Commit | Line | Data |
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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> | |
75c5158f | 21 | #include <linux/stop_machine.h> |
8524070b | 22 | |
155ec602 MS |
23 | /* Structure holding internal timekeeping values. */ |
24 | struct timekeeper { | |
25 | /* Current clocksource used for timekeeping. */ | |
26 | struct clocksource *clock; | |
23ce7211 MS |
27 | /* The shift value of the current clocksource. */ |
28 | int shift; | |
155ec602 MS |
29 | |
30 | /* Number of clock cycles in one NTP interval. */ | |
31 | cycle_t cycle_interval; | |
32 | /* Number of clock shifted nano seconds in one NTP interval. */ | |
33 | u64 xtime_interval; | |
34 | /* Raw nano seconds accumulated per NTP interval. */ | |
35 | u32 raw_interval; | |
36 | ||
37 | /* Clock shifted nano seconds remainder not stored in xtime.tv_nsec. */ | |
38 | u64 xtime_nsec; | |
39 | /* Difference between accumulated time and NTP time in ntp | |
40 | * shifted nano seconds. */ | |
41 | s64 ntp_error; | |
23ce7211 MS |
42 | /* Shift conversion between clock shifted nano seconds and |
43 | * ntp shifted nano seconds. */ | |
44 | int ntp_error_shift; | |
0a544198 MS |
45 | /* NTP adjusted clock multiplier */ |
46 | u32 mult; | |
155ec602 MS |
47 | }; |
48 | ||
49 | struct timekeeper timekeeper; | |
50 | ||
51 | /** | |
52 | * timekeeper_setup_internals - Set up internals to use clocksource clock. | |
53 | * | |
54 | * @clock: Pointer to clocksource. | |
55 | * | |
56 | * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment | |
57 | * pair and interval request. | |
58 | * | |
59 | * Unless you're the timekeeping code, you should not be using this! | |
60 | */ | |
61 | static void timekeeper_setup_internals(struct clocksource *clock) | |
62 | { | |
63 | cycle_t interval; | |
64 | u64 tmp; | |
65 | ||
66 | timekeeper.clock = clock; | |
67 | clock->cycle_last = clock->read(clock); | |
68 | ||
69 | /* Do the ns -> cycle conversion first, using original mult */ | |
70 | tmp = NTP_INTERVAL_LENGTH; | |
71 | tmp <<= clock->shift; | |
0a544198 MS |
72 | tmp += clock->mult/2; |
73 | do_div(tmp, clock->mult); | |
155ec602 MS |
74 | if (tmp == 0) |
75 | tmp = 1; | |
76 | ||
77 | interval = (cycle_t) tmp; | |
78 | timekeeper.cycle_interval = interval; | |
79 | ||
80 | /* Go back from cycles -> shifted ns */ | |
81 | timekeeper.xtime_interval = (u64) interval * clock->mult; | |
82 | timekeeper.raw_interval = | |
0a544198 | 83 | ((u64) interval * clock->mult) >> clock->shift; |
155ec602 MS |
84 | |
85 | timekeeper.xtime_nsec = 0; | |
23ce7211 | 86 | timekeeper.shift = clock->shift; |
155ec602 MS |
87 | |
88 | timekeeper.ntp_error = 0; | |
23ce7211 | 89 | timekeeper.ntp_error_shift = NTP_SCALE_SHIFT - clock->shift; |
0a544198 MS |
90 | |
91 | /* | |
92 | * The timekeeper keeps its own mult values for the currently | |
93 | * active clocksource. These value will be adjusted via NTP | |
94 | * to counteract clock drifting. | |
95 | */ | |
96 | timekeeper.mult = clock->mult; | |
155ec602 | 97 | } |
8524070b | 98 | |
2ba2a305 MS |
99 | /* Timekeeper helper functions. */ |
100 | static inline s64 timekeeping_get_ns(void) | |
101 | { | |
102 | cycle_t cycle_now, cycle_delta; | |
103 | struct clocksource *clock; | |
104 | ||
105 | /* read clocksource: */ | |
106 | clock = timekeeper.clock; | |
107 | cycle_now = clock->read(clock); | |
108 | ||
109 | /* calculate the delta since the last update_wall_time: */ | |
110 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; | |
111 | ||
112 | /* return delta convert to nanoseconds using ntp adjusted mult. */ | |
113 | return clocksource_cyc2ns(cycle_delta, timekeeper.mult, | |
114 | timekeeper.shift); | |
115 | } | |
116 | ||
117 | static inline s64 timekeeping_get_ns_raw(void) | |
118 | { | |
119 | cycle_t cycle_now, cycle_delta; | |
120 | struct clocksource *clock; | |
121 | ||
122 | /* read clocksource: */ | |
123 | clock = timekeeper.clock; | |
124 | cycle_now = clock->read(clock); | |
125 | ||
126 | /* calculate the delta since the last update_wall_time: */ | |
127 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; | |
128 | ||
129 | /* return delta convert to nanoseconds using ntp adjusted mult. */ | |
130 | return clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift); | |
131 | } | |
132 | ||
8524070b | 133 | /* |
134 | * This read-write spinlock protects us from races in SMP while | |
dce48a84 | 135 | * playing with xtime. |
8524070b | 136 | */ |
ba2a631b | 137 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock); |
8524070b | 138 | |
139 | ||
140 | /* | |
141 | * The current time | |
142 | * wall_to_monotonic is what we need to add to xtime (or xtime corrected | |
143 | * for sub jiffie times) to get to monotonic time. Monotonic is pegged | |
144 | * at zero at system boot time, so wall_to_monotonic will be negative, | |
145 | * however, we will ALWAYS keep the tv_nsec part positive so we can use | |
146 | * the usual normalization. | |
7c3f1a57 TJ |
147 | * |
148 | * wall_to_monotonic is moved after resume from suspend for the monotonic | |
149 | * time not to jump. We need to add total_sleep_time to wall_to_monotonic | |
150 | * to get the real boot based time offset. | |
151 | * | |
152 | * - wall_to_monotonic is no longer the boot time, getboottime must be | |
153 | * used instead. | |
8524070b | 154 | */ |
155 | struct timespec xtime __attribute__ ((aligned (16))); | |
156 | struct timespec wall_to_monotonic __attribute__ ((aligned (16))); | |
d4f587c6 | 157 | static struct timespec total_sleep_time; |
8524070b | 158 | |
155ec602 MS |
159 | /* |
160 | * The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. | |
161 | */ | |
162 | struct timespec raw_time; | |
163 | ||
1c5745aa TG |
164 | /* flag for if timekeeping is suspended */ |
165 | int __read_mostly timekeeping_suspended; | |
166 | ||
31089c13 JS |
167 | /* must hold xtime_lock */ |
168 | void timekeeping_leap_insert(int leapsecond) | |
169 | { | |
170 | xtime.tv_sec += leapsecond; | |
171 | wall_to_monotonic.tv_sec -= leapsecond; | |
155ec602 | 172 | update_vsyscall(&xtime, timekeeper.clock); |
31089c13 | 173 | } |
8524070b | 174 | |
175 | #ifdef CONFIG_GENERIC_TIME | |
75c5158f | 176 | |
8524070b | 177 | /** |
155ec602 | 178 | * timekeeping_forward_now - update clock to the current time |
8524070b | 179 | * |
9a055117 RZ |
180 | * Forward the current clock to update its state since the last call to |
181 | * update_wall_time(). This is useful before significant clock changes, | |
182 | * as it avoids having to deal with this time offset explicitly. | |
8524070b | 183 | */ |
155ec602 | 184 | static void timekeeping_forward_now(void) |
8524070b | 185 | { |
186 | cycle_t cycle_now, cycle_delta; | |
155ec602 | 187 | struct clocksource *clock; |
9a055117 | 188 | s64 nsec; |
8524070b | 189 | |
155ec602 | 190 | clock = timekeeper.clock; |
a0f7d48b | 191 | cycle_now = clock->read(clock); |
8524070b | 192 | cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; |
9a055117 | 193 | clock->cycle_last = cycle_now; |
8524070b | 194 | |
0a544198 MS |
195 | nsec = clocksource_cyc2ns(cycle_delta, timekeeper.mult, |
196 | timekeeper.shift); | |
7d27558c | 197 | |
198 | /* If arch requires, add in gettimeoffset() */ | |
199 | nsec += arch_gettimeoffset(); | |
200 | ||
9a055117 | 201 | timespec_add_ns(&xtime, nsec); |
2d42244a | 202 | |
0a544198 | 203 | nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift); |
155ec602 | 204 | timespec_add_ns(&raw_time, nsec); |
8524070b | 205 | } |
206 | ||
207 | /** | |
efd9ac86 | 208 | * getnstimeofday - Returns the time of day in a timespec |
8524070b | 209 | * @ts: pointer to the timespec to be set |
210 | * | |
efd9ac86 | 211 | * Returns the time of day in a timespec. |
8524070b | 212 | */ |
efd9ac86 | 213 | void getnstimeofday(struct timespec *ts) |
8524070b | 214 | { |
215 | unsigned long seq; | |
216 | s64 nsecs; | |
217 | ||
1c5745aa TG |
218 | WARN_ON(timekeeping_suspended); |
219 | ||
8524070b | 220 | do { |
221 | seq = read_seqbegin(&xtime_lock); | |
222 | ||
223 | *ts = xtime; | |
2ba2a305 | 224 | nsecs = timekeeping_get_ns(); |
8524070b | 225 | |
7d27558c | 226 | /* If arch requires, add in gettimeoffset() */ |
227 | nsecs += arch_gettimeoffset(); | |
228 | ||
8524070b | 229 | } while (read_seqretry(&xtime_lock, seq)); |
230 | ||
231 | timespec_add_ns(ts, nsecs); | |
232 | } | |
233 | ||
8524070b | 234 | EXPORT_SYMBOL(getnstimeofday); |
235 | ||
951ed4d3 MS |
236 | ktime_t ktime_get(void) |
237 | { | |
951ed4d3 MS |
238 | unsigned int seq; |
239 | s64 secs, nsecs; | |
240 | ||
241 | WARN_ON(timekeeping_suspended); | |
242 | ||
243 | do { | |
244 | seq = read_seqbegin(&xtime_lock); | |
245 | secs = xtime.tv_sec + wall_to_monotonic.tv_sec; | |
246 | nsecs = xtime.tv_nsec + wall_to_monotonic.tv_nsec; | |
2ba2a305 | 247 | nsecs += timekeeping_get_ns(); |
951ed4d3 MS |
248 | |
249 | } while (read_seqretry(&xtime_lock, seq)); | |
250 | /* | |
251 | * Use ktime_set/ktime_add_ns to create a proper ktime on | |
252 | * 32-bit architectures without CONFIG_KTIME_SCALAR. | |
253 | */ | |
254 | return ktime_add_ns(ktime_set(secs, 0), nsecs); | |
255 | } | |
256 | EXPORT_SYMBOL_GPL(ktime_get); | |
257 | ||
258 | /** | |
259 | * ktime_get_ts - get the monotonic clock in timespec format | |
260 | * @ts: pointer to timespec variable | |
261 | * | |
262 | * The function calculates the monotonic clock from the realtime | |
263 | * clock and the wall_to_monotonic offset and stores the result | |
264 | * in normalized timespec format in the variable pointed to by @ts. | |
265 | */ | |
266 | void ktime_get_ts(struct timespec *ts) | |
267 | { | |
951ed4d3 MS |
268 | struct timespec tomono; |
269 | unsigned int seq; | |
270 | s64 nsecs; | |
271 | ||
272 | WARN_ON(timekeeping_suspended); | |
273 | ||
274 | do { | |
275 | seq = read_seqbegin(&xtime_lock); | |
276 | *ts = xtime; | |
277 | tomono = wall_to_monotonic; | |
2ba2a305 | 278 | nsecs = timekeeping_get_ns(); |
951ed4d3 MS |
279 | |
280 | } while (read_seqretry(&xtime_lock, seq)); | |
281 | ||
282 | set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec, | |
283 | ts->tv_nsec + tomono.tv_nsec + nsecs); | |
284 | } | |
285 | EXPORT_SYMBOL_GPL(ktime_get_ts); | |
286 | ||
8524070b | 287 | /** |
288 | * do_gettimeofday - Returns the time of day in a timeval | |
289 | * @tv: pointer to the timeval to be set | |
290 | * | |
efd9ac86 | 291 | * NOTE: Users should be converted to using getnstimeofday() |
8524070b | 292 | */ |
293 | void do_gettimeofday(struct timeval *tv) | |
294 | { | |
295 | struct timespec now; | |
296 | ||
efd9ac86 | 297 | getnstimeofday(&now); |
8524070b | 298 | tv->tv_sec = now.tv_sec; |
299 | tv->tv_usec = now.tv_nsec/1000; | |
300 | } | |
301 | ||
302 | EXPORT_SYMBOL(do_gettimeofday); | |
303 | /** | |
304 | * do_settimeofday - Sets the time of day | |
305 | * @tv: pointer to the timespec variable containing the new time | |
306 | * | |
307 | * Sets the time of day to the new time and update NTP and notify hrtimers | |
308 | */ | |
309 | int do_settimeofday(struct timespec *tv) | |
310 | { | |
9a055117 | 311 | struct timespec ts_delta; |
8524070b | 312 | unsigned long flags; |
8524070b | 313 | |
314 | if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) | |
315 | return -EINVAL; | |
316 | ||
317 | write_seqlock_irqsave(&xtime_lock, flags); | |
318 | ||
155ec602 | 319 | timekeeping_forward_now(); |
9a055117 RZ |
320 | |
321 | ts_delta.tv_sec = tv->tv_sec - xtime.tv_sec; | |
322 | ts_delta.tv_nsec = tv->tv_nsec - xtime.tv_nsec; | |
323 | wall_to_monotonic = timespec_sub(wall_to_monotonic, ts_delta); | |
8524070b | 324 | |
9a055117 | 325 | xtime = *tv; |
8524070b | 326 | |
155ec602 | 327 | timekeeper.ntp_error = 0; |
8524070b | 328 | ntp_clear(); |
329 | ||
155ec602 | 330 | update_vsyscall(&xtime, timekeeper.clock); |
8524070b | 331 | |
332 | write_sequnlock_irqrestore(&xtime_lock, flags); | |
333 | ||
334 | /* signal hrtimers about time change */ | |
335 | clock_was_set(); | |
336 | ||
337 | return 0; | |
338 | } | |
339 | ||
340 | EXPORT_SYMBOL(do_settimeofday); | |
341 | ||
342 | /** | |
343 | * change_clocksource - Swaps clocksources if a new one is available | |
344 | * | |
345 | * Accumulates current time interval and initializes new clocksource | |
346 | */ | |
75c5158f | 347 | static int change_clocksource(void *data) |
8524070b | 348 | { |
4614e6ad | 349 | struct clocksource *new, *old; |
8524070b | 350 | |
75c5158f | 351 | new = (struct clocksource *) data; |
8524070b | 352 | |
155ec602 | 353 | timekeeping_forward_now(); |
75c5158f MS |
354 | if (!new->enable || new->enable(new) == 0) { |
355 | old = timekeeper.clock; | |
356 | timekeeper_setup_internals(new); | |
357 | if (old->disable) | |
358 | old->disable(old); | |
359 | } | |
360 | return 0; | |
361 | } | |
8524070b | 362 | |
75c5158f MS |
363 | /** |
364 | * timekeeping_notify - Install a new clock source | |
365 | * @clock: pointer to the clock source | |
366 | * | |
367 | * This function is called from clocksource.c after a new, better clock | |
368 | * source has been registered. The caller holds the clocksource_mutex. | |
369 | */ | |
370 | void timekeeping_notify(struct clocksource *clock) | |
371 | { | |
372 | if (timekeeper.clock == clock) | |
4614e6ad | 373 | return; |
75c5158f | 374 | stop_machine(change_clocksource, clock, NULL); |
8524070b | 375 | tick_clock_notify(); |
8524070b | 376 | } |
75c5158f | 377 | |
a40f262c | 378 | #else /* GENERIC_TIME */ |
75c5158f | 379 | |
155ec602 | 380 | static inline void timekeeping_forward_now(void) { } |
a40f262c TG |
381 | |
382 | /** | |
383 | * ktime_get - get the monotonic time in ktime_t format | |
384 | * | |
385 | * returns the time in ktime_t format | |
386 | */ | |
387 | ktime_t ktime_get(void) | |
388 | { | |
389 | struct timespec now; | |
390 | ||
391 | ktime_get_ts(&now); | |
392 | ||
393 | return timespec_to_ktime(now); | |
394 | } | |
395 | EXPORT_SYMBOL_GPL(ktime_get); | |
396 | ||
397 | /** | |
398 | * ktime_get_ts - get the monotonic clock in timespec format | |
399 | * @ts: pointer to timespec variable | |
400 | * | |
401 | * The function calculates the monotonic clock from the realtime | |
402 | * clock and the wall_to_monotonic offset and stores the result | |
403 | * in normalized timespec format in the variable pointed to by @ts. | |
404 | */ | |
405 | void ktime_get_ts(struct timespec *ts) | |
406 | { | |
407 | struct timespec tomono; | |
408 | unsigned long seq; | |
409 | ||
410 | do { | |
411 | seq = read_seqbegin(&xtime_lock); | |
412 | getnstimeofday(ts); | |
413 | tomono = wall_to_monotonic; | |
414 | ||
415 | } while (read_seqretry(&xtime_lock, seq)); | |
416 | ||
417 | set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec, | |
418 | ts->tv_nsec + tomono.tv_nsec); | |
419 | } | |
420 | EXPORT_SYMBOL_GPL(ktime_get_ts); | |
75c5158f | 421 | |
a40f262c TG |
422 | #endif /* !GENERIC_TIME */ |
423 | ||
424 | /** | |
425 | * ktime_get_real - get the real (wall-) time in ktime_t format | |
426 | * | |
427 | * returns the time in ktime_t format | |
428 | */ | |
429 | ktime_t ktime_get_real(void) | |
430 | { | |
431 | struct timespec now; | |
432 | ||
433 | getnstimeofday(&now); | |
434 | ||
435 | return timespec_to_ktime(now); | |
436 | } | |
437 | EXPORT_SYMBOL_GPL(ktime_get_real); | |
8524070b | 438 | |
2d42244a JS |
439 | /** |
440 | * getrawmonotonic - Returns the raw monotonic time in a timespec | |
441 | * @ts: pointer to the timespec to be set | |
442 | * | |
443 | * Returns the raw monotonic time (completely un-modified by ntp) | |
444 | */ | |
445 | void getrawmonotonic(struct timespec *ts) | |
446 | { | |
447 | unsigned long seq; | |
448 | s64 nsecs; | |
2d42244a JS |
449 | |
450 | do { | |
451 | seq = read_seqbegin(&xtime_lock); | |
2ba2a305 | 452 | nsecs = timekeeping_get_ns_raw(); |
155ec602 | 453 | *ts = raw_time; |
2d42244a JS |
454 | |
455 | } while (read_seqretry(&xtime_lock, seq)); | |
456 | ||
457 | timespec_add_ns(ts, nsecs); | |
458 | } | |
459 | EXPORT_SYMBOL(getrawmonotonic); | |
460 | ||
461 | ||
8524070b | 462 | /** |
cf4fc6cb | 463 | * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres |
8524070b | 464 | */ |
cf4fc6cb | 465 | int timekeeping_valid_for_hres(void) |
8524070b | 466 | { |
467 | unsigned long seq; | |
468 | int ret; | |
469 | ||
470 | do { | |
471 | seq = read_seqbegin(&xtime_lock); | |
472 | ||
155ec602 | 473 | ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES; |
8524070b | 474 | |
475 | } while (read_seqretry(&xtime_lock, seq)); | |
476 | ||
477 | return ret; | |
478 | } | |
479 | ||
480 | /** | |
d4f587c6 | 481 | * read_persistent_clock - Return time from the persistent clock. |
8524070b | 482 | * |
483 | * Weak dummy function for arches that do not yet support it. | |
d4f587c6 MS |
484 | * Reads the time from the battery backed persistent clock. |
485 | * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported. | |
8524070b | 486 | * |
487 | * XXX - Do be sure to remove it once all arches implement it. | |
488 | */ | |
d4f587c6 | 489 | void __attribute__((weak)) read_persistent_clock(struct timespec *ts) |
8524070b | 490 | { |
d4f587c6 MS |
491 | ts->tv_sec = 0; |
492 | ts->tv_nsec = 0; | |
8524070b | 493 | } |
494 | ||
23970e38 MS |
495 | /** |
496 | * read_boot_clock - Return time of the system start. | |
497 | * | |
498 | * Weak dummy function for arches that do not yet support it. | |
499 | * Function to read the exact time the system has been started. | |
500 | * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported. | |
501 | * | |
502 | * XXX - Do be sure to remove it once all arches implement it. | |
503 | */ | |
504 | void __attribute__((weak)) read_boot_clock(struct timespec *ts) | |
505 | { | |
506 | ts->tv_sec = 0; | |
507 | ts->tv_nsec = 0; | |
508 | } | |
509 | ||
8524070b | 510 | /* |
511 | * timekeeping_init - Initializes the clocksource and common timekeeping values | |
512 | */ | |
513 | void __init timekeeping_init(void) | |
514 | { | |
155ec602 | 515 | struct clocksource *clock; |
8524070b | 516 | unsigned long flags; |
23970e38 | 517 | struct timespec now, boot; |
d4f587c6 MS |
518 | |
519 | read_persistent_clock(&now); | |
23970e38 | 520 | read_boot_clock(&boot); |
8524070b | 521 | |
522 | write_seqlock_irqsave(&xtime_lock, flags); | |
523 | ||
7dffa3c6 | 524 | ntp_init(); |
8524070b | 525 | |
f1b82746 | 526 | clock = clocksource_default_clock(); |
a0f7d48b MS |
527 | if (clock->enable) |
528 | clock->enable(clock); | |
155ec602 | 529 | timekeeper_setup_internals(clock); |
8524070b | 530 | |
d4f587c6 MS |
531 | xtime.tv_sec = now.tv_sec; |
532 | xtime.tv_nsec = now.tv_nsec; | |
155ec602 MS |
533 | raw_time.tv_sec = 0; |
534 | raw_time.tv_nsec = 0; | |
23970e38 MS |
535 | if (boot.tv_sec == 0 && boot.tv_nsec == 0) { |
536 | boot.tv_sec = xtime.tv_sec; | |
537 | boot.tv_nsec = xtime.tv_nsec; | |
538 | } | |
8524070b | 539 | set_normalized_timespec(&wall_to_monotonic, |
23970e38 | 540 | -boot.tv_sec, -boot.tv_nsec); |
d4f587c6 MS |
541 | total_sleep_time.tv_sec = 0; |
542 | total_sleep_time.tv_nsec = 0; | |
8524070b | 543 | write_sequnlock_irqrestore(&xtime_lock, flags); |
544 | } | |
545 | ||
8524070b | 546 | /* time in seconds when suspend began */ |
d4f587c6 | 547 | static struct timespec timekeeping_suspend_time; |
8524070b | 548 | |
549 | /** | |
550 | * timekeeping_resume - Resumes the generic timekeeping subsystem. | |
551 | * @dev: unused | |
552 | * | |
553 | * This is for the generic clocksource timekeeping. | |
554 | * xtime/wall_to_monotonic/jiffies/etc are | |
555 | * still managed by arch specific suspend/resume code. | |
556 | */ | |
557 | static int timekeeping_resume(struct sys_device *dev) | |
558 | { | |
559 | unsigned long flags; | |
d4f587c6 MS |
560 | struct timespec ts; |
561 | ||
562 | read_persistent_clock(&ts); | |
8524070b | 563 | |
d10ff3fb TG |
564 | clocksource_resume(); |
565 | ||
8524070b | 566 | write_seqlock_irqsave(&xtime_lock, flags); |
567 | ||
d4f587c6 MS |
568 | if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) { |
569 | ts = timespec_sub(ts, timekeeping_suspend_time); | |
570 | xtime = timespec_add_safe(xtime, ts); | |
571 | wall_to_monotonic = timespec_sub(wall_to_monotonic, ts); | |
572 | total_sleep_time = timespec_add_safe(total_sleep_time, ts); | |
8524070b | 573 | } |
574 | /* re-base the last cycle value */ | |
155ec602 MS |
575 | timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock); |
576 | timekeeper.ntp_error = 0; | |
8524070b | 577 | timekeeping_suspended = 0; |
578 | write_sequnlock_irqrestore(&xtime_lock, flags); | |
579 | ||
580 | touch_softlockup_watchdog(); | |
581 | ||
582 | clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); | |
583 | ||
584 | /* Resume hrtimers */ | |
585 | hres_timers_resume(); | |
586 | ||
587 | return 0; | |
588 | } | |
589 | ||
590 | static int timekeeping_suspend(struct sys_device *dev, pm_message_t state) | |
591 | { | |
592 | unsigned long flags; | |
593 | ||
d4f587c6 | 594 | read_persistent_clock(&timekeeping_suspend_time); |
3be90950 | 595 | |
8524070b | 596 | write_seqlock_irqsave(&xtime_lock, flags); |
155ec602 | 597 | timekeeping_forward_now(); |
8524070b | 598 | timekeeping_suspended = 1; |
8524070b | 599 | write_sequnlock_irqrestore(&xtime_lock, flags); |
600 | ||
601 | clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); | |
602 | ||
603 | return 0; | |
604 | } | |
605 | ||
606 | /* sysfs resume/suspend bits for timekeeping */ | |
607 | static struct sysdev_class timekeeping_sysclass = { | |
af5ca3f4 | 608 | .name = "timekeeping", |
8524070b | 609 | .resume = timekeeping_resume, |
610 | .suspend = timekeeping_suspend, | |
8524070b | 611 | }; |
612 | ||
613 | static struct sys_device device_timer = { | |
614 | .id = 0, | |
615 | .cls = &timekeeping_sysclass, | |
616 | }; | |
617 | ||
618 | static int __init timekeeping_init_device(void) | |
619 | { | |
620 | int error = sysdev_class_register(&timekeeping_sysclass); | |
621 | if (!error) | |
622 | error = sysdev_register(&device_timer); | |
623 | return error; | |
624 | } | |
625 | ||
626 | device_initcall(timekeeping_init_device); | |
627 | ||
628 | /* | |
629 | * If the error is already larger, we look ahead even further | |
630 | * to compensate for late or lost adjustments. | |
631 | */ | |
155ec602 | 632 | static __always_inline int timekeeping_bigadjust(s64 error, s64 *interval, |
8524070b | 633 | s64 *offset) |
634 | { | |
635 | s64 tick_error, i; | |
636 | u32 look_ahead, adj; | |
637 | s32 error2, mult; | |
638 | ||
639 | /* | |
640 | * Use the current error value to determine how much to look ahead. | |
641 | * The larger the error the slower we adjust for it to avoid problems | |
642 | * with losing too many ticks, otherwise we would overadjust and | |
643 | * produce an even larger error. The smaller the adjustment the | |
644 | * faster we try to adjust for it, as lost ticks can do less harm | |
3eb05676 | 645 | * here. This is tuned so that an error of about 1 msec is adjusted |
8524070b | 646 | * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks). |
647 | */ | |
155ec602 | 648 | error2 = timekeeper.ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ); |
8524070b | 649 | error2 = abs(error2); |
650 | for (look_ahead = 0; error2 > 0; look_ahead++) | |
651 | error2 >>= 2; | |
652 | ||
653 | /* | |
654 | * Now calculate the error in (1 << look_ahead) ticks, but first | |
655 | * remove the single look ahead already included in the error. | |
656 | */ | |
23ce7211 | 657 | tick_error = tick_length >> (timekeeper.ntp_error_shift + 1); |
155ec602 | 658 | tick_error -= timekeeper.xtime_interval >> 1; |
8524070b | 659 | error = ((error - tick_error) >> look_ahead) + tick_error; |
660 | ||
661 | /* Finally calculate the adjustment shift value. */ | |
662 | i = *interval; | |
663 | mult = 1; | |
664 | if (error < 0) { | |
665 | error = -error; | |
666 | *interval = -*interval; | |
667 | *offset = -*offset; | |
668 | mult = -1; | |
669 | } | |
670 | for (adj = 0; error > i; adj++) | |
671 | error >>= 1; | |
672 | ||
673 | *interval <<= adj; | |
674 | *offset <<= adj; | |
675 | return mult << adj; | |
676 | } | |
677 | ||
678 | /* | |
679 | * Adjust the multiplier to reduce the error value, | |
680 | * this is optimized for the most common adjustments of -1,0,1, | |
681 | * for other values we can do a bit more work. | |
682 | */ | |
155ec602 | 683 | static void timekeeping_adjust(s64 offset) |
8524070b | 684 | { |
155ec602 | 685 | s64 error, interval = timekeeper.cycle_interval; |
8524070b | 686 | int adj; |
687 | ||
23ce7211 | 688 | error = timekeeper.ntp_error >> (timekeeper.ntp_error_shift - 1); |
8524070b | 689 | if (error > interval) { |
690 | error >>= 2; | |
691 | if (likely(error <= interval)) | |
692 | adj = 1; | |
693 | else | |
155ec602 | 694 | adj = timekeeping_bigadjust(error, &interval, &offset); |
8524070b | 695 | } else if (error < -interval) { |
696 | error >>= 2; | |
697 | if (likely(error >= -interval)) { | |
698 | adj = -1; | |
699 | interval = -interval; | |
700 | offset = -offset; | |
701 | } else | |
155ec602 | 702 | adj = timekeeping_bigadjust(error, &interval, &offset); |
8524070b | 703 | } else |
704 | return; | |
705 | ||
0a544198 | 706 | timekeeper.mult += adj; |
155ec602 MS |
707 | timekeeper.xtime_interval += interval; |
708 | timekeeper.xtime_nsec -= offset; | |
709 | timekeeper.ntp_error -= (interval - offset) << | |
23ce7211 | 710 | timekeeper.ntp_error_shift; |
8524070b | 711 | } |
712 | ||
a092ff0f | 713 | /** |
714 | * logarithmic_accumulation - shifted accumulation of cycles | |
715 | * | |
716 | * This functions accumulates a shifted interval of cycles into | |
717 | * into a shifted interval nanoseconds. Allows for O(log) accumulation | |
718 | * loop. | |
719 | * | |
720 | * Returns the unconsumed cycles. | |
721 | */ | |
722 | static cycle_t logarithmic_accumulation(cycle_t offset, int shift) | |
723 | { | |
724 | u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift; | |
725 | ||
726 | /* If the offset is smaller then a shifted interval, do nothing */ | |
727 | if (offset < timekeeper.cycle_interval<<shift) | |
728 | return offset; | |
729 | ||
730 | /* Accumulate one shifted interval */ | |
731 | offset -= timekeeper.cycle_interval << shift; | |
732 | timekeeper.clock->cycle_last += timekeeper.cycle_interval << shift; | |
733 | ||
734 | timekeeper.xtime_nsec += timekeeper.xtime_interval << shift; | |
735 | while (timekeeper.xtime_nsec >= nsecps) { | |
736 | timekeeper.xtime_nsec -= nsecps; | |
737 | xtime.tv_sec++; | |
738 | second_overflow(); | |
739 | } | |
740 | ||
741 | /* Accumulate into raw time */ | |
742 | raw_time.tv_nsec += timekeeper.raw_interval << shift;; | |
743 | while (raw_time.tv_nsec >= NSEC_PER_SEC) { | |
744 | raw_time.tv_nsec -= NSEC_PER_SEC; | |
745 | raw_time.tv_sec++; | |
746 | } | |
747 | ||
748 | /* Accumulate error between NTP and clock interval */ | |
749 | timekeeper.ntp_error += tick_length << shift; | |
750 | timekeeper.ntp_error -= timekeeper.xtime_interval << | |
751 | (timekeeper.ntp_error_shift + shift); | |
752 | ||
753 | return offset; | |
754 | } | |
755 | ||
8524070b | 756 | /** |
757 | * update_wall_time - Uses the current clocksource to increment the wall time | |
758 | * | |
759 | * Called from the timer interrupt, must hold a write on xtime_lock. | |
760 | */ | |
761 | void update_wall_time(void) | |
762 | { | |
155ec602 | 763 | struct clocksource *clock; |
8524070b | 764 | cycle_t offset; |
a092ff0f | 765 | int shift = 0, maxshift; |
8524070b | 766 | |
767 | /* Make sure we're fully resumed: */ | |
768 | if (unlikely(timekeeping_suspended)) | |
769 | return; | |
770 | ||
155ec602 | 771 | clock = timekeeper.clock; |
8524070b | 772 | #ifdef CONFIG_GENERIC_TIME |
a0f7d48b | 773 | offset = (clock->read(clock) - clock->cycle_last) & clock->mask; |
8524070b | 774 | #else |
155ec602 | 775 | offset = timekeeper.cycle_interval; |
8524070b | 776 | #endif |
23ce7211 | 777 | timekeeper.xtime_nsec = (s64)xtime.tv_nsec << timekeeper.shift; |
8524070b | 778 | |
a092ff0f | 779 | /* |
780 | * With NO_HZ we may have to accumulate many cycle_intervals | |
781 | * (think "ticks") worth of time at once. To do this efficiently, | |
782 | * we calculate the largest doubling multiple of cycle_intervals | |
783 | * that is smaller then the offset. We then accumulate that | |
784 | * chunk in one go, and then try to consume the next smaller | |
785 | * doubled multiple. | |
8524070b | 786 | */ |
a092ff0f | 787 | shift = ilog2(offset) - ilog2(timekeeper.cycle_interval); |
788 | shift = max(0, shift); | |
789 | /* Bound shift to one less then what overflows tick_length */ | |
790 | maxshift = (8*sizeof(tick_length) - (ilog2(tick_length)+1)) - 1; | |
791 | shift = min(shift, maxshift); | |
155ec602 | 792 | while (offset >= timekeeper.cycle_interval) { |
a092ff0f | 793 | offset = logarithmic_accumulation(offset, shift); |
794 | shift--; | |
8524070b | 795 | } |
796 | ||
797 | /* correct the clock when NTP error is too big */ | |
155ec602 | 798 | timekeeping_adjust(offset); |
8524070b | 799 | |
6c9bacb4 | 800 | /* |
801 | * Since in the loop above, we accumulate any amount of time | |
802 | * in xtime_nsec over a second into xtime.tv_sec, its possible for | |
803 | * xtime_nsec to be fairly small after the loop. Further, if we're | |
155ec602 | 804 | * slightly speeding the clocksource up in timekeeping_adjust(), |
6c9bacb4 | 805 | * its possible the required corrective factor to xtime_nsec could |
806 | * cause it to underflow. | |
807 | * | |
808 | * Now, we cannot simply roll the accumulated second back, since | |
809 | * the NTP subsystem has been notified via second_overflow. So | |
810 | * instead we push xtime_nsec forward by the amount we underflowed, | |
811 | * and add that amount into the error. | |
812 | * | |
813 | * We'll correct this error next time through this function, when | |
814 | * xtime_nsec is not as small. | |
815 | */ | |
155ec602 MS |
816 | if (unlikely((s64)timekeeper.xtime_nsec < 0)) { |
817 | s64 neg = -(s64)timekeeper.xtime_nsec; | |
818 | timekeeper.xtime_nsec = 0; | |
23ce7211 | 819 | timekeeper.ntp_error += neg << timekeeper.ntp_error_shift; |
6c9bacb4 | 820 | } |
821 | ||
5cd1c9c5 RZ |
822 | /* store full nanoseconds into xtime after rounding it up and |
823 | * add the remainder to the error difference. | |
824 | */ | |
23ce7211 MS |
825 | xtime.tv_nsec = ((s64) timekeeper.xtime_nsec >> timekeeper.shift) + 1; |
826 | timekeeper.xtime_nsec -= (s64) xtime.tv_nsec << timekeeper.shift; | |
827 | timekeeper.ntp_error += timekeeper.xtime_nsec << | |
828 | timekeeper.ntp_error_shift; | |
8524070b | 829 | |
830 | /* check to see if there is a new clocksource to use */ | |
155ec602 | 831 | update_vsyscall(&xtime, timekeeper.clock); |
8524070b | 832 | } |
7c3f1a57 TJ |
833 | |
834 | /** | |
835 | * getboottime - Return the real time of system boot. | |
836 | * @ts: pointer to the timespec to be set | |
837 | * | |
838 | * Returns the time of day in a timespec. | |
839 | * | |
840 | * This is based on the wall_to_monotonic offset and the total suspend | |
841 | * time. Calls to settimeofday will affect the value returned (which | |
842 | * basically means that however wrong your real time clock is at boot time, | |
843 | * you get the right time here). | |
844 | */ | |
845 | void getboottime(struct timespec *ts) | |
846 | { | |
36d47481 HS |
847 | struct timespec boottime = { |
848 | .tv_sec = wall_to_monotonic.tv_sec + total_sleep_time.tv_sec, | |
849 | .tv_nsec = wall_to_monotonic.tv_nsec + total_sleep_time.tv_nsec | |
850 | }; | |
d4f587c6 | 851 | |
d4f587c6 | 852 | set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec); |
7c3f1a57 TJ |
853 | } |
854 | ||
855 | /** | |
856 | * monotonic_to_bootbased - Convert the monotonic time to boot based. | |
857 | * @ts: pointer to the timespec to be converted | |
858 | */ | |
859 | void monotonic_to_bootbased(struct timespec *ts) | |
860 | { | |
d4f587c6 | 861 | *ts = timespec_add_safe(*ts, total_sleep_time); |
7c3f1a57 | 862 | } |
2c6b47de | 863 | |
17c38b74 | 864 | unsigned long get_seconds(void) |
865 | { | |
7bc7d637 | 866 | return xtime.tv_sec; |
17c38b74 | 867 | } |
868 | EXPORT_SYMBOL(get_seconds); | |
869 | ||
da15cfda | 870 | struct timespec __current_kernel_time(void) |
871 | { | |
7bc7d637 | 872 | return xtime; |
da15cfda | 873 | } |
17c38b74 | 874 | |
2c6b47de | 875 | struct timespec current_kernel_time(void) |
876 | { | |
877 | struct timespec now; | |
878 | unsigned long seq; | |
879 | ||
880 | do { | |
881 | seq = read_seqbegin(&xtime_lock); | |
7bc7d637 | 882 | now = xtime; |
2c6b47de | 883 | } while (read_seqretry(&xtime_lock, seq)); |
884 | ||
885 | return now; | |
886 | } | |
2c6b47de | 887 | EXPORT_SYMBOL(current_kernel_time); |
da15cfda | 888 | |
889 | struct timespec get_monotonic_coarse(void) | |
890 | { | |
891 | struct timespec now, mono; | |
892 | unsigned long seq; | |
893 | ||
894 | do { | |
895 | seq = read_seqbegin(&xtime_lock); | |
7bc7d637 | 896 | now = xtime; |
da15cfda | 897 | mono = wall_to_monotonic; |
898 | } while (read_seqretry(&xtime_lock, seq)); | |
899 | ||
900 | set_normalized_timespec(&now, now.tv_sec + mono.tv_sec, | |
901 | now.tv_nsec + mono.tv_nsec); | |
902 | return now; | |
903 | } |