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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; | |
155ec602 MS |
44 | }; |
45 | ||
46 | struct timekeeper timekeeper; | |
47 | ||
48 | /** | |
49 | * timekeeper_setup_internals - Set up internals to use clocksource clock. | |
50 | * | |
51 | * @clock: Pointer to clocksource. | |
52 | * | |
53 | * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment | |
54 | * pair and interval request. | |
55 | * | |
56 | * Unless you're the timekeeping code, you should not be using this! | |
57 | */ | |
58 | static void timekeeper_setup_internals(struct clocksource *clock) | |
59 | { | |
60 | cycle_t interval; | |
61 | u64 tmp; | |
62 | ||
63 | timekeeper.clock = clock; | |
64 | clock->cycle_last = clock->read(clock); | |
65 | ||
66 | /* Do the ns -> cycle conversion first, using original mult */ | |
67 | tmp = NTP_INTERVAL_LENGTH; | |
68 | tmp <<= clock->shift; | |
69 | tmp += clock->mult_orig/2; | |
70 | do_div(tmp, clock->mult_orig); | |
71 | if (tmp == 0) | |
72 | tmp = 1; | |
73 | ||
74 | interval = (cycle_t) tmp; | |
75 | timekeeper.cycle_interval = interval; | |
76 | ||
77 | /* Go back from cycles -> shifted ns */ | |
78 | timekeeper.xtime_interval = (u64) interval * clock->mult; | |
79 | timekeeper.raw_interval = | |
80 | ((u64) interval * clock->mult_orig) >> clock->shift; | |
81 | ||
82 | timekeeper.xtime_nsec = 0; | |
23ce7211 | 83 | timekeeper.shift = clock->shift; |
155ec602 MS |
84 | |
85 | timekeeper.ntp_error = 0; | |
23ce7211 | 86 | timekeeper.ntp_error_shift = NTP_SCALE_SHIFT - clock->shift; |
155ec602 | 87 | } |
8524070b JS |
88 | |
89 | /* | |
90 | * This read-write spinlock protects us from races in SMP while | |
dce48a84 | 91 | * playing with xtime. |
8524070b | 92 | */ |
ba2a631b | 93 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock); |
8524070b JS |
94 | |
95 | ||
96 | /* | |
97 | * The current time | |
98 | * wall_to_monotonic is what we need to add to xtime (or xtime corrected | |
99 | * for sub jiffie times) to get to monotonic time. Monotonic is pegged | |
100 | * at zero at system boot time, so wall_to_monotonic will be negative, | |
101 | * however, we will ALWAYS keep the tv_nsec part positive so we can use | |
102 | * the usual normalization. | |
7c3f1a57 TJ |
103 | * |
104 | * wall_to_monotonic is moved after resume from suspend for the monotonic | |
105 | * time not to jump. We need to add total_sleep_time to wall_to_monotonic | |
106 | * to get the real boot based time offset. | |
107 | * | |
108 | * - wall_to_monotonic is no longer the boot time, getboottime must be | |
109 | * used instead. | |
8524070b JS |
110 | */ |
111 | struct timespec xtime __attribute__ ((aligned (16))); | |
112 | struct timespec wall_to_monotonic __attribute__ ((aligned (16))); | |
7c3f1a57 | 113 | static unsigned long total_sleep_time; /* seconds */ |
8524070b | 114 | |
155ec602 MS |
115 | /* |
116 | * The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. | |
117 | */ | |
118 | struct timespec raw_time; | |
119 | ||
1c5745aa TG |
120 | /* flag for if timekeeping is suspended */ |
121 | int __read_mostly timekeeping_suspended; | |
122 | ||
17c38b74 | 123 | static struct timespec xtime_cache __attribute__ ((aligned (16))); |
1001d0a9 | 124 | void update_xtime_cache(u64 nsec) |
17c38b74 JS |
125 | { |
126 | xtime_cache = xtime; | |
127 | timespec_add_ns(&xtime_cache, nsec); | |
128 | } | |
17c38b74 | 129 | |
31089c13 JS |
130 | /* must hold xtime_lock */ |
131 | void timekeeping_leap_insert(int leapsecond) | |
132 | { | |
133 | xtime.tv_sec += leapsecond; | |
134 | wall_to_monotonic.tv_sec -= leapsecond; | |
155ec602 | 135 | update_vsyscall(&xtime, timekeeper.clock); |
31089c13 | 136 | } |
8524070b JS |
137 | |
138 | #ifdef CONFIG_GENERIC_TIME | |
139 | /** | |
155ec602 | 140 | * timekeeping_forward_now - update clock to the current time |
8524070b | 141 | * |
9a055117 RZ |
142 | * Forward the current clock to update its state since the last call to |
143 | * update_wall_time(). This is useful before significant clock changes, | |
144 | * as it avoids having to deal with this time offset explicitly. | |
8524070b | 145 | */ |
155ec602 | 146 | static void timekeeping_forward_now(void) |
8524070b JS |
147 | { |
148 | cycle_t cycle_now, cycle_delta; | |
155ec602 | 149 | struct clocksource *clock; |
9a055117 | 150 | s64 nsec; |
8524070b | 151 | |
155ec602 | 152 | clock = timekeeper.clock; |
a0f7d48b | 153 | cycle_now = clock->read(clock); |
8524070b | 154 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; |
9a055117 | 155 | clock->cycle_last = cycle_now; |
8524070b | 156 | |
155ec602 | 157 | nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift); |
7d27558c JS |
158 | |
159 | /* If arch requires, add in gettimeoffset() */ | |
160 | nsec += arch_gettimeoffset(); | |
161 | ||
9a055117 | 162 | timespec_add_ns(&xtime, nsec); |
2d42244a | 163 | |
155ec602 MS |
164 | nsec = clocksource_cyc2ns(cycle_delta, clock->mult_orig, clock->shift); |
165 | timespec_add_ns(&raw_time, nsec); | |
8524070b JS |
166 | } |
167 | ||
168 | /** | |
efd9ac86 | 169 | * getnstimeofday - Returns the time of day in a timespec |
8524070b JS |
170 | * @ts: pointer to the timespec to be set |
171 | * | |
efd9ac86 | 172 | * Returns the time of day in a timespec. |
8524070b | 173 | */ |
efd9ac86 | 174 | void getnstimeofday(struct timespec *ts) |
8524070b | 175 | { |
9a055117 | 176 | cycle_t cycle_now, cycle_delta; |
155ec602 | 177 | struct clocksource *clock; |
8524070b JS |
178 | unsigned long seq; |
179 | s64 nsecs; | |
180 | ||
1c5745aa TG |
181 | WARN_ON(timekeeping_suspended); |
182 | ||
8524070b JS |
183 | do { |
184 | seq = read_seqbegin(&xtime_lock); | |
185 | ||
186 | *ts = xtime; | |
9a055117 RZ |
187 | |
188 | /* read clocksource: */ | |
155ec602 | 189 | clock = timekeeper.clock; |
a0f7d48b | 190 | cycle_now = clock->read(clock); |
9a055117 RZ |
191 | |
192 | /* calculate the delta since the last update_wall_time: */ | |
193 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; | |
194 | ||
195 | /* convert to nanoseconds: */ | |
155ec602 MS |
196 | nsecs = clocksource_cyc2ns(cycle_delta, clock->mult, |
197 | clock->shift); | |
8524070b | 198 | |
7d27558c JS |
199 | /* If arch requires, add in gettimeoffset() */ |
200 | nsecs += arch_gettimeoffset(); | |
201 | ||
8524070b JS |
202 | } while (read_seqretry(&xtime_lock, seq)); |
203 | ||
204 | timespec_add_ns(ts, nsecs); | |
205 | } | |
206 | ||
8524070b JS |
207 | EXPORT_SYMBOL(getnstimeofday); |
208 | ||
951ed4d3 MS |
209 | ktime_t ktime_get(void) |
210 | { | |
211 | cycle_t cycle_now, cycle_delta; | |
155ec602 | 212 | struct clocksource *clock; |
951ed4d3 MS |
213 | unsigned int seq; |
214 | s64 secs, nsecs; | |
215 | ||
216 | WARN_ON(timekeeping_suspended); | |
217 | ||
218 | do { | |
219 | seq = read_seqbegin(&xtime_lock); | |
220 | secs = xtime.tv_sec + wall_to_monotonic.tv_sec; | |
221 | nsecs = xtime.tv_nsec + wall_to_monotonic.tv_nsec; | |
222 | ||
223 | /* read clocksource: */ | |
155ec602 | 224 | clock = timekeeper.clock; |
a0f7d48b | 225 | cycle_now = clock->read(clock); |
951ed4d3 MS |
226 | |
227 | /* calculate the delta since the last update_wall_time: */ | |
228 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; | |
229 | ||
230 | /* convert to nanoseconds: */ | |
155ec602 MS |
231 | nsecs += clocksource_cyc2ns(cycle_delta, clock->mult, |
232 | clock->shift); | |
951ed4d3 MS |
233 | |
234 | } while (read_seqretry(&xtime_lock, seq)); | |
235 | /* | |
236 | * Use ktime_set/ktime_add_ns to create a proper ktime on | |
237 | * 32-bit architectures without CONFIG_KTIME_SCALAR. | |
238 | */ | |
239 | return ktime_add_ns(ktime_set(secs, 0), nsecs); | |
240 | } | |
241 | EXPORT_SYMBOL_GPL(ktime_get); | |
242 | ||
243 | /** | |
244 | * ktime_get_ts - get the monotonic clock in timespec format | |
245 | * @ts: pointer to timespec variable | |
246 | * | |
247 | * The function calculates the monotonic clock from the realtime | |
248 | * clock and the wall_to_monotonic offset and stores the result | |
249 | * in normalized timespec format in the variable pointed to by @ts. | |
250 | */ | |
251 | void ktime_get_ts(struct timespec *ts) | |
252 | { | |
253 | cycle_t cycle_now, cycle_delta; | |
155ec602 | 254 | struct clocksource *clock; |
951ed4d3 MS |
255 | struct timespec tomono; |
256 | unsigned int seq; | |
257 | s64 nsecs; | |
258 | ||
259 | WARN_ON(timekeeping_suspended); | |
260 | ||
261 | do { | |
262 | seq = read_seqbegin(&xtime_lock); | |
263 | *ts = xtime; | |
264 | tomono = wall_to_monotonic; | |
265 | ||
266 | /* read clocksource: */ | |
155ec602 | 267 | clock = timekeeper.clock; |
a0f7d48b | 268 | cycle_now = clock->read(clock); |
951ed4d3 MS |
269 | |
270 | /* calculate the delta since the last update_wall_time: */ | |
271 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; | |
272 | ||
273 | /* convert to nanoseconds: */ | |
155ec602 MS |
274 | nsecs = clocksource_cyc2ns(cycle_delta, clock->mult, |
275 | clock->shift); | |
951ed4d3 MS |
276 | |
277 | } while (read_seqretry(&xtime_lock, seq)); | |
278 | ||
279 | set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec, | |
280 | ts->tv_nsec + tomono.tv_nsec + nsecs); | |
281 | } | |
282 | EXPORT_SYMBOL_GPL(ktime_get_ts); | |
283 | ||
8524070b JS |
284 | /** |
285 | * do_gettimeofday - Returns the time of day in a timeval | |
286 | * @tv: pointer to the timeval to be set | |
287 | * | |
efd9ac86 | 288 | * NOTE: Users should be converted to using getnstimeofday() |
8524070b JS |
289 | */ |
290 | void do_gettimeofday(struct timeval *tv) | |
291 | { | |
292 | struct timespec now; | |
293 | ||
efd9ac86 | 294 | getnstimeofday(&now); |
8524070b JS |
295 | tv->tv_sec = now.tv_sec; |
296 | tv->tv_usec = now.tv_nsec/1000; | |
297 | } | |
298 | ||
299 | EXPORT_SYMBOL(do_gettimeofday); | |
300 | /** | |
301 | * do_settimeofday - Sets the time of day | |
302 | * @tv: pointer to the timespec variable containing the new time | |
303 | * | |
304 | * Sets the time of day to the new time and update NTP and notify hrtimers | |
305 | */ | |
306 | int do_settimeofday(struct timespec *tv) | |
307 | { | |
9a055117 | 308 | struct timespec ts_delta; |
8524070b | 309 | unsigned long flags; |
8524070b JS |
310 | |
311 | if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) | |
312 | return -EINVAL; | |
313 | ||
314 | write_seqlock_irqsave(&xtime_lock, flags); | |
315 | ||
155ec602 | 316 | timekeeping_forward_now(); |
9a055117 RZ |
317 | |
318 | ts_delta.tv_sec = tv->tv_sec - xtime.tv_sec; | |
319 | ts_delta.tv_nsec = tv->tv_nsec - xtime.tv_nsec; | |
320 | wall_to_monotonic = timespec_sub(wall_to_monotonic, ts_delta); | |
8524070b | 321 | |
9a055117 | 322 | xtime = *tv; |
8524070b | 323 | |
1001d0a9 | 324 | update_xtime_cache(0); |
8524070b | 325 | |
155ec602 | 326 | timekeeper.ntp_error = 0; |
8524070b JS |
327 | ntp_clear(); |
328 | ||
155ec602 | 329 | update_vsyscall(&xtime, timekeeper.clock); |
8524070b JS |
330 | |
331 | write_sequnlock_irqrestore(&xtime_lock, flags); | |
332 | ||
333 | /* signal hrtimers about time change */ | |
334 | clock_was_set(); | |
335 | ||
336 | return 0; | |
337 | } | |
338 | ||
339 | EXPORT_SYMBOL(do_settimeofday); | |
340 | ||
341 | /** | |
342 | * change_clocksource - Swaps clocksources if a new one is available | |
343 | * | |
344 | * Accumulates current time interval and initializes new clocksource | |
345 | */ | |
346 | static void change_clocksource(void) | |
347 | { | |
4614e6ad | 348 | struct clocksource *new, *old; |
8524070b JS |
349 | |
350 | new = clocksource_get_next(); | |
351 | ||
155ec602 | 352 | if (!new || timekeeper.clock == new) |
8524070b JS |
353 | return; |
354 | ||
155ec602 | 355 | timekeeping_forward_now(); |
8524070b | 356 | |
a0f7d48b | 357 | if (new->enable && !new->enable(new)) |
4614e6ad | 358 | return; |
a0f7d48b MS |
359 | /* |
360 | * The frequency may have changed while the clocksource | |
361 | * was disabled. If so the code in ->enable() must update | |
362 | * the mult value to reflect the new frequency. Make sure | |
363 | * mult_orig follows this change. | |
364 | */ | |
365 | new->mult_orig = new->mult; | |
2d42244a | 366 | |
155ec602 MS |
367 | old = timekeeper.clock; |
368 | timekeeper_setup_internals(new); | |
369 | ||
a0f7d48b MS |
370 | /* |
371 | * Save mult_orig in mult so that the value can be restored | |
372 | * regardless if ->enable() updates the value of mult or not. | |
373 | */ | |
374 | old->mult = old->mult_orig; | |
375 | if (old->disable) | |
376 | old->disable(old); | |
4614e6ad | 377 | |
8524070b | 378 | tick_clock_notify(); |
8524070b | 379 | } |
a40f262c | 380 | #else /* GENERIC_TIME */ |
155ec602 | 381 | static inline void timekeeping_forward_now(void) { } |
8524070b | 382 | static inline void change_clocksource(void) { } |
a40f262c TG |
383 | |
384 | /** | |
385 | * ktime_get - get the monotonic time in ktime_t format | |
386 | * | |
387 | * returns the time in ktime_t format | |
388 | */ | |
389 | ktime_t ktime_get(void) | |
390 | { | |
391 | struct timespec now; | |
392 | ||
393 | ktime_get_ts(&now); | |
394 | ||
395 | return timespec_to_ktime(now); | |
396 | } | |
397 | EXPORT_SYMBOL_GPL(ktime_get); | |
398 | ||
399 | /** | |
400 | * ktime_get_ts - get the monotonic clock in timespec format | |
401 | * @ts: pointer to timespec variable | |
402 | * | |
403 | * The function calculates the monotonic clock from the realtime | |
404 | * clock and the wall_to_monotonic offset and stores the result | |
405 | * in normalized timespec format in the variable pointed to by @ts. | |
406 | */ | |
407 | void ktime_get_ts(struct timespec *ts) | |
408 | { | |
409 | struct timespec tomono; | |
410 | unsigned long seq; | |
411 | ||
412 | do { | |
413 | seq = read_seqbegin(&xtime_lock); | |
414 | getnstimeofday(ts); | |
415 | tomono = wall_to_monotonic; | |
416 | ||
417 | } while (read_seqretry(&xtime_lock, seq)); | |
418 | ||
419 | set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec, | |
420 | ts->tv_nsec + tomono.tv_nsec); | |
421 | } | |
422 | EXPORT_SYMBOL_GPL(ktime_get_ts); | |
423 | #endif /* !GENERIC_TIME */ | |
424 | ||
425 | /** | |
426 | * ktime_get_real - get the real (wall-) time in ktime_t format | |
427 | * | |
428 | * returns the time in ktime_t format | |
429 | */ | |
430 | ktime_t ktime_get_real(void) | |
431 | { | |
432 | struct timespec now; | |
433 | ||
434 | getnstimeofday(&now); | |
435 | ||
436 | return timespec_to_ktime(now); | |
437 | } | |
438 | EXPORT_SYMBOL_GPL(ktime_get_real); | |
8524070b | 439 | |
2d42244a JS |
440 | /** |
441 | * getrawmonotonic - Returns the raw monotonic time in a timespec | |
442 | * @ts: pointer to the timespec to be set | |
443 | * | |
444 | * Returns the raw monotonic time (completely un-modified by ntp) | |
445 | */ | |
446 | void getrawmonotonic(struct timespec *ts) | |
447 | { | |
448 | unsigned long seq; | |
449 | s64 nsecs; | |
450 | cycle_t cycle_now, cycle_delta; | |
155ec602 | 451 | struct clocksource *clock; |
2d42244a JS |
452 | |
453 | do { | |
454 | seq = read_seqbegin(&xtime_lock); | |
455 | ||
456 | /* read clocksource: */ | |
155ec602 | 457 | clock = timekeeper.clock; |
a0f7d48b | 458 | cycle_now = clock->read(clock); |
2d42244a JS |
459 | |
460 | /* calculate the delta since the last update_wall_time: */ | |
461 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; | |
462 | ||
463 | /* convert to nanoseconds: */ | |
155ec602 MS |
464 | nsecs = clocksource_cyc2ns(cycle_delta, clock->mult_orig, |
465 | clock->shift); | |
2d42244a | 466 | |
155ec602 | 467 | *ts = raw_time; |
2d42244a JS |
468 | |
469 | } while (read_seqretry(&xtime_lock, seq)); | |
470 | ||
471 | timespec_add_ns(ts, nsecs); | |
472 | } | |
473 | EXPORT_SYMBOL(getrawmonotonic); | |
474 | ||
475 | ||
8524070b | 476 | /** |
cf4fc6cb | 477 | * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres |
8524070b | 478 | */ |
cf4fc6cb | 479 | int timekeeping_valid_for_hres(void) |
8524070b JS |
480 | { |
481 | unsigned long seq; | |
482 | int ret; | |
483 | ||
484 | do { | |
485 | seq = read_seqbegin(&xtime_lock); | |
486 | ||
155ec602 | 487 | ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES; |
8524070b JS |
488 | |
489 | } while (read_seqretry(&xtime_lock, seq)); | |
490 | ||
491 | return ret; | |
492 | } | |
493 | ||
494 | /** | |
495 | * read_persistent_clock - Return time in seconds from the persistent clock. | |
496 | * | |
497 | * Weak dummy function for arches that do not yet support it. | |
498 | * Returns seconds from epoch using the battery backed persistent clock. | |
499 | * Returns zero if unsupported. | |
500 | * | |
501 | * XXX - Do be sure to remove it once all arches implement it. | |
502 | */ | |
503 | unsigned long __attribute__((weak)) read_persistent_clock(void) | |
504 | { | |
505 | return 0; | |
506 | } | |
507 | ||
508 | /* | |
509 | * timekeeping_init - Initializes the clocksource and common timekeeping values | |
510 | */ | |
511 | void __init timekeeping_init(void) | |
512 | { | |
155ec602 | 513 | struct clocksource *clock; |
8524070b JS |
514 | unsigned long flags; |
515 | unsigned long sec = read_persistent_clock(); | |
516 | ||
517 | write_seqlock_irqsave(&xtime_lock, flags); | |
518 | ||
7dffa3c6 | 519 | ntp_init(); |
8524070b | 520 | |
f1b82746 | 521 | clock = clocksource_default_clock(); |
a0f7d48b MS |
522 | if (clock->enable) |
523 | clock->enable(clock); | |
524 | /* set mult_orig on enable */ | |
525 | clock->mult_orig = clock->mult; | |
155ec602 MS |
526 | |
527 | timekeeper_setup_internals(clock); | |
8524070b JS |
528 | |
529 | xtime.tv_sec = sec; | |
530 | xtime.tv_nsec = 0; | |
155ec602 MS |
531 | raw_time.tv_sec = 0; |
532 | raw_time.tv_nsec = 0; | |
8524070b JS |
533 | set_normalized_timespec(&wall_to_monotonic, |
534 | -xtime.tv_sec, -xtime.tv_nsec); | |
1001d0a9 | 535 | update_xtime_cache(0); |
7c3f1a57 | 536 | total_sleep_time = 0; |
8524070b JS |
537 | write_sequnlock_irqrestore(&xtime_lock, flags); |
538 | } | |
539 | ||
8524070b JS |
540 | /* time in seconds when suspend began */ |
541 | static unsigned long timekeeping_suspend_time; | |
542 | ||
543 | /** | |
544 | * timekeeping_resume - Resumes the generic timekeeping subsystem. | |
545 | * @dev: unused | |
546 | * | |
547 | * This is for the generic clocksource timekeeping. | |
548 | * xtime/wall_to_monotonic/jiffies/etc are | |
549 | * still managed by arch specific suspend/resume code. | |
550 | */ | |
551 | static int timekeeping_resume(struct sys_device *dev) | |
552 | { | |
553 | unsigned long flags; | |
554 | unsigned long now = read_persistent_clock(); | |
555 | ||
d10ff3fb TG |
556 | clocksource_resume(); |
557 | ||
8524070b JS |
558 | write_seqlock_irqsave(&xtime_lock, flags); |
559 | ||
560 | if (now && (now > timekeeping_suspend_time)) { | |
561 | unsigned long sleep_length = now - timekeeping_suspend_time; | |
562 | ||
563 | xtime.tv_sec += sleep_length; | |
564 | wall_to_monotonic.tv_sec -= sleep_length; | |
7c3f1a57 | 565 | total_sleep_time += sleep_length; |
8524070b | 566 | } |
1001d0a9 | 567 | update_xtime_cache(0); |
8524070b | 568 | /* re-base the last cycle value */ |
155ec602 MS |
569 | timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock); |
570 | timekeeper.ntp_error = 0; | |
8524070b JS |
571 | timekeeping_suspended = 0; |
572 | write_sequnlock_irqrestore(&xtime_lock, flags); | |
573 | ||
574 | touch_softlockup_watchdog(); | |
575 | ||
576 | clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); | |
577 | ||
578 | /* Resume hrtimers */ | |
579 | hres_timers_resume(); | |
580 | ||
581 | return 0; | |
582 | } | |
583 | ||
584 | static int timekeeping_suspend(struct sys_device *dev, pm_message_t state) | |
585 | { | |
586 | unsigned long flags; | |
587 | ||
3be90950 TG |
588 | timekeeping_suspend_time = read_persistent_clock(); |
589 | ||
8524070b | 590 | write_seqlock_irqsave(&xtime_lock, flags); |
155ec602 | 591 | timekeeping_forward_now(); |
8524070b | 592 | timekeeping_suspended = 1; |
8524070b JS |
593 | write_sequnlock_irqrestore(&xtime_lock, flags); |
594 | ||
595 | clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); | |
596 | ||
597 | return 0; | |
598 | } | |
599 | ||
600 | /* sysfs resume/suspend bits for timekeeping */ | |
601 | static struct sysdev_class timekeeping_sysclass = { | |
af5ca3f4 | 602 | .name = "timekeeping", |
8524070b JS |
603 | .resume = timekeeping_resume, |
604 | .suspend = timekeeping_suspend, | |
8524070b JS |
605 | }; |
606 | ||
607 | static struct sys_device device_timer = { | |
608 | .id = 0, | |
609 | .cls = &timekeeping_sysclass, | |
610 | }; | |
611 | ||
612 | static int __init timekeeping_init_device(void) | |
613 | { | |
614 | int error = sysdev_class_register(&timekeeping_sysclass); | |
615 | if (!error) | |
616 | error = sysdev_register(&device_timer); | |
617 | return error; | |
618 | } | |
619 | ||
620 | device_initcall(timekeeping_init_device); | |
621 | ||
622 | /* | |
623 | * If the error is already larger, we look ahead even further | |
624 | * to compensate for late or lost adjustments. | |
625 | */ | |
155ec602 | 626 | static __always_inline int timekeeping_bigadjust(s64 error, s64 *interval, |
8524070b JS |
627 | s64 *offset) |
628 | { | |
629 | s64 tick_error, i; | |
630 | u32 look_ahead, adj; | |
631 | s32 error2, mult; | |
632 | ||
633 | /* | |
634 | * Use the current error value to determine how much to look ahead. | |
635 | * The larger the error the slower we adjust for it to avoid problems | |
636 | * with losing too many ticks, otherwise we would overadjust and | |
637 | * produce an even larger error. The smaller the adjustment the | |
638 | * faster we try to adjust for it, as lost ticks can do less harm | |
3eb05676 | 639 | * here. This is tuned so that an error of about 1 msec is adjusted |
8524070b JS |
640 | * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks). |
641 | */ | |
155ec602 | 642 | error2 = timekeeper.ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ); |
8524070b JS |
643 | error2 = abs(error2); |
644 | for (look_ahead = 0; error2 > 0; look_ahead++) | |
645 | error2 >>= 2; | |
646 | ||
647 | /* | |
648 | * Now calculate the error in (1 << look_ahead) ticks, but first | |
649 | * remove the single look ahead already included in the error. | |
650 | */ | |
23ce7211 | 651 | tick_error = tick_length >> (timekeeper.ntp_error_shift + 1); |
155ec602 | 652 | tick_error -= timekeeper.xtime_interval >> 1; |
8524070b JS |
653 | error = ((error - tick_error) >> look_ahead) + tick_error; |
654 | ||
655 | /* Finally calculate the adjustment shift value. */ | |
656 | i = *interval; | |
657 | mult = 1; | |
658 | if (error < 0) { | |
659 | error = -error; | |
660 | *interval = -*interval; | |
661 | *offset = -*offset; | |
662 | mult = -1; | |
663 | } | |
664 | for (adj = 0; error > i; adj++) | |
665 | error >>= 1; | |
666 | ||
667 | *interval <<= adj; | |
668 | *offset <<= adj; | |
669 | return mult << adj; | |
670 | } | |
671 | ||
672 | /* | |
673 | * Adjust the multiplier to reduce the error value, | |
674 | * this is optimized for the most common adjustments of -1,0,1, | |
675 | * for other values we can do a bit more work. | |
676 | */ | |
155ec602 | 677 | static void timekeeping_adjust(s64 offset) |
8524070b | 678 | { |
155ec602 | 679 | s64 error, interval = timekeeper.cycle_interval; |
8524070b JS |
680 | int adj; |
681 | ||
23ce7211 | 682 | error = timekeeper.ntp_error >> (timekeeper.ntp_error_shift - 1); |
8524070b JS |
683 | if (error > interval) { |
684 | error >>= 2; | |
685 | if (likely(error <= interval)) | |
686 | adj = 1; | |
687 | else | |
155ec602 | 688 | adj = timekeeping_bigadjust(error, &interval, &offset); |
8524070b JS |
689 | } else if (error < -interval) { |
690 | error >>= 2; | |
691 | if (likely(error >= -interval)) { | |
692 | adj = -1; | |
693 | interval = -interval; | |
694 | offset = -offset; | |
695 | } else | |
155ec602 | 696 | adj = timekeeping_bigadjust(error, &interval, &offset); |
8524070b JS |
697 | } else |
698 | return; | |
699 | ||
155ec602 MS |
700 | timekeeper.clock->mult += adj; |
701 | timekeeper.xtime_interval += interval; | |
702 | timekeeper.xtime_nsec -= offset; | |
703 | timekeeper.ntp_error -= (interval - offset) << | |
23ce7211 | 704 | timekeeper.ntp_error_shift; |
8524070b JS |
705 | } |
706 | ||
707 | /** | |
708 | * update_wall_time - Uses the current clocksource to increment the wall time | |
709 | * | |
710 | * Called from the timer interrupt, must hold a write on xtime_lock. | |
711 | */ | |
712 | void update_wall_time(void) | |
713 | { | |
155ec602 | 714 | struct clocksource *clock; |
8524070b | 715 | cycle_t offset; |
23ce7211 | 716 | u64 nsecs; |
8524070b JS |
717 | |
718 | /* Make sure we're fully resumed: */ | |
719 | if (unlikely(timekeeping_suspended)) | |
720 | return; | |
721 | ||
155ec602 | 722 | clock = timekeeper.clock; |
8524070b | 723 | #ifdef CONFIG_GENERIC_TIME |
a0f7d48b | 724 | offset = (clock->read(clock) - clock->cycle_last) & clock->mask; |
8524070b | 725 | #else |
155ec602 | 726 | offset = timekeeper.cycle_interval; |
8524070b | 727 | #endif |
23ce7211 | 728 | timekeeper.xtime_nsec = (s64)xtime.tv_nsec << timekeeper.shift; |
8524070b JS |
729 | |
730 | /* normally this loop will run just once, however in the | |
731 | * case of lost or late ticks, it will accumulate correctly. | |
732 | */ | |
155ec602 | 733 | while (offset >= timekeeper.cycle_interval) { |
23ce7211 | 734 | u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift; |
155ec602 | 735 | |
8524070b | 736 | /* accumulate one interval */ |
155ec602 MS |
737 | offset -= timekeeper.cycle_interval; |
738 | clock->cycle_last += timekeeper.cycle_interval; | |
8524070b | 739 | |
155ec602 MS |
740 | timekeeper.xtime_nsec += timekeeper.xtime_interval; |
741 | if (timekeeper.xtime_nsec >= nsecps) { | |
742 | timekeeper.xtime_nsec -= nsecps; | |
8524070b JS |
743 | xtime.tv_sec++; |
744 | second_overflow(); | |
745 | } | |
746 | ||
155ec602 MS |
747 | raw_time.tv_nsec += timekeeper.raw_interval; |
748 | if (raw_time.tv_nsec >= NSEC_PER_SEC) { | |
749 | raw_time.tv_nsec -= NSEC_PER_SEC; | |
750 | raw_time.tv_sec++; | |
2d42244a JS |
751 | } |
752 | ||
8524070b | 753 | /* accumulate error between NTP and clock interval */ |
155ec602 MS |
754 | timekeeper.ntp_error += tick_length; |
755 | timekeeper.ntp_error -= timekeeper.xtime_interval << | |
23ce7211 | 756 | timekeeper.ntp_error_shift; |
8524070b JS |
757 | } |
758 | ||
759 | /* correct the clock when NTP error is too big */ | |
155ec602 | 760 | timekeeping_adjust(offset); |
8524070b | 761 | |
6c9bacb4 JS |
762 | /* |
763 | * Since in the loop above, we accumulate any amount of time | |
764 | * in xtime_nsec over a second into xtime.tv_sec, its possible for | |
765 | * xtime_nsec to be fairly small after the loop. Further, if we're | |
155ec602 | 766 | * slightly speeding the clocksource up in timekeeping_adjust(), |
6c9bacb4 JS |
767 | * its possible the required corrective factor to xtime_nsec could |
768 | * cause it to underflow. | |
769 | * | |
770 | * Now, we cannot simply roll the accumulated second back, since | |
771 | * the NTP subsystem has been notified via second_overflow. So | |
772 | * instead we push xtime_nsec forward by the amount we underflowed, | |
773 | * and add that amount into the error. | |
774 | * | |
775 | * We'll correct this error next time through this function, when | |
776 | * xtime_nsec is not as small. | |
777 | */ | |
155ec602 MS |
778 | if (unlikely((s64)timekeeper.xtime_nsec < 0)) { |
779 | s64 neg = -(s64)timekeeper.xtime_nsec; | |
780 | timekeeper.xtime_nsec = 0; | |
23ce7211 | 781 | timekeeper.ntp_error += neg << timekeeper.ntp_error_shift; |
6c9bacb4 JS |
782 | } |
783 | ||
5cd1c9c5 RZ |
784 | /* store full nanoseconds into xtime after rounding it up and |
785 | * add the remainder to the error difference. | |
786 | */ | |
23ce7211 MS |
787 | xtime.tv_nsec = ((s64) timekeeper.xtime_nsec >> timekeeper.shift) + 1; |
788 | timekeeper.xtime_nsec -= (s64) xtime.tv_nsec << timekeeper.shift; | |
789 | timekeeper.ntp_error += timekeeper.xtime_nsec << | |
790 | timekeeper.ntp_error_shift; | |
8524070b | 791 | |
155ec602 MS |
792 | nsecs = clocksource_cyc2ns(offset, clock->mult, clock->shift); |
793 | update_xtime_cache(nsecs); | |
17c38b74 | 794 | |
8524070b JS |
795 | /* check to see if there is a new clocksource to use */ |
796 | change_clocksource(); | |
155ec602 | 797 | update_vsyscall(&xtime, timekeeper.clock); |
8524070b | 798 | } |
7c3f1a57 TJ |
799 | |
800 | /** | |
801 | * getboottime - Return the real time of system boot. | |
802 | * @ts: pointer to the timespec to be set | |
803 | * | |
804 | * Returns the time of day in a timespec. | |
805 | * | |
806 | * This is based on the wall_to_monotonic offset and the total suspend | |
807 | * time. Calls to settimeofday will affect the value returned (which | |
808 | * basically means that however wrong your real time clock is at boot time, | |
809 | * you get the right time here). | |
810 | */ | |
811 | void getboottime(struct timespec *ts) | |
812 | { | |
813 | set_normalized_timespec(ts, | |
814 | - (wall_to_monotonic.tv_sec + total_sleep_time), | |
815 | - wall_to_monotonic.tv_nsec); | |
816 | } | |
817 | ||
818 | /** | |
819 | * monotonic_to_bootbased - Convert the monotonic time to boot based. | |
820 | * @ts: pointer to the timespec to be converted | |
821 | */ | |
822 | void monotonic_to_bootbased(struct timespec *ts) | |
823 | { | |
824 | ts->tv_sec += total_sleep_time; | |
825 | } | |
2c6b47de | 826 | |
17c38b74 JS |
827 | unsigned long get_seconds(void) |
828 | { | |
829 | return xtime_cache.tv_sec; | |
830 | } | |
831 | EXPORT_SYMBOL(get_seconds); | |
832 | ||
833 | ||
2c6b47de JS |
834 | struct timespec current_kernel_time(void) |
835 | { | |
836 | struct timespec now; | |
837 | unsigned long seq; | |
838 | ||
839 | do { | |
840 | seq = read_seqbegin(&xtime_lock); | |
841 | ||
17c38b74 | 842 | now = xtime_cache; |
2c6b47de JS |
843 | } while (read_seqretry(&xtime_lock, seq)); |
844 | ||
845 | return now; | |
846 | } | |
2c6b47de | 847 | EXPORT_SYMBOL(current_kernel_time); |