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734efb46 JS |
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 JS |
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> |
01548f4d | 32 | #include <linux/kthread.h> |
734efb46 | 33 | |
a038a353 PO |
34 | void 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 | } | |
42 | EXPORT_SYMBOL(timecounter_init); | |
43 | ||
44 | /** | |
45 | * timecounter_read_delta - get nanoseconds since last call of this function | |
46 | * @tc: Pointer to time counter | |
47 | * | |
48 | * When the underlying cycle counter runs over, this will be handled | |
49 | * correctly as long as it does not run over more than once between | |
50 | * calls. | |
51 | * | |
52 | * The first call to this function for a new time counter initializes | |
53 | * the time tracking and returns an undefined result. | |
54 | */ | |
55 | static u64 timecounter_read_delta(struct timecounter *tc) | |
56 | { | |
57 | cycle_t cycle_now, cycle_delta; | |
58 | u64 ns_offset; | |
59 | ||
60 | /* read cycle counter: */ | |
61 | cycle_now = tc->cc->read(tc->cc); | |
62 | ||
63 | /* calculate the delta since the last timecounter_read_delta(): */ | |
64 | cycle_delta = (cycle_now - tc->cycle_last) & tc->cc->mask; | |
65 | ||
66 | /* convert to nanoseconds: */ | |
67 | ns_offset = cyclecounter_cyc2ns(tc->cc, cycle_delta); | |
68 | ||
69 | /* update time stamp of timecounter_read_delta() call: */ | |
70 | tc->cycle_last = cycle_now; | |
71 | ||
72 | return ns_offset; | |
73 | } | |
74 | ||
75 | u64 timecounter_read(struct timecounter *tc) | |
76 | { | |
77 | u64 nsec; | |
78 | ||
79 | /* increment time by nanoseconds since last call */ | |
80 | nsec = timecounter_read_delta(tc); | |
81 | nsec += tc->nsec; | |
82 | tc->nsec = nsec; | |
83 | ||
84 | return nsec; | |
85 | } | |
86 | EXPORT_SYMBOL(timecounter_read); | |
87 | ||
88 | u64 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 | * Instead of always treating cycle_tstamp as more recent | |
96 | * than tc->cycle_last, detect when it is too far in the | |
97 | * future and treat it as old time stamp instead. | |
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 | } | |
108 | EXPORT_SYMBOL(timecounter_cyc2time); | |
109 | ||
734efb46 JS |
110 | /*[Clocksource internal variables]--------- |
111 | * curr_clocksource: | |
f1b82746 | 112 | * currently selected clocksource. |
734efb46 JS |
113 | * clocksource_list: |
114 | * linked list with the registered clocksources | |
75c5158f MS |
115 | * clocksource_mutex: |
116 | * protects manipulations to curr_clocksource and the clocksource_list | |
734efb46 JS |
117 | * override_name: |
118 | * Name of the user-specified clocksource. | |
119 | */ | |
f1b82746 | 120 | static struct clocksource *curr_clocksource; |
734efb46 | 121 | static LIST_HEAD(clocksource_list); |
75c5158f | 122 | static DEFINE_MUTEX(clocksource_mutex); |
734efb46 | 123 | static char override_name[32]; |
734efb46 | 124 | |
5d8b34fd TG |
125 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
126 | static LIST_HEAD(watchdog_list); | |
127 | static struct clocksource *watchdog; | |
128 | static struct timer_list watchdog_timer; | |
c55c87c8 | 129 | static struct work_struct watchdog_work; |
5d8b34fd TG |
130 | static DEFINE_SPINLOCK(watchdog_lock); |
131 | static cycle_t watchdog_last; | |
fb63a0eb | 132 | static int watchdog_running; |
b52f52a0 | 133 | |
01548f4d | 134 | static int clocksource_watchdog_kthread(void *data); |
d0981a1b | 135 | static void __clocksource_change_rating(struct clocksource *cs, int rating); |
c55c87c8 | 136 | |
5d8b34fd | 137 | /* |
35c35d1a | 138 | * Interval: 0.5sec Threshold: 0.0625s |
5d8b34fd TG |
139 | */ |
140 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
35c35d1a | 141 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) |
5d8b34fd | 142 | |
01548f4d MS |
143 | static void clocksource_watchdog_work(struct work_struct *work) |
144 | { | |
145 | /* | |
146 | * If kthread_run fails the next watchdog scan over the | |
147 | * watchdog_list will find the unstable clock again. | |
148 | */ | |
149 | kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog"); | |
150 | } | |
151 | ||
8cf4e750 | 152 | static void clocksource_unstable(struct clocksource *cs, int64_t delta) |
5d8b34fd | 153 | { |
5d8b34fd TG |
154 | printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n", |
155 | cs->name, delta); | |
156 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); | |
c55c87c8 MS |
157 | cs->flags |= CLOCK_SOURCE_UNSTABLE; |
158 | schedule_work(&watchdog_work); | |
5d8b34fd TG |
159 | } |
160 | ||
161 | static void clocksource_watchdog(unsigned long data) | |
162 | { | |
c55c87c8 | 163 | struct clocksource *cs; |
5d8b34fd TG |
164 | cycle_t csnow, wdnow; |
165 | int64_t wd_nsec, cs_nsec; | |
c55c87c8 | 166 | int next_cpu; |
5d8b34fd TG |
167 | |
168 | spin_lock(&watchdog_lock); | |
fb63a0eb MS |
169 | if (!watchdog_running) |
170 | goto out; | |
5d8b34fd | 171 | |
8e19608e | 172 | wdnow = watchdog->read(watchdog); |
155ec602 MS |
173 | wd_nsec = clocksource_cyc2ns((wdnow - watchdog_last) & watchdog->mask, |
174 | watchdog->mult, watchdog->shift); | |
5d8b34fd TG |
175 | watchdog_last = wdnow; |
176 | ||
c55c87c8 MS |
177 | list_for_each_entry(cs, &watchdog_list, wd_list) { |
178 | ||
179 | /* Clocksource already marked unstable? */ | |
01548f4d MS |
180 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
181 | schedule_work(&watchdog_work); | |
c55c87c8 | 182 | continue; |
01548f4d | 183 | } |
c55c87c8 | 184 | |
8e19608e | 185 | csnow = cs->read(cs); |
b52f52a0 | 186 | |
8cf4e750 MS |
187 | /* Clocksource initialized ? */ |
188 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG)) { | |
189 | cs->flags |= CLOCK_SOURCE_WATCHDOG; | |
b52f52a0 TG |
190 | cs->wd_last = csnow; |
191 | continue; | |
192 | } | |
193 | ||
8cf4e750 | 194 | /* Check the deviation from the watchdog clocksource. */ |
155ec602 MS |
195 | cs_nsec = clocksource_cyc2ns((csnow - cs->wd_last) & |
196 | cs->mask, cs->mult, cs->shift); | |
8cf4e750 MS |
197 | cs->wd_last = csnow; |
198 | if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) { | |
199 | clocksource_unstable(cs, cs_nsec - wd_nsec); | |
200 | continue; | |
201 | } | |
202 | ||
203 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && | |
204 | (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
205 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
206 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
207 | /* | |
208 | * We just marked the clocksource as highres-capable, | |
209 | * notify the rest of the system as well so that we | |
210 | * transition into high-res mode: | |
211 | */ | |
212 | tick_clock_notify(); | |
5d8b34fd TG |
213 | } |
214 | } | |
215 | ||
c55c87c8 MS |
216 | /* |
217 | * Cycle through CPUs to check if the CPUs stay synchronized | |
218 | * to each other. | |
219 | */ | |
220 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); | |
221 | if (next_cpu >= nr_cpu_ids) | |
222 | next_cpu = cpumask_first(cpu_online_mask); | |
223 | watchdog_timer.expires += WATCHDOG_INTERVAL; | |
224 | add_timer_on(&watchdog_timer, next_cpu); | |
fb63a0eb | 225 | out: |
5d8b34fd TG |
226 | spin_unlock(&watchdog_lock); |
227 | } | |
0f8e8ef7 | 228 | |
fb63a0eb MS |
229 | static inline void clocksource_start_watchdog(void) |
230 | { | |
231 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) | |
232 | return; | |
c55c87c8 | 233 | INIT_WORK(&watchdog_work, clocksource_watchdog_work); |
fb63a0eb MS |
234 | init_timer(&watchdog_timer); |
235 | watchdog_timer.function = clocksource_watchdog; | |
236 | watchdog_last = watchdog->read(watchdog); | |
237 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; | |
238 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); | |
239 | watchdog_running = 1; | |
240 | } | |
241 | ||
242 | static inline void clocksource_stop_watchdog(void) | |
243 | { | |
244 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) | |
245 | return; | |
246 | del_timer(&watchdog_timer); | |
247 | watchdog_running = 0; | |
248 | } | |
249 | ||
0f8e8ef7 MS |
250 | static inline void clocksource_reset_watchdog(void) |
251 | { | |
252 | struct clocksource *cs; | |
253 | ||
254 | list_for_each_entry(cs, &watchdog_list, wd_list) | |
255 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
256 | } | |
257 | ||
b52f52a0 TG |
258 | static void clocksource_resume_watchdog(void) |
259 | { | |
0f8e8ef7 MS |
260 | unsigned long flags; |
261 | ||
262 | spin_lock_irqsave(&watchdog_lock, flags); | |
263 | clocksource_reset_watchdog(); | |
264 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
b52f52a0 TG |
265 | } |
266 | ||
fb63a0eb | 267 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
5d8b34fd | 268 | { |
5d8b34fd TG |
269 | unsigned long flags; |
270 | ||
271 | spin_lock_irqsave(&watchdog_lock, flags); | |
272 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
fb63a0eb | 273 | /* cs is a clocksource to be watched. */ |
5d8b34fd | 274 | list_add(&cs->wd_list, &watchdog_list); |
fb63a0eb | 275 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
948ac6d7 | 276 | } else { |
fb63a0eb | 277 | /* cs is a watchdog. */ |
948ac6d7 | 278 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
5d8b34fd | 279 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
fb63a0eb | 280 | /* Pick the best watchdog. */ |
5d8b34fd | 281 | if (!watchdog || cs->rating > watchdog->rating) { |
5d8b34fd | 282 | watchdog = cs; |
5d8b34fd | 283 | /* Reset watchdog cycles */ |
0f8e8ef7 | 284 | clocksource_reset_watchdog(); |
5d8b34fd TG |
285 | } |
286 | } | |
fb63a0eb MS |
287 | /* Check if the watchdog timer needs to be started. */ |
288 | clocksource_start_watchdog(); | |
5d8b34fd TG |
289 | spin_unlock_irqrestore(&watchdog_lock, flags); |
290 | } | |
fb63a0eb MS |
291 | |
292 | static void clocksource_dequeue_watchdog(struct clocksource *cs) | |
293 | { | |
294 | struct clocksource *tmp; | |
295 | unsigned long flags; | |
296 | ||
297 | spin_lock_irqsave(&watchdog_lock, flags); | |
298 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
299 | /* cs is a watched clocksource. */ | |
300 | list_del_init(&cs->wd_list); | |
301 | } else if (cs == watchdog) { | |
302 | /* Reset watchdog cycles */ | |
303 | clocksource_reset_watchdog(); | |
304 | /* Current watchdog is removed. Find an alternative. */ | |
305 | watchdog = NULL; | |
306 | list_for_each_entry(tmp, &clocksource_list, list) { | |
307 | if (tmp == cs || tmp->flags & CLOCK_SOURCE_MUST_VERIFY) | |
308 | continue; | |
309 | if (!watchdog || tmp->rating > watchdog->rating) | |
310 | watchdog = tmp; | |
311 | } | |
312 | } | |
313 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
314 | /* Check if the watchdog timer needs to be stopped. */ | |
315 | clocksource_stop_watchdog(); | |
316 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
317 | } | |
318 | ||
01548f4d | 319 | static int clocksource_watchdog_kthread(void *data) |
c55c87c8 MS |
320 | { |
321 | struct clocksource *cs, *tmp; | |
322 | unsigned long flags; | |
6ea41d25 | 323 | LIST_HEAD(unstable); |
c55c87c8 | 324 | |
d0981a1b | 325 | mutex_lock(&clocksource_mutex); |
c55c87c8 MS |
326 | spin_lock_irqsave(&watchdog_lock, flags); |
327 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) | |
328 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { | |
329 | list_del_init(&cs->wd_list); | |
6ea41d25 | 330 | list_add(&cs->wd_list, &unstable); |
c55c87c8 MS |
331 | } |
332 | /* Check if the watchdog timer needs to be stopped. */ | |
333 | clocksource_stop_watchdog(); | |
6ea41d25 TG |
334 | spin_unlock_irqrestore(&watchdog_lock, flags); |
335 | ||
336 | /* Needs to be done outside of watchdog lock */ | |
337 | list_for_each_entry_safe(cs, tmp, &unstable, wd_list) { | |
338 | list_del_init(&cs->wd_list); | |
d0981a1b | 339 | __clocksource_change_rating(cs, 0); |
6ea41d25 | 340 | } |
d0981a1b | 341 | mutex_unlock(&clocksource_mutex); |
01548f4d | 342 | return 0; |
c55c87c8 MS |
343 | } |
344 | ||
fb63a0eb MS |
345 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
346 | ||
347 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
5d8b34fd TG |
348 | { |
349 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
350 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
351 | } | |
b52f52a0 | 352 | |
fb63a0eb | 353 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
b52f52a0 | 354 | static inline void clocksource_resume_watchdog(void) { } |
fb63a0eb MS |
355 | |
356 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ | |
5d8b34fd | 357 | |
b52f52a0 TG |
358 | /** |
359 | * clocksource_resume - resume the clocksource(s) | |
360 | */ | |
361 | void clocksource_resume(void) | |
362 | { | |
2e197586 | 363 | struct clocksource *cs; |
b52f52a0 | 364 | |
75c5158f | 365 | mutex_lock(&clocksource_mutex); |
b52f52a0 | 366 | |
75c5158f | 367 | list_for_each_entry(cs, &clocksource_list, list) |
b52f52a0 TG |
368 | if (cs->resume) |
369 | cs->resume(); | |
b52f52a0 TG |
370 | |
371 | clocksource_resume_watchdog(); | |
372 | ||
75c5158f | 373 | mutex_unlock(&clocksource_mutex); |
b52f52a0 TG |
374 | } |
375 | ||
7c3078b6 JW |
376 | /** |
377 | * clocksource_touch_watchdog - Update watchdog | |
378 | * | |
379 | * Update the watchdog after exception contexts such as kgdb so as not | |
380 | * to incorrectly trip the watchdog. | |
381 | * | |
382 | */ | |
383 | void clocksource_touch_watchdog(void) | |
384 | { | |
385 | clocksource_resume_watchdog(); | |
386 | } | |
387 | ||
f1b82746 | 388 | #ifdef CONFIG_GENERIC_TIME |
734efb46 | 389 | |
75c5158f | 390 | static int finished_booting; |
734efb46 JS |
391 | |
392 | /** | |
f1b82746 | 393 | * clocksource_select - Select the best clocksource available |
734efb46 | 394 | * |
75c5158f | 395 | * Private function. Must hold clocksource_mutex when called. |
734efb46 | 396 | * |
92c7e002 TG |
397 | * Select the clocksource with the best rating, or the clocksource, |
398 | * which is selected by userspace override. | |
734efb46 | 399 | */ |
f1b82746 | 400 | static void clocksource_select(void) |
734efb46 | 401 | { |
f1b82746 | 402 | struct clocksource *best, *cs; |
5d8b34fd | 403 | |
75c5158f | 404 | if (!finished_booting || list_empty(&clocksource_list)) |
f1b82746 MS |
405 | return; |
406 | /* First clocksource on the list has the best rating. */ | |
407 | best = list_first_entry(&clocksource_list, struct clocksource, list); | |
408 | /* Check for the override clocksource. */ | |
409 | list_for_each_entry(cs, &clocksource_list, list) { | |
410 | if (strcmp(cs->name, override_name) != 0) | |
411 | continue; | |
412 | /* | |
413 | * Check to make sure we don't switch to a non-highres | |
414 | * capable clocksource if the tick code is in oneshot | |
415 | * mode (highres or nohz) | |
416 | */ | |
417 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && | |
418 | tick_oneshot_mode_active()) { | |
419 | /* Override clocksource cannot be used. */ | |
420 | printk(KERN_WARNING "Override clocksource %s is not " | |
421 | "HRT compatible. Cannot switch while in " | |
422 | "HRT/NOHZ mode\n", cs->name); | |
423 | override_name[0] = 0; | |
424 | } else | |
425 | /* Override clocksource can be used. */ | |
426 | best = cs; | |
427 | break; | |
428 | } | |
75c5158f MS |
429 | if (curr_clocksource != best) { |
430 | printk(KERN_INFO "Switching to clocksource %s\n", best->name); | |
431 | curr_clocksource = best; | |
432 | timekeeping_notify(curr_clocksource); | |
433 | } | |
f1b82746 | 434 | } |
734efb46 | 435 | |
75c5158f MS |
436 | /* |
437 | * clocksource_done_booting - Called near the end of core bootup | |
438 | * | |
439 | * Hack to avoid lots of clocksource churn at boot time. | |
440 | * We use fs_initcall because we want this to start before | |
441 | * device_initcall but after subsys_initcall. | |
442 | */ | |
443 | static int __init clocksource_done_booting(void) | |
444 | { | |
445 | finished_booting = 1; | |
446 | clocksource_select(); | |
447 | return 0; | |
448 | } | |
449 | fs_initcall(clocksource_done_booting); | |
450 | ||
f1b82746 | 451 | #else /* CONFIG_GENERIC_TIME */ |
734efb46 | 452 | |
75c5158f | 453 | static inline void clocksource_select(void) { } |
5d8b34fd | 454 | |
f1b82746 | 455 | #endif |
734efb46 | 456 | |
92c7e002 TG |
457 | /* |
458 | * Enqueue the clocksource sorted by rating | |
734efb46 | 459 | */ |
f1b82746 | 460 | static void clocksource_enqueue(struct clocksource *cs) |
734efb46 | 461 | { |
f1b82746 MS |
462 | struct list_head *entry = &clocksource_list; |
463 | struct clocksource *tmp; | |
92c7e002 | 464 | |
f1b82746 | 465 | list_for_each_entry(tmp, &clocksource_list, list) |
92c7e002 | 466 | /* Keep track of the place, where to insert */ |
f1b82746 MS |
467 | if (tmp->rating >= cs->rating) |
468 | entry = &tmp->list; | |
469 | list_add(&cs->list, entry); | |
734efb46 JS |
470 | } |
471 | ||
472 | /** | |
a2752549 | 473 | * clocksource_register - Used to install new clocksources |
734efb46 JS |
474 | * @t: clocksource to be registered |
475 | * | |
476 | * Returns -EBUSY if registration fails, zero otherwise. | |
477 | */ | |
f1b82746 | 478 | int clocksource_register(struct clocksource *cs) |
734efb46 | 479 | { |
75c5158f | 480 | mutex_lock(&clocksource_mutex); |
f1b82746 MS |
481 | clocksource_enqueue(cs); |
482 | clocksource_select(); | |
fb63a0eb | 483 | clocksource_enqueue_watchdog(cs); |
75c5158f | 484 | mutex_unlock(&clocksource_mutex); |
f1b82746 | 485 | return 0; |
734efb46 | 486 | } |
a2752549 | 487 | EXPORT_SYMBOL(clocksource_register); |
734efb46 | 488 | |
d0981a1b TG |
489 | static void __clocksource_change_rating(struct clocksource *cs, int rating) |
490 | { | |
491 | list_del(&cs->list); | |
492 | cs->rating = rating; | |
493 | clocksource_enqueue(cs); | |
494 | clocksource_select(); | |
495 | } | |
496 | ||
734efb46 | 497 | /** |
92c7e002 | 498 | * clocksource_change_rating - Change the rating of a registered clocksource |
734efb46 | 499 | */ |
92c7e002 | 500 | void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb46 | 501 | { |
75c5158f | 502 | mutex_lock(&clocksource_mutex); |
d0981a1b | 503 | __clocksource_change_rating(cs, rating); |
75c5158f | 504 | mutex_unlock(&clocksource_mutex); |
734efb46 | 505 | } |
fb63a0eb | 506 | EXPORT_SYMBOL(clocksource_change_rating); |
734efb46 | 507 | |
4713e22c TG |
508 | /** |
509 | * clocksource_unregister - remove a registered clocksource | |
510 | */ | |
511 | void clocksource_unregister(struct clocksource *cs) | |
512 | { | |
75c5158f | 513 | mutex_lock(&clocksource_mutex); |
fb63a0eb | 514 | clocksource_dequeue_watchdog(cs); |
4713e22c | 515 | list_del(&cs->list); |
f1b82746 | 516 | clocksource_select(); |
75c5158f | 517 | mutex_unlock(&clocksource_mutex); |
4713e22c | 518 | } |
fb63a0eb | 519 | EXPORT_SYMBOL(clocksource_unregister); |
4713e22c | 520 | |
2b013700 | 521 | #ifdef CONFIG_SYSFS |
734efb46 JS |
522 | /** |
523 | * sysfs_show_current_clocksources - sysfs interface for current clocksource | |
524 | * @dev: unused | |
525 | * @buf: char buffer to be filled with clocksource list | |
526 | * | |
527 | * Provides sysfs interface for listing current clocksource. | |
528 | */ | |
529 | static ssize_t | |
4a0b2b4d AK |
530 | sysfs_show_current_clocksources(struct sys_device *dev, |
531 | struct sysdev_attribute *attr, char *buf) | |
734efb46 | 532 | { |
5e2cb101 | 533 | ssize_t count = 0; |
734efb46 | 534 | |
75c5158f | 535 | mutex_lock(&clocksource_mutex); |
5e2cb101 | 536 | count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); |
75c5158f | 537 | mutex_unlock(&clocksource_mutex); |
734efb46 | 538 | |
5e2cb101 | 539 | return count; |
734efb46 JS |
540 | } |
541 | ||
542 | /** | |
543 | * sysfs_override_clocksource - interface for manually overriding clocksource | |
544 | * @dev: unused | |
545 | * @buf: name of override clocksource | |
546 | * @count: length of buffer | |
547 | * | |
548 | * Takes input from sysfs interface for manually overriding the default | |
549 | * clocksource selction. | |
550 | */ | |
551 | static ssize_t sysfs_override_clocksource(struct sys_device *dev, | |
4a0b2b4d | 552 | struct sysdev_attribute *attr, |
734efb46 JS |
553 | const char *buf, size_t count) |
554 | { | |
555 | size_t ret = count; | |
92c7e002 | 556 | |
734efb46 JS |
557 | /* strings from sysfs write are not 0 terminated! */ |
558 | if (count >= sizeof(override_name)) | |
559 | return -EINVAL; | |
560 | ||
561 | /* strip of \n: */ | |
562 | if (buf[count-1] == '\n') | |
563 | count--; | |
734efb46 | 564 | |
75c5158f | 565 | mutex_lock(&clocksource_mutex); |
734efb46 | 566 | |
92c7e002 TG |
567 | if (count > 0) |
568 | memcpy(override_name, buf, count); | |
734efb46 | 569 | override_name[count] = 0; |
f1b82746 | 570 | clocksource_select(); |
734efb46 | 571 | |
75c5158f | 572 | mutex_unlock(&clocksource_mutex); |
734efb46 JS |
573 | |
574 | return ret; | |
575 | } | |
576 | ||
577 | /** | |
578 | * sysfs_show_available_clocksources - sysfs interface for listing clocksource | |
579 | * @dev: unused | |
580 | * @buf: char buffer to be filled with clocksource list | |
581 | * | |
582 | * Provides sysfs interface for listing registered clocksources | |
583 | */ | |
584 | static ssize_t | |
4a0b2b4d AK |
585 | sysfs_show_available_clocksources(struct sys_device *dev, |
586 | struct sysdev_attribute *attr, | |
587 | char *buf) | |
734efb46 | 588 | { |
2e197586 | 589 | struct clocksource *src; |
5e2cb101 | 590 | ssize_t count = 0; |
734efb46 | 591 | |
75c5158f | 592 | mutex_lock(&clocksource_mutex); |
2e197586 | 593 | list_for_each_entry(src, &clocksource_list, list) { |
cd6d95d8 TG |
594 | /* |
595 | * Don't show non-HRES clocksource if the tick code is | |
596 | * in one shot mode (highres=on or nohz=on) | |
597 | */ | |
598 | if (!tick_oneshot_mode_active() || | |
599 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) | |
3f68535a | 600 | count += snprintf(buf + count, |
5e2cb101 MX |
601 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), |
602 | "%s ", src->name); | |
734efb46 | 603 | } |
75c5158f | 604 | mutex_unlock(&clocksource_mutex); |
734efb46 | 605 | |
5e2cb101 MX |
606 | count += snprintf(buf + count, |
607 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); | |
734efb46 | 608 | |
5e2cb101 | 609 | return count; |
734efb46 JS |
610 | } |
611 | ||
612 | /* | |
613 | * Sysfs setup bits: | |
614 | */ | |
4f95f81a | 615 | static SYSDEV_ATTR(current_clocksource, 0644, sysfs_show_current_clocksources, |
f5f1a24a | 616 | sysfs_override_clocksource); |
734efb46 | 617 | |
4f95f81a | 618 | static SYSDEV_ATTR(available_clocksource, 0444, |
f5f1a24a | 619 | sysfs_show_available_clocksources, NULL); |
734efb46 JS |
620 | |
621 | static struct sysdev_class clocksource_sysclass = { | |
af5ca3f4 | 622 | .name = "clocksource", |
734efb46 JS |
623 | }; |
624 | ||
625 | static struct sys_device device_clocksource = { | |
626 | .id = 0, | |
627 | .cls = &clocksource_sysclass, | |
628 | }; | |
629 | ||
ad596171 | 630 | static int __init init_clocksource_sysfs(void) |
734efb46 JS |
631 | { |
632 | int error = sysdev_class_register(&clocksource_sysclass); | |
633 | ||
634 | if (!error) | |
635 | error = sysdev_register(&device_clocksource); | |
636 | if (!error) | |
637 | error = sysdev_create_file( | |
638 | &device_clocksource, | |
639 | &attr_current_clocksource); | |
640 | if (!error) | |
641 | error = sysdev_create_file( | |
642 | &device_clocksource, | |
643 | &attr_available_clocksource); | |
644 | return error; | |
645 | } | |
646 | ||
647 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 648 | #endif /* CONFIG_SYSFS */ |
734efb46 JS |
649 | |
650 | /** | |
651 | * boot_override_clocksource - boot clock override | |
652 | * @str: override name | |
653 | * | |
654 | * Takes a clocksource= boot argument and uses it | |
655 | * as the clocksource override name. | |
656 | */ | |
657 | static int __init boot_override_clocksource(char* str) | |
658 | { | |
75c5158f | 659 | mutex_lock(&clocksource_mutex); |
734efb46 JS |
660 | if (str) |
661 | strlcpy(override_name, str, sizeof(override_name)); | |
75c5158f | 662 | mutex_unlock(&clocksource_mutex); |
734efb46 JS |
663 | return 1; |
664 | } | |
665 | ||
666 | __setup("clocksource=", boot_override_clocksource); | |
667 | ||
668 | /** | |
669 | * boot_override_clock - Compatibility layer for deprecated boot option | |
670 | * @str: override name | |
671 | * | |
672 | * DEPRECATED! Takes a clock= boot argument and uses it | |
673 | * as the clocksource override name | |
674 | */ | |
675 | static int __init boot_override_clock(char* str) | |
676 | { | |
5d0cf410 JS |
677 | if (!strcmp(str, "pmtmr")) { |
678 | printk("Warning: clock=pmtmr is deprecated. " | |
679 | "Use clocksource=acpi_pm.\n"); | |
680 | return boot_override_clocksource("acpi_pm"); | |
681 | } | |
682 | printk("Warning! clock= boot option is deprecated. " | |
683 | "Use clocksource=xyz\n"); | |
734efb46 JS |
684 | return boot_override_clocksource(str); |
685 | } | |
686 | ||
687 | __setup("clock=", boot_override_clock); |