Commit | Line | Data |
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734efb46 | 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 | |
734efb46 | 24 | */ |
25 | ||
26 | #include <linux/clocksource.h> | |
27 | #include <linux/sysdev.h> | |
28 | #include <linux/init.h> | |
29 | #include <linux/module.h> | |
dc29a365 | 30 | #include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */ |
79bf2bb3 | 31 | #include <linux/tick.h> |
734efb46 | 32 | |
a038a353 PO |
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 | ||
734efb46 | 109 | /*[Clocksource internal variables]--------- |
110 | * curr_clocksource: | |
f1b82746 | 111 | * currently selected clocksource. |
734efb46 | 112 | * clocksource_list: |
113 | * linked list with the registered clocksources | |
75c5158f MS |
114 | * clocksource_mutex: |
115 | * protects manipulations to curr_clocksource and the clocksource_list | |
734efb46 | 116 | * override_name: |
117 | * Name of the user-specified clocksource. | |
118 | */ | |
f1b82746 | 119 | static struct clocksource *curr_clocksource; |
734efb46 | 120 | static LIST_HEAD(clocksource_list); |
75c5158f | 121 | static DEFINE_MUTEX(clocksource_mutex); |
734efb46 | 122 | static char override_name[32]; |
734efb46 | 123 | |
5d8b34fd TG |
124 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
125 | static LIST_HEAD(watchdog_list); | |
126 | static struct clocksource *watchdog; | |
127 | static struct timer_list watchdog_timer; | |
c55c87c8 | 128 | static struct work_struct watchdog_work; |
5d8b34fd TG |
129 | static DEFINE_SPINLOCK(watchdog_lock); |
130 | static cycle_t watchdog_last; | |
fb63a0eb | 131 | static int watchdog_running; |
b52f52a0 | 132 | |
c55c87c8 MS |
133 | static void clocksource_watchdog_work(struct work_struct *work); |
134 | ||
5d8b34fd | 135 | /* |
35c35d1a | 136 | * Interval: 0.5sec Threshold: 0.0625s |
5d8b34fd TG |
137 | */ |
138 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
35c35d1a | 139 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) |
5d8b34fd | 140 | |
8cf4e750 | 141 | static void clocksource_unstable(struct clocksource *cs, int64_t delta) |
5d8b34fd | 142 | { |
5d8b34fd TG |
143 | printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n", |
144 | cs->name, delta); | |
145 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); | |
c55c87c8 MS |
146 | cs->flags |= CLOCK_SOURCE_UNSTABLE; |
147 | schedule_work(&watchdog_work); | |
5d8b34fd TG |
148 | } |
149 | ||
150 | static void clocksource_watchdog(unsigned long data) | |
151 | { | |
c55c87c8 | 152 | struct clocksource *cs; |
5d8b34fd TG |
153 | cycle_t csnow, wdnow; |
154 | int64_t wd_nsec, cs_nsec; | |
c55c87c8 | 155 | int next_cpu; |
5d8b34fd TG |
156 | |
157 | spin_lock(&watchdog_lock); | |
fb63a0eb MS |
158 | if (!watchdog_running) |
159 | goto out; | |
5d8b34fd | 160 | |
8e19608e | 161 | wdnow = watchdog->read(watchdog); |
155ec602 MS |
162 | wd_nsec = clocksource_cyc2ns((wdnow - watchdog_last) & watchdog->mask, |
163 | watchdog->mult, watchdog->shift); | |
5d8b34fd TG |
164 | watchdog_last = wdnow; |
165 | ||
c55c87c8 MS |
166 | list_for_each_entry(cs, &watchdog_list, wd_list) { |
167 | ||
168 | /* Clocksource already marked unstable? */ | |
169 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) | |
170 | continue; | |
171 | ||
8e19608e | 172 | csnow = cs->read(cs); |
b52f52a0 | 173 | |
8cf4e750 MS |
174 | /* Clocksource initialized ? */ |
175 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG)) { | |
176 | cs->flags |= CLOCK_SOURCE_WATCHDOG; | |
b52f52a0 TG |
177 | cs->wd_last = csnow; |
178 | continue; | |
179 | } | |
180 | ||
8cf4e750 | 181 | /* Check the deviation from the watchdog clocksource. */ |
155ec602 MS |
182 | cs_nsec = clocksource_cyc2ns((csnow - cs->wd_last) & |
183 | cs->mask, cs->mult, cs->shift); | |
8cf4e750 MS |
184 | cs->wd_last = csnow; |
185 | if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) { | |
186 | clocksource_unstable(cs, cs_nsec - wd_nsec); | |
187 | continue; | |
188 | } | |
189 | ||
190 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && | |
191 | (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
192 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
193 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
194 | /* | |
195 | * We just marked the clocksource as highres-capable, | |
196 | * notify the rest of the system as well so that we | |
197 | * transition into high-res mode: | |
198 | */ | |
199 | tick_clock_notify(); | |
5d8b34fd TG |
200 | } |
201 | } | |
202 | ||
c55c87c8 MS |
203 | /* |
204 | * Cycle through CPUs to check if the CPUs stay synchronized | |
205 | * to each other. | |
206 | */ | |
207 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); | |
208 | if (next_cpu >= nr_cpu_ids) | |
209 | next_cpu = cpumask_first(cpu_online_mask); | |
210 | watchdog_timer.expires += WATCHDOG_INTERVAL; | |
211 | add_timer_on(&watchdog_timer, next_cpu); | |
fb63a0eb | 212 | out: |
5d8b34fd TG |
213 | spin_unlock(&watchdog_lock); |
214 | } | |
0f8e8ef7 | 215 | |
fb63a0eb MS |
216 | static inline void clocksource_start_watchdog(void) |
217 | { | |
218 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) | |
219 | return; | |
c55c87c8 | 220 | INIT_WORK(&watchdog_work, clocksource_watchdog_work); |
fb63a0eb MS |
221 | init_timer(&watchdog_timer); |
222 | watchdog_timer.function = clocksource_watchdog; | |
223 | watchdog_last = watchdog->read(watchdog); | |
224 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; | |
225 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); | |
226 | watchdog_running = 1; | |
227 | } | |
228 | ||
229 | static inline void clocksource_stop_watchdog(void) | |
230 | { | |
231 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) | |
232 | return; | |
233 | del_timer(&watchdog_timer); | |
234 | watchdog_running = 0; | |
235 | } | |
236 | ||
0f8e8ef7 MS |
237 | static inline void clocksource_reset_watchdog(void) |
238 | { | |
239 | struct clocksource *cs; | |
240 | ||
241 | list_for_each_entry(cs, &watchdog_list, wd_list) | |
242 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
243 | } | |
244 | ||
b52f52a0 TG |
245 | static void clocksource_resume_watchdog(void) |
246 | { | |
0f8e8ef7 MS |
247 | unsigned long flags; |
248 | ||
249 | spin_lock_irqsave(&watchdog_lock, flags); | |
250 | clocksource_reset_watchdog(); | |
251 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
b52f52a0 TG |
252 | } |
253 | ||
fb63a0eb | 254 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
5d8b34fd | 255 | { |
5d8b34fd TG |
256 | unsigned long flags; |
257 | ||
258 | spin_lock_irqsave(&watchdog_lock, flags); | |
259 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
fb63a0eb | 260 | /* cs is a clocksource to be watched. */ |
5d8b34fd | 261 | list_add(&cs->wd_list, &watchdog_list); |
fb63a0eb | 262 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
948ac6d7 | 263 | } else { |
fb63a0eb | 264 | /* cs is a watchdog. */ |
948ac6d7 | 265 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
5d8b34fd | 266 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
fb63a0eb | 267 | /* Pick the best watchdog. */ |
5d8b34fd | 268 | if (!watchdog || cs->rating > watchdog->rating) { |
5d8b34fd | 269 | watchdog = cs; |
5d8b34fd | 270 | /* Reset watchdog cycles */ |
0f8e8ef7 | 271 | clocksource_reset_watchdog(); |
5d8b34fd TG |
272 | } |
273 | } | |
fb63a0eb MS |
274 | /* Check if the watchdog timer needs to be started. */ |
275 | clocksource_start_watchdog(); | |
5d8b34fd TG |
276 | spin_unlock_irqrestore(&watchdog_lock, flags); |
277 | } | |
fb63a0eb MS |
278 | |
279 | static void clocksource_dequeue_watchdog(struct clocksource *cs) | |
280 | { | |
281 | struct clocksource *tmp; | |
282 | unsigned long flags; | |
283 | ||
284 | spin_lock_irqsave(&watchdog_lock, flags); | |
285 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
286 | /* cs is a watched clocksource. */ | |
287 | list_del_init(&cs->wd_list); | |
288 | } else if (cs == watchdog) { | |
289 | /* Reset watchdog cycles */ | |
290 | clocksource_reset_watchdog(); | |
291 | /* Current watchdog is removed. Find an alternative. */ | |
292 | watchdog = NULL; | |
293 | list_for_each_entry(tmp, &clocksource_list, list) { | |
294 | if (tmp == cs || tmp->flags & CLOCK_SOURCE_MUST_VERIFY) | |
295 | continue; | |
296 | if (!watchdog || tmp->rating > watchdog->rating) | |
297 | watchdog = tmp; | |
298 | } | |
299 | } | |
300 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
301 | /* Check if the watchdog timer needs to be stopped. */ | |
302 | clocksource_stop_watchdog(); | |
303 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
304 | } | |
305 | ||
c55c87c8 MS |
306 | static void clocksource_watchdog_work(struct work_struct *work) |
307 | { | |
308 | struct clocksource *cs, *tmp; | |
309 | unsigned long flags; | |
6ea41d25 | 310 | LIST_HEAD(unstable); |
c55c87c8 MS |
311 | |
312 | spin_lock_irqsave(&watchdog_lock, flags); | |
313 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) | |
314 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { | |
315 | list_del_init(&cs->wd_list); | |
6ea41d25 | 316 | list_add(&cs->wd_list, &unstable); |
c55c87c8 MS |
317 | } |
318 | /* Check if the watchdog timer needs to be stopped. */ | |
319 | clocksource_stop_watchdog(); | |
6ea41d25 TG |
320 | spin_unlock_irqrestore(&watchdog_lock, flags); |
321 | ||
322 | /* Needs to be done outside of watchdog lock */ | |
323 | list_for_each_entry_safe(cs, tmp, &unstable, wd_list) { | |
324 | list_del_init(&cs->wd_list); | |
325 | clocksource_change_rating(cs, 0); | |
326 | } | |
c55c87c8 MS |
327 | } |
328 | ||
fb63a0eb MS |
329 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
330 | ||
331 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
5d8b34fd TG |
332 | { |
333 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
334 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
335 | } | |
b52f52a0 | 336 | |
fb63a0eb | 337 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
b52f52a0 | 338 | static inline void clocksource_resume_watchdog(void) { } |
fb63a0eb MS |
339 | |
340 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ | |
5d8b34fd | 341 | |
b52f52a0 TG |
342 | /** |
343 | * clocksource_resume - resume the clocksource(s) | |
344 | */ | |
345 | void clocksource_resume(void) | |
346 | { | |
2e197586 | 347 | struct clocksource *cs; |
b52f52a0 | 348 | |
75c5158f | 349 | mutex_lock(&clocksource_mutex); |
b52f52a0 | 350 | |
75c5158f | 351 | list_for_each_entry(cs, &clocksource_list, list) |
b52f52a0 TG |
352 | if (cs->resume) |
353 | cs->resume(); | |
b52f52a0 TG |
354 | |
355 | clocksource_resume_watchdog(); | |
356 | ||
75c5158f | 357 | mutex_unlock(&clocksource_mutex); |
b52f52a0 TG |
358 | } |
359 | ||
7c3078b6 JW |
360 | /** |
361 | * clocksource_touch_watchdog - Update watchdog | |
362 | * | |
363 | * Update the watchdog after exception contexts such as kgdb so as not | |
364 | * to incorrectly trip the watchdog. | |
365 | * | |
366 | */ | |
367 | void clocksource_touch_watchdog(void) | |
368 | { | |
369 | clocksource_resume_watchdog(); | |
370 | } | |
371 | ||
f1b82746 | 372 | #ifdef CONFIG_GENERIC_TIME |
734efb46 | 373 | |
75c5158f | 374 | static int finished_booting; |
734efb46 | 375 | |
376 | /** | |
f1b82746 | 377 | * clocksource_select - Select the best clocksource available |
734efb46 | 378 | * |
75c5158f | 379 | * Private function. Must hold clocksource_mutex when called. |
734efb46 | 380 | * |
92c7e002 TG |
381 | * Select the clocksource with the best rating, or the clocksource, |
382 | * which is selected by userspace override. | |
734efb46 | 383 | */ |
f1b82746 | 384 | static void clocksource_select(void) |
734efb46 | 385 | { |
f1b82746 | 386 | struct clocksource *best, *cs; |
5d8b34fd | 387 | |
75c5158f | 388 | if (!finished_booting || list_empty(&clocksource_list)) |
f1b82746 MS |
389 | return; |
390 | /* First clocksource on the list has the best rating. */ | |
391 | best = list_first_entry(&clocksource_list, struct clocksource, list); | |
392 | /* Check for the override clocksource. */ | |
393 | list_for_each_entry(cs, &clocksource_list, list) { | |
394 | if (strcmp(cs->name, override_name) != 0) | |
395 | continue; | |
396 | /* | |
397 | * Check to make sure we don't switch to a non-highres | |
398 | * capable clocksource if the tick code is in oneshot | |
399 | * mode (highres or nohz) | |
400 | */ | |
401 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && | |
402 | tick_oneshot_mode_active()) { | |
403 | /* Override clocksource cannot be used. */ | |
404 | printk(KERN_WARNING "Override clocksource %s is not " | |
405 | "HRT compatible. Cannot switch while in " | |
406 | "HRT/NOHZ mode\n", cs->name); | |
407 | override_name[0] = 0; | |
408 | } else | |
409 | /* Override clocksource can be used. */ | |
410 | best = cs; | |
411 | break; | |
412 | } | |
75c5158f MS |
413 | if (curr_clocksource != best) { |
414 | printk(KERN_INFO "Switching to clocksource %s\n", best->name); | |
415 | curr_clocksource = best; | |
416 | timekeeping_notify(curr_clocksource); | |
417 | } | |
f1b82746 | 418 | } |
734efb46 | 419 | |
75c5158f MS |
420 | /* |
421 | * clocksource_done_booting - Called near the end of core bootup | |
422 | * | |
423 | * Hack to avoid lots of clocksource churn at boot time. | |
424 | * We use fs_initcall because we want this to start before | |
425 | * device_initcall but after subsys_initcall. | |
426 | */ | |
427 | static int __init clocksource_done_booting(void) | |
428 | { | |
429 | finished_booting = 1; | |
430 | clocksource_select(); | |
431 | return 0; | |
432 | } | |
433 | fs_initcall(clocksource_done_booting); | |
434 | ||
f1b82746 | 435 | #else /* CONFIG_GENERIC_TIME */ |
734efb46 | 436 | |
75c5158f | 437 | static inline void clocksource_select(void) { } |
5d8b34fd | 438 | |
f1b82746 | 439 | #endif |
734efb46 | 440 | |
92c7e002 TG |
441 | /* |
442 | * Enqueue the clocksource sorted by rating | |
734efb46 | 443 | */ |
f1b82746 | 444 | static void clocksource_enqueue(struct clocksource *cs) |
734efb46 | 445 | { |
f1b82746 MS |
446 | struct list_head *entry = &clocksource_list; |
447 | struct clocksource *tmp; | |
92c7e002 | 448 | |
f1b82746 | 449 | list_for_each_entry(tmp, &clocksource_list, list) |
92c7e002 | 450 | /* Keep track of the place, where to insert */ |
f1b82746 MS |
451 | if (tmp->rating >= cs->rating) |
452 | entry = &tmp->list; | |
453 | list_add(&cs->list, entry); | |
734efb46 | 454 | } |
455 | ||
456 | /** | |
a2752549 | 457 | * clocksource_register - Used to install new clocksources |
734efb46 | 458 | * @t: clocksource to be registered |
459 | * | |
460 | * Returns -EBUSY if registration fails, zero otherwise. | |
461 | */ | |
f1b82746 | 462 | int clocksource_register(struct clocksource *cs) |
734efb46 | 463 | { |
75c5158f | 464 | mutex_lock(&clocksource_mutex); |
f1b82746 MS |
465 | clocksource_enqueue(cs); |
466 | clocksource_select(); | |
fb63a0eb | 467 | clocksource_enqueue_watchdog(cs); |
75c5158f | 468 | mutex_unlock(&clocksource_mutex); |
f1b82746 | 469 | return 0; |
734efb46 | 470 | } |
a2752549 | 471 | EXPORT_SYMBOL(clocksource_register); |
734efb46 | 472 | |
473 | /** | |
92c7e002 | 474 | * clocksource_change_rating - Change the rating of a registered clocksource |
734efb46 | 475 | */ |
92c7e002 | 476 | void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb46 | 477 | { |
75c5158f | 478 | mutex_lock(&clocksource_mutex); |
92c7e002 | 479 | list_del(&cs->list); |
5d8b34fd | 480 | cs->rating = rating; |
92c7e002 | 481 | clocksource_enqueue(cs); |
f1b82746 | 482 | clocksource_select(); |
75c5158f | 483 | mutex_unlock(&clocksource_mutex); |
734efb46 | 484 | } |
fb63a0eb | 485 | EXPORT_SYMBOL(clocksource_change_rating); |
734efb46 | 486 | |
4713e22c TG |
487 | /** |
488 | * clocksource_unregister - remove a registered clocksource | |
489 | */ | |
490 | void clocksource_unregister(struct clocksource *cs) | |
491 | { | |
75c5158f | 492 | mutex_lock(&clocksource_mutex); |
fb63a0eb | 493 | clocksource_dequeue_watchdog(cs); |
4713e22c | 494 | list_del(&cs->list); |
f1b82746 | 495 | clocksource_select(); |
75c5158f | 496 | mutex_unlock(&clocksource_mutex); |
4713e22c | 497 | } |
fb63a0eb | 498 | EXPORT_SYMBOL(clocksource_unregister); |
4713e22c | 499 | |
2b013700 | 500 | #ifdef CONFIG_SYSFS |
734efb46 | 501 | /** |
502 | * sysfs_show_current_clocksources - sysfs interface for current clocksource | |
503 | * @dev: unused | |
504 | * @buf: char buffer to be filled with clocksource list | |
505 | * | |
506 | * Provides sysfs interface for listing current clocksource. | |
507 | */ | |
508 | static ssize_t | |
4a0b2b4d AK |
509 | sysfs_show_current_clocksources(struct sys_device *dev, |
510 | struct sysdev_attribute *attr, char *buf) | |
734efb46 | 511 | { |
5e2cb101 | 512 | ssize_t count = 0; |
734efb46 | 513 | |
75c5158f | 514 | mutex_lock(&clocksource_mutex); |
5e2cb101 | 515 | count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); |
75c5158f | 516 | mutex_unlock(&clocksource_mutex); |
734efb46 | 517 | |
5e2cb101 | 518 | return count; |
734efb46 | 519 | } |
520 | ||
521 | /** | |
522 | * sysfs_override_clocksource - interface for manually overriding clocksource | |
523 | * @dev: unused | |
524 | * @buf: name of override clocksource | |
525 | * @count: length of buffer | |
526 | * | |
527 | * Takes input from sysfs interface for manually overriding the default | |
528 | * clocksource selction. | |
529 | */ | |
530 | static ssize_t sysfs_override_clocksource(struct sys_device *dev, | |
4a0b2b4d | 531 | struct sysdev_attribute *attr, |
734efb46 | 532 | const char *buf, size_t count) |
533 | { | |
534 | size_t ret = count; | |
92c7e002 | 535 | |
734efb46 | 536 | /* strings from sysfs write are not 0 terminated! */ |
537 | if (count >= sizeof(override_name)) | |
538 | return -EINVAL; | |
539 | ||
540 | /* strip of \n: */ | |
541 | if (buf[count-1] == '\n') | |
542 | count--; | |
734efb46 | 543 | |
75c5158f | 544 | mutex_lock(&clocksource_mutex); |
734efb46 | 545 | |
92c7e002 TG |
546 | if (count > 0) |
547 | memcpy(override_name, buf, count); | |
734efb46 | 548 | override_name[count] = 0; |
f1b82746 | 549 | clocksource_select(); |
734efb46 | 550 | |
75c5158f | 551 | mutex_unlock(&clocksource_mutex); |
734efb46 | 552 | |
553 | return ret; | |
554 | } | |
555 | ||
556 | /** | |
557 | * sysfs_show_available_clocksources - sysfs interface for listing clocksource | |
558 | * @dev: unused | |
559 | * @buf: char buffer to be filled with clocksource list | |
560 | * | |
561 | * Provides sysfs interface for listing registered clocksources | |
562 | */ | |
563 | static ssize_t | |
4a0b2b4d AK |
564 | sysfs_show_available_clocksources(struct sys_device *dev, |
565 | struct sysdev_attribute *attr, | |
566 | char *buf) | |
734efb46 | 567 | { |
2e197586 | 568 | struct clocksource *src; |
5e2cb101 | 569 | ssize_t count = 0; |
734efb46 | 570 | |
75c5158f | 571 | mutex_lock(&clocksource_mutex); |
2e197586 | 572 | list_for_each_entry(src, &clocksource_list, list) { |
cd6d95d8 TG |
573 | /* |
574 | * Don't show non-HRES clocksource if the tick code is | |
575 | * in one shot mode (highres=on or nohz=on) | |
576 | */ | |
577 | if (!tick_oneshot_mode_active() || | |
578 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) | |
3f68535a | 579 | count += snprintf(buf + count, |
5e2cb101 MX |
580 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), |
581 | "%s ", src->name); | |
734efb46 | 582 | } |
75c5158f | 583 | mutex_unlock(&clocksource_mutex); |
734efb46 | 584 | |
5e2cb101 MX |
585 | count += snprintf(buf + count, |
586 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); | |
734efb46 | 587 | |
5e2cb101 | 588 | return count; |
734efb46 | 589 | } |
590 | ||
591 | /* | |
592 | * Sysfs setup bits: | |
593 | */ | |
4f95f81a | 594 | static SYSDEV_ATTR(current_clocksource, 0644, sysfs_show_current_clocksources, |
f5f1a24a | 595 | sysfs_override_clocksource); |
734efb46 | 596 | |
4f95f81a | 597 | static SYSDEV_ATTR(available_clocksource, 0444, |
f5f1a24a | 598 | sysfs_show_available_clocksources, NULL); |
734efb46 | 599 | |
600 | static struct sysdev_class clocksource_sysclass = { | |
af5ca3f4 | 601 | .name = "clocksource", |
734efb46 | 602 | }; |
603 | ||
604 | static struct sys_device device_clocksource = { | |
605 | .id = 0, | |
606 | .cls = &clocksource_sysclass, | |
607 | }; | |
608 | ||
ad596171 | 609 | static int __init init_clocksource_sysfs(void) |
734efb46 | 610 | { |
611 | int error = sysdev_class_register(&clocksource_sysclass); | |
612 | ||
613 | if (!error) | |
614 | error = sysdev_register(&device_clocksource); | |
615 | if (!error) | |
616 | error = sysdev_create_file( | |
617 | &device_clocksource, | |
618 | &attr_current_clocksource); | |
619 | if (!error) | |
620 | error = sysdev_create_file( | |
621 | &device_clocksource, | |
622 | &attr_available_clocksource); | |
623 | return error; | |
624 | } | |
625 | ||
626 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 627 | #endif /* CONFIG_SYSFS */ |
734efb46 | 628 | |
629 | /** | |
630 | * boot_override_clocksource - boot clock override | |
631 | * @str: override name | |
632 | * | |
633 | * Takes a clocksource= boot argument and uses it | |
634 | * as the clocksource override name. | |
635 | */ | |
636 | static int __init boot_override_clocksource(char* str) | |
637 | { | |
75c5158f | 638 | mutex_lock(&clocksource_mutex); |
734efb46 | 639 | if (str) |
640 | strlcpy(override_name, str, sizeof(override_name)); | |
75c5158f | 641 | mutex_unlock(&clocksource_mutex); |
734efb46 | 642 | return 1; |
643 | } | |
644 | ||
645 | __setup("clocksource=", boot_override_clocksource); | |
646 | ||
647 | /** | |
648 | * boot_override_clock - Compatibility layer for deprecated boot option | |
649 | * @str: override name | |
650 | * | |
651 | * DEPRECATED! Takes a clock= boot argument and uses it | |
652 | * as the clocksource override name | |
653 | */ | |
654 | static int __init boot_override_clock(char* str) | |
655 | { | |
5d0cf410 | 656 | if (!strcmp(str, "pmtmr")) { |
657 | printk("Warning: clock=pmtmr is deprecated. " | |
658 | "Use clocksource=acpi_pm.\n"); | |
659 | return boot_override_clocksource("acpi_pm"); | |
660 | } | |
661 | printk("Warning! clock= boot option is deprecated. " | |
662 | "Use clocksource=xyz\n"); | |
734efb46 | 663 | return boot_override_clocksource(str); |
664 | } | |
665 | ||
666 | __setup("clock=", boot_override_clock); |