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Commit | Line | Data |
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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 | ||
d369a5d8 | 26 | #include <linux/device.h> |
734efb46 | 27 | #include <linux/clocksource.h> |
734efb46 JS |
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 | |
03e13cf5 TG |
34 | #include "tick-internal.h" |
35 | ||
a038a353 PO |
36 | void timecounter_init(struct timecounter *tc, |
37 | const struct cyclecounter *cc, | |
38 | u64 start_tstamp) | |
39 | { | |
40 | tc->cc = cc; | |
41 | tc->cycle_last = cc->read(cc); | |
42 | tc->nsec = start_tstamp; | |
43 | } | |
3586e0a9 | 44 | EXPORT_SYMBOL_GPL(timecounter_init); |
a038a353 PO |
45 | |
46 | /** | |
47 | * timecounter_read_delta - get nanoseconds since last call of this function | |
48 | * @tc: Pointer to time counter | |
49 | * | |
50 | * When the underlying cycle counter runs over, this will be handled | |
51 | * correctly as long as it does not run over more than once between | |
52 | * calls. | |
53 | * | |
54 | * The first call to this function for a new time counter initializes | |
55 | * the time tracking and returns an undefined result. | |
56 | */ | |
57 | static u64 timecounter_read_delta(struct timecounter *tc) | |
58 | { | |
59 | cycle_t cycle_now, cycle_delta; | |
60 | u64 ns_offset; | |
61 | ||
62 | /* read cycle counter: */ | |
63 | cycle_now = tc->cc->read(tc->cc); | |
64 | ||
65 | /* calculate the delta since the last timecounter_read_delta(): */ | |
66 | cycle_delta = (cycle_now - tc->cycle_last) & tc->cc->mask; | |
67 | ||
68 | /* convert to nanoseconds: */ | |
69 | ns_offset = cyclecounter_cyc2ns(tc->cc, cycle_delta); | |
70 | ||
71 | /* update time stamp of timecounter_read_delta() call: */ | |
72 | tc->cycle_last = cycle_now; | |
73 | ||
74 | return ns_offset; | |
75 | } | |
76 | ||
77 | u64 timecounter_read(struct timecounter *tc) | |
78 | { | |
79 | u64 nsec; | |
80 | ||
81 | /* increment time by nanoseconds since last call */ | |
82 | nsec = timecounter_read_delta(tc); | |
83 | nsec += tc->nsec; | |
84 | tc->nsec = nsec; | |
85 | ||
86 | return nsec; | |
87 | } | |
3586e0a9 | 88 | EXPORT_SYMBOL_GPL(timecounter_read); |
a038a353 PO |
89 | |
90 | u64 timecounter_cyc2time(struct timecounter *tc, | |
91 | cycle_t cycle_tstamp) | |
92 | { | |
93 | u64 cycle_delta = (cycle_tstamp - tc->cycle_last) & tc->cc->mask; | |
94 | u64 nsec; | |
95 | ||
96 | /* | |
97 | * Instead of always treating cycle_tstamp as more recent | |
98 | * than tc->cycle_last, detect when it is too far in the | |
99 | * future and treat it as old time stamp instead. | |
100 | */ | |
101 | if (cycle_delta > tc->cc->mask / 2) { | |
102 | cycle_delta = (tc->cycle_last - cycle_tstamp) & tc->cc->mask; | |
103 | nsec = tc->nsec - cyclecounter_cyc2ns(tc->cc, cycle_delta); | |
104 | } else { | |
105 | nsec = cyclecounter_cyc2ns(tc->cc, cycle_delta) + tc->nsec; | |
106 | } | |
107 | ||
108 | return nsec; | |
109 | } | |
3586e0a9 | 110 | EXPORT_SYMBOL_GPL(timecounter_cyc2time); |
a038a353 | 111 | |
7d2f944a TG |
112 | /** |
113 | * clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks | |
114 | * @mult: pointer to mult variable | |
115 | * @shift: pointer to shift variable | |
116 | * @from: frequency to convert from | |
117 | * @to: frequency to convert to | |
5fdade95 | 118 | * @maxsec: guaranteed runtime conversion range in seconds |
7d2f944a TG |
119 | * |
120 | * The function evaluates the shift/mult pair for the scaled math | |
121 | * operations of clocksources and clockevents. | |
122 | * | |
123 | * @to and @from are frequency values in HZ. For clock sources @to is | |
124 | * NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock | |
125 | * event @to is the counter frequency and @from is NSEC_PER_SEC. | |
126 | * | |
5fdade95 | 127 | * The @maxsec conversion range argument controls the time frame in |
7d2f944a TG |
128 | * seconds which must be covered by the runtime conversion with the |
129 | * calculated mult and shift factors. This guarantees that no 64bit | |
130 | * overflow happens when the input value of the conversion is | |
131 | * multiplied with the calculated mult factor. Larger ranges may | |
132 | * reduce the conversion accuracy by chosing smaller mult and shift | |
133 | * factors. | |
134 | */ | |
135 | void | |
5fdade95 | 136 | clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 maxsec) |
7d2f944a TG |
137 | { |
138 | u64 tmp; | |
139 | u32 sft, sftacc= 32; | |
140 | ||
141 | /* | |
142 | * Calculate the shift factor which is limiting the conversion | |
143 | * range: | |
144 | */ | |
5fdade95 | 145 | tmp = ((u64)maxsec * from) >> 32; |
7d2f944a TG |
146 | while (tmp) { |
147 | tmp >>=1; | |
148 | sftacc--; | |
149 | } | |
150 | ||
151 | /* | |
152 | * Find the conversion shift/mult pair which has the best | |
153 | * accuracy and fits the maxsec conversion range: | |
154 | */ | |
155 | for (sft = 32; sft > 0; sft--) { | |
156 | tmp = (u64) to << sft; | |
b5776c4a | 157 | tmp += from / 2; |
7d2f944a TG |
158 | do_div(tmp, from); |
159 | if ((tmp >> sftacc) == 0) | |
160 | break; | |
161 | } | |
162 | *mult = tmp; | |
163 | *shift = sft; | |
164 | } | |
165 | ||
734efb46 JS |
166 | /*[Clocksource internal variables]--------- |
167 | * curr_clocksource: | |
f1b82746 | 168 | * currently selected clocksource. |
734efb46 JS |
169 | * clocksource_list: |
170 | * linked list with the registered clocksources | |
75c5158f MS |
171 | * clocksource_mutex: |
172 | * protects manipulations to curr_clocksource and the clocksource_list | |
734efb46 JS |
173 | * override_name: |
174 | * Name of the user-specified clocksource. | |
175 | */ | |
f1b82746 | 176 | static struct clocksource *curr_clocksource; |
734efb46 | 177 | static LIST_HEAD(clocksource_list); |
75c5158f | 178 | static DEFINE_MUTEX(clocksource_mutex); |
29b54078 | 179 | static char override_name[CS_NAME_LEN]; |
54a6bc0b | 180 | static int finished_booting; |
734efb46 | 181 | |
5d8b34fd | 182 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
f79e0258 | 183 | static void clocksource_watchdog_work(struct work_struct *work); |
332962f2 | 184 | static void clocksource_select(void); |
f79e0258 | 185 | |
5d8b34fd TG |
186 | static LIST_HEAD(watchdog_list); |
187 | static struct clocksource *watchdog; | |
188 | static struct timer_list watchdog_timer; | |
f79e0258 | 189 | static DECLARE_WORK(watchdog_work, clocksource_watchdog_work); |
5d8b34fd | 190 | static DEFINE_SPINLOCK(watchdog_lock); |
fb63a0eb | 191 | static int watchdog_running; |
9fb60336 | 192 | static atomic_t watchdog_reset_pending; |
b52f52a0 | 193 | |
01548f4d | 194 | static int clocksource_watchdog_kthread(void *data); |
d0981a1b | 195 | static void __clocksource_change_rating(struct clocksource *cs, int rating); |
c55c87c8 | 196 | |
5d8b34fd | 197 | /* |
35c35d1a | 198 | * Interval: 0.5sec Threshold: 0.0625s |
5d8b34fd TG |
199 | */ |
200 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
35c35d1a | 201 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) |
5d8b34fd | 202 | |
01548f4d MS |
203 | static void clocksource_watchdog_work(struct work_struct *work) |
204 | { | |
205 | /* | |
206 | * If kthread_run fails the next watchdog scan over the | |
207 | * watchdog_list will find the unstable clock again. | |
208 | */ | |
209 | kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog"); | |
210 | } | |
211 | ||
7285dd7f | 212 | static void __clocksource_unstable(struct clocksource *cs) |
5d8b34fd | 213 | { |
5d8b34fd | 214 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); |
c55c87c8 | 215 | cs->flags |= CLOCK_SOURCE_UNSTABLE; |
54a6bc0b TG |
216 | if (finished_booting) |
217 | schedule_work(&watchdog_work); | |
5d8b34fd TG |
218 | } |
219 | ||
7285dd7f TG |
220 | static void clocksource_unstable(struct clocksource *cs, int64_t delta) |
221 | { | |
222 | printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n", | |
223 | cs->name, delta); | |
224 | __clocksource_unstable(cs); | |
225 | } | |
226 | ||
227 | /** | |
228 | * clocksource_mark_unstable - mark clocksource unstable via watchdog | |
229 | * @cs: clocksource to be marked unstable | |
230 | * | |
231 | * This function is called instead of clocksource_change_rating from | |
232 | * cpu hotplug code to avoid a deadlock between the clocksource mutex | |
233 | * and the cpu hotplug mutex. It defers the update of the clocksource | |
234 | * to the watchdog thread. | |
235 | */ | |
236 | void clocksource_mark_unstable(struct clocksource *cs) | |
237 | { | |
238 | unsigned long flags; | |
239 | ||
240 | spin_lock_irqsave(&watchdog_lock, flags); | |
241 | if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) { | |
242 | if (list_empty(&cs->wd_list)) | |
243 | list_add(&cs->wd_list, &watchdog_list); | |
244 | __clocksource_unstable(cs); | |
245 | } | |
246 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
247 | } | |
248 | ||
5d8b34fd TG |
249 | static void clocksource_watchdog(unsigned long data) |
250 | { | |
c55c87c8 | 251 | struct clocksource *cs; |
5d8b34fd TG |
252 | cycle_t csnow, wdnow; |
253 | int64_t wd_nsec, cs_nsec; | |
9fb60336 | 254 | int next_cpu, reset_pending; |
5d8b34fd TG |
255 | |
256 | spin_lock(&watchdog_lock); | |
fb63a0eb MS |
257 | if (!watchdog_running) |
258 | goto out; | |
5d8b34fd | 259 | |
9fb60336 TG |
260 | reset_pending = atomic_read(&watchdog_reset_pending); |
261 | ||
c55c87c8 MS |
262 | list_for_each_entry(cs, &watchdog_list, wd_list) { |
263 | ||
264 | /* Clocksource already marked unstable? */ | |
01548f4d | 265 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
54a6bc0b TG |
266 | if (finished_booting) |
267 | schedule_work(&watchdog_work); | |
c55c87c8 | 268 | continue; |
01548f4d | 269 | } |
c55c87c8 | 270 | |
b5199515 | 271 | local_irq_disable(); |
8e19608e | 272 | csnow = cs->read(cs); |
b5199515 TG |
273 | wdnow = watchdog->read(watchdog); |
274 | local_irq_enable(); | |
b52f52a0 | 275 | |
8cf4e750 | 276 | /* Clocksource initialized ? */ |
9fb60336 TG |
277 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) || |
278 | atomic_read(&watchdog_reset_pending)) { | |
8cf4e750 | 279 | cs->flags |= CLOCK_SOURCE_WATCHDOG; |
b5199515 TG |
280 | cs->wd_last = wdnow; |
281 | cs->cs_last = csnow; | |
b52f52a0 TG |
282 | continue; |
283 | } | |
284 | ||
b5199515 TG |
285 | wd_nsec = clocksource_cyc2ns((wdnow - cs->wd_last) & watchdog->mask, |
286 | watchdog->mult, watchdog->shift); | |
287 | ||
288 | cs_nsec = clocksource_cyc2ns((csnow - cs->cs_last) & | |
155ec602 | 289 | cs->mask, cs->mult, cs->shift); |
b5199515 TG |
290 | cs->cs_last = csnow; |
291 | cs->wd_last = wdnow; | |
292 | ||
9fb60336 TG |
293 | if (atomic_read(&watchdog_reset_pending)) |
294 | continue; | |
295 | ||
b5199515 | 296 | /* Check the deviation from the watchdog clocksource. */ |
9fb60336 | 297 | if ((abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD)) { |
8cf4e750 MS |
298 | clocksource_unstable(cs, cs_nsec - wd_nsec); |
299 | continue; | |
300 | } | |
301 | ||
302 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && | |
303 | (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
304 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
332962f2 | 305 | /* Mark it valid for high-res. */ |
8cf4e750 | 306 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
332962f2 TG |
307 | |
308 | /* | |
309 | * clocksource_done_booting() will sort it if | |
310 | * finished_booting is not set yet. | |
311 | */ | |
312 | if (!finished_booting) | |
313 | continue; | |
314 | ||
8cf4e750 | 315 | /* |
332962f2 TG |
316 | * If this is not the current clocksource let |
317 | * the watchdog thread reselect it. Due to the | |
318 | * change to high res this clocksource might | |
319 | * be preferred now. If it is the current | |
320 | * clocksource let the tick code know about | |
321 | * that change. | |
8cf4e750 | 322 | */ |
332962f2 TG |
323 | if (cs != curr_clocksource) { |
324 | cs->flags |= CLOCK_SOURCE_RESELECT; | |
325 | schedule_work(&watchdog_work); | |
326 | } else { | |
327 | tick_clock_notify(); | |
328 | } | |
5d8b34fd TG |
329 | } |
330 | } | |
331 | ||
9fb60336 TG |
332 | /* |
333 | * We only clear the watchdog_reset_pending, when we did a | |
334 | * full cycle through all clocksources. | |
335 | */ | |
336 | if (reset_pending) | |
337 | atomic_dec(&watchdog_reset_pending); | |
338 | ||
c55c87c8 MS |
339 | /* |
340 | * Cycle through CPUs to check if the CPUs stay synchronized | |
341 | * to each other. | |
342 | */ | |
343 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); | |
344 | if (next_cpu >= nr_cpu_ids) | |
345 | next_cpu = cpumask_first(cpu_online_mask); | |
346 | watchdog_timer.expires += WATCHDOG_INTERVAL; | |
347 | add_timer_on(&watchdog_timer, next_cpu); | |
fb63a0eb | 348 | out: |
5d8b34fd TG |
349 | spin_unlock(&watchdog_lock); |
350 | } | |
0f8e8ef7 | 351 | |
fb63a0eb MS |
352 | static inline void clocksource_start_watchdog(void) |
353 | { | |
354 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) | |
355 | return; | |
356 | init_timer(&watchdog_timer); | |
357 | watchdog_timer.function = clocksource_watchdog; | |
fb63a0eb MS |
358 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; |
359 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); | |
360 | watchdog_running = 1; | |
361 | } | |
362 | ||
363 | static inline void clocksource_stop_watchdog(void) | |
364 | { | |
365 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) | |
366 | return; | |
367 | del_timer(&watchdog_timer); | |
368 | watchdog_running = 0; | |
369 | } | |
370 | ||
0f8e8ef7 MS |
371 | static inline void clocksource_reset_watchdog(void) |
372 | { | |
373 | struct clocksource *cs; | |
374 | ||
375 | list_for_each_entry(cs, &watchdog_list, wd_list) | |
376 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
377 | } | |
378 | ||
b52f52a0 TG |
379 | static void clocksource_resume_watchdog(void) |
380 | { | |
9fb60336 | 381 | atomic_inc(&watchdog_reset_pending); |
b52f52a0 TG |
382 | } |
383 | ||
fb63a0eb | 384 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
5d8b34fd | 385 | { |
5d8b34fd TG |
386 | unsigned long flags; |
387 | ||
388 | spin_lock_irqsave(&watchdog_lock, flags); | |
389 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
fb63a0eb | 390 | /* cs is a clocksource to be watched. */ |
5d8b34fd | 391 | list_add(&cs->wd_list, &watchdog_list); |
fb63a0eb | 392 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
948ac6d7 | 393 | } else { |
fb63a0eb | 394 | /* cs is a watchdog. */ |
948ac6d7 | 395 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
5d8b34fd | 396 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
fb63a0eb | 397 | /* Pick the best watchdog. */ |
5d8b34fd | 398 | if (!watchdog || cs->rating > watchdog->rating) { |
5d8b34fd | 399 | watchdog = cs; |
5d8b34fd | 400 | /* Reset watchdog cycles */ |
0f8e8ef7 | 401 | clocksource_reset_watchdog(); |
5d8b34fd TG |
402 | } |
403 | } | |
fb63a0eb MS |
404 | /* Check if the watchdog timer needs to be started. */ |
405 | clocksource_start_watchdog(); | |
5d8b34fd TG |
406 | spin_unlock_irqrestore(&watchdog_lock, flags); |
407 | } | |
fb63a0eb MS |
408 | |
409 | static void clocksource_dequeue_watchdog(struct clocksource *cs) | |
410 | { | |
fb63a0eb MS |
411 | unsigned long flags; |
412 | ||
413 | spin_lock_irqsave(&watchdog_lock, flags); | |
a89c7edb TG |
414 | if (cs != watchdog) { |
415 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
416 | /* cs is a watched clocksource. */ | |
417 | list_del_init(&cs->wd_list); | |
418 | /* Check if the watchdog timer needs to be stopped. */ | |
419 | clocksource_stop_watchdog(); | |
fb63a0eb MS |
420 | } |
421 | } | |
fb63a0eb MS |
422 | spin_unlock_irqrestore(&watchdog_lock, flags); |
423 | } | |
424 | ||
332962f2 | 425 | static int __clocksource_watchdog_kthread(void) |
c55c87c8 MS |
426 | { |
427 | struct clocksource *cs, *tmp; | |
428 | unsigned long flags; | |
6ea41d25 | 429 | LIST_HEAD(unstable); |
332962f2 | 430 | int select = 0; |
c55c87c8 MS |
431 | |
432 | spin_lock_irqsave(&watchdog_lock, flags); | |
332962f2 | 433 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { |
c55c87c8 MS |
434 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
435 | list_del_init(&cs->wd_list); | |
6ea41d25 | 436 | list_add(&cs->wd_list, &unstable); |
332962f2 TG |
437 | select = 1; |
438 | } | |
439 | if (cs->flags & CLOCK_SOURCE_RESELECT) { | |
440 | cs->flags &= ~CLOCK_SOURCE_RESELECT; | |
441 | select = 1; | |
c55c87c8 | 442 | } |
332962f2 | 443 | } |
c55c87c8 MS |
444 | /* Check if the watchdog timer needs to be stopped. */ |
445 | clocksource_stop_watchdog(); | |
6ea41d25 TG |
446 | spin_unlock_irqrestore(&watchdog_lock, flags); |
447 | ||
448 | /* Needs to be done outside of watchdog lock */ | |
449 | list_for_each_entry_safe(cs, tmp, &unstable, wd_list) { | |
450 | list_del_init(&cs->wd_list); | |
d0981a1b | 451 | __clocksource_change_rating(cs, 0); |
6ea41d25 | 452 | } |
332962f2 TG |
453 | return select; |
454 | } | |
455 | ||
456 | static int clocksource_watchdog_kthread(void *data) | |
457 | { | |
458 | mutex_lock(&clocksource_mutex); | |
459 | if (__clocksource_watchdog_kthread()) | |
460 | clocksource_select(); | |
d0981a1b | 461 | mutex_unlock(&clocksource_mutex); |
01548f4d | 462 | return 0; |
c55c87c8 MS |
463 | } |
464 | ||
7eaeb343 TG |
465 | static bool clocksource_is_watchdog(struct clocksource *cs) |
466 | { | |
467 | return cs == watchdog; | |
468 | } | |
469 | ||
fb63a0eb MS |
470 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
471 | ||
472 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
5d8b34fd TG |
473 | { |
474 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
475 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
476 | } | |
b52f52a0 | 477 | |
fb63a0eb | 478 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
b52f52a0 | 479 | static inline void clocksource_resume_watchdog(void) { } |
332962f2 | 480 | static inline int __clocksource_watchdog_kthread(void) { return 0; } |
7eaeb343 | 481 | static bool clocksource_is_watchdog(struct clocksource *cs) { return false; } |
397bbf6d | 482 | void clocksource_mark_unstable(struct clocksource *cs) { } |
fb63a0eb MS |
483 | |
484 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ | |
5d8b34fd | 485 | |
c54a42b1 MD |
486 | /** |
487 | * clocksource_suspend - suspend the clocksource(s) | |
488 | */ | |
489 | void clocksource_suspend(void) | |
490 | { | |
491 | struct clocksource *cs; | |
492 | ||
493 | list_for_each_entry_reverse(cs, &clocksource_list, list) | |
494 | if (cs->suspend) | |
495 | cs->suspend(cs); | |
496 | } | |
497 | ||
b52f52a0 TG |
498 | /** |
499 | * clocksource_resume - resume the clocksource(s) | |
500 | */ | |
501 | void clocksource_resume(void) | |
502 | { | |
2e197586 | 503 | struct clocksource *cs; |
b52f52a0 | 504 | |
75c5158f | 505 | list_for_each_entry(cs, &clocksource_list, list) |
b52f52a0 | 506 | if (cs->resume) |
17622339 | 507 | cs->resume(cs); |
b52f52a0 TG |
508 | |
509 | clocksource_resume_watchdog(); | |
b52f52a0 TG |
510 | } |
511 | ||
7c3078b6 JW |
512 | /** |
513 | * clocksource_touch_watchdog - Update watchdog | |
514 | * | |
515 | * Update the watchdog after exception contexts such as kgdb so as not | |
7b7422a5 TG |
516 | * to incorrectly trip the watchdog. This might fail when the kernel |
517 | * was stopped in code which holds watchdog_lock. | |
7c3078b6 JW |
518 | */ |
519 | void clocksource_touch_watchdog(void) | |
520 | { | |
521 | clocksource_resume_watchdog(); | |
522 | } | |
523 | ||
d65670a7 JS |
524 | /** |
525 | * clocksource_max_adjustment- Returns max adjustment amount | |
526 | * @cs: Pointer to clocksource | |
527 | * | |
528 | */ | |
529 | static u32 clocksource_max_adjustment(struct clocksource *cs) | |
530 | { | |
531 | u64 ret; | |
532 | /* | |
88b28adf | 533 | * We won't try to correct for more than 11% adjustments (110,000 ppm), |
d65670a7 JS |
534 | */ |
535 | ret = (u64)cs->mult * 11; | |
536 | do_div(ret,100); | |
537 | return (u32)ret; | |
538 | } | |
539 | ||
98962465 | 540 | /** |
87d8b9eb SB |
541 | * clocks_calc_max_nsecs - Returns maximum nanoseconds that can be converted |
542 | * @mult: cycle to nanosecond multiplier | |
543 | * @shift: cycle to nanosecond divisor (power of two) | |
544 | * @maxadj: maximum adjustment value to mult (~11%) | |
545 | * @mask: bitmask for two's complement subtraction of non 64 bit counters | |
98962465 | 546 | */ |
87d8b9eb | 547 | u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask) |
98962465 JH |
548 | { |
549 | u64 max_nsecs, max_cycles; | |
550 | ||
551 | /* | |
552 | * Calculate the maximum number of cycles that we can pass to the | |
553 | * cyc2ns function without overflowing a 64-bit signed result. The | |
87d8b9eb | 554 | * maximum number of cycles is equal to ULLONG_MAX/(mult+maxadj) |
d65670a7 | 555 | * which is equivalent to the below. |
87d8b9eb SB |
556 | * max_cycles < (2^63)/(mult + maxadj) |
557 | * max_cycles < 2^(log2((2^63)/(mult + maxadj))) | |
558 | * max_cycles < 2^(log2(2^63) - log2(mult + maxadj)) | |
559 | * max_cycles < 2^(63 - log2(mult + maxadj)) | |
560 | * max_cycles < 1 << (63 - log2(mult + maxadj)) | |
98962465 JH |
561 | * Please note that we add 1 to the result of the log2 to account for |
562 | * any rounding errors, ensure the above inequality is satisfied and | |
563 | * no overflow will occur. | |
564 | */ | |
87d8b9eb | 565 | max_cycles = 1ULL << (63 - (ilog2(mult + maxadj) + 1)); |
98962465 JH |
566 | |
567 | /* | |
568 | * The actual maximum number of cycles we can defer the clocksource is | |
87d8b9eb | 569 | * determined by the minimum of max_cycles and mask. |
d65670a7 JS |
570 | * Note: Here we subtract the maxadj to make sure we don't sleep for |
571 | * too long if there's a large negative adjustment. | |
98962465 | 572 | */ |
87d8b9eb SB |
573 | max_cycles = min(max_cycles, mask); |
574 | max_nsecs = clocksource_cyc2ns(max_cycles, mult - maxadj, shift); | |
575 | ||
576 | return max_nsecs; | |
577 | } | |
578 | ||
579 | /** | |
580 | * clocksource_max_deferment - Returns max time the clocksource can be deferred | |
581 | * @cs: Pointer to clocksource | |
582 | * | |
583 | */ | |
584 | static u64 clocksource_max_deferment(struct clocksource *cs) | |
585 | { | |
586 | u64 max_nsecs; | |
98962465 | 587 | |
87d8b9eb SB |
588 | max_nsecs = clocks_calc_max_nsecs(cs->mult, cs->shift, cs->maxadj, |
589 | cs->mask); | |
98962465 JH |
590 | /* |
591 | * To ensure that the clocksource does not wrap whilst we are idle, | |
592 | * limit the time the clocksource can be deferred by 12.5%. Please | |
593 | * note a margin of 12.5% is used because this can be computed with | |
594 | * a shift, versus say 10% which would require division. | |
595 | */ | |
b1f91966 | 596 | return max_nsecs - (max_nsecs >> 3); |
98962465 JH |
597 | } |
598 | ||
592913ec | 599 | #ifndef CONFIG_ARCH_USES_GETTIMEOFFSET |
734efb46 | 600 | |
f5a2e343 | 601 | static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur) |
5d33b883 TG |
602 | { |
603 | struct clocksource *cs; | |
604 | ||
605 | if (!finished_booting || list_empty(&clocksource_list)) | |
606 | return NULL; | |
607 | ||
608 | /* | |
609 | * We pick the clocksource with the highest rating. If oneshot | |
610 | * mode is active, we pick the highres valid clocksource with | |
611 | * the best rating. | |
612 | */ | |
613 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
614 | if (skipcur && cs == curr_clocksource) |
615 | continue; | |
5d33b883 TG |
616 | if (oneshot && !(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES)) |
617 | continue; | |
618 | return cs; | |
619 | } | |
620 | return NULL; | |
621 | } | |
622 | ||
f5a2e343 | 623 | static void __clocksource_select(bool skipcur) |
734efb46 | 624 | { |
5d33b883 | 625 | bool oneshot = tick_oneshot_mode_active(); |
f1b82746 | 626 | struct clocksource *best, *cs; |
5d8b34fd | 627 | |
5d33b883 | 628 | /* Find the best suitable clocksource */ |
f5a2e343 | 629 | best = clocksource_find_best(oneshot, skipcur); |
5d33b883 | 630 | if (!best) |
f1b82746 | 631 | return; |
5d33b883 | 632 | |
f1b82746 MS |
633 | /* Check for the override clocksource. */ |
634 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
635 | if (skipcur && cs == curr_clocksource) |
636 | continue; | |
f1b82746 MS |
637 | if (strcmp(cs->name, override_name) != 0) |
638 | continue; | |
639 | /* | |
640 | * Check to make sure we don't switch to a non-highres | |
641 | * capable clocksource if the tick code is in oneshot | |
642 | * mode (highres or nohz) | |
643 | */ | |
5d33b883 | 644 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && oneshot) { |
f1b82746 MS |
645 | /* Override clocksource cannot be used. */ |
646 | printk(KERN_WARNING "Override clocksource %s is not " | |
647 | "HRT compatible. Cannot switch while in " | |
648 | "HRT/NOHZ mode\n", cs->name); | |
649 | override_name[0] = 0; | |
650 | } else | |
651 | /* Override clocksource can be used. */ | |
652 | best = cs; | |
653 | break; | |
654 | } | |
ba919d1c TG |
655 | |
656 | if (curr_clocksource != best && !timekeeping_notify(best)) { | |
657 | pr_info("Switched to clocksource %s\n", best->name); | |
75c5158f | 658 | curr_clocksource = best; |
75c5158f | 659 | } |
f1b82746 | 660 | } |
734efb46 | 661 | |
f5a2e343 TG |
662 | /** |
663 | * clocksource_select - Select the best clocksource available | |
664 | * | |
665 | * Private function. Must hold clocksource_mutex when called. | |
666 | * | |
667 | * Select the clocksource with the best rating, or the clocksource, | |
668 | * which is selected by userspace override. | |
669 | */ | |
670 | static void clocksource_select(void) | |
671 | { | |
672 | return __clocksource_select(false); | |
673 | } | |
674 | ||
7eaeb343 TG |
675 | static void clocksource_select_fallback(void) |
676 | { | |
677 | return __clocksource_select(true); | |
678 | } | |
679 | ||
592913ec | 680 | #else /* !CONFIG_ARCH_USES_GETTIMEOFFSET */ |
54a6bc0b TG |
681 | |
682 | static inline void clocksource_select(void) { } | |
1eaff672 | 683 | static inline void clocksource_select_fallback(void) { } |
54a6bc0b TG |
684 | |
685 | #endif | |
686 | ||
75c5158f MS |
687 | /* |
688 | * clocksource_done_booting - Called near the end of core bootup | |
689 | * | |
690 | * Hack to avoid lots of clocksource churn at boot time. | |
691 | * We use fs_initcall because we want this to start before | |
692 | * device_initcall but after subsys_initcall. | |
693 | */ | |
694 | static int __init clocksource_done_booting(void) | |
695 | { | |
ad6759fb JS |
696 | mutex_lock(&clocksource_mutex); |
697 | curr_clocksource = clocksource_default_clock(); | |
75c5158f | 698 | finished_booting = 1; |
54a6bc0b TG |
699 | /* |
700 | * Run the watchdog first to eliminate unstable clock sources | |
701 | */ | |
332962f2 | 702 | __clocksource_watchdog_kthread(); |
75c5158f | 703 | clocksource_select(); |
e6c73305 | 704 | mutex_unlock(&clocksource_mutex); |
75c5158f MS |
705 | return 0; |
706 | } | |
707 | fs_initcall(clocksource_done_booting); | |
708 | ||
92c7e002 TG |
709 | /* |
710 | * Enqueue the clocksource sorted by rating | |
734efb46 | 711 | */ |
f1b82746 | 712 | static void clocksource_enqueue(struct clocksource *cs) |
734efb46 | 713 | { |
f1b82746 MS |
714 | struct list_head *entry = &clocksource_list; |
715 | struct clocksource *tmp; | |
92c7e002 | 716 | |
f1b82746 | 717 | list_for_each_entry(tmp, &clocksource_list, list) |
92c7e002 | 718 | /* Keep track of the place, where to insert */ |
f1b82746 MS |
719 | if (tmp->rating >= cs->rating) |
720 | entry = &tmp->list; | |
721 | list_add(&cs->list, entry); | |
734efb46 JS |
722 | } |
723 | ||
d7e81c26 | 724 | /** |
852db46d | 725 | * __clocksource_updatefreq_scale - Used update clocksource with new freq |
b1b73d09 | 726 | * @cs: clocksource to be registered |
d7e81c26 JS |
727 | * @scale: Scale factor multiplied against freq to get clocksource hz |
728 | * @freq: clocksource frequency (cycles per second) divided by scale | |
729 | * | |
852db46d | 730 | * This should only be called from the clocksource->enable() method. |
d7e81c26 JS |
731 | * |
732 | * This *SHOULD NOT* be called directly! Please use the | |
852db46d | 733 | * clocksource_updatefreq_hz() or clocksource_updatefreq_khz helper functions. |
d7e81c26 | 734 | */ |
852db46d | 735 | void __clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq) |
d7e81c26 | 736 | { |
c0e299b1 | 737 | u64 sec; |
d7e81c26 | 738 | /* |
724ed53e TG |
739 | * Calc the maximum number of seconds which we can run before |
740 | * wrapping around. For clocksources which have a mask > 32bit | |
741 | * we need to limit the max sleep time to have a good | |
742 | * conversion precision. 10 minutes is still a reasonable | |
743 | * amount. That results in a shift value of 24 for a | |
744 | * clocksource with mask >= 40bit and f >= 4GHz. That maps to | |
745 | * ~ 0.06ppm granularity for NTP. We apply the same 12.5% | |
746 | * margin as we do in clocksource_max_deferment() | |
d7e81c26 | 747 | */ |
b1f91966 | 748 | sec = (cs->mask - (cs->mask >> 3)); |
724ed53e TG |
749 | do_div(sec, freq); |
750 | do_div(sec, scale); | |
751 | if (!sec) | |
752 | sec = 1; | |
753 | else if (sec > 600 && cs->mask > UINT_MAX) | |
754 | sec = 600; | |
755 | ||
d7e81c26 | 756 | clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, |
724ed53e | 757 | NSEC_PER_SEC / scale, sec * scale); |
d65670a7 JS |
758 | |
759 | /* | |
760 | * for clocksources that have large mults, to avoid overflow. | |
761 | * Since mult may be adjusted by ntp, add an safety extra margin | |
762 | * | |
763 | */ | |
764 | cs->maxadj = clocksource_max_adjustment(cs); | |
765 | while ((cs->mult + cs->maxadj < cs->mult) | |
766 | || (cs->mult - cs->maxadj > cs->mult)) { | |
767 | cs->mult >>= 1; | |
768 | cs->shift--; | |
769 | cs->maxadj = clocksource_max_adjustment(cs); | |
770 | } | |
771 | ||
d7e81c26 | 772 | cs->max_idle_ns = clocksource_max_deferment(cs); |
852db46d JS |
773 | } |
774 | EXPORT_SYMBOL_GPL(__clocksource_updatefreq_scale); | |
775 | ||
776 | /** | |
777 | * __clocksource_register_scale - Used to install new clocksources | |
b1b73d09 | 778 | * @cs: clocksource to be registered |
852db46d JS |
779 | * @scale: Scale factor multiplied against freq to get clocksource hz |
780 | * @freq: clocksource frequency (cycles per second) divided by scale | |
781 | * | |
782 | * Returns -EBUSY if registration fails, zero otherwise. | |
783 | * | |
784 | * This *SHOULD NOT* be called directly! Please use the | |
785 | * clocksource_register_hz() or clocksource_register_khz helper functions. | |
786 | */ | |
787 | int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) | |
788 | { | |
789 | ||
b595076a | 790 | /* Initialize mult/shift and max_idle_ns */ |
852db46d | 791 | __clocksource_updatefreq_scale(cs, scale, freq); |
d7e81c26 | 792 | |
852db46d | 793 | /* Add clocksource to the clcoksource list */ |
d7e81c26 JS |
794 | mutex_lock(&clocksource_mutex); |
795 | clocksource_enqueue(cs); | |
d7e81c26 | 796 | clocksource_enqueue_watchdog(cs); |
e05b2efb | 797 | clocksource_select(); |
d7e81c26 JS |
798 | mutex_unlock(&clocksource_mutex); |
799 | return 0; | |
800 | } | |
801 | EXPORT_SYMBOL_GPL(__clocksource_register_scale); | |
802 | ||
803 | ||
734efb46 | 804 | /** |
a2752549 | 805 | * clocksource_register - Used to install new clocksources |
b1b73d09 | 806 | * @cs: clocksource to be registered |
734efb46 JS |
807 | * |
808 | * Returns -EBUSY if registration fails, zero otherwise. | |
809 | */ | |
f1b82746 | 810 | int clocksource_register(struct clocksource *cs) |
734efb46 | 811 | { |
d65670a7 JS |
812 | /* calculate max adjustment for given mult/shift */ |
813 | cs->maxadj = clocksource_max_adjustment(cs); | |
814 | WARN_ONCE(cs->mult + cs->maxadj < cs->mult, | |
815 | "Clocksource %s might overflow on 11%% adjustment\n", | |
816 | cs->name); | |
817 | ||
98962465 JH |
818 | /* calculate max idle time permitted for this clocksource */ |
819 | cs->max_idle_ns = clocksource_max_deferment(cs); | |
820 | ||
75c5158f | 821 | mutex_lock(&clocksource_mutex); |
f1b82746 | 822 | clocksource_enqueue(cs); |
fb63a0eb | 823 | clocksource_enqueue_watchdog(cs); |
e05b2efb | 824 | clocksource_select(); |
75c5158f | 825 | mutex_unlock(&clocksource_mutex); |
f1b82746 | 826 | return 0; |
734efb46 | 827 | } |
a2752549 | 828 | EXPORT_SYMBOL(clocksource_register); |
734efb46 | 829 | |
d0981a1b TG |
830 | static void __clocksource_change_rating(struct clocksource *cs, int rating) |
831 | { | |
832 | list_del(&cs->list); | |
833 | cs->rating = rating; | |
834 | clocksource_enqueue(cs); | |
d0981a1b TG |
835 | } |
836 | ||
734efb46 | 837 | /** |
92c7e002 | 838 | * clocksource_change_rating - Change the rating of a registered clocksource |
b1b73d09 KK |
839 | * @cs: clocksource to be changed |
840 | * @rating: new rating | |
734efb46 | 841 | */ |
92c7e002 | 842 | void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb46 | 843 | { |
75c5158f | 844 | mutex_lock(&clocksource_mutex); |
d0981a1b | 845 | __clocksource_change_rating(cs, rating); |
332962f2 | 846 | clocksource_select(); |
75c5158f | 847 | mutex_unlock(&clocksource_mutex); |
734efb46 | 848 | } |
fb63a0eb | 849 | EXPORT_SYMBOL(clocksource_change_rating); |
734efb46 | 850 | |
7eaeb343 TG |
851 | /* |
852 | * Unbind clocksource @cs. Called with clocksource_mutex held | |
853 | */ | |
854 | static int clocksource_unbind(struct clocksource *cs) | |
855 | { | |
856 | /* | |
857 | * I really can't convince myself to support this on hardware | |
858 | * designed by lobotomized monkeys. | |
859 | */ | |
860 | if (clocksource_is_watchdog(cs)) | |
861 | return -EBUSY; | |
862 | ||
863 | if (cs == curr_clocksource) { | |
864 | /* Select and try to install a replacement clock source */ | |
865 | clocksource_select_fallback(); | |
866 | if (curr_clocksource == cs) | |
867 | return -EBUSY; | |
868 | } | |
869 | clocksource_dequeue_watchdog(cs); | |
870 | list_del_init(&cs->list); | |
871 | return 0; | |
872 | } | |
873 | ||
4713e22c TG |
874 | /** |
875 | * clocksource_unregister - remove a registered clocksource | |
b1b73d09 | 876 | * @cs: clocksource to be unregistered |
4713e22c | 877 | */ |
a89c7edb | 878 | int clocksource_unregister(struct clocksource *cs) |
4713e22c | 879 | { |
a89c7edb TG |
880 | int ret = 0; |
881 | ||
75c5158f | 882 | mutex_lock(&clocksource_mutex); |
a89c7edb TG |
883 | if (!list_empty(&cs->list)) |
884 | ret = clocksource_unbind(cs); | |
75c5158f | 885 | mutex_unlock(&clocksource_mutex); |
a89c7edb | 886 | return ret; |
4713e22c | 887 | } |
fb63a0eb | 888 | EXPORT_SYMBOL(clocksource_unregister); |
4713e22c | 889 | |
2b013700 | 890 | #ifdef CONFIG_SYSFS |
734efb46 JS |
891 | /** |
892 | * sysfs_show_current_clocksources - sysfs interface for current clocksource | |
893 | * @dev: unused | |
b1b73d09 | 894 | * @attr: unused |
734efb46 JS |
895 | * @buf: char buffer to be filled with clocksource list |
896 | * | |
897 | * Provides sysfs interface for listing current clocksource. | |
898 | */ | |
899 | static ssize_t | |
d369a5d8 KS |
900 | sysfs_show_current_clocksources(struct device *dev, |
901 | struct device_attribute *attr, char *buf) | |
734efb46 | 902 | { |
5e2cb101 | 903 | ssize_t count = 0; |
734efb46 | 904 | |
75c5158f | 905 | mutex_lock(&clocksource_mutex); |
5e2cb101 | 906 | count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); |
75c5158f | 907 | mutex_unlock(&clocksource_mutex); |
734efb46 | 908 | |
5e2cb101 | 909 | return count; |
734efb46 JS |
910 | } |
911 | ||
891292a7 | 912 | ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt) |
29b54078 TG |
913 | { |
914 | size_t ret = cnt; | |
915 | ||
916 | /* strings from sysfs write are not 0 terminated! */ | |
917 | if (!cnt || cnt >= CS_NAME_LEN) | |
918 | return -EINVAL; | |
919 | ||
920 | /* strip of \n: */ | |
921 | if (buf[cnt-1] == '\n') | |
922 | cnt--; | |
923 | if (cnt > 0) | |
924 | memcpy(dst, buf, cnt); | |
925 | dst[cnt] = 0; | |
926 | return ret; | |
927 | } | |
928 | ||
734efb46 JS |
929 | /** |
930 | * sysfs_override_clocksource - interface for manually overriding clocksource | |
931 | * @dev: unused | |
b1b73d09 | 932 | * @attr: unused |
734efb46 JS |
933 | * @buf: name of override clocksource |
934 | * @count: length of buffer | |
935 | * | |
936 | * Takes input from sysfs interface for manually overriding the default | |
b71a8eb0 | 937 | * clocksource selection. |
734efb46 | 938 | */ |
d369a5d8 KS |
939 | static ssize_t sysfs_override_clocksource(struct device *dev, |
940 | struct device_attribute *attr, | |
734efb46 JS |
941 | const char *buf, size_t count) |
942 | { | |
233bcb41 | 943 | ssize_t ret; |
734efb46 | 944 | |
75c5158f | 945 | mutex_lock(&clocksource_mutex); |
734efb46 | 946 | |
03e13cf5 | 947 | ret = sysfs_get_uname(buf, override_name, count); |
29b54078 TG |
948 | if (ret >= 0) |
949 | clocksource_select(); | |
734efb46 | 950 | |
75c5158f | 951 | mutex_unlock(&clocksource_mutex); |
734efb46 JS |
952 | |
953 | return ret; | |
954 | } | |
955 | ||
7eaeb343 TG |
956 | /** |
957 | * sysfs_unbind_current_clocksource - interface for manually unbinding clocksource | |
958 | * @dev: unused | |
959 | * @attr: unused | |
960 | * @buf: unused | |
961 | * @count: length of buffer | |
962 | * | |
963 | * Takes input from sysfs interface for manually unbinding a clocksource. | |
964 | */ | |
965 | static ssize_t sysfs_unbind_clocksource(struct device *dev, | |
966 | struct device_attribute *attr, | |
967 | const char *buf, size_t count) | |
968 | { | |
969 | struct clocksource *cs; | |
970 | char name[CS_NAME_LEN]; | |
233bcb41 | 971 | ssize_t ret; |
7eaeb343 | 972 | |
03e13cf5 | 973 | ret = sysfs_get_uname(buf, name, count); |
7eaeb343 TG |
974 | if (ret < 0) |
975 | return ret; | |
976 | ||
977 | ret = -ENODEV; | |
978 | mutex_lock(&clocksource_mutex); | |
979 | list_for_each_entry(cs, &clocksource_list, list) { | |
980 | if (strcmp(cs->name, name)) | |
981 | continue; | |
982 | ret = clocksource_unbind(cs); | |
983 | break; | |
984 | } | |
985 | mutex_unlock(&clocksource_mutex); | |
986 | ||
987 | return ret ? ret : count; | |
988 | } | |
989 | ||
734efb46 JS |
990 | /** |
991 | * sysfs_show_available_clocksources - sysfs interface for listing clocksource | |
992 | * @dev: unused | |
b1b73d09 | 993 | * @attr: unused |
734efb46 JS |
994 | * @buf: char buffer to be filled with clocksource list |
995 | * | |
996 | * Provides sysfs interface for listing registered clocksources | |
997 | */ | |
998 | static ssize_t | |
d369a5d8 KS |
999 | sysfs_show_available_clocksources(struct device *dev, |
1000 | struct device_attribute *attr, | |
4a0b2b4d | 1001 | char *buf) |
734efb46 | 1002 | { |
2e197586 | 1003 | struct clocksource *src; |
5e2cb101 | 1004 | ssize_t count = 0; |
734efb46 | 1005 | |
75c5158f | 1006 | mutex_lock(&clocksource_mutex); |
2e197586 | 1007 | list_for_each_entry(src, &clocksource_list, list) { |
cd6d95d8 TG |
1008 | /* |
1009 | * Don't show non-HRES clocksource if the tick code is | |
1010 | * in one shot mode (highres=on or nohz=on) | |
1011 | */ | |
1012 | if (!tick_oneshot_mode_active() || | |
1013 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) | |
3f68535a | 1014 | count += snprintf(buf + count, |
5e2cb101 MX |
1015 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), |
1016 | "%s ", src->name); | |
734efb46 | 1017 | } |
75c5158f | 1018 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1019 | |
5e2cb101 MX |
1020 | count += snprintf(buf + count, |
1021 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); | |
734efb46 | 1022 | |
5e2cb101 | 1023 | return count; |
734efb46 JS |
1024 | } |
1025 | ||
1026 | /* | |
1027 | * Sysfs setup bits: | |
1028 | */ | |
d369a5d8 | 1029 | static DEVICE_ATTR(current_clocksource, 0644, sysfs_show_current_clocksources, |
f5f1a24a | 1030 | sysfs_override_clocksource); |
734efb46 | 1031 | |
7eaeb343 TG |
1032 | static DEVICE_ATTR(unbind_clocksource, 0200, NULL, sysfs_unbind_clocksource); |
1033 | ||
d369a5d8 | 1034 | static DEVICE_ATTR(available_clocksource, 0444, |
f5f1a24a | 1035 | sysfs_show_available_clocksources, NULL); |
734efb46 | 1036 | |
d369a5d8 | 1037 | static struct bus_type clocksource_subsys = { |
af5ca3f4 | 1038 | .name = "clocksource", |
d369a5d8 | 1039 | .dev_name = "clocksource", |
734efb46 JS |
1040 | }; |
1041 | ||
d369a5d8 | 1042 | static struct device device_clocksource = { |
734efb46 | 1043 | .id = 0, |
d369a5d8 | 1044 | .bus = &clocksource_subsys, |
734efb46 JS |
1045 | }; |
1046 | ||
ad596171 | 1047 | static int __init init_clocksource_sysfs(void) |
734efb46 | 1048 | { |
d369a5d8 | 1049 | int error = subsys_system_register(&clocksource_subsys, NULL); |
734efb46 JS |
1050 | |
1051 | if (!error) | |
d369a5d8 | 1052 | error = device_register(&device_clocksource); |
734efb46 | 1053 | if (!error) |
d369a5d8 | 1054 | error = device_create_file( |
734efb46 | 1055 | &device_clocksource, |
d369a5d8 | 1056 | &dev_attr_current_clocksource); |
7eaeb343 TG |
1057 | if (!error) |
1058 | error = device_create_file(&device_clocksource, | |
1059 | &dev_attr_unbind_clocksource); | |
734efb46 | 1060 | if (!error) |
d369a5d8 | 1061 | error = device_create_file( |
734efb46 | 1062 | &device_clocksource, |
d369a5d8 | 1063 | &dev_attr_available_clocksource); |
734efb46 JS |
1064 | return error; |
1065 | } | |
1066 | ||
1067 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 1068 | #endif /* CONFIG_SYSFS */ |
734efb46 JS |
1069 | |
1070 | /** | |
1071 | * boot_override_clocksource - boot clock override | |
1072 | * @str: override name | |
1073 | * | |
1074 | * Takes a clocksource= boot argument and uses it | |
1075 | * as the clocksource override name. | |
1076 | */ | |
1077 | static int __init boot_override_clocksource(char* str) | |
1078 | { | |
75c5158f | 1079 | mutex_lock(&clocksource_mutex); |
734efb46 JS |
1080 | if (str) |
1081 | strlcpy(override_name, str, sizeof(override_name)); | |
75c5158f | 1082 | mutex_unlock(&clocksource_mutex); |
734efb46 JS |
1083 | return 1; |
1084 | } | |
1085 | ||
1086 | __setup("clocksource=", boot_override_clocksource); | |
1087 | ||
1088 | /** | |
1089 | * boot_override_clock - Compatibility layer for deprecated boot option | |
1090 | * @str: override name | |
1091 | * | |
1092 | * DEPRECATED! Takes a clock= boot argument and uses it | |
1093 | * as the clocksource override name | |
1094 | */ | |
1095 | static int __init boot_override_clock(char* str) | |
1096 | { | |
5d0cf410 JS |
1097 | if (!strcmp(str, "pmtmr")) { |
1098 | printk("Warning: clock=pmtmr is deprecated. " | |
1099 | "Use clocksource=acpi_pm.\n"); | |
1100 | return boot_override_clocksource("acpi_pm"); | |
1101 | } | |
1102 | printk("Warning! clock= boot option is deprecated. " | |
1103 | "Use clocksource=xyz\n"); | |
734efb46 JS |
1104 | return boot_override_clocksource(str); |
1105 | } | |
1106 | ||
1107 | __setup("clock=", boot_override_clock); |