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1 | /* | |
2 | * linux/kernel/time/clocksource.c | |
3 | * | |
4 | * This file contains the functions which manage clocksource drivers. | |
5 | * | |
6 | * Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2 of the License, or | |
11 | * (at your option) any later version. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program; if not, write to the Free Software | |
20 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
21 | * | |
22 | * TODO WishList: | |
23 | * o Allow clocksource drivers to be unregistered | |
24 | */ | |
25 | ||
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> /* for spin_unlock_irq() using preempt_count() m68k */ | |
31 | #include <linux/tick.h> | |
32 | ||
33 | void timecounter_init(struct timecounter *tc, | |
34 | const struct cyclecounter *cc, | |
35 | u64 start_tstamp) | |
36 | { | |
37 | tc->cc = cc; | |
38 | tc->cycle_last = cc->read(cc); | |
39 | tc->nsec = start_tstamp; | |
40 | } | |
41 | EXPORT_SYMBOL(timecounter_init); | |
42 | ||
43 | /** | |
44 | * timecounter_read_delta - get nanoseconds since last call of this function | |
45 | * @tc: Pointer to time counter | |
46 | * | |
47 | * When the underlying cycle counter runs over, this will be handled | |
48 | * correctly as long as it does not run over more than once between | |
49 | * calls. | |
50 | * | |
51 | * The first call to this function for a new time counter initializes | |
52 | * the time tracking and returns an undefined result. | |
53 | */ | |
54 | static u64 timecounter_read_delta(struct timecounter *tc) | |
55 | { | |
56 | cycle_t cycle_now, cycle_delta; | |
57 | u64 ns_offset; | |
58 | ||
59 | /* read cycle counter: */ | |
60 | cycle_now = tc->cc->read(tc->cc); | |
61 | ||
62 | /* calculate the delta since the last timecounter_read_delta(): */ | |
63 | cycle_delta = (cycle_now - tc->cycle_last) & tc->cc->mask; | |
64 | ||
65 | /* convert to nanoseconds: */ | |
66 | ns_offset = cyclecounter_cyc2ns(tc->cc, cycle_delta); | |
67 | ||
68 | /* update time stamp of timecounter_read_delta() call: */ | |
69 | tc->cycle_last = cycle_now; | |
70 | ||
71 | return ns_offset; | |
72 | } | |
73 | ||
74 | u64 timecounter_read(struct timecounter *tc) | |
75 | { | |
76 | u64 nsec; | |
77 | ||
78 | /* increment time by nanoseconds since last call */ | |
79 | nsec = timecounter_read_delta(tc); | |
80 | nsec += tc->nsec; | |
81 | tc->nsec = nsec; | |
82 | ||
83 | return nsec; | |
84 | } | |
85 | EXPORT_SYMBOL(timecounter_read); | |
86 | ||
87 | u64 timecounter_cyc2time(struct timecounter *tc, | |
88 | cycle_t cycle_tstamp) | |
89 | { | |
90 | u64 cycle_delta = (cycle_tstamp - tc->cycle_last) & tc->cc->mask; | |
91 | u64 nsec; | |
92 | ||
93 | /* | |
94 | * Instead of always treating cycle_tstamp as more recent | |
95 | * than tc->cycle_last, detect when it is too far in the | |
96 | * future and treat it as old time stamp instead. | |
97 | */ | |
98 | if (cycle_delta > tc->cc->mask / 2) { | |
99 | cycle_delta = (tc->cycle_last - cycle_tstamp) & tc->cc->mask; | |
100 | nsec = tc->nsec - cyclecounter_cyc2ns(tc->cc, cycle_delta); | |
101 | } else { | |
102 | nsec = cyclecounter_cyc2ns(tc->cc, cycle_delta) + tc->nsec; | |
103 | } | |
104 | ||
105 | return nsec; | |
106 | } | |
107 | EXPORT_SYMBOL(timecounter_cyc2time); | |
108 | ||
109 | /*[Clocksource internal variables]--------- | |
110 | * curr_clocksource: | |
111 | * currently selected clocksource. | |
112 | * next_clocksource: | |
113 | * pending next selected clocksource. | |
114 | * clocksource_list: | |
115 | * linked list with the registered clocksources | |
116 | * clocksource_lock: | |
117 | * protects manipulations to curr_clocksource and next_clocksource | |
118 | * and the clocksource_list | |
119 | * override_name: | |
120 | * Name of the user-specified clocksource. | |
121 | */ | |
122 | static struct clocksource *curr_clocksource; | |
123 | static struct clocksource *next_clocksource; | |
124 | static LIST_HEAD(clocksource_list); | |
125 | static DEFINE_SPINLOCK(clocksource_lock); | |
126 | static char override_name[32]; | |
127 | static int finished_booting; | |
128 | ||
129 | /* clocksource_done_booting - Called near the end of core bootup | |
130 | * | |
131 | * Hack to avoid lots of clocksource churn at boot time. | |
132 | * We use fs_initcall because we want this to start before | |
133 | * device_initcall but after subsys_initcall. | |
134 | */ | |
135 | static int __init clocksource_done_booting(void) | |
136 | { | |
137 | finished_booting = 1; | |
138 | return 0; | |
139 | } | |
140 | fs_initcall(clocksource_done_booting); | |
141 | ||
142 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG | |
143 | static LIST_HEAD(watchdog_list); | |
144 | static struct clocksource *watchdog; | |
145 | static struct timer_list watchdog_timer; | |
146 | static struct work_struct watchdog_work; | |
147 | static DEFINE_SPINLOCK(watchdog_lock); | |
148 | static cycle_t watchdog_last; | |
149 | static int watchdog_running; | |
150 | ||
151 | static void clocksource_watchdog_work(struct work_struct *work); | |
152 | ||
153 | /* | |
154 | * Interval: 0.5sec Threshold: 0.0625s | |
155 | */ | |
156 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
157 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) | |
158 | ||
159 | static void clocksource_unstable(struct clocksource *cs, int64_t delta) | |
160 | { | |
161 | printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n", | |
162 | cs->name, delta); | |
163 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); | |
164 | cs->flags |= CLOCK_SOURCE_UNSTABLE; | |
165 | schedule_work(&watchdog_work); | |
166 | } | |
167 | ||
168 | static void clocksource_watchdog(unsigned long data) | |
169 | { | |
170 | struct clocksource *cs; | |
171 | cycle_t csnow, wdnow; | |
172 | int64_t wd_nsec, cs_nsec; | |
173 | int next_cpu; | |
174 | ||
175 | spin_lock(&watchdog_lock); | |
176 | if (!watchdog_running) | |
177 | goto out; | |
178 | ||
179 | wdnow = watchdog->read(watchdog); | |
180 | wd_nsec = cyc2ns(watchdog, (wdnow - watchdog_last) & watchdog->mask); | |
181 | watchdog_last = wdnow; | |
182 | ||
183 | list_for_each_entry(cs, &watchdog_list, wd_list) { | |
184 | ||
185 | /* Clocksource already marked unstable? */ | |
186 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) | |
187 | continue; | |
188 | ||
189 | csnow = cs->read(cs); | |
190 | ||
191 | /* Clocksource initialized ? */ | |
192 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG)) { | |
193 | cs->flags |= CLOCK_SOURCE_WATCHDOG; | |
194 | cs->wd_last = csnow; | |
195 | continue; | |
196 | } | |
197 | ||
198 | /* Check the deviation from the watchdog clocksource. */ | |
199 | cs_nsec = cyc2ns(cs, (csnow - cs->wd_last) & cs->mask); | |
200 | cs->wd_last = csnow; | |
201 | if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) { | |
202 | clocksource_unstable(cs, cs_nsec - wd_nsec); | |
203 | continue; | |
204 | } | |
205 | ||
206 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && | |
207 | (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
208 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
209 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
210 | /* | |
211 | * We just marked the clocksource as highres-capable, | |
212 | * notify the rest of the system as well so that we | |
213 | * transition into high-res mode: | |
214 | */ | |
215 | tick_clock_notify(); | |
216 | } | |
217 | } | |
218 | ||
219 | /* | |
220 | * Cycle through CPUs to check if the CPUs stay synchronized | |
221 | * to each other. | |
222 | */ | |
223 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); | |
224 | if (next_cpu >= nr_cpu_ids) | |
225 | next_cpu = cpumask_first(cpu_online_mask); | |
226 | watchdog_timer.expires += WATCHDOG_INTERVAL; | |
227 | add_timer_on(&watchdog_timer, next_cpu); | |
228 | out: | |
229 | spin_unlock(&watchdog_lock); | |
230 | } | |
231 | ||
232 | static inline void clocksource_start_watchdog(void) | |
233 | { | |
234 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) | |
235 | return; | |
236 | INIT_WORK(&watchdog_work, clocksource_watchdog_work); | |
237 | init_timer(&watchdog_timer); | |
238 | watchdog_timer.function = clocksource_watchdog; | |
239 | watchdog_last = watchdog->read(watchdog); | |
240 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; | |
241 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); | |
242 | watchdog_running = 1; | |
243 | } | |
244 | ||
245 | static inline void clocksource_stop_watchdog(void) | |
246 | { | |
247 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) | |
248 | return; | |
249 | del_timer(&watchdog_timer); | |
250 | watchdog_running = 0; | |
251 | } | |
252 | ||
253 | static inline void clocksource_reset_watchdog(void) | |
254 | { | |
255 | struct clocksource *cs; | |
256 | ||
257 | list_for_each_entry(cs, &watchdog_list, wd_list) | |
258 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
259 | } | |
260 | ||
261 | static void clocksource_resume_watchdog(void) | |
262 | { | |
263 | unsigned long flags; | |
264 | ||
265 | spin_lock_irqsave(&watchdog_lock, flags); | |
266 | clocksource_reset_watchdog(); | |
267 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
268 | } | |
269 | ||
270 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
271 | { | |
272 | unsigned long flags; | |
273 | ||
274 | spin_lock_irqsave(&watchdog_lock, flags); | |
275 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
276 | /* cs is a clocksource to be watched. */ | |
277 | list_add(&cs->wd_list, &watchdog_list); | |
278 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
279 | } else { | |
280 | /* cs is a watchdog. */ | |
281 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
282 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
283 | /* Pick the best watchdog. */ | |
284 | if (!watchdog || cs->rating > watchdog->rating) { | |
285 | watchdog = cs; | |
286 | /* Reset watchdog cycles */ | |
287 | clocksource_reset_watchdog(); | |
288 | } | |
289 | } | |
290 | /* Check if the watchdog timer needs to be started. */ | |
291 | clocksource_start_watchdog(); | |
292 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
293 | } | |
294 | ||
295 | static void clocksource_dequeue_watchdog(struct clocksource *cs) | |
296 | { | |
297 | struct clocksource *tmp; | |
298 | unsigned long flags; | |
299 | ||
300 | spin_lock_irqsave(&watchdog_lock, flags); | |
301 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
302 | /* cs is a watched clocksource. */ | |
303 | list_del_init(&cs->wd_list); | |
304 | } else if (cs == watchdog) { | |
305 | /* Reset watchdog cycles */ | |
306 | clocksource_reset_watchdog(); | |
307 | /* Current watchdog is removed. Find an alternative. */ | |
308 | watchdog = NULL; | |
309 | list_for_each_entry(tmp, &clocksource_list, list) { | |
310 | if (tmp == cs || tmp->flags & CLOCK_SOURCE_MUST_VERIFY) | |
311 | continue; | |
312 | if (!watchdog || tmp->rating > watchdog->rating) | |
313 | watchdog = tmp; | |
314 | } | |
315 | } | |
316 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
317 | /* Check if the watchdog timer needs to be stopped. */ | |
318 | clocksource_stop_watchdog(); | |
319 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
320 | } | |
321 | ||
322 | static void clocksource_watchdog_work(struct work_struct *work) | |
323 | { | |
324 | struct clocksource *cs, *tmp; | |
325 | unsigned long flags; | |
326 | ||
327 | spin_lock_irqsave(&watchdog_lock, flags); | |
328 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) | |
329 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { | |
330 | list_del_init(&cs->wd_list); | |
331 | clocksource_change_rating(cs, 0); | |
332 | } | |
333 | /* Check if the watchdog timer needs to be stopped. */ | |
334 | clocksource_stop_watchdog(); | |
335 | spin_unlock(&watchdog_lock); | |
336 | } | |
337 | ||
338 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ | |
339 | ||
340 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
341 | { | |
342 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
343 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
344 | } | |
345 | ||
346 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } | |
347 | static inline void clocksource_resume_watchdog(void) { } | |
348 | ||
349 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ | |
350 | ||
351 | /** | |
352 | * clocksource_resume - resume the clocksource(s) | |
353 | */ | |
354 | void clocksource_resume(void) | |
355 | { | |
356 | struct clocksource *cs; | |
357 | unsigned long flags; | |
358 | ||
359 | spin_lock_irqsave(&clocksource_lock, flags); | |
360 | ||
361 | list_for_each_entry(cs, &clocksource_list, list) { | |
362 | if (cs->resume) | |
363 | cs->resume(); | |
364 | } | |
365 | ||
366 | clocksource_resume_watchdog(); | |
367 | ||
368 | spin_unlock_irqrestore(&clocksource_lock, flags); | |
369 | } | |
370 | ||
371 | /** | |
372 | * clocksource_touch_watchdog - Update watchdog | |
373 | * | |
374 | * Update the watchdog after exception contexts such as kgdb so as not | |
375 | * to incorrectly trip the watchdog. | |
376 | * | |
377 | */ | |
378 | void clocksource_touch_watchdog(void) | |
379 | { | |
380 | clocksource_resume_watchdog(); | |
381 | } | |
382 | ||
383 | #ifdef CONFIG_GENERIC_TIME | |
384 | /** | |
385 | * clocksource_get_next - Returns the selected clocksource | |
386 | * | |
387 | */ | |
388 | struct clocksource *clocksource_get_next(void) | |
389 | { | |
390 | unsigned long flags; | |
391 | ||
392 | spin_lock_irqsave(&clocksource_lock, flags); | |
393 | if (next_clocksource && finished_booting) { | |
394 | curr_clocksource = next_clocksource; | |
395 | next_clocksource = NULL; | |
396 | } | |
397 | spin_unlock_irqrestore(&clocksource_lock, flags); | |
398 | ||
399 | return curr_clocksource; | |
400 | } | |
401 | ||
402 | /** | |
403 | * clocksource_select - Select the best clocksource available | |
404 | * | |
405 | * Private function. Must hold clocksource_lock when called. | |
406 | * | |
407 | * Select the clocksource with the best rating, or the clocksource, | |
408 | * which is selected by userspace override. | |
409 | */ | |
410 | static void clocksource_select(void) | |
411 | { | |
412 | struct clocksource *best, *cs; | |
413 | ||
414 | if (list_empty(&clocksource_list)) | |
415 | return; | |
416 | /* First clocksource on the list has the best rating. */ | |
417 | best = list_first_entry(&clocksource_list, struct clocksource, list); | |
418 | /* Check for the override clocksource. */ | |
419 | list_for_each_entry(cs, &clocksource_list, list) { | |
420 | if (strcmp(cs->name, override_name) != 0) | |
421 | continue; | |
422 | /* | |
423 | * Check to make sure we don't switch to a non-highres | |
424 | * capable clocksource if the tick code is in oneshot | |
425 | * mode (highres or nohz) | |
426 | */ | |
427 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && | |
428 | tick_oneshot_mode_active()) { | |
429 | /* Override clocksource cannot be used. */ | |
430 | printk(KERN_WARNING "Override clocksource %s is not " | |
431 | "HRT compatible. Cannot switch while in " | |
432 | "HRT/NOHZ mode\n", cs->name); | |
433 | override_name[0] = 0; | |
434 | } else | |
435 | /* Override clocksource can be used. */ | |
436 | best = cs; | |
437 | break; | |
438 | } | |
439 | if (curr_clocksource != best) | |
440 | next_clocksource = best; | |
441 | } | |
442 | ||
443 | #else /* CONFIG_GENERIC_TIME */ | |
444 | ||
445 | static void clocksource_select(void) { } | |
446 | ||
447 | #endif | |
448 | ||
449 | /* | |
450 | * Enqueue the clocksource sorted by rating | |
451 | */ | |
452 | static void clocksource_enqueue(struct clocksource *cs) | |
453 | { | |
454 | struct list_head *entry = &clocksource_list; | |
455 | struct clocksource *tmp; | |
456 | ||
457 | list_for_each_entry(tmp, &clocksource_list, list) | |
458 | /* Keep track of the place, where to insert */ | |
459 | if (tmp->rating >= cs->rating) | |
460 | entry = &tmp->list; | |
461 | list_add(&cs->list, entry); | |
462 | } | |
463 | ||
464 | /** | |
465 | * clocksource_register - Used to install new clocksources | |
466 | * @t: clocksource to be registered | |
467 | * | |
468 | * Returns -EBUSY if registration fails, zero otherwise. | |
469 | */ | |
470 | int clocksource_register(struct clocksource *cs) | |
471 | { | |
472 | unsigned long flags; | |
473 | ||
474 | spin_lock_irqsave(&clocksource_lock, flags); | |
475 | clocksource_enqueue(cs); | |
476 | clocksource_select(); | |
477 | spin_unlock_irqrestore(&clocksource_lock, flags); | |
478 | clocksource_enqueue_watchdog(cs); | |
479 | return 0; | |
480 | } | |
481 | EXPORT_SYMBOL(clocksource_register); | |
482 | ||
483 | /** | |
484 | * clocksource_change_rating - Change the rating of a registered clocksource | |
485 | */ | |
486 | void clocksource_change_rating(struct clocksource *cs, int rating) | |
487 | { | |
488 | unsigned long flags; | |
489 | ||
490 | spin_lock_irqsave(&clocksource_lock, flags); | |
491 | list_del(&cs->list); | |
492 | cs->rating = rating; | |
493 | clocksource_enqueue(cs); | |
494 | clocksource_select(); | |
495 | spin_unlock_irqrestore(&clocksource_lock, flags); | |
496 | } | |
497 | EXPORT_SYMBOL(clocksource_change_rating); | |
498 | ||
499 | /** | |
500 | * clocksource_unregister - remove a registered clocksource | |
501 | */ | |
502 | void clocksource_unregister(struct clocksource *cs) | |
503 | { | |
504 | unsigned long flags; | |
505 | ||
506 | clocksource_dequeue_watchdog(cs); | |
507 | spin_lock_irqsave(&clocksource_lock, flags); | |
508 | list_del(&cs->list); | |
509 | clocksource_select(); | |
510 | spin_unlock_irqrestore(&clocksource_lock, flags); | |
511 | } | |
512 | EXPORT_SYMBOL(clocksource_unregister); | |
513 | ||
514 | #ifdef CONFIG_SYSFS | |
515 | /** | |
516 | * sysfs_show_current_clocksources - sysfs interface for current clocksource | |
517 | * @dev: unused | |
518 | * @buf: char buffer to be filled with clocksource list | |
519 | * | |
520 | * Provides sysfs interface for listing current clocksource. | |
521 | */ | |
522 | static ssize_t | |
523 | sysfs_show_current_clocksources(struct sys_device *dev, | |
524 | struct sysdev_attribute *attr, char *buf) | |
525 | { | |
526 | ssize_t count = 0; | |
527 | ||
528 | spin_lock_irq(&clocksource_lock); | |
529 | count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); | |
530 | spin_unlock_irq(&clocksource_lock); | |
531 | ||
532 | return count; | |
533 | } | |
534 | ||
535 | /** | |
536 | * sysfs_override_clocksource - interface for manually overriding clocksource | |
537 | * @dev: unused | |
538 | * @buf: name of override clocksource | |
539 | * @count: length of buffer | |
540 | * | |
541 | * Takes input from sysfs interface for manually overriding the default | |
542 | * clocksource selction. | |
543 | */ | |
544 | static ssize_t sysfs_override_clocksource(struct sys_device *dev, | |
545 | struct sysdev_attribute *attr, | |
546 | const char *buf, size_t count) | |
547 | { | |
548 | size_t ret = count; | |
549 | ||
550 | /* strings from sysfs write are not 0 terminated! */ | |
551 | if (count >= sizeof(override_name)) | |
552 | return -EINVAL; | |
553 | ||
554 | /* strip of \n: */ | |
555 | if (buf[count-1] == '\n') | |
556 | count--; | |
557 | ||
558 | spin_lock_irq(&clocksource_lock); | |
559 | ||
560 | if (count > 0) | |
561 | memcpy(override_name, buf, count); | |
562 | override_name[count] = 0; | |
563 | clocksource_select(); | |
564 | ||
565 | spin_unlock_irq(&clocksource_lock); | |
566 | ||
567 | return ret; | |
568 | } | |
569 | ||
570 | /** | |
571 | * sysfs_show_available_clocksources - sysfs interface for listing clocksource | |
572 | * @dev: unused | |
573 | * @buf: char buffer to be filled with clocksource list | |
574 | * | |
575 | * Provides sysfs interface for listing registered clocksources | |
576 | */ | |
577 | static ssize_t | |
578 | sysfs_show_available_clocksources(struct sys_device *dev, | |
579 | struct sysdev_attribute *attr, | |
580 | char *buf) | |
581 | { | |
582 | struct clocksource *src; | |
583 | ssize_t count = 0; | |
584 | ||
585 | spin_lock_irq(&clocksource_lock); | |
586 | list_for_each_entry(src, &clocksource_list, list) { | |
587 | /* | |
588 | * Don't show non-HRES clocksource if the tick code is | |
589 | * in one shot mode (highres=on or nohz=on) | |
590 | */ | |
591 | if (!tick_oneshot_mode_active() || | |
592 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) | |
593 | count += snprintf(buf + count, | |
594 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), | |
595 | "%s ", src->name); | |
596 | } | |
597 | spin_unlock_irq(&clocksource_lock); | |
598 | ||
599 | count += snprintf(buf + count, | |
600 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); | |
601 | ||
602 | return count; | |
603 | } | |
604 | ||
605 | /* | |
606 | * Sysfs setup bits: | |
607 | */ | |
608 | static SYSDEV_ATTR(current_clocksource, 0644, sysfs_show_current_clocksources, | |
609 | sysfs_override_clocksource); | |
610 | ||
611 | static SYSDEV_ATTR(available_clocksource, 0444, | |
612 | sysfs_show_available_clocksources, NULL); | |
613 | ||
614 | static struct sysdev_class clocksource_sysclass = { | |
615 | .name = "clocksource", | |
616 | }; | |
617 | ||
618 | static struct sys_device device_clocksource = { | |
619 | .id = 0, | |
620 | .cls = &clocksource_sysclass, | |
621 | }; | |
622 | ||
623 | static int __init init_clocksource_sysfs(void) | |
624 | { | |
625 | int error = sysdev_class_register(&clocksource_sysclass); | |
626 | ||
627 | if (!error) | |
628 | error = sysdev_register(&device_clocksource); | |
629 | if (!error) | |
630 | error = sysdev_create_file( | |
631 | &device_clocksource, | |
632 | &attr_current_clocksource); | |
633 | if (!error) | |
634 | error = sysdev_create_file( | |
635 | &device_clocksource, | |
636 | &attr_available_clocksource); | |
637 | return error; | |
638 | } | |
639 | ||
640 | device_initcall(init_clocksource_sysfs); | |
641 | #endif /* CONFIG_SYSFS */ | |
642 | ||
643 | /** | |
644 | * boot_override_clocksource - boot clock override | |
645 | * @str: override name | |
646 | * | |
647 | * Takes a clocksource= boot argument and uses it | |
648 | * as the clocksource override name. | |
649 | */ | |
650 | static int __init boot_override_clocksource(char* str) | |
651 | { | |
652 | unsigned long flags; | |
653 | spin_lock_irqsave(&clocksource_lock, flags); | |
654 | if (str) | |
655 | strlcpy(override_name, str, sizeof(override_name)); | |
656 | spin_unlock_irqrestore(&clocksource_lock, flags); | |
657 | return 1; | |
658 | } | |
659 | ||
660 | __setup("clocksource=", boot_override_clocksource); | |
661 | ||
662 | /** | |
663 | * boot_override_clock - Compatibility layer for deprecated boot option | |
664 | * @str: override name | |
665 | * | |
666 | * DEPRECATED! Takes a clock= boot argument and uses it | |
667 | * as the clocksource override name | |
668 | */ | |
669 | static int __init boot_override_clock(char* str) | |
670 | { | |
671 | if (!strcmp(str, "pmtmr")) { | |
672 | printk("Warning: clock=pmtmr is deprecated. " | |
673 | "Use clocksource=acpi_pm.\n"); | |
674 | return boot_override_clocksource("acpi_pm"); | |
675 | } | |
676 | printk("Warning! clock= boot option is deprecated. " | |
677 | "Use clocksource=xyz\n"); | |
678 | return boot_override_clocksource(str); | |
679 | } | |
680 | ||
681 | __setup("clock=", boot_override_clock); |