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 | 133 | static void clocksource_watchdog_work(struct work_struct *work); |
d0981a1b | 134 | static void __clocksource_change_rating(struct clocksource *cs, int rating); |
c55c87c8 | 135 | |
5d8b34fd | 136 | /* |
35c35d1a | 137 | * Interval: 0.5sec Threshold: 0.0625s |
5d8b34fd TG |
138 | */ |
139 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
35c35d1a | 140 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) |
5d8b34fd | 141 | |
8cf4e750 | 142 | static void clocksource_unstable(struct clocksource *cs, int64_t delta) |
5d8b34fd | 143 | { |
5d8b34fd TG |
144 | printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n", |
145 | cs->name, delta); | |
146 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); | |
c55c87c8 MS |
147 | cs->flags |= CLOCK_SOURCE_UNSTABLE; |
148 | schedule_work(&watchdog_work); | |
5d8b34fd TG |
149 | } |
150 | ||
151 | static void clocksource_watchdog(unsigned long data) | |
152 | { | |
c55c87c8 | 153 | struct clocksource *cs; |
5d8b34fd TG |
154 | cycle_t csnow, wdnow; |
155 | int64_t wd_nsec, cs_nsec; | |
c55c87c8 | 156 | int next_cpu; |
5d8b34fd TG |
157 | |
158 | spin_lock(&watchdog_lock); | |
fb63a0eb MS |
159 | if (!watchdog_running) |
160 | goto out; | |
5d8b34fd | 161 | |
8e19608e | 162 | wdnow = watchdog->read(watchdog); |
155ec602 MS |
163 | wd_nsec = clocksource_cyc2ns((wdnow - watchdog_last) & watchdog->mask, |
164 | watchdog->mult, watchdog->shift); | |
5d8b34fd TG |
165 | watchdog_last = wdnow; |
166 | ||
c55c87c8 MS |
167 | list_for_each_entry(cs, &watchdog_list, wd_list) { |
168 | ||
169 | /* Clocksource already marked unstable? */ | |
170 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) | |
171 | continue; | |
172 | ||
8e19608e | 173 | csnow = cs->read(cs); |
b52f52a0 | 174 | |
8cf4e750 MS |
175 | /* Clocksource initialized ? */ |
176 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG)) { | |
177 | cs->flags |= CLOCK_SOURCE_WATCHDOG; | |
b52f52a0 TG |
178 | cs->wd_last = csnow; |
179 | continue; | |
180 | } | |
181 | ||
8cf4e750 | 182 | /* Check the deviation from the watchdog clocksource. */ |
155ec602 MS |
183 | cs_nsec = clocksource_cyc2ns((csnow - cs->wd_last) & |
184 | cs->mask, cs->mult, cs->shift); | |
8cf4e750 MS |
185 | cs->wd_last = csnow; |
186 | if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) { | |
187 | clocksource_unstable(cs, cs_nsec - wd_nsec); | |
188 | continue; | |
189 | } | |
190 | ||
191 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && | |
192 | (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
193 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
194 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
195 | /* | |
196 | * We just marked the clocksource as highres-capable, | |
197 | * notify the rest of the system as well so that we | |
198 | * transition into high-res mode: | |
199 | */ | |
200 | tick_clock_notify(); | |
5d8b34fd TG |
201 | } |
202 | } | |
203 | ||
c55c87c8 MS |
204 | /* |
205 | * Cycle through CPUs to check if the CPUs stay synchronized | |
206 | * to each other. | |
207 | */ | |
208 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); | |
209 | if (next_cpu >= nr_cpu_ids) | |
210 | next_cpu = cpumask_first(cpu_online_mask); | |
211 | watchdog_timer.expires += WATCHDOG_INTERVAL; | |
212 | add_timer_on(&watchdog_timer, next_cpu); | |
fb63a0eb | 213 | out: |
5d8b34fd TG |
214 | spin_unlock(&watchdog_lock); |
215 | } | |
0f8e8ef7 | 216 | |
fb63a0eb MS |
217 | static inline void clocksource_start_watchdog(void) |
218 | { | |
219 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) | |
220 | return; | |
c55c87c8 | 221 | INIT_WORK(&watchdog_work, clocksource_watchdog_work); |
fb63a0eb MS |
222 | init_timer(&watchdog_timer); |
223 | watchdog_timer.function = clocksource_watchdog; | |
224 | watchdog_last = watchdog->read(watchdog); | |
225 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; | |
226 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); | |
227 | watchdog_running = 1; | |
228 | } | |
229 | ||
230 | static inline void clocksource_stop_watchdog(void) | |
231 | { | |
232 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) | |
233 | return; | |
234 | del_timer(&watchdog_timer); | |
235 | watchdog_running = 0; | |
236 | } | |
237 | ||
0f8e8ef7 MS |
238 | static inline void clocksource_reset_watchdog(void) |
239 | { | |
240 | struct clocksource *cs; | |
241 | ||
242 | list_for_each_entry(cs, &watchdog_list, wd_list) | |
243 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
244 | } | |
245 | ||
b52f52a0 TG |
246 | static void clocksource_resume_watchdog(void) |
247 | { | |
0f8e8ef7 MS |
248 | unsigned long flags; |
249 | ||
250 | spin_lock_irqsave(&watchdog_lock, flags); | |
251 | clocksource_reset_watchdog(); | |
252 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
b52f52a0 TG |
253 | } |
254 | ||
fb63a0eb | 255 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
5d8b34fd | 256 | { |
5d8b34fd TG |
257 | unsigned long flags; |
258 | ||
259 | spin_lock_irqsave(&watchdog_lock, flags); | |
260 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
fb63a0eb | 261 | /* cs is a clocksource to be watched. */ |
5d8b34fd | 262 | list_add(&cs->wd_list, &watchdog_list); |
fb63a0eb | 263 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
948ac6d7 | 264 | } else { |
fb63a0eb | 265 | /* cs is a watchdog. */ |
948ac6d7 | 266 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
5d8b34fd | 267 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
fb63a0eb | 268 | /* Pick the best watchdog. */ |
5d8b34fd | 269 | if (!watchdog || cs->rating > watchdog->rating) { |
5d8b34fd | 270 | watchdog = cs; |
5d8b34fd | 271 | /* Reset watchdog cycles */ |
0f8e8ef7 | 272 | clocksource_reset_watchdog(); |
5d8b34fd TG |
273 | } |
274 | } | |
fb63a0eb MS |
275 | /* Check if the watchdog timer needs to be started. */ |
276 | clocksource_start_watchdog(); | |
5d8b34fd TG |
277 | spin_unlock_irqrestore(&watchdog_lock, flags); |
278 | } | |
fb63a0eb MS |
279 | |
280 | static void clocksource_dequeue_watchdog(struct clocksource *cs) | |
281 | { | |
282 | struct clocksource *tmp; | |
283 | unsigned long flags; | |
284 | ||
285 | spin_lock_irqsave(&watchdog_lock, flags); | |
286 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
287 | /* cs is a watched clocksource. */ | |
288 | list_del_init(&cs->wd_list); | |
289 | } else if (cs == watchdog) { | |
290 | /* Reset watchdog cycles */ | |
291 | clocksource_reset_watchdog(); | |
292 | /* Current watchdog is removed. Find an alternative. */ | |
293 | watchdog = NULL; | |
294 | list_for_each_entry(tmp, &clocksource_list, list) { | |
295 | if (tmp == cs || tmp->flags & CLOCK_SOURCE_MUST_VERIFY) | |
296 | continue; | |
297 | if (!watchdog || tmp->rating > watchdog->rating) | |
298 | watchdog = tmp; | |
299 | } | |
300 | } | |
301 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
302 | /* Check if the watchdog timer needs to be stopped. */ | |
303 | clocksource_stop_watchdog(); | |
304 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
305 | } | |
306 | ||
c55c87c8 MS |
307 | static void clocksource_watchdog_work(struct work_struct *work) |
308 | { | |
309 | struct clocksource *cs, *tmp; | |
310 | unsigned long flags; | |
6ea41d25 | 311 | LIST_HEAD(unstable); |
c55c87c8 | 312 | |
d0981a1b | 313 | mutex_lock(&clocksource_mutex); |
c55c87c8 MS |
314 | spin_lock_irqsave(&watchdog_lock, flags); |
315 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) | |
316 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { | |
317 | list_del_init(&cs->wd_list); | |
6ea41d25 | 318 | list_add(&cs->wd_list, &unstable); |
c55c87c8 MS |
319 | } |
320 | /* Check if the watchdog timer needs to be stopped. */ | |
321 | clocksource_stop_watchdog(); | |
6ea41d25 TG |
322 | spin_unlock_irqrestore(&watchdog_lock, flags); |
323 | ||
324 | /* Needs to be done outside of watchdog lock */ | |
325 | list_for_each_entry_safe(cs, tmp, &unstable, wd_list) { | |
326 | list_del_init(&cs->wd_list); | |
d0981a1b | 327 | __clocksource_change_rating(cs, 0); |
6ea41d25 | 328 | } |
d0981a1b | 329 | mutex_unlock(&clocksource_mutex); |
c55c87c8 MS |
330 | } |
331 | ||
fb63a0eb MS |
332 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
333 | ||
334 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
5d8b34fd TG |
335 | { |
336 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
337 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
338 | } | |
b52f52a0 | 339 | |
fb63a0eb | 340 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
b52f52a0 | 341 | static inline void clocksource_resume_watchdog(void) { } |
fb63a0eb MS |
342 | |
343 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ | |
5d8b34fd | 344 | |
b52f52a0 TG |
345 | /** |
346 | * clocksource_resume - resume the clocksource(s) | |
347 | */ | |
348 | void clocksource_resume(void) | |
349 | { | |
2e197586 | 350 | struct clocksource *cs; |
b52f52a0 | 351 | |
75c5158f | 352 | mutex_lock(&clocksource_mutex); |
b52f52a0 | 353 | |
75c5158f | 354 | list_for_each_entry(cs, &clocksource_list, list) |
b52f52a0 TG |
355 | if (cs->resume) |
356 | cs->resume(); | |
b52f52a0 TG |
357 | |
358 | clocksource_resume_watchdog(); | |
359 | ||
75c5158f | 360 | mutex_unlock(&clocksource_mutex); |
b52f52a0 TG |
361 | } |
362 | ||
7c3078b6 JW |
363 | /** |
364 | * clocksource_touch_watchdog - Update watchdog | |
365 | * | |
366 | * Update the watchdog after exception contexts such as kgdb so as not | |
367 | * to incorrectly trip the watchdog. | |
368 | * | |
369 | */ | |
370 | void clocksource_touch_watchdog(void) | |
371 | { | |
372 | clocksource_resume_watchdog(); | |
373 | } | |
374 | ||
f1b82746 | 375 | #ifdef CONFIG_GENERIC_TIME |
734efb46 | 376 | |
75c5158f | 377 | static int finished_booting; |
734efb46 | 378 | |
379 | /** | |
f1b82746 | 380 | * clocksource_select - Select the best clocksource available |
734efb46 | 381 | * |
75c5158f | 382 | * Private function. Must hold clocksource_mutex when called. |
734efb46 | 383 | * |
92c7e002 TG |
384 | * Select the clocksource with the best rating, or the clocksource, |
385 | * which is selected by userspace override. | |
734efb46 | 386 | */ |
f1b82746 | 387 | static void clocksource_select(void) |
734efb46 | 388 | { |
f1b82746 | 389 | struct clocksource *best, *cs; |
5d8b34fd | 390 | |
75c5158f | 391 | if (!finished_booting || list_empty(&clocksource_list)) |
f1b82746 MS |
392 | return; |
393 | /* First clocksource on the list has the best rating. */ | |
394 | best = list_first_entry(&clocksource_list, struct clocksource, list); | |
395 | /* Check for the override clocksource. */ | |
396 | list_for_each_entry(cs, &clocksource_list, list) { | |
397 | if (strcmp(cs->name, override_name) != 0) | |
398 | continue; | |
399 | /* | |
400 | * Check to make sure we don't switch to a non-highres | |
401 | * capable clocksource if the tick code is in oneshot | |
402 | * mode (highres or nohz) | |
403 | */ | |
404 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && | |
405 | tick_oneshot_mode_active()) { | |
406 | /* Override clocksource cannot be used. */ | |
407 | printk(KERN_WARNING "Override clocksource %s is not " | |
408 | "HRT compatible. Cannot switch while in " | |
409 | "HRT/NOHZ mode\n", cs->name); | |
410 | override_name[0] = 0; | |
411 | } else | |
412 | /* Override clocksource can be used. */ | |
413 | best = cs; | |
414 | break; | |
415 | } | |
75c5158f MS |
416 | if (curr_clocksource != best) { |
417 | printk(KERN_INFO "Switching to clocksource %s\n", best->name); | |
418 | curr_clocksource = best; | |
419 | timekeeping_notify(curr_clocksource); | |
420 | } | |
f1b82746 | 421 | } |
734efb46 | 422 | |
75c5158f MS |
423 | /* |
424 | * clocksource_done_booting - Called near the end of core bootup | |
425 | * | |
426 | * Hack to avoid lots of clocksource churn at boot time. | |
427 | * We use fs_initcall because we want this to start before | |
428 | * device_initcall but after subsys_initcall. | |
429 | */ | |
430 | static int __init clocksource_done_booting(void) | |
431 | { | |
432 | finished_booting = 1; | |
433 | clocksource_select(); | |
434 | return 0; | |
435 | } | |
436 | fs_initcall(clocksource_done_booting); | |
437 | ||
f1b82746 | 438 | #else /* CONFIG_GENERIC_TIME */ |
734efb46 | 439 | |
75c5158f | 440 | static inline void clocksource_select(void) { } |
5d8b34fd | 441 | |
f1b82746 | 442 | #endif |
734efb46 | 443 | |
92c7e002 TG |
444 | /* |
445 | * Enqueue the clocksource sorted by rating | |
734efb46 | 446 | */ |
f1b82746 | 447 | static void clocksource_enqueue(struct clocksource *cs) |
734efb46 | 448 | { |
f1b82746 MS |
449 | struct list_head *entry = &clocksource_list; |
450 | struct clocksource *tmp; | |
92c7e002 | 451 | |
f1b82746 | 452 | list_for_each_entry(tmp, &clocksource_list, list) |
92c7e002 | 453 | /* Keep track of the place, where to insert */ |
f1b82746 MS |
454 | if (tmp->rating >= cs->rating) |
455 | entry = &tmp->list; | |
456 | list_add(&cs->list, entry); | |
734efb46 | 457 | } |
458 | ||
459 | /** | |
a2752549 | 460 | * clocksource_register - Used to install new clocksources |
734efb46 | 461 | * @t: clocksource to be registered |
462 | * | |
463 | * Returns -EBUSY if registration fails, zero otherwise. | |
464 | */ | |
f1b82746 | 465 | int clocksource_register(struct clocksource *cs) |
734efb46 | 466 | { |
75c5158f | 467 | mutex_lock(&clocksource_mutex); |
f1b82746 MS |
468 | clocksource_enqueue(cs); |
469 | clocksource_select(); | |
fb63a0eb | 470 | clocksource_enqueue_watchdog(cs); |
75c5158f | 471 | mutex_unlock(&clocksource_mutex); |
f1b82746 | 472 | return 0; |
734efb46 | 473 | } |
a2752549 | 474 | EXPORT_SYMBOL(clocksource_register); |
734efb46 | 475 | |
d0981a1b TG |
476 | static void __clocksource_change_rating(struct clocksource *cs, int rating) |
477 | { | |
478 | list_del(&cs->list); | |
479 | cs->rating = rating; | |
480 | clocksource_enqueue(cs); | |
481 | clocksource_select(); | |
482 | } | |
483 | ||
734efb46 | 484 | /** |
92c7e002 | 485 | * clocksource_change_rating - Change the rating of a registered clocksource |
734efb46 | 486 | */ |
92c7e002 | 487 | void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb46 | 488 | { |
75c5158f | 489 | mutex_lock(&clocksource_mutex); |
d0981a1b | 490 | __clocksource_change_rating(cs, rating); |
75c5158f | 491 | mutex_unlock(&clocksource_mutex); |
734efb46 | 492 | } |
fb63a0eb | 493 | EXPORT_SYMBOL(clocksource_change_rating); |
734efb46 | 494 | |
4713e22c TG |
495 | /** |
496 | * clocksource_unregister - remove a registered clocksource | |
497 | */ | |
498 | void clocksource_unregister(struct clocksource *cs) | |
499 | { | |
75c5158f | 500 | mutex_lock(&clocksource_mutex); |
fb63a0eb | 501 | clocksource_dequeue_watchdog(cs); |
4713e22c | 502 | list_del(&cs->list); |
f1b82746 | 503 | clocksource_select(); |
75c5158f | 504 | mutex_unlock(&clocksource_mutex); |
4713e22c | 505 | } |
fb63a0eb | 506 | EXPORT_SYMBOL(clocksource_unregister); |
4713e22c | 507 | |
2b013700 | 508 | #ifdef CONFIG_SYSFS |
734efb46 | 509 | /** |
510 | * sysfs_show_current_clocksources - sysfs interface for current clocksource | |
511 | * @dev: unused | |
512 | * @buf: char buffer to be filled with clocksource list | |
513 | * | |
514 | * Provides sysfs interface for listing current clocksource. | |
515 | */ | |
516 | static ssize_t | |
4a0b2b4d AK |
517 | sysfs_show_current_clocksources(struct sys_device *dev, |
518 | struct sysdev_attribute *attr, char *buf) | |
734efb46 | 519 | { |
5e2cb101 | 520 | ssize_t count = 0; |
734efb46 | 521 | |
75c5158f | 522 | mutex_lock(&clocksource_mutex); |
5e2cb101 | 523 | count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); |
75c5158f | 524 | mutex_unlock(&clocksource_mutex); |
734efb46 | 525 | |
5e2cb101 | 526 | return count; |
734efb46 | 527 | } |
528 | ||
529 | /** | |
530 | * sysfs_override_clocksource - interface for manually overriding clocksource | |
531 | * @dev: unused | |
532 | * @buf: name of override clocksource | |
533 | * @count: length of buffer | |
534 | * | |
535 | * Takes input from sysfs interface for manually overriding the default | |
536 | * clocksource selction. | |
537 | */ | |
538 | static ssize_t sysfs_override_clocksource(struct sys_device *dev, | |
4a0b2b4d | 539 | struct sysdev_attribute *attr, |
734efb46 | 540 | const char *buf, size_t count) |
541 | { | |
542 | size_t ret = count; | |
92c7e002 | 543 | |
734efb46 | 544 | /* strings from sysfs write are not 0 terminated! */ |
545 | if (count >= sizeof(override_name)) | |
546 | return -EINVAL; | |
547 | ||
548 | /* strip of \n: */ | |
549 | if (buf[count-1] == '\n') | |
550 | count--; | |
734efb46 | 551 | |
75c5158f | 552 | mutex_lock(&clocksource_mutex); |
734efb46 | 553 | |
92c7e002 TG |
554 | if (count > 0) |
555 | memcpy(override_name, buf, count); | |
734efb46 | 556 | override_name[count] = 0; |
f1b82746 | 557 | clocksource_select(); |
734efb46 | 558 | |
75c5158f | 559 | mutex_unlock(&clocksource_mutex); |
734efb46 | 560 | |
561 | return ret; | |
562 | } | |
563 | ||
564 | /** | |
565 | * sysfs_show_available_clocksources - sysfs interface for listing clocksource | |
566 | * @dev: unused | |
567 | * @buf: char buffer to be filled with clocksource list | |
568 | * | |
569 | * Provides sysfs interface for listing registered clocksources | |
570 | */ | |
571 | static ssize_t | |
4a0b2b4d AK |
572 | sysfs_show_available_clocksources(struct sys_device *dev, |
573 | struct sysdev_attribute *attr, | |
574 | char *buf) | |
734efb46 | 575 | { |
2e197586 | 576 | struct clocksource *src; |
5e2cb101 | 577 | ssize_t count = 0; |
734efb46 | 578 | |
75c5158f | 579 | mutex_lock(&clocksource_mutex); |
2e197586 | 580 | list_for_each_entry(src, &clocksource_list, list) { |
cd6d95d8 TG |
581 | /* |
582 | * Don't show non-HRES clocksource if the tick code is | |
583 | * in one shot mode (highres=on or nohz=on) | |
584 | */ | |
585 | if (!tick_oneshot_mode_active() || | |
586 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) | |
3f68535a | 587 | count += snprintf(buf + count, |
5e2cb101 MX |
588 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), |
589 | "%s ", src->name); | |
734efb46 | 590 | } |
75c5158f | 591 | mutex_unlock(&clocksource_mutex); |
734efb46 | 592 | |
5e2cb101 MX |
593 | count += snprintf(buf + count, |
594 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); | |
734efb46 | 595 | |
5e2cb101 | 596 | return count; |
734efb46 | 597 | } |
598 | ||
599 | /* | |
600 | * Sysfs setup bits: | |
601 | */ | |
4f95f81a | 602 | static SYSDEV_ATTR(current_clocksource, 0644, sysfs_show_current_clocksources, |
f5f1a24a | 603 | sysfs_override_clocksource); |
734efb46 | 604 | |
4f95f81a | 605 | static SYSDEV_ATTR(available_clocksource, 0444, |
f5f1a24a | 606 | sysfs_show_available_clocksources, NULL); |
734efb46 | 607 | |
608 | static struct sysdev_class clocksource_sysclass = { | |
af5ca3f4 | 609 | .name = "clocksource", |
734efb46 | 610 | }; |
611 | ||
612 | static struct sys_device device_clocksource = { | |
613 | .id = 0, | |
614 | .cls = &clocksource_sysclass, | |
615 | }; | |
616 | ||
ad596171 | 617 | static int __init init_clocksource_sysfs(void) |
734efb46 | 618 | { |
619 | int error = sysdev_class_register(&clocksource_sysclass); | |
620 | ||
621 | if (!error) | |
622 | error = sysdev_register(&device_clocksource); | |
623 | if (!error) | |
624 | error = sysdev_create_file( | |
625 | &device_clocksource, | |
626 | &attr_current_clocksource); | |
627 | if (!error) | |
628 | error = sysdev_create_file( | |
629 | &device_clocksource, | |
630 | &attr_available_clocksource); | |
631 | return error; | |
632 | } | |
633 | ||
634 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 635 | #endif /* CONFIG_SYSFS */ |
734efb46 | 636 | |
637 | /** | |
638 | * boot_override_clocksource - boot clock override | |
639 | * @str: override name | |
640 | * | |
641 | * Takes a clocksource= boot argument and uses it | |
642 | * as the clocksource override name. | |
643 | */ | |
644 | static int __init boot_override_clocksource(char* str) | |
645 | { | |
75c5158f | 646 | mutex_lock(&clocksource_mutex); |
734efb46 | 647 | if (str) |
648 | strlcpy(override_name, str, sizeof(override_name)); | |
75c5158f | 649 | mutex_unlock(&clocksource_mutex); |
734efb46 | 650 | return 1; |
651 | } | |
652 | ||
653 | __setup("clocksource=", boot_override_clocksource); | |
654 | ||
655 | /** | |
656 | * boot_override_clock - Compatibility layer for deprecated boot option | |
657 | * @str: override name | |
658 | * | |
659 | * DEPRECATED! Takes a clock= boot argument and uses it | |
660 | * as the clocksource override name | |
661 | */ | |
662 | static int __init boot_override_clock(char* str) | |
663 | { | |
5d0cf410 | 664 | if (!strcmp(str, "pmtmr")) { |
665 | printk("Warning: clock=pmtmr is deprecated. " | |
666 | "Use clocksource=acpi_pm.\n"); | |
667 | return boot_override_clocksource("acpi_pm"); | |
668 | } | |
669 | printk("Warning! clock= boot option is deprecated. " | |
670 | "Use clocksource=xyz\n"); | |
734efb46 | 671 | return boot_override_clocksource(str); |
672 | } | |
673 | ||
674 | __setup("clock=", boot_override_clock); |