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26#include <linux/clocksource.h>
27#include <linux/sysdev.h>
28#include <linux/init.h>
29#include <linux/module.h>
30#include <linux/sched.h>
31#include <linux/tick.h>
32#include <linux/kthread.h>
33
34void timecounter_init(struct timecounter *tc,
35 const struct cyclecounter *cc,
36 u64 start_tstamp)
37{
38 tc->cc = cc;
39 tc->cycle_last = cc->read(cc);
40 tc->nsec = start_tstamp;
41}
42EXPORT_SYMBOL(timecounter_init);
43
44
45
46
47
48
49
50
51
52
53
54
55static u64 timecounter_read_delta(struct timecounter *tc)
56{
57 cycle_t cycle_now, cycle_delta;
58 u64 ns_offset;
59
60
61 cycle_now = tc->cc->read(tc->cc);
62
63
64 cycle_delta = (cycle_now - tc->cycle_last) & tc->cc->mask;
65
66
67 ns_offset = cyclecounter_cyc2ns(tc->cc, cycle_delta);
68
69
70 tc->cycle_last = cycle_now;
71
72 return ns_offset;
73}
74
75u64 timecounter_read(struct timecounter *tc)
76{
77 u64 nsec;
78
79
80 nsec = timecounter_read_delta(tc);
81 nsec += tc->nsec;
82 tc->nsec = nsec;
83
84 return nsec;
85}
86EXPORT_SYMBOL(timecounter_read);
87
88u64 timecounter_cyc2time(struct timecounter *tc,
89 cycle_t cycle_tstamp)
90{
91 u64 cycle_delta = (cycle_tstamp - tc->cycle_last) & tc->cc->mask;
92 u64 nsec;
93
94
95
96
97
98
99 if (cycle_delta > tc->cc->mask / 2) {
100 cycle_delta = (tc->cycle_last - cycle_tstamp) & tc->cc->mask;
101 nsec = tc->nsec - cyclecounter_cyc2ns(tc->cc, cycle_delta);
102 } else {
103 nsec = cyclecounter_cyc2ns(tc->cc, cycle_delta) + tc->nsec;
104 }
105
106 return nsec;
107}
108EXPORT_SYMBOL(timecounter_cyc2time);
109
110
111
112
113
114
115
116
117
118
119
120static struct clocksource *curr_clocksource;
121static LIST_HEAD(clocksource_list);
122static DEFINE_MUTEX(clocksource_mutex);
123static char override_name[32];
124static int finished_booting;
125
126#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
127static void clocksource_watchdog_work(struct work_struct *work);
128
129static LIST_HEAD(watchdog_list);
130static struct clocksource *watchdog;
131static struct timer_list watchdog_timer;
132static DECLARE_WORK(watchdog_work, clocksource_watchdog_work);
133static DEFINE_SPINLOCK(watchdog_lock);
134static cycle_t watchdog_last;
135static int watchdog_running;
136
137static int clocksource_watchdog_kthread(void *data);
138static void __clocksource_change_rating(struct clocksource *cs, int rating);
139
140
141
142
143#define WATCHDOG_INTERVAL (HZ >> 1)
144#define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4)
145
146static void clocksource_watchdog_work(struct work_struct *work)
147{
148
149
150
151
152 kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog");
153}
154
155static void __clocksource_unstable(struct clocksource *cs)
156{
157 cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG);
158 cs->flags |= CLOCK_SOURCE_UNSTABLE;
159 if (finished_booting)
160 schedule_work(&watchdog_work);
161}
162
163static void clocksource_unstable(struct clocksource *cs, int64_t delta)
164{
165 printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n",
166 cs->name, delta);
167 __clocksource_unstable(cs);
168}
169
170
171
172
173
174
175
176
177
178
179void clocksource_mark_unstable(struct clocksource *cs)
180{
181 unsigned long flags;
182
183 spin_lock_irqsave(&watchdog_lock, flags);
184 if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) {
185 if (list_empty(&cs->wd_list))
186 list_add(&cs->wd_list, &watchdog_list);
187 __clocksource_unstable(cs);
188 }
189 spin_unlock_irqrestore(&watchdog_lock, flags);
190}
191
192static void clocksource_watchdog(unsigned long data)
193{
194 struct clocksource *cs;
195 cycle_t csnow, wdnow;
196 int64_t wd_nsec, cs_nsec;
197 int next_cpu;
198
199 spin_lock(&watchdog_lock);
200 if (!watchdog_running)
201 goto out;
202
203 wdnow = watchdog->read(watchdog);
204 wd_nsec = clocksource_cyc2ns((wdnow - watchdog_last) & watchdog->mask,
205 watchdog->mult, watchdog->shift);
206 watchdog_last = wdnow;
207
208 list_for_each_entry(cs, &watchdog_list, wd_list) {
209
210
211 if (cs->flags & CLOCK_SOURCE_UNSTABLE) {
212 if (finished_booting)
213 schedule_work(&watchdog_work);
214 continue;
215 }
216
217 csnow = cs->read(cs);
218
219
220 if (!(cs->flags & CLOCK_SOURCE_WATCHDOG)) {
221 cs->flags |= CLOCK_SOURCE_WATCHDOG;
222 cs->wd_last = csnow;
223 continue;
224 }
225
226
227 cs_nsec = clocksource_cyc2ns((csnow - cs->wd_last) &
228 cs->mask, cs->mult, cs->shift);
229 cs->wd_last = csnow;
230 if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) {
231 clocksource_unstable(cs, cs_nsec - wd_nsec);
232 continue;
233 }
234
235 if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) &&
236 (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) &&
237 (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) {
238 cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
239
240
241
242
243
244 tick_clock_notify();
245 }
246 }
247
248
249
250
251
252 next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask);
253 if (next_cpu >= nr_cpu_ids)
254 next_cpu = cpumask_first(cpu_online_mask);
255 watchdog_timer.expires += WATCHDOG_INTERVAL;
256 add_timer_on(&watchdog_timer, next_cpu);
257out:
258 spin_unlock(&watchdog_lock);
259}
260
261static inline void clocksource_start_watchdog(void)
262{
263 if (watchdog_running || !watchdog || list_empty(&watchdog_list))
264 return;
265 init_timer(&watchdog_timer);
266 watchdog_timer.function = clocksource_watchdog;
267 watchdog_last = watchdog->read(watchdog);
268 watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL;
269 add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask));
270 watchdog_running = 1;
271}
272
273static inline void clocksource_stop_watchdog(void)
274{
275 if (!watchdog_running || (watchdog && !list_empty(&watchdog_list)))
276 return;
277 del_timer(&watchdog_timer);
278 watchdog_running = 0;
279}
280
281static inline void clocksource_reset_watchdog(void)
282{
283 struct clocksource *cs;
284
285 list_for_each_entry(cs, &watchdog_list, wd_list)
286 cs->flags &= ~CLOCK_SOURCE_WATCHDOG;
287}
288
289static void clocksource_resume_watchdog(void)
290{
291 unsigned long flags;
292
293 spin_lock_irqsave(&watchdog_lock, flags);
294 clocksource_reset_watchdog();
295 spin_unlock_irqrestore(&watchdog_lock, flags);
296}
297
298static void clocksource_enqueue_watchdog(struct clocksource *cs)
299{
300 unsigned long flags;
301
302 spin_lock_irqsave(&watchdog_lock, flags);
303 if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) {
304
305 list_add(&cs->wd_list, &watchdog_list);
306 cs->flags &= ~CLOCK_SOURCE_WATCHDOG;
307 } else {
308
309 if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)
310 cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
311
312 if (!watchdog || cs->rating > watchdog->rating) {
313 watchdog = cs;
314
315 clocksource_reset_watchdog();
316 }
317 }
318
319 clocksource_start_watchdog();
320 spin_unlock_irqrestore(&watchdog_lock, flags);
321}
322
323static void clocksource_dequeue_watchdog(struct clocksource *cs)
324{
325 struct clocksource *tmp;
326 unsigned long flags;
327
328 spin_lock_irqsave(&watchdog_lock, flags);
329 if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) {
330
331 list_del_init(&cs->wd_list);
332 } else if (cs == watchdog) {
333
334 clocksource_reset_watchdog();
335
336 watchdog = NULL;
337 list_for_each_entry(tmp, &clocksource_list, list) {
338 if (tmp == cs || tmp->flags & CLOCK_SOURCE_MUST_VERIFY)
339 continue;
340 if (!watchdog || tmp->rating > watchdog->rating)
341 watchdog = tmp;
342 }
343 }
344 cs->flags &= ~CLOCK_SOURCE_WATCHDOG;
345
346 clocksource_stop_watchdog();
347 spin_unlock_irqrestore(&watchdog_lock, flags);
348}
349
350static int clocksource_watchdog_kthread(void *data)
351{
352 struct clocksource *cs, *tmp;
353 unsigned long flags;
354 LIST_HEAD(unstable);
355
356 mutex_lock(&clocksource_mutex);
357 spin_lock_irqsave(&watchdog_lock, flags);
358 list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list)
359 if (cs->flags & CLOCK_SOURCE_UNSTABLE) {
360 list_del_init(&cs->wd_list);
361 list_add(&cs->wd_list, &unstable);
362 }
363
364 clocksource_stop_watchdog();
365 spin_unlock_irqrestore(&watchdog_lock, flags);
366
367
368 list_for_each_entry_safe(cs, tmp, &unstable, wd_list) {
369 list_del_init(&cs->wd_list);
370 __clocksource_change_rating(cs, 0);
371 }
372 mutex_unlock(&clocksource_mutex);
373 return 0;
374}
375
376#else
377
378static void clocksource_enqueue_watchdog(struct clocksource *cs)
379{
380 if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)
381 cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
382}
383
384static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { }
385static inline void clocksource_resume_watchdog(void) { }
386static inline int clocksource_watchdog_kthread(void *data) { return 0; }
387
388#endif
389
390
391
392
393void clocksource_resume(void)
394{
395 struct clocksource *cs;
396
397 list_for_each_entry(cs, &clocksource_list, list)
398 if (cs->resume)
399 cs->resume();
400
401 clocksource_resume_watchdog();
402}
403
404
405
406
407
408
409
410
411void clocksource_touch_watchdog(void)
412{
413 clocksource_resume_watchdog();
414}
415
416#ifdef CONFIG_GENERIC_TIME
417
418
419
420
421
422
423
424
425
426static void clocksource_select(void)
427{
428 struct clocksource *best, *cs;
429
430 if (!finished_booting || list_empty(&clocksource_list))
431 return;
432
433 best = list_first_entry(&clocksource_list, struct clocksource, list);
434
435 list_for_each_entry(cs, &clocksource_list, list) {
436 if (strcmp(cs->name, override_name) != 0)
437 continue;
438
439
440
441
442
443 if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) &&
444 tick_oneshot_mode_active()) {
445
446 printk(KERN_WARNING "Override clocksource %s is not "
447 "HRT compatible. Cannot switch while in "
448 "HRT/NOHZ mode\n", cs->name);
449 override_name[0] = 0;
450 } else
451
452 best = cs;
453 break;
454 }
455 if (curr_clocksource != best) {
456 printk(KERN_INFO "Switching to clocksource %s\n", best->name);
457 curr_clocksource = best;
458 timekeeping_notify(curr_clocksource);
459 }
460}
461
462#else
463
464static inline void clocksource_select(void) { }
465
466#endif
467
468
469
470
471
472
473
474
475static int __init clocksource_done_booting(void)
476{
477 finished_booting = 1;
478
479
480
481
482 clocksource_watchdog_kthread(NULL);
483
484 mutex_lock(&clocksource_mutex);
485 clocksource_select();
486 mutex_unlock(&clocksource_mutex);
487 return 0;
488}
489fs_initcall(clocksource_done_booting);
490
491
492
493
494static void clocksource_enqueue(struct clocksource *cs)
495{
496 struct list_head *entry = &clocksource_list;
497 struct clocksource *tmp;
498
499 list_for_each_entry(tmp, &clocksource_list, list)
500
501 if (tmp->rating >= cs->rating)
502 entry = &tmp->list;
503 list_add(&cs->list, entry);
504}
505
506
507
508
509
510
511
512int clocksource_register(struct clocksource *cs)
513{
514 mutex_lock(&clocksource_mutex);
515 clocksource_enqueue(cs);
516 clocksource_select();
517 clocksource_enqueue_watchdog(cs);
518 mutex_unlock(&clocksource_mutex);
519 return 0;
520}
521EXPORT_SYMBOL(clocksource_register);
522
523static void __clocksource_change_rating(struct clocksource *cs, int rating)
524{
525 list_del(&cs->list);
526 cs->rating = rating;
527 clocksource_enqueue(cs);
528 clocksource_select();
529}
530
531
532
533
534void clocksource_change_rating(struct clocksource *cs, int rating)
535{
536 mutex_lock(&clocksource_mutex);
537 __clocksource_change_rating(cs, rating);
538 mutex_unlock(&clocksource_mutex);
539}
540EXPORT_SYMBOL(clocksource_change_rating);
541
542
543
544
545void clocksource_unregister(struct clocksource *cs)
546{
547 mutex_lock(&clocksource_mutex);
548 clocksource_dequeue_watchdog(cs);
549 list_del(&cs->list);
550 clocksource_select();
551 mutex_unlock(&clocksource_mutex);
552}
553EXPORT_SYMBOL(clocksource_unregister);
554
555#ifdef CONFIG_SYSFS
556
557
558
559
560
561
562
563static ssize_t
564sysfs_show_current_clocksources(struct sys_device *dev,
565 struct sysdev_attribute *attr, char *buf)
566{
567 ssize_t count = 0;
568
569 mutex_lock(&clocksource_mutex);
570 count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name);
571 mutex_unlock(&clocksource_mutex);
572
573 return count;
574}
575
576
577
578
579
580
581
582
583
584
585static ssize_t sysfs_override_clocksource(struct sys_device *dev,
586 struct sysdev_attribute *attr,
587 const char *buf, size_t count)
588{
589 size_t ret = count;
590
591
592 if (count >= sizeof(override_name))
593 return -EINVAL;
594
595
596 if (buf[count-1] == '\n')
597 count--;
598
599 mutex_lock(&clocksource_mutex);
600
601 if (count > 0)
602 memcpy(override_name, buf, count);
603 override_name[count] = 0;
604 clocksource_select();
605
606 mutex_unlock(&clocksource_mutex);
607
608 return ret;
609}
610
611
612
613
614
615
616
617
618static ssize_t
619sysfs_show_available_clocksources(struct sys_device *dev,
620 struct sysdev_attribute *attr,
621 char *buf)
622{
623 struct clocksource *src;
624 ssize_t count = 0;
625
626 mutex_lock(&clocksource_mutex);
627 list_for_each_entry(src, &clocksource_list, list) {
628
629
630
631
632 if (!tick_oneshot_mode_active() ||
633 (src->flags & CLOCK_SOURCE_VALID_FOR_HRES))
634 count += snprintf(buf + count,
635 max((ssize_t)PAGE_SIZE - count, (ssize_t)0),
636 "%s ", src->name);
637 }
638 mutex_unlock(&clocksource_mutex);
639
640 count += snprintf(buf + count,
641 max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n");
642
643 return count;
644}
645
646
647
648
649static SYSDEV_ATTR(current_clocksource, 0644, sysfs_show_current_clocksources,
650 sysfs_override_clocksource);
651
652static SYSDEV_ATTR(available_clocksource, 0444,
653 sysfs_show_available_clocksources, NULL);
654
655static struct sysdev_class clocksource_sysclass = {
656 .name = "clocksource",
657};
658
659static struct sys_device device_clocksource = {
660 .id = 0,
661 .cls = &clocksource_sysclass,
662};
663
664static int __init init_clocksource_sysfs(void)
665{
666 int error = sysdev_class_register(&clocksource_sysclass);
667
668 if (!error)
669 error = sysdev_register(&device_clocksource);
670 if (!error)
671 error = sysdev_create_file(
672 &device_clocksource,
673 &attr_current_clocksource);
674 if (!error)
675 error = sysdev_create_file(
676 &device_clocksource,
677 &attr_available_clocksource);
678 return error;
679}
680
681device_initcall(init_clocksource_sysfs);
682#endif
683
684
685
686
687
688
689
690
691static int __init boot_override_clocksource(char* str)
692{
693 mutex_lock(&clocksource_mutex);
694 if (str)
695 strlcpy(override_name, str, sizeof(override_name));
696 mutex_unlock(&clocksource_mutex);
697 return 1;
698}
699
700__setup("clocksource=", boot_override_clocksource);
701
702
703
704
705
706
707
708
709static int __init boot_override_clock(char* str)
710{
711 if (!strcmp(str, "pmtmr")) {
712 printk("Warning: clock=pmtmr is deprecated. "
713 "Use clocksource=acpi_pm.\n");
714 return boot_override_clocksource("acpi_pm");
715 }
716 printk("Warning! clock= boot option is deprecated. "
717 "Use clocksource=xyz\n");
718 return boot_override_clocksource(str);
719}
720
721__setup("clock=", boot_override_clock);
722