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35728b82 | 1 | // SPDX-License-Identifier: GPL-2.0+ |
734efb46 | 2 | /* |
734efb46 | 3 | * This file contains the functions which manage clocksource drivers. |
4 | * | |
5 | * Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) | |
734efb46 | 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 | 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> |
fa218f1c PM |
17 | #include <linux/prandom.h> |
18 | #include <linux/cpu.h> | |
734efb46 | 19 | |
c1797baf | 20 | #include "tick-internal.h" |
3a978377 | 21 | #include "timekeeping_internal.h" |
03e13cf5 | 22 | |
7d2f944a TG |
23 | /** |
24 | * clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks | |
25 | * @mult: pointer to mult variable | |
26 | * @shift: pointer to shift variable | |
27 | * @from: frequency to convert from | |
28 | * @to: frequency to convert to | |
5fdade95 | 29 | * @maxsec: guaranteed runtime conversion range in seconds |
7d2f944a TG |
30 | * |
31 | * The function evaluates the shift/mult pair for the scaled math | |
32 | * operations of clocksources and clockevents. | |
33 | * | |
34 | * @to and @from are frequency values in HZ. For clock sources @to is | |
35 | * NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock | |
36 | * event @to is the counter frequency and @from is NSEC_PER_SEC. | |
37 | * | |
5fdade95 | 38 | * The @maxsec conversion range argument controls the time frame in |
7d2f944a TG |
39 | * seconds which must be covered by the runtime conversion with the |
40 | * calculated mult and shift factors. This guarantees that no 64bit | |
41 | * overflow happens when the input value of the conversion is | |
42 | * multiplied with the calculated mult factor. Larger ranges may | |
4bf07f65 | 43 | * reduce the conversion accuracy by choosing smaller mult and shift |
7d2f944a TG |
44 | * factors. |
45 | */ | |
46 | void | |
5fdade95 | 47 | clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 maxsec) |
7d2f944a TG |
48 | { |
49 | u64 tmp; | |
50 | u32 sft, sftacc= 32; | |
51 | ||
52 | /* | |
53 | * Calculate the shift factor which is limiting the conversion | |
54 | * range: | |
55 | */ | |
5fdade95 | 56 | tmp = ((u64)maxsec * from) >> 32; |
7d2f944a TG |
57 | while (tmp) { |
58 | tmp >>=1; | |
59 | sftacc--; | |
60 | } | |
61 | ||
62 | /* | |
63 | * Find the conversion shift/mult pair which has the best | |
64 | * accuracy and fits the maxsec conversion range: | |
65 | */ | |
66 | for (sft = 32; sft > 0; sft--) { | |
67 | tmp = (u64) to << sft; | |
b5776c4a | 68 | tmp += from / 2; |
7d2f944a TG |
69 | do_div(tmp, from); |
70 | if ((tmp >> sftacc) == 0) | |
71 | break; | |
72 | } | |
73 | *mult = tmp; | |
74 | *shift = sft; | |
75 | } | |
5304121a | 76 | EXPORT_SYMBOL_GPL(clocks_calc_mult_shift); |
7d2f944a | 77 | |
734efb46 | 78 | /*[Clocksource internal variables]--------- |
79 | * curr_clocksource: | |
f1b82746 | 80 | * currently selected clocksource. |
39232ed5 BW |
81 | * suspend_clocksource: |
82 | * used to calculate the suspend time. | |
734efb46 | 83 | * clocksource_list: |
84 | * linked list with the registered clocksources | |
75c5158f MS |
85 | * clocksource_mutex: |
86 | * protects manipulations to curr_clocksource and the clocksource_list | |
734efb46 | 87 | * override_name: |
88 | * Name of the user-specified clocksource. | |
89 | */ | |
f1b82746 | 90 | static struct clocksource *curr_clocksource; |
39232ed5 | 91 | static struct clocksource *suspend_clocksource; |
734efb46 | 92 | static LIST_HEAD(clocksource_list); |
75c5158f | 93 | static DEFINE_MUTEX(clocksource_mutex); |
29b54078 | 94 | static char override_name[CS_NAME_LEN]; |
54a6bc0b | 95 | static int finished_booting; |
39232ed5 | 96 | static u64 suspend_start; |
734efb46 | 97 | |
2e27e793 PM |
98 | /* |
99 | * Threshold: 0.0312s, when doubled: 0.0625s. | |
100 | * Also a default for cs->uncertainty_margin when registering clocks. | |
101 | */ | |
102 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 5) | |
103 | ||
104 | /* | |
105 | * Maximum permissible delay between two readouts of the watchdog | |
106 | * clocksource surrounding a read of the clocksource being validated. | |
107 | * This delay could be due to SMIs, NMIs, or to VCPU preemptions. Used as | |
108 | * a lower bound for cs->uncertainty_margin values when registering clocks. | |
109 | */ | |
fc153c1c WL |
110 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG_MAX_SKEW_US |
111 | #define MAX_SKEW_USEC CONFIG_CLOCKSOURCE_WATCHDOG_MAX_SKEW_US | |
112 | #else | |
113 | #define MAX_SKEW_USEC 100 | |
114 | #endif | |
115 | ||
116 | #define WATCHDOG_MAX_SKEW (MAX_SKEW_USEC * NSEC_PER_USEC) | |
2e27e793 | 117 | |
5d8b34fd | 118 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
f79e0258 | 119 | static void clocksource_watchdog_work(struct work_struct *work); |
332962f2 | 120 | static void clocksource_select(void); |
f79e0258 | 121 | |
5d8b34fd TG |
122 | static LIST_HEAD(watchdog_list); |
123 | static struct clocksource *watchdog; | |
124 | static struct timer_list watchdog_timer; | |
f79e0258 | 125 | static DECLARE_WORK(watchdog_work, clocksource_watchdog_work); |
5d8b34fd | 126 | static DEFINE_SPINLOCK(watchdog_lock); |
fb63a0eb | 127 | static int watchdog_running; |
9fb60336 | 128 | static atomic_t watchdog_reset_pending; |
b52f52a0 | 129 | |
0f48b41f | 130 | static inline void clocksource_watchdog_lock(unsigned long *flags) |
2aae7bcf PZ |
131 | { |
132 | spin_lock_irqsave(&watchdog_lock, *flags); | |
133 | } | |
134 | ||
0f48b41f | 135 | static inline void clocksource_watchdog_unlock(unsigned long *flags) |
2aae7bcf PZ |
136 | { |
137 | spin_unlock_irqrestore(&watchdog_lock, *flags); | |
138 | } | |
139 | ||
e2c631ba PZ |
140 | static int clocksource_watchdog_kthread(void *data); |
141 | static void __clocksource_change_rating(struct clocksource *cs, int rating); | |
142 | ||
5d8b34fd | 143 | /* |
2e27e793 | 144 | * Interval: 0.5sec. |
5d8b34fd TG |
145 | */ |
146 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
db3a34e1 | 147 | |
e2c631ba PZ |
148 | static void clocksource_watchdog_work(struct work_struct *work) |
149 | { | |
150 | /* | |
151 | * We cannot directly run clocksource_watchdog_kthread() here, because | |
152 | * clocksource_select() calls timekeeping_notify() which uses | |
153 | * stop_machine(). One cannot use stop_machine() from a workqueue() due | |
154 | * lock inversions wrt CPU hotplug. | |
155 | * | |
156 | * Also, we only ever run this work once or twice during the lifetime | |
157 | * of the kernel, so there is no point in creating a more permanent | |
158 | * kthread for this. | |
159 | * | |
160 | * If kthread_run fails the next watchdog scan over the | |
161 | * watchdog_list will find the unstable clock again. | |
162 | */ | |
163 | kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog"); | |
164 | } | |
165 | ||
7285dd7f | 166 | static void __clocksource_unstable(struct clocksource *cs) |
5d8b34fd | 167 | { |
5d8b34fd | 168 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); |
c55c87c8 | 169 | cs->flags |= CLOCK_SOURCE_UNSTABLE; |
12907fbb | 170 | |
cd2af07d | 171 | /* |
e2c631ba | 172 | * If the clocksource is registered clocksource_watchdog_kthread() will |
cd2af07d PZ |
173 | * re-rate and re-select. |
174 | */ | |
175 | if (list_empty(&cs->list)) { | |
176 | cs->rating = 0; | |
2aae7bcf | 177 | return; |
cd2af07d | 178 | } |
2aae7bcf | 179 | |
12907fbb TG |
180 | if (cs->mark_unstable) |
181 | cs->mark_unstable(cs); | |
182 | ||
e2c631ba | 183 | /* kick clocksource_watchdog_kthread() */ |
54a6bc0b TG |
184 | if (finished_booting) |
185 | schedule_work(&watchdog_work); | |
5d8b34fd TG |
186 | } |
187 | ||
7285dd7f TG |
188 | /** |
189 | * clocksource_mark_unstable - mark clocksource unstable via watchdog | |
190 | * @cs: clocksource to be marked unstable | |
191 | * | |
7dba33c6 | 192 | * This function is called by the x86 TSC code to mark clocksources as unstable; |
e2c631ba | 193 | * it defers demotion and re-selection to a kthread. |
7285dd7f TG |
194 | */ |
195 | void clocksource_mark_unstable(struct clocksource *cs) | |
196 | { | |
197 | unsigned long flags; | |
198 | ||
199 | spin_lock_irqsave(&watchdog_lock, flags); | |
200 | if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) { | |
2aae7bcf | 201 | if (!list_empty(&cs->list) && list_empty(&cs->wd_list)) |
7285dd7f TG |
202 | list_add(&cs->wd_list, &watchdog_list); |
203 | __clocksource_unstable(cs); | |
204 | } | |
205 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
206 | } | |
207 | ||
1a562067 | 208 | ulong max_cswd_read_retries = 2; |
db3a34e1 | 209 | module_param(max_cswd_read_retries, ulong, 0644); |
1253b9b8 | 210 | EXPORT_SYMBOL_GPL(max_cswd_read_retries); |
fa218f1c PM |
211 | static int verify_n_cpus = 8; |
212 | module_param(verify_n_cpus, int, 0644); | |
db3a34e1 | 213 | |
c86ff8c5 WL |
214 | enum wd_read_status { |
215 | WD_READ_SUCCESS, | |
216 | WD_READ_UNSTABLE, | |
217 | WD_READ_SKIP | |
218 | }; | |
219 | ||
220 | static enum wd_read_status cs_watchdog_read(struct clocksource *cs, u64 *csnow, u64 *wdnow) | |
db3a34e1 PM |
221 | { |
222 | unsigned int nretries; | |
c86ff8c5 WL |
223 | u64 wd_end, wd_end2, wd_delta; |
224 | int64_t wd_delay, wd_seq_delay; | |
db3a34e1 PM |
225 | |
226 | for (nretries = 0; nretries <= max_cswd_read_retries; nretries++) { | |
227 | local_irq_disable(); | |
228 | *wdnow = watchdog->read(watchdog); | |
229 | *csnow = cs->read(cs); | |
230 | wd_end = watchdog->read(watchdog); | |
c86ff8c5 | 231 | wd_end2 = watchdog->read(watchdog); |
db3a34e1 PM |
232 | local_irq_enable(); |
233 | ||
234 | wd_delta = clocksource_delta(wd_end, *wdnow, watchdog->mask); | |
235 | wd_delay = clocksource_cyc2ns(wd_delta, watchdog->mult, | |
236 | watchdog->shift); | |
237 | if (wd_delay <= WATCHDOG_MAX_SKEW) { | |
238 | if (nretries > 1 || nretries >= max_cswd_read_retries) { | |
239 | pr_warn("timekeeping watchdog on CPU%d: %s retried %d times before success\n", | |
240 | smp_processor_id(), watchdog->name, nretries); | |
241 | } | |
c86ff8c5 | 242 | return WD_READ_SUCCESS; |
db3a34e1 | 243 | } |
c86ff8c5 WL |
244 | |
245 | /* | |
246 | * Now compute delay in consecutive watchdog read to see if | |
247 | * there is too much external interferences that cause | |
248 | * significant delay in reading both clocksource and watchdog. | |
249 | * | |
250 | * If consecutive WD read-back delay > WATCHDOG_MAX_SKEW/2, | |
251 | * report system busy, reinit the watchdog and skip the current | |
252 | * watchdog test. | |
253 | */ | |
254 | wd_delta = clocksource_delta(wd_end2, wd_end, watchdog->mask); | |
255 | wd_seq_delay = clocksource_cyc2ns(wd_delta, watchdog->mult, watchdog->shift); | |
256 | if (wd_seq_delay > WATCHDOG_MAX_SKEW/2) | |
257 | goto skip_test; | |
db3a34e1 PM |
258 | } |
259 | ||
260 | pr_warn("timekeeping watchdog on CPU%d: %s read-back delay of %lldns, attempt %d, marking unstable\n", | |
261 | smp_processor_id(), watchdog->name, wd_delay, nretries); | |
c86ff8c5 WL |
262 | return WD_READ_UNSTABLE; |
263 | ||
264 | skip_test: | |
265 | pr_info("timekeeping watchdog on CPU%d: %s wd-wd read-back delay of %lldns\n", | |
266 | smp_processor_id(), watchdog->name, wd_seq_delay); | |
267 | pr_info("wd-%s-wd read-back delay of %lldns, clock-skew test skipped!\n", | |
268 | cs->name, wd_delay); | |
269 | return WD_READ_SKIP; | |
db3a34e1 PM |
270 | } |
271 | ||
7560c02b PM |
272 | static u64 csnow_mid; |
273 | static cpumask_t cpus_ahead; | |
274 | static cpumask_t cpus_behind; | |
fa218f1c PM |
275 | static cpumask_t cpus_chosen; |
276 | ||
277 | static void clocksource_verify_choose_cpus(void) | |
278 | { | |
279 | int cpu, i, n = verify_n_cpus; | |
280 | ||
281 | if (n < 0) { | |
282 | /* Check all of the CPUs. */ | |
283 | cpumask_copy(&cpus_chosen, cpu_online_mask); | |
284 | cpumask_clear_cpu(smp_processor_id(), &cpus_chosen); | |
285 | return; | |
286 | } | |
287 | ||
288 | /* If no checking desired, or no other CPU to check, leave. */ | |
289 | cpumask_clear(&cpus_chosen); | |
290 | if (n == 0 || num_online_cpus() <= 1) | |
291 | return; | |
292 | ||
293 | /* Make sure to select at least one CPU other than the current CPU. */ | |
9b51d9d8 | 294 | cpu = cpumask_first(cpu_online_mask); |
fa218f1c PM |
295 | if (cpu == smp_processor_id()) |
296 | cpu = cpumask_next(cpu, cpu_online_mask); | |
297 | if (WARN_ON_ONCE(cpu >= nr_cpu_ids)) | |
298 | return; | |
299 | cpumask_set_cpu(cpu, &cpus_chosen); | |
300 | ||
301 | /* Force a sane value for the boot parameter. */ | |
302 | if (n > nr_cpu_ids) | |
303 | n = nr_cpu_ids; | |
304 | ||
305 | /* | |
306 | * Randomly select the specified number of CPUs. If the same | |
307 | * CPU is selected multiple times, that CPU is checked only once, | |
308 | * and no replacement CPU is selected. This gracefully handles | |
309 | * situations where verify_n_cpus is greater than the number of | |
310 | * CPUs that are currently online. | |
311 | */ | |
312 | for (i = 1; i < n; i++) { | |
313 | cpu = prandom_u32() % nr_cpu_ids; | |
314 | cpu = cpumask_next(cpu - 1, cpu_online_mask); | |
315 | if (cpu >= nr_cpu_ids) | |
9b51d9d8 | 316 | cpu = cpumask_first(cpu_online_mask); |
fa218f1c PM |
317 | if (!WARN_ON_ONCE(cpu >= nr_cpu_ids)) |
318 | cpumask_set_cpu(cpu, &cpus_chosen); | |
319 | } | |
320 | ||
321 | /* Don't verify ourselves. */ | |
322 | cpumask_clear_cpu(smp_processor_id(), &cpus_chosen); | |
323 | } | |
7560c02b PM |
324 | |
325 | static void clocksource_verify_one_cpu(void *csin) | |
326 | { | |
327 | struct clocksource *cs = (struct clocksource *)csin; | |
328 | ||
329 | csnow_mid = cs->read(cs); | |
330 | } | |
331 | ||
1253b9b8 | 332 | void clocksource_verify_percpu(struct clocksource *cs) |
7560c02b PM |
333 | { |
334 | int64_t cs_nsec, cs_nsec_max = 0, cs_nsec_min = LLONG_MAX; | |
335 | u64 csnow_begin, csnow_end; | |
336 | int cpu, testcpu; | |
337 | s64 delta; | |
338 | ||
fa218f1c PM |
339 | if (verify_n_cpus == 0) |
340 | return; | |
7560c02b PM |
341 | cpumask_clear(&cpus_ahead); |
342 | cpumask_clear(&cpus_behind); | |
698429f9 | 343 | cpus_read_lock(); |
7560c02b | 344 | preempt_disable(); |
fa218f1c | 345 | clocksource_verify_choose_cpus(); |
8afbcaf8 | 346 | if (cpumask_empty(&cpus_chosen)) { |
fa218f1c | 347 | preempt_enable(); |
698429f9 | 348 | cpus_read_unlock(); |
fa218f1c PM |
349 | pr_warn("Not enough CPUs to check clocksource '%s'.\n", cs->name); |
350 | return; | |
351 | } | |
7560c02b | 352 | testcpu = smp_processor_id(); |
fa218f1c PM |
353 | pr_warn("Checking clocksource %s synchronization from CPU %d to CPUs %*pbl.\n", cs->name, testcpu, cpumask_pr_args(&cpus_chosen)); |
354 | for_each_cpu(cpu, &cpus_chosen) { | |
7560c02b PM |
355 | if (cpu == testcpu) |
356 | continue; | |
357 | csnow_begin = cs->read(cs); | |
358 | smp_call_function_single(cpu, clocksource_verify_one_cpu, cs, 1); | |
359 | csnow_end = cs->read(cs); | |
360 | delta = (s64)((csnow_mid - csnow_begin) & cs->mask); | |
361 | if (delta < 0) | |
362 | cpumask_set_cpu(cpu, &cpus_behind); | |
363 | delta = (csnow_end - csnow_mid) & cs->mask; | |
364 | if (delta < 0) | |
365 | cpumask_set_cpu(cpu, &cpus_ahead); | |
366 | delta = clocksource_delta(csnow_end, csnow_begin, cs->mask); | |
367 | cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift); | |
368 | if (cs_nsec > cs_nsec_max) | |
369 | cs_nsec_max = cs_nsec; | |
370 | if (cs_nsec < cs_nsec_min) | |
371 | cs_nsec_min = cs_nsec; | |
372 | } | |
373 | preempt_enable(); | |
698429f9 | 374 | cpus_read_unlock(); |
7560c02b PM |
375 | if (!cpumask_empty(&cpus_ahead)) |
376 | pr_warn(" CPUs %*pbl ahead of CPU %d for clocksource %s.\n", | |
377 | cpumask_pr_args(&cpus_ahead), testcpu, cs->name); | |
378 | if (!cpumask_empty(&cpus_behind)) | |
379 | pr_warn(" CPUs %*pbl behind CPU %d for clocksource %s.\n", | |
380 | cpumask_pr_args(&cpus_behind), testcpu, cs->name); | |
381 | if (!cpumask_empty(&cpus_ahead) || !cpumask_empty(&cpus_behind)) | |
382 | pr_warn(" CPU %d check durations %lldns - %lldns for clocksource %s.\n", | |
383 | testcpu, cs_nsec_min, cs_nsec_max, cs->name); | |
384 | } | |
1253b9b8 | 385 | EXPORT_SYMBOL_GPL(clocksource_verify_percpu); |
7560c02b | 386 | |
e99e88a9 | 387 | static void clocksource_watchdog(struct timer_list *unused) |
5d8b34fd | 388 | { |
a5a1d1c2 | 389 | u64 csnow, wdnow, cslast, wdlast, delta; |
9fb60336 | 390 | int next_cpu, reset_pending; |
db3a34e1 PM |
391 | int64_t wd_nsec, cs_nsec; |
392 | struct clocksource *cs; | |
c86ff8c5 | 393 | enum wd_read_status read_ret; |
2e27e793 | 394 | u32 md; |
5d8b34fd TG |
395 | |
396 | spin_lock(&watchdog_lock); | |
fb63a0eb MS |
397 | if (!watchdog_running) |
398 | goto out; | |
5d8b34fd | 399 | |
9fb60336 TG |
400 | reset_pending = atomic_read(&watchdog_reset_pending); |
401 | ||
c55c87c8 MS |
402 | list_for_each_entry(cs, &watchdog_list, wd_list) { |
403 | ||
404 | /* Clocksource already marked unstable? */ | |
01548f4d | 405 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
54a6bc0b TG |
406 | if (finished_booting) |
407 | schedule_work(&watchdog_work); | |
c55c87c8 | 408 | continue; |
01548f4d | 409 | } |
c55c87c8 | 410 | |
c86ff8c5 WL |
411 | read_ret = cs_watchdog_read(cs, &csnow, &wdnow); |
412 | ||
413 | if (read_ret != WD_READ_SUCCESS) { | |
414 | if (read_ret == WD_READ_UNSTABLE) | |
415 | /* Clock readout unreliable, so give it up. */ | |
416 | __clocksource_unstable(cs); | |
db3a34e1 PM |
417 | continue; |
418 | } | |
b52f52a0 | 419 | |
8cf4e750 | 420 | /* Clocksource initialized ? */ |
9fb60336 TG |
421 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) || |
422 | atomic_read(&watchdog_reset_pending)) { | |
8cf4e750 | 423 | cs->flags |= CLOCK_SOURCE_WATCHDOG; |
b5199515 TG |
424 | cs->wd_last = wdnow; |
425 | cs->cs_last = csnow; | |
b52f52a0 TG |
426 | continue; |
427 | } | |
428 | ||
3a978377 TG |
429 | delta = clocksource_delta(wdnow, cs->wd_last, watchdog->mask); |
430 | wd_nsec = clocksource_cyc2ns(delta, watchdog->mult, | |
431 | watchdog->shift); | |
b5199515 | 432 | |
3a978377 TG |
433 | delta = clocksource_delta(csnow, cs->cs_last, cs->mask); |
434 | cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift); | |
0b046b21 JS |
435 | wdlast = cs->wd_last; /* save these in case we print them */ |
436 | cslast = cs->cs_last; | |
b5199515 TG |
437 | cs->cs_last = csnow; |
438 | cs->wd_last = wdnow; | |
439 | ||
9fb60336 TG |
440 | if (atomic_read(&watchdog_reset_pending)) |
441 | continue; | |
442 | ||
b5199515 | 443 | /* Check the deviation from the watchdog clocksource. */ |
2e27e793 PM |
444 | md = cs->uncertainty_margin + watchdog->uncertainty_margin; |
445 | if (abs(cs_nsec - wd_nsec) > md) { | |
390dd67c SI |
446 | pr_warn("timekeeping watchdog on CPU%d: Marking clocksource '%s' as unstable because the skew is too large:\n", |
447 | smp_processor_id(), cs->name); | |
22a22383 FT |
448 | pr_warn(" '%s' wd_nsec: %lld wd_now: %llx wd_last: %llx mask: %llx\n", |
449 | watchdog->name, wd_nsec, wdnow, wdlast, watchdog->mask); | |
450 | pr_warn(" '%s' cs_nsec: %lld cs_now: %llx cs_last: %llx mask: %llx\n", | |
451 | cs->name, cs_nsec, csnow, cslast, cs->mask); | |
fa218f1c PM |
452 | if (curr_clocksource == cs) |
453 | pr_warn(" '%s' is current clocksource.\n", cs->name); | |
454 | else if (curr_clocksource) | |
455 | pr_warn(" '%s' (not '%s') is current clocksource.\n", curr_clocksource->name, cs->name); | |
456 | else | |
457 | pr_warn(" No current clocksource.\n"); | |
0b046b21 | 458 | __clocksource_unstable(cs); |
8cf4e750 MS |
459 | continue; |
460 | } | |
461 | ||
b421b22b PZ |
462 | if (cs == curr_clocksource && cs->tick_stable) |
463 | cs->tick_stable(cs); | |
464 | ||
8cf4e750 MS |
465 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && |
466 | (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
467 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
332962f2 | 468 | /* Mark it valid for high-res. */ |
8cf4e750 | 469 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
332962f2 TG |
470 | |
471 | /* | |
472 | * clocksource_done_booting() will sort it if | |
473 | * finished_booting is not set yet. | |
474 | */ | |
475 | if (!finished_booting) | |
476 | continue; | |
477 | ||
8cf4e750 | 478 | /* |
332962f2 TG |
479 | * If this is not the current clocksource let |
480 | * the watchdog thread reselect it. Due to the | |
481 | * change to high res this clocksource might | |
482 | * be preferred now. If it is the current | |
483 | * clocksource let the tick code know about | |
484 | * that change. | |
8cf4e750 | 485 | */ |
332962f2 TG |
486 | if (cs != curr_clocksource) { |
487 | cs->flags |= CLOCK_SOURCE_RESELECT; | |
488 | schedule_work(&watchdog_work); | |
489 | } else { | |
490 | tick_clock_notify(); | |
491 | } | |
5d8b34fd TG |
492 | } |
493 | } | |
494 | ||
9fb60336 TG |
495 | /* |
496 | * We only clear the watchdog_reset_pending, when we did a | |
497 | * full cycle through all clocksources. | |
498 | */ | |
499 | if (reset_pending) | |
500 | atomic_dec(&watchdog_reset_pending); | |
501 | ||
c55c87c8 MS |
502 | /* |
503 | * Cycle through CPUs to check if the CPUs stay synchronized | |
504 | * to each other. | |
505 | */ | |
506 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); | |
507 | if (next_cpu >= nr_cpu_ids) | |
508 | next_cpu = cpumask_first(cpu_online_mask); | |
febac332 KK |
509 | |
510 | /* | |
511 | * Arm timer if not already pending: could race with concurrent | |
512 | * pair clocksource_stop_watchdog() clocksource_start_watchdog(). | |
513 | */ | |
514 | if (!timer_pending(&watchdog_timer)) { | |
515 | watchdog_timer.expires += WATCHDOG_INTERVAL; | |
516 | add_timer_on(&watchdog_timer, next_cpu); | |
517 | } | |
fb63a0eb | 518 | out: |
5d8b34fd TG |
519 | spin_unlock(&watchdog_lock); |
520 | } | |
0f8e8ef7 | 521 | |
fb63a0eb MS |
522 | static inline void clocksource_start_watchdog(void) |
523 | { | |
524 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) | |
525 | return; | |
e99e88a9 | 526 | timer_setup(&watchdog_timer, clocksource_watchdog, 0); |
fb63a0eb MS |
527 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; |
528 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); | |
529 | watchdog_running = 1; | |
530 | } | |
531 | ||
532 | static inline void clocksource_stop_watchdog(void) | |
533 | { | |
534 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) | |
535 | return; | |
536 | del_timer(&watchdog_timer); | |
537 | watchdog_running = 0; | |
538 | } | |
539 | ||
0f8e8ef7 MS |
540 | static inline void clocksource_reset_watchdog(void) |
541 | { | |
542 | struct clocksource *cs; | |
543 | ||
544 | list_for_each_entry(cs, &watchdog_list, wd_list) | |
545 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
546 | } | |
547 | ||
b52f52a0 TG |
548 | static void clocksource_resume_watchdog(void) |
549 | { | |
9fb60336 | 550 | atomic_inc(&watchdog_reset_pending); |
b52f52a0 TG |
551 | } |
552 | ||
fb63a0eb | 553 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
5d8b34fd | 554 | { |
5b9e886a PZ |
555 | INIT_LIST_HEAD(&cs->wd_list); |
556 | ||
5d8b34fd | 557 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { |
fb63a0eb | 558 | /* cs is a clocksource to be watched. */ |
5d8b34fd | 559 | list_add(&cs->wd_list, &watchdog_list); |
fb63a0eb | 560 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
948ac6d7 | 561 | } else { |
fb63a0eb | 562 | /* cs is a watchdog. */ |
948ac6d7 | 563 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
5d8b34fd | 564 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
bbf66d89 | 565 | } |
bbf66d89 VK |
566 | } |
567 | ||
568 | static void clocksource_select_watchdog(bool fallback) | |
569 | { | |
570 | struct clocksource *cs, *old_wd; | |
571 | unsigned long flags; | |
572 | ||
573 | spin_lock_irqsave(&watchdog_lock, flags); | |
574 | /* save current watchdog */ | |
575 | old_wd = watchdog; | |
576 | if (fallback) | |
577 | watchdog = NULL; | |
578 | ||
579 | list_for_each_entry(cs, &clocksource_list, list) { | |
580 | /* cs is a clocksource to be watched. */ | |
581 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) | |
582 | continue; | |
583 | ||
584 | /* Skip current if we were requested for a fallback. */ | |
585 | if (fallback && cs == old_wd) | |
586 | continue; | |
587 | ||
fb63a0eb | 588 | /* Pick the best watchdog. */ |
bbf66d89 | 589 | if (!watchdog || cs->rating > watchdog->rating) |
5d8b34fd | 590 | watchdog = cs; |
5d8b34fd | 591 | } |
bbf66d89 VK |
592 | /* If we failed to find a fallback restore the old one. */ |
593 | if (!watchdog) | |
594 | watchdog = old_wd; | |
595 | ||
596 | /* If we changed the watchdog we need to reset cycles. */ | |
597 | if (watchdog != old_wd) | |
598 | clocksource_reset_watchdog(); | |
599 | ||
fb63a0eb MS |
600 | /* Check if the watchdog timer needs to be started. */ |
601 | clocksource_start_watchdog(); | |
5d8b34fd TG |
602 | spin_unlock_irqrestore(&watchdog_lock, flags); |
603 | } | |
fb63a0eb MS |
604 | |
605 | static void clocksource_dequeue_watchdog(struct clocksource *cs) | |
606 | { | |
a89c7edb TG |
607 | if (cs != watchdog) { |
608 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
609 | /* cs is a watched clocksource. */ | |
610 | list_del_init(&cs->wd_list); | |
611 | /* Check if the watchdog timer needs to be stopped. */ | |
612 | clocksource_stop_watchdog(); | |
fb63a0eb MS |
613 | } |
614 | } | |
fb63a0eb MS |
615 | } |
616 | ||
e2c631ba | 617 | static int __clocksource_watchdog_kthread(void) |
c55c87c8 MS |
618 | { |
619 | struct clocksource *cs, *tmp; | |
620 | unsigned long flags; | |
332962f2 | 621 | int select = 0; |
c55c87c8 | 622 | |
7560c02b PM |
623 | /* Do any required per-CPU skew verification. */ |
624 | if (curr_clocksource && | |
625 | curr_clocksource->flags & CLOCK_SOURCE_UNSTABLE && | |
626 | curr_clocksource->flags & CLOCK_SOURCE_VERIFY_PERCPU) | |
627 | clocksource_verify_percpu(curr_clocksource); | |
628 | ||
c55c87c8 | 629 | spin_lock_irqsave(&watchdog_lock, flags); |
332962f2 | 630 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { |
c55c87c8 MS |
631 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
632 | list_del_init(&cs->wd_list); | |
2aae7bcf | 633 | __clocksource_change_rating(cs, 0); |
332962f2 TG |
634 | select = 1; |
635 | } | |
636 | if (cs->flags & CLOCK_SOURCE_RESELECT) { | |
637 | cs->flags &= ~CLOCK_SOURCE_RESELECT; | |
638 | select = 1; | |
c55c87c8 | 639 | } |
332962f2 | 640 | } |
c55c87c8 MS |
641 | /* Check if the watchdog timer needs to be stopped. */ |
642 | clocksource_stop_watchdog(); | |
6ea41d25 TG |
643 | spin_unlock_irqrestore(&watchdog_lock, flags); |
644 | ||
332962f2 TG |
645 | return select; |
646 | } | |
647 | ||
e2c631ba | 648 | static int clocksource_watchdog_kthread(void *data) |
332962f2 TG |
649 | { |
650 | mutex_lock(&clocksource_mutex); | |
e2c631ba | 651 | if (__clocksource_watchdog_kthread()) |
332962f2 | 652 | clocksource_select(); |
d0981a1b | 653 | mutex_unlock(&clocksource_mutex); |
e2c631ba | 654 | return 0; |
c55c87c8 MS |
655 | } |
656 | ||
7eaeb343 TG |
657 | static bool clocksource_is_watchdog(struct clocksource *cs) |
658 | { | |
659 | return cs == watchdog; | |
660 | } | |
661 | ||
fb63a0eb MS |
662 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
663 | ||
664 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
5d8b34fd TG |
665 | { |
666 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
667 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
668 | } | |
b52f52a0 | 669 | |
bbf66d89 | 670 | static void clocksource_select_watchdog(bool fallback) { } |
fb63a0eb | 671 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
b52f52a0 | 672 | static inline void clocksource_resume_watchdog(void) { } |
e2c631ba | 673 | static inline int __clocksource_watchdog_kthread(void) { return 0; } |
7eaeb343 | 674 | static bool clocksource_is_watchdog(struct clocksource *cs) { return false; } |
397bbf6d | 675 | void clocksource_mark_unstable(struct clocksource *cs) { } |
fb63a0eb | 676 | |
db6f9e55 MM |
677 | static inline void clocksource_watchdog_lock(unsigned long *flags) { } |
678 | static inline void clocksource_watchdog_unlock(unsigned long *flags) { } | |
2aae7bcf | 679 | |
fb63a0eb | 680 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
5d8b34fd | 681 | |
39232ed5 BW |
682 | static bool clocksource_is_suspend(struct clocksource *cs) |
683 | { | |
684 | return cs == suspend_clocksource; | |
685 | } | |
686 | ||
687 | static void __clocksource_suspend_select(struct clocksource *cs) | |
688 | { | |
689 | /* | |
690 | * Skip the clocksource which will be stopped in suspend state. | |
691 | */ | |
692 | if (!(cs->flags & CLOCK_SOURCE_SUSPEND_NONSTOP)) | |
693 | return; | |
694 | ||
695 | /* | |
696 | * The nonstop clocksource can be selected as the suspend clocksource to | |
697 | * calculate the suspend time, so it should not supply suspend/resume | |
698 | * interfaces to suspend the nonstop clocksource when system suspends. | |
699 | */ | |
700 | if (cs->suspend || cs->resume) { | |
701 | pr_warn("Nonstop clocksource %s should not supply suspend/resume interfaces\n", | |
702 | cs->name); | |
703 | } | |
704 | ||
705 | /* Pick the best rating. */ | |
706 | if (!suspend_clocksource || cs->rating > suspend_clocksource->rating) | |
707 | suspend_clocksource = cs; | |
708 | } | |
709 | ||
710 | /** | |
711 | * clocksource_suspend_select - Select the best clocksource for suspend timing | |
712 | * @fallback: if select a fallback clocksource | |
713 | */ | |
714 | static void clocksource_suspend_select(bool fallback) | |
715 | { | |
716 | struct clocksource *cs, *old_suspend; | |
717 | ||
718 | old_suspend = suspend_clocksource; | |
719 | if (fallback) | |
720 | suspend_clocksource = NULL; | |
721 | ||
722 | list_for_each_entry(cs, &clocksource_list, list) { | |
723 | /* Skip current if we were requested for a fallback. */ | |
724 | if (fallback && cs == old_suspend) | |
725 | continue; | |
726 | ||
727 | __clocksource_suspend_select(cs); | |
728 | } | |
729 | } | |
730 | ||
731 | /** | |
732 | * clocksource_start_suspend_timing - Start measuring the suspend timing | |
733 | * @cs: current clocksource from timekeeping | |
734 | * @start_cycles: current cycles from timekeeping | |
735 | * | |
736 | * This function will save the start cycle values of suspend timer to calculate | |
737 | * the suspend time when resuming system. | |
738 | * | |
739 | * This function is called late in the suspend process from timekeeping_suspend(), | |
4bf07f65 | 740 | * that means processes are frozen, non-boot cpus and interrupts are disabled |
39232ed5 BW |
741 | * now. It is therefore possible to start the suspend timer without taking the |
742 | * clocksource mutex. | |
743 | */ | |
744 | void clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles) | |
745 | { | |
746 | if (!suspend_clocksource) | |
747 | return; | |
748 | ||
749 | /* | |
750 | * If current clocksource is the suspend timer, we should use the | |
751 | * tkr_mono.cycle_last value as suspend_start to avoid same reading | |
752 | * from suspend timer. | |
753 | */ | |
754 | if (clocksource_is_suspend(cs)) { | |
755 | suspend_start = start_cycles; | |
756 | return; | |
757 | } | |
758 | ||
759 | if (suspend_clocksource->enable && | |
760 | suspend_clocksource->enable(suspend_clocksource)) { | |
761 | pr_warn_once("Failed to enable the non-suspend-able clocksource.\n"); | |
762 | return; | |
763 | } | |
764 | ||
765 | suspend_start = suspend_clocksource->read(suspend_clocksource); | |
766 | } | |
767 | ||
768 | /** | |
769 | * clocksource_stop_suspend_timing - Stop measuring the suspend timing | |
770 | * @cs: current clocksource from timekeeping | |
771 | * @cycle_now: current cycles from timekeeping | |
772 | * | |
773 | * This function will calculate the suspend time from suspend timer. | |
774 | * | |
775 | * Returns nanoseconds since suspend started, 0 if no usable suspend clocksource. | |
776 | * | |
777 | * This function is called early in the resume process from timekeeping_resume(), | |
778 | * that means there is only one cpu, no processes are running and the interrupts | |
779 | * are disabled. It is therefore possible to stop the suspend timer without | |
780 | * taking the clocksource mutex. | |
781 | */ | |
782 | u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 cycle_now) | |
783 | { | |
784 | u64 now, delta, nsec = 0; | |
785 | ||
786 | if (!suspend_clocksource) | |
787 | return 0; | |
788 | ||
789 | /* | |
790 | * If current clocksource is the suspend timer, we should use the | |
791 | * tkr_mono.cycle_last value from timekeeping as current cycle to | |
792 | * avoid same reading from suspend timer. | |
793 | */ | |
794 | if (clocksource_is_suspend(cs)) | |
795 | now = cycle_now; | |
796 | else | |
797 | now = suspend_clocksource->read(suspend_clocksource); | |
798 | ||
799 | if (now > suspend_start) { | |
800 | delta = clocksource_delta(now, suspend_start, | |
801 | suspend_clocksource->mask); | |
802 | nsec = mul_u64_u32_shr(delta, suspend_clocksource->mult, | |
803 | suspend_clocksource->shift); | |
804 | } | |
805 | ||
806 | /* | |
807 | * Disable the suspend timer to save power if current clocksource is | |
808 | * not the suspend timer. | |
809 | */ | |
810 | if (!clocksource_is_suspend(cs) && suspend_clocksource->disable) | |
811 | suspend_clocksource->disable(suspend_clocksource); | |
812 | ||
813 | return nsec; | |
814 | } | |
815 | ||
c54a42b1 MD |
816 | /** |
817 | * clocksource_suspend - suspend the clocksource(s) | |
818 | */ | |
819 | void clocksource_suspend(void) | |
820 | { | |
821 | struct clocksource *cs; | |
822 | ||
823 | list_for_each_entry_reverse(cs, &clocksource_list, list) | |
824 | if (cs->suspend) | |
825 | cs->suspend(cs); | |
826 | } | |
827 | ||
b52f52a0 TG |
828 | /** |
829 | * clocksource_resume - resume the clocksource(s) | |
830 | */ | |
831 | void clocksource_resume(void) | |
832 | { | |
2e197586 | 833 | struct clocksource *cs; |
b52f52a0 | 834 | |
75c5158f | 835 | list_for_each_entry(cs, &clocksource_list, list) |
b52f52a0 | 836 | if (cs->resume) |
17622339 | 837 | cs->resume(cs); |
b52f52a0 TG |
838 | |
839 | clocksource_resume_watchdog(); | |
b52f52a0 TG |
840 | } |
841 | ||
7c3078b6 JW |
842 | /** |
843 | * clocksource_touch_watchdog - Update watchdog | |
844 | * | |
845 | * Update the watchdog after exception contexts such as kgdb so as not | |
7b7422a5 TG |
846 | * to incorrectly trip the watchdog. This might fail when the kernel |
847 | * was stopped in code which holds watchdog_lock. | |
7c3078b6 JW |
848 | */ |
849 | void clocksource_touch_watchdog(void) | |
850 | { | |
851 | clocksource_resume_watchdog(); | |
852 | } | |
853 | ||
d65670a7 JS |
854 | /** |
855 | * clocksource_max_adjustment- Returns max adjustment amount | |
856 | * @cs: Pointer to clocksource | |
857 | * | |
858 | */ | |
859 | static u32 clocksource_max_adjustment(struct clocksource *cs) | |
860 | { | |
861 | u64 ret; | |
862 | /* | |
88b28adf | 863 | * We won't try to correct for more than 11% adjustments (110,000 ppm), |
d65670a7 JS |
864 | */ |
865 | ret = (u64)cs->mult * 11; | |
866 | do_div(ret,100); | |
867 | return (u32)ret; | |
868 | } | |
869 | ||
98962465 | 870 | /** |
87d8b9eb SB |
871 | * clocks_calc_max_nsecs - Returns maximum nanoseconds that can be converted |
872 | * @mult: cycle to nanosecond multiplier | |
873 | * @shift: cycle to nanosecond divisor (power of two) | |
874 | * @maxadj: maximum adjustment value to mult (~11%) | |
875 | * @mask: bitmask for two's complement subtraction of non 64 bit counters | |
fb82fe2f JS |
876 | * @max_cyc: maximum cycle value before potential overflow (does not include |
877 | * any safety margin) | |
362fde04 | 878 | * |
8e56f33f JS |
879 | * NOTE: This function includes a safety margin of 50%, in other words, we |
880 | * return half the number of nanoseconds the hardware counter can technically | |
881 | * cover. This is done so that we can potentially detect problems caused by | |
882 | * delayed timers or bad hardware, which might result in time intervals that | |
571af55a | 883 | * are larger than what the math used can handle without overflows. |
98962465 | 884 | */ |
fb82fe2f | 885 | u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cyc) |
98962465 JH |
886 | { |
887 | u64 max_nsecs, max_cycles; | |
888 | ||
889 | /* | |
890 | * Calculate the maximum number of cycles that we can pass to the | |
6086e346 | 891 | * cyc2ns() function without overflowing a 64-bit result. |
98962465 | 892 | */ |
6086e346 JS |
893 | max_cycles = ULLONG_MAX; |
894 | do_div(max_cycles, mult+maxadj); | |
98962465 JH |
895 | |
896 | /* | |
897 | * The actual maximum number of cycles we can defer the clocksource is | |
87d8b9eb | 898 | * determined by the minimum of max_cycles and mask. |
d65670a7 JS |
899 | * Note: Here we subtract the maxadj to make sure we don't sleep for |
900 | * too long if there's a large negative adjustment. | |
98962465 | 901 | */ |
87d8b9eb SB |
902 | max_cycles = min(max_cycles, mask); |
903 | max_nsecs = clocksource_cyc2ns(max_cycles, mult - maxadj, shift); | |
904 | ||
fb82fe2f JS |
905 | /* return the max_cycles value as well if requested */ |
906 | if (max_cyc) | |
907 | *max_cyc = max_cycles; | |
908 | ||
362fde04 JS |
909 | /* Return 50% of the actual maximum, so we can detect bad values */ |
910 | max_nsecs >>= 1; | |
911 | ||
87d8b9eb SB |
912 | return max_nsecs; |
913 | } | |
914 | ||
915 | /** | |
fb82fe2f JS |
916 | * clocksource_update_max_deferment - Updates the clocksource max_idle_ns & max_cycles |
917 | * @cs: Pointer to clocksource to be updated | |
87d8b9eb SB |
918 | * |
919 | */ | |
fb82fe2f | 920 | static inline void clocksource_update_max_deferment(struct clocksource *cs) |
87d8b9eb | 921 | { |
fb82fe2f JS |
922 | cs->max_idle_ns = clocks_calc_max_nsecs(cs->mult, cs->shift, |
923 | cs->maxadj, cs->mask, | |
924 | &cs->max_cycles); | |
98962465 JH |
925 | } |
926 | ||
f5a2e343 | 927 | static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur) |
5d33b883 TG |
928 | { |
929 | struct clocksource *cs; | |
930 | ||
931 | if (!finished_booting || list_empty(&clocksource_list)) | |
932 | return NULL; | |
933 | ||
934 | /* | |
935 | * We pick the clocksource with the highest rating. If oneshot | |
936 | * mode is active, we pick the highres valid clocksource with | |
937 | * the best rating. | |
938 | */ | |
939 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
940 | if (skipcur && cs == curr_clocksource) |
941 | continue; | |
5d33b883 TG |
942 | if (oneshot && !(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES)) |
943 | continue; | |
944 | return cs; | |
945 | } | |
946 | return NULL; | |
947 | } | |
948 | ||
f5a2e343 | 949 | static void __clocksource_select(bool skipcur) |
734efb46 | 950 | { |
5d33b883 | 951 | bool oneshot = tick_oneshot_mode_active(); |
f1b82746 | 952 | struct clocksource *best, *cs; |
5d8b34fd | 953 | |
5d33b883 | 954 | /* Find the best suitable clocksource */ |
f5a2e343 | 955 | best = clocksource_find_best(oneshot, skipcur); |
5d33b883 | 956 | if (!best) |
f1b82746 | 957 | return; |
5d33b883 | 958 | |
7f852afe BW |
959 | if (!strlen(override_name)) |
960 | goto found; | |
961 | ||
f1b82746 MS |
962 | /* Check for the override clocksource. */ |
963 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
964 | if (skipcur && cs == curr_clocksource) |
965 | continue; | |
f1b82746 MS |
966 | if (strcmp(cs->name, override_name) != 0) |
967 | continue; | |
968 | /* | |
969 | * Check to make sure we don't switch to a non-highres | |
970 | * capable clocksource if the tick code is in oneshot | |
971 | * mode (highres or nohz) | |
972 | */ | |
5d33b883 | 973 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && oneshot) { |
f1b82746 | 974 | /* Override clocksource cannot be used. */ |
36374583 KW |
975 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
976 | pr_warn("Override clocksource %s is unstable and not HRT compatible - cannot switch while in HRT/NOHZ mode\n", | |
977 | cs->name); | |
978 | override_name[0] = 0; | |
979 | } else { | |
980 | /* | |
981 | * The override cannot be currently verified. | |
982 | * Deferring to let the watchdog check. | |
983 | */ | |
984 | pr_info("Override clocksource %s is not currently HRT compatible - deferring\n", | |
985 | cs->name); | |
986 | } | |
f1b82746 MS |
987 | } else |
988 | /* Override clocksource can be used. */ | |
989 | best = cs; | |
990 | break; | |
991 | } | |
ba919d1c | 992 | |
7f852afe | 993 | found: |
ba919d1c TG |
994 | if (curr_clocksource != best && !timekeeping_notify(best)) { |
995 | pr_info("Switched to clocksource %s\n", best->name); | |
75c5158f | 996 | curr_clocksource = best; |
75c5158f | 997 | } |
f1b82746 | 998 | } |
734efb46 | 999 | |
f5a2e343 TG |
1000 | /** |
1001 | * clocksource_select - Select the best clocksource available | |
1002 | * | |
1003 | * Private function. Must hold clocksource_mutex when called. | |
1004 | * | |
1005 | * Select the clocksource with the best rating, or the clocksource, | |
1006 | * which is selected by userspace override. | |
1007 | */ | |
1008 | static void clocksource_select(void) | |
1009 | { | |
cfed432d | 1010 | __clocksource_select(false); |
f5a2e343 TG |
1011 | } |
1012 | ||
7eaeb343 TG |
1013 | static void clocksource_select_fallback(void) |
1014 | { | |
cfed432d | 1015 | __clocksource_select(true); |
7eaeb343 TG |
1016 | } |
1017 | ||
75c5158f MS |
1018 | /* |
1019 | * clocksource_done_booting - Called near the end of core bootup | |
1020 | * | |
1021 | * Hack to avoid lots of clocksource churn at boot time. | |
1022 | * We use fs_initcall because we want this to start before | |
1023 | * device_initcall but after subsys_initcall. | |
1024 | */ | |
1025 | static int __init clocksource_done_booting(void) | |
1026 | { | |
ad6759fb | 1027 | mutex_lock(&clocksource_mutex); |
1028 | curr_clocksource = clocksource_default_clock(); | |
75c5158f | 1029 | finished_booting = 1; |
54a6bc0b TG |
1030 | /* |
1031 | * Run the watchdog first to eliminate unstable clock sources | |
1032 | */ | |
e2c631ba | 1033 | __clocksource_watchdog_kthread(); |
75c5158f | 1034 | clocksource_select(); |
e6c73305 | 1035 | mutex_unlock(&clocksource_mutex); |
75c5158f MS |
1036 | return 0; |
1037 | } | |
1038 | fs_initcall(clocksource_done_booting); | |
1039 | ||
92c7e002 TG |
1040 | /* |
1041 | * Enqueue the clocksource sorted by rating | |
734efb46 | 1042 | */ |
f1b82746 | 1043 | static void clocksource_enqueue(struct clocksource *cs) |
734efb46 | 1044 | { |
f1b82746 MS |
1045 | struct list_head *entry = &clocksource_list; |
1046 | struct clocksource *tmp; | |
92c7e002 | 1047 | |
0fb71d34 | 1048 | list_for_each_entry(tmp, &clocksource_list, list) { |
92c7e002 | 1049 | /* Keep track of the place, where to insert */ |
0fb71d34 MH |
1050 | if (tmp->rating < cs->rating) |
1051 | break; | |
1052 | entry = &tmp->list; | |
1053 | } | |
f1b82746 | 1054 | list_add(&cs->list, entry); |
734efb46 | 1055 | } |
1056 | ||
d7e81c26 | 1057 | /** |
fba9e072 | 1058 | * __clocksource_update_freq_scale - Used update clocksource with new freq |
b1b73d09 | 1059 | * @cs: clocksource to be registered |
d7e81c26 JS |
1060 | * @scale: Scale factor multiplied against freq to get clocksource hz |
1061 | * @freq: clocksource frequency (cycles per second) divided by scale | |
1062 | * | |
852db46d | 1063 | * This should only be called from the clocksource->enable() method. |
d7e81c26 JS |
1064 | * |
1065 | * This *SHOULD NOT* be called directly! Please use the | |
fba9e072 JS |
1066 | * __clocksource_update_freq_hz() or __clocksource_update_freq_khz() helper |
1067 | * functions. | |
d7e81c26 | 1068 | */ |
fba9e072 | 1069 | void __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq) |
d7e81c26 | 1070 | { |
c0e299b1 | 1071 | u64 sec; |
f8935983 | 1072 | |
d7e81c26 | 1073 | /* |
f8935983 JS |
1074 | * Default clocksources are *special* and self-define their mult/shift. |
1075 | * But, you're not special, so you should specify a freq value. | |
d7e81c26 | 1076 | */ |
f8935983 JS |
1077 | if (freq) { |
1078 | /* | |
1079 | * Calc the maximum number of seconds which we can run before | |
1080 | * wrapping around. For clocksources which have a mask > 32-bit | |
1081 | * we need to limit the max sleep time to have a good | |
1082 | * conversion precision. 10 minutes is still a reasonable | |
1083 | * amount. That results in a shift value of 24 for a | |
1084 | * clocksource with mask >= 40-bit and f >= 4GHz. That maps to | |
1085 | * ~ 0.06ppm granularity for NTP. | |
1086 | */ | |
1087 | sec = cs->mask; | |
1088 | do_div(sec, freq); | |
1089 | do_div(sec, scale); | |
1090 | if (!sec) | |
1091 | sec = 1; | |
1092 | else if (sec > 600 && cs->mask > UINT_MAX) | |
1093 | sec = 600; | |
1094 | ||
1095 | clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, | |
1096 | NSEC_PER_SEC / scale, sec * scale); | |
1097 | } | |
2e27e793 PM |
1098 | |
1099 | /* | |
1100 | * If the uncertainty margin is not specified, calculate it. | |
1101 | * If both scale and freq are non-zero, calculate the clock | |
1102 | * period, but bound below at 2*WATCHDOG_MAX_SKEW. However, | |
1103 | * if either of scale or freq is zero, be very conservative and | |
1104 | * take the tens-of-milliseconds WATCHDOG_THRESHOLD value for the | |
1105 | * uncertainty margin. Allow stupidly small uncertainty margins | |
1106 | * to be specified by the caller for testing purposes, but warn | |
1107 | * to discourage production use of this capability. | |
1108 | */ | |
1109 | if (scale && freq && !cs->uncertainty_margin) { | |
1110 | cs->uncertainty_margin = NSEC_PER_SEC / (scale * freq); | |
1111 | if (cs->uncertainty_margin < 2 * WATCHDOG_MAX_SKEW) | |
1112 | cs->uncertainty_margin = 2 * WATCHDOG_MAX_SKEW; | |
1113 | } else if (!cs->uncertainty_margin) { | |
1114 | cs->uncertainty_margin = WATCHDOG_THRESHOLD; | |
1115 | } | |
1116 | WARN_ON_ONCE(cs->uncertainty_margin < 2 * WATCHDOG_MAX_SKEW); | |
1117 | ||
d65670a7 | 1118 | /* |
362fde04 JS |
1119 | * Ensure clocksources that have large 'mult' values don't overflow |
1120 | * when adjusted. | |
d65670a7 JS |
1121 | */ |
1122 | cs->maxadj = clocksource_max_adjustment(cs); | |
f8935983 JS |
1123 | while (freq && ((cs->mult + cs->maxadj < cs->mult) |
1124 | || (cs->mult - cs->maxadj > cs->mult))) { | |
d65670a7 JS |
1125 | cs->mult >>= 1; |
1126 | cs->shift--; | |
1127 | cs->maxadj = clocksource_max_adjustment(cs); | |
1128 | } | |
1129 | ||
f8935983 JS |
1130 | /* |
1131 | * Only warn for *special* clocksources that self-define | |
1132 | * their mult/shift values and don't specify a freq. | |
1133 | */ | |
1134 | WARN_ONCE(cs->mult + cs->maxadj < cs->mult, | |
1135 | "timekeeping: Clocksource %s might overflow on 11%% adjustment\n", | |
1136 | cs->name); | |
1137 | ||
fb82fe2f | 1138 | clocksource_update_max_deferment(cs); |
8cc8c525 | 1139 | |
45bbfe64 JP |
1140 | pr_info("%s: mask: 0x%llx max_cycles: 0x%llx, max_idle_ns: %lld ns\n", |
1141 | cs->name, cs->mask, cs->max_cycles, cs->max_idle_ns); | |
852db46d | 1142 | } |
fba9e072 | 1143 | EXPORT_SYMBOL_GPL(__clocksource_update_freq_scale); |
852db46d JS |
1144 | |
1145 | /** | |
1146 | * __clocksource_register_scale - Used to install new clocksources | |
b1b73d09 | 1147 | * @cs: clocksource to be registered |
852db46d JS |
1148 | * @scale: Scale factor multiplied against freq to get clocksource hz |
1149 | * @freq: clocksource frequency (cycles per second) divided by scale | |
1150 | * | |
1151 | * Returns -EBUSY if registration fails, zero otherwise. | |
1152 | * | |
1153 | * This *SHOULD NOT* be called directly! Please use the | |
1154 | * clocksource_register_hz() or clocksource_register_khz helper functions. | |
1155 | */ | |
1156 | int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) | |
1157 | { | |
2aae7bcf | 1158 | unsigned long flags; |
852db46d | 1159 | |
d67f34c1 TG |
1160 | clocksource_arch_init(cs); |
1161 | ||
b2c67cbe TG |
1162 | if (WARN_ON_ONCE((unsigned int)cs->id >= CSID_MAX)) |
1163 | cs->id = CSID_GENERIC; | |
5d51bee7 TG |
1164 | if (cs->vdso_clock_mode < 0 || |
1165 | cs->vdso_clock_mode >= VDSO_CLOCKMODE_MAX) { | |
1166 | pr_warn("clocksource %s registered with invalid VDSO mode %d. Disabling VDSO support.\n", | |
1167 | cs->name, cs->vdso_clock_mode); | |
1168 | cs->vdso_clock_mode = VDSO_CLOCKMODE_NONE; | |
1169 | } | |
5d51bee7 | 1170 | |
b595076a | 1171 | /* Initialize mult/shift and max_idle_ns */ |
fba9e072 | 1172 | __clocksource_update_freq_scale(cs, scale, freq); |
d7e81c26 | 1173 | |
be278e98 | 1174 | /* Add clocksource to the clocksource list */ |
d7e81c26 | 1175 | mutex_lock(&clocksource_mutex); |
2aae7bcf PZ |
1176 | |
1177 | clocksource_watchdog_lock(&flags); | |
d7e81c26 | 1178 | clocksource_enqueue(cs); |
d7e81c26 | 1179 | clocksource_enqueue_watchdog(cs); |
2aae7bcf PZ |
1180 | clocksource_watchdog_unlock(&flags); |
1181 | ||
e05b2efb | 1182 | clocksource_select(); |
bbf66d89 | 1183 | clocksource_select_watchdog(false); |
39232ed5 | 1184 | __clocksource_suspend_select(cs); |
d7e81c26 JS |
1185 | mutex_unlock(&clocksource_mutex); |
1186 | return 0; | |
1187 | } | |
1188 | EXPORT_SYMBOL_GPL(__clocksource_register_scale); | |
1189 | ||
d0981a1b TG |
1190 | static void __clocksource_change_rating(struct clocksource *cs, int rating) |
1191 | { | |
1192 | list_del(&cs->list); | |
1193 | cs->rating = rating; | |
1194 | clocksource_enqueue(cs); | |
d0981a1b TG |
1195 | } |
1196 | ||
734efb46 | 1197 | /** |
92c7e002 | 1198 | * clocksource_change_rating - Change the rating of a registered clocksource |
b1b73d09 KK |
1199 | * @cs: clocksource to be changed |
1200 | * @rating: new rating | |
734efb46 | 1201 | */ |
92c7e002 | 1202 | void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb46 | 1203 | { |
2aae7bcf PZ |
1204 | unsigned long flags; |
1205 | ||
75c5158f | 1206 | mutex_lock(&clocksource_mutex); |
2aae7bcf | 1207 | clocksource_watchdog_lock(&flags); |
d0981a1b | 1208 | __clocksource_change_rating(cs, rating); |
2aae7bcf PZ |
1209 | clocksource_watchdog_unlock(&flags); |
1210 | ||
332962f2 | 1211 | clocksource_select(); |
bbf66d89 | 1212 | clocksource_select_watchdog(false); |
39232ed5 | 1213 | clocksource_suspend_select(false); |
75c5158f | 1214 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1215 | } |
fb63a0eb | 1216 | EXPORT_SYMBOL(clocksource_change_rating); |
734efb46 | 1217 | |
7eaeb343 TG |
1218 | /* |
1219 | * Unbind clocksource @cs. Called with clocksource_mutex held | |
1220 | */ | |
1221 | static int clocksource_unbind(struct clocksource *cs) | |
1222 | { | |
2aae7bcf PZ |
1223 | unsigned long flags; |
1224 | ||
bbf66d89 VK |
1225 | if (clocksource_is_watchdog(cs)) { |
1226 | /* Select and try to install a replacement watchdog. */ | |
1227 | clocksource_select_watchdog(true); | |
1228 | if (clocksource_is_watchdog(cs)) | |
1229 | return -EBUSY; | |
1230 | } | |
7eaeb343 TG |
1231 | |
1232 | if (cs == curr_clocksource) { | |
1233 | /* Select and try to install a replacement clock source */ | |
1234 | clocksource_select_fallback(); | |
1235 | if (curr_clocksource == cs) | |
1236 | return -EBUSY; | |
1237 | } | |
2aae7bcf | 1238 | |
39232ed5 BW |
1239 | if (clocksource_is_suspend(cs)) { |
1240 | /* | |
1241 | * Select and try to install a replacement suspend clocksource. | |
1242 | * If no replacement suspend clocksource, we will just let the | |
1243 | * clocksource go and have no suspend clocksource. | |
1244 | */ | |
1245 | clocksource_suspend_select(true); | |
1246 | } | |
1247 | ||
2aae7bcf | 1248 | clocksource_watchdog_lock(&flags); |
7eaeb343 TG |
1249 | clocksource_dequeue_watchdog(cs); |
1250 | list_del_init(&cs->list); | |
2aae7bcf PZ |
1251 | clocksource_watchdog_unlock(&flags); |
1252 | ||
7eaeb343 TG |
1253 | return 0; |
1254 | } | |
1255 | ||
4713e22c TG |
1256 | /** |
1257 | * clocksource_unregister - remove a registered clocksource | |
b1b73d09 | 1258 | * @cs: clocksource to be unregistered |
4713e22c | 1259 | */ |
a89c7edb | 1260 | int clocksource_unregister(struct clocksource *cs) |
4713e22c | 1261 | { |
a89c7edb TG |
1262 | int ret = 0; |
1263 | ||
75c5158f | 1264 | mutex_lock(&clocksource_mutex); |
a89c7edb TG |
1265 | if (!list_empty(&cs->list)) |
1266 | ret = clocksource_unbind(cs); | |
75c5158f | 1267 | mutex_unlock(&clocksource_mutex); |
a89c7edb | 1268 | return ret; |
4713e22c | 1269 | } |
fb63a0eb | 1270 | EXPORT_SYMBOL(clocksource_unregister); |
4713e22c | 1271 | |
2b013700 | 1272 | #ifdef CONFIG_SYSFS |
734efb46 | 1273 | /** |
e87821d1 | 1274 | * current_clocksource_show - sysfs interface for current clocksource |
734efb46 | 1275 | * @dev: unused |
b1b73d09 | 1276 | * @attr: unused |
734efb46 | 1277 | * @buf: char buffer to be filled with clocksource list |
1278 | * | |
1279 | * Provides sysfs interface for listing current clocksource. | |
1280 | */ | |
e87821d1 BW |
1281 | static ssize_t current_clocksource_show(struct device *dev, |
1282 | struct device_attribute *attr, | |
1283 | char *buf) | |
734efb46 | 1284 | { |
5e2cb101 | 1285 | ssize_t count = 0; |
734efb46 | 1286 | |
75c5158f | 1287 | mutex_lock(&clocksource_mutex); |
5e2cb101 | 1288 | count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); |
75c5158f | 1289 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1290 | |
5e2cb101 | 1291 | return count; |
734efb46 | 1292 | } |
1293 | ||
891292a7 | 1294 | ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt) |
29b54078 TG |
1295 | { |
1296 | size_t ret = cnt; | |
1297 | ||
1298 | /* strings from sysfs write are not 0 terminated! */ | |
1299 | if (!cnt || cnt >= CS_NAME_LEN) | |
1300 | return -EINVAL; | |
1301 | ||
1302 | /* strip of \n: */ | |
1303 | if (buf[cnt-1] == '\n') | |
1304 | cnt--; | |
1305 | if (cnt > 0) | |
1306 | memcpy(dst, buf, cnt); | |
1307 | dst[cnt] = 0; | |
1308 | return ret; | |
1309 | } | |
1310 | ||
734efb46 | 1311 | /** |
e87821d1 | 1312 | * current_clocksource_store - interface for manually overriding clocksource |
734efb46 | 1313 | * @dev: unused |
b1b73d09 | 1314 | * @attr: unused |
734efb46 | 1315 | * @buf: name of override clocksource |
1316 | * @count: length of buffer | |
1317 | * | |
1318 | * Takes input from sysfs interface for manually overriding the default | |
b71a8eb0 | 1319 | * clocksource selection. |
734efb46 | 1320 | */ |
e87821d1 BW |
1321 | static ssize_t current_clocksource_store(struct device *dev, |
1322 | struct device_attribute *attr, | |
1323 | const char *buf, size_t count) | |
734efb46 | 1324 | { |
233bcb41 | 1325 | ssize_t ret; |
734efb46 | 1326 | |
75c5158f | 1327 | mutex_lock(&clocksource_mutex); |
734efb46 | 1328 | |
03e13cf5 | 1329 | ret = sysfs_get_uname(buf, override_name, count); |
29b54078 TG |
1330 | if (ret >= 0) |
1331 | clocksource_select(); | |
734efb46 | 1332 | |
75c5158f | 1333 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1334 | |
1335 | return ret; | |
1336 | } | |
e87821d1 | 1337 | static DEVICE_ATTR_RW(current_clocksource); |
734efb46 | 1338 | |
7eaeb343 | 1339 | /** |
e87821d1 | 1340 | * unbind_clocksource_store - interface for manually unbinding clocksource |
7eaeb343 TG |
1341 | * @dev: unused |
1342 | * @attr: unused | |
1343 | * @buf: unused | |
1344 | * @count: length of buffer | |
1345 | * | |
1346 | * Takes input from sysfs interface for manually unbinding a clocksource. | |
1347 | */ | |
e87821d1 | 1348 | static ssize_t unbind_clocksource_store(struct device *dev, |
7eaeb343 TG |
1349 | struct device_attribute *attr, |
1350 | const char *buf, size_t count) | |
1351 | { | |
1352 | struct clocksource *cs; | |
1353 | char name[CS_NAME_LEN]; | |
233bcb41 | 1354 | ssize_t ret; |
7eaeb343 | 1355 | |
03e13cf5 | 1356 | ret = sysfs_get_uname(buf, name, count); |
7eaeb343 TG |
1357 | if (ret < 0) |
1358 | return ret; | |
1359 | ||
1360 | ret = -ENODEV; | |
1361 | mutex_lock(&clocksource_mutex); | |
1362 | list_for_each_entry(cs, &clocksource_list, list) { | |
1363 | if (strcmp(cs->name, name)) | |
1364 | continue; | |
1365 | ret = clocksource_unbind(cs); | |
1366 | break; | |
1367 | } | |
1368 | mutex_unlock(&clocksource_mutex); | |
1369 | ||
1370 | return ret ? ret : count; | |
1371 | } | |
e87821d1 | 1372 | static DEVICE_ATTR_WO(unbind_clocksource); |
7eaeb343 | 1373 | |
734efb46 | 1374 | /** |
e87821d1 | 1375 | * available_clocksource_show - sysfs interface for listing clocksource |
734efb46 | 1376 | * @dev: unused |
b1b73d09 | 1377 | * @attr: unused |
734efb46 | 1378 | * @buf: char buffer to be filled with clocksource list |
1379 | * | |
1380 | * Provides sysfs interface for listing registered clocksources | |
1381 | */ | |
e87821d1 BW |
1382 | static ssize_t available_clocksource_show(struct device *dev, |
1383 | struct device_attribute *attr, | |
1384 | char *buf) | |
734efb46 | 1385 | { |
2e197586 | 1386 | struct clocksource *src; |
5e2cb101 | 1387 | ssize_t count = 0; |
734efb46 | 1388 | |
75c5158f | 1389 | mutex_lock(&clocksource_mutex); |
2e197586 | 1390 | list_for_each_entry(src, &clocksource_list, list) { |
cd6d95d8 TG |
1391 | /* |
1392 | * Don't show non-HRES clocksource if the tick code is | |
1393 | * in one shot mode (highres=on or nohz=on) | |
1394 | */ | |
1395 | if (!tick_oneshot_mode_active() || | |
1396 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) | |
3f68535a | 1397 | count += snprintf(buf + count, |
5e2cb101 MX |
1398 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), |
1399 | "%s ", src->name); | |
734efb46 | 1400 | } |
75c5158f | 1401 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1402 | |
5e2cb101 MX |
1403 | count += snprintf(buf + count, |
1404 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); | |
734efb46 | 1405 | |
5e2cb101 | 1406 | return count; |
734efb46 | 1407 | } |
e87821d1 | 1408 | static DEVICE_ATTR_RO(available_clocksource); |
734efb46 | 1409 | |
27263e8d BW |
1410 | static struct attribute *clocksource_attrs[] = { |
1411 | &dev_attr_current_clocksource.attr, | |
1412 | &dev_attr_unbind_clocksource.attr, | |
1413 | &dev_attr_available_clocksource.attr, | |
1414 | NULL | |
1415 | }; | |
1416 | ATTRIBUTE_GROUPS(clocksource); | |
1417 | ||
d369a5d8 | 1418 | static struct bus_type clocksource_subsys = { |
af5ca3f4 | 1419 | .name = "clocksource", |
d369a5d8 | 1420 | .dev_name = "clocksource", |
734efb46 | 1421 | }; |
1422 | ||
d369a5d8 | 1423 | static struct device device_clocksource = { |
734efb46 | 1424 | .id = 0, |
d369a5d8 | 1425 | .bus = &clocksource_subsys, |
27263e8d | 1426 | .groups = clocksource_groups, |
734efb46 | 1427 | }; |
1428 | ||
ad596171 | 1429 | static int __init init_clocksource_sysfs(void) |
734efb46 | 1430 | { |
d369a5d8 | 1431 | int error = subsys_system_register(&clocksource_subsys, NULL); |
734efb46 | 1432 | |
1433 | if (!error) | |
d369a5d8 | 1434 | error = device_register(&device_clocksource); |
27263e8d | 1435 | |
734efb46 | 1436 | return error; |
1437 | } | |
1438 | ||
1439 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 1440 | #endif /* CONFIG_SYSFS */ |
734efb46 | 1441 | |
1442 | /** | |
1443 | * boot_override_clocksource - boot clock override | |
1444 | * @str: override name | |
1445 | * | |
1446 | * Takes a clocksource= boot argument and uses it | |
1447 | * as the clocksource override name. | |
1448 | */ | |
1449 | static int __init boot_override_clocksource(char* str) | |
1450 | { | |
75c5158f | 1451 | mutex_lock(&clocksource_mutex); |
734efb46 | 1452 | if (str) |
1453 | strlcpy(override_name, str, sizeof(override_name)); | |
75c5158f | 1454 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1455 | return 1; |
1456 | } | |
1457 | ||
1458 | __setup("clocksource=", boot_override_clocksource); | |
1459 | ||
1460 | /** | |
1461 | * boot_override_clock - Compatibility layer for deprecated boot option | |
1462 | * @str: override name | |
1463 | * | |
1464 | * DEPRECATED! Takes a clock= boot argument and uses it | |
1465 | * as the clocksource override name | |
1466 | */ | |
1467 | static int __init boot_override_clock(char* str) | |
1468 | { | |
5d0cf410 | 1469 | if (!strcmp(str, "pmtmr")) { |
45bbfe64 | 1470 | pr_warn("clock=pmtmr is deprecated - use clocksource=acpi_pm\n"); |
5d0cf410 | 1471 | return boot_override_clocksource("acpi_pm"); |
1472 | } | |
45bbfe64 | 1473 | pr_warn("clock= boot option is deprecated - use clocksource=xyz\n"); |
734efb46 | 1474 | return boot_override_clocksource(str); |
1475 | } | |
1476 | ||
1477 | __setup("clock=", boot_override_clock); |