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 | ||
45bbfe64 JP |
26 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
27 | ||
d369a5d8 | 28 | #include <linux/device.h> |
734efb46 | 29 | #include <linux/clocksource.h> |
734efb46 | 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 | 94 | /*[Clocksource internal variables]--------- |
95 | * curr_clocksource: | |
f1b82746 | 96 | * currently selected clocksource. |
734efb46 | 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 | 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 | |
2aae7bcf PZ |
122 | static void inline clocksource_watchdog_lock(unsigned long *flags) |
123 | { | |
124 | spin_lock_irqsave(&watchdog_lock, *flags); | |
125 | } | |
126 | ||
127 | static void inline clocksource_watchdog_unlock(unsigned long *flags) | |
128 | { | |
129 | spin_unlock_irqrestore(&watchdog_lock, *flags); | |
130 | } | |
131 | ||
5d8b34fd | 132 | /* |
35c35d1a | 133 | * Interval: 0.5sec Threshold: 0.0625s |
5d8b34fd TG |
134 | */ |
135 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
35c35d1a | 136 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) |
5d8b34fd | 137 | |
7285dd7f | 138 | static void __clocksource_unstable(struct clocksource *cs) |
5d8b34fd | 139 | { |
5d8b34fd | 140 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); |
c55c87c8 | 141 | cs->flags |= CLOCK_SOURCE_UNSTABLE; |
12907fbb | 142 | |
cd2af07d | 143 | /* |
7197e77a | 144 | * If the clocksource is registered clocksource_watchdog_work() will |
cd2af07d PZ |
145 | * re-rate and re-select. |
146 | */ | |
147 | if (list_empty(&cs->list)) { | |
148 | cs->rating = 0; | |
2aae7bcf | 149 | return; |
cd2af07d | 150 | } |
2aae7bcf | 151 | |
12907fbb TG |
152 | if (cs->mark_unstable) |
153 | cs->mark_unstable(cs); | |
154 | ||
7197e77a | 155 | /* kick clocksource_watchdog_work() */ |
54a6bc0b TG |
156 | if (finished_booting) |
157 | schedule_work(&watchdog_work); | |
5d8b34fd TG |
158 | } |
159 | ||
7285dd7f TG |
160 | /** |
161 | * clocksource_mark_unstable - mark clocksource unstable via watchdog | |
162 | * @cs: clocksource to be marked unstable | |
163 | * | |
7dba33c6 | 164 | * This function is called by the x86 TSC code to mark clocksources as unstable; |
7197e77a | 165 | * it defers demotion and re-selection to a work. |
7285dd7f TG |
166 | */ |
167 | void clocksource_mark_unstable(struct clocksource *cs) | |
168 | { | |
169 | unsigned long flags; | |
170 | ||
171 | spin_lock_irqsave(&watchdog_lock, flags); | |
172 | if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) { | |
2aae7bcf | 173 | if (!list_empty(&cs->list) && list_empty(&cs->wd_list)) |
7285dd7f TG |
174 | list_add(&cs->wd_list, &watchdog_list); |
175 | __clocksource_unstable(cs); | |
176 | } | |
177 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
178 | } | |
179 | ||
e99e88a9 | 180 | static void clocksource_watchdog(struct timer_list *unused) |
5d8b34fd | 181 | { |
c55c87c8 | 182 | struct clocksource *cs; |
a5a1d1c2 | 183 | u64 csnow, wdnow, cslast, wdlast, delta; |
5d8b34fd | 184 | int64_t wd_nsec, cs_nsec; |
9fb60336 | 185 | int next_cpu, reset_pending; |
5d8b34fd TG |
186 | |
187 | spin_lock(&watchdog_lock); | |
fb63a0eb MS |
188 | if (!watchdog_running) |
189 | goto out; | |
5d8b34fd | 190 | |
9fb60336 TG |
191 | reset_pending = atomic_read(&watchdog_reset_pending); |
192 | ||
c55c87c8 MS |
193 | list_for_each_entry(cs, &watchdog_list, wd_list) { |
194 | ||
195 | /* Clocksource already marked unstable? */ | |
01548f4d | 196 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
54a6bc0b TG |
197 | if (finished_booting) |
198 | schedule_work(&watchdog_work); | |
c55c87c8 | 199 | continue; |
01548f4d | 200 | } |
c55c87c8 | 201 | |
b5199515 | 202 | local_irq_disable(); |
8e19608e | 203 | csnow = cs->read(cs); |
b5199515 TG |
204 | wdnow = watchdog->read(watchdog); |
205 | local_irq_enable(); | |
b52f52a0 | 206 | |
8cf4e750 | 207 | /* Clocksource initialized ? */ |
9fb60336 TG |
208 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) || |
209 | atomic_read(&watchdog_reset_pending)) { | |
8cf4e750 | 210 | cs->flags |= CLOCK_SOURCE_WATCHDOG; |
b5199515 TG |
211 | cs->wd_last = wdnow; |
212 | cs->cs_last = csnow; | |
b52f52a0 TG |
213 | continue; |
214 | } | |
215 | ||
3a978377 TG |
216 | delta = clocksource_delta(wdnow, cs->wd_last, watchdog->mask); |
217 | wd_nsec = clocksource_cyc2ns(delta, watchdog->mult, | |
218 | watchdog->shift); | |
b5199515 | 219 | |
3a978377 TG |
220 | delta = clocksource_delta(csnow, cs->cs_last, cs->mask); |
221 | cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift); | |
0b046b21 JS |
222 | wdlast = cs->wd_last; /* save these in case we print them */ |
223 | cslast = cs->cs_last; | |
b5199515 TG |
224 | cs->cs_last = csnow; |
225 | cs->wd_last = wdnow; | |
226 | ||
9fb60336 TG |
227 | if (atomic_read(&watchdog_reset_pending)) |
228 | continue; | |
229 | ||
b5199515 | 230 | /* Check the deviation from the watchdog clocksource. */ |
79211c8e | 231 | if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) { |
390dd67c SI |
232 | pr_warn("timekeeping watchdog on CPU%d: Marking clocksource '%s' as unstable because the skew is too large:\n", |
233 | smp_processor_id(), cs->name); | |
45bbfe64 | 234 | pr_warn(" '%s' wd_now: %llx wd_last: %llx mask: %llx\n", |
0b046b21 | 235 | watchdog->name, wdnow, wdlast, watchdog->mask); |
45bbfe64 | 236 | pr_warn(" '%s' cs_now: %llx cs_last: %llx mask: %llx\n", |
0b046b21 JS |
237 | cs->name, csnow, cslast, cs->mask); |
238 | __clocksource_unstable(cs); | |
8cf4e750 MS |
239 | continue; |
240 | } | |
241 | ||
b421b22b PZ |
242 | if (cs == curr_clocksource && cs->tick_stable) |
243 | cs->tick_stable(cs); | |
244 | ||
8cf4e750 MS |
245 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && |
246 | (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
247 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
332962f2 | 248 | /* Mark it valid for high-res. */ |
8cf4e750 | 249 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
332962f2 TG |
250 | |
251 | /* | |
252 | * clocksource_done_booting() will sort it if | |
253 | * finished_booting is not set yet. | |
254 | */ | |
255 | if (!finished_booting) | |
256 | continue; | |
257 | ||
8cf4e750 | 258 | /* |
332962f2 TG |
259 | * If this is not the current clocksource let |
260 | * the watchdog thread reselect it. Due to the | |
261 | * change to high res this clocksource might | |
262 | * be preferred now. If it is the current | |
263 | * clocksource let the tick code know about | |
264 | * that change. | |
8cf4e750 | 265 | */ |
332962f2 TG |
266 | if (cs != curr_clocksource) { |
267 | cs->flags |= CLOCK_SOURCE_RESELECT; | |
268 | schedule_work(&watchdog_work); | |
269 | } else { | |
270 | tick_clock_notify(); | |
271 | } | |
5d8b34fd TG |
272 | } |
273 | } | |
274 | ||
9fb60336 TG |
275 | /* |
276 | * We only clear the watchdog_reset_pending, when we did a | |
277 | * full cycle through all clocksources. | |
278 | */ | |
279 | if (reset_pending) | |
280 | atomic_dec(&watchdog_reset_pending); | |
281 | ||
c55c87c8 MS |
282 | /* |
283 | * Cycle through CPUs to check if the CPUs stay synchronized | |
284 | * to each other. | |
285 | */ | |
286 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); | |
287 | if (next_cpu >= nr_cpu_ids) | |
288 | next_cpu = cpumask_first(cpu_online_mask); | |
289 | watchdog_timer.expires += WATCHDOG_INTERVAL; | |
290 | add_timer_on(&watchdog_timer, next_cpu); | |
fb63a0eb | 291 | out: |
5d8b34fd TG |
292 | spin_unlock(&watchdog_lock); |
293 | } | |
0f8e8ef7 | 294 | |
fb63a0eb MS |
295 | static inline void clocksource_start_watchdog(void) |
296 | { | |
297 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) | |
298 | return; | |
e99e88a9 | 299 | timer_setup(&watchdog_timer, clocksource_watchdog, 0); |
fb63a0eb MS |
300 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; |
301 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); | |
302 | watchdog_running = 1; | |
303 | } | |
304 | ||
305 | static inline void clocksource_stop_watchdog(void) | |
306 | { | |
307 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) | |
308 | return; | |
309 | del_timer(&watchdog_timer); | |
310 | watchdog_running = 0; | |
311 | } | |
312 | ||
0f8e8ef7 MS |
313 | static inline void clocksource_reset_watchdog(void) |
314 | { | |
315 | struct clocksource *cs; | |
316 | ||
317 | list_for_each_entry(cs, &watchdog_list, wd_list) | |
318 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
319 | } | |
320 | ||
b52f52a0 TG |
321 | static void clocksource_resume_watchdog(void) |
322 | { | |
9fb60336 | 323 | atomic_inc(&watchdog_reset_pending); |
b52f52a0 TG |
324 | } |
325 | ||
fb63a0eb | 326 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
5d8b34fd | 327 | { |
5b9e886a PZ |
328 | INIT_LIST_HEAD(&cs->wd_list); |
329 | ||
5d8b34fd | 330 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { |
fb63a0eb | 331 | /* cs is a clocksource to be watched. */ |
5d8b34fd | 332 | list_add(&cs->wd_list, &watchdog_list); |
fb63a0eb | 333 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
948ac6d7 | 334 | } else { |
fb63a0eb | 335 | /* cs is a watchdog. */ |
948ac6d7 | 336 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
5d8b34fd | 337 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
bbf66d89 | 338 | } |
bbf66d89 VK |
339 | } |
340 | ||
341 | static void clocksource_select_watchdog(bool fallback) | |
342 | { | |
343 | struct clocksource *cs, *old_wd; | |
344 | unsigned long flags; | |
345 | ||
346 | spin_lock_irqsave(&watchdog_lock, flags); | |
347 | /* save current watchdog */ | |
348 | old_wd = watchdog; | |
349 | if (fallback) | |
350 | watchdog = NULL; | |
351 | ||
352 | list_for_each_entry(cs, &clocksource_list, list) { | |
353 | /* cs is a clocksource to be watched. */ | |
354 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) | |
355 | continue; | |
356 | ||
357 | /* Skip current if we were requested for a fallback. */ | |
358 | if (fallback && cs == old_wd) | |
359 | continue; | |
360 | ||
fb63a0eb | 361 | /* Pick the best watchdog. */ |
bbf66d89 | 362 | if (!watchdog || cs->rating > watchdog->rating) |
5d8b34fd | 363 | watchdog = cs; |
5d8b34fd | 364 | } |
bbf66d89 VK |
365 | /* If we failed to find a fallback restore the old one. */ |
366 | if (!watchdog) | |
367 | watchdog = old_wd; | |
368 | ||
369 | /* If we changed the watchdog we need to reset cycles. */ | |
370 | if (watchdog != old_wd) | |
371 | clocksource_reset_watchdog(); | |
372 | ||
fb63a0eb MS |
373 | /* Check if the watchdog timer needs to be started. */ |
374 | clocksource_start_watchdog(); | |
5d8b34fd TG |
375 | spin_unlock_irqrestore(&watchdog_lock, flags); |
376 | } | |
fb63a0eb MS |
377 | |
378 | static void clocksource_dequeue_watchdog(struct clocksource *cs) | |
379 | { | |
a89c7edb TG |
380 | if (cs != watchdog) { |
381 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
382 | /* cs is a watched clocksource. */ | |
383 | list_del_init(&cs->wd_list); | |
384 | /* Check if the watchdog timer needs to be stopped. */ | |
385 | clocksource_stop_watchdog(); | |
fb63a0eb MS |
386 | } |
387 | } | |
fb63a0eb MS |
388 | } |
389 | ||
7197e77a PZ |
390 | static void __clocksource_change_rating(struct clocksource *cs, int rating); |
391 | ||
392 | static int __clocksource_watchdog_work(void) | |
c55c87c8 MS |
393 | { |
394 | struct clocksource *cs, *tmp; | |
395 | unsigned long flags; | |
332962f2 | 396 | int select = 0; |
c55c87c8 MS |
397 | |
398 | spin_lock_irqsave(&watchdog_lock, flags); | |
332962f2 | 399 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { |
c55c87c8 MS |
400 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
401 | list_del_init(&cs->wd_list); | |
2aae7bcf | 402 | __clocksource_change_rating(cs, 0); |
332962f2 TG |
403 | select = 1; |
404 | } | |
405 | if (cs->flags & CLOCK_SOURCE_RESELECT) { | |
406 | cs->flags &= ~CLOCK_SOURCE_RESELECT; | |
407 | select = 1; | |
c55c87c8 | 408 | } |
332962f2 | 409 | } |
c55c87c8 MS |
410 | /* Check if the watchdog timer needs to be stopped. */ |
411 | clocksource_stop_watchdog(); | |
6ea41d25 TG |
412 | spin_unlock_irqrestore(&watchdog_lock, flags); |
413 | ||
332962f2 TG |
414 | return select; |
415 | } | |
416 | ||
7197e77a | 417 | static void clocksource_watchdog_work(struct work_struct *work) |
332962f2 TG |
418 | { |
419 | mutex_lock(&clocksource_mutex); | |
7197e77a | 420 | if (__clocksource_watchdog_work()) |
332962f2 | 421 | clocksource_select(); |
d0981a1b | 422 | mutex_unlock(&clocksource_mutex); |
c55c87c8 MS |
423 | } |
424 | ||
7eaeb343 TG |
425 | static bool clocksource_is_watchdog(struct clocksource *cs) |
426 | { | |
427 | return cs == watchdog; | |
428 | } | |
429 | ||
fb63a0eb MS |
430 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
431 | ||
432 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
5d8b34fd TG |
433 | { |
434 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
435 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
436 | } | |
b52f52a0 | 437 | |
bbf66d89 | 438 | static void clocksource_select_watchdog(bool fallback) { } |
fb63a0eb | 439 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
b52f52a0 | 440 | static inline void clocksource_resume_watchdog(void) { } |
7197e77a | 441 | static inline int __clocksource_watchdog_work(void) { return 0; } |
7eaeb343 | 442 | static bool clocksource_is_watchdog(struct clocksource *cs) { return false; } |
397bbf6d | 443 | void clocksource_mark_unstable(struct clocksource *cs) { } |
fb63a0eb | 444 | |
db6f9e55 MM |
445 | static inline void clocksource_watchdog_lock(unsigned long *flags) { } |
446 | static inline void clocksource_watchdog_unlock(unsigned long *flags) { } | |
2aae7bcf | 447 | |
fb63a0eb | 448 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
5d8b34fd | 449 | |
c54a42b1 MD |
450 | /** |
451 | * clocksource_suspend - suspend the clocksource(s) | |
452 | */ | |
453 | void clocksource_suspend(void) | |
454 | { | |
455 | struct clocksource *cs; | |
456 | ||
457 | list_for_each_entry_reverse(cs, &clocksource_list, list) | |
458 | if (cs->suspend) | |
459 | cs->suspend(cs); | |
460 | } | |
461 | ||
b52f52a0 TG |
462 | /** |
463 | * clocksource_resume - resume the clocksource(s) | |
464 | */ | |
465 | void clocksource_resume(void) | |
466 | { | |
2e197586 | 467 | struct clocksource *cs; |
b52f52a0 | 468 | |
75c5158f | 469 | list_for_each_entry(cs, &clocksource_list, list) |
b52f52a0 | 470 | if (cs->resume) |
17622339 | 471 | cs->resume(cs); |
b52f52a0 TG |
472 | |
473 | clocksource_resume_watchdog(); | |
b52f52a0 TG |
474 | } |
475 | ||
7c3078b6 JW |
476 | /** |
477 | * clocksource_touch_watchdog - Update watchdog | |
478 | * | |
479 | * Update the watchdog after exception contexts such as kgdb so as not | |
7b7422a5 TG |
480 | * to incorrectly trip the watchdog. This might fail when the kernel |
481 | * was stopped in code which holds watchdog_lock. | |
7c3078b6 JW |
482 | */ |
483 | void clocksource_touch_watchdog(void) | |
484 | { | |
485 | clocksource_resume_watchdog(); | |
486 | } | |
487 | ||
d65670a7 JS |
488 | /** |
489 | * clocksource_max_adjustment- Returns max adjustment amount | |
490 | * @cs: Pointer to clocksource | |
491 | * | |
492 | */ | |
493 | static u32 clocksource_max_adjustment(struct clocksource *cs) | |
494 | { | |
495 | u64 ret; | |
496 | /* | |
88b28adf | 497 | * We won't try to correct for more than 11% adjustments (110,000 ppm), |
d65670a7 JS |
498 | */ |
499 | ret = (u64)cs->mult * 11; | |
500 | do_div(ret,100); | |
501 | return (u32)ret; | |
502 | } | |
503 | ||
98962465 | 504 | /** |
87d8b9eb SB |
505 | * clocks_calc_max_nsecs - Returns maximum nanoseconds that can be converted |
506 | * @mult: cycle to nanosecond multiplier | |
507 | * @shift: cycle to nanosecond divisor (power of two) | |
508 | * @maxadj: maximum adjustment value to mult (~11%) | |
509 | * @mask: bitmask for two's complement subtraction of non 64 bit counters | |
fb82fe2f JS |
510 | * @max_cyc: maximum cycle value before potential overflow (does not include |
511 | * any safety margin) | |
362fde04 | 512 | * |
8e56f33f JS |
513 | * NOTE: This function includes a safety margin of 50%, in other words, we |
514 | * return half the number of nanoseconds the hardware counter can technically | |
515 | * cover. This is done so that we can potentially detect problems caused by | |
516 | * delayed timers or bad hardware, which might result in time intervals that | |
571af55a | 517 | * are larger than what the math used can handle without overflows. |
98962465 | 518 | */ |
fb82fe2f | 519 | u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cyc) |
98962465 JH |
520 | { |
521 | u64 max_nsecs, max_cycles; | |
522 | ||
523 | /* | |
524 | * Calculate the maximum number of cycles that we can pass to the | |
6086e346 | 525 | * cyc2ns() function without overflowing a 64-bit result. |
98962465 | 526 | */ |
6086e346 JS |
527 | max_cycles = ULLONG_MAX; |
528 | do_div(max_cycles, mult+maxadj); | |
98962465 JH |
529 | |
530 | /* | |
531 | * The actual maximum number of cycles we can defer the clocksource is | |
87d8b9eb | 532 | * determined by the minimum of max_cycles and mask. |
d65670a7 JS |
533 | * Note: Here we subtract the maxadj to make sure we don't sleep for |
534 | * too long if there's a large negative adjustment. | |
98962465 | 535 | */ |
87d8b9eb SB |
536 | max_cycles = min(max_cycles, mask); |
537 | max_nsecs = clocksource_cyc2ns(max_cycles, mult - maxadj, shift); | |
538 | ||
fb82fe2f JS |
539 | /* return the max_cycles value as well if requested */ |
540 | if (max_cyc) | |
541 | *max_cyc = max_cycles; | |
542 | ||
362fde04 JS |
543 | /* Return 50% of the actual maximum, so we can detect bad values */ |
544 | max_nsecs >>= 1; | |
545 | ||
87d8b9eb SB |
546 | return max_nsecs; |
547 | } | |
548 | ||
549 | /** | |
fb82fe2f JS |
550 | * clocksource_update_max_deferment - Updates the clocksource max_idle_ns & max_cycles |
551 | * @cs: Pointer to clocksource to be updated | |
87d8b9eb SB |
552 | * |
553 | */ | |
fb82fe2f | 554 | static inline void clocksource_update_max_deferment(struct clocksource *cs) |
87d8b9eb | 555 | { |
fb82fe2f JS |
556 | cs->max_idle_ns = clocks_calc_max_nsecs(cs->mult, cs->shift, |
557 | cs->maxadj, cs->mask, | |
558 | &cs->max_cycles); | |
98962465 JH |
559 | } |
560 | ||
592913ec | 561 | #ifndef CONFIG_ARCH_USES_GETTIMEOFFSET |
734efb46 | 562 | |
f5a2e343 | 563 | static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur) |
5d33b883 TG |
564 | { |
565 | struct clocksource *cs; | |
566 | ||
567 | if (!finished_booting || list_empty(&clocksource_list)) | |
568 | return NULL; | |
569 | ||
570 | /* | |
571 | * We pick the clocksource with the highest rating. If oneshot | |
572 | * mode is active, we pick the highres valid clocksource with | |
573 | * the best rating. | |
574 | */ | |
575 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
576 | if (skipcur && cs == curr_clocksource) |
577 | continue; | |
5d33b883 TG |
578 | if (oneshot && !(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES)) |
579 | continue; | |
580 | return cs; | |
581 | } | |
582 | return NULL; | |
583 | } | |
584 | ||
f5a2e343 | 585 | static void __clocksource_select(bool skipcur) |
734efb46 | 586 | { |
5d33b883 | 587 | bool oneshot = tick_oneshot_mode_active(); |
f1b82746 | 588 | struct clocksource *best, *cs; |
5d8b34fd | 589 | |
5d33b883 | 590 | /* Find the best suitable clocksource */ |
f5a2e343 | 591 | best = clocksource_find_best(oneshot, skipcur); |
5d33b883 | 592 | if (!best) |
f1b82746 | 593 | return; |
5d33b883 | 594 | |
7f852afe BW |
595 | if (!strlen(override_name)) |
596 | goto found; | |
597 | ||
f1b82746 MS |
598 | /* Check for the override clocksource. */ |
599 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
600 | if (skipcur && cs == curr_clocksource) |
601 | continue; | |
f1b82746 MS |
602 | if (strcmp(cs->name, override_name) != 0) |
603 | continue; | |
604 | /* | |
605 | * Check to make sure we don't switch to a non-highres | |
606 | * capable clocksource if the tick code is in oneshot | |
607 | * mode (highres or nohz) | |
608 | */ | |
5d33b883 | 609 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && oneshot) { |
f1b82746 | 610 | /* Override clocksource cannot be used. */ |
36374583 KW |
611 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
612 | pr_warn("Override clocksource %s is unstable and not HRT compatible - cannot switch while in HRT/NOHZ mode\n", | |
613 | cs->name); | |
614 | override_name[0] = 0; | |
615 | } else { | |
616 | /* | |
617 | * The override cannot be currently verified. | |
618 | * Deferring to let the watchdog check. | |
619 | */ | |
620 | pr_info("Override clocksource %s is not currently HRT compatible - deferring\n", | |
621 | cs->name); | |
622 | } | |
f1b82746 MS |
623 | } else |
624 | /* Override clocksource can be used. */ | |
625 | best = cs; | |
626 | break; | |
627 | } | |
ba919d1c | 628 | |
7f852afe | 629 | found: |
ba919d1c TG |
630 | if (curr_clocksource != best && !timekeeping_notify(best)) { |
631 | pr_info("Switched to clocksource %s\n", best->name); | |
75c5158f | 632 | curr_clocksource = best; |
75c5158f | 633 | } |
f1b82746 | 634 | } |
734efb46 | 635 | |
f5a2e343 TG |
636 | /** |
637 | * clocksource_select - Select the best clocksource available | |
638 | * | |
639 | * Private function. Must hold clocksource_mutex when called. | |
640 | * | |
641 | * Select the clocksource with the best rating, or the clocksource, | |
642 | * which is selected by userspace override. | |
643 | */ | |
644 | static void clocksource_select(void) | |
645 | { | |
cfed432d | 646 | __clocksource_select(false); |
f5a2e343 TG |
647 | } |
648 | ||
7eaeb343 TG |
649 | static void clocksource_select_fallback(void) |
650 | { | |
cfed432d | 651 | __clocksource_select(true); |
7eaeb343 TG |
652 | } |
653 | ||
592913ec | 654 | #else /* !CONFIG_ARCH_USES_GETTIMEOFFSET */ |
54a6bc0b | 655 | static inline void clocksource_select(void) { } |
1eaff672 | 656 | static inline void clocksource_select_fallback(void) { } |
54a6bc0b TG |
657 | |
658 | #endif | |
659 | ||
75c5158f MS |
660 | /* |
661 | * clocksource_done_booting - Called near the end of core bootup | |
662 | * | |
663 | * Hack to avoid lots of clocksource churn at boot time. | |
664 | * We use fs_initcall because we want this to start before | |
665 | * device_initcall but after subsys_initcall. | |
666 | */ | |
667 | static int __init clocksource_done_booting(void) | |
668 | { | |
ad6759fb | 669 | mutex_lock(&clocksource_mutex); |
670 | curr_clocksource = clocksource_default_clock(); | |
75c5158f | 671 | finished_booting = 1; |
54a6bc0b TG |
672 | /* |
673 | * Run the watchdog first to eliminate unstable clock sources | |
674 | */ | |
7197e77a | 675 | __clocksource_watchdog_work(); |
75c5158f | 676 | clocksource_select(); |
e6c73305 | 677 | mutex_unlock(&clocksource_mutex); |
75c5158f MS |
678 | return 0; |
679 | } | |
680 | fs_initcall(clocksource_done_booting); | |
681 | ||
92c7e002 TG |
682 | /* |
683 | * Enqueue the clocksource sorted by rating | |
734efb46 | 684 | */ |
f1b82746 | 685 | static void clocksource_enqueue(struct clocksource *cs) |
734efb46 | 686 | { |
f1b82746 MS |
687 | struct list_head *entry = &clocksource_list; |
688 | struct clocksource *tmp; | |
92c7e002 | 689 | |
0fb71d34 | 690 | list_for_each_entry(tmp, &clocksource_list, list) { |
92c7e002 | 691 | /* Keep track of the place, where to insert */ |
0fb71d34 MH |
692 | if (tmp->rating < cs->rating) |
693 | break; | |
694 | entry = &tmp->list; | |
695 | } | |
f1b82746 | 696 | list_add(&cs->list, entry); |
734efb46 | 697 | } |
698 | ||
d7e81c26 | 699 | /** |
fba9e072 | 700 | * __clocksource_update_freq_scale - Used update clocksource with new freq |
b1b73d09 | 701 | * @cs: clocksource to be registered |
d7e81c26 JS |
702 | * @scale: Scale factor multiplied against freq to get clocksource hz |
703 | * @freq: clocksource frequency (cycles per second) divided by scale | |
704 | * | |
852db46d | 705 | * This should only be called from the clocksource->enable() method. |
d7e81c26 JS |
706 | * |
707 | * This *SHOULD NOT* be called directly! Please use the | |
fba9e072 JS |
708 | * __clocksource_update_freq_hz() or __clocksource_update_freq_khz() helper |
709 | * functions. | |
d7e81c26 | 710 | */ |
fba9e072 | 711 | void __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq) |
d7e81c26 | 712 | { |
c0e299b1 | 713 | u64 sec; |
f8935983 | 714 | |
d7e81c26 | 715 | /* |
f8935983 JS |
716 | * Default clocksources are *special* and self-define their mult/shift. |
717 | * But, you're not special, so you should specify a freq value. | |
d7e81c26 | 718 | */ |
f8935983 JS |
719 | if (freq) { |
720 | /* | |
721 | * Calc the maximum number of seconds which we can run before | |
722 | * wrapping around. For clocksources which have a mask > 32-bit | |
723 | * we need to limit the max sleep time to have a good | |
724 | * conversion precision. 10 minutes is still a reasonable | |
725 | * amount. That results in a shift value of 24 for a | |
726 | * clocksource with mask >= 40-bit and f >= 4GHz. That maps to | |
727 | * ~ 0.06ppm granularity for NTP. | |
728 | */ | |
729 | sec = cs->mask; | |
730 | do_div(sec, freq); | |
731 | do_div(sec, scale); | |
732 | if (!sec) | |
733 | sec = 1; | |
734 | else if (sec > 600 && cs->mask > UINT_MAX) | |
735 | sec = 600; | |
736 | ||
737 | clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, | |
738 | NSEC_PER_SEC / scale, sec * scale); | |
739 | } | |
d65670a7 | 740 | /* |
362fde04 JS |
741 | * Ensure clocksources that have large 'mult' values don't overflow |
742 | * when adjusted. | |
d65670a7 JS |
743 | */ |
744 | cs->maxadj = clocksource_max_adjustment(cs); | |
f8935983 JS |
745 | while (freq && ((cs->mult + cs->maxadj < cs->mult) |
746 | || (cs->mult - cs->maxadj > cs->mult))) { | |
d65670a7 JS |
747 | cs->mult >>= 1; |
748 | cs->shift--; | |
749 | cs->maxadj = clocksource_max_adjustment(cs); | |
750 | } | |
751 | ||
f8935983 JS |
752 | /* |
753 | * Only warn for *special* clocksources that self-define | |
754 | * their mult/shift values and don't specify a freq. | |
755 | */ | |
756 | WARN_ONCE(cs->mult + cs->maxadj < cs->mult, | |
757 | "timekeeping: Clocksource %s might overflow on 11%% adjustment\n", | |
758 | cs->name); | |
759 | ||
fb82fe2f | 760 | clocksource_update_max_deferment(cs); |
8cc8c525 | 761 | |
45bbfe64 JP |
762 | pr_info("%s: mask: 0x%llx max_cycles: 0x%llx, max_idle_ns: %lld ns\n", |
763 | cs->name, cs->mask, cs->max_cycles, cs->max_idle_ns); | |
852db46d | 764 | } |
fba9e072 | 765 | EXPORT_SYMBOL_GPL(__clocksource_update_freq_scale); |
852db46d JS |
766 | |
767 | /** | |
768 | * __clocksource_register_scale - Used to install new clocksources | |
b1b73d09 | 769 | * @cs: clocksource to be registered |
852db46d JS |
770 | * @scale: Scale factor multiplied against freq to get clocksource hz |
771 | * @freq: clocksource frequency (cycles per second) divided by scale | |
772 | * | |
773 | * Returns -EBUSY if registration fails, zero otherwise. | |
774 | * | |
775 | * This *SHOULD NOT* be called directly! Please use the | |
776 | * clocksource_register_hz() or clocksource_register_khz helper functions. | |
777 | */ | |
778 | int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) | |
779 | { | |
2aae7bcf | 780 | unsigned long flags; |
852db46d | 781 | |
b595076a | 782 | /* Initialize mult/shift and max_idle_ns */ |
fba9e072 | 783 | __clocksource_update_freq_scale(cs, scale, freq); |
d7e81c26 | 784 | |
be278e98 | 785 | /* Add clocksource to the clocksource list */ |
d7e81c26 | 786 | mutex_lock(&clocksource_mutex); |
2aae7bcf PZ |
787 | |
788 | clocksource_watchdog_lock(&flags); | |
d7e81c26 | 789 | clocksource_enqueue(cs); |
d7e81c26 | 790 | clocksource_enqueue_watchdog(cs); |
2aae7bcf PZ |
791 | clocksource_watchdog_unlock(&flags); |
792 | ||
e05b2efb | 793 | clocksource_select(); |
bbf66d89 | 794 | clocksource_select_watchdog(false); |
d7e81c26 JS |
795 | mutex_unlock(&clocksource_mutex); |
796 | return 0; | |
797 | } | |
798 | EXPORT_SYMBOL_GPL(__clocksource_register_scale); | |
799 | ||
d0981a1b TG |
800 | static void __clocksource_change_rating(struct clocksource *cs, int rating) |
801 | { | |
802 | list_del(&cs->list); | |
803 | cs->rating = rating; | |
804 | clocksource_enqueue(cs); | |
d0981a1b TG |
805 | } |
806 | ||
734efb46 | 807 | /** |
92c7e002 | 808 | * clocksource_change_rating - Change the rating of a registered clocksource |
b1b73d09 KK |
809 | * @cs: clocksource to be changed |
810 | * @rating: new rating | |
734efb46 | 811 | */ |
92c7e002 | 812 | void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb46 | 813 | { |
2aae7bcf PZ |
814 | unsigned long flags; |
815 | ||
75c5158f | 816 | mutex_lock(&clocksource_mutex); |
2aae7bcf | 817 | clocksource_watchdog_lock(&flags); |
d0981a1b | 818 | __clocksource_change_rating(cs, rating); |
2aae7bcf PZ |
819 | clocksource_watchdog_unlock(&flags); |
820 | ||
332962f2 | 821 | clocksource_select(); |
bbf66d89 | 822 | clocksource_select_watchdog(false); |
75c5158f | 823 | mutex_unlock(&clocksource_mutex); |
734efb46 | 824 | } |
fb63a0eb | 825 | EXPORT_SYMBOL(clocksource_change_rating); |
734efb46 | 826 | |
7eaeb343 TG |
827 | /* |
828 | * Unbind clocksource @cs. Called with clocksource_mutex held | |
829 | */ | |
830 | static int clocksource_unbind(struct clocksource *cs) | |
831 | { | |
2aae7bcf PZ |
832 | unsigned long flags; |
833 | ||
bbf66d89 VK |
834 | if (clocksource_is_watchdog(cs)) { |
835 | /* Select and try to install a replacement watchdog. */ | |
836 | clocksource_select_watchdog(true); | |
837 | if (clocksource_is_watchdog(cs)) | |
838 | return -EBUSY; | |
839 | } | |
7eaeb343 TG |
840 | |
841 | if (cs == curr_clocksource) { | |
842 | /* Select and try to install a replacement clock source */ | |
843 | clocksource_select_fallback(); | |
844 | if (curr_clocksource == cs) | |
845 | return -EBUSY; | |
846 | } | |
2aae7bcf PZ |
847 | |
848 | clocksource_watchdog_lock(&flags); | |
7eaeb343 TG |
849 | clocksource_dequeue_watchdog(cs); |
850 | list_del_init(&cs->list); | |
2aae7bcf PZ |
851 | clocksource_watchdog_unlock(&flags); |
852 | ||
7eaeb343 TG |
853 | return 0; |
854 | } | |
855 | ||
4713e22c TG |
856 | /** |
857 | * clocksource_unregister - remove a registered clocksource | |
b1b73d09 | 858 | * @cs: clocksource to be unregistered |
4713e22c | 859 | */ |
a89c7edb | 860 | int clocksource_unregister(struct clocksource *cs) |
4713e22c | 861 | { |
a89c7edb TG |
862 | int ret = 0; |
863 | ||
75c5158f | 864 | mutex_lock(&clocksource_mutex); |
a89c7edb TG |
865 | if (!list_empty(&cs->list)) |
866 | ret = clocksource_unbind(cs); | |
75c5158f | 867 | mutex_unlock(&clocksource_mutex); |
a89c7edb | 868 | return ret; |
4713e22c | 869 | } |
fb63a0eb | 870 | EXPORT_SYMBOL(clocksource_unregister); |
4713e22c | 871 | |
2b013700 | 872 | #ifdef CONFIG_SYSFS |
734efb46 | 873 | /** |
e87821d1 | 874 | * current_clocksource_show - sysfs interface for current clocksource |
734efb46 | 875 | * @dev: unused |
b1b73d09 | 876 | * @attr: unused |
734efb46 | 877 | * @buf: char buffer to be filled with clocksource list |
878 | * | |
879 | * Provides sysfs interface for listing current clocksource. | |
880 | */ | |
e87821d1 BW |
881 | static ssize_t current_clocksource_show(struct device *dev, |
882 | struct device_attribute *attr, | |
883 | char *buf) | |
734efb46 | 884 | { |
5e2cb101 | 885 | ssize_t count = 0; |
734efb46 | 886 | |
75c5158f | 887 | mutex_lock(&clocksource_mutex); |
5e2cb101 | 888 | count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); |
75c5158f | 889 | mutex_unlock(&clocksource_mutex); |
734efb46 | 890 | |
5e2cb101 | 891 | return count; |
734efb46 | 892 | } |
893 | ||
891292a7 | 894 | ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt) |
29b54078 TG |
895 | { |
896 | size_t ret = cnt; | |
897 | ||
898 | /* strings from sysfs write are not 0 terminated! */ | |
899 | if (!cnt || cnt >= CS_NAME_LEN) | |
900 | return -EINVAL; | |
901 | ||
902 | /* strip of \n: */ | |
903 | if (buf[cnt-1] == '\n') | |
904 | cnt--; | |
905 | if (cnt > 0) | |
906 | memcpy(dst, buf, cnt); | |
907 | dst[cnt] = 0; | |
908 | return ret; | |
909 | } | |
910 | ||
734efb46 | 911 | /** |
e87821d1 | 912 | * current_clocksource_store - interface for manually overriding clocksource |
734efb46 | 913 | * @dev: unused |
b1b73d09 | 914 | * @attr: unused |
734efb46 | 915 | * @buf: name of override clocksource |
916 | * @count: length of buffer | |
917 | * | |
918 | * Takes input from sysfs interface for manually overriding the default | |
b71a8eb0 | 919 | * clocksource selection. |
734efb46 | 920 | */ |
e87821d1 BW |
921 | static ssize_t current_clocksource_store(struct device *dev, |
922 | struct device_attribute *attr, | |
923 | const char *buf, size_t count) | |
734efb46 | 924 | { |
233bcb41 | 925 | ssize_t ret; |
734efb46 | 926 | |
75c5158f | 927 | mutex_lock(&clocksource_mutex); |
734efb46 | 928 | |
03e13cf5 | 929 | ret = sysfs_get_uname(buf, override_name, count); |
29b54078 TG |
930 | if (ret >= 0) |
931 | clocksource_select(); | |
734efb46 | 932 | |
75c5158f | 933 | mutex_unlock(&clocksource_mutex); |
734efb46 | 934 | |
935 | return ret; | |
936 | } | |
e87821d1 | 937 | static DEVICE_ATTR_RW(current_clocksource); |
734efb46 | 938 | |
7eaeb343 | 939 | /** |
e87821d1 | 940 | * unbind_clocksource_store - interface for manually unbinding clocksource |
7eaeb343 TG |
941 | * @dev: unused |
942 | * @attr: unused | |
943 | * @buf: unused | |
944 | * @count: length of buffer | |
945 | * | |
946 | * Takes input from sysfs interface for manually unbinding a clocksource. | |
947 | */ | |
e87821d1 | 948 | static ssize_t unbind_clocksource_store(struct device *dev, |
7eaeb343 TG |
949 | struct device_attribute *attr, |
950 | const char *buf, size_t count) | |
951 | { | |
952 | struct clocksource *cs; | |
953 | char name[CS_NAME_LEN]; | |
233bcb41 | 954 | ssize_t ret; |
7eaeb343 | 955 | |
03e13cf5 | 956 | ret = sysfs_get_uname(buf, name, count); |
7eaeb343 TG |
957 | if (ret < 0) |
958 | return ret; | |
959 | ||
960 | ret = -ENODEV; | |
961 | mutex_lock(&clocksource_mutex); | |
962 | list_for_each_entry(cs, &clocksource_list, list) { | |
963 | if (strcmp(cs->name, name)) | |
964 | continue; | |
965 | ret = clocksource_unbind(cs); | |
966 | break; | |
967 | } | |
968 | mutex_unlock(&clocksource_mutex); | |
969 | ||
970 | return ret ? ret : count; | |
971 | } | |
e87821d1 | 972 | static DEVICE_ATTR_WO(unbind_clocksource); |
7eaeb343 | 973 | |
734efb46 | 974 | /** |
e87821d1 | 975 | * available_clocksource_show - sysfs interface for listing clocksource |
734efb46 | 976 | * @dev: unused |
b1b73d09 | 977 | * @attr: unused |
734efb46 | 978 | * @buf: char buffer to be filled with clocksource list |
979 | * | |
980 | * Provides sysfs interface for listing registered clocksources | |
981 | */ | |
e87821d1 BW |
982 | static ssize_t available_clocksource_show(struct device *dev, |
983 | struct device_attribute *attr, | |
984 | char *buf) | |
734efb46 | 985 | { |
2e197586 | 986 | struct clocksource *src; |
5e2cb101 | 987 | ssize_t count = 0; |
734efb46 | 988 | |
75c5158f | 989 | mutex_lock(&clocksource_mutex); |
2e197586 | 990 | list_for_each_entry(src, &clocksource_list, list) { |
cd6d95d8 TG |
991 | /* |
992 | * Don't show non-HRES clocksource if the tick code is | |
993 | * in one shot mode (highres=on or nohz=on) | |
994 | */ | |
995 | if (!tick_oneshot_mode_active() || | |
996 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) | |
3f68535a | 997 | count += snprintf(buf + count, |
5e2cb101 MX |
998 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), |
999 | "%s ", src->name); | |
734efb46 | 1000 | } |
75c5158f | 1001 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1002 | |
5e2cb101 MX |
1003 | count += snprintf(buf + count, |
1004 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); | |
734efb46 | 1005 | |
5e2cb101 | 1006 | return count; |
734efb46 | 1007 | } |
e87821d1 | 1008 | static DEVICE_ATTR_RO(available_clocksource); |
734efb46 | 1009 | |
27263e8d BW |
1010 | static struct attribute *clocksource_attrs[] = { |
1011 | &dev_attr_current_clocksource.attr, | |
1012 | &dev_attr_unbind_clocksource.attr, | |
1013 | &dev_attr_available_clocksource.attr, | |
1014 | NULL | |
1015 | }; | |
1016 | ATTRIBUTE_GROUPS(clocksource); | |
1017 | ||
d369a5d8 | 1018 | static struct bus_type clocksource_subsys = { |
af5ca3f4 | 1019 | .name = "clocksource", |
d369a5d8 | 1020 | .dev_name = "clocksource", |
734efb46 | 1021 | }; |
1022 | ||
d369a5d8 | 1023 | static struct device device_clocksource = { |
734efb46 | 1024 | .id = 0, |
d369a5d8 | 1025 | .bus = &clocksource_subsys, |
27263e8d | 1026 | .groups = clocksource_groups, |
734efb46 | 1027 | }; |
1028 | ||
ad596171 | 1029 | static int __init init_clocksource_sysfs(void) |
734efb46 | 1030 | { |
d369a5d8 | 1031 | int error = subsys_system_register(&clocksource_subsys, NULL); |
734efb46 | 1032 | |
1033 | if (!error) | |
d369a5d8 | 1034 | error = device_register(&device_clocksource); |
27263e8d | 1035 | |
734efb46 | 1036 | return error; |
1037 | } | |
1038 | ||
1039 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 1040 | #endif /* CONFIG_SYSFS */ |
734efb46 | 1041 | |
1042 | /** | |
1043 | * boot_override_clocksource - boot clock override | |
1044 | * @str: override name | |
1045 | * | |
1046 | * Takes a clocksource= boot argument and uses it | |
1047 | * as the clocksource override name. | |
1048 | */ | |
1049 | static int __init boot_override_clocksource(char* str) | |
1050 | { | |
75c5158f | 1051 | mutex_lock(&clocksource_mutex); |
734efb46 | 1052 | if (str) |
1053 | strlcpy(override_name, str, sizeof(override_name)); | |
75c5158f | 1054 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1055 | return 1; |
1056 | } | |
1057 | ||
1058 | __setup("clocksource=", boot_override_clocksource); | |
1059 | ||
1060 | /** | |
1061 | * boot_override_clock - Compatibility layer for deprecated boot option | |
1062 | * @str: override name | |
1063 | * | |
1064 | * DEPRECATED! Takes a clock= boot argument and uses it | |
1065 | * as the clocksource override name | |
1066 | */ | |
1067 | static int __init boot_override_clock(char* str) | |
1068 | { | |
5d0cf410 | 1069 | if (!strcmp(str, "pmtmr")) { |
45bbfe64 | 1070 | pr_warn("clock=pmtmr is deprecated - use clocksource=acpi_pm\n"); |
5d0cf410 | 1071 | return boot_override_clocksource("acpi_pm"); |
1072 | } | |
45bbfe64 | 1073 | pr_warn("clock= boot option is deprecated - use clocksource=xyz\n"); |
734efb46 | 1074 | return boot_override_clocksource(str); |
1075 | } | |
1076 | ||
1077 | __setup("clock=", boot_override_clock); |