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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 | } | |
92 | ||
734efb46 JS |
93 | /*[Clocksource internal variables]--------- |
94 | * curr_clocksource: | |
f1b82746 | 95 | * currently selected clocksource. |
734efb46 JS |
96 | * clocksource_list: |
97 | * linked list with the registered clocksources | |
75c5158f MS |
98 | * clocksource_mutex: |
99 | * protects manipulations to curr_clocksource and the clocksource_list | |
734efb46 JS |
100 | * override_name: |
101 | * Name of the user-specified clocksource. | |
102 | */ | |
f1b82746 | 103 | static struct clocksource *curr_clocksource; |
734efb46 | 104 | static LIST_HEAD(clocksource_list); |
75c5158f | 105 | static DEFINE_MUTEX(clocksource_mutex); |
29b54078 | 106 | static char override_name[CS_NAME_LEN]; |
54a6bc0b | 107 | static int finished_booting; |
734efb46 | 108 | |
5d8b34fd | 109 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
f79e0258 | 110 | static void clocksource_watchdog_work(struct work_struct *work); |
332962f2 | 111 | static void clocksource_select(void); |
f79e0258 | 112 | |
5d8b34fd TG |
113 | static LIST_HEAD(watchdog_list); |
114 | static struct clocksource *watchdog; | |
115 | static struct timer_list watchdog_timer; | |
f79e0258 | 116 | static DECLARE_WORK(watchdog_work, clocksource_watchdog_work); |
5d8b34fd | 117 | static DEFINE_SPINLOCK(watchdog_lock); |
fb63a0eb | 118 | static int watchdog_running; |
9fb60336 | 119 | static atomic_t watchdog_reset_pending; |
b52f52a0 | 120 | |
01548f4d | 121 | static int clocksource_watchdog_kthread(void *data); |
d0981a1b | 122 | static void __clocksource_change_rating(struct clocksource *cs, int rating); |
c55c87c8 | 123 | |
5d8b34fd | 124 | /* |
35c35d1a | 125 | * Interval: 0.5sec Threshold: 0.0625s |
5d8b34fd TG |
126 | */ |
127 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
35c35d1a | 128 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) |
5d8b34fd | 129 | |
01548f4d MS |
130 | static void clocksource_watchdog_work(struct work_struct *work) |
131 | { | |
132 | /* | |
133 | * If kthread_run fails the next watchdog scan over the | |
134 | * watchdog_list will find the unstable clock again. | |
135 | */ | |
136 | kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog"); | |
137 | } | |
138 | ||
7285dd7f | 139 | static void __clocksource_unstable(struct clocksource *cs) |
5d8b34fd | 140 | { |
5d8b34fd | 141 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); |
c55c87c8 | 142 | cs->flags |= CLOCK_SOURCE_UNSTABLE; |
54a6bc0b TG |
143 | if (finished_booting) |
144 | schedule_work(&watchdog_work); | |
5d8b34fd TG |
145 | } |
146 | ||
7285dd7f TG |
147 | /** |
148 | * clocksource_mark_unstable - mark clocksource unstable via watchdog | |
149 | * @cs: clocksource to be marked unstable | |
150 | * | |
151 | * This function is called instead of clocksource_change_rating from | |
152 | * cpu hotplug code to avoid a deadlock between the clocksource mutex | |
153 | * and the cpu hotplug mutex. It defers the update of the clocksource | |
154 | * to the watchdog thread. | |
155 | */ | |
156 | void clocksource_mark_unstable(struct clocksource *cs) | |
157 | { | |
158 | unsigned long flags; | |
159 | ||
160 | spin_lock_irqsave(&watchdog_lock, flags); | |
161 | if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) { | |
162 | if (list_empty(&cs->wd_list)) | |
163 | list_add(&cs->wd_list, &watchdog_list); | |
164 | __clocksource_unstable(cs); | |
165 | } | |
166 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
167 | } | |
168 | ||
5d8b34fd TG |
169 | static void clocksource_watchdog(unsigned long data) |
170 | { | |
c55c87c8 | 171 | struct clocksource *cs; |
0b046b21 | 172 | cycle_t csnow, wdnow, cslast, wdlast, delta; |
5d8b34fd | 173 | int64_t wd_nsec, cs_nsec; |
9fb60336 | 174 | int next_cpu, reset_pending; |
5d8b34fd TG |
175 | |
176 | spin_lock(&watchdog_lock); | |
fb63a0eb MS |
177 | if (!watchdog_running) |
178 | goto out; | |
5d8b34fd | 179 | |
9fb60336 TG |
180 | reset_pending = atomic_read(&watchdog_reset_pending); |
181 | ||
c55c87c8 MS |
182 | list_for_each_entry(cs, &watchdog_list, wd_list) { |
183 | ||
184 | /* Clocksource already marked unstable? */ | |
01548f4d | 185 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
54a6bc0b TG |
186 | if (finished_booting) |
187 | schedule_work(&watchdog_work); | |
c55c87c8 | 188 | continue; |
01548f4d | 189 | } |
c55c87c8 | 190 | |
b5199515 | 191 | local_irq_disable(); |
8e19608e | 192 | csnow = cs->read(cs); |
b5199515 TG |
193 | wdnow = watchdog->read(watchdog); |
194 | local_irq_enable(); | |
b52f52a0 | 195 | |
8cf4e750 | 196 | /* Clocksource initialized ? */ |
9fb60336 TG |
197 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) || |
198 | atomic_read(&watchdog_reset_pending)) { | |
8cf4e750 | 199 | cs->flags |= CLOCK_SOURCE_WATCHDOG; |
b5199515 TG |
200 | cs->wd_last = wdnow; |
201 | cs->cs_last = csnow; | |
b52f52a0 TG |
202 | continue; |
203 | } | |
204 | ||
3a978377 TG |
205 | delta = clocksource_delta(wdnow, cs->wd_last, watchdog->mask); |
206 | wd_nsec = clocksource_cyc2ns(delta, watchdog->mult, | |
207 | watchdog->shift); | |
b5199515 | 208 | |
3a978377 TG |
209 | delta = clocksource_delta(csnow, cs->cs_last, cs->mask); |
210 | cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift); | |
0b046b21 JS |
211 | wdlast = cs->wd_last; /* save these in case we print them */ |
212 | cslast = cs->cs_last; | |
b5199515 TG |
213 | cs->cs_last = csnow; |
214 | cs->wd_last = wdnow; | |
215 | ||
9fb60336 TG |
216 | if (atomic_read(&watchdog_reset_pending)) |
217 | continue; | |
218 | ||
b5199515 | 219 | /* Check the deviation from the watchdog clocksource. */ |
79211c8e | 220 | if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) { |
45bbfe64 JP |
221 | pr_warn("timekeeping watchdog: Marking clocksource '%s' as unstable because the skew is too large:\n", |
222 | cs->name); | |
223 | pr_warn(" '%s' wd_now: %llx wd_last: %llx mask: %llx\n", | |
0b046b21 | 224 | watchdog->name, wdnow, wdlast, watchdog->mask); |
45bbfe64 | 225 | pr_warn(" '%s' cs_now: %llx cs_last: %llx mask: %llx\n", |
0b046b21 JS |
226 | cs->name, csnow, cslast, cs->mask); |
227 | __clocksource_unstable(cs); | |
8cf4e750 MS |
228 | continue; |
229 | } | |
230 | ||
231 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && | |
232 | (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
233 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
332962f2 | 234 | /* Mark it valid for high-res. */ |
8cf4e750 | 235 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
332962f2 TG |
236 | |
237 | /* | |
238 | * clocksource_done_booting() will sort it if | |
239 | * finished_booting is not set yet. | |
240 | */ | |
241 | if (!finished_booting) | |
242 | continue; | |
243 | ||
8cf4e750 | 244 | /* |
332962f2 TG |
245 | * If this is not the current clocksource let |
246 | * the watchdog thread reselect it. Due to the | |
247 | * change to high res this clocksource might | |
248 | * be preferred now. If it is the current | |
249 | * clocksource let the tick code know about | |
250 | * that change. | |
8cf4e750 | 251 | */ |
332962f2 TG |
252 | if (cs != curr_clocksource) { |
253 | cs->flags |= CLOCK_SOURCE_RESELECT; | |
254 | schedule_work(&watchdog_work); | |
255 | } else { | |
256 | tick_clock_notify(); | |
257 | } | |
5d8b34fd TG |
258 | } |
259 | } | |
260 | ||
9fb60336 TG |
261 | /* |
262 | * We only clear the watchdog_reset_pending, when we did a | |
263 | * full cycle through all clocksources. | |
264 | */ | |
265 | if (reset_pending) | |
266 | atomic_dec(&watchdog_reset_pending); | |
267 | ||
c55c87c8 MS |
268 | /* |
269 | * Cycle through CPUs to check if the CPUs stay synchronized | |
270 | * to each other. | |
271 | */ | |
272 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); | |
273 | if (next_cpu >= nr_cpu_ids) | |
274 | next_cpu = cpumask_first(cpu_online_mask); | |
275 | watchdog_timer.expires += WATCHDOG_INTERVAL; | |
276 | add_timer_on(&watchdog_timer, next_cpu); | |
fb63a0eb | 277 | out: |
5d8b34fd TG |
278 | spin_unlock(&watchdog_lock); |
279 | } | |
0f8e8ef7 | 280 | |
fb63a0eb MS |
281 | static inline void clocksource_start_watchdog(void) |
282 | { | |
283 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) | |
284 | return; | |
285 | init_timer(&watchdog_timer); | |
286 | watchdog_timer.function = clocksource_watchdog; | |
fb63a0eb MS |
287 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; |
288 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); | |
289 | watchdog_running = 1; | |
290 | } | |
291 | ||
292 | static inline void clocksource_stop_watchdog(void) | |
293 | { | |
294 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) | |
295 | return; | |
296 | del_timer(&watchdog_timer); | |
297 | watchdog_running = 0; | |
298 | } | |
299 | ||
0f8e8ef7 MS |
300 | static inline void clocksource_reset_watchdog(void) |
301 | { | |
302 | struct clocksource *cs; | |
303 | ||
304 | list_for_each_entry(cs, &watchdog_list, wd_list) | |
305 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
306 | } | |
307 | ||
b52f52a0 TG |
308 | static void clocksource_resume_watchdog(void) |
309 | { | |
9fb60336 | 310 | atomic_inc(&watchdog_reset_pending); |
b52f52a0 TG |
311 | } |
312 | ||
fb63a0eb | 313 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
5d8b34fd | 314 | { |
5d8b34fd TG |
315 | unsigned long flags; |
316 | ||
317 | spin_lock_irqsave(&watchdog_lock, flags); | |
318 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
fb63a0eb | 319 | /* cs is a clocksource to be watched. */ |
5d8b34fd | 320 | list_add(&cs->wd_list, &watchdog_list); |
fb63a0eb | 321 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
948ac6d7 | 322 | } else { |
fb63a0eb | 323 | /* cs is a watchdog. */ |
948ac6d7 | 324 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
5d8b34fd | 325 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
fb63a0eb | 326 | /* Pick the best watchdog. */ |
5d8b34fd | 327 | if (!watchdog || cs->rating > watchdog->rating) { |
5d8b34fd | 328 | watchdog = cs; |
5d8b34fd | 329 | /* Reset watchdog cycles */ |
0f8e8ef7 | 330 | clocksource_reset_watchdog(); |
5d8b34fd TG |
331 | } |
332 | } | |
fb63a0eb MS |
333 | /* Check if the watchdog timer needs to be started. */ |
334 | clocksource_start_watchdog(); | |
5d8b34fd TG |
335 | spin_unlock_irqrestore(&watchdog_lock, flags); |
336 | } | |
fb63a0eb MS |
337 | |
338 | static void clocksource_dequeue_watchdog(struct clocksource *cs) | |
339 | { | |
fb63a0eb MS |
340 | unsigned long flags; |
341 | ||
342 | spin_lock_irqsave(&watchdog_lock, flags); | |
a89c7edb TG |
343 | if (cs != watchdog) { |
344 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
345 | /* cs is a watched clocksource. */ | |
346 | list_del_init(&cs->wd_list); | |
347 | /* Check if the watchdog timer needs to be stopped. */ | |
348 | clocksource_stop_watchdog(); | |
fb63a0eb MS |
349 | } |
350 | } | |
fb63a0eb MS |
351 | spin_unlock_irqrestore(&watchdog_lock, flags); |
352 | } | |
353 | ||
332962f2 | 354 | static int __clocksource_watchdog_kthread(void) |
c55c87c8 MS |
355 | { |
356 | struct clocksource *cs, *tmp; | |
357 | unsigned long flags; | |
6ea41d25 | 358 | LIST_HEAD(unstable); |
332962f2 | 359 | int select = 0; |
c55c87c8 MS |
360 | |
361 | spin_lock_irqsave(&watchdog_lock, flags); | |
332962f2 | 362 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { |
c55c87c8 MS |
363 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
364 | list_del_init(&cs->wd_list); | |
6ea41d25 | 365 | list_add(&cs->wd_list, &unstable); |
332962f2 TG |
366 | select = 1; |
367 | } | |
368 | if (cs->flags & CLOCK_SOURCE_RESELECT) { | |
369 | cs->flags &= ~CLOCK_SOURCE_RESELECT; | |
370 | select = 1; | |
c55c87c8 | 371 | } |
332962f2 | 372 | } |
c55c87c8 MS |
373 | /* Check if the watchdog timer needs to be stopped. */ |
374 | clocksource_stop_watchdog(); | |
6ea41d25 TG |
375 | spin_unlock_irqrestore(&watchdog_lock, flags); |
376 | ||
377 | /* Needs to be done outside of watchdog lock */ | |
378 | list_for_each_entry_safe(cs, tmp, &unstable, wd_list) { | |
379 | list_del_init(&cs->wd_list); | |
d0981a1b | 380 | __clocksource_change_rating(cs, 0); |
6ea41d25 | 381 | } |
332962f2 TG |
382 | return select; |
383 | } | |
384 | ||
385 | static int clocksource_watchdog_kthread(void *data) | |
386 | { | |
387 | mutex_lock(&clocksource_mutex); | |
388 | if (__clocksource_watchdog_kthread()) | |
389 | clocksource_select(); | |
d0981a1b | 390 | mutex_unlock(&clocksource_mutex); |
01548f4d | 391 | return 0; |
c55c87c8 MS |
392 | } |
393 | ||
7eaeb343 TG |
394 | static bool clocksource_is_watchdog(struct clocksource *cs) |
395 | { | |
396 | return cs == watchdog; | |
397 | } | |
398 | ||
fb63a0eb MS |
399 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
400 | ||
401 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
5d8b34fd TG |
402 | { |
403 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
404 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
405 | } | |
b52f52a0 | 406 | |
fb63a0eb | 407 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
b52f52a0 | 408 | static inline void clocksource_resume_watchdog(void) { } |
332962f2 | 409 | static inline int __clocksource_watchdog_kthread(void) { return 0; } |
7eaeb343 | 410 | static bool clocksource_is_watchdog(struct clocksource *cs) { return false; } |
397bbf6d | 411 | void clocksource_mark_unstable(struct clocksource *cs) { } |
fb63a0eb MS |
412 | |
413 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ | |
5d8b34fd | 414 | |
c54a42b1 MD |
415 | /** |
416 | * clocksource_suspend - suspend the clocksource(s) | |
417 | */ | |
418 | void clocksource_suspend(void) | |
419 | { | |
420 | struct clocksource *cs; | |
421 | ||
422 | list_for_each_entry_reverse(cs, &clocksource_list, list) | |
423 | if (cs->suspend) | |
424 | cs->suspend(cs); | |
425 | } | |
426 | ||
b52f52a0 TG |
427 | /** |
428 | * clocksource_resume - resume the clocksource(s) | |
429 | */ | |
430 | void clocksource_resume(void) | |
431 | { | |
2e197586 | 432 | struct clocksource *cs; |
b52f52a0 | 433 | |
75c5158f | 434 | list_for_each_entry(cs, &clocksource_list, list) |
b52f52a0 | 435 | if (cs->resume) |
17622339 | 436 | cs->resume(cs); |
b52f52a0 TG |
437 | |
438 | clocksource_resume_watchdog(); | |
b52f52a0 TG |
439 | } |
440 | ||
7c3078b6 JW |
441 | /** |
442 | * clocksource_touch_watchdog - Update watchdog | |
443 | * | |
444 | * Update the watchdog after exception contexts such as kgdb so as not | |
7b7422a5 TG |
445 | * to incorrectly trip the watchdog. This might fail when the kernel |
446 | * was stopped in code which holds watchdog_lock. | |
7c3078b6 JW |
447 | */ |
448 | void clocksource_touch_watchdog(void) | |
449 | { | |
450 | clocksource_resume_watchdog(); | |
451 | } | |
452 | ||
d65670a7 JS |
453 | /** |
454 | * clocksource_max_adjustment- Returns max adjustment amount | |
455 | * @cs: Pointer to clocksource | |
456 | * | |
457 | */ | |
458 | static u32 clocksource_max_adjustment(struct clocksource *cs) | |
459 | { | |
460 | u64 ret; | |
461 | /* | |
88b28adf | 462 | * We won't try to correct for more than 11% adjustments (110,000 ppm), |
d65670a7 JS |
463 | */ |
464 | ret = (u64)cs->mult * 11; | |
465 | do_div(ret,100); | |
466 | return (u32)ret; | |
467 | } | |
468 | ||
98962465 | 469 | /** |
87d8b9eb SB |
470 | * clocks_calc_max_nsecs - Returns maximum nanoseconds that can be converted |
471 | * @mult: cycle to nanosecond multiplier | |
472 | * @shift: cycle to nanosecond divisor (power of two) | |
473 | * @maxadj: maximum adjustment value to mult (~11%) | |
474 | * @mask: bitmask for two's complement subtraction of non 64 bit counters | |
fb82fe2f JS |
475 | * @max_cyc: maximum cycle value before potential overflow (does not include |
476 | * any safety margin) | |
362fde04 | 477 | * |
8e56f33f JS |
478 | * NOTE: This function includes a safety margin of 50%, in other words, we |
479 | * return half the number of nanoseconds the hardware counter can technically | |
480 | * cover. This is done so that we can potentially detect problems caused by | |
481 | * delayed timers or bad hardware, which might result in time intervals that | |
571af55a | 482 | * are larger than what the math used can handle without overflows. |
98962465 | 483 | */ |
fb82fe2f | 484 | u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cyc) |
98962465 JH |
485 | { |
486 | u64 max_nsecs, max_cycles; | |
487 | ||
488 | /* | |
489 | * Calculate the maximum number of cycles that we can pass to the | |
6086e346 | 490 | * cyc2ns() function without overflowing a 64-bit result. |
98962465 | 491 | */ |
6086e346 JS |
492 | max_cycles = ULLONG_MAX; |
493 | do_div(max_cycles, mult+maxadj); | |
98962465 JH |
494 | |
495 | /* | |
496 | * The actual maximum number of cycles we can defer the clocksource is | |
87d8b9eb | 497 | * determined by the minimum of max_cycles and mask. |
d65670a7 JS |
498 | * Note: Here we subtract the maxadj to make sure we don't sleep for |
499 | * too long if there's a large negative adjustment. | |
98962465 | 500 | */ |
87d8b9eb SB |
501 | max_cycles = min(max_cycles, mask); |
502 | max_nsecs = clocksource_cyc2ns(max_cycles, mult - maxadj, shift); | |
503 | ||
fb82fe2f JS |
504 | /* return the max_cycles value as well if requested */ |
505 | if (max_cyc) | |
506 | *max_cyc = max_cycles; | |
507 | ||
362fde04 JS |
508 | /* Return 50% of the actual maximum, so we can detect bad values */ |
509 | max_nsecs >>= 1; | |
510 | ||
87d8b9eb SB |
511 | return max_nsecs; |
512 | } | |
513 | ||
514 | /** | |
fb82fe2f JS |
515 | * clocksource_update_max_deferment - Updates the clocksource max_idle_ns & max_cycles |
516 | * @cs: Pointer to clocksource to be updated | |
87d8b9eb SB |
517 | * |
518 | */ | |
fb82fe2f | 519 | static inline void clocksource_update_max_deferment(struct clocksource *cs) |
87d8b9eb | 520 | { |
fb82fe2f JS |
521 | cs->max_idle_ns = clocks_calc_max_nsecs(cs->mult, cs->shift, |
522 | cs->maxadj, cs->mask, | |
523 | &cs->max_cycles); | |
98962465 JH |
524 | } |
525 | ||
592913ec | 526 | #ifndef CONFIG_ARCH_USES_GETTIMEOFFSET |
734efb46 | 527 | |
f5a2e343 | 528 | static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur) |
5d33b883 TG |
529 | { |
530 | struct clocksource *cs; | |
531 | ||
532 | if (!finished_booting || list_empty(&clocksource_list)) | |
533 | return NULL; | |
534 | ||
535 | /* | |
536 | * We pick the clocksource with the highest rating. If oneshot | |
537 | * mode is active, we pick the highres valid clocksource with | |
538 | * the best rating. | |
539 | */ | |
540 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
541 | if (skipcur && cs == curr_clocksource) |
542 | continue; | |
5d33b883 TG |
543 | if (oneshot && !(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES)) |
544 | continue; | |
545 | return cs; | |
546 | } | |
547 | return NULL; | |
548 | } | |
549 | ||
f5a2e343 | 550 | static void __clocksource_select(bool skipcur) |
734efb46 | 551 | { |
5d33b883 | 552 | bool oneshot = tick_oneshot_mode_active(); |
f1b82746 | 553 | struct clocksource *best, *cs; |
5d8b34fd | 554 | |
5d33b883 | 555 | /* Find the best suitable clocksource */ |
f5a2e343 | 556 | best = clocksource_find_best(oneshot, skipcur); |
5d33b883 | 557 | if (!best) |
f1b82746 | 558 | return; |
5d33b883 | 559 | |
f1b82746 MS |
560 | /* Check for the override clocksource. */ |
561 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
562 | if (skipcur && cs == curr_clocksource) |
563 | continue; | |
f1b82746 MS |
564 | if (strcmp(cs->name, override_name) != 0) |
565 | continue; | |
566 | /* | |
567 | * Check to make sure we don't switch to a non-highres | |
568 | * capable clocksource if the tick code is in oneshot | |
569 | * mode (highres or nohz) | |
570 | */ | |
5d33b883 | 571 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && oneshot) { |
f1b82746 | 572 | /* Override clocksource cannot be used. */ |
45bbfe64 JP |
573 | pr_warn("Override clocksource %s is not HRT compatible - cannot switch while in HRT/NOHZ mode\n", |
574 | cs->name); | |
f1b82746 MS |
575 | override_name[0] = 0; |
576 | } else | |
577 | /* Override clocksource can be used. */ | |
578 | best = cs; | |
579 | break; | |
580 | } | |
ba919d1c TG |
581 | |
582 | if (curr_clocksource != best && !timekeeping_notify(best)) { | |
583 | pr_info("Switched to clocksource %s\n", best->name); | |
75c5158f | 584 | curr_clocksource = best; |
75c5158f | 585 | } |
f1b82746 | 586 | } |
734efb46 | 587 | |
f5a2e343 TG |
588 | /** |
589 | * clocksource_select - Select the best clocksource available | |
590 | * | |
591 | * Private function. Must hold clocksource_mutex when called. | |
592 | * | |
593 | * Select the clocksource with the best rating, or the clocksource, | |
594 | * which is selected by userspace override. | |
595 | */ | |
596 | static void clocksource_select(void) | |
597 | { | |
cfed432d | 598 | __clocksource_select(false); |
f5a2e343 TG |
599 | } |
600 | ||
7eaeb343 TG |
601 | static void clocksource_select_fallback(void) |
602 | { | |
cfed432d | 603 | __clocksource_select(true); |
7eaeb343 TG |
604 | } |
605 | ||
592913ec | 606 | #else /* !CONFIG_ARCH_USES_GETTIMEOFFSET */ |
54a6bc0b | 607 | static inline void clocksource_select(void) { } |
1eaff672 | 608 | static inline void clocksource_select_fallback(void) { } |
54a6bc0b TG |
609 | |
610 | #endif | |
611 | ||
75c5158f MS |
612 | /* |
613 | * clocksource_done_booting - Called near the end of core bootup | |
614 | * | |
615 | * Hack to avoid lots of clocksource churn at boot time. | |
616 | * We use fs_initcall because we want this to start before | |
617 | * device_initcall but after subsys_initcall. | |
618 | */ | |
619 | static int __init clocksource_done_booting(void) | |
620 | { | |
ad6759fb JS |
621 | mutex_lock(&clocksource_mutex); |
622 | curr_clocksource = clocksource_default_clock(); | |
75c5158f | 623 | finished_booting = 1; |
54a6bc0b TG |
624 | /* |
625 | * Run the watchdog first to eliminate unstable clock sources | |
626 | */ | |
332962f2 | 627 | __clocksource_watchdog_kthread(); |
75c5158f | 628 | clocksource_select(); |
e6c73305 | 629 | mutex_unlock(&clocksource_mutex); |
75c5158f MS |
630 | return 0; |
631 | } | |
632 | fs_initcall(clocksource_done_booting); | |
633 | ||
92c7e002 TG |
634 | /* |
635 | * Enqueue the clocksource sorted by rating | |
734efb46 | 636 | */ |
f1b82746 | 637 | static void clocksource_enqueue(struct clocksource *cs) |
734efb46 | 638 | { |
f1b82746 MS |
639 | struct list_head *entry = &clocksource_list; |
640 | struct clocksource *tmp; | |
92c7e002 | 641 | |
f1b82746 | 642 | list_for_each_entry(tmp, &clocksource_list, list) |
92c7e002 | 643 | /* Keep track of the place, where to insert */ |
f1b82746 MS |
644 | if (tmp->rating >= cs->rating) |
645 | entry = &tmp->list; | |
646 | list_add(&cs->list, entry); | |
734efb46 JS |
647 | } |
648 | ||
d7e81c26 | 649 | /** |
fba9e072 | 650 | * __clocksource_update_freq_scale - Used update clocksource with new freq |
b1b73d09 | 651 | * @cs: clocksource to be registered |
d7e81c26 JS |
652 | * @scale: Scale factor multiplied against freq to get clocksource hz |
653 | * @freq: clocksource frequency (cycles per second) divided by scale | |
654 | * | |
852db46d | 655 | * This should only be called from the clocksource->enable() method. |
d7e81c26 JS |
656 | * |
657 | * This *SHOULD NOT* be called directly! Please use the | |
fba9e072 JS |
658 | * __clocksource_update_freq_hz() or __clocksource_update_freq_khz() helper |
659 | * functions. | |
d7e81c26 | 660 | */ |
fba9e072 | 661 | void __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq) |
d7e81c26 | 662 | { |
c0e299b1 | 663 | u64 sec; |
f8935983 | 664 | |
d7e81c26 | 665 | /* |
f8935983 JS |
666 | * Default clocksources are *special* and self-define their mult/shift. |
667 | * But, you're not special, so you should specify a freq value. | |
d7e81c26 | 668 | */ |
f8935983 JS |
669 | if (freq) { |
670 | /* | |
671 | * Calc the maximum number of seconds which we can run before | |
672 | * wrapping around. For clocksources which have a mask > 32-bit | |
673 | * we need to limit the max sleep time to have a good | |
674 | * conversion precision. 10 minutes is still a reasonable | |
675 | * amount. That results in a shift value of 24 for a | |
676 | * clocksource with mask >= 40-bit and f >= 4GHz. That maps to | |
677 | * ~ 0.06ppm granularity for NTP. | |
678 | */ | |
679 | sec = cs->mask; | |
680 | do_div(sec, freq); | |
681 | do_div(sec, scale); | |
682 | if (!sec) | |
683 | sec = 1; | |
684 | else if (sec > 600 && cs->mask > UINT_MAX) | |
685 | sec = 600; | |
686 | ||
687 | clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, | |
688 | NSEC_PER_SEC / scale, sec * scale); | |
689 | } | |
d65670a7 | 690 | /* |
362fde04 JS |
691 | * Ensure clocksources that have large 'mult' values don't overflow |
692 | * when adjusted. | |
d65670a7 JS |
693 | */ |
694 | cs->maxadj = clocksource_max_adjustment(cs); | |
f8935983 JS |
695 | while (freq && ((cs->mult + cs->maxadj < cs->mult) |
696 | || (cs->mult - cs->maxadj > cs->mult))) { | |
d65670a7 JS |
697 | cs->mult >>= 1; |
698 | cs->shift--; | |
699 | cs->maxadj = clocksource_max_adjustment(cs); | |
700 | } | |
701 | ||
f8935983 JS |
702 | /* |
703 | * Only warn for *special* clocksources that self-define | |
704 | * their mult/shift values and don't specify a freq. | |
705 | */ | |
706 | WARN_ONCE(cs->mult + cs->maxadj < cs->mult, | |
707 | "timekeeping: Clocksource %s might overflow on 11%% adjustment\n", | |
708 | cs->name); | |
709 | ||
fb82fe2f | 710 | clocksource_update_max_deferment(cs); |
8cc8c525 | 711 | |
45bbfe64 JP |
712 | pr_info("%s: mask: 0x%llx max_cycles: 0x%llx, max_idle_ns: %lld ns\n", |
713 | cs->name, cs->mask, cs->max_cycles, cs->max_idle_ns); | |
852db46d | 714 | } |
fba9e072 | 715 | EXPORT_SYMBOL_GPL(__clocksource_update_freq_scale); |
852db46d JS |
716 | |
717 | /** | |
718 | * __clocksource_register_scale - Used to install new clocksources | |
b1b73d09 | 719 | * @cs: clocksource to be registered |
852db46d JS |
720 | * @scale: Scale factor multiplied against freq to get clocksource hz |
721 | * @freq: clocksource frequency (cycles per second) divided by scale | |
722 | * | |
723 | * Returns -EBUSY if registration fails, zero otherwise. | |
724 | * | |
725 | * This *SHOULD NOT* be called directly! Please use the | |
726 | * clocksource_register_hz() or clocksource_register_khz helper functions. | |
727 | */ | |
728 | int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) | |
729 | { | |
730 | ||
b595076a | 731 | /* Initialize mult/shift and max_idle_ns */ |
fba9e072 | 732 | __clocksource_update_freq_scale(cs, scale, freq); |
d7e81c26 | 733 | |
be278e98 | 734 | /* Add clocksource to the clocksource list */ |
d7e81c26 JS |
735 | mutex_lock(&clocksource_mutex); |
736 | clocksource_enqueue(cs); | |
d7e81c26 | 737 | clocksource_enqueue_watchdog(cs); |
e05b2efb | 738 | clocksource_select(); |
d7e81c26 JS |
739 | mutex_unlock(&clocksource_mutex); |
740 | return 0; | |
741 | } | |
742 | EXPORT_SYMBOL_GPL(__clocksource_register_scale); | |
743 | ||
d0981a1b TG |
744 | static void __clocksource_change_rating(struct clocksource *cs, int rating) |
745 | { | |
746 | list_del(&cs->list); | |
747 | cs->rating = rating; | |
748 | clocksource_enqueue(cs); | |
d0981a1b TG |
749 | } |
750 | ||
734efb46 | 751 | /** |
92c7e002 | 752 | * clocksource_change_rating - Change the rating of a registered clocksource |
b1b73d09 KK |
753 | * @cs: clocksource to be changed |
754 | * @rating: new rating | |
734efb46 | 755 | */ |
92c7e002 | 756 | void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb46 | 757 | { |
75c5158f | 758 | mutex_lock(&clocksource_mutex); |
d0981a1b | 759 | __clocksource_change_rating(cs, rating); |
332962f2 | 760 | clocksource_select(); |
75c5158f | 761 | mutex_unlock(&clocksource_mutex); |
734efb46 | 762 | } |
fb63a0eb | 763 | EXPORT_SYMBOL(clocksource_change_rating); |
734efb46 | 764 | |
7eaeb343 TG |
765 | /* |
766 | * Unbind clocksource @cs. Called with clocksource_mutex held | |
767 | */ | |
768 | static int clocksource_unbind(struct clocksource *cs) | |
769 | { | |
770 | /* | |
771 | * I really can't convince myself to support this on hardware | |
772 | * designed by lobotomized monkeys. | |
773 | */ | |
774 | if (clocksource_is_watchdog(cs)) | |
775 | return -EBUSY; | |
776 | ||
777 | if (cs == curr_clocksource) { | |
778 | /* Select and try to install a replacement clock source */ | |
779 | clocksource_select_fallback(); | |
780 | if (curr_clocksource == cs) | |
781 | return -EBUSY; | |
782 | } | |
783 | clocksource_dequeue_watchdog(cs); | |
784 | list_del_init(&cs->list); | |
785 | return 0; | |
786 | } | |
787 | ||
4713e22c TG |
788 | /** |
789 | * clocksource_unregister - remove a registered clocksource | |
b1b73d09 | 790 | * @cs: clocksource to be unregistered |
4713e22c | 791 | */ |
a89c7edb | 792 | int clocksource_unregister(struct clocksource *cs) |
4713e22c | 793 | { |
a89c7edb TG |
794 | int ret = 0; |
795 | ||
75c5158f | 796 | mutex_lock(&clocksource_mutex); |
a89c7edb TG |
797 | if (!list_empty(&cs->list)) |
798 | ret = clocksource_unbind(cs); | |
75c5158f | 799 | mutex_unlock(&clocksource_mutex); |
a89c7edb | 800 | return ret; |
4713e22c | 801 | } |
fb63a0eb | 802 | EXPORT_SYMBOL(clocksource_unregister); |
4713e22c | 803 | |
2b013700 | 804 | #ifdef CONFIG_SYSFS |
734efb46 JS |
805 | /** |
806 | * sysfs_show_current_clocksources - sysfs interface for current clocksource | |
807 | * @dev: unused | |
b1b73d09 | 808 | * @attr: unused |
734efb46 JS |
809 | * @buf: char buffer to be filled with clocksource list |
810 | * | |
811 | * Provides sysfs interface for listing current clocksource. | |
812 | */ | |
813 | static ssize_t | |
d369a5d8 KS |
814 | sysfs_show_current_clocksources(struct device *dev, |
815 | struct device_attribute *attr, char *buf) | |
734efb46 | 816 | { |
5e2cb101 | 817 | ssize_t count = 0; |
734efb46 | 818 | |
75c5158f | 819 | mutex_lock(&clocksource_mutex); |
5e2cb101 | 820 | count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); |
75c5158f | 821 | mutex_unlock(&clocksource_mutex); |
734efb46 | 822 | |
5e2cb101 | 823 | return count; |
734efb46 JS |
824 | } |
825 | ||
891292a7 | 826 | ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt) |
29b54078 TG |
827 | { |
828 | size_t ret = cnt; | |
829 | ||
830 | /* strings from sysfs write are not 0 terminated! */ | |
831 | if (!cnt || cnt >= CS_NAME_LEN) | |
832 | return -EINVAL; | |
833 | ||
834 | /* strip of \n: */ | |
835 | if (buf[cnt-1] == '\n') | |
836 | cnt--; | |
837 | if (cnt > 0) | |
838 | memcpy(dst, buf, cnt); | |
839 | dst[cnt] = 0; | |
840 | return ret; | |
841 | } | |
842 | ||
734efb46 JS |
843 | /** |
844 | * sysfs_override_clocksource - interface for manually overriding clocksource | |
845 | * @dev: unused | |
b1b73d09 | 846 | * @attr: unused |
734efb46 JS |
847 | * @buf: name of override clocksource |
848 | * @count: length of buffer | |
849 | * | |
850 | * Takes input from sysfs interface for manually overriding the default | |
b71a8eb0 | 851 | * clocksource selection. |
734efb46 | 852 | */ |
d369a5d8 KS |
853 | static ssize_t sysfs_override_clocksource(struct device *dev, |
854 | struct device_attribute *attr, | |
734efb46 JS |
855 | const char *buf, size_t count) |
856 | { | |
233bcb41 | 857 | ssize_t ret; |
734efb46 | 858 | |
75c5158f | 859 | mutex_lock(&clocksource_mutex); |
734efb46 | 860 | |
03e13cf5 | 861 | ret = sysfs_get_uname(buf, override_name, count); |
29b54078 TG |
862 | if (ret >= 0) |
863 | clocksource_select(); | |
734efb46 | 864 | |
75c5158f | 865 | mutex_unlock(&clocksource_mutex); |
734efb46 JS |
866 | |
867 | return ret; | |
868 | } | |
869 | ||
7eaeb343 TG |
870 | /** |
871 | * sysfs_unbind_current_clocksource - interface for manually unbinding clocksource | |
872 | * @dev: unused | |
873 | * @attr: unused | |
874 | * @buf: unused | |
875 | * @count: length of buffer | |
876 | * | |
877 | * Takes input from sysfs interface for manually unbinding a clocksource. | |
878 | */ | |
879 | static ssize_t sysfs_unbind_clocksource(struct device *dev, | |
880 | struct device_attribute *attr, | |
881 | const char *buf, size_t count) | |
882 | { | |
883 | struct clocksource *cs; | |
884 | char name[CS_NAME_LEN]; | |
233bcb41 | 885 | ssize_t ret; |
7eaeb343 | 886 | |
03e13cf5 | 887 | ret = sysfs_get_uname(buf, name, count); |
7eaeb343 TG |
888 | if (ret < 0) |
889 | return ret; | |
890 | ||
891 | ret = -ENODEV; | |
892 | mutex_lock(&clocksource_mutex); | |
893 | list_for_each_entry(cs, &clocksource_list, list) { | |
894 | if (strcmp(cs->name, name)) | |
895 | continue; | |
896 | ret = clocksource_unbind(cs); | |
897 | break; | |
898 | } | |
899 | mutex_unlock(&clocksource_mutex); | |
900 | ||
901 | return ret ? ret : count; | |
902 | } | |
903 | ||
734efb46 JS |
904 | /** |
905 | * sysfs_show_available_clocksources - sysfs interface for listing clocksource | |
906 | * @dev: unused | |
b1b73d09 | 907 | * @attr: unused |
734efb46 JS |
908 | * @buf: char buffer to be filled with clocksource list |
909 | * | |
910 | * Provides sysfs interface for listing registered clocksources | |
911 | */ | |
912 | static ssize_t | |
d369a5d8 KS |
913 | sysfs_show_available_clocksources(struct device *dev, |
914 | struct device_attribute *attr, | |
4a0b2b4d | 915 | char *buf) |
734efb46 | 916 | { |
2e197586 | 917 | struct clocksource *src; |
5e2cb101 | 918 | ssize_t count = 0; |
734efb46 | 919 | |
75c5158f | 920 | mutex_lock(&clocksource_mutex); |
2e197586 | 921 | list_for_each_entry(src, &clocksource_list, list) { |
cd6d95d8 TG |
922 | /* |
923 | * Don't show non-HRES clocksource if the tick code is | |
924 | * in one shot mode (highres=on or nohz=on) | |
925 | */ | |
926 | if (!tick_oneshot_mode_active() || | |
927 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) | |
3f68535a | 928 | count += snprintf(buf + count, |
5e2cb101 MX |
929 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), |
930 | "%s ", src->name); | |
734efb46 | 931 | } |
75c5158f | 932 | mutex_unlock(&clocksource_mutex); |
734efb46 | 933 | |
5e2cb101 MX |
934 | count += snprintf(buf + count, |
935 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); | |
734efb46 | 936 | |
5e2cb101 | 937 | return count; |
734efb46 JS |
938 | } |
939 | ||
940 | /* | |
941 | * Sysfs setup bits: | |
942 | */ | |
d369a5d8 | 943 | static DEVICE_ATTR(current_clocksource, 0644, sysfs_show_current_clocksources, |
f5f1a24a | 944 | sysfs_override_clocksource); |
734efb46 | 945 | |
7eaeb343 TG |
946 | static DEVICE_ATTR(unbind_clocksource, 0200, NULL, sysfs_unbind_clocksource); |
947 | ||
d369a5d8 | 948 | static DEVICE_ATTR(available_clocksource, 0444, |
f5f1a24a | 949 | sysfs_show_available_clocksources, NULL); |
734efb46 | 950 | |
d369a5d8 | 951 | static struct bus_type clocksource_subsys = { |
af5ca3f4 | 952 | .name = "clocksource", |
d369a5d8 | 953 | .dev_name = "clocksource", |
734efb46 JS |
954 | }; |
955 | ||
d369a5d8 | 956 | static struct device device_clocksource = { |
734efb46 | 957 | .id = 0, |
d369a5d8 | 958 | .bus = &clocksource_subsys, |
734efb46 JS |
959 | }; |
960 | ||
ad596171 | 961 | static int __init init_clocksource_sysfs(void) |
734efb46 | 962 | { |
d369a5d8 | 963 | int error = subsys_system_register(&clocksource_subsys, NULL); |
734efb46 JS |
964 | |
965 | if (!error) | |
d369a5d8 | 966 | error = device_register(&device_clocksource); |
734efb46 | 967 | if (!error) |
d369a5d8 | 968 | error = device_create_file( |
734efb46 | 969 | &device_clocksource, |
d369a5d8 | 970 | &dev_attr_current_clocksource); |
7eaeb343 TG |
971 | if (!error) |
972 | error = device_create_file(&device_clocksource, | |
973 | &dev_attr_unbind_clocksource); | |
734efb46 | 974 | if (!error) |
d369a5d8 | 975 | error = device_create_file( |
734efb46 | 976 | &device_clocksource, |
d369a5d8 | 977 | &dev_attr_available_clocksource); |
734efb46 JS |
978 | return error; |
979 | } | |
980 | ||
981 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 982 | #endif /* CONFIG_SYSFS */ |
734efb46 JS |
983 | |
984 | /** | |
985 | * boot_override_clocksource - boot clock override | |
986 | * @str: override name | |
987 | * | |
988 | * Takes a clocksource= boot argument and uses it | |
989 | * as the clocksource override name. | |
990 | */ | |
991 | static int __init boot_override_clocksource(char* str) | |
992 | { | |
75c5158f | 993 | mutex_lock(&clocksource_mutex); |
734efb46 JS |
994 | if (str) |
995 | strlcpy(override_name, str, sizeof(override_name)); | |
75c5158f | 996 | mutex_unlock(&clocksource_mutex); |
734efb46 JS |
997 | return 1; |
998 | } | |
999 | ||
1000 | __setup("clocksource=", boot_override_clocksource); | |
1001 | ||
1002 | /** | |
1003 | * boot_override_clock - Compatibility layer for deprecated boot option | |
1004 | * @str: override name | |
1005 | * | |
1006 | * DEPRECATED! Takes a clock= boot argument and uses it | |
1007 | * as the clocksource override name | |
1008 | */ | |
1009 | static int __init boot_override_clock(char* str) | |
1010 | { | |
5d0cf410 | 1011 | if (!strcmp(str, "pmtmr")) { |
45bbfe64 | 1012 | pr_warn("clock=pmtmr is deprecated - use clocksource=acpi_pm\n"); |
5d0cf410 JS |
1013 | return boot_override_clocksource("acpi_pm"); |
1014 | } | |
45bbfe64 | 1015 | pr_warn("clock= boot option is deprecated - use clocksource=xyz\n"); |
734efb46 JS |
1016 | return boot_override_clocksource(str); |
1017 | } | |
1018 | ||
1019 | __setup("clock=", boot_override_clock); |