the persistent clock.
 626 *
 627 * Weak dummy function for arches that do not yet support it.
 628 * Reads the time from the battery backed persistent clock.
 629 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
 630 *
 631 *  XXX - Do be sure to remove it once all arches implement it.
 632 */
 633void __attribute__((weak)) read_persistent_clock(struct timespec *ts)
 634{
 635        ts->tv_sec = 0;
 636        ts->tv_nsec = 0;
 637}
 638
 639/**
 640 * read_boot_clock -  Return time of the system start.
 641 *
 642 * Weak dummy function for arches that do not yet support it.
 643 * Function to read the exact time the system has been started.
 644 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
 645 *
 646 *  XXX - Do be sure to remove it once all arches implement it.
 647 */
 648void __attribute__((weak)) read_boot_clock(struct timespec *ts)
 649{
 650        ts->tv_sec = 0;
 651        ts->tv_nsec = 0;
 652}
 653
 654/*
 655 * timekeeping_init - Initializes the clocksource and common timekeeping values
 656 */
 657void __init timekeeping_init(void)
 658{
 659        struct timekeeper *tk = &timekeeper;
 660        struct clocksource *clock;
 661        unsigned long flags;
 662        struct timespec now, boot, tmp;
 663
 664        read_persistent_clock(&now);
 665        if (!timespec_valid_strict(&now)) {
 666                pr_warn("WARNING: Persistent clock returned invalid value!\n"
 667                        "         Check your CMOS/BIOS settings.\n");
 668                now.tv_sec = 0;
 669                now.tv_nsec = 0;
 670        }
 671
 672        read_boot_clock(&boot);
 673        if (!timespec_valid_strict(&boot)) {
 674                pr_warn("WARNING: Boot clock returned invalid value!\n"
 675                        "         Check your CMOS/BIOS settings.\n");
 676                boot.tv_sec = 0;
 677                boot.tv_nsec = 0;
 678        }
 679
 680        seqlock_init(&tk->lock);
 681
 682        ntp_init();
 683
 684        write_seqlock_irqsave(&tk->lock, flags);
 685        clock = clocksource_default_clock();
 686        if (clock->enable)
 687                clock->enable(clock);
 688        tk_setup_internals(tk, clock);
 689
 690        tk_set_xtime(tk, &now);
 691        tk->raw_time.tv_sec = 0;
 692        tk->raw_time.tv_nsec = 0;
 693        if (boot.tv_sec == 0 && boot.tv_nsec == 0)
 694                boot = tk_xtime(tk);
 695
 696        set_normalized_timespec(&tmp, -boot.tv_sec, -boot.tv_nsec);
 697        tk_set_wall_to_mono(tk, tmp);
 698
 699        tmp.tv_sec = 0;
 700        tmp.tv_nsec = 0;
 701        tk_set_sleep_time(tk, tmp);
 702
 703        write_sequnlock_irqrestore(&tk->lock, flags);
 704}
 705
 706/* time in seconds when suspend began */
 707static struct timespec timekeeping_suspend_time;
 708
 709/**
 710 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
 711 * @delta: pointer to a timespec delta value
 712 *
 713 * Takes a timespec offset measuring a suspend interval and properly
 714 * adds the sleep offset to the timekeeping variables.
 715 */
 716static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
 717                                                        struct timespec *delta)
 718{
 719        if (!timespec_valid_strict(delta)) {
 720                printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
 721                                        "sleep delta value!\n");
 722                return;
 723        }
 724        tk_xtime_add(tk, delta);
 725        tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *delta));
 726        tk_set_sleep_time(tk, timespec_add(tk->total_sleep_time, *delta));
 727}
 728
 729/**
 730 * timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values
 731 * @delta: pointer to a timespec delta value
 732 *
 733 * This hook is for architectures that cannot support read_persistent_clock
 734 * because their RTC/persistent clock is only accessible when irqs are enabled.
 735 *
 736 * This function should only be called by rtc_resume(), and allows
 737 * a suspend offset to be injected into the timekeeping values.
 738 */
 739void timekeeping_inject_sleeptime(struct timespec *delta)
 740{
 741        struct timekeeper *tk = &timekeeper;
 742        unsigned long flags;
 743        struct timespec ts;
 744
 745        /* Make sure we don't set the clock twice */
 746        read_persistent_clock(&ts);
 747        if (!(ts.tv_sec == 0 && ts.tv_nsec == 0))
 748                return;
 749
 750        write_seqlock_irqsave(&tk->lock, flags);
 751
 752        timekeeping_forward_now(tk);
 753
 754        __timekeeping_inject_sleeptime(tk, delta);
 755
 756        timekeeping_update(tk, true);
 757
 758        write_sequnlock_irqrestore(&tk->lock, flags);
 759
 760        /* signal hrtimers about time change */
 761        clock_was_set();
 762}
 763
 764/**
 765 * timekeeping_resume - Resumes the generic timekeeping subsystem.
 766 *
 767 * This is for the generic clocksource timekeeping.
 768 * xtime/wall_to_monotonic/jiffies/etc are
 769 * still managed by arch specific suspend/resume code.
 770 */
 771static void timekeeping_resume(void)
 772{
 773        struct timekeeper *tk = &timekeeper;
 774        unsigned long flags;
 775        struct timespec ts;
 776
 777        read_persistent_clock(&ts);
 778
 779        clocksource_resume();
 780
 781        write_seqlock_irqsave(&tk->lock, flags);
 782
 783        if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) {
 784                ts = timespec_sub(ts, timekeeping_suspend_time);
 785                __timekeeping_inject_sleeptime(tk, &ts);
 786        }
 787        /* re-base the last cycle value */
 788        tk->clock->cycle_last = tk->clock->read(tk->clock);
 789        tk->ntp_error = 0;
 790        timekeeping_suspended = 0;
 791        timekeeping_update(tk, false);
 792        write_sequnlock_irqrestore(&tk->lock, flags);
 793
 794        touch_softlockup_watchdog();
 795
 796        clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
 797
 798        /* Resume hrtimers */
 799        hrtimers_resume();
 800}
 801
 802static int timekeeping_suspend(void)
 803{
 804        struct timekeeper *tk = &timekeeper;
 805        unsigned long flags;
 806        struct timespec         delta, delta_delta;
 807        static struct timespec  old_delta;
 808
 809        read_persistent_clock(&timekeeping_suspend_time);
 810
 811        write_seqlock_irqsave(&tk->lock, flags);
 812        timekeeping_forward_now(tk);
 813        timekeeping_suspended = 1;
 814
 815        /*
 816         * To avoid drift caused by repeated suspend/resumes,
 817         * which each can add ~1 second drift error,
 818         * try to compensate so the difference in system time
 819         * and persistent_clock time stays close to constant.
 820         */
 821        delta = timespec_sub(tk_xtime(tk), timekeeping_suspend_time);
 822        delta_delta = timespec_sub(delta, old_delta);
 823        if (abs(delta_delta.tv_sec)  >= 2) {
 824                /*
 825                 * if delta_delta is too large, assume time correction
 826                 * has occured and set old_delta to the current delta.
 827                 */
 828                old_delta = delta;
 829        } else {
 830                /* Otherwise try to adjust old_system to compensate */
 831                timekeeping_suspend_time =
 832                        timespec_add(timekeeping_suspend_time, delta_delta);
 833        }
 834        write_sequnlock_irqrestore(&tk->lock, flags);
 835
 836        clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
 837        clocksource_suspend();
 838
 839        return 0;
 840}
 841
 842/* sysfs resume/suspend bits for timekeeping */
 843static struct syscore_ops timekeeping_syscore_ops = {
 844        .resume         = timekeeping_resume,
 845        .suspend        = timekeeping_suspend,
 846};
 847
 848static int __init timekeeping_init_ops(void)
 849{
 850        register_syscore_ops(&timekeeping_syscore_ops);
 851        return 0;
 852}
 853
 854device_initcall(timekeeping_init_ops);
 855
 856/*
 857 * If the error is already larger, we look ahead even further
 858 * to compensate for late or lost adjustments.
 859 */
 860static __always_inline int timekeeping_bigadjust(struct timekeeper *tk,
 861                                                 s64 error, s64 *interval,
 862                                                 s64 *offset)
 863{
 864        s64 tick_error, i;
 865        u32 look_ahead, adj;
 866        s32 error2, mult;
 867
 868        /*
 869         * Use the current error value to determine how much to look ahead.
 870         * The larger the error the slower we adjust for it to avoid problems
 871         * with losing too many ticks, otherwise we would overadjust and
 872         * produce an even larger error.  The smaller the adjustment the
 873         * faster we try to adjust for it, as lost ticks can do less harm
 874         * here.  This is tuned so that an error of about 1 msec is adjusted
 875         * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
 876         */
 877        error2 = tk->ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
 878        error2 = abs(error2);
 879        for (look_ahead = 0; error2 > 0; look_ahead++)
 880                error2 >>= 2;
 881
 882        /*
 883         * Now calculate the error in (1 << look_ahead) ticks, but first
 884         * remove the single look ahead already included in the error.
 885         */
 886        tick_error = ntp_tick_length() >> (tk->ntp_error_shift + 1);
 887        tick_error -= tk->xtime_interval >> 1;
 888        error = ((error - tick_error) >> look_ahead) + tick_error;
 889
 890        /* Finally calculate the adjustment shift value.  */
 891        i = *interval;
 892        mult = 1;
 893        if (error < 0) {
 894                error = -error;
 895                *interval = -*interval;
 896                *offset = -*offset;
 897                mult = -1;
 898        }
 899        for (adj = 0; error > i; adj++)
 900                error >>= 1;
 901
 902        *interval <<= adj;
 903        *offset <<= adj;
 904        return mult << adj;
 905}
 906
 907/*
 908 * Adjust the multiplier to reduce the error value,
 909 * this is optimized for the most common adjustments of -1,0,1,
 910 * for other values we can do a bit more work.
 911 */
 912static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
 913{
 914        s64 error, interval = tk->cycle_interval;
 915        int adj;
 916
 917        /*
 918         * The point of this is to check if the error is greater than half
 919         * an interval.
 920         *
 921         * First we shift it down from NTP_SHIFT to clocksource->shifted nsecs.
 922         *
 923         * Note we subtract one in the shift, so that error is really error*2.
 924         * This "saves" dividing(shifting) interval twice, but keeps the
 925         * (error > interval) comparison as still measuring if error is
 926         * larger than half an interval.
 927         *
 928         * Note: It does not "save" on aggravation when reading the code.
 929         */
 930        error = tk->ntp_error >> (tk->ntp_error_shift - 1);
 931        if (error > interval) {
 932                /*
 933                 * We now divide error by 4(via shift), which checks if
 934                 * the error is greater than twice the interval.
 935                 * If it is greater, we need a bigadjust, if its smaller,
 936                 * we can adjust by 1.
 937                 */
 938                error >>= 2;
 939                /*
 940                 * XXX - In update_wall_time, we round up to the next
 941                 * nanosecond, and store the amount rounded up into
 942                 * the error. This causes the likely below to be unlikely.
 943                 *
 944                 * The proper fix is to avoid rounding up by using
 945                 * the high precision tk->xtime_nsec instead of
 946                 * xtime.tv_nsec everywhere. Fixing this will take some
 947                 * time.
 948                 */
 949                if (likely(error <= interval))
 950                        adj = 1;
 951                else
 952                        adj = timekeeping_bigadjust(tk, error, &interval, &offset);
 953        } else {
 954                if (error < -interval) {
 955                        /* See comment above, this is just switched for the negative */
 956                        error >>= 2;
 957                        if (likely(error >= -interval)) {
 958                                adj = -1;
 959                                interval = -interval;
 960                                offset = -offset;
 961                        } else {
 962                                adj = timekeeping_bigadjust(tk, error, &interval, &offset);
 963                        }
 964                } else {
 965                        goto out_adjust;
 966                }
 967        }
 968
 969        if (unlikely(tk->clock->maxadj &&
 970                (tk->mult + adj > tk->clock->mult + tk->clock->maxadj))) {
 971                printk_once(KERN_WARNING
 972                        "Adjusting %s more than 11%% (%ld vs %ld)\n",
 973                        tk->clock->name, (long)tk->mult + adj,
 974                        (long)tk->clock->mult + tk->clock->maxadj);
 975        }
 976        /*
 977         * So the following can be confusing.
 978         *
 979         * To keep things simple, lets assume adj == 1 for now.
 980         *
 981         * When adj != 1, remember that the interval and offset values
 982         * have been appropriately scaled so the math is the same.
 983         *
 984         * The basic idea here is that we're increasing the multiplier
 985         * by one, this causes the xtime_interval to be incremented by
 986         * one cycle_interval. This is because:
 987         *      xtime_interval = cycle_interval * mult
 988         * So if mult is being incremented by one:
 989         *      xtime_interval = cycle_interval * (mult + 1)
 990         * Its the same as:
 991         *      xtime_interval = (cycle_interval * mult) + cycle_interval
 992         * Which can be shortened to:
 993         *      xtime_interval += cycle_interval
 994         *
 995         * So offset stores the non-accumulated cycles. Thus the current
 996         * time (in shifted nanoseconds) is:
 997         *      now = (offset * adj) + xtime_nsec
 998         * Now, even though we're adjusting the clock frequency, we have
 999         * to keep time consistent. In other words, we can't jump back
1000         * in time, and we also want to avoid jumping forward in time.
1001         *
1002         * So given the same offset value, we need the time to be the same
1003         * both before and after the freq adjustment.
1004         *      now = (offset * adj_1) + xtime_nsec_1
1005         *      now = (offset * adj_2) + xtime_nsec_2
1006         * So:
1007         *      (offset * adj_1) + xtime_nsec_1 =
1008         *              (offset * adj_2) + xtime_nsec_2
1009         * And we know:
1010         *      adj_2 = adj_1 + 1
1011         * So:
1012         *      (offset * adj_1) + xtime_nsec_1 =
1013         *              (offset * (adj_1+1)) + xtime_nsec_2
1014         *      (offset * adj_1) + xtime_nsec_1 =
1015         *              (offset * adj_1) + offset + xtime_nsec_2
1016         * Canceling the sides:
1017         *      xtime_nsec_1 = offset + xtime_nsec_2
1018         * Which gives us:
1019         *      xtime_nsec_2 = xtime_nsec_1 - offset
1020         * Which simplfies to:
1021         *      xtime_nsec -= offset
1022         *
1023         * XXX - TODO: Doc ntp_error calculation.
1024         */
1025        tk->mult += adj;
1026        tk->xtime_interval += interval;
1027        tk->xtime_nsec -= offset;
1028        tk->ntp_error -= (interval - offset) << tk->ntp_error_shift;
1029
1030out_adjust:
1031        /*
1032         * It may be possible that when we entered this function, xtime_nsec
1033         * was very small.  Further, if we're slightly speeding the clocksource
1034         * in the code above, its possible the required corrective factor to
1035         * xtime_nsec could cause it to underflow.
1036         *
1037         * Now, since we already accumulated the second, cannot simply roll
1038         * the accumulated second back, since the NTP subsystem has been
1039         * notified via second_overflow. So instead we push xtime_nsec forward
1040         * by the amount we underflowed, and add that amount into the error.
1041         *
1042         * We'll correct this error next time through this function, when
1043         * xtime_nsec is not as small.
1044         */
1045        if (unlikely((s64)tk->xtime_nsec < 0)) {
1046                s64 neg = -(s64)tk->xtime_nsec;
1047                tk->xtime_nsec = 0;
1048                tk->ntp_error += neg << tk->ntp_error_shift;
1049        }
1050
1051}
1052
1053/**
1054 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1055 *
1056 * Helper function that accumulates a the nsecs greater then a second
1057 * from the xtime_nsec field to the xtime_secs field.
1058 * It also calls into the NTP code to handle leapsecond processing.
1059 *
1060 */
1061static inline void accumulate_nsecs_to_secs(struct timekeeper *tk)
1062{
1063        u64 nsecps = (u64)NSEC_PER_SEC << tk->shift;
1064
1065        while (tk->xtime_nsec >= nsecps) {
1066                int leap;
1067
1068                tk->xtime_nsec -= nsecps;
1069                tk->xtime_sec++;
1070
1071                /* Figure out if its a leap sec and apply if needed */
1072                leap = second_overflow(tk->xtime_sec);
1073                if (unlikely(leap)) {
1074                        struct timespec ts;
1075
1076                        tk->xtime_sec += leap;
1077
1078                        ts.tv_sec = leap;
1079                        ts.tv_nsec = 0;
1080                        tk_set_wall_to_mono(tk,
1081                                timespec_sub(tk->wall_to_monotonic, ts));
1082
1083                        clock_was_set_delayed();
1084                }
1085        }
1086}
1087
1088/**
1089 * logarithmic_accumulation - shifted accumulation of cycles
1090 *
1091 * This functions accumulates a shifted interval of cycles into
1092 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1093 * loop.
1094 *
1095 * Returns the unconsumed cycles.
1096 */
1097static cycle_t logarithmic_accumulation(struct timekeeper *tk, cycle_t offset,
1098                                                u32 shift)
1099{
1100        u64 raw_nsecs;
1101
1102        /* If the offset is smaller then a shifted interval, do nothing */
1103        if (offset < tk->cycle_interval<<shift)
1104                return offset;
1105
1106        /* Accumulate one shifted interval */
1107        offset -= tk->cycle_interval << shift;
1108        tk->clock->cycle_last += tk->cycle_interval << shift;
1109
1110        tk->xtime_nsec += tk->xtime_interval << shift;
1111        accumulate_nsecs_to_secs(tk);
1112
1113        /* Accumulate raw time */
1114        raw_nsecs = tk->raw_interval << shift;
1115        raw_nsecs += tk->raw_time.tv_nsec;
1116        if (raw_nsecs >= NSEC_PER_SEC) {
1117                u64 raw_secs = raw_nsecs;
1118                raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
1119                tk->raw_time.tv_sec += raw_secs;
1120        }
1121        tk->raw_time.tv_nsec = raw_nsecs;
1122
1123        /* Accumulate error between NTP and clock interval */
1124        tk->ntp_error += ntp_tick_length() << shift;
1125        tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
1126                                                (tk->ntp_error_shift + shift);
1127
1128        return offset;
1129}
1130
1131/**
1132 * update_wall_time - Uses the current clocksource to increment the wall time
1133 *
1134 */
1135static void update_wall_time(void)
1136{
1137        struct clocksource *clock;
1138        struct timekeeper *tk = &timekeeper;
1139        cycle_t offset;
1140        int shift = 0, maxshift;
1141        unsigned long flags;
1142        s64 remainder;
1143
1144        write_seqlock_irqsave(&tk->lock, flags);
1145
1146        /* Make sure we're fully resumed: */
1147        if (unlikely(timekeeping_suspended))
1148                goto out;
1149
1150        clock = tk->clock;
1151
1152#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1153        offset = tk->cycle_interval;
1154#else
1155        offset = (clock->read(clock) - clock->cycle_last) & clock->mask;
1156#endif
1157
1158        /* Check if there's really nothing to do */
1159        if (offset < tk->cycle_interval)
1160                goto out;
1161
1162        /*
1163         * With NO_HZ we may have to accumulate many cycle_intervals
1164         * (think "ticks") worth of time at once. To do this efficiently,
1165         * we calculate the largest doubling multiple of cycle_intervals
1166         * that is smaller than the offset.  We then accumulate that
1167         * chunk in one go, and then try to consume the next smaller
1168         * doubled multiple.
1169         */
1170        shift = ilog2(offset) - ilog2(tk->cycle_interval);
1171        shift = max(0, shift);
1172        /* Bound shift to one less than what overflows tick_length */
1173        maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
1174        shift = min(shift, maxshift);
1175        while (offset >= tk->cycle_interval) {
1176                offset = logarithmic_accumulation(tk, offset, shift);
1177                if (offset < tk->cycle_interval<<shift)
1178                        shift--;
1179        }
1180
1181        /* correct the clock when NTP error is too big */
1182        timekeeping_adjust(tk, offset);
1183
1184
1185        /*
1186        * Store only full nanoseconds into xtime_nsec after rounding
1187        * it up and add the remainder to the error difference.
1188        * XXX - This is necessary to avoid small 1ns inconsistnecies caused
1189        * by truncating the remainder in vsyscalls. However, it causes
1190        * additional work to be done in timekeeping_adjust(). Once
1191        * the vsyscall implementations are converted to use xtime_nsec
1192        * (shifted nanoseconds), this can be killed.
1193        */
1194        remainder = tk->xtime_nsec & ((1ULL << tk->shift) - 1);
1195        tk->xtime_nsec -= remainder;
1196        tk->xtime_nsec += 1ULL << tk->shift;
1197        tk->ntp_error += remainder << tk->ntp_error_shift;
1198
1199        /*
1200         * Finally, make sure that after the rounding
1201         * xtime_nsec isn't larger than NSEC_PER_SEC
1202         */
1203        accumulate_nsecs_to_secs(tk);
1204
1205        timekeeping_update(tk, false);
1206
1207out:
1208        write_sequnlock_irqrestore(&tk->lock, flags);
1209
1210}
1211
1212/**
1213 * getboottime - Return the real time of system boot.
1214 * @ts:         pointer to the timespec to be set
1215 *
1216 * Returns the wall-time of boot in a timespec.
1217 *
1218 * This is based on the wall_to_monotonic offset and the total suspend
1219 * time. Calls to settimeofday will affect the value returned (which
1220 * basically means that however wrong your real time clock is at boot time,
1221 * you get the right time here).
1222 */
1223void getboottime(struct timespec *ts)
1224{
1225        struct timekeeper *tk = &timekeeper;
1226        struct timespec boottime = {
1227                .tv_sec = tk->wall_to_monotonic.tv_sec +
1228                                tk->total_sleep_time.tv_sec,
1229                .tv_nsec = tk->wall_to_monotonic.tv_nsec +
1230                                tk->total_sleep_time.tv_nsec
1231        };
1232
1233        set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec);
1234}
1235EXPORT_SYMBOL_GPL(getboottime);
1236
1237/**
1238 * get_monotonic_boottime - Returns monotonic time since boot
1239 * @ts:         pointer to the timespec to be set
1240 *
1241 * Returns the monotonic time since boot in a timespec.
1242 *
1243 * This is similar to CLOCK_MONTONIC/ktime_get_ts, but also
1244 * includes the time spent in suspend.
1245 */
1246void get_monotonic_boottime(struct timespec *ts)
1247{
1248        struct timekeeper *tk = &timekeeper;
1249        struct timespec tomono, sleep;
1250        s64 nsec;
1251        unsigned int seq;
1252
1253        WARN_ON(timekeeping_suspended);
1254
1255        do {
1256                seq = read_seqbegin(&tk->lock);
1257                ts->tv_sec = tk->xtime_sec;
1258                nsec = timekeeping_get_ns(tk);
1259                tomono = tk->wall_to_monotonic;
1260                sleep = tk->total_sleep_time;
1261
1262        } while (read_seqretry(&tk->lock, seq));
1263
1264        ts->tv_sec += tomono.tv_sec + sleep.tv_sec;
1265        ts->tv_nsec = 0;
1266        timespec_add_ns(ts, nsec + tomono.tv_nsec + sleep.tv_nsec);
1267}
1268EXPORT_SYMBOL_GPL(get_monotonic_boottime);
1269
1270/**
1271 * ktime_get_boottime - Returns monotonic time since boot in a ktime
1272 *
1273 * Returns the monotonic time since boot in a ktime
1274 *
1275 * This is similar to CLOCK_MONTONIC/ktime_get, but also
1276 * includes the time spent in suspend.
1277 */
1278ktime_t ktime_get_boottime(void)
1279{
1280        struct timespec ts;
1281
1282        get_monotonic_boottime(&ts);
1283        return timespec_to_ktime(ts);
1284}
1285EXPORT_SYMBOL_GPL(ktime_get_boottime);
1286
1287/**
1288 * monotonic_to_bootbased - Convert the monotonic time to boot based.
1289 * @ts:         pointer to the timespec to be converted
1290 */
1291void monotonic_to_bootbased(struct timespec *ts)
1292{
1293        struct timekeeper *tk = &timekeeper;
1294
1295        *ts = timespec_add(*ts, tk->total_sleep_time);
1296}
1297EXPORT_SYMBOL_GPL(monotonic_to_bootbased);
1298
1299unsigned long get_seconds(void)
1300{
1301        struct timekeeper *tk = &timekeeper;
1302
1303        return tk->xtime_sec;
1304}
1305EXPORT_SYMBOL(get_seconds);
1306
1307struct timespec __current_kernel_time(void)
1308{
1309        struct timekeeper *tk = &timekeeper;
1310
1311        return tk_xtime(tk);
1312}
1313
1314struct timespec current_kernel_time(void)
1315{
1316        struct timekeeper *tk = &timekeeper;
1317        struct timespec now;
1318        unsigned long seq;
1319
1320        do {
1321                seq = read_seqbegin(&tk->lock);
1322
1323                now = tk_xtime(tk);
1324        } while (read_seqretry(&tk->lock, seq));
1325
1326        return now;
1327}
1328EXPORT_SYMBOL(current_kernel_time);
1329
1330struct timespec get_monotonic_coarse(void)
1331{
1332        struct timekeeper *tk = &timekeeper;
1333        struct timespec now, mono;
1334        unsigned long seq;
1335
1336        do {
1337                seq = read_seqbegin(&tk->lock);
1338
1339                now = tk_xtime(tk);
1340                mono = tk->wall_to_monotonic;
1341        } while (read_seqretry(&tk->lock, seq));
1342
1343        set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
1344                                now.tv_nsec + mono.tv_nsec);
1345        return now;
1346}
1347
1348/*
1349 * The 64-bit jiffies value is not atomic - you MUST NOT read it
1350 * without sampling the sequence number in xtime_lock.
1351 * jiffies is defined in the linker script...
1352 */
1353void do_timer(unsigned long ticks)
1354{
1355        jiffies_64 += ticks;
1356        update_wall_time();
1357        calc_global_load(ticks);
1358}
1359
1360/**
1361 * get_xtime_and_monotonic_and_sleep_offset() - get xtime, wall_to_monotonic,
1362 *    and sleep offsets.
1363 * @xtim:       pointer to timespec to be set with xtime
1364 * @wtom:       pointer to timespec to be set with wall_to_monotonic
1365 * @sleep:      pointer to timespec to be set with time in suspend
1366 */
1367void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
1368                                struct timespec *wtom, struct timespec *sleep)
1369{
1370        struct timekeeper *tk = &timekeeper;
1371        unsigned long seq;
1372
1373        do {
1374                seq = read_seqbegin(&tk->lock);
1375                *xtim = tk_xtime(tk);
1376                *wtom = tk->wall_to_monotonic;
1377                *sleep = tk->total_sleep_time;
1378        } while (read_seqretry(&tk->lock, seq));
1379}
1380
1381#ifdef CONFIG_HIGH_RES_TIMERS
1382/**
1383 * ktime_get_update_offsets - hrtimer helper
1384 * @offs_real:  pointer to storage for monotonic -> realtime offset
1385 * @offs_boot:  pointer to storage for monotonic -> boottime offset
1386 *
1387 * Returns current monotonic time and updates the offsets
1388 * Called from hrtimer_interupt() or retrigger_next_event()
1389 */
1390ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot)
1391{
1392        struct timekeeper *tk = &timekeeper;
1393        ktime_t now;
1394        unsigned int seq;
1395        u64 secs, nsecs;
1396
1397        do {
1398                seq = read_seqbegin(&tk->lock);
1399
1400                secs = tk->xtime_sec;
1401                nsecs = timekeeping_get_ns(tk);
1402
1403                *offs_real = tk->offs_real;
1404                *offs_boot = tk->offs_boot;
1405        } while (read_seqretry(&tk->lock, seq));
1406
1407        now = ktime_add_ns(ktime_set(secs, 0), nsecs);
1408        now = ktime_sub(now, *offs_real);
1409        return now;
1410}
1411#endif
1412
1413/**
1414 * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
1415 */
1416ktime_t ktime_get_monotonic_offset(void)
1417{
1418        struct timekeeper *tk = &timekeeper;
1419        unsigned long seq;
1420        struct timespec wtom;
1421
1422        do {
1423                seq = read_seqbegin(&tk->lock);
1424                wtom = tk->wall_to_monotonic;
1425        } while (read_seqretry(&tk->lock, seq));
1426
1427        return timespec_to_ktime(wtom);
1428}
1429EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset);
1430
1431/**
1432 * xtime_update() - advances the timekeeping infrastructure
1433 * @ticks:      number of ticks, that have elapsed since the last call.
1434 *
1435 * Must be called with interrupts disabled.
1436 */
1437void xtime_update(unsigned long ticks)
1438{
1439        write_seqlock(&xtime_lock);
1440        do_timer(ticks);
1441        write_sequnlock(&xtime_lock);
1442}
1443
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