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