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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 | ||
45bbfe64 JP |
26 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
27 | ||
d369a5d8 | 28 | #include <linux/device.h> |
734efb46 | 29 | #include <linux/clocksource.h> |
734efb46 JS |
30 | #include <linux/init.h> |
31 | #include <linux/module.h> | |
dc29a365 | 32 | #include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */ |
79bf2bb3 | 33 | #include <linux/tick.h> |
01548f4d | 34 | #include <linux/kthread.h> |
734efb46 | 35 | |
c1797baf | 36 | #include "tick-internal.h" |
3a978377 | 37 | #include "timekeeping_internal.h" |
03e13cf5 | 38 | |
7d2f944a TG |
39 | /** |
40 | * clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks | |
41 | * @mult: pointer to mult variable | |
42 | * @shift: pointer to shift variable | |
43 | * @from: frequency to convert from | |
44 | * @to: frequency to convert to | |
5fdade95 | 45 | * @maxsec: guaranteed runtime conversion range in seconds |
7d2f944a TG |
46 | * |
47 | * The function evaluates the shift/mult pair for the scaled math | |
48 | * operations of clocksources and clockevents. | |
49 | * | |
50 | * @to and @from are frequency values in HZ. For clock sources @to is | |
51 | * NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock | |
52 | * event @to is the counter frequency and @from is NSEC_PER_SEC. | |
53 | * | |
5fdade95 | 54 | * The @maxsec conversion range argument controls the time frame in |
7d2f944a TG |
55 | * seconds which must be covered by the runtime conversion with the |
56 | * calculated mult and shift factors. This guarantees that no 64bit | |
57 | * overflow happens when the input value of the conversion is | |
58 | * multiplied with the calculated mult factor. Larger ranges may | |
59 | * reduce the conversion accuracy by chosing smaller mult and shift | |
60 | * factors. | |
61 | */ | |
62 | void | |
5fdade95 | 63 | clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 maxsec) |
7d2f944a TG |
64 | { |
65 | u64 tmp; | |
66 | u32 sft, sftacc= 32; | |
67 | ||
68 | /* | |
69 | * Calculate the shift factor which is limiting the conversion | |
70 | * range: | |
71 | */ | |
5fdade95 | 72 | tmp = ((u64)maxsec * from) >> 32; |
7d2f944a TG |
73 | while (tmp) { |
74 | tmp >>=1; | |
75 | sftacc--; | |
76 | } | |
77 | ||
78 | /* | |
79 | * Find the conversion shift/mult pair which has the best | |
80 | * accuracy and fits the maxsec conversion range: | |
81 | */ | |
82 | for (sft = 32; sft > 0; sft--) { | |
83 | tmp = (u64) to << sft; | |
b5776c4a | 84 | tmp += from / 2; |
7d2f944a TG |
85 | do_div(tmp, from); |
86 | if ((tmp >> sftacc) == 0) | |
87 | break; | |
88 | } | |
89 | *mult = tmp; | |
90 | *shift = sft; | |
91 | } | |
5304121a | 92 | EXPORT_SYMBOL_GPL(clocks_calc_mult_shift); |
7d2f944a | 93 | |
734efb46 JS |
94 | /*[Clocksource internal variables]--------- |
95 | * curr_clocksource: | |
f1b82746 | 96 | * currently selected clocksource. |
734efb46 JS |
97 | * clocksource_list: |
98 | * linked list with the registered clocksources | |
75c5158f MS |
99 | * clocksource_mutex: |
100 | * protects manipulations to curr_clocksource and the clocksource_list | |
734efb46 JS |
101 | * override_name: |
102 | * Name of the user-specified clocksource. | |
103 | */ | |
f1b82746 | 104 | static struct clocksource *curr_clocksource; |
734efb46 | 105 | static LIST_HEAD(clocksource_list); |
75c5158f | 106 | static DEFINE_MUTEX(clocksource_mutex); |
29b54078 | 107 | static char override_name[CS_NAME_LEN]; |
54a6bc0b | 108 | static int finished_booting; |
734efb46 | 109 | |
5d8b34fd | 110 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
f79e0258 | 111 | static void clocksource_watchdog_work(struct work_struct *work); |
332962f2 | 112 | static void clocksource_select(void); |
f79e0258 | 113 | |
5d8b34fd TG |
114 | static LIST_HEAD(watchdog_list); |
115 | static struct clocksource *watchdog; | |
116 | static struct timer_list watchdog_timer; | |
f79e0258 | 117 | static DECLARE_WORK(watchdog_work, clocksource_watchdog_work); |
5d8b34fd | 118 | static DEFINE_SPINLOCK(watchdog_lock); |
fb63a0eb | 119 | static int watchdog_running; |
9fb60336 | 120 | static atomic_t watchdog_reset_pending; |
b52f52a0 | 121 | |
01548f4d | 122 | static int clocksource_watchdog_kthread(void *data); |
d0981a1b | 123 | static void __clocksource_change_rating(struct clocksource *cs, int rating); |
c55c87c8 | 124 | |
5d8b34fd | 125 | /* |
35c35d1a | 126 | * Interval: 0.5sec Threshold: 0.0625s |
5d8b34fd TG |
127 | */ |
128 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
35c35d1a | 129 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) |
5d8b34fd | 130 | |
01548f4d MS |
131 | static void clocksource_watchdog_work(struct work_struct *work) |
132 | { | |
133 | /* | |
134 | * If kthread_run fails the next watchdog scan over the | |
135 | * watchdog_list will find the unstable clock again. | |
136 | */ | |
137 | kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog"); | |
138 | } | |
139 | ||
7285dd7f | 140 | static void __clocksource_unstable(struct clocksource *cs) |
5d8b34fd | 141 | { |
5d8b34fd | 142 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); |
c55c87c8 | 143 | cs->flags |= CLOCK_SOURCE_UNSTABLE; |
54a6bc0b TG |
144 | if (finished_booting) |
145 | schedule_work(&watchdog_work); | |
5d8b34fd TG |
146 | } |
147 | ||
7285dd7f TG |
148 | /** |
149 | * clocksource_mark_unstable - mark clocksource unstable via watchdog | |
150 | * @cs: clocksource to be marked unstable | |
151 | * | |
152 | * This function is called instead of clocksource_change_rating from | |
153 | * cpu hotplug code to avoid a deadlock between the clocksource mutex | |
154 | * and the cpu hotplug mutex. It defers the update of the clocksource | |
155 | * to the watchdog thread. | |
156 | */ | |
157 | void clocksource_mark_unstable(struct clocksource *cs) | |
158 | { | |
159 | unsigned long flags; | |
160 | ||
161 | spin_lock_irqsave(&watchdog_lock, flags); | |
162 | if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) { | |
163 | if (list_empty(&cs->wd_list)) | |
164 | list_add(&cs->wd_list, &watchdog_list); | |
165 | __clocksource_unstable(cs); | |
166 | } | |
167 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
168 | } | |
169 | ||
5d8b34fd TG |
170 | static void clocksource_watchdog(unsigned long data) |
171 | { | |
c55c87c8 | 172 | struct clocksource *cs; |
a5a1d1c2 | 173 | u64 csnow, wdnow, cslast, wdlast, delta; |
5d8b34fd | 174 | int64_t wd_nsec, cs_nsec; |
9fb60336 | 175 | int next_cpu, reset_pending; |
5d8b34fd TG |
176 | |
177 | spin_lock(&watchdog_lock); | |
fb63a0eb MS |
178 | if (!watchdog_running) |
179 | goto out; | |
5d8b34fd | 180 | |
9fb60336 TG |
181 | reset_pending = atomic_read(&watchdog_reset_pending); |
182 | ||
c55c87c8 MS |
183 | list_for_each_entry(cs, &watchdog_list, wd_list) { |
184 | ||
185 | /* Clocksource already marked unstable? */ | |
01548f4d | 186 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
54a6bc0b TG |
187 | if (finished_booting) |
188 | schedule_work(&watchdog_work); | |
c55c87c8 | 189 | continue; |
01548f4d | 190 | } |
c55c87c8 | 191 | |
b5199515 | 192 | local_irq_disable(); |
8e19608e | 193 | csnow = cs->read(cs); |
b5199515 TG |
194 | wdnow = watchdog->read(watchdog); |
195 | local_irq_enable(); | |
b52f52a0 | 196 | |
8cf4e750 | 197 | /* Clocksource initialized ? */ |
9fb60336 TG |
198 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) || |
199 | atomic_read(&watchdog_reset_pending)) { | |
8cf4e750 | 200 | cs->flags |= CLOCK_SOURCE_WATCHDOG; |
b5199515 TG |
201 | cs->wd_last = wdnow; |
202 | cs->cs_last = csnow; | |
b52f52a0 TG |
203 | continue; |
204 | } | |
205 | ||
3a978377 TG |
206 | delta = clocksource_delta(wdnow, cs->wd_last, watchdog->mask); |
207 | wd_nsec = clocksource_cyc2ns(delta, watchdog->mult, | |
208 | watchdog->shift); | |
b5199515 | 209 | |
3a978377 TG |
210 | delta = clocksource_delta(csnow, cs->cs_last, cs->mask); |
211 | cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift); | |
0b046b21 JS |
212 | wdlast = cs->wd_last; /* save these in case we print them */ |
213 | cslast = cs->cs_last; | |
b5199515 TG |
214 | cs->cs_last = csnow; |
215 | cs->wd_last = wdnow; | |
216 | ||
9fb60336 TG |
217 | if (atomic_read(&watchdog_reset_pending)) |
218 | continue; | |
219 | ||
b5199515 | 220 | /* Check the deviation from the watchdog clocksource. */ |
79211c8e | 221 | if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) { |
390dd67c SI |
222 | pr_warn("timekeeping watchdog on CPU%d: Marking clocksource '%s' as unstable because the skew is too large:\n", |
223 | smp_processor_id(), cs->name); | |
45bbfe64 | 224 | pr_warn(" '%s' wd_now: %llx wd_last: %llx mask: %llx\n", |
0b046b21 | 225 | watchdog->name, wdnow, wdlast, watchdog->mask); |
45bbfe64 | 226 | pr_warn(" '%s' cs_now: %llx cs_last: %llx mask: %llx\n", |
0b046b21 JS |
227 | cs->name, csnow, cslast, cs->mask); |
228 | __clocksource_unstable(cs); | |
8cf4e750 MS |
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)) { | |
332962f2 | 235 | /* Mark it valid for high-res. */ |
8cf4e750 | 236 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
332962f2 TG |
237 | |
238 | /* | |
239 | * clocksource_done_booting() will sort it if | |
240 | * finished_booting is not set yet. | |
241 | */ | |
242 | if (!finished_booting) | |
243 | continue; | |
244 | ||
8cf4e750 | 245 | /* |
332962f2 TG |
246 | * If this is not the current clocksource let |
247 | * the watchdog thread reselect it. Due to the | |
248 | * change to high res this clocksource might | |
249 | * be preferred now. If it is the current | |
250 | * clocksource let the tick code know about | |
251 | * that change. | |
8cf4e750 | 252 | */ |
332962f2 TG |
253 | if (cs != curr_clocksource) { |
254 | cs->flags |= CLOCK_SOURCE_RESELECT; | |
255 | schedule_work(&watchdog_work); | |
256 | } else { | |
257 | tick_clock_notify(); | |
258 | } | |
5d8b34fd TG |
259 | } |
260 | } | |
261 | ||
9fb60336 TG |
262 | /* |
263 | * We only clear the watchdog_reset_pending, when we did a | |
264 | * full cycle through all clocksources. | |
265 | */ | |
266 | if (reset_pending) | |
267 | atomic_dec(&watchdog_reset_pending); | |
268 | ||
c55c87c8 MS |
269 | /* |
270 | * Cycle through CPUs to check if the CPUs stay synchronized | |
271 | * to each other. | |
272 | */ | |
273 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); | |
274 | if (next_cpu >= nr_cpu_ids) | |
275 | next_cpu = cpumask_first(cpu_online_mask); | |
276 | watchdog_timer.expires += WATCHDOG_INTERVAL; | |
277 | add_timer_on(&watchdog_timer, next_cpu); | |
fb63a0eb | 278 | out: |
5d8b34fd TG |
279 | spin_unlock(&watchdog_lock); |
280 | } | |
0f8e8ef7 | 281 | |
fb63a0eb MS |
282 | static inline void clocksource_start_watchdog(void) |
283 | { | |
284 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) | |
285 | return; | |
286 | init_timer(&watchdog_timer); | |
287 | watchdog_timer.function = clocksource_watchdog; | |
fb63a0eb MS |
288 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; |
289 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); | |
290 | watchdog_running = 1; | |
291 | } | |
292 | ||
293 | static inline void clocksource_stop_watchdog(void) | |
294 | { | |
295 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) | |
296 | return; | |
297 | del_timer(&watchdog_timer); | |
298 | watchdog_running = 0; | |
299 | } | |
300 | ||
0f8e8ef7 MS |
301 | static inline void clocksource_reset_watchdog(void) |
302 | { | |
303 | struct clocksource *cs; | |
304 | ||
305 | list_for_each_entry(cs, &watchdog_list, wd_list) | |
306 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
307 | } | |
308 | ||
b52f52a0 TG |
309 | static void clocksource_resume_watchdog(void) |
310 | { | |
9fb60336 | 311 | atomic_inc(&watchdog_reset_pending); |
b52f52a0 TG |
312 | } |
313 | ||
fb63a0eb | 314 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
5d8b34fd | 315 | { |
5d8b34fd TG |
316 | unsigned long flags; |
317 | ||
318 | spin_lock_irqsave(&watchdog_lock, flags); | |
319 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
fb63a0eb | 320 | /* cs is a clocksource to be watched. */ |
5d8b34fd | 321 | list_add(&cs->wd_list, &watchdog_list); |
fb63a0eb | 322 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
948ac6d7 | 323 | } else { |
fb63a0eb | 324 | /* cs is a watchdog. */ |
948ac6d7 | 325 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
5d8b34fd | 326 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
bbf66d89 VK |
327 | } |
328 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
329 | } | |
330 | ||
331 | static void clocksource_select_watchdog(bool fallback) | |
332 | { | |
333 | struct clocksource *cs, *old_wd; | |
334 | unsigned long flags; | |
335 | ||
336 | spin_lock_irqsave(&watchdog_lock, flags); | |
337 | /* save current watchdog */ | |
338 | old_wd = watchdog; | |
339 | if (fallback) | |
340 | watchdog = NULL; | |
341 | ||
342 | list_for_each_entry(cs, &clocksource_list, list) { | |
343 | /* cs is a clocksource to be watched. */ | |
344 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) | |
345 | continue; | |
346 | ||
347 | /* Skip current if we were requested for a fallback. */ | |
348 | if (fallback && cs == old_wd) | |
349 | continue; | |
350 | ||
fb63a0eb | 351 | /* Pick the best watchdog. */ |
bbf66d89 | 352 | if (!watchdog || cs->rating > watchdog->rating) |
5d8b34fd | 353 | watchdog = cs; |
5d8b34fd | 354 | } |
bbf66d89 VK |
355 | /* If we failed to find a fallback restore the old one. */ |
356 | if (!watchdog) | |
357 | watchdog = old_wd; | |
358 | ||
359 | /* If we changed the watchdog we need to reset cycles. */ | |
360 | if (watchdog != old_wd) | |
361 | clocksource_reset_watchdog(); | |
362 | ||
fb63a0eb MS |
363 | /* Check if the watchdog timer needs to be started. */ |
364 | clocksource_start_watchdog(); | |
5d8b34fd TG |
365 | spin_unlock_irqrestore(&watchdog_lock, flags); |
366 | } | |
fb63a0eb MS |
367 | |
368 | static void clocksource_dequeue_watchdog(struct clocksource *cs) | |
369 | { | |
fb63a0eb MS |
370 | unsigned long flags; |
371 | ||
372 | spin_lock_irqsave(&watchdog_lock, flags); | |
a89c7edb TG |
373 | if (cs != watchdog) { |
374 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
375 | /* cs is a watched clocksource. */ | |
376 | list_del_init(&cs->wd_list); | |
377 | /* Check if the watchdog timer needs to be stopped. */ | |
378 | clocksource_stop_watchdog(); | |
fb63a0eb MS |
379 | } |
380 | } | |
fb63a0eb MS |
381 | spin_unlock_irqrestore(&watchdog_lock, flags); |
382 | } | |
383 | ||
332962f2 | 384 | static int __clocksource_watchdog_kthread(void) |
c55c87c8 MS |
385 | { |
386 | struct clocksource *cs, *tmp; | |
387 | unsigned long flags; | |
6ea41d25 | 388 | LIST_HEAD(unstable); |
332962f2 | 389 | int select = 0; |
c55c87c8 MS |
390 | |
391 | spin_lock_irqsave(&watchdog_lock, flags); | |
332962f2 | 392 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { |
c55c87c8 MS |
393 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
394 | list_del_init(&cs->wd_list); | |
6ea41d25 | 395 | list_add(&cs->wd_list, &unstable); |
332962f2 TG |
396 | select = 1; |
397 | } | |
398 | if (cs->flags & CLOCK_SOURCE_RESELECT) { | |
399 | cs->flags &= ~CLOCK_SOURCE_RESELECT; | |
400 | select = 1; | |
c55c87c8 | 401 | } |
332962f2 | 402 | } |
c55c87c8 MS |
403 | /* Check if the watchdog timer needs to be stopped. */ |
404 | clocksource_stop_watchdog(); | |
6ea41d25 TG |
405 | spin_unlock_irqrestore(&watchdog_lock, flags); |
406 | ||
407 | /* Needs to be done outside of watchdog lock */ | |
408 | list_for_each_entry_safe(cs, tmp, &unstable, wd_list) { | |
409 | list_del_init(&cs->wd_list); | |
d0981a1b | 410 | __clocksource_change_rating(cs, 0); |
6ea41d25 | 411 | } |
332962f2 TG |
412 | return select; |
413 | } | |
414 | ||
415 | static int clocksource_watchdog_kthread(void *data) | |
416 | { | |
417 | mutex_lock(&clocksource_mutex); | |
418 | if (__clocksource_watchdog_kthread()) | |
419 | clocksource_select(); | |
d0981a1b | 420 | mutex_unlock(&clocksource_mutex); |
01548f4d | 421 | return 0; |
c55c87c8 MS |
422 | } |
423 | ||
7eaeb343 TG |
424 | static bool clocksource_is_watchdog(struct clocksource *cs) |
425 | { | |
426 | return cs == watchdog; | |
427 | } | |
428 | ||
fb63a0eb MS |
429 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
430 | ||
431 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
5d8b34fd TG |
432 | { |
433 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
434 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
435 | } | |
b52f52a0 | 436 | |
bbf66d89 | 437 | static void clocksource_select_watchdog(bool fallback) { } |
fb63a0eb | 438 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
b52f52a0 | 439 | static inline void clocksource_resume_watchdog(void) { } |
332962f2 | 440 | static inline int __clocksource_watchdog_kthread(void) { return 0; } |
7eaeb343 | 441 | static bool clocksource_is_watchdog(struct clocksource *cs) { return false; } |
397bbf6d | 442 | void clocksource_mark_unstable(struct clocksource *cs) { } |
fb63a0eb MS |
443 | |
444 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ | |
5d8b34fd | 445 | |
c54a42b1 MD |
446 | /** |
447 | * clocksource_suspend - suspend the clocksource(s) | |
448 | */ | |
449 | void clocksource_suspend(void) | |
450 | { | |
451 | struct clocksource *cs; | |
452 | ||
453 | list_for_each_entry_reverse(cs, &clocksource_list, list) | |
454 | if (cs->suspend) | |
455 | cs->suspend(cs); | |
456 | } | |
457 | ||
b52f52a0 TG |
458 | /** |
459 | * clocksource_resume - resume the clocksource(s) | |
460 | */ | |
461 | void clocksource_resume(void) | |
462 | { | |
2e197586 | 463 | struct clocksource *cs; |
b52f52a0 | 464 | |
75c5158f | 465 | list_for_each_entry(cs, &clocksource_list, list) |
b52f52a0 | 466 | if (cs->resume) |
17622339 | 467 | cs->resume(cs); |
b52f52a0 TG |
468 | |
469 | clocksource_resume_watchdog(); | |
b52f52a0 TG |
470 | } |
471 | ||
7c3078b6 JW |
472 | /** |
473 | * clocksource_touch_watchdog - Update watchdog | |
474 | * | |
475 | * Update the watchdog after exception contexts such as kgdb so as not | |
7b7422a5 TG |
476 | * to incorrectly trip the watchdog. This might fail when the kernel |
477 | * was stopped in code which holds watchdog_lock. | |
7c3078b6 JW |
478 | */ |
479 | void clocksource_touch_watchdog(void) | |
480 | { | |
481 | clocksource_resume_watchdog(); | |
482 | } | |
483 | ||
d65670a7 JS |
484 | /** |
485 | * clocksource_max_adjustment- Returns max adjustment amount | |
486 | * @cs: Pointer to clocksource | |
487 | * | |
488 | */ | |
489 | static u32 clocksource_max_adjustment(struct clocksource *cs) | |
490 | { | |
491 | u64 ret; | |
492 | /* | |
88b28adf | 493 | * We won't try to correct for more than 11% adjustments (110,000 ppm), |
d65670a7 JS |
494 | */ |
495 | ret = (u64)cs->mult * 11; | |
496 | do_div(ret,100); | |
497 | return (u32)ret; | |
498 | } | |
499 | ||
98962465 | 500 | /** |
87d8b9eb SB |
501 | * clocks_calc_max_nsecs - Returns maximum nanoseconds that can be converted |
502 | * @mult: cycle to nanosecond multiplier | |
503 | * @shift: cycle to nanosecond divisor (power of two) | |
504 | * @maxadj: maximum adjustment value to mult (~11%) | |
505 | * @mask: bitmask for two's complement subtraction of non 64 bit counters | |
fb82fe2f JS |
506 | * @max_cyc: maximum cycle value before potential overflow (does not include |
507 | * any safety margin) | |
362fde04 | 508 | * |
8e56f33f JS |
509 | * NOTE: This function includes a safety margin of 50%, in other words, we |
510 | * return half the number of nanoseconds the hardware counter can technically | |
511 | * cover. This is done so that we can potentially detect problems caused by | |
512 | * delayed timers or bad hardware, which might result in time intervals that | |
571af55a | 513 | * are larger than what the math used can handle without overflows. |
98962465 | 514 | */ |
fb82fe2f | 515 | u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cyc) |
98962465 JH |
516 | { |
517 | u64 max_nsecs, max_cycles; | |
518 | ||
519 | /* | |
520 | * Calculate the maximum number of cycles that we can pass to the | |
6086e346 | 521 | * cyc2ns() function without overflowing a 64-bit result. |
98962465 | 522 | */ |
6086e346 JS |
523 | max_cycles = ULLONG_MAX; |
524 | do_div(max_cycles, mult+maxadj); | |
98962465 JH |
525 | |
526 | /* | |
527 | * The actual maximum number of cycles we can defer the clocksource is | |
87d8b9eb | 528 | * determined by the minimum of max_cycles and mask. |
d65670a7 JS |
529 | * Note: Here we subtract the maxadj to make sure we don't sleep for |
530 | * too long if there's a large negative adjustment. | |
98962465 | 531 | */ |
87d8b9eb SB |
532 | max_cycles = min(max_cycles, mask); |
533 | max_nsecs = clocksource_cyc2ns(max_cycles, mult - maxadj, shift); | |
534 | ||
fb82fe2f JS |
535 | /* return the max_cycles value as well if requested */ |
536 | if (max_cyc) | |
537 | *max_cyc = max_cycles; | |
538 | ||
362fde04 JS |
539 | /* Return 50% of the actual maximum, so we can detect bad values */ |
540 | max_nsecs >>= 1; | |
541 | ||
87d8b9eb SB |
542 | return max_nsecs; |
543 | } | |
544 | ||
545 | /** | |
fb82fe2f JS |
546 | * clocksource_update_max_deferment - Updates the clocksource max_idle_ns & max_cycles |
547 | * @cs: Pointer to clocksource to be updated | |
87d8b9eb SB |
548 | * |
549 | */ | |
fb82fe2f | 550 | static inline void clocksource_update_max_deferment(struct clocksource *cs) |
87d8b9eb | 551 | { |
fb82fe2f JS |
552 | cs->max_idle_ns = clocks_calc_max_nsecs(cs->mult, cs->shift, |
553 | cs->maxadj, cs->mask, | |
554 | &cs->max_cycles); | |
98962465 JH |
555 | } |
556 | ||
592913ec | 557 | #ifndef CONFIG_ARCH_USES_GETTIMEOFFSET |
734efb46 | 558 | |
f5a2e343 | 559 | static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur) |
5d33b883 TG |
560 | { |
561 | struct clocksource *cs; | |
562 | ||
563 | if (!finished_booting || list_empty(&clocksource_list)) | |
564 | return NULL; | |
565 | ||
566 | /* | |
567 | * We pick the clocksource with the highest rating. If oneshot | |
568 | * mode is active, we pick the highres valid clocksource with | |
569 | * the best rating. | |
570 | */ | |
571 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
572 | if (skipcur && cs == curr_clocksource) |
573 | continue; | |
5d33b883 TG |
574 | if (oneshot && !(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES)) |
575 | continue; | |
576 | return cs; | |
577 | } | |
578 | return NULL; | |
579 | } | |
580 | ||
f5a2e343 | 581 | static void __clocksource_select(bool skipcur) |
734efb46 | 582 | { |
5d33b883 | 583 | bool oneshot = tick_oneshot_mode_active(); |
f1b82746 | 584 | struct clocksource *best, *cs; |
5d8b34fd | 585 | |
5d33b883 | 586 | /* Find the best suitable clocksource */ |
f5a2e343 | 587 | best = clocksource_find_best(oneshot, skipcur); |
5d33b883 | 588 | if (!best) |
f1b82746 | 589 | return; |
5d33b883 | 590 | |
f1b82746 MS |
591 | /* Check for the override clocksource. */ |
592 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
593 | if (skipcur && cs == curr_clocksource) |
594 | continue; | |
f1b82746 MS |
595 | if (strcmp(cs->name, override_name) != 0) |
596 | continue; | |
597 | /* | |
598 | * Check to make sure we don't switch to a non-highres | |
599 | * capable clocksource if the tick code is in oneshot | |
600 | * mode (highres or nohz) | |
601 | */ | |
5d33b883 | 602 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && oneshot) { |
f1b82746 | 603 | /* Override clocksource cannot be used. */ |
36374583 KW |
604 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
605 | pr_warn("Override clocksource %s is unstable and not HRT compatible - cannot switch while in HRT/NOHZ mode\n", | |
606 | cs->name); | |
607 | override_name[0] = 0; | |
608 | } else { | |
609 | /* | |
610 | * The override cannot be currently verified. | |
611 | * Deferring to let the watchdog check. | |
612 | */ | |
613 | pr_info("Override clocksource %s is not currently HRT compatible - deferring\n", | |
614 | cs->name); | |
615 | } | |
f1b82746 MS |
616 | } else |
617 | /* Override clocksource can be used. */ | |
618 | best = cs; | |
619 | break; | |
620 | } | |
ba919d1c TG |
621 | |
622 | if (curr_clocksource != best && !timekeeping_notify(best)) { | |
623 | pr_info("Switched to clocksource %s\n", best->name); | |
75c5158f | 624 | curr_clocksource = best; |
75c5158f | 625 | } |
f1b82746 | 626 | } |
734efb46 | 627 | |
f5a2e343 TG |
628 | /** |
629 | * clocksource_select - Select the best clocksource available | |
630 | * | |
631 | * Private function. Must hold clocksource_mutex when called. | |
632 | * | |
633 | * Select the clocksource with the best rating, or the clocksource, | |
634 | * which is selected by userspace override. | |
635 | */ | |
636 | static void clocksource_select(void) | |
637 | { | |
cfed432d | 638 | __clocksource_select(false); |
f5a2e343 TG |
639 | } |
640 | ||
7eaeb343 TG |
641 | static void clocksource_select_fallback(void) |
642 | { | |
cfed432d | 643 | __clocksource_select(true); |
7eaeb343 TG |
644 | } |
645 | ||
592913ec | 646 | #else /* !CONFIG_ARCH_USES_GETTIMEOFFSET */ |
54a6bc0b | 647 | static inline void clocksource_select(void) { } |
1eaff672 | 648 | static inline void clocksource_select_fallback(void) { } |
54a6bc0b TG |
649 | |
650 | #endif | |
651 | ||
75c5158f MS |
652 | /* |
653 | * clocksource_done_booting - Called near the end of core bootup | |
654 | * | |
655 | * Hack to avoid lots of clocksource churn at boot time. | |
656 | * We use fs_initcall because we want this to start before | |
657 | * device_initcall but after subsys_initcall. | |
658 | */ | |
659 | static int __init clocksource_done_booting(void) | |
660 | { | |
ad6759fb JS |
661 | mutex_lock(&clocksource_mutex); |
662 | curr_clocksource = clocksource_default_clock(); | |
75c5158f | 663 | finished_booting = 1; |
54a6bc0b TG |
664 | /* |
665 | * Run the watchdog first to eliminate unstable clock sources | |
666 | */ | |
332962f2 | 667 | __clocksource_watchdog_kthread(); |
75c5158f | 668 | clocksource_select(); |
e6c73305 | 669 | mutex_unlock(&clocksource_mutex); |
75c5158f MS |
670 | return 0; |
671 | } | |
672 | fs_initcall(clocksource_done_booting); | |
673 | ||
92c7e002 TG |
674 | /* |
675 | * Enqueue the clocksource sorted by rating | |
734efb46 | 676 | */ |
f1b82746 | 677 | static void clocksource_enqueue(struct clocksource *cs) |
734efb46 | 678 | { |
f1b82746 MS |
679 | struct list_head *entry = &clocksource_list; |
680 | struct clocksource *tmp; | |
92c7e002 | 681 | |
0fb71d34 | 682 | list_for_each_entry(tmp, &clocksource_list, list) { |
92c7e002 | 683 | /* Keep track of the place, where to insert */ |
0fb71d34 MH |
684 | if (tmp->rating < cs->rating) |
685 | break; | |
686 | entry = &tmp->list; | |
687 | } | |
f1b82746 | 688 | list_add(&cs->list, entry); |
734efb46 JS |
689 | } |
690 | ||
d7e81c26 | 691 | /** |
fba9e072 | 692 | * __clocksource_update_freq_scale - Used update clocksource with new freq |
b1b73d09 | 693 | * @cs: clocksource to be registered |
d7e81c26 JS |
694 | * @scale: Scale factor multiplied against freq to get clocksource hz |
695 | * @freq: clocksource frequency (cycles per second) divided by scale | |
696 | * | |
852db46d | 697 | * This should only be called from the clocksource->enable() method. |
d7e81c26 JS |
698 | * |
699 | * This *SHOULD NOT* be called directly! Please use the | |
fba9e072 JS |
700 | * __clocksource_update_freq_hz() or __clocksource_update_freq_khz() helper |
701 | * functions. | |
d7e81c26 | 702 | */ |
fba9e072 | 703 | void __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq) |
d7e81c26 | 704 | { |
c0e299b1 | 705 | u64 sec; |
f8935983 | 706 | |
d7e81c26 | 707 | /* |
f8935983 JS |
708 | * Default clocksources are *special* and self-define their mult/shift. |
709 | * But, you're not special, so you should specify a freq value. | |
d7e81c26 | 710 | */ |
f8935983 JS |
711 | if (freq) { |
712 | /* | |
713 | * Calc the maximum number of seconds which we can run before | |
714 | * wrapping around. For clocksources which have a mask > 32-bit | |
715 | * we need to limit the max sleep time to have a good | |
716 | * conversion precision. 10 minutes is still a reasonable | |
717 | * amount. That results in a shift value of 24 for a | |
718 | * clocksource with mask >= 40-bit and f >= 4GHz. That maps to | |
719 | * ~ 0.06ppm granularity for NTP. | |
720 | */ | |
721 | sec = cs->mask; | |
722 | do_div(sec, freq); | |
723 | do_div(sec, scale); | |
724 | if (!sec) | |
725 | sec = 1; | |
726 | else if (sec > 600 && cs->mask > UINT_MAX) | |
727 | sec = 600; | |
728 | ||
729 | clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, | |
730 | NSEC_PER_SEC / scale, sec * scale); | |
731 | } | |
d65670a7 | 732 | /* |
362fde04 JS |
733 | * Ensure clocksources that have large 'mult' values don't overflow |
734 | * when adjusted. | |
d65670a7 JS |
735 | */ |
736 | cs->maxadj = clocksource_max_adjustment(cs); | |
f8935983 JS |
737 | while (freq && ((cs->mult + cs->maxadj < cs->mult) |
738 | || (cs->mult - cs->maxadj > cs->mult))) { | |
d65670a7 JS |
739 | cs->mult >>= 1; |
740 | cs->shift--; | |
741 | cs->maxadj = clocksource_max_adjustment(cs); | |
742 | } | |
743 | ||
f8935983 JS |
744 | /* |
745 | * Only warn for *special* clocksources that self-define | |
746 | * their mult/shift values and don't specify a freq. | |
747 | */ | |
748 | WARN_ONCE(cs->mult + cs->maxadj < cs->mult, | |
749 | "timekeeping: Clocksource %s might overflow on 11%% adjustment\n", | |
750 | cs->name); | |
751 | ||
fb82fe2f | 752 | clocksource_update_max_deferment(cs); |
8cc8c525 | 753 | |
45bbfe64 JP |
754 | pr_info("%s: mask: 0x%llx max_cycles: 0x%llx, max_idle_ns: %lld ns\n", |
755 | cs->name, cs->mask, cs->max_cycles, cs->max_idle_ns); | |
852db46d | 756 | } |
fba9e072 | 757 | EXPORT_SYMBOL_GPL(__clocksource_update_freq_scale); |
852db46d JS |
758 | |
759 | /** | |
760 | * __clocksource_register_scale - Used to install new clocksources | |
b1b73d09 | 761 | * @cs: clocksource to be registered |
852db46d JS |
762 | * @scale: Scale factor multiplied against freq to get clocksource hz |
763 | * @freq: clocksource frequency (cycles per second) divided by scale | |
764 | * | |
765 | * Returns -EBUSY if registration fails, zero otherwise. | |
766 | * | |
767 | * This *SHOULD NOT* be called directly! Please use the | |
768 | * clocksource_register_hz() or clocksource_register_khz helper functions. | |
769 | */ | |
770 | int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) | |
771 | { | |
772 | ||
b595076a | 773 | /* Initialize mult/shift and max_idle_ns */ |
fba9e072 | 774 | __clocksource_update_freq_scale(cs, scale, freq); |
d7e81c26 | 775 | |
be278e98 | 776 | /* Add clocksource to the clocksource list */ |
d7e81c26 JS |
777 | mutex_lock(&clocksource_mutex); |
778 | clocksource_enqueue(cs); | |
d7e81c26 | 779 | clocksource_enqueue_watchdog(cs); |
e05b2efb | 780 | clocksource_select(); |
bbf66d89 | 781 | clocksource_select_watchdog(false); |
d7e81c26 JS |
782 | mutex_unlock(&clocksource_mutex); |
783 | return 0; | |
784 | } | |
785 | EXPORT_SYMBOL_GPL(__clocksource_register_scale); | |
786 | ||
d0981a1b TG |
787 | static void __clocksource_change_rating(struct clocksource *cs, int rating) |
788 | { | |
789 | list_del(&cs->list); | |
790 | cs->rating = rating; | |
791 | clocksource_enqueue(cs); | |
d0981a1b TG |
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); |
332962f2 | 803 | clocksource_select(); |
bbf66d89 | 804 | clocksource_select_watchdog(false); |
75c5158f | 805 | mutex_unlock(&clocksource_mutex); |
734efb46 | 806 | } |
fb63a0eb | 807 | EXPORT_SYMBOL(clocksource_change_rating); |
734efb46 | 808 | |
7eaeb343 TG |
809 | /* |
810 | * Unbind clocksource @cs. Called with clocksource_mutex held | |
811 | */ | |
812 | static int clocksource_unbind(struct clocksource *cs) | |
813 | { | |
bbf66d89 VK |
814 | if (clocksource_is_watchdog(cs)) { |
815 | /* Select and try to install a replacement watchdog. */ | |
816 | clocksource_select_watchdog(true); | |
817 | if (clocksource_is_watchdog(cs)) | |
818 | return -EBUSY; | |
819 | } | |
7eaeb343 TG |
820 | |
821 | if (cs == curr_clocksource) { | |
822 | /* Select and try to install a replacement clock source */ | |
823 | clocksource_select_fallback(); | |
824 | if (curr_clocksource == cs) | |
825 | return -EBUSY; | |
826 | } | |
827 | clocksource_dequeue_watchdog(cs); | |
828 | list_del_init(&cs->list); | |
829 | return 0; | |
830 | } | |
831 | ||
4713e22c TG |
832 | /** |
833 | * clocksource_unregister - remove a registered clocksource | |
b1b73d09 | 834 | * @cs: clocksource to be unregistered |
4713e22c | 835 | */ |
a89c7edb | 836 | int clocksource_unregister(struct clocksource *cs) |
4713e22c | 837 | { |
a89c7edb TG |
838 | int ret = 0; |
839 | ||
75c5158f | 840 | mutex_lock(&clocksource_mutex); |
a89c7edb TG |
841 | if (!list_empty(&cs->list)) |
842 | ret = clocksource_unbind(cs); | |
75c5158f | 843 | mutex_unlock(&clocksource_mutex); |
a89c7edb | 844 | return ret; |
4713e22c | 845 | } |
fb63a0eb | 846 | EXPORT_SYMBOL(clocksource_unregister); |
4713e22c | 847 | |
2b013700 | 848 | #ifdef CONFIG_SYSFS |
734efb46 JS |
849 | /** |
850 | * sysfs_show_current_clocksources - sysfs interface for current clocksource | |
851 | * @dev: unused | |
b1b73d09 | 852 | * @attr: unused |
734efb46 JS |
853 | * @buf: char buffer to be filled with clocksource list |
854 | * | |
855 | * Provides sysfs interface for listing current clocksource. | |
856 | */ | |
857 | static ssize_t | |
d369a5d8 KS |
858 | sysfs_show_current_clocksources(struct device *dev, |
859 | struct device_attribute *attr, char *buf) | |
734efb46 | 860 | { |
5e2cb101 | 861 | ssize_t count = 0; |
734efb46 | 862 | |
75c5158f | 863 | mutex_lock(&clocksource_mutex); |
5e2cb101 | 864 | count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); |
75c5158f | 865 | mutex_unlock(&clocksource_mutex); |
734efb46 | 866 | |
5e2cb101 | 867 | return count; |
734efb46 JS |
868 | } |
869 | ||
891292a7 | 870 | ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt) |
29b54078 TG |
871 | { |
872 | size_t ret = cnt; | |
873 | ||
874 | /* strings from sysfs write are not 0 terminated! */ | |
875 | if (!cnt || cnt >= CS_NAME_LEN) | |
876 | return -EINVAL; | |
877 | ||
878 | /* strip of \n: */ | |
879 | if (buf[cnt-1] == '\n') | |
880 | cnt--; | |
881 | if (cnt > 0) | |
882 | memcpy(dst, buf, cnt); | |
883 | dst[cnt] = 0; | |
884 | return ret; | |
885 | } | |
886 | ||
734efb46 JS |
887 | /** |
888 | * sysfs_override_clocksource - interface for manually overriding clocksource | |
889 | * @dev: unused | |
b1b73d09 | 890 | * @attr: unused |
734efb46 JS |
891 | * @buf: name of override clocksource |
892 | * @count: length of buffer | |
893 | * | |
894 | * Takes input from sysfs interface for manually overriding the default | |
b71a8eb0 | 895 | * clocksource selection. |
734efb46 | 896 | */ |
d369a5d8 KS |
897 | static ssize_t sysfs_override_clocksource(struct device *dev, |
898 | struct device_attribute *attr, | |
734efb46 JS |
899 | const char *buf, size_t count) |
900 | { | |
233bcb41 | 901 | ssize_t ret; |
734efb46 | 902 | |
75c5158f | 903 | mutex_lock(&clocksource_mutex); |
734efb46 | 904 | |
03e13cf5 | 905 | ret = sysfs_get_uname(buf, override_name, count); |
29b54078 TG |
906 | if (ret >= 0) |
907 | clocksource_select(); | |
734efb46 | 908 | |
75c5158f | 909 | mutex_unlock(&clocksource_mutex); |
734efb46 JS |
910 | |
911 | return ret; | |
912 | } | |
913 | ||
7eaeb343 TG |
914 | /** |
915 | * sysfs_unbind_current_clocksource - interface for manually unbinding clocksource | |
916 | * @dev: unused | |
917 | * @attr: unused | |
918 | * @buf: unused | |
919 | * @count: length of buffer | |
920 | * | |
921 | * Takes input from sysfs interface for manually unbinding a clocksource. | |
922 | */ | |
923 | static ssize_t sysfs_unbind_clocksource(struct device *dev, | |
924 | struct device_attribute *attr, | |
925 | const char *buf, size_t count) | |
926 | { | |
927 | struct clocksource *cs; | |
928 | char name[CS_NAME_LEN]; | |
233bcb41 | 929 | ssize_t ret; |
7eaeb343 | 930 | |
03e13cf5 | 931 | ret = sysfs_get_uname(buf, name, count); |
7eaeb343 TG |
932 | if (ret < 0) |
933 | return ret; | |
934 | ||
935 | ret = -ENODEV; | |
936 | mutex_lock(&clocksource_mutex); | |
937 | list_for_each_entry(cs, &clocksource_list, list) { | |
938 | if (strcmp(cs->name, name)) | |
939 | continue; | |
940 | ret = clocksource_unbind(cs); | |
941 | break; | |
942 | } | |
943 | mutex_unlock(&clocksource_mutex); | |
944 | ||
945 | return ret ? ret : count; | |
946 | } | |
947 | ||
734efb46 JS |
948 | /** |
949 | * sysfs_show_available_clocksources - sysfs interface for listing clocksource | |
950 | * @dev: unused | |
b1b73d09 | 951 | * @attr: unused |
734efb46 JS |
952 | * @buf: char buffer to be filled with clocksource list |
953 | * | |
954 | * Provides sysfs interface for listing registered clocksources | |
955 | */ | |
956 | static ssize_t | |
d369a5d8 KS |
957 | sysfs_show_available_clocksources(struct device *dev, |
958 | struct device_attribute *attr, | |
4a0b2b4d | 959 | char *buf) |
734efb46 | 960 | { |
2e197586 | 961 | struct clocksource *src; |
5e2cb101 | 962 | ssize_t count = 0; |
734efb46 | 963 | |
75c5158f | 964 | mutex_lock(&clocksource_mutex); |
2e197586 | 965 | list_for_each_entry(src, &clocksource_list, list) { |
cd6d95d8 TG |
966 | /* |
967 | * Don't show non-HRES clocksource if the tick code is | |
968 | * in one shot mode (highres=on or nohz=on) | |
969 | */ | |
970 | if (!tick_oneshot_mode_active() || | |
971 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) | |
3f68535a | 972 | count += snprintf(buf + count, |
5e2cb101 MX |
973 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), |
974 | "%s ", src->name); | |
734efb46 | 975 | } |
75c5158f | 976 | mutex_unlock(&clocksource_mutex); |
734efb46 | 977 | |
5e2cb101 MX |
978 | count += snprintf(buf + count, |
979 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); | |
734efb46 | 980 | |
5e2cb101 | 981 | return count; |
734efb46 JS |
982 | } |
983 | ||
984 | /* | |
985 | * Sysfs setup bits: | |
986 | */ | |
d369a5d8 | 987 | static DEVICE_ATTR(current_clocksource, 0644, sysfs_show_current_clocksources, |
f5f1a24a | 988 | sysfs_override_clocksource); |
734efb46 | 989 | |
7eaeb343 TG |
990 | static DEVICE_ATTR(unbind_clocksource, 0200, NULL, sysfs_unbind_clocksource); |
991 | ||
d369a5d8 | 992 | static DEVICE_ATTR(available_clocksource, 0444, |
f5f1a24a | 993 | sysfs_show_available_clocksources, NULL); |
734efb46 | 994 | |
d369a5d8 | 995 | static struct bus_type clocksource_subsys = { |
af5ca3f4 | 996 | .name = "clocksource", |
d369a5d8 | 997 | .dev_name = "clocksource", |
734efb46 JS |
998 | }; |
999 | ||
d369a5d8 | 1000 | static struct device device_clocksource = { |
734efb46 | 1001 | .id = 0, |
d369a5d8 | 1002 | .bus = &clocksource_subsys, |
734efb46 JS |
1003 | }; |
1004 | ||
ad596171 | 1005 | static int __init init_clocksource_sysfs(void) |
734efb46 | 1006 | { |
d369a5d8 | 1007 | int error = subsys_system_register(&clocksource_subsys, NULL); |
734efb46 JS |
1008 | |
1009 | if (!error) | |
d369a5d8 | 1010 | error = device_register(&device_clocksource); |
734efb46 | 1011 | if (!error) |
d369a5d8 | 1012 | error = device_create_file( |
734efb46 | 1013 | &device_clocksource, |
d369a5d8 | 1014 | &dev_attr_current_clocksource); |
7eaeb343 TG |
1015 | if (!error) |
1016 | error = device_create_file(&device_clocksource, | |
1017 | &dev_attr_unbind_clocksource); | |
734efb46 | 1018 | if (!error) |
d369a5d8 | 1019 | error = device_create_file( |
734efb46 | 1020 | &device_clocksource, |
d369a5d8 | 1021 | &dev_attr_available_clocksource); |
734efb46 JS |
1022 | return error; |
1023 | } | |
1024 | ||
1025 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 1026 | #endif /* CONFIG_SYSFS */ |
734efb46 JS |
1027 | |
1028 | /** | |
1029 | * boot_override_clocksource - boot clock override | |
1030 | * @str: override name | |
1031 | * | |
1032 | * Takes a clocksource= boot argument and uses it | |
1033 | * as the clocksource override name. | |
1034 | */ | |
1035 | static int __init boot_override_clocksource(char* str) | |
1036 | { | |
75c5158f | 1037 | mutex_lock(&clocksource_mutex); |
734efb46 JS |
1038 | if (str) |
1039 | strlcpy(override_name, str, sizeof(override_name)); | |
75c5158f | 1040 | mutex_unlock(&clocksource_mutex); |
734efb46 JS |
1041 | return 1; |
1042 | } | |
1043 | ||
1044 | __setup("clocksource=", boot_override_clocksource); | |
1045 | ||
1046 | /** | |
1047 | * boot_override_clock - Compatibility layer for deprecated boot option | |
1048 | * @str: override name | |
1049 | * | |
1050 | * DEPRECATED! Takes a clock= boot argument and uses it | |
1051 | * as the clocksource override name | |
1052 | */ | |
1053 | static int __init boot_override_clock(char* str) | |
1054 | { | |
5d0cf410 | 1055 | if (!strcmp(str, "pmtmr")) { |
45bbfe64 | 1056 | pr_warn("clock=pmtmr is deprecated - use clocksource=acpi_pm\n"); |
5d0cf410 JS |
1057 | return boot_override_clocksource("acpi_pm"); |
1058 | } | |
45bbfe64 | 1059 | pr_warn("clock= boot option is deprecated - use clocksource=xyz\n"); |
734efb46 JS |
1060 | return boot_override_clocksource(str); |
1061 | } | |
1062 | ||
1063 | __setup("clock=", boot_override_clock); |