Commit | Line | Data |
---|---|---|
8524070b | 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/sysdev.h> | |
17 | #include <linux/clocksource.h> | |
18 | #include <linux/jiffies.h> | |
19 | #include <linux/time.h> | |
20 | #include <linux/tick.h> | |
21 | ||
22 | ||
23 | /* | |
24 | * This read-write spinlock protects us from races in SMP while | |
dce48a84 | 25 | * playing with xtime. |
8524070b | 26 | */ |
ba2a631b | 27 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock); |
8524070b | 28 | |
29 | ||
30 | /* | |
31 | * The current time | |
32 | * wall_to_monotonic is what we need to add to xtime (or xtime corrected | |
33 | * for sub jiffie times) to get to monotonic time. Monotonic is pegged | |
34 | * at zero at system boot time, so wall_to_monotonic will be negative, | |
35 | * however, we will ALWAYS keep the tv_nsec part positive so we can use | |
36 | * the usual normalization. | |
7c3f1a57 TJ |
37 | * |
38 | * wall_to_monotonic is moved after resume from suspend for the monotonic | |
39 | * time not to jump. We need to add total_sleep_time to wall_to_monotonic | |
40 | * to get the real boot based time offset. | |
41 | * | |
42 | * - wall_to_monotonic is no longer the boot time, getboottime must be | |
43 | * used instead. | |
8524070b | 44 | */ |
45 | struct timespec xtime __attribute__ ((aligned (16))); | |
46 | struct timespec wall_to_monotonic __attribute__ ((aligned (16))); | |
7c3f1a57 | 47 | static unsigned long total_sleep_time; /* seconds */ |
8524070b | 48 | |
1c5745aa TG |
49 | /* flag for if timekeeping is suspended */ |
50 | int __read_mostly timekeeping_suspended; | |
51 | ||
17c38b74 | 52 | static struct timespec xtime_cache __attribute__ ((aligned (16))); |
1001d0a9 | 53 | void update_xtime_cache(u64 nsec) |
17c38b74 | 54 | { |
55 | xtime_cache = xtime; | |
56 | timespec_add_ns(&xtime_cache, nsec); | |
57 | } | |
17c38b74 | 58 | |
7dffa3c6 | 59 | struct clocksource *clock; |
8524070b | 60 | |
31089c13 JS |
61 | /* must hold xtime_lock */ |
62 | void timekeeping_leap_insert(int leapsecond) | |
63 | { | |
64 | xtime.tv_sec += leapsecond; | |
65 | wall_to_monotonic.tv_sec -= leapsecond; | |
66 | update_vsyscall(&xtime, clock); | |
67 | } | |
8524070b | 68 | |
69 | #ifdef CONFIG_GENERIC_TIME | |
70 | /** | |
9a055117 | 71 | * clocksource_forward_now - update clock to the current time |
8524070b | 72 | * |
9a055117 RZ |
73 | * Forward the current clock to update its state since the last call to |
74 | * update_wall_time(). This is useful before significant clock changes, | |
75 | * as it avoids having to deal with this time offset explicitly. | |
8524070b | 76 | */ |
9a055117 | 77 | static void clocksource_forward_now(void) |
8524070b | 78 | { |
79 | cycle_t cycle_now, cycle_delta; | |
9a055117 | 80 | s64 nsec; |
8524070b | 81 | |
8524070b | 82 | cycle_now = clocksource_read(clock); |
8524070b | 83 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; |
9a055117 | 84 | clock->cycle_last = cycle_now; |
8524070b | 85 | |
9a055117 | 86 | nsec = cyc2ns(clock, cycle_delta); |
7d27558c | 87 | |
88 | /* If arch requires, add in gettimeoffset() */ | |
89 | nsec += arch_gettimeoffset(); | |
90 | ||
9a055117 | 91 | timespec_add_ns(&xtime, nsec); |
2d42244a JS |
92 | |
93 | nsec = ((s64)cycle_delta * clock->mult_orig) >> clock->shift; | |
94 | clock->raw_time.tv_nsec += nsec; | |
8524070b | 95 | } |
96 | ||
97 | /** | |
efd9ac86 | 98 | * getnstimeofday - Returns the time of day in a timespec |
8524070b | 99 | * @ts: pointer to the timespec to be set |
100 | * | |
efd9ac86 | 101 | * Returns the time of day in a timespec. |
8524070b | 102 | */ |
efd9ac86 | 103 | void getnstimeofday(struct timespec *ts) |
8524070b | 104 | { |
9a055117 | 105 | cycle_t cycle_now, cycle_delta; |
8524070b | 106 | unsigned long seq; |
107 | s64 nsecs; | |
108 | ||
1c5745aa TG |
109 | WARN_ON(timekeeping_suspended); |
110 | ||
8524070b | 111 | do { |
112 | seq = read_seqbegin(&xtime_lock); | |
113 | ||
114 | *ts = xtime; | |
9a055117 RZ |
115 | |
116 | /* read clocksource: */ | |
117 | cycle_now = clocksource_read(clock); | |
118 | ||
119 | /* calculate the delta since the last update_wall_time: */ | |
120 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; | |
121 | ||
122 | /* convert to nanoseconds: */ | |
123 | nsecs = cyc2ns(clock, cycle_delta); | |
8524070b | 124 | |
7d27558c | 125 | /* If arch requires, add in gettimeoffset() */ |
126 | nsecs += arch_gettimeoffset(); | |
127 | ||
8524070b | 128 | } while (read_seqretry(&xtime_lock, seq)); |
129 | ||
130 | timespec_add_ns(ts, nsecs); | |
131 | } | |
132 | ||
8524070b | 133 | EXPORT_SYMBOL(getnstimeofday); |
134 | ||
951ed4d3 MS |
135 | ktime_t ktime_get(void) |
136 | { | |
137 | cycle_t cycle_now, cycle_delta; | |
138 | unsigned int seq; | |
139 | s64 secs, nsecs; | |
140 | ||
141 | WARN_ON(timekeeping_suspended); | |
142 | ||
143 | do { | |
144 | seq = read_seqbegin(&xtime_lock); | |
145 | secs = xtime.tv_sec + wall_to_monotonic.tv_sec; | |
146 | nsecs = xtime.tv_nsec + wall_to_monotonic.tv_nsec; | |
147 | ||
148 | /* read clocksource: */ | |
149 | cycle_now = clocksource_read(clock); | |
150 | ||
151 | /* calculate the delta since the last update_wall_time: */ | |
152 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; | |
153 | ||
154 | /* convert to nanoseconds: */ | |
155 | nsecs += cyc2ns(clock, cycle_delta); | |
156 | ||
157 | } while (read_seqretry(&xtime_lock, seq)); | |
158 | /* | |
159 | * Use ktime_set/ktime_add_ns to create a proper ktime on | |
160 | * 32-bit architectures without CONFIG_KTIME_SCALAR. | |
161 | */ | |
162 | return ktime_add_ns(ktime_set(secs, 0), nsecs); | |
163 | } | |
164 | EXPORT_SYMBOL_GPL(ktime_get); | |
165 | ||
166 | /** | |
167 | * ktime_get_ts - get the monotonic clock in timespec format | |
168 | * @ts: pointer to timespec variable | |
169 | * | |
170 | * The function calculates the monotonic clock from the realtime | |
171 | * clock and the wall_to_monotonic offset and stores the result | |
172 | * in normalized timespec format in the variable pointed to by @ts. | |
173 | */ | |
174 | void ktime_get_ts(struct timespec *ts) | |
175 | { | |
176 | cycle_t cycle_now, cycle_delta; | |
177 | struct timespec tomono; | |
178 | unsigned int seq; | |
179 | s64 nsecs; | |
180 | ||
181 | WARN_ON(timekeeping_suspended); | |
182 | ||
183 | do { | |
184 | seq = read_seqbegin(&xtime_lock); | |
185 | *ts = xtime; | |
186 | tomono = wall_to_monotonic; | |
187 | ||
188 | /* read clocksource: */ | |
189 | cycle_now = clocksource_read(clock); | |
190 | ||
191 | /* calculate the delta since the last update_wall_time: */ | |
192 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; | |
193 | ||
194 | /* convert to nanoseconds: */ | |
195 | nsecs = cyc2ns(clock, cycle_delta); | |
196 | ||
197 | } while (read_seqretry(&xtime_lock, seq)); | |
198 | ||
199 | set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec, | |
200 | ts->tv_nsec + tomono.tv_nsec + nsecs); | |
201 | } | |
202 | EXPORT_SYMBOL_GPL(ktime_get_ts); | |
203 | ||
8524070b | 204 | /** |
205 | * do_gettimeofday - Returns the time of day in a timeval | |
206 | * @tv: pointer to the timeval to be set | |
207 | * | |
efd9ac86 | 208 | * NOTE: Users should be converted to using getnstimeofday() |
8524070b | 209 | */ |
210 | void do_gettimeofday(struct timeval *tv) | |
211 | { | |
212 | struct timespec now; | |
213 | ||
efd9ac86 | 214 | getnstimeofday(&now); |
8524070b | 215 | tv->tv_sec = now.tv_sec; |
216 | tv->tv_usec = now.tv_nsec/1000; | |
217 | } | |
218 | ||
219 | EXPORT_SYMBOL(do_gettimeofday); | |
220 | /** | |
221 | * do_settimeofday - Sets the time of day | |
222 | * @tv: pointer to the timespec variable containing the new time | |
223 | * | |
224 | * Sets the time of day to the new time and update NTP and notify hrtimers | |
225 | */ | |
226 | int do_settimeofday(struct timespec *tv) | |
227 | { | |
9a055117 | 228 | struct timespec ts_delta; |
8524070b | 229 | unsigned long flags; |
8524070b | 230 | |
231 | if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) | |
232 | return -EINVAL; | |
233 | ||
234 | write_seqlock_irqsave(&xtime_lock, flags); | |
235 | ||
9a055117 RZ |
236 | clocksource_forward_now(); |
237 | ||
238 | ts_delta.tv_sec = tv->tv_sec - xtime.tv_sec; | |
239 | ts_delta.tv_nsec = tv->tv_nsec - xtime.tv_nsec; | |
240 | wall_to_monotonic = timespec_sub(wall_to_monotonic, ts_delta); | |
8524070b | 241 | |
9a055117 | 242 | xtime = *tv; |
8524070b | 243 | |
1001d0a9 | 244 | update_xtime_cache(0); |
8524070b | 245 | |
246 | clock->error = 0; | |
247 | ntp_clear(); | |
248 | ||
249 | update_vsyscall(&xtime, clock); | |
250 | ||
251 | write_sequnlock_irqrestore(&xtime_lock, flags); | |
252 | ||
253 | /* signal hrtimers about time change */ | |
254 | clock_was_set(); | |
255 | ||
256 | return 0; | |
257 | } | |
258 | ||
259 | EXPORT_SYMBOL(do_settimeofday); | |
260 | ||
261 | /** | |
262 | * change_clocksource - Swaps clocksources if a new one is available | |
263 | * | |
264 | * Accumulates current time interval and initializes new clocksource | |
265 | */ | |
266 | static void change_clocksource(void) | |
267 | { | |
4614e6ad | 268 | struct clocksource *new, *old; |
8524070b | 269 | |
270 | new = clocksource_get_next(); | |
271 | ||
272 | if (clock == new) | |
273 | return; | |
274 | ||
9a055117 | 275 | clocksource_forward_now(); |
8524070b | 276 | |
4614e6ad MD |
277 | if (clocksource_enable(new)) |
278 | return; | |
2d42244a | 279 | |
4614e6ad MD |
280 | new->raw_time = clock->raw_time; |
281 | old = clock; | |
8524070b | 282 | clock = new; |
4614e6ad MD |
283 | clocksource_disable(old); |
284 | ||
9a055117 | 285 | clock->cycle_last = 0; |
4614e6ad | 286 | clock->cycle_last = clocksource_read(clock); |
8524070b | 287 | clock->error = 0; |
288 | clock->xtime_nsec = 0; | |
10a398d0 | 289 | clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH); |
8524070b | 290 | |
291 | tick_clock_notify(); | |
292 | ||
92896bd9 LT |
293 | /* |
294 | * We're holding xtime lock and waking up klogd would deadlock | |
295 | * us on enqueue. So no printing! | |
8524070b | 296 | printk(KERN_INFO "Time: %s clocksource has been installed.\n", |
297 | clock->name); | |
92896bd9 | 298 | */ |
8524070b | 299 | } |
a40f262c | 300 | #else /* GENERIC_TIME */ |
9a055117 | 301 | static inline void clocksource_forward_now(void) { } |
8524070b | 302 | static inline void change_clocksource(void) { } |
a40f262c TG |
303 | |
304 | /** | |
305 | * ktime_get - get the monotonic time in ktime_t format | |
306 | * | |
307 | * returns the time in ktime_t format | |
308 | */ | |
309 | ktime_t ktime_get(void) | |
310 | { | |
311 | struct timespec now; | |
312 | ||
313 | ktime_get_ts(&now); | |
314 | ||
315 | return timespec_to_ktime(now); | |
316 | } | |
317 | EXPORT_SYMBOL_GPL(ktime_get); | |
318 | ||
319 | /** | |
320 | * ktime_get_ts - get the monotonic clock in timespec format | |
321 | * @ts: pointer to timespec variable | |
322 | * | |
323 | * The function calculates the monotonic clock from the realtime | |
324 | * clock and the wall_to_monotonic offset and stores the result | |
325 | * in normalized timespec format in the variable pointed to by @ts. | |
326 | */ | |
327 | void ktime_get_ts(struct timespec *ts) | |
328 | { | |
329 | struct timespec tomono; | |
330 | unsigned long seq; | |
331 | ||
332 | do { | |
333 | seq = read_seqbegin(&xtime_lock); | |
334 | getnstimeofday(ts); | |
335 | tomono = wall_to_monotonic; | |
336 | ||
337 | } while (read_seqretry(&xtime_lock, seq)); | |
338 | ||
339 | set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec, | |
340 | ts->tv_nsec + tomono.tv_nsec); | |
341 | } | |
342 | EXPORT_SYMBOL_GPL(ktime_get_ts); | |
343 | #endif /* !GENERIC_TIME */ | |
344 | ||
345 | /** | |
346 | * ktime_get_real - get the real (wall-) time in ktime_t format | |
347 | * | |
348 | * returns the time in ktime_t format | |
349 | */ | |
350 | ktime_t ktime_get_real(void) | |
351 | { | |
352 | struct timespec now; | |
353 | ||
354 | getnstimeofday(&now); | |
355 | ||
356 | return timespec_to_ktime(now); | |
357 | } | |
358 | EXPORT_SYMBOL_GPL(ktime_get_real); | |
8524070b | 359 | |
2d42244a JS |
360 | /** |
361 | * getrawmonotonic - Returns the raw monotonic time in a timespec | |
362 | * @ts: pointer to the timespec to be set | |
363 | * | |
364 | * Returns the raw monotonic time (completely un-modified by ntp) | |
365 | */ | |
366 | void getrawmonotonic(struct timespec *ts) | |
367 | { | |
368 | unsigned long seq; | |
369 | s64 nsecs; | |
370 | cycle_t cycle_now, cycle_delta; | |
371 | ||
372 | do { | |
373 | seq = read_seqbegin(&xtime_lock); | |
374 | ||
375 | /* read clocksource: */ | |
376 | cycle_now = clocksource_read(clock); | |
377 | ||
378 | /* calculate the delta since the last update_wall_time: */ | |
379 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; | |
380 | ||
381 | /* convert to nanoseconds: */ | |
382 | nsecs = ((s64)cycle_delta * clock->mult_orig) >> clock->shift; | |
383 | ||
384 | *ts = clock->raw_time; | |
385 | ||
386 | } while (read_seqretry(&xtime_lock, seq)); | |
387 | ||
388 | timespec_add_ns(ts, nsecs); | |
389 | } | |
390 | EXPORT_SYMBOL(getrawmonotonic); | |
391 | ||
392 | ||
8524070b | 393 | /** |
cf4fc6cb | 394 | * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres |
8524070b | 395 | */ |
cf4fc6cb | 396 | int timekeeping_valid_for_hres(void) |
8524070b | 397 | { |
398 | unsigned long seq; | |
399 | int ret; | |
400 | ||
401 | do { | |
402 | seq = read_seqbegin(&xtime_lock); | |
403 | ||
404 | ret = clock->flags & CLOCK_SOURCE_VALID_FOR_HRES; | |
405 | ||
406 | } while (read_seqretry(&xtime_lock, seq)); | |
407 | ||
408 | return ret; | |
409 | } | |
410 | ||
411 | /** | |
412 | * read_persistent_clock - Return time in seconds from the persistent clock. | |
413 | * | |
414 | * Weak dummy function for arches that do not yet support it. | |
415 | * Returns seconds from epoch using the battery backed persistent clock. | |
416 | * Returns zero if unsupported. | |
417 | * | |
418 | * XXX - Do be sure to remove it once all arches implement it. | |
419 | */ | |
420 | unsigned long __attribute__((weak)) read_persistent_clock(void) | |
421 | { | |
422 | return 0; | |
423 | } | |
424 | ||
425 | /* | |
426 | * timekeeping_init - Initializes the clocksource and common timekeeping values | |
427 | */ | |
428 | void __init timekeeping_init(void) | |
429 | { | |
430 | unsigned long flags; | |
431 | unsigned long sec = read_persistent_clock(); | |
432 | ||
433 | write_seqlock_irqsave(&xtime_lock, flags); | |
434 | ||
7dffa3c6 | 435 | ntp_init(); |
8524070b | 436 | |
437 | clock = clocksource_get_next(); | |
4614e6ad | 438 | clocksource_enable(clock); |
10a398d0 | 439 | clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH); |
8524070b | 440 | clock->cycle_last = clocksource_read(clock); |
441 | ||
442 | xtime.tv_sec = sec; | |
443 | xtime.tv_nsec = 0; | |
444 | set_normalized_timespec(&wall_to_monotonic, | |
445 | -xtime.tv_sec, -xtime.tv_nsec); | |
1001d0a9 | 446 | update_xtime_cache(0); |
7c3f1a57 | 447 | total_sleep_time = 0; |
8524070b | 448 | write_sequnlock_irqrestore(&xtime_lock, flags); |
449 | } | |
450 | ||
8524070b | 451 | /* time in seconds when suspend began */ |
452 | static unsigned long timekeeping_suspend_time; | |
453 | ||
454 | /** | |
455 | * timekeeping_resume - Resumes the generic timekeeping subsystem. | |
456 | * @dev: unused | |
457 | * | |
458 | * This is for the generic clocksource timekeeping. | |
459 | * xtime/wall_to_monotonic/jiffies/etc are | |
460 | * still managed by arch specific suspend/resume code. | |
461 | */ | |
462 | static int timekeeping_resume(struct sys_device *dev) | |
463 | { | |
464 | unsigned long flags; | |
465 | unsigned long now = read_persistent_clock(); | |
466 | ||
d10ff3fb TG |
467 | clocksource_resume(); |
468 | ||
8524070b | 469 | write_seqlock_irqsave(&xtime_lock, flags); |
470 | ||
471 | if (now && (now > timekeeping_suspend_time)) { | |
472 | unsigned long sleep_length = now - timekeeping_suspend_time; | |
473 | ||
474 | xtime.tv_sec += sleep_length; | |
475 | wall_to_monotonic.tv_sec -= sleep_length; | |
7c3f1a57 | 476 | total_sleep_time += sleep_length; |
8524070b | 477 | } |
1001d0a9 | 478 | update_xtime_cache(0); |
8524070b | 479 | /* re-base the last cycle value */ |
d8bb6f4c | 480 | clock->cycle_last = 0; |
8524070b | 481 | clock->cycle_last = clocksource_read(clock); |
482 | clock->error = 0; | |
483 | timekeeping_suspended = 0; | |
484 | write_sequnlock_irqrestore(&xtime_lock, flags); | |
485 | ||
486 | touch_softlockup_watchdog(); | |
487 | ||
488 | clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); | |
489 | ||
490 | /* Resume hrtimers */ | |
491 | hres_timers_resume(); | |
492 | ||
493 | return 0; | |
494 | } | |
495 | ||
496 | static int timekeeping_suspend(struct sys_device *dev, pm_message_t state) | |
497 | { | |
498 | unsigned long flags; | |
499 | ||
3be90950 TG |
500 | timekeeping_suspend_time = read_persistent_clock(); |
501 | ||
8524070b | 502 | write_seqlock_irqsave(&xtime_lock, flags); |
9a055117 | 503 | clocksource_forward_now(); |
8524070b | 504 | timekeeping_suspended = 1; |
8524070b | 505 | write_sequnlock_irqrestore(&xtime_lock, flags); |
506 | ||
507 | clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); | |
508 | ||
509 | return 0; | |
510 | } | |
511 | ||
512 | /* sysfs resume/suspend bits for timekeeping */ | |
513 | static struct sysdev_class timekeeping_sysclass = { | |
af5ca3f4 | 514 | .name = "timekeeping", |
8524070b | 515 | .resume = timekeeping_resume, |
516 | .suspend = timekeeping_suspend, | |
8524070b | 517 | }; |
518 | ||
519 | static struct sys_device device_timer = { | |
520 | .id = 0, | |
521 | .cls = &timekeeping_sysclass, | |
522 | }; | |
523 | ||
524 | static int __init timekeeping_init_device(void) | |
525 | { | |
526 | int error = sysdev_class_register(&timekeeping_sysclass); | |
527 | if (!error) | |
528 | error = sysdev_register(&device_timer); | |
529 | return error; | |
530 | } | |
531 | ||
532 | device_initcall(timekeeping_init_device); | |
533 | ||
534 | /* | |
535 | * If the error is already larger, we look ahead even further | |
536 | * to compensate for late or lost adjustments. | |
537 | */ | |
538 | static __always_inline int clocksource_bigadjust(s64 error, s64 *interval, | |
539 | s64 *offset) | |
540 | { | |
541 | s64 tick_error, i; | |
542 | u32 look_ahead, adj; | |
543 | s32 error2, mult; | |
544 | ||
545 | /* | |
546 | * Use the current error value to determine how much to look ahead. | |
547 | * The larger the error the slower we adjust for it to avoid problems | |
548 | * with losing too many ticks, otherwise we would overadjust and | |
549 | * produce an even larger error. The smaller the adjustment the | |
550 | * faster we try to adjust for it, as lost ticks can do less harm | |
3eb05676 | 551 | * here. This is tuned so that an error of about 1 msec is adjusted |
8524070b | 552 | * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks). |
553 | */ | |
7fc5c784 | 554 | error2 = clock->error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ); |
8524070b | 555 | error2 = abs(error2); |
556 | for (look_ahead = 0; error2 > 0; look_ahead++) | |
557 | error2 >>= 2; | |
558 | ||
559 | /* | |
560 | * Now calculate the error in (1 << look_ahead) ticks, but first | |
561 | * remove the single look ahead already included in the error. | |
562 | */ | |
8383c423 | 563 | tick_error = tick_length >> (NTP_SCALE_SHIFT - clock->shift + 1); |
8524070b | 564 | tick_error -= clock->xtime_interval >> 1; |
565 | error = ((error - tick_error) >> look_ahead) + tick_error; | |
566 | ||
567 | /* Finally calculate the adjustment shift value. */ | |
568 | i = *interval; | |
569 | mult = 1; | |
570 | if (error < 0) { | |
571 | error = -error; | |
572 | *interval = -*interval; | |
573 | *offset = -*offset; | |
574 | mult = -1; | |
575 | } | |
576 | for (adj = 0; error > i; adj++) | |
577 | error >>= 1; | |
578 | ||
579 | *interval <<= adj; | |
580 | *offset <<= adj; | |
581 | return mult << adj; | |
582 | } | |
583 | ||
584 | /* | |
585 | * Adjust the multiplier to reduce the error value, | |
586 | * this is optimized for the most common adjustments of -1,0,1, | |
587 | * for other values we can do a bit more work. | |
588 | */ | |
71120f18 | 589 | static void clocksource_adjust(s64 offset) |
8524070b | 590 | { |
591 | s64 error, interval = clock->cycle_interval; | |
592 | int adj; | |
593 | ||
7fc5c784 | 594 | error = clock->error >> (NTP_SCALE_SHIFT - clock->shift - 1); |
8524070b | 595 | if (error > interval) { |
596 | error >>= 2; | |
597 | if (likely(error <= interval)) | |
598 | adj = 1; | |
599 | else | |
600 | adj = clocksource_bigadjust(error, &interval, &offset); | |
601 | } else if (error < -interval) { | |
602 | error >>= 2; | |
603 | if (likely(error >= -interval)) { | |
604 | adj = -1; | |
605 | interval = -interval; | |
606 | offset = -offset; | |
607 | } else | |
608 | adj = clocksource_bigadjust(error, &interval, &offset); | |
609 | } else | |
610 | return; | |
611 | ||
612 | clock->mult += adj; | |
613 | clock->xtime_interval += interval; | |
614 | clock->xtime_nsec -= offset; | |
615 | clock->error -= (interval - offset) << | |
7fc5c784 | 616 | (NTP_SCALE_SHIFT - clock->shift); |
8524070b | 617 | } |
618 | ||
619 | /** | |
620 | * update_wall_time - Uses the current clocksource to increment the wall time | |
621 | * | |
622 | * Called from the timer interrupt, must hold a write on xtime_lock. | |
623 | */ | |
624 | void update_wall_time(void) | |
625 | { | |
626 | cycle_t offset; | |
627 | ||
628 | /* Make sure we're fully resumed: */ | |
629 | if (unlikely(timekeeping_suspended)) | |
630 | return; | |
631 | ||
632 | #ifdef CONFIG_GENERIC_TIME | |
633 | offset = (clocksource_read(clock) - clock->cycle_last) & clock->mask; | |
634 | #else | |
635 | offset = clock->cycle_interval; | |
636 | #endif | |
5cd1c9c5 | 637 | clock->xtime_nsec = (s64)xtime.tv_nsec << clock->shift; |
8524070b | 638 | |
639 | /* normally this loop will run just once, however in the | |
640 | * case of lost or late ticks, it will accumulate correctly. | |
641 | */ | |
642 | while (offset >= clock->cycle_interval) { | |
643 | /* accumulate one interval */ | |
8524070b | 644 | offset -= clock->cycle_interval; |
9a055117 | 645 | clock->cycle_last += clock->cycle_interval; |
8524070b | 646 | |
9a055117 | 647 | clock->xtime_nsec += clock->xtime_interval; |
8524070b | 648 | if (clock->xtime_nsec >= (u64)NSEC_PER_SEC << clock->shift) { |
649 | clock->xtime_nsec -= (u64)NSEC_PER_SEC << clock->shift; | |
650 | xtime.tv_sec++; | |
651 | second_overflow(); | |
652 | } | |
653 | ||
2d42244a JS |
654 | clock->raw_time.tv_nsec += clock->raw_interval; |
655 | if (clock->raw_time.tv_nsec >= NSEC_PER_SEC) { | |
656 | clock->raw_time.tv_nsec -= NSEC_PER_SEC; | |
657 | clock->raw_time.tv_sec++; | |
658 | } | |
659 | ||
8524070b | 660 | /* accumulate error between NTP and clock interval */ |
8383c423 | 661 | clock->error += tick_length; |
7fc5c784 | 662 | clock->error -= clock->xtime_interval << (NTP_SCALE_SHIFT - clock->shift); |
8524070b | 663 | } |
664 | ||
665 | /* correct the clock when NTP error is too big */ | |
71120f18 | 666 | clocksource_adjust(offset); |
8524070b | 667 | |
6c9bacb4 | 668 | /* |
669 | * Since in the loop above, we accumulate any amount of time | |
670 | * in xtime_nsec over a second into xtime.tv_sec, its possible for | |
671 | * xtime_nsec to be fairly small after the loop. Further, if we're | |
672 | * slightly speeding the clocksource up in clocksource_adjust(), | |
673 | * its possible the required corrective factor to xtime_nsec could | |
674 | * cause it to underflow. | |
675 | * | |
676 | * Now, we cannot simply roll the accumulated second back, since | |
677 | * the NTP subsystem has been notified via second_overflow. So | |
678 | * instead we push xtime_nsec forward by the amount we underflowed, | |
679 | * and add that amount into the error. | |
680 | * | |
681 | * We'll correct this error next time through this function, when | |
682 | * xtime_nsec is not as small. | |
683 | */ | |
684 | if (unlikely((s64)clock->xtime_nsec < 0)) { | |
685 | s64 neg = -(s64)clock->xtime_nsec; | |
686 | clock->xtime_nsec = 0; | |
687 | clock->error += neg << (NTP_SCALE_SHIFT - clock->shift); | |
688 | } | |
689 | ||
5cd1c9c5 RZ |
690 | /* store full nanoseconds into xtime after rounding it up and |
691 | * add the remainder to the error difference. | |
692 | */ | |
693 | xtime.tv_nsec = ((s64)clock->xtime_nsec >> clock->shift) + 1; | |
8524070b | 694 | clock->xtime_nsec -= (s64)xtime.tv_nsec << clock->shift; |
5cd1c9c5 | 695 | clock->error += clock->xtime_nsec << (NTP_SCALE_SHIFT - clock->shift); |
8524070b | 696 | |
17c38b74 | 697 | update_xtime_cache(cyc2ns(clock, offset)); |
698 | ||
8524070b | 699 | /* check to see if there is a new clocksource to use */ |
700 | change_clocksource(); | |
701 | update_vsyscall(&xtime, clock); | |
702 | } | |
7c3f1a57 TJ |
703 | |
704 | /** | |
705 | * getboottime - Return the real time of system boot. | |
706 | * @ts: pointer to the timespec to be set | |
707 | * | |
708 | * Returns the time of day in a timespec. | |
709 | * | |
710 | * This is based on the wall_to_monotonic offset and the total suspend | |
711 | * time. Calls to settimeofday will affect the value returned (which | |
712 | * basically means that however wrong your real time clock is at boot time, | |
713 | * you get the right time here). | |
714 | */ | |
715 | void getboottime(struct timespec *ts) | |
716 | { | |
717 | set_normalized_timespec(ts, | |
718 | - (wall_to_monotonic.tv_sec + total_sleep_time), | |
719 | - wall_to_monotonic.tv_nsec); | |
720 | } | |
721 | ||
722 | /** | |
723 | * monotonic_to_bootbased - Convert the monotonic time to boot based. | |
724 | * @ts: pointer to the timespec to be converted | |
725 | */ | |
726 | void monotonic_to_bootbased(struct timespec *ts) | |
727 | { | |
728 | ts->tv_sec += total_sleep_time; | |
729 | } | |
2c6b47de | 730 | |
17c38b74 | 731 | unsigned long get_seconds(void) |
732 | { | |
733 | return xtime_cache.tv_sec; | |
734 | } | |
735 | EXPORT_SYMBOL(get_seconds); | |
736 | ||
737 | ||
2c6b47de | 738 | struct timespec current_kernel_time(void) |
739 | { | |
740 | struct timespec now; | |
741 | unsigned long seq; | |
742 | ||
743 | do { | |
744 | seq = read_seqbegin(&xtime_lock); | |
745 | ||
17c38b74 | 746 | now = xtime_cache; |
2c6b47de | 747 | } while (read_seqretry(&xtime_lock, seq)); |
748 | ||
749 | return now; | |
750 | } | |
2c6b47de | 751 | EXPORT_SYMBOL(current_kernel_time); |