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35728b82 | 1 | // SPDX-License-Identifier: GPL-2.0+ |
734efb46 | 2 | /* |
734efb46 JS |
3 | * This file contains the functions which manage clocksource drivers. |
4 | * | |
5 | * Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) | |
734efb46 JS |
6 | */ |
7 | ||
45bbfe64 JP |
8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
9 | ||
d369a5d8 | 10 | #include <linux/device.h> |
734efb46 | 11 | #include <linux/clocksource.h> |
734efb46 JS |
12 | #include <linux/init.h> |
13 | #include <linux/module.h> | |
dc29a365 | 14 | #include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */ |
79bf2bb3 | 15 | #include <linux/tick.h> |
01548f4d | 16 | #include <linux/kthread.h> |
734efb46 | 17 | |
c1797baf | 18 | #include "tick-internal.h" |
3a978377 | 19 | #include "timekeeping_internal.h" |
03e13cf5 | 20 | |
7d2f944a TG |
21 | /** |
22 | * clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks | |
23 | * @mult: pointer to mult variable | |
24 | * @shift: pointer to shift variable | |
25 | * @from: frequency to convert from | |
26 | * @to: frequency to convert to | |
5fdade95 | 27 | * @maxsec: guaranteed runtime conversion range in seconds |
7d2f944a TG |
28 | * |
29 | * The function evaluates the shift/mult pair for the scaled math | |
30 | * operations of clocksources and clockevents. | |
31 | * | |
32 | * @to and @from are frequency values in HZ. For clock sources @to is | |
33 | * NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock | |
34 | * event @to is the counter frequency and @from is NSEC_PER_SEC. | |
35 | * | |
5fdade95 | 36 | * The @maxsec conversion range argument controls the time frame in |
7d2f944a TG |
37 | * seconds which must be covered by the runtime conversion with the |
38 | * calculated mult and shift factors. This guarantees that no 64bit | |
39 | * overflow happens when the input value of the conversion is | |
40 | * multiplied with the calculated mult factor. Larger ranges may | |
41 | * reduce the conversion accuracy by chosing smaller mult and shift | |
42 | * factors. | |
43 | */ | |
44 | void | |
5fdade95 | 45 | clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 maxsec) |
7d2f944a TG |
46 | { |
47 | u64 tmp; | |
48 | u32 sft, sftacc= 32; | |
49 | ||
50 | /* | |
51 | * Calculate the shift factor which is limiting the conversion | |
52 | * range: | |
53 | */ | |
5fdade95 | 54 | tmp = ((u64)maxsec * from) >> 32; |
7d2f944a TG |
55 | while (tmp) { |
56 | tmp >>=1; | |
57 | sftacc--; | |
58 | } | |
59 | ||
60 | /* | |
61 | * Find the conversion shift/mult pair which has the best | |
62 | * accuracy and fits the maxsec conversion range: | |
63 | */ | |
64 | for (sft = 32; sft > 0; sft--) { | |
65 | tmp = (u64) to << sft; | |
b5776c4a | 66 | tmp += from / 2; |
7d2f944a TG |
67 | do_div(tmp, from); |
68 | if ((tmp >> sftacc) == 0) | |
69 | break; | |
70 | } | |
71 | *mult = tmp; | |
72 | *shift = sft; | |
73 | } | |
5304121a | 74 | EXPORT_SYMBOL_GPL(clocks_calc_mult_shift); |
7d2f944a | 75 | |
734efb46 JS |
76 | /*[Clocksource internal variables]--------- |
77 | * curr_clocksource: | |
f1b82746 | 78 | * currently selected clocksource. |
39232ed5 BW |
79 | * suspend_clocksource: |
80 | * used to calculate the suspend time. | |
734efb46 JS |
81 | * clocksource_list: |
82 | * linked list with the registered clocksources | |
75c5158f MS |
83 | * clocksource_mutex: |
84 | * protects manipulations to curr_clocksource and the clocksource_list | |
734efb46 JS |
85 | * override_name: |
86 | * Name of the user-specified clocksource. | |
87 | */ | |
f1b82746 | 88 | static struct clocksource *curr_clocksource; |
39232ed5 | 89 | static struct clocksource *suspend_clocksource; |
734efb46 | 90 | static LIST_HEAD(clocksource_list); |
75c5158f | 91 | static DEFINE_MUTEX(clocksource_mutex); |
29b54078 | 92 | static char override_name[CS_NAME_LEN]; |
54a6bc0b | 93 | static int finished_booting; |
39232ed5 | 94 | static u64 suspend_start; |
734efb46 | 95 | |
5d8b34fd | 96 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
f79e0258 | 97 | static void clocksource_watchdog_work(struct work_struct *work); |
332962f2 | 98 | static void clocksource_select(void); |
f79e0258 | 99 | |
5d8b34fd TG |
100 | static LIST_HEAD(watchdog_list); |
101 | static struct clocksource *watchdog; | |
102 | static struct timer_list watchdog_timer; | |
f79e0258 | 103 | static DECLARE_WORK(watchdog_work, clocksource_watchdog_work); |
5d8b34fd | 104 | static DEFINE_SPINLOCK(watchdog_lock); |
fb63a0eb | 105 | static int watchdog_running; |
9fb60336 | 106 | static atomic_t watchdog_reset_pending; |
b52f52a0 | 107 | |
0f48b41f | 108 | static inline void clocksource_watchdog_lock(unsigned long *flags) |
2aae7bcf PZ |
109 | { |
110 | spin_lock_irqsave(&watchdog_lock, *flags); | |
111 | } | |
112 | ||
0f48b41f | 113 | static inline void clocksource_watchdog_unlock(unsigned long *flags) |
2aae7bcf PZ |
114 | { |
115 | spin_unlock_irqrestore(&watchdog_lock, *flags); | |
116 | } | |
117 | ||
e2c631ba PZ |
118 | static int clocksource_watchdog_kthread(void *data); |
119 | static void __clocksource_change_rating(struct clocksource *cs, int rating); | |
120 | ||
5d8b34fd | 121 | /* |
35c35d1a | 122 | * Interval: 0.5sec Threshold: 0.0625s |
5d8b34fd TG |
123 | */ |
124 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
35c35d1a | 125 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) |
5d8b34fd | 126 | |
e2c631ba PZ |
127 | static void clocksource_watchdog_work(struct work_struct *work) |
128 | { | |
129 | /* | |
130 | * We cannot directly run clocksource_watchdog_kthread() here, because | |
131 | * clocksource_select() calls timekeeping_notify() which uses | |
132 | * stop_machine(). One cannot use stop_machine() from a workqueue() due | |
133 | * lock inversions wrt CPU hotplug. | |
134 | * | |
135 | * Also, we only ever run this work once or twice during the lifetime | |
136 | * of the kernel, so there is no point in creating a more permanent | |
137 | * kthread for this. | |
138 | * | |
139 | * If kthread_run fails the next watchdog scan over the | |
140 | * watchdog_list will find the unstable clock again. | |
141 | */ | |
142 | kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog"); | |
143 | } | |
144 | ||
7285dd7f | 145 | static void __clocksource_unstable(struct clocksource *cs) |
5d8b34fd | 146 | { |
5d8b34fd | 147 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); |
c55c87c8 | 148 | cs->flags |= CLOCK_SOURCE_UNSTABLE; |
12907fbb | 149 | |
cd2af07d | 150 | /* |
e2c631ba | 151 | * If the clocksource is registered clocksource_watchdog_kthread() will |
cd2af07d PZ |
152 | * re-rate and re-select. |
153 | */ | |
154 | if (list_empty(&cs->list)) { | |
155 | cs->rating = 0; | |
2aae7bcf | 156 | return; |
cd2af07d | 157 | } |
2aae7bcf | 158 | |
12907fbb TG |
159 | if (cs->mark_unstable) |
160 | cs->mark_unstable(cs); | |
161 | ||
e2c631ba | 162 | /* kick clocksource_watchdog_kthread() */ |
54a6bc0b TG |
163 | if (finished_booting) |
164 | schedule_work(&watchdog_work); | |
5d8b34fd TG |
165 | } |
166 | ||
7285dd7f TG |
167 | /** |
168 | * clocksource_mark_unstable - mark clocksource unstable via watchdog | |
169 | * @cs: clocksource to be marked unstable | |
170 | * | |
7dba33c6 | 171 | * This function is called by the x86 TSC code to mark clocksources as unstable; |
e2c631ba | 172 | * it defers demotion and re-selection to a kthread. |
7285dd7f TG |
173 | */ |
174 | void clocksource_mark_unstable(struct clocksource *cs) | |
175 | { | |
176 | unsigned long flags; | |
177 | ||
178 | spin_lock_irqsave(&watchdog_lock, flags); | |
179 | if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) { | |
2aae7bcf | 180 | if (!list_empty(&cs->list) && list_empty(&cs->wd_list)) |
7285dd7f TG |
181 | list_add(&cs->wd_list, &watchdog_list); |
182 | __clocksource_unstable(cs); | |
183 | } | |
184 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
185 | } | |
186 | ||
e99e88a9 | 187 | static void clocksource_watchdog(struct timer_list *unused) |
5d8b34fd | 188 | { |
c55c87c8 | 189 | struct clocksource *cs; |
a5a1d1c2 | 190 | u64 csnow, wdnow, cslast, wdlast, delta; |
5d8b34fd | 191 | int64_t wd_nsec, cs_nsec; |
9fb60336 | 192 | int next_cpu, reset_pending; |
5d8b34fd TG |
193 | |
194 | spin_lock(&watchdog_lock); | |
fb63a0eb MS |
195 | if (!watchdog_running) |
196 | goto out; | |
5d8b34fd | 197 | |
9fb60336 TG |
198 | reset_pending = atomic_read(&watchdog_reset_pending); |
199 | ||
c55c87c8 MS |
200 | list_for_each_entry(cs, &watchdog_list, wd_list) { |
201 | ||
202 | /* Clocksource already marked unstable? */ | |
01548f4d | 203 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
54a6bc0b TG |
204 | if (finished_booting) |
205 | schedule_work(&watchdog_work); | |
c55c87c8 | 206 | continue; |
01548f4d | 207 | } |
c55c87c8 | 208 | |
b5199515 | 209 | local_irq_disable(); |
8e19608e | 210 | csnow = cs->read(cs); |
b5199515 TG |
211 | wdnow = watchdog->read(watchdog); |
212 | local_irq_enable(); | |
b52f52a0 | 213 | |
8cf4e750 | 214 | /* Clocksource initialized ? */ |
9fb60336 TG |
215 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) || |
216 | atomic_read(&watchdog_reset_pending)) { | |
8cf4e750 | 217 | cs->flags |= CLOCK_SOURCE_WATCHDOG; |
b5199515 TG |
218 | cs->wd_last = wdnow; |
219 | cs->cs_last = csnow; | |
b52f52a0 TG |
220 | continue; |
221 | } | |
222 | ||
3a978377 TG |
223 | delta = clocksource_delta(wdnow, cs->wd_last, watchdog->mask); |
224 | wd_nsec = clocksource_cyc2ns(delta, watchdog->mult, | |
225 | watchdog->shift); | |
b5199515 | 226 | |
3a978377 TG |
227 | delta = clocksource_delta(csnow, cs->cs_last, cs->mask); |
228 | cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift); | |
0b046b21 JS |
229 | wdlast = cs->wd_last; /* save these in case we print them */ |
230 | cslast = cs->cs_last; | |
b5199515 TG |
231 | cs->cs_last = csnow; |
232 | cs->wd_last = wdnow; | |
233 | ||
9fb60336 TG |
234 | if (atomic_read(&watchdog_reset_pending)) |
235 | continue; | |
236 | ||
b5199515 | 237 | /* Check the deviation from the watchdog clocksource. */ |
79211c8e | 238 | if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) { |
390dd67c SI |
239 | pr_warn("timekeeping watchdog on CPU%d: Marking clocksource '%s' as unstable because the skew is too large:\n", |
240 | smp_processor_id(), cs->name); | |
45bbfe64 | 241 | pr_warn(" '%s' wd_now: %llx wd_last: %llx mask: %llx\n", |
0b046b21 | 242 | watchdog->name, wdnow, wdlast, watchdog->mask); |
45bbfe64 | 243 | pr_warn(" '%s' cs_now: %llx cs_last: %llx mask: %llx\n", |
0b046b21 JS |
244 | cs->name, csnow, cslast, cs->mask); |
245 | __clocksource_unstable(cs); | |
8cf4e750 MS |
246 | continue; |
247 | } | |
248 | ||
b421b22b PZ |
249 | if (cs == curr_clocksource && cs->tick_stable) |
250 | cs->tick_stable(cs); | |
251 | ||
8cf4e750 MS |
252 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && |
253 | (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
254 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
332962f2 | 255 | /* Mark it valid for high-res. */ |
8cf4e750 | 256 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
332962f2 TG |
257 | |
258 | /* | |
259 | * clocksource_done_booting() will sort it if | |
260 | * finished_booting is not set yet. | |
261 | */ | |
262 | if (!finished_booting) | |
263 | continue; | |
264 | ||
8cf4e750 | 265 | /* |
332962f2 TG |
266 | * If this is not the current clocksource let |
267 | * the watchdog thread reselect it. Due to the | |
268 | * change to high res this clocksource might | |
269 | * be preferred now. If it is the current | |
270 | * clocksource let the tick code know about | |
271 | * that change. | |
8cf4e750 | 272 | */ |
332962f2 TG |
273 | if (cs != curr_clocksource) { |
274 | cs->flags |= CLOCK_SOURCE_RESELECT; | |
275 | schedule_work(&watchdog_work); | |
276 | } else { | |
277 | tick_clock_notify(); | |
278 | } | |
5d8b34fd TG |
279 | } |
280 | } | |
281 | ||
9fb60336 TG |
282 | /* |
283 | * We only clear the watchdog_reset_pending, when we did a | |
284 | * full cycle through all clocksources. | |
285 | */ | |
286 | if (reset_pending) | |
287 | atomic_dec(&watchdog_reset_pending); | |
288 | ||
c55c87c8 MS |
289 | /* |
290 | * Cycle through CPUs to check if the CPUs stay synchronized | |
291 | * to each other. | |
292 | */ | |
293 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); | |
294 | if (next_cpu >= nr_cpu_ids) | |
295 | next_cpu = cpumask_first(cpu_online_mask); | |
febac332 KK |
296 | |
297 | /* | |
298 | * Arm timer if not already pending: could race with concurrent | |
299 | * pair clocksource_stop_watchdog() clocksource_start_watchdog(). | |
300 | */ | |
301 | if (!timer_pending(&watchdog_timer)) { | |
302 | watchdog_timer.expires += WATCHDOG_INTERVAL; | |
303 | add_timer_on(&watchdog_timer, next_cpu); | |
304 | } | |
fb63a0eb | 305 | out: |
5d8b34fd TG |
306 | spin_unlock(&watchdog_lock); |
307 | } | |
0f8e8ef7 | 308 | |
fb63a0eb MS |
309 | static inline void clocksource_start_watchdog(void) |
310 | { | |
311 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) | |
312 | return; | |
e99e88a9 | 313 | timer_setup(&watchdog_timer, clocksource_watchdog, 0); |
fb63a0eb MS |
314 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; |
315 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); | |
316 | watchdog_running = 1; | |
317 | } | |
318 | ||
319 | static inline void clocksource_stop_watchdog(void) | |
320 | { | |
321 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) | |
322 | return; | |
323 | del_timer(&watchdog_timer); | |
324 | watchdog_running = 0; | |
325 | } | |
326 | ||
0f8e8ef7 MS |
327 | static inline void clocksource_reset_watchdog(void) |
328 | { | |
329 | struct clocksource *cs; | |
330 | ||
331 | list_for_each_entry(cs, &watchdog_list, wd_list) | |
332 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
333 | } | |
334 | ||
b52f52a0 TG |
335 | static void clocksource_resume_watchdog(void) |
336 | { | |
9fb60336 | 337 | atomic_inc(&watchdog_reset_pending); |
b52f52a0 TG |
338 | } |
339 | ||
fb63a0eb | 340 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
5d8b34fd | 341 | { |
5b9e886a PZ |
342 | INIT_LIST_HEAD(&cs->wd_list); |
343 | ||
5d8b34fd | 344 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { |
fb63a0eb | 345 | /* cs is a clocksource to be watched. */ |
5d8b34fd | 346 | list_add(&cs->wd_list, &watchdog_list); |
fb63a0eb | 347 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
948ac6d7 | 348 | } else { |
fb63a0eb | 349 | /* cs is a watchdog. */ |
948ac6d7 | 350 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
5d8b34fd | 351 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
bbf66d89 | 352 | } |
bbf66d89 VK |
353 | } |
354 | ||
355 | static void clocksource_select_watchdog(bool fallback) | |
356 | { | |
357 | struct clocksource *cs, *old_wd; | |
358 | unsigned long flags; | |
359 | ||
360 | spin_lock_irqsave(&watchdog_lock, flags); | |
361 | /* save current watchdog */ | |
362 | old_wd = watchdog; | |
363 | if (fallback) | |
364 | watchdog = NULL; | |
365 | ||
366 | list_for_each_entry(cs, &clocksource_list, list) { | |
367 | /* cs is a clocksource to be watched. */ | |
368 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) | |
369 | continue; | |
370 | ||
371 | /* Skip current if we were requested for a fallback. */ | |
372 | if (fallback && cs == old_wd) | |
373 | continue; | |
374 | ||
fb63a0eb | 375 | /* Pick the best watchdog. */ |
bbf66d89 | 376 | if (!watchdog || cs->rating > watchdog->rating) |
5d8b34fd | 377 | watchdog = cs; |
5d8b34fd | 378 | } |
bbf66d89 VK |
379 | /* If we failed to find a fallback restore the old one. */ |
380 | if (!watchdog) | |
381 | watchdog = old_wd; | |
382 | ||
383 | /* If we changed the watchdog we need to reset cycles. */ | |
384 | if (watchdog != old_wd) | |
385 | clocksource_reset_watchdog(); | |
386 | ||
fb63a0eb MS |
387 | /* Check if the watchdog timer needs to be started. */ |
388 | clocksource_start_watchdog(); | |
5d8b34fd TG |
389 | spin_unlock_irqrestore(&watchdog_lock, flags); |
390 | } | |
fb63a0eb MS |
391 | |
392 | static void clocksource_dequeue_watchdog(struct clocksource *cs) | |
393 | { | |
a89c7edb TG |
394 | if (cs != watchdog) { |
395 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
396 | /* cs is a watched clocksource. */ | |
397 | list_del_init(&cs->wd_list); | |
398 | /* Check if the watchdog timer needs to be stopped. */ | |
399 | clocksource_stop_watchdog(); | |
fb63a0eb MS |
400 | } |
401 | } | |
fb63a0eb MS |
402 | } |
403 | ||
e2c631ba | 404 | static int __clocksource_watchdog_kthread(void) |
c55c87c8 MS |
405 | { |
406 | struct clocksource *cs, *tmp; | |
407 | unsigned long flags; | |
332962f2 | 408 | int select = 0; |
c55c87c8 MS |
409 | |
410 | spin_lock_irqsave(&watchdog_lock, flags); | |
332962f2 | 411 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { |
c55c87c8 MS |
412 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
413 | list_del_init(&cs->wd_list); | |
2aae7bcf | 414 | __clocksource_change_rating(cs, 0); |
332962f2 TG |
415 | select = 1; |
416 | } | |
417 | if (cs->flags & CLOCK_SOURCE_RESELECT) { | |
418 | cs->flags &= ~CLOCK_SOURCE_RESELECT; | |
419 | select = 1; | |
c55c87c8 | 420 | } |
332962f2 | 421 | } |
c55c87c8 MS |
422 | /* Check if the watchdog timer needs to be stopped. */ |
423 | clocksource_stop_watchdog(); | |
6ea41d25 TG |
424 | spin_unlock_irqrestore(&watchdog_lock, flags); |
425 | ||
332962f2 TG |
426 | return select; |
427 | } | |
428 | ||
e2c631ba | 429 | static int clocksource_watchdog_kthread(void *data) |
332962f2 TG |
430 | { |
431 | mutex_lock(&clocksource_mutex); | |
e2c631ba | 432 | if (__clocksource_watchdog_kthread()) |
332962f2 | 433 | clocksource_select(); |
d0981a1b | 434 | mutex_unlock(&clocksource_mutex); |
e2c631ba | 435 | return 0; |
c55c87c8 MS |
436 | } |
437 | ||
7eaeb343 TG |
438 | static bool clocksource_is_watchdog(struct clocksource *cs) |
439 | { | |
440 | return cs == watchdog; | |
441 | } | |
442 | ||
fb63a0eb MS |
443 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
444 | ||
445 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
5d8b34fd TG |
446 | { |
447 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
448 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
449 | } | |
b52f52a0 | 450 | |
bbf66d89 | 451 | static void clocksource_select_watchdog(bool fallback) { } |
fb63a0eb | 452 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
b52f52a0 | 453 | static inline void clocksource_resume_watchdog(void) { } |
e2c631ba | 454 | static inline int __clocksource_watchdog_kthread(void) { return 0; } |
7eaeb343 | 455 | static bool clocksource_is_watchdog(struct clocksource *cs) { return false; } |
397bbf6d | 456 | void clocksource_mark_unstable(struct clocksource *cs) { } |
fb63a0eb | 457 | |
db6f9e55 MM |
458 | static inline void clocksource_watchdog_lock(unsigned long *flags) { } |
459 | static inline void clocksource_watchdog_unlock(unsigned long *flags) { } | |
2aae7bcf | 460 | |
fb63a0eb | 461 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
5d8b34fd | 462 | |
39232ed5 BW |
463 | static bool clocksource_is_suspend(struct clocksource *cs) |
464 | { | |
465 | return cs == suspend_clocksource; | |
466 | } | |
467 | ||
468 | static void __clocksource_suspend_select(struct clocksource *cs) | |
469 | { | |
470 | /* | |
471 | * Skip the clocksource which will be stopped in suspend state. | |
472 | */ | |
473 | if (!(cs->flags & CLOCK_SOURCE_SUSPEND_NONSTOP)) | |
474 | return; | |
475 | ||
476 | /* | |
477 | * The nonstop clocksource can be selected as the suspend clocksource to | |
478 | * calculate the suspend time, so it should not supply suspend/resume | |
479 | * interfaces to suspend the nonstop clocksource when system suspends. | |
480 | */ | |
481 | if (cs->suspend || cs->resume) { | |
482 | pr_warn("Nonstop clocksource %s should not supply suspend/resume interfaces\n", | |
483 | cs->name); | |
484 | } | |
485 | ||
486 | /* Pick the best rating. */ | |
487 | if (!suspend_clocksource || cs->rating > suspend_clocksource->rating) | |
488 | suspend_clocksource = cs; | |
489 | } | |
490 | ||
491 | /** | |
492 | * clocksource_suspend_select - Select the best clocksource for suspend timing | |
493 | * @fallback: if select a fallback clocksource | |
494 | */ | |
495 | static void clocksource_suspend_select(bool fallback) | |
496 | { | |
497 | struct clocksource *cs, *old_suspend; | |
498 | ||
499 | old_suspend = suspend_clocksource; | |
500 | if (fallback) | |
501 | suspend_clocksource = NULL; | |
502 | ||
503 | list_for_each_entry(cs, &clocksource_list, list) { | |
504 | /* Skip current if we were requested for a fallback. */ | |
505 | if (fallback && cs == old_suspend) | |
506 | continue; | |
507 | ||
508 | __clocksource_suspend_select(cs); | |
509 | } | |
510 | } | |
511 | ||
512 | /** | |
513 | * clocksource_start_suspend_timing - Start measuring the suspend timing | |
514 | * @cs: current clocksource from timekeeping | |
515 | * @start_cycles: current cycles from timekeeping | |
516 | * | |
517 | * This function will save the start cycle values of suspend timer to calculate | |
518 | * the suspend time when resuming system. | |
519 | * | |
520 | * This function is called late in the suspend process from timekeeping_suspend(), | |
521 | * that means processes are freezed, non-boot cpus and interrupts are disabled | |
522 | * now. It is therefore possible to start the suspend timer without taking the | |
523 | * clocksource mutex. | |
524 | */ | |
525 | void clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles) | |
526 | { | |
527 | if (!suspend_clocksource) | |
528 | return; | |
529 | ||
530 | /* | |
531 | * If current clocksource is the suspend timer, we should use the | |
532 | * tkr_mono.cycle_last value as suspend_start to avoid same reading | |
533 | * from suspend timer. | |
534 | */ | |
535 | if (clocksource_is_suspend(cs)) { | |
536 | suspend_start = start_cycles; | |
537 | return; | |
538 | } | |
539 | ||
540 | if (suspend_clocksource->enable && | |
541 | suspend_clocksource->enable(suspend_clocksource)) { | |
542 | pr_warn_once("Failed to enable the non-suspend-able clocksource.\n"); | |
543 | return; | |
544 | } | |
545 | ||
546 | suspend_start = suspend_clocksource->read(suspend_clocksource); | |
547 | } | |
548 | ||
549 | /** | |
550 | * clocksource_stop_suspend_timing - Stop measuring the suspend timing | |
551 | * @cs: current clocksource from timekeeping | |
552 | * @cycle_now: current cycles from timekeeping | |
553 | * | |
554 | * This function will calculate the suspend time from suspend timer. | |
555 | * | |
556 | * Returns nanoseconds since suspend started, 0 if no usable suspend clocksource. | |
557 | * | |
558 | * This function is called early in the resume process from timekeeping_resume(), | |
559 | * that means there is only one cpu, no processes are running and the interrupts | |
560 | * are disabled. It is therefore possible to stop the suspend timer without | |
561 | * taking the clocksource mutex. | |
562 | */ | |
563 | u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 cycle_now) | |
564 | { | |
565 | u64 now, delta, nsec = 0; | |
566 | ||
567 | if (!suspend_clocksource) | |
568 | return 0; | |
569 | ||
570 | /* | |
571 | * If current clocksource is the suspend timer, we should use the | |
572 | * tkr_mono.cycle_last value from timekeeping as current cycle to | |
573 | * avoid same reading from suspend timer. | |
574 | */ | |
575 | if (clocksource_is_suspend(cs)) | |
576 | now = cycle_now; | |
577 | else | |
578 | now = suspend_clocksource->read(suspend_clocksource); | |
579 | ||
580 | if (now > suspend_start) { | |
581 | delta = clocksource_delta(now, suspend_start, | |
582 | suspend_clocksource->mask); | |
583 | nsec = mul_u64_u32_shr(delta, suspend_clocksource->mult, | |
584 | suspend_clocksource->shift); | |
585 | } | |
586 | ||
587 | /* | |
588 | * Disable the suspend timer to save power if current clocksource is | |
589 | * not the suspend timer. | |
590 | */ | |
591 | if (!clocksource_is_suspend(cs) && suspend_clocksource->disable) | |
592 | suspend_clocksource->disable(suspend_clocksource); | |
593 | ||
594 | return nsec; | |
595 | } | |
596 | ||
c54a42b1 MD |
597 | /** |
598 | * clocksource_suspend - suspend the clocksource(s) | |
599 | */ | |
600 | void clocksource_suspend(void) | |
601 | { | |
602 | struct clocksource *cs; | |
603 | ||
604 | list_for_each_entry_reverse(cs, &clocksource_list, list) | |
605 | if (cs->suspend) | |
606 | cs->suspend(cs); | |
607 | } | |
608 | ||
b52f52a0 TG |
609 | /** |
610 | * clocksource_resume - resume the clocksource(s) | |
611 | */ | |
612 | void clocksource_resume(void) | |
613 | { | |
2e197586 | 614 | struct clocksource *cs; |
b52f52a0 | 615 | |
75c5158f | 616 | list_for_each_entry(cs, &clocksource_list, list) |
b52f52a0 | 617 | if (cs->resume) |
17622339 | 618 | cs->resume(cs); |
b52f52a0 TG |
619 | |
620 | clocksource_resume_watchdog(); | |
b52f52a0 TG |
621 | } |
622 | ||
7c3078b6 JW |
623 | /** |
624 | * clocksource_touch_watchdog - Update watchdog | |
625 | * | |
626 | * Update the watchdog after exception contexts such as kgdb so as not | |
7b7422a5 TG |
627 | * to incorrectly trip the watchdog. This might fail when the kernel |
628 | * was stopped in code which holds watchdog_lock. | |
7c3078b6 JW |
629 | */ |
630 | void clocksource_touch_watchdog(void) | |
631 | { | |
632 | clocksource_resume_watchdog(); | |
633 | } | |
634 | ||
d65670a7 JS |
635 | /** |
636 | * clocksource_max_adjustment- Returns max adjustment amount | |
637 | * @cs: Pointer to clocksource | |
638 | * | |
639 | */ | |
640 | static u32 clocksource_max_adjustment(struct clocksource *cs) | |
641 | { | |
642 | u64 ret; | |
643 | /* | |
88b28adf | 644 | * We won't try to correct for more than 11% adjustments (110,000 ppm), |
d65670a7 JS |
645 | */ |
646 | ret = (u64)cs->mult * 11; | |
647 | do_div(ret,100); | |
648 | return (u32)ret; | |
649 | } | |
650 | ||
98962465 | 651 | /** |
87d8b9eb SB |
652 | * clocks_calc_max_nsecs - Returns maximum nanoseconds that can be converted |
653 | * @mult: cycle to nanosecond multiplier | |
654 | * @shift: cycle to nanosecond divisor (power of two) | |
655 | * @maxadj: maximum adjustment value to mult (~11%) | |
656 | * @mask: bitmask for two's complement subtraction of non 64 bit counters | |
fb82fe2f JS |
657 | * @max_cyc: maximum cycle value before potential overflow (does not include |
658 | * any safety margin) | |
362fde04 | 659 | * |
8e56f33f JS |
660 | * NOTE: This function includes a safety margin of 50%, in other words, we |
661 | * return half the number of nanoseconds the hardware counter can technically | |
662 | * cover. This is done so that we can potentially detect problems caused by | |
663 | * delayed timers or bad hardware, which might result in time intervals that | |
571af55a | 664 | * are larger than what the math used can handle without overflows. |
98962465 | 665 | */ |
fb82fe2f | 666 | u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cyc) |
98962465 JH |
667 | { |
668 | u64 max_nsecs, max_cycles; | |
669 | ||
670 | /* | |
671 | * Calculate the maximum number of cycles that we can pass to the | |
6086e346 | 672 | * cyc2ns() function without overflowing a 64-bit result. |
98962465 | 673 | */ |
6086e346 JS |
674 | max_cycles = ULLONG_MAX; |
675 | do_div(max_cycles, mult+maxadj); | |
98962465 JH |
676 | |
677 | /* | |
678 | * The actual maximum number of cycles we can defer the clocksource is | |
87d8b9eb | 679 | * determined by the minimum of max_cycles and mask. |
d65670a7 JS |
680 | * Note: Here we subtract the maxadj to make sure we don't sleep for |
681 | * too long if there's a large negative adjustment. | |
98962465 | 682 | */ |
87d8b9eb SB |
683 | max_cycles = min(max_cycles, mask); |
684 | max_nsecs = clocksource_cyc2ns(max_cycles, mult - maxadj, shift); | |
685 | ||
fb82fe2f JS |
686 | /* return the max_cycles value as well if requested */ |
687 | if (max_cyc) | |
688 | *max_cyc = max_cycles; | |
689 | ||
362fde04 JS |
690 | /* Return 50% of the actual maximum, so we can detect bad values */ |
691 | max_nsecs >>= 1; | |
692 | ||
87d8b9eb SB |
693 | return max_nsecs; |
694 | } | |
695 | ||
696 | /** | |
fb82fe2f JS |
697 | * clocksource_update_max_deferment - Updates the clocksource max_idle_ns & max_cycles |
698 | * @cs: Pointer to clocksource to be updated | |
87d8b9eb SB |
699 | * |
700 | */ | |
fb82fe2f | 701 | static inline void clocksource_update_max_deferment(struct clocksource *cs) |
87d8b9eb | 702 | { |
fb82fe2f JS |
703 | cs->max_idle_ns = clocks_calc_max_nsecs(cs->mult, cs->shift, |
704 | cs->maxadj, cs->mask, | |
705 | &cs->max_cycles); | |
98962465 JH |
706 | } |
707 | ||
592913ec | 708 | #ifndef CONFIG_ARCH_USES_GETTIMEOFFSET |
734efb46 | 709 | |
f5a2e343 | 710 | static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur) |
5d33b883 TG |
711 | { |
712 | struct clocksource *cs; | |
713 | ||
714 | if (!finished_booting || list_empty(&clocksource_list)) | |
715 | return NULL; | |
716 | ||
717 | /* | |
718 | * We pick the clocksource with the highest rating. If oneshot | |
719 | * mode is active, we pick the highres valid clocksource with | |
720 | * the best rating. | |
721 | */ | |
722 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
723 | if (skipcur && cs == curr_clocksource) |
724 | continue; | |
5d33b883 TG |
725 | if (oneshot && !(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES)) |
726 | continue; | |
727 | return cs; | |
728 | } | |
729 | return NULL; | |
730 | } | |
731 | ||
f5a2e343 | 732 | static void __clocksource_select(bool skipcur) |
734efb46 | 733 | { |
5d33b883 | 734 | bool oneshot = tick_oneshot_mode_active(); |
f1b82746 | 735 | struct clocksource *best, *cs; |
5d8b34fd | 736 | |
5d33b883 | 737 | /* Find the best suitable clocksource */ |
f5a2e343 | 738 | best = clocksource_find_best(oneshot, skipcur); |
5d33b883 | 739 | if (!best) |
f1b82746 | 740 | return; |
5d33b883 | 741 | |
7f852afe BW |
742 | if (!strlen(override_name)) |
743 | goto found; | |
744 | ||
f1b82746 MS |
745 | /* Check for the override clocksource. */ |
746 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
747 | if (skipcur && cs == curr_clocksource) |
748 | continue; | |
f1b82746 MS |
749 | if (strcmp(cs->name, override_name) != 0) |
750 | continue; | |
751 | /* | |
752 | * Check to make sure we don't switch to a non-highres | |
753 | * capable clocksource if the tick code is in oneshot | |
754 | * mode (highres or nohz) | |
755 | */ | |
5d33b883 | 756 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && oneshot) { |
f1b82746 | 757 | /* Override clocksource cannot be used. */ |
36374583 KW |
758 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
759 | pr_warn("Override clocksource %s is unstable and not HRT compatible - cannot switch while in HRT/NOHZ mode\n", | |
760 | cs->name); | |
761 | override_name[0] = 0; | |
762 | } else { | |
763 | /* | |
764 | * The override cannot be currently verified. | |
765 | * Deferring to let the watchdog check. | |
766 | */ | |
767 | pr_info("Override clocksource %s is not currently HRT compatible - deferring\n", | |
768 | cs->name); | |
769 | } | |
f1b82746 MS |
770 | } else |
771 | /* Override clocksource can be used. */ | |
772 | best = cs; | |
773 | break; | |
774 | } | |
ba919d1c | 775 | |
7f852afe | 776 | found: |
ba919d1c TG |
777 | if (curr_clocksource != best && !timekeeping_notify(best)) { |
778 | pr_info("Switched to clocksource %s\n", best->name); | |
75c5158f | 779 | curr_clocksource = best; |
75c5158f | 780 | } |
f1b82746 | 781 | } |
734efb46 | 782 | |
f5a2e343 TG |
783 | /** |
784 | * clocksource_select - Select the best clocksource available | |
785 | * | |
786 | * Private function. Must hold clocksource_mutex when called. | |
787 | * | |
788 | * Select the clocksource with the best rating, or the clocksource, | |
789 | * which is selected by userspace override. | |
790 | */ | |
791 | static void clocksource_select(void) | |
792 | { | |
cfed432d | 793 | __clocksource_select(false); |
f5a2e343 TG |
794 | } |
795 | ||
7eaeb343 TG |
796 | static void clocksource_select_fallback(void) |
797 | { | |
cfed432d | 798 | __clocksource_select(true); |
7eaeb343 TG |
799 | } |
800 | ||
592913ec | 801 | #else /* !CONFIG_ARCH_USES_GETTIMEOFFSET */ |
54a6bc0b | 802 | static inline void clocksource_select(void) { } |
1eaff672 | 803 | static inline void clocksource_select_fallback(void) { } |
54a6bc0b TG |
804 | |
805 | #endif | |
806 | ||
75c5158f MS |
807 | /* |
808 | * clocksource_done_booting - Called near the end of core bootup | |
809 | * | |
810 | * Hack to avoid lots of clocksource churn at boot time. | |
811 | * We use fs_initcall because we want this to start before | |
812 | * device_initcall but after subsys_initcall. | |
813 | */ | |
814 | static int __init clocksource_done_booting(void) | |
815 | { | |
ad6759fb JS |
816 | mutex_lock(&clocksource_mutex); |
817 | curr_clocksource = clocksource_default_clock(); | |
75c5158f | 818 | finished_booting = 1; |
54a6bc0b TG |
819 | /* |
820 | * Run the watchdog first to eliminate unstable clock sources | |
821 | */ | |
e2c631ba | 822 | __clocksource_watchdog_kthread(); |
75c5158f | 823 | clocksource_select(); |
e6c73305 | 824 | mutex_unlock(&clocksource_mutex); |
75c5158f MS |
825 | return 0; |
826 | } | |
827 | fs_initcall(clocksource_done_booting); | |
828 | ||
92c7e002 TG |
829 | /* |
830 | * Enqueue the clocksource sorted by rating | |
734efb46 | 831 | */ |
f1b82746 | 832 | static void clocksource_enqueue(struct clocksource *cs) |
734efb46 | 833 | { |
f1b82746 MS |
834 | struct list_head *entry = &clocksource_list; |
835 | struct clocksource *tmp; | |
92c7e002 | 836 | |
0fb71d34 | 837 | list_for_each_entry(tmp, &clocksource_list, list) { |
92c7e002 | 838 | /* Keep track of the place, where to insert */ |
0fb71d34 MH |
839 | if (tmp->rating < cs->rating) |
840 | break; | |
841 | entry = &tmp->list; | |
842 | } | |
f1b82746 | 843 | list_add(&cs->list, entry); |
734efb46 JS |
844 | } |
845 | ||
d7e81c26 | 846 | /** |
fba9e072 | 847 | * __clocksource_update_freq_scale - Used update clocksource with new freq |
b1b73d09 | 848 | * @cs: clocksource to be registered |
d7e81c26 JS |
849 | * @scale: Scale factor multiplied against freq to get clocksource hz |
850 | * @freq: clocksource frequency (cycles per second) divided by scale | |
851 | * | |
852db46d | 852 | * This should only be called from the clocksource->enable() method. |
d7e81c26 JS |
853 | * |
854 | * This *SHOULD NOT* be called directly! Please use the | |
fba9e072 JS |
855 | * __clocksource_update_freq_hz() or __clocksource_update_freq_khz() helper |
856 | * functions. | |
d7e81c26 | 857 | */ |
fba9e072 | 858 | void __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq) |
d7e81c26 | 859 | { |
c0e299b1 | 860 | u64 sec; |
f8935983 | 861 | |
d7e81c26 | 862 | /* |
f8935983 JS |
863 | * Default clocksources are *special* and self-define their mult/shift. |
864 | * But, you're not special, so you should specify a freq value. | |
d7e81c26 | 865 | */ |
f8935983 JS |
866 | if (freq) { |
867 | /* | |
868 | * Calc the maximum number of seconds which we can run before | |
869 | * wrapping around. For clocksources which have a mask > 32-bit | |
870 | * we need to limit the max sleep time to have a good | |
871 | * conversion precision. 10 minutes is still a reasonable | |
872 | * amount. That results in a shift value of 24 for a | |
873 | * clocksource with mask >= 40-bit and f >= 4GHz. That maps to | |
874 | * ~ 0.06ppm granularity for NTP. | |
875 | */ | |
876 | sec = cs->mask; | |
877 | do_div(sec, freq); | |
878 | do_div(sec, scale); | |
879 | if (!sec) | |
880 | sec = 1; | |
881 | else if (sec > 600 && cs->mask > UINT_MAX) | |
882 | sec = 600; | |
883 | ||
884 | clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, | |
885 | NSEC_PER_SEC / scale, sec * scale); | |
886 | } | |
d65670a7 | 887 | /* |
362fde04 JS |
888 | * Ensure clocksources that have large 'mult' values don't overflow |
889 | * when adjusted. | |
d65670a7 JS |
890 | */ |
891 | cs->maxadj = clocksource_max_adjustment(cs); | |
f8935983 JS |
892 | while (freq && ((cs->mult + cs->maxadj < cs->mult) |
893 | || (cs->mult - cs->maxadj > cs->mult))) { | |
d65670a7 JS |
894 | cs->mult >>= 1; |
895 | cs->shift--; | |
896 | cs->maxadj = clocksource_max_adjustment(cs); | |
897 | } | |
898 | ||
f8935983 JS |
899 | /* |
900 | * Only warn for *special* clocksources that self-define | |
901 | * their mult/shift values and don't specify a freq. | |
902 | */ | |
903 | WARN_ONCE(cs->mult + cs->maxadj < cs->mult, | |
904 | "timekeeping: Clocksource %s might overflow on 11%% adjustment\n", | |
905 | cs->name); | |
906 | ||
fb82fe2f | 907 | clocksource_update_max_deferment(cs); |
8cc8c525 | 908 | |
45bbfe64 JP |
909 | pr_info("%s: mask: 0x%llx max_cycles: 0x%llx, max_idle_ns: %lld ns\n", |
910 | cs->name, cs->mask, cs->max_cycles, cs->max_idle_ns); | |
852db46d | 911 | } |
fba9e072 | 912 | EXPORT_SYMBOL_GPL(__clocksource_update_freq_scale); |
852db46d JS |
913 | |
914 | /** | |
915 | * __clocksource_register_scale - Used to install new clocksources | |
b1b73d09 | 916 | * @cs: clocksource to be registered |
852db46d JS |
917 | * @scale: Scale factor multiplied against freq to get clocksource hz |
918 | * @freq: clocksource frequency (cycles per second) divided by scale | |
919 | * | |
920 | * Returns -EBUSY if registration fails, zero otherwise. | |
921 | * | |
922 | * This *SHOULD NOT* be called directly! Please use the | |
923 | * clocksource_register_hz() or clocksource_register_khz helper functions. | |
924 | */ | |
925 | int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) | |
926 | { | |
2aae7bcf | 927 | unsigned long flags; |
852db46d | 928 | |
d67f34c1 TG |
929 | clocksource_arch_init(cs); |
930 | ||
5d51bee7 TG |
931 | #ifdef CONFIG_GENERIC_VDSO_CLOCK_MODE |
932 | if (cs->vdso_clock_mode < 0 || | |
933 | cs->vdso_clock_mode >= VDSO_CLOCKMODE_MAX) { | |
934 | pr_warn("clocksource %s registered with invalid VDSO mode %d. Disabling VDSO support.\n", | |
935 | cs->name, cs->vdso_clock_mode); | |
936 | cs->vdso_clock_mode = VDSO_CLOCKMODE_NONE; | |
937 | } | |
938 | #endif | |
939 | ||
b595076a | 940 | /* Initialize mult/shift and max_idle_ns */ |
fba9e072 | 941 | __clocksource_update_freq_scale(cs, scale, freq); |
d7e81c26 | 942 | |
be278e98 | 943 | /* Add clocksource to the clocksource list */ |
d7e81c26 | 944 | mutex_lock(&clocksource_mutex); |
2aae7bcf PZ |
945 | |
946 | clocksource_watchdog_lock(&flags); | |
d7e81c26 | 947 | clocksource_enqueue(cs); |
d7e81c26 | 948 | clocksource_enqueue_watchdog(cs); |
2aae7bcf PZ |
949 | clocksource_watchdog_unlock(&flags); |
950 | ||
e05b2efb | 951 | clocksource_select(); |
bbf66d89 | 952 | clocksource_select_watchdog(false); |
39232ed5 | 953 | __clocksource_suspend_select(cs); |
d7e81c26 JS |
954 | mutex_unlock(&clocksource_mutex); |
955 | return 0; | |
956 | } | |
957 | EXPORT_SYMBOL_GPL(__clocksource_register_scale); | |
958 | ||
d0981a1b TG |
959 | static void __clocksource_change_rating(struct clocksource *cs, int rating) |
960 | { | |
961 | list_del(&cs->list); | |
962 | cs->rating = rating; | |
963 | clocksource_enqueue(cs); | |
d0981a1b TG |
964 | } |
965 | ||
734efb46 | 966 | /** |
92c7e002 | 967 | * clocksource_change_rating - Change the rating of a registered clocksource |
b1b73d09 KK |
968 | * @cs: clocksource to be changed |
969 | * @rating: new rating | |
734efb46 | 970 | */ |
92c7e002 | 971 | void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb46 | 972 | { |
2aae7bcf PZ |
973 | unsigned long flags; |
974 | ||
75c5158f | 975 | mutex_lock(&clocksource_mutex); |
2aae7bcf | 976 | clocksource_watchdog_lock(&flags); |
d0981a1b | 977 | __clocksource_change_rating(cs, rating); |
2aae7bcf PZ |
978 | clocksource_watchdog_unlock(&flags); |
979 | ||
332962f2 | 980 | clocksource_select(); |
bbf66d89 | 981 | clocksource_select_watchdog(false); |
39232ed5 | 982 | clocksource_suspend_select(false); |
75c5158f | 983 | mutex_unlock(&clocksource_mutex); |
734efb46 | 984 | } |
fb63a0eb | 985 | EXPORT_SYMBOL(clocksource_change_rating); |
734efb46 | 986 | |
7eaeb343 TG |
987 | /* |
988 | * Unbind clocksource @cs. Called with clocksource_mutex held | |
989 | */ | |
990 | static int clocksource_unbind(struct clocksource *cs) | |
991 | { | |
2aae7bcf PZ |
992 | unsigned long flags; |
993 | ||
bbf66d89 VK |
994 | if (clocksource_is_watchdog(cs)) { |
995 | /* Select and try to install a replacement watchdog. */ | |
996 | clocksource_select_watchdog(true); | |
997 | if (clocksource_is_watchdog(cs)) | |
998 | return -EBUSY; | |
999 | } | |
7eaeb343 TG |
1000 | |
1001 | if (cs == curr_clocksource) { | |
1002 | /* Select and try to install a replacement clock source */ | |
1003 | clocksource_select_fallback(); | |
1004 | if (curr_clocksource == cs) | |
1005 | return -EBUSY; | |
1006 | } | |
2aae7bcf | 1007 | |
39232ed5 BW |
1008 | if (clocksource_is_suspend(cs)) { |
1009 | /* | |
1010 | * Select and try to install a replacement suspend clocksource. | |
1011 | * If no replacement suspend clocksource, we will just let the | |
1012 | * clocksource go and have no suspend clocksource. | |
1013 | */ | |
1014 | clocksource_suspend_select(true); | |
1015 | } | |
1016 | ||
2aae7bcf | 1017 | clocksource_watchdog_lock(&flags); |
7eaeb343 TG |
1018 | clocksource_dequeue_watchdog(cs); |
1019 | list_del_init(&cs->list); | |
2aae7bcf PZ |
1020 | clocksource_watchdog_unlock(&flags); |
1021 | ||
7eaeb343 TG |
1022 | return 0; |
1023 | } | |
1024 | ||
4713e22c TG |
1025 | /** |
1026 | * clocksource_unregister - remove a registered clocksource | |
b1b73d09 | 1027 | * @cs: clocksource to be unregistered |
4713e22c | 1028 | */ |
a89c7edb | 1029 | int clocksource_unregister(struct clocksource *cs) |
4713e22c | 1030 | { |
a89c7edb TG |
1031 | int ret = 0; |
1032 | ||
75c5158f | 1033 | mutex_lock(&clocksource_mutex); |
a89c7edb TG |
1034 | if (!list_empty(&cs->list)) |
1035 | ret = clocksource_unbind(cs); | |
75c5158f | 1036 | mutex_unlock(&clocksource_mutex); |
a89c7edb | 1037 | return ret; |
4713e22c | 1038 | } |
fb63a0eb | 1039 | EXPORT_SYMBOL(clocksource_unregister); |
4713e22c | 1040 | |
2b013700 | 1041 | #ifdef CONFIG_SYSFS |
734efb46 | 1042 | /** |
e87821d1 | 1043 | * current_clocksource_show - sysfs interface for current clocksource |
734efb46 | 1044 | * @dev: unused |
b1b73d09 | 1045 | * @attr: unused |
734efb46 JS |
1046 | * @buf: char buffer to be filled with clocksource list |
1047 | * | |
1048 | * Provides sysfs interface for listing current clocksource. | |
1049 | */ | |
e87821d1 BW |
1050 | static ssize_t current_clocksource_show(struct device *dev, |
1051 | struct device_attribute *attr, | |
1052 | char *buf) | |
734efb46 | 1053 | { |
5e2cb101 | 1054 | ssize_t count = 0; |
734efb46 | 1055 | |
75c5158f | 1056 | mutex_lock(&clocksource_mutex); |
5e2cb101 | 1057 | count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); |
75c5158f | 1058 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1059 | |
5e2cb101 | 1060 | return count; |
734efb46 JS |
1061 | } |
1062 | ||
891292a7 | 1063 | ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt) |
29b54078 TG |
1064 | { |
1065 | size_t ret = cnt; | |
1066 | ||
1067 | /* strings from sysfs write are not 0 terminated! */ | |
1068 | if (!cnt || cnt >= CS_NAME_LEN) | |
1069 | return -EINVAL; | |
1070 | ||
1071 | /* strip of \n: */ | |
1072 | if (buf[cnt-1] == '\n') | |
1073 | cnt--; | |
1074 | if (cnt > 0) | |
1075 | memcpy(dst, buf, cnt); | |
1076 | dst[cnt] = 0; | |
1077 | return ret; | |
1078 | } | |
1079 | ||
734efb46 | 1080 | /** |
e87821d1 | 1081 | * current_clocksource_store - interface for manually overriding clocksource |
734efb46 | 1082 | * @dev: unused |
b1b73d09 | 1083 | * @attr: unused |
734efb46 JS |
1084 | * @buf: name of override clocksource |
1085 | * @count: length of buffer | |
1086 | * | |
1087 | * Takes input from sysfs interface for manually overriding the default | |
b71a8eb0 | 1088 | * clocksource selection. |
734efb46 | 1089 | */ |
e87821d1 BW |
1090 | static ssize_t current_clocksource_store(struct device *dev, |
1091 | struct device_attribute *attr, | |
1092 | const char *buf, size_t count) | |
734efb46 | 1093 | { |
233bcb41 | 1094 | ssize_t ret; |
734efb46 | 1095 | |
75c5158f | 1096 | mutex_lock(&clocksource_mutex); |
734efb46 | 1097 | |
03e13cf5 | 1098 | ret = sysfs_get_uname(buf, override_name, count); |
29b54078 TG |
1099 | if (ret >= 0) |
1100 | clocksource_select(); | |
734efb46 | 1101 | |
75c5158f | 1102 | mutex_unlock(&clocksource_mutex); |
734efb46 JS |
1103 | |
1104 | return ret; | |
1105 | } | |
e87821d1 | 1106 | static DEVICE_ATTR_RW(current_clocksource); |
734efb46 | 1107 | |
7eaeb343 | 1108 | /** |
e87821d1 | 1109 | * unbind_clocksource_store - interface for manually unbinding clocksource |
7eaeb343 TG |
1110 | * @dev: unused |
1111 | * @attr: unused | |
1112 | * @buf: unused | |
1113 | * @count: length of buffer | |
1114 | * | |
1115 | * Takes input from sysfs interface for manually unbinding a clocksource. | |
1116 | */ | |
e87821d1 | 1117 | static ssize_t unbind_clocksource_store(struct device *dev, |
7eaeb343 TG |
1118 | struct device_attribute *attr, |
1119 | const char *buf, size_t count) | |
1120 | { | |
1121 | struct clocksource *cs; | |
1122 | char name[CS_NAME_LEN]; | |
233bcb41 | 1123 | ssize_t ret; |
7eaeb343 | 1124 | |
03e13cf5 | 1125 | ret = sysfs_get_uname(buf, name, count); |
7eaeb343 TG |
1126 | if (ret < 0) |
1127 | return ret; | |
1128 | ||
1129 | ret = -ENODEV; | |
1130 | mutex_lock(&clocksource_mutex); | |
1131 | list_for_each_entry(cs, &clocksource_list, list) { | |
1132 | if (strcmp(cs->name, name)) | |
1133 | continue; | |
1134 | ret = clocksource_unbind(cs); | |
1135 | break; | |
1136 | } | |
1137 | mutex_unlock(&clocksource_mutex); | |
1138 | ||
1139 | return ret ? ret : count; | |
1140 | } | |
e87821d1 | 1141 | static DEVICE_ATTR_WO(unbind_clocksource); |
7eaeb343 | 1142 | |
734efb46 | 1143 | /** |
e87821d1 | 1144 | * available_clocksource_show - sysfs interface for listing clocksource |
734efb46 | 1145 | * @dev: unused |
b1b73d09 | 1146 | * @attr: unused |
734efb46 JS |
1147 | * @buf: char buffer to be filled with clocksource list |
1148 | * | |
1149 | * Provides sysfs interface for listing registered clocksources | |
1150 | */ | |
e87821d1 BW |
1151 | static ssize_t available_clocksource_show(struct device *dev, |
1152 | struct device_attribute *attr, | |
1153 | char *buf) | |
734efb46 | 1154 | { |
2e197586 | 1155 | struct clocksource *src; |
5e2cb101 | 1156 | ssize_t count = 0; |
734efb46 | 1157 | |
75c5158f | 1158 | mutex_lock(&clocksource_mutex); |
2e197586 | 1159 | list_for_each_entry(src, &clocksource_list, list) { |
cd6d95d8 TG |
1160 | /* |
1161 | * Don't show non-HRES clocksource if the tick code is | |
1162 | * in one shot mode (highres=on or nohz=on) | |
1163 | */ | |
1164 | if (!tick_oneshot_mode_active() || | |
1165 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) | |
3f68535a | 1166 | count += snprintf(buf + count, |
5e2cb101 MX |
1167 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), |
1168 | "%s ", src->name); | |
734efb46 | 1169 | } |
75c5158f | 1170 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1171 | |
5e2cb101 MX |
1172 | count += snprintf(buf + count, |
1173 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); | |
734efb46 | 1174 | |
5e2cb101 | 1175 | return count; |
734efb46 | 1176 | } |
e87821d1 | 1177 | static DEVICE_ATTR_RO(available_clocksource); |
734efb46 | 1178 | |
27263e8d BW |
1179 | static struct attribute *clocksource_attrs[] = { |
1180 | &dev_attr_current_clocksource.attr, | |
1181 | &dev_attr_unbind_clocksource.attr, | |
1182 | &dev_attr_available_clocksource.attr, | |
1183 | NULL | |
1184 | }; | |
1185 | ATTRIBUTE_GROUPS(clocksource); | |
1186 | ||
d369a5d8 | 1187 | static struct bus_type clocksource_subsys = { |
af5ca3f4 | 1188 | .name = "clocksource", |
d369a5d8 | 1189 | .dev_name = "clocksource", |
734efb46 JS |
1190 | }; |
1191 | ||
d369a5d8 | 1192 | static struct device device_clocksource = { |
734efb46 | 1193 | .id = 0, |
d369a5d8 | 1194 | .bus = &clocksource_subsys, |
27263e8d | 1195 | .groups = clocksource_groups, |
734efb46 JS |
1196 | }; |
1197 | ||
ad596171 | 1198 | static int __init init_clocksource_sysfs(void) |
734efb46 | 1199 | { |
d369a5d8 | 1200 | int error = subsys_system_register(&clocksource_subsys, NULL); |
734efb46 JS |
1201 | |
1202 | if (!error) | |
d369a5d8 | 1203 | error = device_register(&device_clocksource); |
27263e8d | 1204 | |
734efb46 JS |
1205 | return error; |
1206 | } | |
1207 | ||
1208 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 1209 | #endif /* CONFIG_SYSFS */ |
734efb46 JS |
1210 | |
1211 | /** | |
1212 | * boot_override_clocksource - boot clock override | |
1213 | * @str: override name | |
1214 | * | |
1215 | * Takes a clocksource= boot argument and uses it | |
1216 | * as the clocksource override name. | |
1217 | */ | |
1218 | static int __init boot_override_clocksource(char* str) | |
1219 | { | |
75c5158f | 1220 | mutex_lock(&clocksource_mutex); |
734efb46 JS |
1221 | if (str) |
1222 | strlcpy(override_name, str, sizeof(override_name)); | |
75c5158f | 1223 | mutex_unlock(&clocksource_mutex); |
734efb46 JS |
1224 | return 1; |
1225 | } | |
1226 | ||
1227 | __setup("clocksource=", boot_override_clocksource); | |
1228 | ||
1229 | /** | |
1230 | * boot_override_clock - Compatibility layer for deprecated boot option | |
1231 | * @str: override name | |
1232 | * | |
1233 | * DEPRECATED! Takes a clock= boot argument and uses it | |
1234 | * as the clocksource override name | |
1235 | */ | |
1236 | static int __init boot_override_clock(char* str) | |
1237 | { | |
5d0cf410 | 1238 | if (!strcmp(str, "pmtmr")) { |
45bbfe64 | 1239 | pr_warn("clock=pmtmr is deprecated - use clocksource=acpi_pm\n"); |
5d0cf410 JS |
1240 | return boot_override_clocksource("acpi_pm"); |
1241 | } | |
45bbfe64 | 1242 | pr_warn("clock= boot option is deprecated - use clocksource=xyz\n"); |
734efb46 JS |
1243 | return boot_override_clocksource(str); |
1244 | } | |
1245 | ||
1246 | __setup("clock=", boot_override_clock); |