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