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