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> |
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 | 110 | /*[Clocksource internal variables]--------- |
111 | * curr_clocksource: | |
f1b82746 | 112 | * currently selected clocksource. |
734efb46 | 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 | 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]; |
54a6bc0b | 124 | static int finished_booting; |
734efb46 | 125 | |
5d8b34fd | 126 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
f79e0258 MS |
127 | static void clocksource_watchdog_work(struct work_struct *work); |
128 | ||
5d8b34fd TG |
129 | static LIST_HEAD(watchdog_list); |
130 | static struct clocksource *watchdog; | |
131 | static struct timer_list watchdog_timer; | |
f79e0258 | 132 | static DECLARE_WORK(watchdog_work, clocksource_watchdog_work); |
5d8b34fd TG |
133 | static DEFINE_SPINLOCK(watchdog_lock); |
134 | static cycle_t watchdog_last; | |
fb63a0eb | 135 | static int watchdog_running; |
b52f52a0 | 136 | |
01548f4d | 137 | static int clocksource_watchdog_kthread(void *data); |
d0981a1b | 138 | static void __clocksource_change_rating(struct clocksource *cs, int rating); |
c55c87c8 | 139 | |
5d8b34fd | 140 | /* |
35c35d1a | 141 | * Interval: 0.5sec Threshold: 0.0625s |
5d8b34fd TG |
142 | */ |
143 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
35c35d1a | 144 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) |
5d8b34fd | 145 | |
01548f4d MS |
146 | static void clocksource_watchdog_work(struct work_struct *work) |
147 | { | |
148 | /* | |
149 | * If kthread_run fails the next watchdog scan over the | |
150 | * watchdog_list will find the unstable clock again. | |
151 | */ | |
152 | kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog"); | |
153 | } | |
154 | ||
7285dd7f | 155 | static void __clocksource_unstable(struct clocksource *cs) |
5d8b34fd | 156 | { |
5d8b34fd | 157 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); |
c55c87c8 | 158 | cs->flags |= CLOCK_SOURCE_UNSTABLE; |
54a6bc0b TG |
159 | if (finished_booting) |
160 | schedule_work(&watchdog_work); | |
5d8b34fd TG |
161 | } |
162 | ||
7285dd7f TG |
163 | static void clocksource_unstable(struct clocksource *cs, int64_t delta) |
164 | { | |
165 | printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n", | |
166 | cs->name, delta); | |
167 | __clocksource_unstable(cs); | |
168 | } | |
169 | ||
170 | /** | |
171 | * clocksource_mark_unstable - mark clocksource unstable via watchdog | |
172 | * @cs: clocksource to be marked unstable | |
173 | * | |
174 | * This function is called instead of clocksource_change_rating from | |
175 | * cpu hotplug code to avoid a deadlock between the clocksource mutex | |
176 | * and the cpu hotplug mutex. It defers the update of the clocksource | |
177 | * to the watchdog thread. | |
178 | */ | |
179 | void clocksource_mark_unstable(struct clocksource *cs) | |
180 | { | |
181 | unsigned long flags; | |
182 | ||
183 | spin_lock_irqsave(&watchdog_lock, flags); | |
184 | if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) { | |
185 | if (list_empty(&cs->wd_list)) | |
186 | list_add(&cs->wd_list, &watchdog_list); | |
187 | __clocksource_unstable(cs); | |
188 | } | |
189 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
190 | } | |
191 | ||
5d8b34fd TG |
192 | static void clocksource_watchdog(unsigned long data) |
193 | { | |
c55c87c8 | 194 | struct clocksource *cs; |
5d8b34fd TG |
195 | cycle_t csnow, wdnow; |
196 | int64_t wd_nsec, cs_nsec; | |
c55c87c8 | 197 | int next_cpu; |
5d8b34fd TG |
198 | |
199 | spin_lock(&watchdog_lock); | |
fb63a0eb MS |
200 | if (!watchdog_running) |
201 | goto out; | |
5d8b34fd | 202 | |
8e19608e | 203 | wdnow = watchdog->read(watchdog); |
155ec602 MS |
204 | wd_nsec = clocksource_cyc2ns((wdnow - watchdog_last) & watchdog->mask, |
205 | watchdog->mult, watchdog->shift); | |
5d8b34fd TG |
206 | watchdog_last = wdnow; |
207 | ||
c55c87c8 MS |
208 | list_for_each_entry(cs, &watchdog_list, wd_list) { |
209 | ||
210 | /* Clocksource already marked unstable? */ | |
01548f4d | 211 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
54a6bc0b TG |
212 | if (finished_booting) |
213 | schedule_work(&watchdog_work); | |
c55c87c8 | 214 | continue; |
01548f4d | 215 | } |
c55c87c8 | 216 | |
8e19608e | 217 | csnow = cs->read(cs); |
b52f52a0 | 218 | |
8cf4e750 MS |
219 | /* Clocksource initialized ? */ |
220 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG)) { | |
221 | cs->flags |= CLOCK_SOURCE_WATCHDOG; | |
b52f52a0 TG |
222 | cs->wd_last = csnow; |
223 | continue; | |
224 | } | |
225 | ||
8cf4e750 | 226 | /* Check the deviation from the watchdog clocksource. */ |
155ec602 MS |
227 | cs_nsec = clocksource_cyc2ns((csnow - cs->wd_last) & |
228 | cs->mask, cs->mult, cs->shift); | |
8cf4e750 MS |
229 | cs->wd_last = csnow; |
230 | if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) { | |
231 | clocksource_unstable(cs, cs_nsec - wd_nsec); | |
232 | continue; | |
233 | } | |
234 | ||
235 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && | |
236 | (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
237 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
238 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
239 | /* | |
240 | * We just marked the clocksource as highres-capable, | |
241 | * notify the rest of the system as well so that we | |
242 | * transition into high-res mode: | |
243 | */ | |
244 | tick_clock_notify(); | |
5d8b34fd TG |
245 | } |
246 | } | |
247 | ||
c55c87c8 MS |
248 | /* |
249 | * Cycle through CPUs to check if the CPUs stay synchronized | |
250 | * to each other. | |
251 | */ | |
252 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); | |
253 | if (next_cpu >= nr_cpu_ids) | |
254 | next_cpu = cpumask_first(cpu_online_mask); | |
255 | watchdog_timer.expires += WATCHDOG_INTERVAL; | |
256 | add_timer_on(&watchdog_timer, next_cpu); | |
fb63a0eb | 257 | out: |
5d8b34fd TG |
258 | spin_unlock(&watchdog_lock); |
259 | } | |
0f8e8ef7 | 260 | |
fb63a0eb MS |
261 | static inline void clocksource_start_watchdog(void) |
262 | { | |
263 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) | |
264 | return; | |
265 | init_timer(&watchdog_timer); | |
266 | watchdog_timer.function = clocksource_watchdog; | |
267 | watchdog_last = watchdog->read(watchdog); | |
268 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; | |
269 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); | |
270 | watchdog_running = 1; | |
271 | } | |
272 | ||
273 | static inline void clocksource_stop_watchdog(void) | |
274 | { | |
275 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) | |
276 | return; | |
277 | del_timer(&watchdog_timer); | |
278 | watchdog_running = 0; | |
279 | } | |
280 | ||
0f8e8ef7 MS |
281 | static inline void clocksource_reset_watchdog(void) |
282 | { | |
283 | struct clocksource *cs; | |
284 | ||
285 | list_for_each_entry(cs, &watchdog_list, wd_list) | |
286 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
287 | } | |
288 | ||
b52f52a0 TG |
289 | static void clocksource_resume_watchdog(void) |
290 | { | |
0f8e8ef7 MS |
291 | unsigned long flags; |
292 | ||
293 | spin_lock_irqsave(&watchdog_lock, flags); | |
294 | clocksource_reset_watchdog(); | |
295 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
b52f52a0 TG |
296 | } |
297 | ||
fb63a0eb | 298 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
5d8b34fd | 299 | { |
5d8b34fd TG |
300 | unsigned long flags; |
301 | ||
302 | spin_lock_irqsave(&watchdog_lock, flags); | |
303 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
fb63a0eb | 304 | /* cs is a clocksource to be watched. */ |
5d8b34fd | 305 | list_add(&cs->wd_list, &watchdog_list); |
fb63a0eb | 306 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
948ac6d7 | 307 | } else { |
fb63a0eb | 308 | /* cs is a watchdog. */ |
948ac6d7 | 309 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
5d8b34fd | 310 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
fb63a0eb | 311 | /* Pick the best watchdog. */ |
5d8b34fd | 312 | if (!watchdog || cs->rating > watchdog->rating) { |
5d8b34fd | 313 | watchdog = cs; |
5d8b34fd | 314 | /* Reset watchdog cycles */ |
0f8e8ef7 | 315 | clocksource_reset_watchdog(); |
5d8b34fd TG |
316 | } |
317 | } | |
fb63a0eb MS |
318 | /* Check if the watchdog timer needs to be started. */ |
319 | clocksource_start_watchdog(); | |
5d8b34fd TG |
320 | spin_unlock_irqrestore(&watchdog_lock, flags); |
321 | } | |
fb63a0eb MS |
322 | |
323 | static void clocksource_dequeue_watchdog(struct clocksource *cs) | |
324 | { | |
325 | struct clocksource *tmp; | |
326 | unsigned long flags; | |
327 | ||
328 | spin_lock_irqsave(&watchdog_lock, flags); | |
329 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
330 | /* cs is a watched clocksource. */ | |
331 | list_del_init(&cs->wd_list); | |
332 | } else if (cs == watchdog) { | |
333 | /* Reset watchdog cycles */ | |
334 | clocksource_reset_watchdog(); | |
335 | /* Current watchdog is removed. Find an alternative. */ | |
336 | watchdog = NULL; | |
337 | list_for_each_entry(tmp, &clocksource_list, list) { | |
338 | if (tmp == cs || tmp->flags & CLOCK_SOURCE_MUST_VERIFY) | |
339 | continue; | |
340 | if (!watchdog || tmp->rating > watchdog->rating) | |
341 | watchdog = tmp; | |
342 | } | |
343 | } | |
344 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
345 | /* Check if the watchdog timer needs to be stopped. */ | |
346 | clocksource_stop_watchdog(); | |
347 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
348 | } | |
349 | ||
01548f4d | 350 | static int clocksource_watchdog_kthread(void *data) |
c55c87c8 MS |
351 | { |
352 | struct clocksource *cs, *tmp; | |
353 | unsigned long flags; | |
6ea41d25 | 354 | LIST_HEAD(unstable); |
c55c87c8 | 355 | |
d0981a1b | 356 | mutex_lock(&clocksource_mutex); |
c55c87c8 MS |
357 | spin_lock_irqsave(&watchdog_lock, flags); |
358 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) | |
359 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { | |
360 | list_del_init(&cs->wd_list); | |
6ea41d25 | 361 | list_add(&cs->wd_list, &unstable); |
c55c87c8 MS |
362 | } |
363 | /* Check if the watchdog timer needs to be stopped. */ | |
364 | clocksource_stop_watchdog(); | |
6ea41d25 TG |
365 | spin_unlock_irqrestore(&watchdog_lock, flags); |
366 | ||
367 | /* Needs to be done outside of watchdog lock */ | |
368 | list_for_each_entry_safe(cs, tmp, &unstable, wd_list) { | |
369 | list_del_init(&cs->wd_list); | |
d0981a1b | 370 | __clocksource_change_rating(cs, 0); |
6ea41d25 | 371 | } |
d0981a1b | 372 | mutex_unlock(&clocksource_mutex); |
01548f4d | 373 | return 0; |
c55c87c8 MS |
374 | } |
375 | ||
fb63a0eb MS |
376 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
377 | ||
378 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
5d8b34fd TG |
379 | { |
380 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
381 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
382 | } | |
b52f52a0 | 383 | |
fb63a0eb | 384 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
b52f52a0 | 385 | static inline void clocksource_resume_watchdog(void) { } |
54a6bc0b | 386 | static inline int clocksource_watchdog_kthread(void *data) { return 0; } |
fb63a0eb MS |
387 | |
388 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ | |
5d8b34fd | 389 | |
b52f52a0 TG |
390 | /** |
391 | * clocksource_resume - resume the clocksource(s) | |
392 | */ | |
393 | void clocksource_resume(void) | |
394 | { | |
2e197586 | 395 | struct clocksource *cs; |
b52f52a0 | 396 | |
75c5158f | 397 | list_for_each_entry(cs, &clocksource_list, list) |
b52f52a0 TG |
398 | if (cs->resume) |
399 | cs->resume(); | |
b52f52a0 TG |
400 | |
401 | clocksource_resume_watchdog(); | |
b52f52a0 TG |
402 | } |
403 | ||
7c3078b6 JW |
404 | /** |
405 | * clocksource_touch_watchdog - Update watchdog | |
406 | * | |
407 | * Update the watchdog after exception contexts such as kgdb so as not | |
408 | * to incorrectly trip the watchdog. | |
409 | * | |
410 | */ | |
411 | void clocksource_touch_watchdog(void) | |
412 | { | |
413 | clocksource_resume_watchdog(); | |
414 | } | |
415 | ||
f1b82746 | 416 | #ifdef CONFIG_GENERIC_TIME |
734efb46 | 417 | |
734efb46 | 418 | /** |
f1b82746 | 419 | * clocksource_select - Select the best clocksource available |
734efb46 | 420 | * |
75c5158f | 421 | * Private function. Must hold clocksource_mutex when called. |
734efb46 | 422 | * |
92c7e002 TG |
423 | * Select the clocksource with the best rating, or the clocksource, |
424 | * which is selected by userspace override. | |
734efb46 | 425 | */ |
f1b82746 | 426 | static void clocksource_select(void) |
734efb46 | 427 | { |
f1b82746 | 428 | struct clocksource *best, *cs; |
5d8b34fd | 429 | |
75c5158f | 430 | if (!finished_booting || list_empty(&clocksource_list)) |
f1b82746 MS |
431 | return; |
432 | /* First clocksource on the list has the best rating. */ | |
433 | best = list_first_entry(&clocksource_list, struct clocksource, list); | |
434 | /* Check for the override clocksource. */ | |
435 | list_for_each_entry(cs, &clocksource_list, list) { | |
436 | if (strcmp(cs->name, override_name) != 0) | |
437 | continue; | |
438 | /* | |
439 | * Check to make sure we don't switch to a non-highres | |
440 | * capable clocksource if the tick code is in oneshot | |
441 | * mode (highres or nohz) | |
442 | */ | |
443 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && | |
444 | tick_oneshot_mode_active()) { | |
445 | /* Override clocksource cannot be used. */ | |
446 | printk(KERN_WARNING "Override clocksource %s is not " | |
447 | "HRT compatible. Cannot switch while in " | |
448 | "HRT/NOHZ mode\n", cs->name); | |
449 | override_name[0] = 0; | |
450 | } else | |
451 | /* Override clocksource can be used. */ | |
452 | best = cs; | |
453 | break; | |
454 | } | |
75c5158f MS |
455 | if (curr_clocksource != best) { |
456 | printk(KERN_INFO "Switching to clocksource %s\n", best->name); | |
457 | curr_clocksource = best; | |
458 | timekeeping_notify(curr_clocksource); | |
459 | } | |
f1b82746 | 460 | } |
734efb46 | 461 | |
54a6bc0b TG |
462 | #else /* CONFIG_GENERIC_TIME */ |
463 | ||
464 | static inline void clocksource_select(void) { } | |
465 | ||
466 | #endif | |
467 | ||
75c5158f MS |
468 | /* |
469 | * clocksource_done_booting - Called near the end of core bootup | |
470 | * | |
471 | * Hack to avoid lots of clocksource churn at boot time. | |
472 | * We use fs_initcall because we want this to start before | |
473 | * device_initcall but after subsys_initcall. | |
474 | */ | |
475 | static int __init clocksource_done_booting(void) | |
476 | { | |
477 | finished_booting = 1; | |
54a6bc0b TG |
478 | |
479 | /* | |
480 | * Run the watchdog first to eliminate unstable clock sources | |
481 | */ | |
482 | clocksource_watchdog_kthread(NULL); | |
483 | ||
e6c73305 | 484 | mutex_lock(&clocksource_mutex); |
75c5158f | 485 | clocksource_select(); |
e6c73305 | 486 | mutex_unlock(&clocksource_mutex); |
75c5158f MS |
487 | return 0; |
488 | } | |
489 | fs_initcall(clocksource_done_booting); | |
490 | ||
92c7e002 TG |
491 | /* |
492 | * Enqueue the clocksource sorted by rating | |
734efb46 | 493 | */ |
f1b82746 | 494 | static void clocksource_enqueue(struct clocksource *cs) |
734efb46 | 495 | { |
f1b82746 MS |
496 | struct list_head *entry = &clocksource_list; |
497 | struct clocksource *tmp; | |
92c7e002 | 498 | |
f1b82746 | 499 | list_for_each_entry(tmp, &clocksource_list, list) |
92c7e002 | 500 | /* Keep track of the place, where to insert */ |
f1b82746 MS |
501 | if (tmp->rating >= cs->rating) |
502 | entry = &tmp->list; | |
503 | list_add(&cs->list, entry); | |
734efb46 | 504 | } |
505 | ||
506 | /** | |
a2752549 | 507 | * clocksource_register - Used to install new clocksources |
734efb46 | 508 | * @t: clocksource to be registered |
509 | * | |
510 | * Returns -EBUSY if registration fails, zero otherwise. | |
511 | */ | |
f1b82746 | 512 | int clocksource_register(struct clocksource *cs) |
734efb46 | 513 | { |
75c5158f | 514 | mutex_lock(&clocksource_mutex); |
f1b82746 MS |
515 | clocksource_enqueue(cs); |
516 | clocksource_select(); | |
fb63a0eb | 517 | clocksource_enqueue_watchdog(cs); |
75c5158f | 518 | mutex_unlock(&clocksource_mutex); |
f1b82746 | 519 | return 0; |
734efb46 | 520 | } |
a2752549 | 521 | EXPORT_SYMBOL(clocksource_register); |
734efb46 | 522 | |
d0981a1b TG |
523 | static void __clocksource_change_rating(struct clocksource *cs, int rating) |
524 | { | |
525 | list_del(&cs->list); | |
526 | cs->rating = rating; | |
527 | clocksource_enqueue(cs); | |
528 | clocksource_select(); | |
529 | } | |
530 | ||
734efb46 | 531 | /** |
92c7e002 | 532 | * clocksource_change_rating - Change the rating of a registered clocksource |
734efb46 | 533 | */ |
92c7e002 | 534 | void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb46 | 535 | { |
75c5158f | 536 | mutex_lock(&clocksource_mutex); |
d0981a1b | 537 | __clocksource_change_rating(cs, rating); |
75c5158f | 538 | mutex_unlock(&clocksource_mutex); |
734efb46 | 539 | } |
fb63a0eb | 540 | EXPORT_SYMBOL(clocksource_change_rating); |
734efb46 | 541 | |
4713e22c TG |
542 | /** |
543 | * clocksource_unregister - remove a registered clocksource | |
544 | */ | |
545 | void clocksource_unregister(struct clocksource *cs) | |
546 | { | |
75c5158f | 547 | mutex_lock(&clocksource_mutex); |
fb63a0eb | 548 | clocksource_dequeue_watchdog(cs); |
4713e22c | 549 | list_del(&cs->list); |
f1b82746 | 550 | clocksource_select(); |
75c5158f | 551 | mutex_unlock(&clocksource_mutex); |
4713e22c | 552 | } |
fb63a0eb | 553 | EXPORT_SYMBOL(clocksource_unregister); |
4713e22c | 554 | |
2b013700 | 555 | #ifdef CONFIG_SYSFS |
734efb46 | 556 | /** |
557 | * sysfs_show_current_clocksources - sysfs interface for current clocksource | |
558 | * @dev: unused | |
559 | * @buf: char buffer to be filled with clocksource list | |
560 | * | |
561 | * Provides sysfs interface for listing current clocksource. | |
562 | */ | |
563 | static ssize_t | |
4a0b2b4d AK |
564 | sysfs_show_current_clocksources(struct sys_device *dev, |
565 | struct sysdev_attribute *attr, char *buf) | |
734efb46 | 566 | { |
5e2cb101 | 567 | ssize_t count = 0; |
734efb46 | 568 | |
75c5158f | 569 | mutex_lock(&clocksource_mutex); |
5e2cb101 | 570 | count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); |
75c5158f | 571 | mutex_unlock(&clocksource_mutex); |
734efb46 | 572 | |
5e2cb101 | 573 | return count; |
734efb46 | 574 | } |
575 | ||
576 | /** | |
577 | * sysfs_override_clocksource - interface for manually overriding clocksource | |
578 | * @dev: unused | |
579 | * @buf: name of override clocksource | |
580 | * @count: length of buffer | |
581 | * | |
582 | * Takes input from sysfs interface for manually overriding the default | |
583 | * clocksource selction. | |
584 | */ | |
585 | static ssize_t sysfs_override_clocksource(struct sys_device *dev, | |
4a0b2b4d | 586 | struct sysdev_attribute *attr, |
734efb46 | 587 | const char *buf, size_t count) |
588 | { | |
589 | size_t ret = count; | |
92c7e002 | 590 | |
734efb46 | 591 | /* strings from sysfs write are not 0 terminated! */ |
592 | if (count >= sizeof(override_name)) | |
593 | return -EINVAL; | |
594 | ||
595 | /* strip of \n: */ | |
596 | if (buf[count-1] == '\n') | |
597 | count--; | |
734efb46 | 598 | |
75c5158f | 599 | mutex_lock(&clocksource_mutex); |
734efb46 | 600 | |
92c7e002 TG |
601 | if (count > 0) |
602 | memcpy(override_name, buf, count); | |
734efb46 | 603 | override_name[count] = 0; |
f1b82746 | 604 | clocksource_select(); |
734efb46 | 605 | |
75c5158f | 606 | mutex_unlock(&clocksource_mutex); |
734efb46 | 607 | |
608 | return ret; | |
609 | } | |
610 | ||
611 | /** | |
612 | * sysfs_show_available_clocksources - sysfs interface for listing clocksource | |
613 | * @dev: unused | |
614 | * @buf: char buffer to be filled with clocksource list | |
615 | * | |
616 | * Provides sysfs interface for listing registered clocksources | |
617 | */ | |
618 | static ssize_t | |
4a0b2b4d AK |
619 | sysfs_show_available_clocksources(struct sys_device *dev, |
620 | struct sysdev_attribute *attr, | |
621 | char *buf) | |
734efb46 | 622 | { |
2e197586 | 623 | struct clocksource *src; |
5e2cb101 | 624 | ssize_t count = 0; |
734efb46 | 625 | |
75c5158f | 626 | mutex_lock(&clocksource_mutex); |
2e197586 | 627 | list_for_each_entry(src, &clocksource_list, list) { |
cd6d95d8 TG |
628 | /* |
629 | * Don't show non-HRES clocksource if the tick code is | |
630 | * in one shot mode (highres=on or nohz=on) | |
631 | */ | |
632 | if (!tick_oneshot_mode_active() || | |
633 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) | |
3f68535a | 634 | count += snprintf(buf + count, |
5e2cb101 MX |
635 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), |
636 | "%s ", src->name); | |
734efb46 | 637 | } |
75c5158f | 638 | mutex_unlock(&clocksource_mutex); |
734efb46 | 639 | |
5e2cb101 MX |
640 | count += snprintf(buf + count, |
641 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); | |
734efb46 | 642 | |
5e2cb101 | 643 | return count; |
734efb46 | 644 | } |
645 | ||
646 | /* | |
647 | * Sysfs setup bits: | |
648 | */ | |
4f95f81a | 649 | static SYSDEV_ATTR(current_clocksource, 0644, sysfs_show_current_clocksources, |
f5f1a24a | 650 | sysfs_override_clocksource); |
734efb46 | 651 | |
4f95f81a | 652 | static SYSDEV_ATTR(available_clocksource, 0444, |
f5f1a24a | 653 | sysfs_show_available_clocksources, NULL); |
734efb46 | 654 | |
655 | static struct sysdev_class clocksource_sysclass = { | |
af5ca3f4 | 656 | .name = "clocksource", |
734efb46 | 657 | }; |
658 | ||
659 | static struct sys_device device_clocksource = { | |
660 | .id = 0, | |
661 | .cls = &clocksource_sysclass, | |
662 | }; | |
663 | ||
ad596171 | 664 | static int __init init_clocksource_sysfs(void) |
734efb46 | 665 | { |
666 | int error = sysdev_class_register(&clocksource_sysclass); | |
667 | ||
668 | if (!error) | |
669 | error = sysdev_register(&device_clocksource); | |
670 | if (!error) | |
671 | error = sysdev_create_file( | |
672 | &device_clocksource, | |
673 | &attr_current_clocksource); | |
674 | if (!error) | |
675 | error = sysdev_create_file( | |
676 | &device_clocksource, | |
677 | &attr_available_clocksource); | |
678 | return error; | |
679 | } | |
680 | ||
681 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 682 | #endif /* CONFIG_SYSFS */ |
734efb46 | 683 | |
684 | /** | |
685 | * boot_override_clocksource - boot clock override | |
686 | * @str: override name | |
687 | * | |
688 | * Takes a clocksource= boot argument and uses it | |
689 | * as the clocksource override name. | |
690 | */ | |
691 | static int __init boot_override_clocksource(char* str) | |
692 | { | |
75c5158f | 693 | mutex_lock(&clocksource_mutex); |
734efb46 | 694 | if (str) |
695 | strlcpy(override_name, str, sizeof(override_name)); | |
75c5158f | 696 | mutex_unlock(&clocksource_mutex); |
734efb46 | 697 | return 1; |
698 | } | |
699 | ||
700 | __setup("clocksource=", boot_override_clocksource); | |
701 | ||
702 | /** | |
703 | * boot_override_clock - Compatibility layer for deprecated boot option | |
704 | * @str: override name | |
705 | * | |
706 | * DEPRECATED! Takes a clock= boot argument and uses it | |
707 | * as the clocksource override name | |
708 | */ | |
709 | static int __init boot_override_clock(char* str) | |
710 | { | |
5d0cf410 | 711 | if (!strcmp(str, "pmtmr")) { |
712 | printk("Warning: clock=pmtmr is deprecated. " | |
713 | "Use clocksource=acpi_pm.\n"); | |
714 | return boot_override_clocksource("acpi_pm"); | |
715 | } | |
716 | printk("Warning! clock= boot option is deprecated. " | |
717 | "Use clocksource=xyz\n"); | |
734efb46 | 718 | return boot_override_clocksource(str); |
719 | } | |
720 | ||
721 | __setup("clock=", boot_override_clock); |