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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 | |
c37e85c1 PM |
98 | /* |
99 | * Interval: 0.5sec. | |
100 | */ | |
101 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
102 | ||
2e27e793 PM |
103 | /* |
104 | * Threshold: 0.0312s, when doubled: 0.0625s. | |
105 | * Also a default for cs->uncertainty_margin when registering clocks. | |
106 | */ | |
107 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 5) | |
108 | ||
109 | /* | |
110 | * Maximum permissible delay between two readouts of the watchdog | |
111 | * clocksource surrounding a read of the clocksource being validated. | |
112 | * This delay could be due to SMIs, NMIs, or to VCPU preemptions. Used as | |
113 | * a lower bound for cs->uncertainty_margin values when registering clocks. | |
c37e85c1 PM |
114 | * |
115 | * The default of 500 parts per million is based on NTP's limits. | |
116 | * If a clocksource is good enough for NTP, it is good enough for us! | |
2e27e793 | 117 | */ |
fc153c1c WL |
118 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG_MAX_SKEW_US |
119 | #define MAX_SKEW_USEC CONFIG_CLOCKSOURCE_WATCHDOG_MAX_SKEW_US | |
120 | #else | |
c37e85c1 | 121 | #define MAX_SKEW_USEC (125 * WATCHDOG_INTERVAL / HZ) |
fc153c1c WL |
122 | #endif |
123 | ||
124 | #define WATCHDOG_MAX_SKEW (MAX_SKEW_USEC * NSEC_PER_USEC) | |
2e27e793 | 125 | |
5d8b34fd | 126 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
f79e0258 | 127 | static void clocksource_watchdog_work(struct work_struct *work); |
332962f2 | 128 | static void clocksource_select(void); |
f79e0258 | 129 | |
5d8b34fd TG |
130 | static LIST_HEAD(watchdog_list); |
131 | static struct clocksource *watchdog; | |
132 | static struct timer_list watchdog_timer; | |
f79e0258 | 133 | static DECLARE_WORK(watchdog_work, clocksource_watchdog_work); |
5d8b34fd | 134 | static DEFINE_SPINLOCK(watchdog_lock); |
fb63a0eb | 135 | static int watchdog_running; |
9fb60336 | 136 | static atomic_t watchdog_reset_pending; |
b52f52a0 | 137 | |
0f48b41f | 138 | static inline void clocksource_watchdog_lock(unsigned long *flags) |
2aae7bcf PZ |
139 | { |
140 | spin_lock_irqsave(&watchdog_lock, *flags); | |
141 | } | |
142 | ||
0f48b41f | 143 | static inline void clocksource_watchdog_unlock(unsigned long *flags) |
2aae7bcf PZ |
144 | { |
145 | spin_unlock_irqrestore(&watchdog_lock, *flags); | |
146 | } | |
147 | ||
e2c631ba PZ |
148 | static int clocksource_watchdog_kthread(void *data); |
149 | static void __clocksource_change_rating(struct clocksource *cs, int rating); | |
150 | ||
e2c631ba PZ |
151 | static void clocksource_watchdog_work(struct work_struct *work) |
152 | { | |
153 | /* | |
154 | * We cannot directly run clocksource_watchdog_kthread() here, because | |
155 | * clocksource_select() calls timekeeping_notify() which uses | |
156 | * stop_machine(). One cannot use stop_machine() from a workqueue() due | |
157 | * lock inversions wrt CPU hotplug. | |
158 | * | |
159 | * Also, we only ever run this work once or twice during the lifetime | |
160 | * of the kernel, so there is no point in creating a more permanent | |
161 | * kthread for this. | |
162 | * | |
163 | * If kthread_run fails the next watchdog scan over the | |
164 | * watchdog_list will find the unstable clock again. | |
165 | */ | |
166 | kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog"); | |
167 | } | |
168 | ||
7285dd7f | 169 | static void __clocksource_unstable(struct clocksource *cs) |
5d8b34fd | 170 | { |
5d8b34fd | 171 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); |
c55c87c8 | 172 | cs->flags |= CLOCK_SOURCE_UNSTABLE; |
12907fbb | 173 | |
cd2af07d | 174 | /* |
e2c631ba | 175 | * If the clocksource is registered clocksource_watchdog_kthread() will |
cd2af07d PZ |
176 | * re-rate and re-select. |
177 | */ | |
178 | if (list_empty(&cs->list)) { | |
179 | cs->rating = 0; | |
2aae7bcf | 180 | return; |
cd2af07d | 181 | } |
2aae7bcf | 182 | |
12907fbb TG |
183 | if (cs->mark_unstable) |
184 | cs->mark_unstable(cs); | |
185 | ||
e2c631ba | 186 | /* kick clocksource_watchdog_kthread() */ |
54a6bc0b TG |
187 | if (finished_booting) |
188 | schedule_work(&watchdog_work); | |
5d8b34fd TG |
189 | } |
190 | ||
7285dd7f TG |
191 | /** |
192 | * clocksource_mark_unstable - mark clocksource unstable via watchdog | |
193 | * @cs: clocksource to be marked unstable | |
194 | * | |
7dba33c6 | 195 | * This function is called by the x86 TSC code to mark clocksources as unstable; |
e2c631ba | 196 | * it defers demotion and re-selection to a kthread. |
7285dd7f TG |
197 | */ |
198 | void clocksource_mark_unstable(struct clocksource *cs) | |
199 | { | |
200 | unsigned long flags; | |
201 | ||
202 | spin_lock_irqsave(&watchdog_lock, flags); | |
203 | if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) { | |
2aae7bcf | 204 | if (!list_empty(&cs->list) && list_empty(&cs->wd_list)) |
7285dd7f TG |
205 | list_add(&cs->wd_list, &watchdog_list); |
206 | __clocksource_unstable(cs); | |
207 | } | |
208 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
209 | } | |
210 | ||
1a562067 | 211 | ulong max_cswd_read_retries = 2; |
db3a34e1 | 212 | module_param(max_cswd_read_retries, ulong, 0644); |
1253b9b8 | 213 | EXPORT_SYMBOL_GPL(max_cswd_read_retries); |
fa218f1c PM |
214 | static int verify_n_cpus = 8; |
215 | module_param(verify_n_cpus, int, 0644); | |
db3a34e1 | 216 | |
c86ff8c5 WL |
217 | enum wd_read_status { |
218 | WD_READ_SUCCESS, | |
219 | WD_READ_UNSTABLE, | |
220 | WD_READ_SKIP | |
221 | }; | |
222 | ||
223 | static enum wd_read_status cs_watchdog_read(struct clocksource *cs, u64 *csnow, u64 *wdnow) | |
db3a34e1 PM |
224 | { |
225 | unsigned int nretries; | |
c86ff8c5 WL |
226 | u64 wd_end, wd_end2, wd_delta; |
227 | int64_t wd_delay, wd_seq_delay; | |
db3a34e1 PM |
228 | |
229 | for (nretries = 0; nretries <= max_cswd_read_retries; nretries++) { | |
230 | local_irq_disable(); | |
231 | *wdnow = watchdog->read(watchdog); | |
232 | *csnow = cs->read(cs); | |
233 | wd_end = watchdog->read(watchdog); | |
c86ff8c5 | 234 | wd_end2 = watchdog->read(watchdog); |
db3a34e1 PM |
235 | local_irq_enable(); |
236 | ||
237 | wd_delta = clocksource_delta(wd_end, *wdnow, watchdog->mask); | |
238 | wd_delay = clocksource_cyc2ns(wd_delta, watchdog->mult, | |
239 | watchdog->shift); | |
240 | if (wd_delay <= WATCHDOG_MAX_SKEW) { | |
241 | if (nretries > 1 || nretries >= max_cswd_read_retries) { | |
242 | pr_warn("timekeeping watchdog on CPU%d: %s retried %d times before success\n", | |
243 | smp_processor_id(), watchdog->name, nretries); | |
244 | } | |
c86ff8c5 | 245 | return WD_READ_SUCCESS; |
db3a34e1 | 246 | } |
c86ff8c5 WL |
247 | |
248 | /* | |
249 | * Now compute delay in consecutive watchdog read to see if | |
250 | * there is too much external interferences that cause | |
251 | * significant delay in reading both clocksource and watchdog. | |
252 | * | |
253 | * If consecutive WD read-back delay > WATCHDOG_MAX_SKEW/2, | |
254 | * report system busy, reinit the watchdog and skip the current | |
255 | * watchdog test. | |
256 | */ | |
257 | wd_delta = clocksource_delta(wd_end2, wd_end, watchdog->mask); | |
258 | wd_seq_delay = clocksource_cyc2ns(wd_delta, watchdog->mult, watchdog->shift); | |
259 | if (wd_seq_delay > WATCHDOG_MAX_SKEW/2) | |
260 | goto skip_test; | |
db3a34e1 PM |
261 | } |
262 | ||
f092eb34 PM |
263 | pr_warn("timekeeping watchdog on CPU%d: wd-%s-wd excessive read-back delay of %lldns vs. limit of %ldns, wd-wd read-back delay only %lldns, attempt %d, marking %s unstable\n", |
264 | smp_processor_id(), cs->name, wd_delay, WATCHDOG_MAX_SKEW, wd_seq_delay, nretries, cs->name); | |
c86ff8c5 WL |
265 | return WD_READ_UNSTABLE; |
266 | ||
267 | skip_test: | |
268 | pr_info("timekeeping watchdog on CPU%d: %s wd-wd read-back delay of %lldns\n", | |
269 | smp_processor_id(), watchdog->name, wd_seq_delay); | |
270 | pr_info("wd-%s-wd read-back delay of %lldns, clock-skew test skipped!\n", | |
271 | cs->name, wd_delay); | |
272 | return WD_READ_SKIP; | |
db3a34e1 PM |
273 | } |
274 | ||
7560c02b PM |
275 | static u64 csnow_mid; |
276 | static cpumask_t cpus_ahead; | |
277 | static cpumask_t cpus_behind; | |
fa218f1c PM |
278 | static cpumask_t cpus_chosen; |
279 | ||
280 | static void clocksource_verify_choose_cpus(void) | |
281 | { | |
282 | int cpu, i, n = verify_n_cpus; | |
283 | ||
284 | if (n < 0) { | |
285 | /* Check all of the CPUs. */ | |
286 | cpumask_copy(&cpus_chosen, cpu_online_mask); | |
287 | cpumask_clear_cpu(smp_processor_id(), &cpus_chosen); | |
288 | return; | |
289 | } | |
290 | ||
291 | /* If no checking desired, or no other CPU to check, leave. */ | |
292 | cpumask_clear(&cpus_chosen); | |
293 | if (n == 0 || num_online_cpus() <= 1) | |
294 | return; | |
295 | ||
296 | /* Make sure to select at least one CPU other than the current CPU. */ | |
9b51d9d8 | 297 | cpu = cpumask_first(cpu_online_mask); |
fa218f1c PM |
298 | if (cpu == smp_processor_id()) |
299 | cpu = cpumask_next(cpu, cpu_online_mask); | |
300 | if (WARN_ON_ONCE(cpu >= nr_cpu_ids)) | |
301 | return; | |
302 | cpumask_set_cpu(cpu, &cpus_chosen); | |
303 | ||
304 | /* Force a sane value for the boot parameter. */ | |
305 | if (n > nr_cpu_ids) | |
306 | n = nr_cpu_ids; | |
307 | ||
308 | /* | |
309 | * Randomly select the specified number of CPUs. If the same | |
310 | * CPU is selected multiple times, that CPU is checked only once, | |
311 | * and no replacement CPU is selected. This gracefully handles | |
312 | * situations where verify_n_cpus is greater than the number of | |
313 | * CPUs that are currently online. | |
314 | */ | |
315 | for (i = 1; i < n; i++) { | |
8032bf12 | 316 | cpu = get_random_u32_below(nr_cpu_ids); |
fa218f1c PM |
317 | cpu = cpumask_next(cpu - 1, cpu_online_mask); |
318 | if (cpu >= nr_cpu_ids) | |
9b51d9d8 | 319 | cpu = cpumask_first(cpu_online_mask); |
fa218f1c PM |
320 | if (!WARN_ON_ONCE(cpu >= nr_cpu_ids)) |
321 | cpumask_set_cpu(cpu, &cpus_chosen); | |
322 | } | |
323 | ||
324 | /* Don't verify ourselves. */ | |
325 | cpumask_clear_cpu(smp_processor_id(), &cpus_chosen); | |
326 | } | |
7560c02b PM |
327 | |
328 | static void clocksource_verify_one_cpu(void *csin) | |
329 | { | |
330 | struct clocksource *cs = (struct clocksource *)csin; | |
331 | ||
332 | csnow_mid = cs->read(cs); | |
333 | } | |
334 | ||
1253b9b8 | 335 | void clocksource_verify_percpu(struct clocksource *cs) |
7560c02b PM |
336 | { |
337 | int64_t cs_nsec, cs_nsec_max = 0, cs_nsec_min = LLONG_MAX; | |
338 | u64 csnow_begin, csnow_end; | |
339 | int cpu, testcpu; | |
340 | s64 delta; | |
341 | ||
fa218f1c PM |
342 | if (verify_n_cpus == 0) |
343 | return; | |
7560c02b PM |
344 | cpumask_clear(&cpus_ahead); |
345 | cpumask_clear(&cpus_behind); | |
698429f9 | 346 | cpus_read_lock(); |
7560c02b | 347 | preempt_disable(); |
fa218f1c | 348 | clocksource_verify_choose_cpus(); |
8afbcaf8 | 349 | if (cpumask_empty(&cpus_chosen)) { |
fa218f1c | 350 | preempt_enable(); |
698429f9 | 351 | cpus_read_unlock(); |
fa218f1c PM |
352 | pr_warn("Not enough CPUs to check clocksource '%s'.\n", cs->name); |
353 | return; | |
354 | } | |
7560c02b | 355 | testcpu = smp_processor_id(); |
fa218f1c PM |
356 | pr_warn("Checking clocksource %s synchronization from CPU %d to CPUs %*pbl.\n", cs->name, testcpu, cpumask_pr_args(&cpus_chosen)); |
357 | for_each_cpu(cpu, &cpus_chosen) { | |
7560c02b PM |
358 | if (cpu == testcpu) |
359 | continue; | |
360 | csnow_begin = cs->read(cs); | |
361 | smp_call_function_single(cpu, clocksource_verify_one_cpu, cs, 1); | |
362 | csnow_end = cs->read(cs); | |
363 | delta = (s64)((csnow_mid - csnow_begin) & cs->mask); | |
364 | if (delta < 0) | |
365 | cpumask_set_cpu(cpu, &cpus_behind); | |
366 | delta = (csnow_end - csnow_mid) & cs->mask; | |
367 | if (delta < 0) | |
368 | cpumask_set_cpu(cpu, &cpus_ahead); | |
369 | delta = clocksource_delta(csnow_end, csnow_begin, cs->mask); | |
370 | cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift); | |
371 | if (cs_nsec > cs_nsec_max) | |
372 | cs_nsec_max = cs_nsec; | |
373 | if (cs_nsec < cs_nsec_min) | |
374 | cs_nsec_min = cs_nsec; | |
375 | } | |
376 | preempt_enable(); | |
698429f9 | 377 | cpus_read_unlock(); |
7560c02b PM |
378 | if (!cpumask_empty(&cpus_ahead)) |
379 | pr_warn(" CPUs %*pbl ahead of CPU %d for clocksource %s.\n", | |
380 | cpumask_pr_args(&cpus_ahead), testcpu, cs->name); | |
381 | if (!cpumask_empty(&cpus_behind)) | |
382 | pr_warn(" CPUs %*pbl behind CPU %d for clocksource %s.\n", | |
383 | cpumask_pr_args(&cpus_behind), testcpu, cs->name); | |
384 | if (!cpumask_empty(&cpus_ahead) || !cpumask_empty(&cpus_behind)) | |
385 | pr_warn(" CPU %d check durations %lldns - %lldns for clocksource %s.\n", | |
386 | testcpu, cs_nsec_min, cs_nsec_max, cs->name); | |
387 | } | |
1253b9b8 | 388 | EXPORT_SYMBOL_GPL(clocksource_verify_percpu); |
7560c02b | 389 | |
b7082cdf FT |
390 | static inline void clocksource_reset_watchdog(void) |
391 | { | |
392 | struct clocksource *cs; | |
393 | ||
394 | list_for_each_entry(cs, &watchdog_list, wd_list) | |
395 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
396 | } | |
397 | ||
398 | ||
e99e88a9 | 399 | static void clocksource_watchdog(struct timer_list *unused) |
5d8b34fd | 400 | { |
a5a1d1c2 | 401 | u64 csnow, wdnow, cslast, wdlast, delta; |
9fb60336 | 402 | int next_cpu, reset_pending; |
db3a34e1 PM |
403 | int64_t wd_nsec, cs_nsec; |
404 | struct clocksource *cs; | |
c86ff8c5 | 405 | enum wd_read_status read_ret; |
b7082cdf | 406 | unsigned long extra_wait = 0; |
2e27e793 | 407 | u32 md; |
5d8b34fd TG |
408 | |
409 | spin_lock(&watchdog_lock); | |
fb63a0eb MS |
410 | if (!watchdog_running) |
411 | goto out; | |
5d8b34fd | 412 | |
9fb60336 TG |
413 | reset_pending = atomic_read(&watchdog_reset_pending); |
414 | ||
c55c87c8 MS |
415 | list_for_each_entry(cs, &watchdog_list, wd_list) { |
416 | ||
417 | /* Clocksource already marked unstable? */ | |
01548f4d | 418 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
54a6bc0b TG |
419 | if (finished_booting) |
420 | schedule_work(&watchdog_work); | |
c55c87c8 | 421 | continue; |
01548f4d | 422 | } |
c55c87c8 | 423 | |
c86ff8c5 WL |
424 | read_ret = cs_watchdog_read(cs, &csnow, &wdnow); |
425 | ||
b7082cdf FT |
426 | if (read_ret == WD_READ_UNSTABLE) { |
427 | /* Clock readout unreliable, so give it up. */ | |
428 | __clocksource_unstable(cs); | |
db3a34e1 PM |
429 | continue; |
430 | } | |
b52f52a0 | 431 | |
b7082cdf FT |
432 | /* |
433 | * When WD_READ_SKIP is returned, it means the system is likely | |
434 | * under very heavy load, where the latency of reading | |
435 | * watchdog/clocksource is very big, and affect the accuracy of | |
436 | * watchdog check. So give system some space and suspend the | |
437 | * watchdog check for 5 minutes. | |
438 | */ | |
439 | if (read_ret == WD_READ_SKIP) { | |
440 | /* | |
441 | * As the watchdog timer will be suspended, and | |
442 | * cs->last could keep unchanged for 5 minutes, reset | |
443 | * the counters. | |
444 | */ | |
445 | clocksource_reset_watchdog(); | |
446 | extra_wait = HZ * 300; | |
447 | break; | |
448 | } | |
449 | ||
8cf4e750 | 450 | /* Clocksource initialized ? */ |
9fb60336 TG |
451 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) || |
452 | atomic_read(&watchdog_reset_pending)) { | |
8cf4e750 | 453 | cs->flags |= CLOCK_SOURCE_WATCHDOG; |
b5199515 TG |
454 | cs->wd_last = wdnow; |
455 | cs->cs_last = csnow; | |
b52f52a0 TG |
456 | continue; |
457 | } | |
458 | ||
3a978377 TG |
459 | delta = clocksource_delta(wdnow, cs->wd_last, watchdog->mask); |
460 | wd_nsec = clocksource_cyc2ns(delta, watchdog->mult, | |
461 | watchdog->shift); | |
b5199515 | 462 | |
3a978377 TG |
463 | delta = clocksource_delta(csnow, cs->cs_last, cs->mask); |
464 | cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift); | |
0b046b21 JS |
465 | wdlast = cs->wd_last; /* save these in case we print them */ |
466 | cslast = cs->cs_last; | |
b5199515 TG |
467 | cs->cs_last = csnow; |
468 | cs->wd_last = wdnow; | |
469 | ||
9fb60336 TG |
470 | if (atomic_read(&watchdog_reset_pending)) |
471 | continue; | |
472 | ||
b5199515 | 473 | /* Check the deviation from the watchdog clocksource. */ |
2e27e793 PM |
474 | md = cs->uncertainty_margin + watchdog->uncertainty_margin; |
475 | if (abs(cs_nsec - wd_nsec) > md) { | |
dd029269 PM |
476 | u64 cs_wd_msec; |
477 | u64 wd_msec; | |
478 | u32 wd_rem; | |
479 | ||
390dd67c SI |
480 | pr_warn("timekeeping watchdog on CPU%d: Marking clocksource '%s' as unstable because the skew is too large:\n", |
481 | smp_processor_id(), cs->name); | |
22a22383 FT |
482 | pr_warn(" '%s' wd_nsec: %lld wd_now: %llx wd_last: %llx mask: %llx\n", |
483 | watchdog->name, wd_nsec, wdnow, wdlast, watchdog->mask); | |
484 | pr_warn(" '%s' cs_nsec: %lld cs_now: %llx cs_last: %llx mask: %llx\n", | |
485 | cs->name, cs_nsec, csnow, cslast, cs->mask); | |
dd029269 PM |
486 | cs_wd_msec = div_u64_rem(cs_nsec - wd_nsec, 1000U * 1000U, &wd_rem); |
487 | wd_msec = div_u64_rem(wd_nsec, 1000U * 1000U, &wd_rem); | |
488 | pr_warn(" Clocksource '%s' skewed %lld ns (%lld ms) over watchdog '%s' interval of %lld ns (%lld ms)\n", | |
489 | cs->name, cs_nsec - wd_nsec, cs_wd_msec, watchdog->name, wd_nsec, wd_msec); | |
fa218f1c PM |
490 | if (curr_clocksource == cs) |
491 | pr_warn(" '%s' is current clocksource.\n", cs->name); | |
492 | else if (curr_clocksource) | |
493 | pr_warn(" '%s' (not '%s') is current clocksource.\n", curr_clocksource->name, cs->name); | |
494 | else | |
495 | pr_warn(" No current clocksource.\n"); | |
0b046b21 | 496 | __clocksource_unstable(cs); |
8cf4e750 MS |
497 | continue; |
498 | } | |
499 | ||
b421b22b PZ |
500 | if (cs == curr_clocksource && cs->tick_stable) |
501 | cs->tick_stable(cs); | |
502 | ||
8cf4e750 MS |
503 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && |
504 | (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
505 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
332962f2 | 506 | /* Mark it valid for high-res. */ |
8cf4e750 | 507 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
332962f2 TG |
508 | |
509 | /* | |
510 | * clocksource_done_booting() will sort it if | |
511 | * finished_booting is not set yet. | |
512 | */ | |
513 | if (!finished_booting) | |
514 | continue; | |
515 | ||
8cf4e750 | 516 | /* |
332962f2 TG |
517 | * If this is not the current clocksource let |
518 | * the watchdog thread reselect it. Due to the | |
519 | * change to high res this clocksource might | |
520 | * be preferred now. If it is the current | |
521 | * clocksource let the tick code know about | |
522 | * that change. | |
8cf4e750 | 523 | */ |
332962f2 TG |
524 | if (cs != curr_clocksource) { |
525 | cs->flags |= CLOCK_SOURCE_RESELECT; | |
526 | schedule_work(&watchdog_work); | |
527 | } else { | |
528 | tick_clock_notify(); | |
529 | } | |
5d8b34fd TG |
530 | } |
531 | } | |
532 | ||
9fb60336 TG |
533 | /* |
534 | * We only clear the watchdog_reset_pending, when we did a | |
535 | * full cycle through all clocksources. | |
536 | */ | |
537 | if (reset_pending) | |
538 | atomic_dec(&watchdog_reset_pending); | |
539 | ||
c55c87c8 MS |
540 | /* |
541 | * Cycle through CPUs to check if the CPUs stay synchronized | |
542 | * to each other. | |
543 | */ | |
544 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); | |
545 | if (next_cpu >= nr_cpu_ids) | |
546 | next_cpu = cpumask_first(cpu_online_mask); | |
febac332 KK |
547 | |
548 | /* | |
549 | * Arm timer if not already pending: could race with concurrent | |
550 | * pair clocksource_stop_watchdog() clocksource_start_watchdog(). | |
551 | */ | |
552 | if (!timer_pending(&watchdog_timer)) { | |
b7082cdf | 553 | watchdog_timer.expires += WATCHDOG_INTERVAL + extra_wait; |
febac332 KK |
554 | add_timer_on(&watchdog_timer, next_cpu); |
555 | } | |
fb63a0eb | 556 | out: |
5d8b34fd TG |
557 | spin_unlock(&watchdog_lock); |
558 | } | |
0f8e8ef7 | 559 | |
fb63a0eb MS |
560 | static inline void clocksource_start_watchdog(void) |
561 | { | |
562 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) | |
563 | return; | |
e99e88a9 | 564 | timer_setup(&watchdog_timer, clocksource_watchdog, 0); |
fb63a0eb MS |
565 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; |
566 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); | |
567 | watchdog_running = 1; | |
568 | } | |
569 | ||
570 | static inline void clocksource_stop_watchdog(void) | |
571 | { | |
572 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) | |
573 | return; | |
574 | del_timer(&watchdog_timer); | |
575 | watchdog_running = 0; | |
576 | } | |
577 | ||
b52f52a0 TG |
578 | static void clocksource_resume_watchdog(void) |
579 | { | |
9fb60336 | 580 | atomic_inc(&watchdog_reset_pending); |
b52f52a0 TG |
581 | } |
582 | ||
fb63a0eb | 583 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
5d8b34fd | 584 | { |
5b9e886a PZ |
585 | INIT_LIST_HEAD(&cs->wd_list); |
586 | ||
5d8b34fd | 587 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { |
fb63a0eb | 588 | /* cs is a clocksource to be watched. */ |
5d8b34fd | 589 | list_add(&cs->wd_list, &watchdog_list); |
fb63a0eb | 590 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
948ac6d7 | 591 | } else { |
fb63a0eb | 592 | /* cs is a watchdog. */ |
948ac6d7 | 593 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
5d8b34fd | 594 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
bbf66d89 | 595 | } |
bbf66d89 VK |
596 | } |
597 | ||
598 | static void clocksource_select_watchdog(bool fallback) | |
599 | { | |
600 | struct clocksource *cs, *old_wd; | |
601 | unsigned long flags; | |
602 | ||
603 | spin_lock_irqsave(&watchdog_lock, flags); | |
604 | /* save current watchdog */ | |
605 | old_wd = watchdog; | |
606 | if (fallback) | |
607 | watchdog = NULL; | |
608 | ||
609 | list_for_each_entry(cs, &clocksource_list, list) { | |
610 | /* cs is a clocksource to be watched. */ | |
611 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) | |
612 | continue; | |
613 | ||
614 | /* Skip current if we were requested for a fallback. */ | |
615 | if (fallback && cs == old_wd) | |
616 | continue; | |
617 | ||
fb63a0eb | 618 | /* Pick the best watchdog. */ |
bbf66d89 | 619 | if (!watchdog || cs->rating > watchdog->rating) |
5d8b34fd | 620 | watchdog = cs; |
5d8b34fd | 621 | } |
bbf66d89 VK |
622 | /* If we failed to find a fallback restore the old one. */ |
623 | if (!watchdog) | |
624 | watchdog = old_wd; | |
625 | ||
626 | /* If we changed the watchdog we need to reset cycles. */ | |
627 | if (watchdog != old_wd) | |
628 | clocksource_reset_watchdog(); | |
629 | ||
fb63a0eb MS |
630 | /* Check if the watchdog timer needs to be started. */ |
631 | clocksource_start_watchdog(); | |
5d8b34fd TG |
632 | spin_unlock_irqrestore(&watchdog_lock, flags); |
633 | } | |
fb63a0eb MS |
634 | |
635 | static void clocksource_dequeue_watchdog(struct clocksource *cs) | |
636 | { | |
a89c7edb TG |
637 | if (cs != watchdog) { |
638 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
639 | /* cs is a watched clocksource. */ | |
640 | list_del_init(&cs->wd_list); | |
641 | /* Check if the watchdog timer needs to be stopped. */ | |
642 | clocksource_stop_watchdog(); | |
fb63a0eb MS |
643 | } |
644 | } | |
fb63a0eb MS |
645 | } |
646 | ||
e2c631ba | 647 | static int __clocksource_watchdog_kthread(void) |
c55c87c8 MS |
648 | { |
649 | struct clocksource *cs, *tmp; | |
650 | unsigned long flags; | |
332962f2 | 651 | int select = 0; |
c55c87c8 | 652 | |
7560c02b PM |
653 | /* Do any required per-CPU skew verification. */ |
654 | if (curr_clocksource && | |
655 | curr_clocksource->flags & CLOCK_SOURCE_UNSTABLE && | |
656 | curr_clocksource->flags & CLOCK_SOURCE_VERIFY_PERCPU) | |
657 | clocksource_verify_percpu(curr_clocksource); | |
658 | ||
c55c87c8 | 659 | spin_lock_irqsave(&watchdog_lock, flags); |
332962f2 | 660 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { |
c55c87c8 MS |
661 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
662 | list_del_init(&cs->wd_list); | |
2aae7bcf | 663 | __clocksource_change_rating(cs, 0); |
332962f2 TG |
664 | select = 1; |
665 | } | |
666 | if (cs->flags & CLOCK_SOURCE_RESELECT) { | |
667 | cs->flags &= ~CLOCK_SOURCE_RESELECT; | |
668 | select = 1; | |
c55c87c8 | 669 | } |
332962f2 | 670 | } |
c55c87c8 MS |
671 | /* Check if the watchdog timer needs to be stopped. */ |
672 | clocksource_stop_watchdog(); | |
6ea41d25 TG |
673 | spin_unlock_irqrestore(&watchdog_lock, flags); |
674 | ||
332962f2 TG |
675 | return select; |
676 | } | |
677 | ||
e2c631ba | 678 | static int clocksource_watchdog_kthread(void *data) |
332962f2 TG |
679 | { |
680 | mutex_lock(&clocksource_mutex); | |
e2c631ba | 681 | if (__clocksource_watchdog_kthread()) |
332962f2 | 682 | clocksource_select(); |
d0981a1b | 683 | mutex_unlock(&clocksource_mutex); |
e2c631ba | 684 | return 0; |
c55c87c8 MS |
685 | } |
686 | ||
7eaeb343 TG |
687 | static bool clocksource_is_watchdog(struct clocksource *cs) |
688 | { | |
689 | return cs == watchdog; | |
690 | } | |
691 | ||
fb63a0eb MS |
692 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
693 | ||
694 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
5d8b34fd TG |
695 | { |
696 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
697 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
698 | } | |
b52f52a0 | 699 | |
bbf66d89 | 700 | static void clocksource_select_watchdog(bool fallback) { } |
fb63a0eb | 701 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
b52f52a0 | 702 | static inline void clocksource_resume_watchdog(void) { } |
e2c631ba | 703 | static inline int __clocksource_watchdog_kthread(void) { return 0; } |
7eaeb343 | 704 | static bool clocksource_is_watchdog(struct clocksource *cs) { return false; } |
397bbf6d | 705 | void clocksource_mark_unstable(struct clocksource *cs) { } |
fb63a0eb | 706 | |
db6f9e55 MM |
707 | static inline void clocksource_watchdog_lock(unsigned long *flags) { } |
708 | static inline void clocksource_watchdog_unlock(unsigned long *flags) { } | |
2aae7bcf | 709 | |
fb63a0eb | 710 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
5d8b34fd | 711 | |
39232ed5 BW |
712 | static bool clocksource_is_suspend(struct clocksource *cs) |
713 | { | |
714 | return cs == suspend_clocksource; | |
715 | } | |
716 | ||
717 | static void __clocksource_suspend_select(struct clocksource *cs) | |
718 | { | |
719 | /* | |
720 | * Skip the clocksource which will be stopped in suspend state. | |
721 | */ | |
722 | if (!(cs->flags & CLOCK_SOURCE_SUSPEND_NONSTOP)) | |
723 | return; | |
724 | ||
725 | /* | |
726 | * The nonstop clocksource can be selected as the suspend clocksource to | |
727 | * calculate the suspend time, so it should not supply suspend/resume | |
728 | * interfaces to suspend the nonstop clocksource when system suspends. | |
729 | */ | |
730 | if (cs->suspend || cs->resume) { | |
731 | pr_warn("Nonstop clocksource %s should not supply suspend/resume interfaces\n", | |
732 | cs->name); | |
733 | } | |
734 | ||
735 | /* Pick the best rating. */ | |
736 | if (!suspend_clocksource || cs->rating > suspend_clocksource->rating) | |
737 | suspend_clocksource = cs; | |
738 | } | |
739 | ||
740 | /** | |
741 | * clocksource_suspend_select - Select the best clocksource for suspend timing | |
742 | * @fallback: if select a fallback clocksource | |
743 | */ | |
744 | static void clocksource_suspend_select(bool fallback) | |
745 | { | |
746 | struct clocksource *cs, *old_suspend; | |
747 | ||
748 | old_suspend = suspend_clocksource; | |
749 | if (fallback) | |
750 | suspend_clocksource = NULL; | |
751 | ||
752 | list_for_each_entry(cs, &clocksource_list, list) { | |
753 | /* Skip current if we were requested for a fallback. */ | |
754 | if (fallback && cs == old_suspend) | |
755 | continue; | |
756 | ||
757 | __clocksource_suspend_select(cs); | |
758 | } | |
759 | } | |
760 | ||
761 | /** | |
762 | * clocksource_start_suspend_timing - Start measuring the suspend timing | |
763 | * @cs: current clocksource from timekeeping | |
764 | * @start_cycles: current cycles from timekeeping | |
765 | * | |
766 | * This function will save the start cycle values of suspend timer to calculate | |
767 | * the suspend time when resuming system. | |
768 | * | |
769 | * This function is called late in the suspend process from timekeeping_suspend(), | |
4bf07f65 | 770 | * that means processes are frozen, non-boot cpus and interrupts are disabled |
39232ed5 BW |
771 | * now. It is therefore possible to start the suspend timer without taking the |
772 | * clocksource mutex. | |
773 | */ | |
774 | void clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles) | |
775 | { | |
776 | if (!suspend_clocksource) | |
777 | return; | |
778 | ||
779 | /* | |
780 | * If current clocksource is the suspend timer, we should use the | |
781 | * tkr_mono.cycle_last value as suspend_start to avoid same reading | |
782 | * from suspend timer. | |
783 | */ | |
784 | if (clocksource_is_suspend(cs)) { | |
785 | suspend_start = start_cycles; | |
786 | return; | |
787 | } | |
788 | ||
789 | if (suspend_clocksource->enable && | |
790 | suspend_clocksource->enable(suspend_clocksource)) { | |
791 | pr_warn_once("Failed to enable the non-suspend-able clocksource.\n"); | |
792 | return; | |
793 | } | |
794 | ||
795 | suspend_start = suspend_clocksource->read(suspend_clocksource); | |
796 | } | |
797 | ||
798 | /** | |
799 | * clocksource_stop_suspend_timing - Stop measuring the suspend timing | |
800 | * @cs: current clocksource from timekeeping | |
801 | * @cycle_now: current cycles from timekeeping | |
802 | * | |
803 | * This function will calculate the suspend time from suspend timer. | |
804 | * | |
805 | * Returns nanoseconds since suspend started, 0 if no usable suspend clocksource. | |
806 | * | |
807 | * This function is called early in the resume process from timekeeping_resume(), | |
808 | * that means there is only one cpu, no processes are running and the interrupts | |
809 | * are disabled. It is therefore possible to stop the suspend timer without | |
810 | * taking the clocksource mutex. | |
811 | */ | |
812 | u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 cycle_now) | |
813 | { | |
814 | u64 now, delta, nsec = 0; | |
815 | ||
816 | if (!suspend_clocksource) | |
817 | return 0; | |
818 | ||
819 | /* | |
820 | * If current clocksource is the suspend timer, we should use the | |
821 | * tkr_mono.cycle_last value from timekeeping as current cycle to | |
822 | * avoid same reading from suspend timer. | |
823 | */ | |
824 | if (clocksource_is_suspend(cs)) | |
825 | now = cycle_now; | |
826 | else | |
827 | now = suspend_clocksource->read(suspend_clocksource); | |
828 | ||
829 | if (now > suspend_start) { | |
830 | delta = clocksource_delta(now, suspend_start, | |
831 | suspend_clocksource->mask); | |
832 | nsec = mul_u64_u32_shr(delta, suspend_clocksource->mult, | |
833 | suspend_clocksource->shift); | |
834 | } | |
835 | ||
836 | /* | |
837 | * Disable the suspend timer to save power if current clocksource is | |
838 | * not the suspend timer. | |
839 | */ | |
840 | if (!clocksource_is_suspend(cs) && suspend_clocksource->disable) | |
841 | suspend_clocksource->disable(suspend_clocksource); | |
842 | ||
843 | return nsec; | |
844 | } | |
845 | ||
c54a42b1 MD |
846 | /** |
847 | * clocksource_suspend - suspend the clocksource(s) | |
848 | */ | |
849 | void clocksource_suspend(void) | |
850 | { | |
851 | struct clocksource *cs; | |
852 | ||
853 | list_for_each_entry_reverse(cs, &clocksource_list, list) | |
854 | if (cs->suspend) | |
855 | cs->suspend(cs); | |
856 | } | |
857 | ||
b52f52a0 TG |
858 | /** |
859 | * clocksource_resume - resume the clocksource(s) | |
860 | */ | |
861 | void clocksource_resume(void) | |
862 | { | |
2e197586 | 863 | struct clocksource *cs; |
b52f52a0 | 864 | |
75c5158f | 865 | list_for_each_entry(cs, &clocksource_list, list) |
b52f52a0 | 866 | if (cs->resume) |
17622339 | 867 | cs->resume(cs); |
b52f52a0 TG |
868 | |
869 | clocksource_resume_watchdog(); | |
b52f52a0 TG |
870 | } |
871 | ||
7c3078b6 JW |
872 | /** |
873 | * clocksource_touch_watchdog - Update watchdog | |
874 | * | |
875 | * Update the watchdog after exception contexts such as kgdb so as not | |
7b7422a5 TG |
876 | * to incorrectly trip the watchdog. This might fail when the kernel |
877 | * was stopped in code which holds watchdog_lock. | |
7c3078b6 JW |
878 | */ |
879 | void clocksource_touch_watchdog(void) | |
880 | { | |
881 | clocksource_resume_watchdog(); | |
882 | } | |
883 | ||
d65670a7 JS |
884 | /** |
885 | * clocksource_max_adjustment- Returns max adjustment amount | |
886 | * @cs: Pointer to clocksource | |
887 | * | |
888 | */ | |
889 | static u32 clocksource_max_adjustment(struct clocksource *cs) | |
890 | { | |
891 | u64 ret; | |
892 | /* | |
88b28adf | 893 | * We won't try to correct for more than 11% adjustments (110,000 ppm), |
d65670a7 JS |
894 | */ |
895 | ret = (u64)cs->mult * 11; | |
896 | do_div(ret,100); | |
897 | return (u32)ret; | |
898 | } | |
899 | ||
98962465 | 900 | /** |
87d8b9eb SB |
901 | * clocks_calc_max_nsecs - Returns maximum nanoseconds that can be converted |
902 | * @mult: cycle to nanosecond multiplier | |
903 | * @shift: cycle to nanosecond divisor (power of two) | |
904 | * @maxadj: maximum adjustment value to mult (~11%) | |
905 | * @mask: bitmask for two's complement subtraction of non 64 bit counters | |
fb82fe2f JS |
906 | * @max_cyc: maximum cycle value before potential overflow (does not include |
907 | * any safety margin) | |
362fde04 | 908 | * |
8e56f33f JS |
909 | * NOTE: This function includes a safety margin of 50%, in other words, we |
910 | * return half the number of nanoseconds the hardware counter can technically | |
911 | * cover. This is done so that we can potentially detect problems caused by | |
912 | * delayed timers or bad hardware, which might result in time intervals that | |
571af55a | 913 | * are larger than what the math used can handle without overflows. |
98962465 | 914 | */ |
fb82fe2f | 915 | u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cyc) |
98962465 JH |
916 | { |
917 | u64 max_nsecs, max_cycles; | |
918 | ||
919 | /* | |
920 | * Calculate the maximum number of cycles that we can pass to the | |
6086e346 | 921 | * cyc2ns() function without overflowing a 64-bit result. |
98962465 | 922 | */ |
6086e346 JS |
923 | max_cycles = ULLONG_MAX; |
924 | do_div(max_cycles, mult+maxadj); | |
98962465 JH |
925 | |
926 | /* | |
927 | * The actual maximum number of cycles we can defer the clocksource is | |
87d8b9eb | 928 | * determined by the minimum of max_cycles and mask. |
d65670a7 JS |
929 | * Note: Here we subtract the maxadj to make sure we don't sleep for |
930 | * too long if there's a large negative adjustment. | |
98962465 | 931 | */ |
87d8b9eb SB |
932 | max_cycles = min(max_cycles, mask); |
933 | max_nsecs = clocksource_cyc2ns(max_cycles, mult - maxadj, shift); | |
934 | ||
fb82fe2f JS |
935 | /* return the max_cycles value as well if requested */ |
936 | if (max_cyc) | |
937 | *max_cyc = max_cycles; | |
938 | ||
362fde04 JS |
939 | /* Return 50% of the actual maximum, so we can detect bad values */ |
940 | max_nsecs >>= 1; | |
941 | ||
87d8b9eb SB |
942 | return max_nsecs; |
943 | } | |
944 | ||
945 | /** | |
fb82fe2f JS |
946 | * clocksource_update_max_deferment - Updates the clocksource max_idle_ns & max_cycles |
947 | * @cs: Pointer to clocksource to be updated | |
87d8b9eb SB |
948 | * |
949 | */ | |
fb82fe2f | 950 | static inline void clocksource_update_max_deferment(struct clocksource *cs) |
87d8b9eb | 951 | { |
fb82fe2f JS |
952 | cs->max_idle_ns = clocks_calc_max_nsecs(cs->mult, cs->shift, |
953 | cs->maxadj, cs->mask, | |
954 | &cs->max_cycles); | |
98962465 JH |
955 | } |
956 | ||
f5a2e343 | 957 | static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur) |
5d33b883 TG |
958 | { |
959 | struct clocksource *cs; | |
960 | ||
961 | if (!finished_booting || list_empty(&clocksource_list)) | |
962 | return NULL; | |
963 | ||
964 | /* | |
965 | * We pick the clocksource with the highest rating. If oneshot | |
966 | * mode is active, we pick the highres valid clocksource with | |
967 | * the best rating. | |
968 | */ | |
969 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
970 | if (skipcur && cs == curr_clocksource) |
971 | continue; | |
5d33b883 TG |
972 | if (oneshot && !(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES)) |
973 | continue; | |
974 | return cs; | |
975 | } | |
976 | return NULL; | |
977 | } | |
978 | ||
f5a2e343 | 979 | static void __clocksource_select(bool skipcur) |
734efb46 | 980 | { |
5d33b883 | 981 | bool oneshot = tick_oneshot_mode_active(); |
f1b82746 | 982 | struct clocksource *best, *cs; |
5d8b34fd | 983 | |
5d33b883 | 984 | /* Find the best suitable clocksource */ |
f5a2e343 | 985 | best = clocksource_find_best(oneshot, skipcur); |
5d33b883 | 986 | if (!best) |
f1b82746 | 987 | return; |
5d33b883 | 988 | |
7f852afe BW |
989 | if (!strlen(override_name)) |
990 | goto found; | |
991 | ||
f1b82746 MS |
992 | /* Check for the override clocksource. */ |
993 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
994 | if (skipcur && cs == curr_clocksource) |
995 | continue; | |
f1b82746 MS |
996 | if (strcmp(cs->name, override_name) != 0) |
997 | continue; | |
998 | /* | |
999 | * Check to make sure we don't switch to a non-highres | |
1000 | * capable clocksource if the tick code is in oneshot | |
1001 | * mode (highres or nohz) | |
1002 | */ | |
5d33b883 | 1003 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && oneshot) { |
f1b82746 | 1004 | /* Override clocksource cannot be used. */ |
36374583 KW |
1005 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
1006 | pr_warn("Override clocksource %s is unstable and not HRT compatible - cannot switch while in HRT/NOHZ mode\n", | |
1007 | cs->name); | |
1008 | override_name[0] = 0; | |
1009 | } else { | |
1010 | /* | |
1011 | * The override cannot be currently verified. | |
1012 | * Deferring to let the watchdog check. | |
1013 | */ | |
1014 | pr_info("Override clocksource %s is not currently HRT compatible - deferring\n", | |
1015 | cs->name); | |
1016 | } | |
f1b82746 MS |
1017 | } else |
1018 | /* Override clocksource can be used. */ | |
1019 | best = cs; | |
1020 | break; | |
1021 | } | |
ba919d1c | 1022 | |
7f852afe | 1023 | found: |
ba919d1c TG |
1024 | if (curr_clocksource != best && !timekeeping_notify(best)) { |
1025 | pr_info("Switched to clocksource %s\n", best->name); | |
75c5158f | 1026 | curr_clocksource = best; |
75c5158f | 1027 | } |
f1b82746 | 1028 | } |
734efb46 | 1029 | |
f5a2e343 TG |
1030 | /** |
1031 | * clocksource_select - Select the best clocksource available | |
1032 | * | |
1033 | * Private function. Must hold clocksource_mutex when called. | |
1034 | * | |
1035 | * Select the clocksource with the best rating, or the clocksource, | |
1036 | * which is selected by userspace override. | |
1037 | */ | |
1038 | static void clocksource_select(void) | |
1039 | { | |
cfed432d | 1040 | __clocksource_select(false); |
f5a2e343 TG |
1041 | } |
1042 | ||
7eaeb343 TG |
1043 | static void clocksource_select_fallback(void) |
1044 | { | |
cfed432d | 1045 | __clocksource_select(true); |
7eaeb343 TG |
1046 | } |
1047 | ||
75c5158f MS |
1048 | /* |
1049 | * clocksource_done_booting - Called near the end of core bootup | |
1050 | * | |
1051 | * Hack to avoid lots of clocksource churn at boot time. | |
1052 | * We use fs_initcall because we want this to start before | |
1053 | * device_initcall but after subsys_initcall. | |
1054 | */ | |
1055 | static int __init clocksource_done_booting(void) | |
1056 | { | |
ad6759fb | 1057 | mutex_lock(&clocksource_mutex); |
1058 | curr_clocksource = clocksource_default_clock(); | |
75c5158f | 1059 | finished_booting = 1; |
54a6bc0b TG |
1060 | /* |
1061 | * Run the watchdog first to eliminate unstable clock sources | |
1062 | */ | |
e2c631ba | 1063 | __clocksource_watchdog_kthread(); |
75c5158f | 1064 | clocksource_select(); |
e6c73305 | 1065 | mutex_unlock(&clocksource_mutex); |
75c5158f MS |
1066 | return 0; |
1067 | } | |
1068 | fs_initcall(clocksource_done_booting); | |
1069 | ||
92c7e002 TG |
1070 | /* |
1071 | * Enqueue the clocksource sorted by rating | |
734efb46 | 1072 | */ |
f1b82746 | 1073 | static void clocksource_enqueue(struct clocksource *cs) |
734efb46 | 1074 | { |
f1b82746 MS |
1075 | struct list_head *entry = &clocksource_list; |
1076 | struct clocksource *tmp; | |
92c7e002 | 1077 | |
0fb71d34 | 1078 | list_for_each_entry(tmp, &clocksource_list, list) { |
92c7e002 | 1079 | /* Keep track of the place, where to insert */ |
0fb71d34 MH |
1080 | if (tmp->rating < cs->rating) |
1081 | break; | |
1082 | entry = &tmp->list; | |
1083 | } | |
f1b82746 | 1084 | list_add(&cs->list, entry); |
734efb46 | 1085 | } |
1086 | ||
d7e81c26 | 1087 | /** |
fba9e072 | 1088 | * __clocksource_update_freq_scale - Used update clocksource with new freq |
b1b73d09 | 1089 | * @cs: clocksource to be registered |
d7e81c26 JS |
1090 | * @scale: Scale factor multiplied against freq to get clocksource hz |
1091 | * @freq: clocksource frequency (cycles per second) divided by scale | |
1092 | * | |
852db46d | 1093 | * This should only be called from the clocksource->enable() method. |
d7e81c26 JS |
1094 | * |
1095 | * This *SHOULD NOT* be called directly! Please use the | |
fba9e072 JS |
1096 | * __clocksource_update_freq_hz() or __clocksource_update_freq_khz() helper |
1097 | * functions. | |
d7e81c26 | 1098 | */ |
fba9e072 | 1099 | void __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq) |
d7e81c26 | 1100 | { |
c0e299b1 | 1101 | u64 sec; |
f8935983 | 1102 | |
d7e81c26 | 1103 | /* |
f8935983 JS |
1104 | * Default clocksources are *special* and self-define their mult/shift. |
1105 | * But, you're not special, so you should specify a freq value. | |
d7e81c26 | 1106 | */ |
f8935983 JS |
1107 | if (freq) { |
1108 | /* | |
1109 | * Calc the maximum number of seconds which we can run before | |
1110 | * wrapping around. For clocksources which have a mask > 32-bit | |
1111 | * we need to limit the max sleep time to have a good | |
1112 | * conversion precision. 10 minutes is still a reasonable | |
1113 | * amount. That results in a shift value of 24 for a | |
1114 | * clocksource with mask >= 40-bit and f >= 4GHz. That maps to | |
1115 | * ~ 0.06ppm granularity for NTP. | |
1116 | */ | |
1117 | sec = cs->mask; | |
1118 | do_div(sec, freq); | |
1119 | do_div(sec, scale); | |
1120 | if (!sec) | |
1121 | sec = 1; | |
1122 | else if (sec > 600 && cs->mask > UINT_MAX) | |
1123 | sec = 600; | |
1124 | ||
1125 | clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, | |
1126 | NSEC_PER_SEC / scale, sec * scale); | |
1127 | } | |
2e27e793 PM |
1128 | |
1129 | /* | |
1130 | * If the uncertainty margin is not specified, calculate it. | |
1131 | * If both scale and freq are non-zero, calculate the clock | |
1132 | * period, but bound below at 2*WATCHDOG_MAX_SKEW. However, | |
1133 | * if either of scale or freq is zero, be very conservative and | |
1134 | * take the tens-of-milliseconds WATCHDOG_THRESHOLD value for the | |
1135 | * uncertainty margin. Allow stupidly small uncertainty margins | |
1136 | * to be specified by the caller for testing purposes, but warn | |
1137 | * to discourage production use of this capability. | |
1138 | */ | |
1139 | if (scale && freq && !cs->uncertainty_margin) { | |
1140 | cs->uncertainty_margin = NSEC_PER_SEC / (scale * freq); | |
1141 | if (cs->uncertainty_margin < 2 * WATCHDOG_MAX_SKEW) | |
1142 | cs->uncertainty_margin = 2 * WATCHDOG_MAX_SKEW; | |
1143 | } else if (!cs->uncertainty_margin) { | |
1144 | cs->uncertainty_margin = WATCHDOG_THRESHOLD; | |
1145 | } | |
1146 | WARN_ON_ONCE(cs->uncertainty_margin < 2 * WATCHDOG_MAX_SKEW); | |
1147 | ||
d65670a7 | 1148 | /* |
362fde04 JS |
1149 | * Ensure clocksources that have large 'mult' values don't overflow |
1150 | * when adjusted. | |
d65670a7 JS |
1151 | */ |
1152 | cs->maxadj = clocksource_max_adjustment(cs); | |
f8935983 JS |
1153 | while (freq && ((cs->mult + cs->maxadj < cs->mult) |
1154 | || (cs->mult - cs->maxadj > cs->mult))) { | |
d65670a7 JS |
1155 | cs->mult >>= 1; |
1156 | cs->shift--; | |
1157 | cs->maxadj = clocksource_max_adjustment(cs); | |
1158 | } | |
1159 | ||
f8935983 JS |
1160 | /* |
1161 | * Only warn for *special* clocksources that self-define | |
1162 | * their mult/shift values and don't specify a freq. | |
1163 | */ | |
1164 | WARN_ONCE(cs->mult + cs->maxadj < cs->mult, | |
1165 | "timekeeping: Clocksource %s might overflow on 11%% adjustment\n", | |
1166 | cs->name); | |
1167 | ||
fb82fe2f | 1168 | clocksource_update_max_deferment(cs); |
8cc8c525 | 1169 | |
45bbfe64 JP |
1170 | pr_info("%s: mask: 0x%llx max_cycles: 0x%llx, max_idle_ns: %lld ns\n", |
1171 | cs->name, cs->mask, cs->max_cycles, cs->max_idle_ns); | |
852db46d | 1172 | } |
fba9e072 | 1173 | EXPORT_SYMBOL_GPL(__clocksource_update_freq_scale); |
852db46d JS |
1174 | |
1175 | /** | |
1176 | * __clocksource_register_scale - Used to install new clocksources | |
b1b73d09 | 1177 | * @cs: clocksource to be registered |
852db46d JS |
1178 | * @scale: Scale factor multiplied against freq to get clocksource hz |
1179 | * @freq: clocksource frequency (cycles per second) divided by scale | |
1180 | * | |
1181 | * Returns -EBUSY if registration fails, zero otherwise. | |
1182 | * | |
1183 | * This *SHOULD NOT* be called directly! Please use the | |
1184 | * clocksource_register_hz() or clocksource_register_khz helper functions. | |
1185 | */ | |
1186 | int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) | |
1187 | { | |
2aae7bcf | 1188 | unsigned long flags; |
852db46d | 1189 | |
d67f34c1 TG |
1190 | clocksource_arch_init(cs); |
1191 | ||
b2c67cbe TG |
1192 | if (WARN_ON_ONCE((unsigned int)cs->id >= CSID_MAX)) |
1193 | cs->id = CSID_GENERIC; | |
5d51bee7 TG |
1194 | if (cs->vdso_clock_mode < 0 || |
1195 | cs->vdso_clock_mode >= VDSO_CLOCKMODE_MAX) { | |
1196 | pr_warn("clocksource %s registered with invalid VDSO mode %d. Disabling VDSO support.\n", | |
1197 | cs->name, cs->vdso_clock_mode); | |
1198 | cs->vdso_clock_mode = VDSO_CLOCKMODE_NONE; | |
1199 | } | |
5d51bee7 | 1200 | |
b595076a | 1201 | /* Initialize mult/shift and max_idle_ns */ |
fba9e072 | 1202 | __clocksource_update_freq_scale(cs, scale, freq); |
d7e81c26 | 1203 | |
be278e98 | 1204 | /* Add clocksource to the clocksource list */ |
d7e81c26 | 1205 | mutex_lock(&clocksource_mutex); |
2aae7bcf PZ |
1206 | |
1207 | clocksource_watchdog_lock(&flags); | |
d7e81c26 | 1208 | clocksource_enqueue(cs); |
d7e81c26 | 1209 | clocksource_enqueue_watchdog(cs); |
2aae7bcf PZ |
1210 | clocksource_watchdog_unlock(&flags); |
1211 | ||
e05b2efb | 1212 | clocksource_select(); |
bbf66d89 | 1213 | clocksource_select_watchdog(false); |
39232ed5 | 1214 | __clocksource_suspend_select(cs); |
d7e81c26 JS |
1215 | mutex_unlock(&clocksource_mutex); |
1216 | return 0; | |
1217 | } | |
1218 | EXPORT_SYMBOL_GPL(__clocksource_register_scale); | |
1219 | ||
d0981a1b TG |
1220 | static void __clocksource_change_rating(struct clocksource *cs, int rating) |
1221 | { | |
1222 | list_del(&cs->list); | |
1223 | cs->rating = rating; | |
1224 | clocksource_enqueue(cs); | |
d0981a1b TG |
1225 | } |
1226 | ||
734efb46 | 1227 | /** |
92c7e002 | 1228 | * clocksource_change_rating - Change the rating of a registered clocksource |
b1b73d09 KK |
1229 | * @cs: clocksource to be changed |
1230 | * @rating: new rating | |
734efb46 | 1231 | */ |
92c7e002 | 1232 | void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb46 | 1233 | { |
2aae7bcf PZ |
1234 | unsigned long flags; |
1235 | ||
75c5158f | 1236 | mutex_lock(&clocksource_mutex); |
2aae7bcf | 1237 | clocksource_watchdog_lock(&flags); |
d0981a1b | 1238 | __clocksource_change_rating(cs, rating); |
2aae7bcf PZ |
1239 | clocksource_watchdog_unlock(&flags); |
1240 | ||
332962f2 | 1241 | clocksource_select(); |
bbf66d89 | 1242 | clocksource_select_watchdog(false); |
39232ed5 | 1243 | clocksource_suspend_select(false); |
75c5158f | 1244 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1245 | } |
fb63a0eb | 1246 | EXPORT_SYMBOL(clocksource_change_rating); |
734efb46 | 1247 | |
7eaeb343 TG |
1248 | /* |
1249 | * Unbind clocksource @cs. Called with clocksource_mutex held | |
1250 | */ | |
1251 | static int clocksource_unbind(struct clocksource *cs) | |
1252 | { | |
2aae7bcf PZ |
1253 | unsigned long flags; |
1254 | ||
bbf66d89 VK |
1255 | if (clocksource_is_watchdog(cs)) { |
1256 | /* Select and try to install a replacement watchdog. */ | |
1257 | clocksource_select_watchdog(true); | |
1258 | if (clocksource_is_watchdog(cs)) | |
1259 | return -EBUSY; | |
1260 | } | |
7eaeb343 TG |
1261 | |
1262 | if (cs == curr_clocksource) { | |
1263 | /* Select and try to install a replacement clock source */ | |
1264 | clocksource_select_fallback(); | |
1265 | if (curr_clocksource == cs) | |
1266 | return -EBUSY; | |
1267 | } | |
2aae7bcf | 1268 | |
39232ed5 BW |
1269 | if (clocksource_is_suspend(cs)) { |
1270 | /* | |
1271 | * Select and try to install a replacement suspend clocksource. | |
1272 | * If no replacement suspend clocksource, we will just let the | |
1273 | * clocksource go and have no suspend clocksource. | |
1274 | */ | |
1275 | clocksource_suspend_select(true); | |
1276 | } | |
1277 | ||
2aae7bcf | 1278 | clocksource_watchdog_lock(&flags); |
7eaeb343 TG |
1279 | clocksource_dequeue_watchdog(cs); |
1280 | list_del_init(&cs->list); | |
2aae7bcf PZ |
1281 | clocksource_watchdog_unlock(&flags); |
1282 | ||
7eaeb343 TG |
1283 | return 0; |
1284 | } | |
1285 | ||
4713e22c TG |
1286 | /** |
1287 | * clocksource_unregister - remove a registered clocksource | |
b1b73d09 | 1288 | * @cs: clocksource to be unregistered |
4713e22c | 1289 | */ |
a89c7edb | 1290 | int clocksource_unregister(struct clocksource *cs) |
4713e22c | 1291 | { |
a89c7edb TG |
1292 | int ret = 0; |
1293 | ||
75c5158f | 1294 | mutex_lock(&clocksource_mutex); |
a89c7edb TG |
1295 | if (!list_empty(&cs->list)) |
1296 | ret = clocksource_unbind(cs); | |
75c5158f | 1297 | mutex_unlock(&clocksource_mutex); |
a89c7edb | 1298 | return ret; |
4713e22c | 1299 | } |
fb63a0eb | 1300 | EXPORT_SYMBOL(clocksource_unregister); |
4713e22c | 1301 | |
2b013700 | 1302 | #ifdef CONFIG_SYSFS |
734efb46 | 1303 | /** |
e87821d1 | 1304 | * current_clocksource_show - sysfs interface for current clocksource |
734efb46 | 1305 | * @dev: unused |
b1b73d09 | 1306 | * @attr: unused |
734efb46 | 1307 | * @buf: char buffer to be filled with clocksource list |
1308 | * | |
1309 | * Provides sysfs interface for listing current clocksource. | |
1310 | */ | |
e87821d1 BW |
1311 | static ssize_t current_clocksource_show(struct device *dev, |
1312 | struct device_attribute *attr, | |
1313 | char *buf) | |
734efb46 | 1314 | { |
5e2cb101 | 1315 | ssize_t count = 0; |
734efb46 | 1316 | |
75c5158f | 1317 | mutex_lock(&clocksource_mutex); |
5e2cb101 | 1318 | count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); |
75c5158f | 1319 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1320 | |
5e2cb101 | 1321 | return count; |
734efb46 | 1322 | } |
1323 | ||
891292a7 | 1324 | ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt) |
29b54078 TG |
1325 | { |
1326 | size_t ret = cnt; | |
1327 | ||
1328 | /* strings from sysfs write are not 0 terminated! */ | |
1329 | if (!cnt || cnt >= CS_NAME_LEN) | |
1330 | return -EINVAL; | |
1331 | ||
1332 | /* strip of \n: */ | |
1333 | if (buf[cnt-1] == '\n') | |
1334 | cnt--; | |
1335 | if (cnt > 0) | |
1336 | memcpy(dst, buf, cnt); | |
1337 | dst[cnt] = 0; | |
1338 | return ret; | |
1339 | } | |
1340 | ||
734efb46 | 1341 | /** |
e87821d1 | 1342 | * current_clocksource_store - interface for manually overriding clocksource |
734efb46 | 1343 | * @dev: unused |
b1b73d09 | 1344 | * @attr: unused |
734efb46 | 1345 | * @buf: name of override clocksource |
1346 | * @count: length of buffer | |
1347 | * | |
1348 | * Takes input from sysfs interface for manually overriding the default | |
b71a8eb0 | 1349 | * clocksource selection. |
734efb46 | 1350 | */ |
e87821d1 BW |
1351 | static ssize_t current_clocksource_store(struct device *dev, |
1352 | struct device_attribute *attr, | |
1353 | const char *buf, size_t count) | |
734efb46 | 1354 | { |
233bcb41 | 1355 | ssize_t ret; |
734efb46 | 1356 | |
75c5158f | 1357 | mutex_lock(&clocksource_mutex); |
734efb46 | 1358 | |
03e13cf5 | 1359 | ret = sysfs_get_uname(buf, override_name, count); |
29b54078 TG |
1360 | if (ret >= 0) |
1361 | clocksource_select(); | |
734efb46 | 1362 | |
75c5158f | 1363 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1364 | |
1365 | return ret; | |
1366 | } | |
e87821d1 | 1367 | static DEVICE_ATTR_RW(current_clocksource); |
734efb46 | 1368 | |
7eaeb343 | 1369 | /** |
e87821d1 | 1370 | * unbind_clocksource_store - interface for manually unbinding clocksource |
7eaeb343 TG |
1371 | * @dev: unused |
1372 | * @attr: unused | |
1373 | * @buf: unused | |
1374 | * @count: length of buffer | |
1375 | * | |
1376 | * Takes input from sysfs interface for manually unbinding a clocksource. | |
1377 | */ | |
e87821d1 | 1378 | static ssize_t unbind_clocksource_store(struct device *dev, |
7eaeb343 TG |
1379 | struct device_attribute *attr, |
1380 | const char *buf, size_t count) | |
1381 | { | |
1382 | struct clocksource *cs; | |
1383 | char name[CS_NAME_LEN]; | |
233bcb41 | 1384 | ssize_t ret; |
7eaeb343 | 1385 | |
03e13cf5 | 1386 | ret = sysfs_get_uname(buf, name, count); |
7eaeb343 TG |
1387 | if (ret < 0) |
1388 | return ret; | |
1389 | ||
1390 | ret = -ENODEV; | |
1391 | mutex_lock(&clocksource_mutex); | |
1392 | list_for_each_entry(cs, &clocksource_list, list) { | |
1393 | if (strcmp(cs->name, name)) | |
1394 | continue; | |
1395 | ret = clocksource_unbind(cs); | |
1396 | break; | |
1397 | } | |
1398 | mutex_unlock(&clocksource_mutex); | |
1399 | ||
1400 | return ret ? ret : count; | |
1401 | } | |
e87821d1 | 1402 | static DEVICE_ATTR_WO(unbind_clocksource); |
7eaeb343 | 1403 | |
734efb46 | 1404 | /** |
e87821d1 | 1405 | * available_clocksource_show - sysfs interface for listing clocksource |
734efb46 | 1406 | * @dev: unused |
b1b73d09 | 1407 | * @attr: unused |
734efb46 | 1408 | * @buf: char buffer to be filled with clocksource list |
1409 | * | |
1410 | * Provides sysfs interface for listing registered clocksources | |
1411 | */ | |
e87821d1 BW |
1412 | static ssize_t available_clocksource_show(struct device *dev, |
1413 | struct device_attribute *attr, | |
1414 | char *buf) | |
734efb46 | 1415 | { |
2e197586 | 1416 | struct clocksource *src; |
5e2cb101 | 1417 | ssize_t count = 0; |
734efb46 | 1418 | |
75c5158f | 1419 | mutex_lock(&clocksource_mutex); |
2e197586 | 1420 | list_for_each_entry(src, &clocksource_list, list) { |
cd6d95d8 TG |
1421 | /* |
1422 | * Don't show non-HRES clocksource if the tick code is | |
1423 | * in one shot mode (highres=on or nohz=on) | |
1424 | */ | |
1425 | if (!tick_oneshot_mode_active() || | |
1426 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) | |
3f68535a | 1427 | count += snprintf(buf + count, |
5e2cb101 MX |
1428 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), |
1429 | "%s ", src->name); | |
734efb46 | 1430 | } |
75c5158f | 1431 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1432 | |
5e2cb101 MX |
1433 | count += snprintf(buf + count, |
1434 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); | |
734efb46 | 1435 | |
5e2cb101 | 1436 | return count; |
734efb46 | 1437 | } |
e87821d1 | 1438 | static DEVICE_ATTR_RO(available_clocksource); |
734efb46 | 1439 | |
27263e8d BW |
1440 | static struct attribute *clocksource_attrs[] = { |
1441 | &dev_attr_current_clocksource.attr, | |
1442 | &dev_attr_unbind_clocksource.attr, | |
1443 | &dev_attr_available_clocksource.attr, | |
1444 | NULL | |
1445 | }; | |
1446 | ATTRIBUTE_GROUPS(clocksource); | |
1447 | ||
d369a5d8 | 1448 | static struct bus_type clocksource_subsys = { |
af5ca3f4 | 1449 | .name = "clocksource", |
d369a5d8 | 1450 | .dev_name = "clocksource", |
734efb46 | 1451 | }; |
1452 | ||
d369a5d8 | 1453 | static struct device device_clocksource = { |
734efb46 | 1454 | .id = 0, |
d369a5d8 | 1455 | .bus = &clocksource_subsys, |
27263e8d | 1456 | .groups = clocksource_groups, |
734efb46 | 1457 | }; |
1458 | ||
ad596171 | 1459 | static int __init init_clocksource_sysfs(void) |
734efb46 | 1460 | { |
d369a5d8 | 1461 | int error = subsys_system_register(&clocksource_subsys, NULL); |
734efb46 | 1462 | |
1463 | if (!error) | |
d369a5d8 | 1464 | error = device_register(&device_clocksource); |
27263e8d | 1465 | |
734efb46 | 1466 | return error; |
1467 | } | |
1468 | ||
1469 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 1470 | #endif /* CONFIG_SYSFS */ |
734efb46 | 1471 | |
1472 | /** | |
1473 | * boot_override_clocksource - boot clock override | |
1474 | * @str: override name | |
1475 | * | |
1476 | * Takes a clocksource= boot argument and uses it | |
1477 | * as the clocksource override name. | |
1478 | */ | |
1479 | static int __init boot_override_clocksource(char* str) | |
1480 | { | |
75c5158f | 1481 | mutex_lock(&clocksource_mutex); |
734efb46 | 1482 | if (str) |
1483 | strlcpy(override_name, str, sizeof(override_name)); | |
75c5158f | 1484 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1485 | return 1; |
1486 | } | |
1487 | ||
1488 | __setup("clocksource=", boot_override_clocksource); | |
1489 | ||
1490 | /** | |
1491 | * boot_override_clock - Compatibility layer for deprecated boot option | |
1492 | * @str: override name | |
1493 | * | |
1494 | * DEPRECATED! Takes a clock= boot argument and uses it | |
1495 | * as the clocksource override name | |
1496 | */ | |
1497 | static int __init boot_override_clock(char* str) | |
1498 | { | |
5d0cf410 | 1499 | if (!strcmp(str, "pmtmr")) { |
45bbfe64 | 1500 | pr_warn("clock=pmtmr is deprecated - use clocksource=acpi_pm\n"); |
5d0cf410 | 1501 | return boot_override_clocksource("acpi_pm"); |
1502 | } | |
45bbfe64 | 1503 | pr_warn("clock= boot option is deprecated - use clocksource=xyz\n"); |
734efb46 | 1504 | return boot_override_clocksource(str); |
1505 | } | |
1506 | ||
1507 | __setup("clock=", boot_override_clock); |