Commit | Line | Data |
---|---|---|
734efb46 | 1 | /* |
2 | * linux/kernel/time/clocksource.c | |
3 | * | |
4 | * This file contains the functions which manage clocksource drivers. | |
5 | * | |
6 | * Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2 of the License, or | |
11 | * (at your option) any later version. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program; if not, write to the Free Software | |
20 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
21 | * | |
22 | * TODO WishList: | |
23 | * o Allow clocksource drivers to be unregistered | |
734efb46 | 24 | */ |
25 | ||
d369a5d8 | 26 | #include <linux/device.h> |
734efb46 | 27 | #include <linux/clocksource.h> |
734efb46 | 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 | 34 | #include "tick-internal.h" |
3a978377 | 35 | #include "timekeeping_internal.h" |
03e13cf5 | 36 | |
a038a353 PO |
37 | void timecounter_init(struct timecounter *tc, |
38 | const struct cyclecounter *cc, | |
39 | u64 start_tstamp) | |
40 | { | |
41 | tc->cc = cc; | |
42 | tc->cycle_last = cc->read(cc); | |
43 | tc->nsec = start_tstamp; | |
44 | } | |
3586e0a9 | 45 | EXPORT_SYMBOL_GPL(timecounter_init); |
a038a353 PO |
46 | |
47 | /** | |
48 | * timecounter_read_delta - get nanoseconds since last call of this function | |
49 | * @tc: Pointer to time counter | |
50 | * | |
51 | * When the underlying cycle counter runs over, this will be handled | |
52 | * correctly as long as it does not run over more than once between | |
53 | * calls. | |
54 | * | |
55 | * The first call to this function for a new time counter initializes | |
56 | * the time tracking and returns an undefined result. | |
57 | */ | |
58 | static u64 timecounter_read_delta(struct timecounter *tc) | |
59 | { | |
60 | cycle_t cycle_now, cycle_delta; | |
61 | u64 ns_offset; | |
62 | ||
63 | /* read cycle counter: */ | |
64 | cycle_now = tc->cc->read(tc->cc); | |
65 | ||
66 | /* calculate the delta since the last timecounter_read_delta(): */ | |
67 | cycle_delta = (cycle_now - tc->cycle_last) & tc->cc->mask; | |
68 | ||
69 | /* convert to nanoseconds: */ | |
70 | ns_offset = cyclecounter_cyc2ns(tc->cc, cycle_delta); | |
71 | ||
72 | /* update time stamp of timecounter_read_delta() call: */ | |
73 | tc->cycle_last = cycle_now; | |
74 | ||
75 | return ns_offset; | |
76 | } | |
77 | ||
78 | u64 timecounter_read(struct timecounter *tc) | |
79 | { | |
80 | u64 nsec; | |
81 | ||
82 | /* increment time by nanoseconds since last call */ | |
83 | nsec = timecounter_read_delta(tc); | |
84 | nsec += tc->nsec; | |
85 | tc->nsec = nsec; | |
86 | ||
87 | return nsec; | |
88 | } | |
3586e0a9 | 89 | EXPORT_SYMBOL_GPL(timecounter_read); |
a038a353 PO |
90 | |
91 | u64 timecounter_cyc2time(struct timecounter *tc, | |
92 | cycle_t cycle_tstamp) | |
93 | { | |
94 | u64 cycle_delta = (cycle_tstamp - tc->cycle_last) & tc->cc->mask; | |
95 | u64 nsec; | |
96 | ||
97 | /* | |
98 | * Instead of always treating cycle_tstamp as more recent | |
99 | * than tc->cycle_last, detect when it is too far in the | |
100 | * future and treat it as old time stamp instead. | |
101 | */ | |
102 | if (cycle_delta > tc->cc->mask / 2) { | |
103 | cycle_delta = (tc->cycle_last - cycle_tstamp) & tc->cc->mask; | |
104 | nsec = tc->nsec - cyclecounter_cyc2ns(tc->cc, cycle_delta); | |
105 | } else { | |
106 | nsec = cyclecounter_cyc2ns(tc->cc, cycle_delta) + tc->nsec; | |
107 | } | |
108 | ||
109 | return nsec; | |
110 | } | |
3586e0a9 | 111 | EXPORT_SYMBOL_GPL(timecounter_cyc2time); |
a038a353 | 112 | |
7d2f944a TG |
113 | /** |
114 | * clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks | |
115 | * @mult: pointer to mult variable | |
116 | * @shift: pointer to shift variable | |
117 | * @from: frequency to convert from | |
118 | * @to: frequency to convert to | |
5fdade95 | 119 | * @maxsec: guaranteed runtime conversion range in seconds |
7d2f944a TG |
120 | * |
121 | * The function evaluates the shift/mult pair for the scaled math | |
122 | * operations of clocksources and clockevents. | |
123 | * | |
124 | * @to and @from are frequency values in HZ. For clock sources @to is | |
125 | * NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock | |
126 | * event @to is the counter frequency and @from is NSEC_PER_SEC. | |
127 | * | |
5fdade95 | 128 | * The @maxsec conversion range argument controls the time frame in |
7d2f944a TG |
129 | * seconds which must be covered by the runtime conversion with the |
130 | * calculated mult and shift factors. This guarantees that no 64bit | |
131 | * overflow happens when the input value of the conversion is | |
132 | * multiplied with the calculated mult factor. Larger ranges may | |
133 | * reduce the conversion accuracy by chosing smaller mult and shift | |
134 | * factors. | |
135 | */ | |
136 | void | |
5fdade95 | 137 | clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 maxsec) |
7d2f944a TG |
138 | { |
139 | u64 tmp; | |
140 | u32 sft, sftacc= 32; | |
141 | ||
142 | /* | |
143 | * Calculate the shift factor which is limiting the conversion | |
144 | * range: | |
145 | */ | |
5fdade95 | 146 | tmp = ((u64)maxsec * from) >> 32; |
7d2f944a TG |
147 | while (tmp) { |
148 | tmp >>=1; | |
149 | sftacc--; | |
150 | } | |
151 | ||
152 | /* | |
153 | * Find the conversion shift/mult pair which has the best | |
154 | * accuracy and fits the maxsec conversion range: | |
155 | */ | |
156 | for (sft = 32; sft > 0; sft--) { | |
157 | tmp = (u64) to << sft; | |
b5776c4a | 158 | tmp += from / 2; |
7d2f944a TG |
159 | do_div(tmp, from); |
160 | if ((tmp >> sftacc) == 0) | |
161 | break; | |
162 | } | |
163 | *mult = tmp; | |
164 | *shift = sft; | |
165 | } | |
166 | ||
734efb46 | 167 | /*[Clocksource internal variables]--------- |
168 | * curr_clocksource: | |
f1b82746 | 169 | * currently selected clocksource. |
734efb46 | 170 | * clocksource_list: |
171 | * linked list with the registered clocksources | |
75c5158f MS |
172 | * clocksource_mutex: |
173 | * protects manipulations to curr_clocksource and the clocksource_list | |
734efb46 | 174 | * override_name: |
175 | * Name of the user-specified clocksource. | |
176 | */ | |
f1b82746 | 177 | static struct clocksource *curr_clocksource; |
734efb46 | 178 | static LIST_HEAD(clocksource_list); |
75c5158f | 179 | static DEFINE_MUTEX(clocksource_mutex); |
29b54078 | 180 | static char override_name[CS_NAME_LEN]; |
54a6bc0b | 181 | static int finished_booting; |
734efb46 | 182 | |
5d8b34fd | 183 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
f79e0258 | 184 | static void clocksource_watchdog_work(struct work_struct *work); |
332962f2 | 185 | static void clocksource_select(void); |
f79e0258 | 186 | |
5d8b34fd TG |
187 | static LIST_HEAD(watchdog_list); |
188 | static struct clocksource *watchdog; | |
189 | static struct timer_list watchdog_timer; | |
f79e0258 | 190 | static DECLARE_WORK(watchdog_work, clocksource_watchdog_work); |
5d8b34fd | 191 | static DEFINE_SPINLOCK(watchdog_lock); |
fb63a0eb | 192 | static int watchdog_running; |
9fb60336 | 193 | static atomic_t watchdog_reset_pending; |
b52f52a0 | 194 | |
01548f4d | 195 | static int clocksource_watchdog_kthread(void *data); |
d0981a1b | 196 | static void __clocksource_change_rating(struct clocksource *cs, int rating); |
c55c87c8 | 197 | |
5d8b34fd | 198 | /* |
35c35d1a | 199 | * Interval: 0.5sec Threshold: 0.0625s |
5d8b34fd TG |
200 | */ |
201 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
35c35d1a | 202 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) |
5d8b34fd | 203 | |
01548f4d MS |
204 | static void clocksource_watchdog_work(struct work_struct *work) |
205 | { | |
206 | /* | |
207 | * If kthread_run fails the next watchdog scan over the | |
208 | * watchdog_list will find the unstable clock again. | |
209 | */ | |
210 | kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog"); | |
211 | } | |
212 | ||
7285dd7f | 213 | static void __clocksource_unstable(struct clocksource *cs) |
5d8b34fd | 214 | { |
5d8b34fd | 215 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); |
c55c87c8 | 216 | cs->flags |= CLOCK_SOURCE_UNSTABLE; |
54a6bc0b TG |
217 | if (finished_booting) |
218 | schedule_work(&watchdog_work); | |
5d8b34fd TG |
219 | } |
220 | ||
7285dd7f TG |
221 | static void clocksource_unstable(struct clocksource *cs, int64_t delta) |
222 | { | |
223 | printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n", | |
224 | cs->name, delta); | |
225 | __clocksource_unstable(cs); | |
226 | } | |
227 | ||
228 | /** | |
229 | * clocksource_mark_unstable - mark clocksource unstable via watchdog | |
230 | * @cs: clocksource to be marked unstable | |
231 | * | |
232 | * This function is called instead of clocksource_change_rating from | |
233 | * cpu hotplug code to avoid a deadlock between the clocksource mutex | |
234 | * and the cpu hotplug mutex. It defers the update of the clocksource | |
235 | * to the watchdog thread. | |
236 | */ | |
237 | void clocksource_mark_unstable(struct clocksource *cs) | |
238 | { | |
239 | unsigned long flags; | |
240 | ||
241 | spin_lock_irqsave(&watchdog_lock, flags); | |
242 | if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) { | |
243 | if (list_empty(&cs->wd_list)) | |
244 | list_add(&cs->wd_list, &watchdog_list); | |
245 | __clocksource_unstable(cs); | |
246 | } | |
247 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
248 | } | |
249 | ||
5d8b34fd TG |
250 | static void clocksource_watchdog(unsigned long data) |
251 | { | |
c55c87c8 | 252 | struct clocksource *cs; |
3a978377 | 253 | cycle_t csnow, wdnow, delta; |
5d8b34fd | 254 | int64_t wd_nsec, cs_nsec; |
9fb60336 | 255 | int next_cpu, reset_pending; |
5d8b34fd TG |
256 | |
257 | spin_lock(&watchdog_lock); | |
fb63a0eb MS |
258 | if (!watchdog_running) |
259 | goto out; | |
5d8b34fd | 260 | |
9fb60336 TG |
261 | reset_pending = atomic_read(&watchdog_reset_pending); |
262 | ||
c55c87c8 MS |
263 | list_for_each_entry(cs, &watchdog_list, wd_list) { |
264 | ||
265 | /* Clocksource already marked unstable? */ | |
01548f4d | 266 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
54a6bc0b TG |
267 | if (finished_booting) |
268 | schedule_work(&watchdog_work); | |
c55c87c8 | 269 | continue; |
01548f4d | 270 | } |
c55c87c8 | 271 | |
b5199515 | 272 | local_irq_disable(); |
8e19608e | 273 | csnow = cs->read(cs); |
b5199515 TG |
274 | wdnow = watchdog->read(watchdog); |
275 | local_irq_enable(); | |
b52f52a0 | 276 | |
8cf4e750 | 277 | /* Clocksource initialized ? */ |
9fb60336 TG |
278 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) || |
279 | atomic_read(&watchdog_reset_pending)) { | |
8cf4e750 | 280 | cs->flags |= CLOCK_SOURCE_WATCHDOG; |
b5199515 TG |
281 | cs->wd_last = wdnow; |
282 | cs->cs_last = csnow; | |
b52f52a0 TG |
283 | continue; |
284 | } | |
285 | ||
3a978377 TG |
286 | delta = clocksource_delta(wdnow, cs->wd_last, watchdog->mask); |
287 | wd_nsec = clocksource_cyc2ns(delta, watchdog->mult, | |
288 | watchdog->shift); | |
b5199515 | 289 | |
3a978377 TG |
290 | delta = clocksource_delta(csnow, cs->cs_last, cs->mask); |
291 | cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift); | |
b5199515 TG |
292 | cs->cs_last = csnow; |
293 | cs->wd_last = wdnow; | |
294 | ||
9fb60336 TG |
295 | if (atomic_read(&watchdog_reset_pending)) |
296 | continue; | |
297 | ||
b5199515 | 298 | /* Check the deviation from the watchdog clocksource. */ |
9fb60336 | 299 | if ((abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD)) { |
8cf4e750 MS |
300 | clocksource_unstable(cs, cs_nsec - wd_nsec); |
301 | continue; | |
302 | } | |
303 | ||
304 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && | |
305 | (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
306 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
332962f2 | 307 | /* Mark it valid for high-res. */ |
8cf4e750 | 308 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
332962f2 TG |
309 | |
310 | /* | |
311 | * clocksource_done_booting() will sort it if | |
312 | * finished_booting is not set yet. | |
313 | */ | |
314 | if (!finished_booting) | |
315 | continue; | |
316 | ||
8cf4e750 | 317 | /* |
332962f2 TG |
318 | * If this is not the current clocksource let |
319 | * the watchdog thread reselect it. Due to the | |
320 | * change to high res this clocksource might | |
321 | * be preferred now. If it is the current | |
322 | * clocksource let the tick code know about | |
323 | * that change. | |
8cf4e750 | 324 | */ |
332962f2 TG |
325 | if (cs != curr_clocksource) { |
326 | cs->flags |= CLOCK_SOURCE_RESELECT; | |
327 | schedule_work(&watchdog_work); | |
328 | } else { | |
329 | tick_clock_notify(); | |
330 | } | |
5d8b34fd TG |
331 | } |
332 | } | |
333 | ||
9fb60336 TG |
334 | /* |
335 | * We only clear the watchdog_reset_pending, when we did a | |
336 | * full cycle through all clocksources. | |
337 | */ | |
338 | if (reset_pending) | |
339 | atomic_dec(&watchdog_reset_pending); | |
340 | ||
c55c87c8 MS |
341 | /* |
342 | * Cycle through CPUs to check if the CPUs stay synchronized | |
343 | * to each other. | |
344 | */ | |
345 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); | |
346 | if (next_cpu >= nr_cpu_ids) | |
347 | next_cpu = cpumask_first(cpu_online_mask); | |
348 | watchdog_timer.expires += WATCHDOG_INTERVAL; | |
349 | add_timer_on(&watchdog_timer, next_cpu); | |
fb63a0eb | 350 | out: |
5d8b34fd TG |
351 | spin_unlock(&watchdog_lock); |
352 | } | |
0f8e8ef7 | 353 | |
fb63a0eb MS |
354 | static inline void clocksource_start_watchdog(void) |
355 | { | |
356 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) | |
357 | return; | |
358 | init_timer(&watchdog_timer); | |
359 | watchdog_timer.function = clocksource_watchdog; | |
fb63a0eb MS |
360 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; |
361 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); | |
362 | watchdog_running = 1; | |
363 | } | |
364 | ||
365 | static inline void clocksource_stop_watchdog(void) | |
366 | { | |
367 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) | |
368 | return; | |
369 | del_timer(&watchdog_timer); | |
370 | watchdog_running = 0; | |
371 | } | |
372 | ||
0f8e8ef7 MS |
373 | static inline void clocksource_reset_watchdog(void) |
374 | { | |
375 | struct clocksource *cs; | |
376 | ||
377 | list_for_each_entry(cs, &watchdog_list, wd_list) | |
378 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
379 | } | |
380 | ||
b52f52a0 TG |
381 | static void clocksource_resume_watchdog(void) |
382 | { | |
9fb60336 | 383 | atomic_inc(&watchdog_reset_pending); |
b52f52a0 TG |
384 | } |
385 | ||
fb63a0eb | 386 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
5d8b34fd | 387 | { |
5d8b34fd TG |
388 | unsigned long flags; |
389 | ||
390 | spin_lock_irqsave(&watchdog_lock, flags); | |
391 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
fb63a0eb | 392 | /* cs is a clocksource to be watched. */ |
5d8b34fd | 393 | list_add(&cs->wd_list, &watchdog_list); |
fb63a0eb | 394 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
948ac6d7 | 395 | } else { |
fb63a0eb | 396 | /* cs is a watchdog. */ |
948ac6d7 | 397 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
5d8b34fd | 398 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
fb63a0eb | 399 | /* Pick the best watchdog. */ |
5d8b34fd | 400 | if (!watchdog || cs->rating > watchdog->rating) { |
5d8b34fd | 401 | watchdog = cs; |
5d8b34fd | 402 | /* Reset watchdog cycles */ |
0f8e8ef7 | 403 | clocksource_reset_watchdog(); |
5d8b34fd TG |
404 | } |
405 | } | |
fb63a0eb MS |
406 | /* Check if the watchdog timer needs to be started. */ |
407 | clocksource_start_watchdog(); | |
5d8b34fd TG |
408 | spin_unlock_irqrestore(&watchdog_lock, flags); |
409 | } | |
fb63a0eb MS |
410 | |
411 | static void clocksource_dequeue_watchdog(struct clocksource *cs) | |
412 | { | |
fb63a0eb MS |
413 | unsigned long flags; |
414 | ||
415 | spin_lock_irqsave(&watchdog_lock, flags); | |
a89c7edb TG |
416 | if (cs != watchdog) { |
417 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
418 | /* cs is a watched clocksource. */ | |
419 | list_del_init(&cs->wd_list); | |
420 | /* Check if the watchdog timer needs to be stopped. */ | |
421 | clocksource_stop_watchdog(); | |
fb63a0eb MS |
422 | } |
423 | } | |
fb63a0eb MS |
424 | spin_unlock_irqrestore(&watchdog_lock, flags); |
425 | } | |
426 | ||
332962f2 | 427 | static int __clocksource_watchdog_kthread(void) |
c55c87c8 MS |
428 | { |
429 | struct clocksource *cs, *tmp; | |
430 | unsigned long flags; | |
6ea41d25 | 431 | LIST_HEAD(unstable); |
332962f2 | 432 | int select = 0; |
c55c87c8 MS |
433 | |
434 | spin_lock_irqsave(&watchdog_lock, flags); | |
332962f2 | 435 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { |
c55c87c8 MS |
436 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
437 | list_del_init(&cs->wd_list); | |
6ea41d25 | 438 | list_add(&cs->wd_list, &unstable); |
332962f2 TG |
439 | select = 1; |
440 | } | |
441 | if (cs->flags & CLOCK_SOURCE_RESELECT) { | |
442 | cs->flags &= ~CLOCK_SOURCE_RESELECT; | |
443 | select = 1; | |
c55c87c8 | 444 | } |
332962f2 | 445 | } |
c55c87c8 MS |
446 | /* Check if the watchdog timer needs to be stopped. */ |
447 | clocksource_stop_watchdog(); | |
6ea41d25 TG |
448 | spin_unlock_irqrestore(&watchdog_lock, flags); |
449 | ||
450 | /* Needs to be done outside of watchdog lock */ | |
451 | list_for_each_entry_safe(cs, tmp, &unstable, wd_list) { | |
452 | list_del_init(&cs->wd_list); | |
d0981a1b | 453 | __clocksource_change_rating(cs, 0); |
6ea41d25 | 454 | } |
332962f2 TG |
455 | return select; |
456 | } | |
457 | ||
458 | static int clocksource_watchdog_kthread(void *data) | |
459 | { | |
460 | mutex_lock(&clocksource_mutex); | |
461 | if (__clocksource_watchdog_kthread()) | |
462 | clocksource_select(); | |
d0981a1b | 463 | mutex_unlock(&clocksource_mutex); |
01548f4d | 464 | return 0; |
c55c87c8 MS |
465 | } |
466 | ||
7eaeb343 TG |
467 | static bool clocksource_is_watchdog(struct clocksource *cs) |
468 | { | |
469 | return cs == watchdog; | |
470 | } | |
471 | ||
fb63a0eb MS |
472 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
473 | ||
474 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
5d8b34fd TG |
475 | { |
476 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
477 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
478 | } | |
b52f52a0 | 479 | |
fb63a0eb | 480 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
b52f52a0 | 481 | static inline void clocksource_resume_watchdog(void) { } |
332962f2 | 482 | static inline int __clocksource_watchdog_kthread(void) { return 0; } |
7eaeb343 | 483 | static bool clocksource_is_watchdog(struct clocksource *cs) { return false; } |
397bbf6d | 484 | void clocksource_mark_unstable(struct clocksource *cs) { } |
fb63a0eb MS |
485 | |
486 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ | |
5d8b34fd | 487 | |
c54a42b1 MD |
488 | /** |
489 | * clocksource_suspend - suspend the clocksource(s) | |
490 | */ | |
491 | void clocksource_suspend(void) | |
492 | { | |
493 | struct clocksource *cs; | |
494 | ||
495 | list_for_each_entry_reverse(cs, &clocksource_list, list) | |
496 | if (cs->suspend) | |
497 | cs->suspend(cs); | |
498 | } | |
499 | ||
b52f52a0 TG |
500 | /** |
501 | * clocksource_resume - resume the clocksource(s) | |
502 | */ | |
503 | void clocksource_resume(void) | |
504 | { | |
2e197586 | 505 | struct clocksource *cs; |
b52f52a0 | 506 | |
75c5158f | 507 | list_for_each_entry(cs, &clocksource_list, list) |
b52f52a0 | 508 | if (cs->resume) |
17622339 | 509 | cs->resume(cs); |
b52f52a0 TG |
510 | |
511 | clocksource_resume_watchdog(); | |
b52f52a0 TG |
512 | } |
513 | ||
7c3078b6 JW |
514 | /** |
515 | * clocksource_touch_watchdog - Update watchdog | |
516 | * | |
517 | * Update the watchdog after exception contexts such as kgdb so as not | |
7b7422a5 TG |
518 | * to incorrectly trip the watchdog. This might fail when the kernel |
519 | * was stopped in code which holds watchdog_lock. | |
7c3078b6 JW |
520 | */ |
521 | void clocksource_touch_watchdog(void) | |
522 | { | |
523 | clocksource_resume_watchdog(); | |
524 | } | |
525 | ||
d65670a7 JS |
526 | /** |
527 | * clocksource_max_adjustment- Returns max adjustment amount | |
528 | * @cs: Pointer to clocksource | |
529 | * | |
530 | */ | |
531 | static u32 clocksource_max_adjustment(struct clocksource *cs) | |
532 | { | |
533 | u64 ret; | |
534 | /* | |
88b28adf | 535 | * We won't try to correct for more than 11% adjustments (110,000 ppm), |
d65670a7 JS |
536 | */ |
537 | ret = (u64)cs->mult * 11; | |
538 | do_div(ret,100); | |
539 | return (u32)ret; | |
540 | } | |
541 | ||
98962465 | 542 | /** |
87d8b9eb SB |
543 | * clocks_calc_max_nsecs - Returns maximum nanoseconds that can be converted |
544 | * @mult: cycle to nanosecond multiplier | |
545 | * @shift: cycle to nanosecond divisor (power of two) | |
546 | * @maxadj: maximum adjustment value to mult (~11%) | |
547 | * @mask: bitmask for two's complement subtraction of non 64 bit counters | |
98962465 | 548 | */ |
87d8b9eb | 549 | u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask) |
98962465 JH |
550 | { |
551 | u64 max_nsecs, max_cycles; | |
552 | ||
553 | /* | |
554 | * Calculate the maximum number of cycles that we can pass to the | |
555 | * cyc2ns function without overflowing a 64-bit signed result. The | |
87d8b9eb | 556 | * maximum number of cycles is equal to ULLONG_MAX/(mult+maxadj) |
d65670a7 | 557 | * which is equivalent to the below. |
87d8b9eb SB |
558 | * max_cycles < (2^63)/(mult + maxadj) |
559 | * max_cycles < 2^(log2((2^63)/(mult + maxadj))) | |
560 | * max_cycles < 2^(log2(2^63) - log2(mult + maxadj)) | |
561 | * max_cycles < 2^(63 - log2(mult + maxadj)) | |
562 | * max_cycles < 1 << (63 - log2(mult + maxadj)) | |
98962465 JH |
563 | * Please note that we add 1 to the result of the log2 to account for |
564 | * any rounding errors, ensure the above inequality is satisfied and | |
565 | * no overflow will occur. | |
566 | */ | |
87d8b9eb | 567 | max_cycles = 1ULL << (63 - (ilog2(mult + maxadj) + 1)); |
98962465 JH |
568 | |
569 | /* | |
570 | * The actual maximum number of cycles we can defer the clocksource is | |
87d8b9eb | 571 | * determined by the minimum of max_cycles and mask. |
d65670a7 JS |
572 | * Note: Here we subtract the maxadj to make sure we don't sleep for |
573 | * too long if there's a large negative adjustment. | |
98962465 | 574 | */ |
87d8b9eb SB |
575 | max_cycles = min(max_cycles, mask); |
576 | max_nsecs = clocksource_cyc2ns(max_cycles, mult - maxadj, shift); | |
577 | ||
578 | return max_nsecs; | |
579 | } | |
580 | ||
581 | /** | |
582 | * clocksource_max_deferment - Returns max time the clocksource can be deferred | |
583 | * @cs: Pointer to clocksource | |
584 | * | |
585 | */ | |
586 | static u64 clocksource_max_deferment(struct clocksource *cs) | |
587 | { | |
588 | u64 max_nsecs; | |
98962465 | 589 | |
87d8b9eb SB |
590 | max_nsecs = clocks_calc_max_nsecs(cs->mult, cs->shift, cs->maxadj, |
591 | cs->mask); | |
98962465 JH |
592 | /* |
593 | * To ensure that the clocksource does not wrap whilst we are idle, | |
594 | * limit the time the clocksource can be deferred by 12.5%. Please | |
595 | * note a margin of 12.5% is used because this can be computed with | |
596 | * a shift, versus say 10% which would require division. | |
597 | */ | |
b1f91966 | 598 | return max_nsecs - (max_nsecs >> 3); |
98962465 JH |
599 | } |
600 | ||
592913ec | 601 | #ifndef CONFIG_ARCH_USES_GETTIMEOFFSET |
734efb46 | 602 | |
f5a2e343 | 603 | static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur) |
5d33b883 TG |
604 | { |
605 | struct clocksource *cs; | |
606 | ||
607 | if (!finished_booting || list_empty(&clocksource_list)) | |
608 | return NULL; | |
609 | ||
610 | /* | |
611 | * We pick the clocksource with the highest rating. If oneshot | |
612 | * mode is active, we pick the highres valid clocksource with | |
613 | * the best rating. | |
614 | */ | |
615 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
616 | if (skipcur && cs == curr_clocksource) |
617 | continue; | |
5d33b883 TG |
618 | if (oneshot && !(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES)) |
619 | continue; | |
620 | return cs; | |
621 | } | |
622 | return NULL; | |
623 | } | |
624 | ||
f5a2e343 | 625 | static void __clocksource_select(bool skipcur) |
734efb46 | 626 | { |
5d33b883 | 627 | bool oneshot = tick_oneshot_mode_active(); |
f1b82746 | 628 | struct clocksource *best, *cs; |
5d8b34fd | 629 | |
5d33b883 | 630 | /* Find the best suitable clocksource */ |
f5a2e343 | 631 | best = clocksource_find_best(oneshot, skipcur); |
5d33b883 | 632 | if (!best) |
f1b82746 | 633 | return; |
5d33b883 | 634 | |
f1b82746 MS |
635 | /* Check for the override clocksource. */ |
636 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
637 | if (skipcur && cs == curr_clocksource) |
638 | continue; | |
f1b82746 MS |
639 | if (strcmp(cs->name, override_name) != 0) |
640 | continue; | |
641 | /* | |
642 | * Check to make sure we don't switch to a non-highres | |
643 | * capable clocksource if the tick code is in oneshot | |
644 | * mode (highres or nohz) | |
645 | */ | |
5d33b883 | 646 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && oneshot) { |
f1b82746 MS |
647 | /* Override clocksource cannot be used. */ |
648 | printk(KERN_WARNING "Override clocksource %s is not " | |
649 | "HRT compatible. Cannot switch while in " | |
650 | "HRT/NOHZ mode\n", cs->name); | |
651 | override_name[0] = 0; | |
652 | } else | |
653 | /* Override clocksource can be used. */ | |
654 | best = cs; | |
655 | break; | |
656 | } | |
ba919d1c TG |
657 | |
658 | if (curr_clocksource != best && !timekeeping_notify(best)) { | |
659 | pr_info("Switched to clocksource %s\n", best->name); | |
75c5158f | 660 | curr_clocksource = best; |
75c5158f | 661 | } |
f1b82746 | 662 | } |
734efb46 | 663 | |
f5a2e343 TG |
664 | /** |
665 | * clocksource_select - Select the best clocksource available | |
666 | * | |
667 | * Private function. Must hold clocksource_mutex when called. | |
668 | * | |
669 | * Select the clocksource with the best rating, or the clocksource, | |
670 | * which is selected by userspace override. | |
671 | */ | |
672 | static void clocksource_select(void) | |
673 | { | |
674 | return __clocksource_select(false); | |
675 | } | |
676 | ||
7eaeb343 TG |
677 | static void clocksource_select_fallback(void) |
678 | { | |
679 | return __clocksource_select(true); | |
680 | } | |
681 | ||
592913ec | 682 | #else /* !CONFIG_ARCH_USES_GETTIMEOFFSET */ |
54a6bc0b TG |
683 | |
684 | static inline void clocksource_select(void) { } | |
1eaff672 | 685 | static inline void clocksource_select_fallback(void) { } |
54a6bc0b TG |
686 | |
687 | #endif | |
688 | ||
75c5158f MS |
689 | /* |
690 | * clocksource_done_booting - Called near the end of core bootup | |
691 | * | |
692 | * Hack to avoid lots of clocksource churn at boot time. | |
693 | * We use fs_initcall because we want this to start before | |
694 | * device_initcall but after subsys_initcall. | |
695 | */ | |
696 | static int __init clocksource_done_booting(void) | |
697 | { | |
ad6759fb | 698 | mutex_lock(&clocksource_mutex); |
699 | curr_clocksource = clocksource_default_clock(); | |
75c5158f | 700 | finished_booting = 1; |
54a6bc0b TG |
701 | /* |
702 | * Run the watchdog first to eliminate unstable clock sources | |
703 | */ | |
332962f2 | 704 | __clocksource_watchdog_kthread(); |
75c5158f | 705 | clocksource_select(); |
e6c73305 | 706 | mutex_unlock(&clocksource_mutex); |
75c5158f MS |
707 | return 0; |
708 | } | |
709 | fs_initcall(clocksource_done_booting); | |
710 | ||
92c7e002 TG |
711 | /* |
712 | * Enqueue the clocksource sorted by rating | |
734efb46 | 713 | */ |
f1b82746 | 714 | static void clocksource_enqueue(struct clocksource *cs) |
734efb46 | 715 | { |
f1b82746 MS |
716 | struct list_head *entry = &clocksource_list; |
717 | struct clocksource *tmp; | |
92c7e002 | 718 | |
f1b82746 | 719 | list_for_each_entry(tmp, &clocksource_list, list) |
92c7e002 | 720 | /* Keep track of the place, where to insert */ |
f1b82746 MS |
721 | if (tmp->rating >= cs->rating) |
722 | entry = &tmp->list; | |
723 | list_add(&cs->list, entry); | |
734efb46 | 724 | } |
725 | ||
d7e81c26 | 726 | /** |
852db46d | 727 | * __clocksource_updatefreq_scale - Used update clocksource with new freq |
b1b73d09 | 728 | * @cs: clocksource to be registered |
d7e81c26 JS |
729 | * @scale: Scale factor multiplied against freq to get clocksource hz |
730 | * @freq: clocksource frequency (cycles per second) divided by scale | |
731 | * | |
852db46d | 732 | * This should only be called from the clocksource->enable() method. |
d7e81c26 JS |
733 | * |
734 | * This *SHOULD NOT* be called directly! Please use the | |
852db46d | 735 | * clocksource_updatefreq_hz() or clocksource_updatefreq_khz helper functions. |
d7e81c26 | 736 | */ |
852db46d | 737 | void __clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq) |
d7e81c26 | 738 | { |
c0e299b1 | 739 | u64 sec; |
d7e81c26 | 740 | /* |
724ed53e TG |
741 | * Calc the maximum number of seconds which we can run before |
742 | * wrapping around. For clocksources which have a mask > 32bit | |
743 | * we need to limit the max sleep time to have a good | |
744 | * conversion precision. 10 minutes is still a reasonable | |
745 | * amount. That results in a shift value of 24 for a | |
746 | * clocksource with mask >= 40bit and f >= 4GHz. That maps to | |
747 | * ~ 0.06ppm granularity for NTP. We apply the same 12.5% | |
748 | * margin as we do in clocksource_max_deferment() | |
d7e81c26 | 749 | */ |
b1f91966 | 750 | sec = (cs->mask - (cs->mask >> 3)); |
724ed53e TG |
751 | do_div(sec, freq); |
752 | do_div(sec, scale); | |
753 | if (!sec) | |
754 | sec = 1; | |
755 | else if (sec > 600 && cs->mask > UINT_MAX) | |
756 | sec = 600; | |
757 | ||
d7e81c26 | 758 | clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, |
724ed53e | 759 | NSEC_PER_SEC / scale, sec * scale); |
d65670a7 JS |
760 | |
761 | /* | |
762 | * for clocksources that have large mults, to avoid overflow. | |
763 | * Since mult may be adjusted by ntp, add an safety extra margin | |
764 | * | |
765 | */ | |
766 | cs->maxadj = clocksource_max_adjustment(cs); | |
767 | while ((cs->mult + cs->maxadj < cs->mult) | |
768 | || (cs->mult - cs->maxadj > cs->mult)) { | |
769 | cs->mult >>= 1; | |
770 | cs->shift--; | |
771 | cs->maxadj = clocksource_max_adjustment(cs); | |
772 | } | |
773 | ||
d7e81c26 | 774 | cs->max_idle_ns = clocksource_max_deferment(cs); |
852db46d JS |
775 | } |
776 | EXPORT_SYMBOL_GPL(__clocksource_updatefreq_scale); | |
777 | ||
778 | /** | |
779 | * __clocksource_register_scale - Used to install new clocksources | |
b1b73d09 | 780 | * @cs: clocksource to be registered |
852db46d JS |
781 | * @scale: Scale factor multiplied against freq to get clocksource hz |
782 | * @freq: clocksource frequency (cycles per second) divided by scale | |
783 | * | |
784 | * Returns -EBUSY if registration fails, zero otherwise. | |
785 | * | |
786 | * This *SHOULD NOT* be called directly! Please use the | |
787 | * clocksource_register_hz() or clocksource_register_khz helper functions. | |
788 | */ | |
789 | int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) | |
790 | { | |
791 | ||
b595076a | 792 | /* Initialize mult/shift and max_idle_ns */ |
852db46d | 793 | __clocksource_updatefreq_scale(cs, scale, freq); |
d7e81c26 | 794 | |
852db46d | 795 | /* Add clocksource to the clcoksource list */ |
d7e81c26 JS |
796 | mutex_lock(&clocksource_mutex); |
797 | clocksource_enqueue(cs); | |
d7e81c26 | 798 | clocksource_enqueue_watchdog(cs); |
e05b2efb | 799 | clocksource_select(); |
d7e81c26 JS |
800 | mutex_unlock(&clocksource_mutex); |
801 | return 0; | |
802 | } | |
803 | EXPORT_SYMBOL_GPL(__clocksource_register_scale); | |
804 | ||
805 | ||
734efb46 | 806 | /** |
a2752549 | 807 | * clocksource_register - Used to install new clocksources |
b1b73d09 | 808 | * @cs: clocksource to be registered |
734efb46 | 809 | * |
810 | * Returns -EBUSY if registration fails, zero otherwise. | |
811 | */ | |
f1b82746 | 812 | int clocksource_register(struct clocksource *cs) |
734efb46 | 813 | { |
d65670a7 JS |
814 | /* calculate max adjustment for given mult/shift */ |
815 | cs->maxadj = clocksource_max_adjustment(cs); | |
816 | WARN_ONCE(cs->mult + cs->maxadj < cs->mult, | |
817 | "Clocksource %s might overflow on 11%% adjustment\n", | |
818 | cs->name); | |
819 | ||
98962465 JH |
820 | /* calculate max idle time permitted for this clocksource */ |
821 | cs->max_idle_ns = clocksource_max_deferment(cs); | |
822 | ||
75c5158f | 823 | mutex_lock(&clocksource_mutex); |
f1b82746 | 824 | clocksource_enqueue(cs); |
fb63a0eb | 825 | clocksource_enqueue_watchdog(cs); |
e05b2efb | 826 | clocksource_select(); |
75c5158f | 827 | mutex_unlock(&clocksource_mutex); |
f1b82746 | 828 | return 0; |
734efb46 | 829 | } |
a2752549 | 830 | EXPORT_SYMBOL(clocksource_register); |
734efb46 | 831 | |
d0981a1b TG |
832 | static void __clocksource_change_rating(struct clocksource *cs, int rating) |
833 | { | |
834 | list_del(&cs->list); | |
835 | cs->rating = rating; | |
836 | clocksource_enqueue(cs); | |
d0981a1b TG |
837 | } |
838 | ||
734efb46 | 839 | /** |
92c7e002 | 840 | * clocksource_change_rating - Change the rating of a registered clocksource |
b1b73d09 KK |
841 | * @cs: clocksource to be changed |
842 | * @rating: new rating | |
734efb46 | 843 | */ |
92c7e002 | 844 | void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb46 | 845 | { |
75c5158f | 846 | mutex_lock(&clocksource_mutex); |
d0981a1b | 847 | __clocksource_change_rating(cs, rating); |
332962f2 | 848 | clocksource_select(); |
75c5158f | 849 | mutex_unlock(&clocksource_mutex); |
734efb46 | 850 | } |
fb63a0eb | 851 | EXPORT_SYMBOL(clocksource_change_rating); |
734efb46 | 852 | |
7eaeb343 TG |
853 | /* |
854 | * Unbind clocksource @cs. Called with clocksource_mutex held | |
855 | */ | |
856 | static int clocksource_unbind(struct clocksource *cs) | |
857 | { | |
858 | /* | |
859 | * I really can't convince myself to support this on hardware | |
860 | * designed by lobotomized monkeys. | |
861 | */ | |
862 | if (clocksource_is_watchdog(cs)) | |
863 | return -EBUSY; | |
864 | ||
865 | if (cs == curr_clocksource) { | |
866 | /* Select and try to install a replacement clock source */ | |
867 | clocksource_select_fallback(); | |
868 | if (curr_clocksource == cs) | |
869 | return -EBUSY; | |
870 | } | |
871 | clocksource_dequeue_watchdog(cs); | |
872 | list_del_init(&cs->list); | |
873 | return 0; | |
874 | } | |
875 | ||
4713e22c TG |
876 | /** |
877 | * clocksource_unregister - remove a registered clocksource | |
b1b73d09 | 878 | * @cs: clocksource to be unregistered |
4713e22c | 879 | */ |
a89c7edb | 880 | int clocksource_unregister(struct clocksource *cs) |
4713e22c | 881 | { |
a89c7edb TG |
882 | int ret = 0; |
883 | ||
75c5158f | 884 | mutex_lock(&clocksource_mutex); |
a89c7edb TG |
885 | if (!list_empty(&cs->list)) |
886 | ret = clocksource_unbind(cs); | |
75c5158f | 887 | mutex_unlock(&clocksource_mutex); |
a89c7edb | 888 | return ret; |
4713e22c | 889 | } |
fb63a0eb | 890 | EXPORT_SYMBOL(clocksource_unregister); |
4713e22c | 891 | |
2b013700 | 892 | #ifdef CONFIG_SYSFS |
734efb46 | 893 | /** |
894 | * sysfs_show_current_clocksources - sysfs interface for current clocksource | |
895 | * @dev: unused | |
b1b73d09 | 896 | * @attr: unused |
734efb46 | 897 | * @buf: char buffer to be filled with clocksource list |
898 | * | |
899 | * Provides sysfs interface for listing current clocksource. | |
900 | */ | |
901 | static ssize_t | |
d369a5d8 KS |
902 | sysfs_show_current_clocksources(struct device *dev, |
903 | struct device_attribute *attr, char *buf) | |
734efb46 | 904 | { |
5e2cb101 | 905 | ssize_t count = 0; |
734efb46 | 906 | |
75c5158f | 907 | mutex_lock(&clocksource_mutex); |
5e2cb101 | 908 | count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); |
75c5158f | 909 | mutex_unlock(&clocksource_mutex); |
734efb46 | 910 | |
5e2cb101 | 911 | return count; |
734efb46 | 912 | } |
913 | ||
891292a7 | 914 | ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt) |
29b54078 TG |
915 | { |
916 | size_t ret = cnt; | |
917 | ||
918 | /* strings from sysfs write are not 0 terminated! */ | |
919 | if (!cnt || cnt >= CS_NAME_LEN) | |
920 | return -EINVAL; | |
921 | ||
922 | /* strip of \n: */ | |
923 | if (buf[cnt-1] == '\n') | |
924 | cnt--; | |
925 | if (cnt > 0) | |
926 | memcpy(dst, buf, cnt); | |
927 | dst[cnt] = 0; | |
928 | return ret; | |
929 | } | |
930 | ||
734efb46 | 931 | /** |
932 | * sysfs_override_clocksource - interface for manually overriding clocksource | |
933 | * @dev: unused | |
b1b73d09 | 934 | * @attr: unused |
734efb46 | 935 | * @buf: name of override clocksource |
936 | * @count: length of buffer | |
937 | * | |
938 | * Takes input from sysfs interface for manually overriding the default | |
b71a8eb0 | 939 | * clocksource selection. |
734efb46 | 940 | */ |
d369a5d8 KS |
941 | static ssize_t sysfs_override_clocksource(struct device *dev, |
942 | struct device_attribute *attr, | |
734efb46 | 943 | const char *buf, size_t count) |
944 | { | |
233bcb41 | 945 | ssize_t ret; |
734efb46 | 946 | |
75c5158f | 947 | mutex_lock(&clocksource_mutex); |
734efb46 | 948 | |
03e13cf5 | 949 | ret = sysfs_get_uname(buf, override_name, count); |
29b54078 TG |
950 | if (ret >= 0) |
951 | clocksource_select(); | |
734efb46 | 952 | |
75c5158f | 953 | mutex_unlock(&clocksource_mutex); |
734efb46 | 954 | |
955 | return ret; | |
956 | } | |
957 | ||
7eaeb343 TG |
958 | /** |
959 | * sysfs_unbind_current_clocksource - interface for manually unbinding clocksource | |
960 | * @dev: unused | |
961 | * @attr: unused | |
962 | * @buf: unused | |
963 | * @count: length of buffer | |
964 | * | |
965 | * Takes input from sysfs interface for manually unbinding a clocksource. | |
966 | */ | |
967 | static ssize_t sysfs_unbind_clocksource(struct device *dev, | |
968 | struct device_attribute *attr, | |
969 | const char *buf, size_t count) | |
970 | { | |
971 | struct clocksource *cs; | |
972 | char name[CS_NAME_LEN]; | |
233bcb41 | 973 | ssize_t ret; |
7eaeb343 | 974 | |
03e13cf5 | 975 | ret = sysfs_get_uname(buf, name, count); |
7eaeb343 TG |
976 | if (ret < 0) |
977 | return ret; | |
978 | ||
979 | ret = -ENODEV; | |
980 | mutex_lock(&clocksource_mutex); | |
981 | list_for_each_entry(cs, &clocksource_list, list) { | |
982 | if (strcmp(cs->name, name)) | |
983 | continue; | |
984 | ret = clocksource_unbind(cs); | |
985 | break; | |
986 | } | |
987 | mutex_unlock(&clocksource_mutex); | |
988 | ||
989 | return ret ? ret : count; | |
990 | } | |
991 | ||
734efb46 | 992 | /** |
993 | * sysfs_show_available_clocksources - sysfs interface for listing clocksource | |
994 | * @dev: unused | |
b1b73d09 | 995 | * @attr: unused |
734efb46 | 996 | * @buf: char buffer to be filled with clocksource list |
997 | * | |
998 | * Provides sysfs interface for listing registered clocksources | |
999 | */ | |
1000 | static ssize_t | |
d369a5d8 KS |
1001 | sysfs_show_available_clocksources(struct device *dev, |
1002 | struct device_attribute *attr, | |
4a0b2b4d | 1003 | char *buf) |
734efb46 | 1004 | { |
2e197586 | 1005 | struct clocksource *src; |
5e2cb101 | 1006 | ssize_t count = 0; |
734efb46 | 1007 | |
75c5158f | 1008 | mutex_lock(&clocksource_mutex); |
2e197586 | 1009 | list_for_each_entry(src, &clocksource_list, list) { |
cd6d95d8 TG |
1010 | /* |
1011 | * Don't show non-HRES clocksource if the tick code is | |
1012 | * in one shot mode (highres=on or nohz=on) | |
1013 | */ | |
1014 | if (!tick_oneshot_mode_active() || | |
1015 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) | |
3f68535a | 1016 | count += snprintf(buf + count, |
5e2cb101 MX |
1017 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), |
1018 | "%s ", src->name); | |
734efb46 | 1019 | } |
75c5158f | 1020 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1021 | |
5e2cb101 MX |
1022 | count += snprintf(buf + count, |
1023 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); | |
734efb46 | 1024 | |
5e2cb101 | 1025 | return count; |
734efb46 | 1026 | } |
1027 | ||
1028 | /* | |
1029 | * Sysfs setup bits: | |
1030 | */ | |
d369a5d8 | 1031 | static DEVICE_ATTR(current_clocksource, 0644, sysfs_show_current_clocksources, |
f5f1a24a | 1032 | sysfs_override_clocksource); |
734efb46 | 1033 | |
7eaeb343 TG |
1034 | static DEVICE_ATTR(unbind_clocksource, 0200, NULL, sysfs_unbind_clocksource); |
1035 | ||
d369a5d8 | 1036 | static DEVICE_ATTR(available_clocksource, 0444, |
f5f1a24a | 1037 | sysfs_show_available_clocksources, NULL); |
734efb46 | 1038 | |
d369a5d8 | 1039 | static struct bus_type clocksource_subsys = { |
af5ca3f4 | 1040 | .name = "clocksource", |
d369a5d8 | 1041 | .dev_name = "clocksource", |
734efb46 | 1042 | }; |
1043 | ||
d369a5d8 | 1044 | static struct device device_clocksource = { |
734efb46 | 1045 | .id = 0, |
d369a5d8 | 1046 | .bus = &clocksource_subsys, |
734efb46 | 1047 | }; |
1048 | ||
ad596171 | 1049 | static int __init init_clocksource_sysfs(void) |
734efb46 | 1050 | { |
d369a5d8 | 1051 | int error = subsys_system_register(&clocksource_subsys, NULL); |
734efb46 | 1052 | |
1053 | if (!error) | |
d369a5d8 | 1054 | error = device_register(&device_clocksource); |
734efb46 | 1055 | if (!error) |
d369a5d8 | 1056 | error = device_create_file( |
734efb46 | 1057 | &device_clocksource, |
d369a5d8 | 1058 | &dev_attr_current_clocksource); |
7eaeb343 TG |
1059 | if (!error) |
1060 | error = device_create_file(&device_clocksource, | |
1061 | &dev_attr_unbind_clocksource); | |
734efb46 | 1062 | if (!error) |
d369a5d8 | 1063 | error = device_create_file( |
734efb46 | 1064 | &device_clocksource, |
d369a5d8 | 1065 | &dev_attr_available_clocksource); |
734efb46 | 1066 | return error; |
1067 | } | |
1068 | ||
1069 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 1070 | #endif /* CONFIG_SYSFS */ |
734efb46 | 1071 | |
1072 | /** | |
1073 | * boot_override_clocksource - boot clock override | |
1074 | * @str: override name | |
1075 | * | |
1076 | * Takes a clocksource= boot argument and uses it | |
1077 | * as the clocksource override name. | |
1078 | */ | |
1079 | static int __init boot_override_clocksource(char* str) | |
1080 | { | |
75c5158f | 1081 | mutex_lock(&clocksource_mutex); |
734efb46 | 1082 | if (str) |
1083 | strlcpy(override_name, str, sizeof(override_name)); | |
75c5158f | 1084 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1085 | return 1; |
1086 | } | |
1087 | ||
1088 | __setup("clocksource=", boot_override_clocksource); | |
1089 | ||
1090 | /** | |
1091 | * boot_override_clock - Compatibility layer for deprecated boot option | |
1092 | * @str: override name | |
1093 | * | |
1094 | * DEPRECATED! Takes a clock= boot argument and uses it | |
1095 | * as the clocksource override name | |
1096 | */ | |
1097 | static int __init boot_override_clock(char* str) | |
1098 | { | |
5d0cf410 | 1099 | if (!strcmp(str, "pmtmr")) { |
1100 | printk("Warning: clock=pmtmr is deprecated. " | |
1101 | "Use clocksource=acpi_pm.\n"); | |
1102 | return boot_override_clocksource("acpi_pm"); | |
1103 | } | |
1104 | printk("Warning! clock= boot option is deprecated. " | |
1105 | "Use clocksource=xyz\n"); | |
734efb46 | 1106 | return boot_override_clocksource(str); |
1107 | } | |
1108 | ||
1109 | __setup("clock=", boot_override_clock); |