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Commit | Line | Data |
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8524070b JS |
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 | ||
155ec602 MS |
22 | /* Structure holding internal timekeeping values. */ |
23 | struct timekeeper { | |
24 | /* Current clocksource used for timekeeping. */ | |
25 | struct clocksource *clock; | |
23ce7211 MS |
26 | /* The shift value of the current clocksource. */ |
27 | int shift; | |
155ec602 MS |
28 | |
29 | /* Number of clock cycles in one NTP interval. */ | |
30 | cycle_t cycle_interval; | |
31 | /* Number of clock shifted nano seconds in one NTP interval. */ | |
32 | u64 xtime_interval; | |
33 | /* Raw nano seconds accumulated per NTP interval. */ | |
34 | u32 raw_interval; | |
35 | ||
36 | /* Clock shifted nano seconds remainder not stored in xtime.tv_nsec. */ | |
37 | u64 xtime_nsec; | |
38 | /* Difference between accumulated time and NTP time in ntp | |
39 | * shifted nano seconds. */ | |
40 | s64 ntp_error; | |
23ce7211 MS |
41 | /* Shift conversion between clock shifted nano seconds and |
42 | * ntp shifted nano seconds. */ | |
43 | int ntp_error_shift; | |
0a544198 MS |
44 | /* NTP adjusted clock multiplier */ |
45 | u32 mult; | |
155ec602 MS |
46 | }; |
47 | ||
48 | struct timekeeper timekeeper; | |
49 | ||
50 | /** | |
51 | * timekeeper_setup_internals - Set up internals to use clocksource clock. | |
52 | * | |
53 | * @clock: Pointer to clocksource. | |
54 | * | |
55 | * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment | |
56 | * pair and interval request. | |
57 | * | |
58 | * Unless you're the timekeeping code, you should not be using this! | |
59 | */ | |
60 | static void timekeeper_setup_internals(struct clocksource *clock) | |
61 | { | |
62 | cycle_t interval; | |
63 | u64 tmp; | |
64 | ||
65 | timekeeper.clock = clock; | |
66 | clock->cycle_last = clock->read(clock); | |
67 | ||
68 | /* Do the ns -> cycle conversion first, using original mult */ | |
69 | tmp = NTP_INTERVAL_LENGTH; | |
70 | tmp <<= clock->shift; | |
0a544198 MS |
71 | tmp += clock->mult/2; |
72 | do_div(tmp, clock->mult); | |
155ec602 MS |
73 | if (tmp == 0) |
74 | tmp = 1; | |
75 | ||
76 | interval = (cycle_t) tmp; | |
77 | timekeeper.cycle_interval = interval; | |
78 | ||
79 | /* Go back from cycles -> shifted ns */ | |
80 | timekeeper.xtime_interval = (u64) interval * clock->mult; | |
81 | timekeeper.raw_interval = | |
0a544198 | 82 | ((u64) interval * clock->mult) >> clock->shift; |
155ec602 MS |
83 | |
84 | timekeeper.xtime_nsec = 0; | |
23ce7211 | 85 | timekeeper.shift = clock->shift; |
155ec602 MS |
86 | |
87 | timekeeper.ntp_error = 0; | |
23ce7211 | 88 | timekeeper.ntp_error_shift = NTP_SCALE_SHIFT - clock->shift; |
0a544198 MS |
89 | |
90 | /* | |
91 | * The timekeeper keeps its own mult values for the currently | |
92 | * active clocksource. These value will be adjusted via NTP | |
93 | * to counteract clock drifting. | |
94 | */ | |
95 | timekeeper.mult = clock->mult; | |
155ec602 | 96 | } |
8524070b | 97 | |
2ba2a305 MS |
98 | /* Timekeeper helper functions. */ |
99 | static inline s64 timekeeping_get_ns(void) | |
100 | { | |
101 | cycle_t cycle_now, cycle_delta; | |
102 | struct clocksource *clock; | |
103 | ||
104 | /* read clocksource: */ | |
105 | clock = timekeeper.clock; | |
106 | cycle_now = clock->read(clock); | |
107 | ||
108 | /* calculate the delta since the last update_wall_time: */ | |
109 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; | |
110 | ||
111 | /* return delta convert to nanoseconds using ntp adjusted mult. */ | |
112 | return clocksource_cyc2ns(cycle_delta, timekeeper.mult, | |
113 | timekeeper.shift); | |
114 | } | |
115 | ||
116 | static inline s64 timekeeping_get_ns_raw(void) | |
117 | { | |
118 | cycle_t cycle_now, cycle_delta; | |
119 | struct clocksource *clock; | |
120 | ||
121 | /* read clocksource: */ | |
122 | clock = timekeeper.clock; | |
123 | cycle_now = clock->read(clock); | |
124 | ||
125 | /* calculate the delta since the last update_wall_time: */ | |
126 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; | |
127 | ||
128 | /* return delta convert to nanoseconds using ntp adjusted mult. */ | |
129 | return clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift); | |
130 | } | |
131 | ||
8524070b JS |
132 | /* |
133 | * This read-write spinlock protects us from races in SMP while | |
dce48a84 | 134 | * playing with xtime. |
8524070b | 135 | */ |
ba2a631b | 136 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock); |
8524070b JS |
137 | |
138 | ||
139 | /* | |
140 | * The current time | |
141 | * wall_to_monotonic is what we need to add to xtime (or xtime corrected | |
142 | * for sub jiffie times) to get to monotonic time. Monotonic is pegged | |
143 | * at zero at system boot time, so wall_to_monotonic will be negative, | |
144 | * however, we will ALWAYS keep the tv_nsec part positive so we can use | |
145 | * the usual normalization. | |
7c3f1a57 TJ |
146 | * |
147 | * wall_to_monotonic is moved after resume from suspend for the monotonic | |
148 | * time not to jump. We need to add total_sleep_time to wall_to_monotonic | |
149 | * to get the real boot based time offset. | |
150 | * | |
151 | * - wall_to_monotonic is no longer the boot time, getboottime must be | |
152 | * used instead. | |
8524070b JS |
153 | */ |
154 | struct timespec xtime __attribute__ ((aligned (16))); | |
155 | struct timespec wall_to_monotonic __attribute__ ((aligned (16))); | |
7c3f1a57 | 156 | static unsigned long total_sleep_time; /* seconds */ |
8524070b | 157 | |
155ec602 MS |
158 | /* |
159 | * The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. | |
160 | */ | |
161 | struct timespec raw_time; | |
162 | ||
1c5745aa TG |
163 | /* flag for if timekeeping is suspended */ |
164 | int __read_mostly timekeeping_suspended; | |
165 | ||
17c38b74 | 166 | static struct timespec xtime_cache __attribute__ ((aligned (16))); |
1001d0a9 | 167 | void update_xtime_cache(u64 nsec) |
17c38b74 JS |
168 | { |
169 | xtime_cache = xtime; | |
170 | timespec_add_ns(&xtime_cache, nsec); | |
171 | } | |
17c38b74 | 172 | |
31089c13 JS |
173 | /* must hold xtime_lock */ |
174 | void timekeeping_leap_insert(int leapsecond) | |
175 | { | |
176 | xtime.tv_sec += leapsecond; | |
177 | wall_to_monotonic.tv_sec -= leapsecond; | |
155ec602 | 178 | update_vsyscall(&xtime, timekeeper.clock); |
31089c13 | 179 | } |
8524070b JS |
180 | |
181 | #ifdef CONFIG_GENERIC_TIME | |
182 | /** | |
155ec602 | 183 | * timekeeping_forward_now - update clock to the current time |
8524070b | 184 | * |
9a055117 RZ |
185 | * Forward the current clock to update its state since the last call to |
186 | * update_wall_time(). This is useful before significant clock changes, | |
187 | * as it avoids having to deal with this time offset explicitly. | |
8524070b | 188 | */ |
155ec602 | 189 | static void timekeeping_forward_now(void) |
8524070b JS |
190 | { |
191 | cycle_t cycle_now, cycle_delta; | |
155ec602 | 192 | struct clocksource *clock; |
9a055117 | 193 | s64 nsec; |
8524070b | 194 | |
155ec602 | 195 | clock = timekeeper.clock; |
a0f7d48b | 196 | cycle_now = clock->read(clock); |
8524070b | 197 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; |
9a055117 | 198 | clock->cycle_last = cycle_now; |
8524070b | 199 | |
0a544198 MS |
200 | nsec = clocksource_cyc2ns(cycle_delta, timekeeper.mult, |
201 | timekeeper.shift); | |
7d27558c JS |
202 | |
203 | /* If arch requires, add in gettimeoffset() */ | |
204 | nsec += arch_gettimeoffset(); | |
205 | ||
9a055117 | 206 | timespec_add_ns(&xtime, nsec); |
2d42244a | 207 | |
0a544198 | 208 | nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift); |
155ec602 | 209 | timespec_add_ns(&raw_time, nsec); |
8524070b JS |
210 | } |
211 | ||
212 | /** | |
efd9ac86 | 213 | * getnstimeofday - Returns the time of day in a timespec |
8524070b JS |
214 | * @ts: pointer to the timespec to be set |
215 | * | |
efd9ac86 | 216 | * Returns the time of day in a timespec. |
8524070b | 217 | */ |
efd9ac86 | 218 | void getnstimeofday(struct timespec *ts) |
8524070b JS |
219 | { |
220 | unsigned long seq; | |
221 | s64 nsecs; | |
222 | ||
1c5745aa TG |
223 | WARN_ON(timekeeping_suspended); |
224 | ||
8524070b JS |
225 | do { |
226 | seq = read_seqbegin(&xtime_lock); | |
227 | ||
228 | *ts = xtime; | |
2ba2a305 | 229 | nsecs = timekeeping_get_ns(); |
8524070b | 230 | |
7d27558c JS |
231 | /* If arch requires, add in gettimeoffset() */ |
232 | nsecs += arch_gettimeoffset(); | |
233 | ||
8524070b JS |
234 | } while (read_seqretry(&xtime_lock, seq)); |
235 | ||
236 | timespec_add_ns(ts, nsecs); | |
237 | } | |
238 | ||
8524070b JS |
239 | EXPORT_SYMBOL(getnstimeofday); |
240 | ||
951ed4d3 MS |
241 | ktime_t ktime_get(void) |
242 | { | |
951ed4d3 MS |
243 | unsigned int seq; |
244 | s64 secs, nsecs; | |
245 | ||
246 | WARN_ON(timekeeping_suspended); | |
247 | ||
248 | do { | |
249 | seq = read_seqbegin(&xtime_lock); | |
250 | secs = xtime.tv_sec + wall_to_monotonic.tv_sec; | |
251 | nsecs = xtime.tv_nsec + wall_to_monotonic.tv_nsec; | |
2ba2a305 | 252 | nsecs += timekeeping_get_ns(); |
951ed4d3 MS |
253 | |
254 | } while (read_seqretry(&xtime_lock, seq)); | |
255 | /* | |
256 | * Use ktime_set/ktime_add_ns to create a proper ktime on | |
257 | * 32-bit architectures without CONFIG_KTIME_SCALAR. | |
258 | */ | |
259 | return ktime_add_ns(ktime_set(secs, 0), nsecs); | |
260 | } | |
261 | EXPORT_SYMBOL_GPL(ktime_get); | |
262 | ||
263 | /** | |
264 | * ktime_get_ts - get the monotonic clock in timespec format | |
265 | * @ts: pointer to timespec variable | |
266 | * | |
267 | * The function calculates the monotonic clock from the realtime | |
268 | * clock and the wall_to_monotonic offset and stores the result | |
269 | * in normalized timespec format in the variable pointed to by @ts. | |
270 | */ | |
271 | void ktime_get_ts(struct timespec *ts) | |
272 | { | |
951ed4d3 MS |
273 | struct timespec tomono; |
274 | unsigned int seq; | |
275 | s64 nsecs; | |
276 | ||
277 | WARN_ON(timekeeping_suspended); | |
278 | ||
279 | do { | |
280 | seq = read_seqbegin(&xtime_lock); | |
281 | *ts = xtime; | |
282 | tomono = wall_to_monotonic; | |
2ba2a305 | 283 | nsecs = timekeeping_get_ns(); |
951ed4d3 MS |
284 | |
285 | } while (read_seqretry(&xtime_lock, seq)); | |
286 | ||
287 | set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec, | |
288 | ts->tv_nsec + tomono.tv_nsec + nsecs); | |
289 | } | |
290 | EXPORT_SYMBOL_GPL(ktime_get_ts); | |
291 | ||
8524070b JS |
292 | /** |
293 | * do_gettimeofday - Returns the time of day in a timeval | |
294 | * @tv: pointer to the timeval to be set | |
295 | * | |
efd9ac86 | 296 | * NOTE: Users should be converted to using getnstimeofday() |
8524070b JS |
297 | */ |
298 | void do_gettimeofday(struct timeval *tv) | |
299 | { | |
300 | struct timespec now; | |
301 | ||
efd9ac86 | 302 | getnstimeofday(&now); |
8524070b JS |
303 | tv->tv_sec = now.tv_sec; |
304 | tv->tv_usec = now.tv_nsec/1000; | |
305 | } | |
306 | ||
307 | EXPORT_SYMBOL(do_gettimeofday); | |
308 | /** | |
309 | * do_settimeofday - Sets the time of day | |
310 | * @tv: pointer to the timespec variable containing the new time | |
311 | * | |
312 | * Sets the time of day to the new time and update NTP and notify hrtimers | |
313 | */ | |
314 | int do_settimeofday(struct timespec *tv) | |
315 | { | |
9a055117 | 316 | struct timespec ts_delta; |
8524070b | 317 | unsigned long flags; |
8524070b JS |
318 | |
319 | if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) | |
320 | return -EINVAL; | |
321 | ||
322 | write_seqlock_irqsave(&xtime_lock, flags); | |
323 | ||
155ec602 | 324 | timekeeping_forward_now(); |
9a055117 RZ |
325 | |
326 | ts_delta.tv_sec = tv->tv_sec - xtime.tv_sec; | |
327 | ts_delta.tv_nsec = tv->tv_nsec - xtime.tv_nsec; | |
328 | wall_to_monotonic = timespec_sub(wall_to_monotonic, ts_delta); | |
8524070b | 329 | |
9a055117 | 330 | xtime = *tv; |
8524070b | 331 | |
1001d0a9 | 332 | update_xtime_cache(0); |
8524070b | 333 | |
155ec602 | 334 | timekeeper.ntp_error = 0; |
8524070b JS |
335 | ntp_clear(); |
336 | ||
155ec602 | 337 | update_vsyscall(&xtime, timekeeper.clock); |
8524070b JS |
338 | |
339 | write_sequnlock_irqrestore(&xtime_lock, flags); | |
340 | ||
341 | /* signal hrtimers about time change */ | |
342 | clock_was_set(); | |
343 | ||
344 | return 0; | |
345 | } | |
346 | ||
347 | EXPORT_SYMBOL(do_settimeofday); | |
348 | ||
349 | /** | |
350 | * change_clocksource - Swaps clocksources if a new one is available | |
351 | * | |
352 | * Accumulates current time interval and initializes new clocksource | |
353 | */ | |
354 | static void change_clocksource(void) | |
355 | { | |
4614e6ad | 356 | struct clocksource *new, *old; |
8524070b JS |
357 | |
358 | new = clocksource_get_next(); | |
359 | ||
155ec602 | 360 | if (!new || timekeeper.clock == new) |
8524070b JS |
361 | return; |
362 | ||
155ec602 | 363 | timekeeping_forward_now(); |
8524070b | 364 | |
a0f7d48b | 365 | if (new->enable && !new->enable(new)) |
4614e6ad | 366 | return; |
2d42244a | 367 | |
155ec602 MS |
368 | old = timekeeper.clock; |
369 | timekeeper_setup_internals(new); | |
370 | ||
a0f7d48b MS |
371 | if (old->disable) |
372 | old->disable(old); | |
4614e6ad | 373 | |
8524070b | 374 | tick_clock_notify(); |
8524070b | 375 | } |
a40f262c | 376 | #else /* GENERIC_TIME */ |
155ec602 | 377 | static inline void timekeeping_forward_now(void) { } |
8524070b | 378 | static inline void change_clocksource(void) { } |
a40f262c TG |
379 | |
380 | /** | |
381 | * ktime_get - get the monotonic time in ktime_t format | |
382 | * | |
383 | * returns the time in ktime_t format | |
384 | */ | |
385 | ktime_t ktime_get(void) | |
386 | { | |
387 | struct timespec now; | |
388 | ||
389 | ktime_get_ts(&now); | |
390 | ||
391 | return timespec_to_ktime(now); | |
392 | } | |
393 | EXPORT_SYMBOL_GPL(ktime_get); | |
394 | ||
395 | /** | |
396 | * ktime_get_ts - get the monotonic clock in timespec format | |
397 | * @ts: pointer to timespec variable | |
398 | * | |
399 | * The function calculates the monotonic clock from the realtime | |
400 | * clock and the wall_to_monotonic offset and stores the result | |
401 | * in normalized timespec format in the variable pointed to by @ts. | |
402 | */ | |
403 | void ktime_get_ts(struct timespec *ts) | |
404 | { | |
405 | struct timespec tomono; | |
406 | unsigned long seq; | |
407 | ||
408 | do { | |
409 | seq = read_seqbegin(&xtime_lock); | |
410 | getnstimeofday(ts); | |
411 | tomono = wall_to_monotonic; | |
412 | ||
413 | } while (read_seqretry(&xtime_lock, seq)); | |
414 | ||
415 | set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec, | |
416 | ts->tv_nsec + tomono.tv_nsec); | |
417 | } | |
418 | EXPORT_SYMBOL_GPL(ktime_get_ts); | |
419 | #endif /* !GENERIC_TIME */ | |
420 | ||
421 | /** | |
422 | * ktime_get_real - get the real (wall-) time in ktime_t format | |
423 | * | |
424 | * returns the time in ktime_t format | |
425 | */ | |
426 | ktime_t ktime_get_real(void) | |
427 | { | |
428 | struct timespec now; | |
429 | ||
430 | getnstimeofday(&now); | |
431 | ||
432 | return timespec_to_ktime(now); | |
433 | } | |
434 | EXPORT_SYMBOL_GPL(ktime_get_real); | |
8524070b | 435 | |
2d42244a JS |
436 | /** |
437 | * getrawmonotonic - Returns the raw monotonic time in a timespec | |
438 | * @ts: pointer to the timespec to be set | |
439 | * | |
440 | * Returns the raw monotonic time (completely un-modified by ntp) | |
441 | */ | |
442 | void getrawmonotonic(struct timespec *ts) | |
443 | { | |
444 | unsigned long seq; | |
445 | s64 nsecs; | |
2d42244a JS |
446 | |
447 | do { | |
448 | seq = read_seqbegin(&xtime_lock); | |
2ba2a305 | 449 | nsecs = timekeeping_get_ns_raw(); |
155ec602 | 450 | *ts = raw_time; |
2d42244a JS |
451 | |
452 | } while (read_seqretry(&xtime_lock, seq)); | |
453 | ||
454 | timespec_add_ns(ts, nsecs); | |
455 | } | |
456 | EXPORT_SYMBOL(getrawmonotonic); | |
457 | ||
458 | ||
8524070b | 459 | /** |
cf4fc6cb | 460 | * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres |
8524070b | 461 | */ |
cf4fc6cb | 462 | int timekeeping_valid_for_hres(void) |
8524070b JS |
463 | { |
464 | unsigned long seq; | |
465 | int ret; | |
466 | ||
467 | do { | |
468 | seq = read_seqbegin(&xtime_lock); | |
469 | ||
155ec602 | 470 | ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES; |
8524070b JS |
471 | |
472 | } while (read_seqretry(&xtime_lock, seq)); | |
473 | ||
474 | return ret; | |
475 | } | |
476 | ||
477 | /** | |
478 | * read_persistent_clock - Return time in seconds from the persistent clock. | |
479 | * | |
480 | * Weak dummy function for arches that do not yet support it. | |
481 | * Returns seconds from epoch using the battery backed persistent clock. | |
482 | * Returns zero if unsupported. | |
483 | * | |
484 | * XXX - Do be sure to remove it once all arches implement it. | |
485 | */ | |
486 | unsigned long __attribute__((weak)) read_persistent_clock(void) | |
487 | { | |
488 | return 0; | |
489 | } | |
490 | ||
491 | /* | |
492 | * timekeeping_init - Initializes the clocksource and common timekeeping values | |
493 | */ | |
494 | void __init timekeeping_init(void) | |
495 | { | |
155ec602 | 496 | struct clocksource *clock; |
8524070b JS |
497 | unsigned long flags; |
498 | unsigned long sec = read_persistent_clock(); | |
499 | ||
500 | write_seqlock_irqsave(&xtime_lock, flags); | |
501 | ||
7dffa3c6 | 502 | ntp_init(); |
8524070b | 503 | |
f1b82746 | 504 | clock = clocksource_default_clock(); |
a0f7d48b MS |
505 | if (clock->enable) |
506 | clock->enable(clock); | |
155ec602 | 507 | timekeeper_setup_internals(clock); |
8524070b JS |
508 | |
509 | xtime.tv_sec = sec; | |
510 | xtime.tv_nsec = 0; | |
155ec602 MS |
511 | raw_time.tv_sec = 0; |
512 | raw_time.tv_nsec = 0; | |
8524070b JS |
513 | set_normalized_timespec(&wall_to_monotonic, |
514 | -xtime.tv_sec, -xtime.tv_nsec); | |
1001d0a9 | 515 | update_xtime_cache(0); |
7c3f1a57 | 516 | total_sleep_time = 0; |
8524070b JS |
517 | write_sequnlock_irqrestore(&xtime_lock, flags); |
518 | } | |
519 | ||
8524070b JS |
520 | /* time in seconds when suspend began */ |
521 | static unsigned long timekeeping_suspend_time; | |
522 | ||
523 | /** | |
524 | * timekeeping_resume - Resumes the generic timekeeping subsystem. | |
525 | * @dev: unused | |
526 | * | |
527 | * This is for the generic clocksource timekeeping. | |
528 | * xtime/wall_to_monotonic/jiffies/etc are | |
529 | * still managed by arch specific suspend/resume code. | |
530 | */ | |
531 | static int timekeeping_resume(struct sys_device *dev) | |
532 | { | |
533 | unsigned long flags; | |
534 | unsigned long now = read_persistent_clock(); | |
535 | ||
d10ff3fb TG |
536 | clocksource_resume(); |
537 | ||
8524070b JS |
538 | write_seqlock_irqsave(&xtime_lock, flags); |
539 | ||
540 | if (now && (now > timekeeping_suspend_time)) { | |
541 | unsigned long sleep_length = now - timekeeping_suspend_time; | |
542 | ||
543 | xtime.tv_sec += sleep_length; | |
544 | wall_to_monotonic.tv_sec -= sleep_length; | |
7c3f1a57 | 545 | total_sleep_time += sleep_length; |
8524070b | 546 | } |
1001d0a9 | 547 | update_xtime_cache(0); |
8524070b | 548 | /* re-base the last cycle value */ |
155ec602 MS |
549 | timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock); |
550 | timekeeper.ntp_error = 0; | |
8524070b JS |
551 | timekeeping_suspended = 0; |
552 | write_sequnlock_irqrestore(&xtime_lock, flags); | |
553 | ||
554 | touch_softlockup_watchdog(); | |
555 | ||
556 | clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); | |
557 | ||
558 | /* Resume hrtimers */ | |
559 | hres_timers_resume(); | |
560 | ||
561 | return 0; | |
562 | } | |
563 | ||
564 | static int timekeeping_suspend(struct sys_device *dev, pm_message_t state) | |
565 | { | |
566 | unsigned long flags; | |
567 | ||
3be90950 TG |
568 | timekeeping_suspend_time = read_persistent_clock(); |
569 | ||
8524070b | 570 | write_seqlock_irqsave(&xtime_lock, flags); |
155ec602 | 571 | timekeeping_forward_now(); |
8524070b | 572 | timekeeping_suspended = 1; |
8524070b JS |
573 | write_sequnlock_irqrestore(&xtime_lock, flags); |
574 | ||
575 | clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); | |
576 | ||
577 | return 0; | |
578 | } | |
579 | ||
580 | /* sysfs resume/suspend bits for timekeeping */ | |
581 | static struct sysdev_class timekeeping_sysclass = { | |
af5ca3f4 | 582 | .name = "timekeeping", |
8524070b JS |
583 | .resume = timekeeping_resume, |
584 | .suspend = timekeeping_suspend, | |
8524070b JS |
585 | }; |
586 | ||
587 | static struct sys_device device_timer = { | |
588 | .id = 0, | |
589 | .cls = &timekeeping_sysclass, | |
590 | }; | |
591 | ||
592 | static int __init timekeeping_init_device(void) | |
593 | { | |
594 | int error = sysdev_class_register(&timekeeping_sysclass); | |
595 | if (!error) | |
596 | error = sysdev_register(&device_timer); | |
597 | return error; | |
598 | } | |
599 | ||
600 | device_initcall(timekeeping_init_device); | |
601 | ||
602 | /* | |
603 | * If the error is already larger, we look ahead even further | |
604 | * to compensate for late or lost adjustments. | |
605 | */ | |
155ec602 | 606 | static __always_inline int timekeeping_bigadjust(s64 error, s64 *interval, |
8524070b JS |
607 | s64 *offset) |
608 | { | |
609 | s64 tick_error, i; | |
610 | u32 look_ahead, adj; | |
611 | s32 error2, mult; | |
612 | ||
613 | /* | |
614 | * Use the current error value to determine how much to look ahead. | |
615 | * The larger the error the slower we adjust for it to avoid problems | |
616 | * with losing too many ticks, otherwise we would overadjust and | |
617 | * produce an even larger error. The smaller the adjustment the | |
618 | * faster we try to adjust for it, as lost ticks can do less harm | |
3eb05676 | 619 | * here. This is tuned so that an error of about 1 msec is adjusted |
8524070b JS |
620 | * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks). |
621 | */ | |
155ec602 | 622 | error2 = timekeeper.ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ); |
8524070b JS |
623 | error2 = abs(error2); |
624 | for (look_ahead = 0; error2 > 0; look_ahead++) | |
625 | error2 >>= 2; | |
626 | ||
627 | /* | |
628 | * Now calculate the error in (1 << look_ahead) ticks, but first | |
629 | * remove the single look ahead already included in the error. | |
630 | */ | |
23ce7211 | 631 | tick_error = tick_length >> (timekeeper.ntp_error_shift + 1); |
155ec602 | 632 | tick_error -= timekeeper.xtime_interval >> 1; |
8524070b JS |
633 | error = ((error - tick_error) >> look_ahead) + tick_error; |
634 | ||
635 | /* Finally calculate the adjustment shift value. */ | |
636 | i = *interval; | |
637 | mult = 1; | |
638 | if (error < 0) { | |
639 | error = -error; | |
640 | *interval = -*interval; | |
641 | *offset = -*offset; | |
642 | mult = -1; | |
643 | } | |
644 | for (adj = 0; error > i; adj++) | |
645 | error >>= 1; | |
646 | ||
647 | *interval <<= adj; | |
648 | *offset <<= adj; | |
649 | return mult << adj; | |
650 | } | |
651 | ||
652 | /* | |
653 | * Adjust the multiplier to reduce the error value, | |
654 | * this is optimized for the most common adjustments of -1,0,1, | |
655 | * for other values we can do a bit more work. | |
656 | */ | |
155ec602 | 657 | static void timekeeping_adjust(s64 offset) |
8524070b | 658 | { |
155ec602 | 659 | s64 error, interval = timekeeper.cycle_interval; |
8524070b JS |
660 | int adj; |
661 | ||
23ce7211 | 662 | error = timekeeper.ntp_error >> (timekeeper.ntp_error_shift - 1); |
8524070b JS |
663 | if (error > interval) { |
664 | error >>= 2; | |
665 | if (likely(error <= interval)) | |
666 | adj = 1; | |
667 | else | |
155ec602 | 668 | adj = timekeeping_bigadjust(error, &interval, &offset); |
8524070b JS |
669 | } else if (error < -interval) { |
670 | error >>= 2; | |
671 | if (likely(error >= -interval)) { | |
672 | adj = -1; | |
673 | interval = -interval; | |
674 | offset = -offset; | |
675 | } else | |
155ec602 | 676 | adj = timekeeping_bigadjust(error, &interval, &offset); |
8524070b JS |
677 | } else |
678 | return; | |
679 | ||
0a544198 | 680 | timekeeper.mult += adj; |
155ec602 MS |
681 | timekeeper.xtime_interval += interval; |
682 | timekeeper.xtime_nsec -= offset; | |
683 | timekeeper.ntp_error -= (interval - offset) << | |
23ce7211 | 684 | timekeeper.ntp_error_shift; |
8524070b JS |
685 | } |
686 | ||
687 | /** | |
688 | * update_wall_time - Uses the current clocksource to increment the wall time | |
689 | * | |
690 | * Called from the timer interrupt, must hold a write on xtime_lock. | |
691 | */ | |
692 | void update_wall_time(void) | |
693 | { | |
155ec602 | 694 | struct clocksource *clock; |
8524070b | 695 | cycle_t offset; |
23ce7211 | 696 | u64 nsecs; |
8524070b JS |
697 | |
698 | /* Make sure we're fully resumed: */ | |
699 | if (unlikely(timekeeping_suspended)) | |
700 | return; | |
701 | ||
155ec602 | 702 | clock = timekeeper.clock; |
8524070b | 703 | #ifdef CONFIG_GENERIC_TIME |
a0f7d48b | 704 | offset = (clock->read(clock) - clock->cycle_last) & clock->mask; |
8524070b | 705 | #else |
155ec602 | 706 | offset = timekeeper.cycle_interval; |
8524070b | 707 | #endif |
23ce7211 | 708 | timekeeper.xtime_nsec = (s64)xtime.tv_nsec << timekeeper.shift; |
8524070b JS |
709 | |
710 | /* normally this loop will run just once, however in the | |
711 | * case of lost or late ticks, it will accumulate correctly. | |
712 | */ | |
155ec602 | 713 | while (offset >= timekeeper.cycle_interval) { |
23ce7211 | 714 | u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift; |
155ec602 | 715 | |
8524070b | 716 | /* accumulate one interval */ |
155ec602 MS |
717 | offset -= timekeeper.cycle_interval; |
718 | clock->cycle_last += timekeeper.cycle_interval; | |
8524070b | 719 | |
155ec602 MS |
720 | timekeeper.xtime_nsec += timekeeper.xtime_interval; |
721 | if (timekeeper.xtime_nsec >= nsecps) { | |
722 | timekeeper.xtime_nsec -= nsecps; | |
8524070b JS |
723 | xtime.tv_sec++; |
724 | second_overflow(); | |
725 | } | |
726 | ||
155ec602 MS |
727 | raw_time.tv_nsec += timekeeper.raw_interval; |
728 | if (raw_time.tv_nsec >= NSEC_PER_SEC) { | |
729 | raw_time.tv_nsec -= NSEC_PER_SEC; | |
730 | raw_time.tv_sec++; | |
2d42244a JS |
731 | } |
732 | ||
8524070b | 733 | /* accumulate error between NTP and clock interval */ |
155ec602 MS |
734 | timekeeper.ntp_error += tick_length; |
735 | timekeeper.ntp_error -= timekeeper.xtime_interval << | |
23ce7211 | 736 | timekeeper.ntp_error_shift; |
8524070b JS |
737 | } |
738 | ||
739 | /* correct the clock when NTP error is too big */ | |
155ec602 | 740 | timekeeping_adjust(offset); |
8524070b | 741 | |
6c9bacb4 JS |
742 | /* |
743 | * Since in the loop above, we accumulate any amount of time | |
744 | * in xtime_nsec over a second into xtime.tv_sec, its possible for | |
745 | * xtime_nsec to be fairly small after the loop. Further, if we're | |
155ec602 | 746 | * slightly speeding the clocksource up in timekeeping_adjust(), |
6c9bacb4 JS |
747 | * its possible the required corrective factor to xtime_nsec could |
748 | * cause it to underflow. | |
749 | * | |
750 | * Now, we cannot simply roll the accumulated second back, since | |
751 | * the NTP subsystem has been notified via second_overflow. So | |
752 | * instead we push xtime_nsec forward by the amount we underflowed, | |
753 | * and add that amount into the error. | |
754 | * | |
755 | * We'll correct this error next time through this function, when | |
756 | * xtime_nsec is not as small. | |
757 | */ | |
155ec602 MS |
758 | if (unlikely((s64)timekeeper.xtime_nsec < 0)) { |
759 | s64 neg = -(s64)timekeeper.xtime_nsec; | |
760 | timekeeper.xtime_nsec = 0; | |
23ce7211 | 761 | timekeeper.ntp_error += neg << timekeeper.ntp_error_shift; |
6c9bacb4 JS |
762 | } |
763 | ||
5cd1c9c5 RZ |
764 | /* store full nanoseconds into xtime after rounding it up and |
765 | * add the remainder to the error difference. | |
766 | */ | |
23ce7211 MS |
767 | xtime.tv_nsec = ((s64) timekeeper.xtime_nsec >> timekeeper.shift) + 1; |
768 | timekeeper.xtime_nsec -= (s64) xtime.tv_nsec << timekeeper.shift; | |
769 | timekeeper.ntp_error += timekeeper.xtime_nsec << | |
770 | timekeeper.ntp_error_shift; | |
8524070b | 771 | |
0a544198 | 772 | nsecs = clocksource_cyc2ns(offset, timekeeper.mult, timekeeper.shift); |
155ec602 | 773 | update_xtime_cache(nsecs); |
17c38b74 | 774 | |
8524070b JS |
775 | /* check to see if there is a new clocksource to use */ |
776 | change_clocksource(); | |
155ec602 | 777 | update_vsyscall(&xtime, timekeeper.clock); |
8524070b | 778 | } |
7c3f1a57 TJ |
779 | |
780 | /** | |
781 | * getboottime - Return the real time of system boot. | |
782 | * @ts: pointer to the timespec to be set | |
783 | * | |
784 | * Returns the time of day in a timespec. | |
785 | * | |
786 | * This is based on the wall_to_monotonic offset and the total suspend | |
787 | * time. Calls to settimeofday will affect the value returned (which | |
788 | * basically means that however wrong your real time clock is at boot time, | |
789 | * you get the right time here). | |
790 | */ | |
791 | void getboottime(struct timespec *ts) | |
792 | { | |
793 | set_normalized_timespec(ts, | |
794 | - (wall_to_monotonic.tv_sec + total_sleep_time), | |
795 | - wall_to_monotonic.tv_nsec); | |
796 | } | |
797 | ||
798 | /** | |
799 | * monotonic_to_bootbased - Convert the monotonic time to boot based. | |
800 | * @ts: pointer to the timespec to be converted | |
801 | */ | |
802 | void monotonic_to_bootbased(struct timespec *ts) | |
803 | { | |
804 | ts->tv_sec += total_sleep_time; | |
805 | } | |
2c6b47de | 806 | |
17c38b74 JS |
807 | unsigned long get_seconds(void) |
808 | { | |
809 | return xtime_cache.tv_sec; | |
810 | } | |
811 | EXPORT_SYMBOL(get_seconds); | |
812 | ||
813 | ||
2c6b47de JS |
814 | struct timespec current_kernel_time(void) |
815 | { | |
816 | struct timespec now; | |
817 | unsigned long seq; | |
818 | ||
819 | do { | |
820 | seq = read_seqbegin(&xtime_lock); | |
821 | ||
17c38b74 | 822 | now = xtime_cache; |
2c6b47de JS |
823 | } while (read_seqretry(&xtime_lock, seq)); |
824 | ||
825 | return now; | |
826 | } | |
2c6b47de | 827 | EXPORT_SYMBOL(current_kernel_time); |