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