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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 | |
d0304569 AH |
23 | static noinline u64 cycles_to_nsec_safe(struct clocksource *cs, u64 start, u64 end) |
24 | { | |
25 | u64 delta = clocksource_delta(end, start, cs->mask); | |
26 | ||
27 | if (likely(delta < cs->max_cycles)) | |
28 | return clocksource_cyc2ns(delta, cs->mult, cs->shift); | |
29 | ||
30 | return mul_u64_u32_shr(delta, cs->mult, cs->shift); | |
31 | } | |
32 | ||
7d2f944a TG |
33 | /** |
34 | * clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks | |
35 | * @mult: pointer to mult variable | |
36 | * @shift: pointer to shift variable | |
37 | * @from: frequency to convert from | |
38 | * @to: frequency to convert to | |
5fdade95 | 39 | * @maxsec: guaranteed runtime conversion range in seconds |
7d2f944a TG |
40 | * |
41 | * The function evaluates the shift/mult pair for the scaled math | |
42 | * operations of clocksources and clockevents. | |
43 | * | |
44 | * @to and @from are frequency values in HZ. For clock sources @to is | |
45 | * NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock | |
46 | * event @to is the counter frequency and @from is NSEC_PER_SEC. | |
47 | * | |
5fdade95 | 48 | * The @maxsec conversion range argument controls the time frame in |
7d2f944a TG |
49 | * seconds which must be covered by the runtime conversion with the |
50 | * calculated mult and shift factors. This guarantees that no 64bit | |
51 | * overflow happens when the input value of the conversion is | |
52 | * multiplied with the calculated mult factor. Larger ranges may | |
4bf07f65 | 53 | * reduce the conversion accuracy by choosing smaller mult and shift |
7d2f944a TG |
54 | * factors. |
55 | */ | |
56 | void | |
5fdade95 | 57 | clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 maxsec) |
7d2f944a TG |
58 | { |
59 | u64 tmp; | |
60 | u32 sft, sftacc= 32; | |
61 | ||
62 | /* | |
63 | * Calculate the shift factor which is limiting the conversion | |
64 | * range: | |
65 | */ | |
5fdade95 | 66 | tmp = ((u64)maxsec * from) >> 32; |
7d2f944a TG |
67 | while (tmp) { |
68 | tmp >>=1; | |
69 | sftacc--; | |
70 | } | |
71 | ||
72 | /* | |
73 | * Find the conversion shift/mult pair which has the best | |
74 | * accuracy and fits the maxsec conversion range: | |
75 | */ | |
76 | for (sft = 32; sft > 0; sft--) { | |
77 | tmp = (u64) to << sft; | |
b5776c4a | 78 | tmp += from / 2; |
7d2f944a TG |
79 | do_div(tmp, from); |
80 | if ((tmp >> sftacc) == 0) | |
81 | break; | |
82 | } | |
83 | *mult = tmp; | |
84 | *shift = sft; | |
85 | } | |
5304121a | 86 | EXPORT_SYMBOL_GPL(clocks_calc_mult_shift); |
7d2f944a | 87 | |
734efb46 | 88 | /*[Clocksource internal variables]--------- |
89 | * curr_clocksource: | |
f1b82746 | 90 | * currently selected clocksource. |
39232ed5 BW |
91 | * suspend_clocksource: |
92 | * used to calculate the suspend time. | |
734efb46 | 93 | * clocksource_list: |
94 | * linked list with the registered clocksources | |
75c5158f MS |
95 | * clocksource_mutex: |
96 | * protects manipulations to curr_clocksource and the clocksource_list | |
734efb46 | 97 | * override_name: |
98 | * Name of the user-specified clocksource. | |
99 | */ | |
f1b82746 | 100 | static struct clocksource *curr_clocksource; |
39232ed5 | 101 | static struct clocksource *suspend_clocksource; |
734efb46 | 102 | static LIST_HEAD(clocksource_list); |
75c5158f | 103 | static DEFINE_MUTEX(clocksource_mutex); |
29b54078 | 104 | static char override_name[CS_NAME_LEN]; |
54a6bc0b | 105 | static int finished_booting; |
39232ed5 | 106 | static u64 suspend_start; |
734efb46 | 107 | |
c37e85c1 PM |
108 | /* |
109 | * Interval: 0.5sec. | |
110 | */ | |
111 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
64464955 | 112 | #define WATCHDOG_INTERVAL_MAX_NS ((2 * WATCHDOG_INTERVAL) * (NSEC_PER_SEC / HZ)) |
c37e85c1 | 113 | |
2e27e793 PM |
114 | /* |
115 | * Threshold: 0.0312s, when doubled: 0.0625s. | |
116 | * Also a default for cs->uncertainty_margin when registering clocks. | |
117 | */ | |
118 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 5) | |
119 | ||
120 | /* | |
121 | * Maximum permissible delay between two readouts of the watchdog | |
122 | * clocksource surrounding a read of the clocksource being validated. | |
123 | * This delay could be due to SMIs, NMIs, or to VCPU preemptions. Used as | |
124 | * a lower bound for cs->uncertainty_margin values when registering clocks. | |
c37e85c1 PM |
125 | * |
126 | * The default of 500 parts per million is based on NTP's limits. | |
127 | * If a clocksource is good enough for NTP, it is good enough for us! | |
2e27e793 | 128 | */ |
fc153c1c WL |
129 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG_MAX_SKEW_US |
130 | #define MAX_SKEW_USEC CONFIG_CLOCKSOURCE_WATCHDOG_MAX_SKEW_US | |
131 | #else | |
c37e85c1 | 132 | #define MAX_SKEW_USEC (125 * WATCHDOG_INTERVAL / HZ) |
fc153c1c WL |
133 | #endif |
134 | ||
135 | #define WATCHDOG_MAX_SKEW (MAX_SKEW_USEC * NSEC_PER_USEC) | |
2e27e793 | 136 | |
5d8b34fd | 137 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
f79e0258 | 138 | static void clocksource_watchdog_work(struct work_struct *work); |
332962f2 | 139 | static void clocksource_select(void); |
f79e0258 | 140 | |
5d8b34fd TG |
141 | static LIST_HEAD(watchdog_list); |
142 | static struct clocksource *watchdog; | |
143 | static struct timer_list watchdog_timer; | |
f79e0258 | 144 | static DECLARE_WORK(watchdog_work, clocksource_watchdog_work); |
5d8b34fd | 145 | static DEFINE_SPINLOCK(watchdog_lock); |
fb63a0eb | 146 | static int watchdog_running; |
9fb60336 | 147 | static atomic_t watchdog_reset_pending; |
64464955 | 148 | static int64_t watchdog_max_interval; |
b52f52a0 | 149 | |
0f48b41f | 150 | static inline void clocksource_watchdog_lock(unsigned long *flags) |
2aae7bcf PZ |
151 | { |
152 | spin_lock_irqsave(&watchdog_lock, *flags); | |
153 | } | |
154 | ||
0f48b41f | 155 | static inline void clocksource_watchdog_unlock(unsigned long *flags) |
2aae7bcf PZ |
156 | { |
157 | spin_unlock_irqrestore(&watchdog_lock, *flags); | |
158 | } | |
159 | ||
e2c631ba PZ |
160 | static int clocksource_watchdog_kthread(void *data); |
161 | static void __clocksource_change_rating(struct clocksource *cs, int rating); | |
162 | ||
e2c631ba PZ |
163 | static void clocksource_watchdog_work(struct work_struct *work) |
164 | { | |
165 | /* | |
166 | * We cannot directly run clocksource_watchdog_kthread() here, because | |
167 | * clocksource_select() calls timekeeping_notify() which uses | |
168 | * stop_machine(). One cannot use stop_machine() from a workqueue() due | |
169 | * lock inversions wrt CPU hotplug. | |
170 | * | |
171 | * Also, we only ever run this work once or twice during the lifetime | |
172 | * of the kernel, so there is no point in creating a more permanent | |
173 | * kthread for this. | |
174 | * | |
175 | * If kthread_run fails the next watchdog scan over the | |
176 | * watchdog_list will find the unstable clock again. | |
177 | */ | |
178 | kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog"); | |
179 | } | |
180 | ||
7285dd7f | 181 | static void __clocksource_unstable(struct clocksource *cs) |
5d8b34fd | 182 | { |
5d8b34fd | 183 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); |
c55c87c8 | 184 | cs->flags |= CLOCK_SOURCE_UNSTABLE; |
12907fbb | 185 | |
cd2af07d | 186 | /* |
e2c631ba | 187 | * If the clocksource is registered clocksource_watchdog_kthread() will |
cd2af07d PZ |
188 | * re-rate and re-select. |
189 | */ | |
190 | if (list_empty(&cs->list)) { | |
191 | cs->rating = 0; | |
2aae7bcf | 192 | return; |
cd2af07d | 193 | } |
2aae7bcf | 194 | |
12907fbb TG |
195 | if (cs->mark_unstable) |
196 | cs->mark_unstable(cs); | |
197 | ||
e2c631ba | 198 | /* kick clocksource_watchdog_kthread() */ |
54a6bc0b TG |
199 | if (finished_booting) |
200 | schedule_work(&watchdog_work); | |
5d8b34fd TG |
201 | } |
202 | ||
7285dd7f TG |
203 | /** |
204 | * clocksource_mark_unstable - mark clocksource unstable via watchdog | |
205 | * @cs: clocksource to be marked unstable | |
206 | * | |
7dba33c6 | 207 | * This function is called by the x86 TSC code to mark clocksources as unstable; |
e2c631ba | 208 | * it defers demotion and re-selection to a kthread. |
7285dd7f TG |
209 | */ |
210 | void clocksource_mark_unstable(struct clocksource *cs) | |
211 | { | |
212 | unsigned long flags; | |
213 | ||
214 | spin_lock_irqsave(&watchdog_lock, flags); | |
215 | if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) { | |
2aae7bcf | 216 | if (!list_empty(&cs->list) && list_empty(&cs->wd_list)) |
7285dd7f TG |
217 | list_add(&cs->wd_list, &watchdog_list); |
218 | __clocksource_unstable(cs); | |
219 | } | |
220 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
221 | } | |
222 | ||
fa218f1c PM |
223 | static int verify_n_cpus = 8; |
224 | module_param(verify_n_cpus, int, 0644); | |
db3a34e1 | 225 | |
c86ff8c5 WL |
226 | enum wd_read_status { |
227 | WD_READ_SUCCESS, | |
228 | WD_READ_UNSTABLE, | |
229 | WD_READ_SKIP | |
230 | }; | |
231 | ||
232 | static enum wd_read_status cs_watchdog_read(struct clocksource *cs, u64 *csnow, u64 *wdnow) | |
db3a34e1 | 233 | { |
2ed08e4b | 234 | unsigned int nretries, max_retries; |
c86ff8c5 | 235 | int64_t wd_delay, wd_seq_delay; |
d0304569 | 236 | u64 wd_end, wd_end2; |
db3a34e1 | 237 | |
2ed08e4b FT |
238 | max_retries = clocksource_get_max_watchdog_retry(); |
239 | for (nretries = 0; nretries <= max_retries; nretries++) { | |
db3a34e1 PM |
240 | local_irq_disable(); |
241 | *wdnow = watchdog->read(watchdog); | |
242 | *csnow = cs->read(cs); | |
243 | wd_end = watchdog->read(watchdog); | |
c86ff8c5 | 244 | wd_end2 = watchdog->read(watchdog); |
db3a34e1 PM |
245 | local_irq_enable(); |
246 | ||
d0304569 | 247 | wd_delay = cycles_to_nsec_safe(watchdog, *wdnow, wd_end); |
db3a34e1 | 248 | if (wd_delay <= WATCHDOG_MAX_SKEW) { |
2ed08e4b | 249 | if (nretries > 1 || nretries >= max_retries) { |
db3a34e1 PM |
250 | pr_warn("timekeeping watchdog on CPU%d: %s retried %d times before success\n", |
251 | smp_processor_id(), watchdog->name, nretries); | |
252 | } | |
c86ff8c5 | 253 | return WD_READ_SUCCESS; |
db3a34e1 | 254 | } |
c86ff8c5 WL |
255 | |
256 | /* | |
257 | * Now compute delay in consecutive watchdog read to see if | |
258 | * there is too much external interferences that cause | |
259 | * significant delay in reading both clocksource and watchdog. | |
260 | * | |
261 | * If consecutive WD read-back delay > WATCHDOG_MAX_SKEW/2, | |
262 | * report system busy, reinit the watchdog and skip the current | |
263 | * watchdog test. | |
264 | */ | |
d0304569 | 265 | wd_seq_delay = cycles_to_nsec_safe(watchdog, wd_end, wd_end2); |
c86ff8c5 WL |
266 | if (wd_seq_delay > WATCHDOG_MAX_SKEW/2) |
267 | goto skip_test; | |
db3a34e1 PM |
268 | } |
269 | ||
f092eb34 PM |
270 | 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", |
271 | smp_processor_id(), cs->name, wd_delay, WATCHDOG_MAX_SKEW, wd_seq_delay, nretries, cs->name); | |
c86ff8c5 WL |
272 | return WD_READ_UNSTABLE; |
273 | ||
274 | skip_test: | |
275 | pr_info("timekeeping watchdog on CPU%d: %s wd-wd read-back delay of %lldns\n", | |
276 | smp_processor_id(), watchdog->name, wd_seq_delay); | |
277 | pr_info("wd-%s-wd read-back delay of %lldns, clock-skew test skipped!\n", | |
278 | cs->name, wd_delay); | |
279 | return WD_READ_SKIP; | |
db3a34e1 PM |
280 | } |
281 | ||
7560c02b PM |
282 | static u64 csnow_mid; |
283 | static cpumask_t cpus_ahead; | |
284 | static cpumask_t cpus_behind; | |
fa218f1c PM |
285 | static cpumask_t cpus_chosen; |
286 | ||
287 | static void clocksource_verify_choose_cpus(void) | |
288 | { | |
289 | int cpu, i, n = verify_n_cpus; | |
290 | ||
291 | if (n < 0) { | |
292 | /* Check all of the CPUs. */ | |
293 | cpumask_copy(&cpus_chosen, cpu_online_mask); | |
294 | cpumask_clear_cpu(smp_processor_id(), &cpus_chosen); | |
295 | return; | |
296 | } | |
297 | ||
298 | /* If no checking desired, or no other CPU to check, leave. */ | |
299 | cpumask_clear(&cpus_chosen); | |
300 | if (n == 0 || num_online_cpus() <= 1) | |
301 | return; | |
302 | ||
303 | /* Make sure to select at least one CPU other than the current CPU. */ | |
9b51d9d8 | 304 | cpu = cpumask_first(cpu_online_mask); |
fa218f1c PM |
305 | if (cpu == smp_processor_id()) |
306 | cpu = cpumask_next(cpu, cpu_online_mask); | |
307 | if (WARN_ON_ONCE(cpu >= nr_cpu_ids)) | |
308 | return; | |
309 | cpumask_set_cpu(cpu, &cpus_chosen); | |
310 | ||
311 | /* Force a sane value for the boot parameter. */ | |
312 | if (n > nr_cpu_ids) | |
313 | n = nr_cpu_ids; | |
314 | ||
315 | /* | |
316 | * Randomly select the specified number of CPUs. If the same | |
317 | * CPU is selected multiple times, that CPU is checked only once, | |
318 | * and no replacement CPU is selected. This gracefully handles | |
319 | * situations where verify_n_cpus is greater than the number of | |
320 | * CPUs that are currently online. | |
321 | */ | |
322 | for (i = 1; i < n; i++) { | |
8032bf12 | 323 | cpu = get_random_u32_below(nr_cpu_ids); |
fa218f1c PM |
324 | cpu = cpumask_next(cpu - 1, cpu_online_mask); |
325 | if (cpu >= nr_cpu_ids) | |
9b51d9d8 | 326 | cpu = cpumask_first(cpu_online_mask); |
fa218f1c PM |
327 | if (!WARN_ON_ONCE(cpu >= nr_cpu_ids)) |
328 | cpumask_set_cpu(cpu, &cpus_chosen); | |
329 | } | |
330 | ||
331 | /* Don't verify ourselves. */ | |
332 | cpumask_clear_cpu(smp_processor_id(), &cpus_chosen); | |
333 | } | |
7560c02b PM |
334 | |
335 | static void clocksource_verify_one_cpu(void *csin) | |
336 | { | |
337 | struct clocksource *cs = (struct clocksource *)csin; | |
338 | ||
339 | csnow_mid = cs->read(cs); | |
340 | } | |
341 | ||
1253b9b8 | 342 | void clocksource_verify_percpu(struct clocksource *cs) |
7560c02b PM |
343 | { |
344 | int64_t cs_nsec, cs_nsec_max = 0, cs_nsec_min = LLONG_MAX; | |
345 | u64 csnow_begin, csnow_end; | |
346 | int cpu, testcpu; | |
347 | s64 delta; | |
348 | ||
fa218f1c PM |
349 | if (verify_n_cpus == 0) |
350 | return; | |
7560c02b PM |
351 | cpumask_clear(&cpus_ahead); |
352 | cpumask_clear(&cpus_behind); | |
698429f9 | 353 | cpus_read_lock(); |
7560c02b | 354 | preempt_disable(); |
fa218f1c | 355 | clocksource_verify_choose_cpus(); |
8afbcaf8 | 356 | if (cpumask_empty(&cpus_chosen)) { |
fa218f1c | 357 | preempt_enable(); |
698429f9 | 358 | cpus_read_unlock(); |
fa218f1c PM |
359 | pr_warn("Not enough CPUs to check clocksource '%s'.\n", cs->name); |
360 | return; | |
361 | } | |
7560c02b | 362 | testcpu = smp_processor_id(); |
fa218f1c PM |
363 | pr_warn("Checking clocksource %s synchronization from CPU %d to CPUs %*pbl.\n", cs->name, testcpu, cpumask_pr_args(&cpus_chosen)); |
364 | for_each_cpu(cpu, &cpus_chosen) { | |
7560c02b PM |
365 | if (cpu == testcpu) |
366 | continue; | |
367 | csnow_begin = cs->read(cs); | |
368 | smp_call_function_single(cpu, clocksource_verify_one_cpu, cs, 1); | |
369 | csnow_end = cs->read(cs); | |
370 | delta = (s64)((csnow_mid - csnow_begin) & cs->mask); | |
371 | if (delta < 0) | |
372 | cpumask_set_cpu(cpu, &cpus_behind); | |
373 | delta = (csnow_end - csnow_mid) & cs->mask; | |
374 | if (delta < 0) | |
375 | cpumask_set_cpu(cpu, &cpus_ahead); | |
d0304569 | 376 | cs_nsec = cycles_to_nsec_safe(cs, csnow_begin, csnow_end); |
7560c02b PM |
377 | if (cs_nsec > cs_nsec_max) |
378 | cs_nsec_max = cs_nsec; | |
379 | if (cs_nsec < cs_nsec_min) | |
380 | cs_nsec_min = cs_nsec; | |
381 | } | |
382 | preempt_enable(); | |
698429f9 | 383 | cpus_read_unlock(); |
7560c02b PM |
384 | if (!cpumask_empty(&cpus_ahead)) |
385 | pr_warn(" CPUs %*pbl ahead of CPU %d for clocksource %s.\n", | |
386 | cpumask_pr_args(&cpus_ahead), testcpu, cs->name); | |
387 | if (!cpumask_empty(&cpus_behind)) | |
388 | pr_warn(" CPUs %*pbl behind CPU %d for clocksource %s.\n", | |
389 | cpumask_pr_args(&cpus_behind), testcpu, cs->name); | |
390 | if (!cpumask_empty(&cpus_ahead) || !cpumask_empty(&cpus_behind)) | |
391 | pr_warn(" CPU %d check durations %lldns - %lldns for clocksource %s.\n", | |
392 | testcpu, cs_nsec_min, cs_nsec_max, cs->name); | |
393 | } | |
1253b9b8 | 394 | EXPORT_SYMBOL_GPL(clocksource_verify_percpu); |
7560c02b | 395 | |
b7082cdf FT |
396 | static inline void clocksource_reset_watchdog(void) |
397 | { | |
398 | struct clocksource *cs; | |
399 | ||
400 | list_for_each_entry(cs, &watchdog_list, wd_list) | |
401 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
402 | } | |
403 | ||
404 | ||
e99e88a9 | 405 | static void clocksource_watchdog(struct timer_list *unused) |
5d8b34fd | 406 | { |
64464955 | 407 | int64_t wd_nsec, cs_nsec, interval; |
d0304569 | 408 | u64 csnow, wdnow, cslast, wdlast; |
9fb60336 | 409 | int next_cpu, reset_pending; |
db3a34e1 | 410 | struct clocksource *cs; |
c86ff8c5 | 411 | enum wd_read_status read_ret; |
b7082cdf | 412 | unsigned long extra_wait = 0; |
2e27e793 | 413 | u32 md; |
5d8b34fd TG |
414 | |
415 | spin_lock(&watchdog_lock); | |
fb63a0eb MS |
416 | if (!watchdog_running) |
417 | goto out; | |
5d8b34fd | 418 | |
9fb60336 TG |
419 | reset_pending = atomic_read(&watchdog_reset_pending); |
420 | ||
c55c87c8 MS |
421 | list_for_each_entry(cs, &watchdog_list, wd_list) { |
422 | ||
423 | /* Clocksource already marked unstable? */ | |
01548f4d | 424 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
54a6bc0b TG |
425 | if (finished_booting) |
426 | schedule_work(&watchdog_work); | |
c55c87c8 | 427 | continue; |
01548f4d | 428 | } |
c55c87c8 | 429 | |
c86ff8c5 WL |
430 | read_ret = cs_watchdog_read(cs, &csnow, &wdnow); |
431 | ||
b7082cdf FT |
432 | if (read_ret == WD_READ_UNSTABLE) { |
433 | /* Clock readout unreliable, so give it up. */ | |
434 | __clocksource_unstable(cs); | |
db3a34e1 PM |
435 | continue; |
436 | } | |
b52f52a0 | 437 | |
b7082cdf FT |
438 | /* |
439 | * When WD_READ_SKIP is returned, it means the system is likely | |
440 | * under very heavy load, where the latency of reading | |
441 | * watchdog/clocksource is very big, and affect the accuracy of | |
442 | * watchdog check. So give system some space and suspend the | |
443 | * watchdog check for 5 minutes. | |
444 | */ | |
445 | if (read_ret == WD_READ_SKIP) { | |
446 | /* | |
447 | * As the watchdog timer will be suspended, and | |
448 | * cs->last could keep unchanged for 5 minutes, reset | |
449 | * the counters. | |
450 | */ | |
451 | clocksource_reset_watchdog(); | |
452 | extra_wait = HZ * 300; | |
453 | break; | |
454 | } | |
455 | ||
8cf4e750 | 456 | /* Clocksource initialized ? */ |
9fb60336 TG |
457 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) || |
458 | atomic_read(&watchdog_reset_pending)) { | |
8cf4e750 | 459 | cs->flags |= CLOCK_SOURCE_WATCHDOG; |
b5199515 TG |
460 | cs->wd_last = wdnow; |
461 | cs->cs_last = csnow; | |
b52f52a0 TG |
462 | continue; |
463 | } | |
464 | ||
d0304569 AH |
465 | wd_nsec = cycles_to_nsec_safe(watchdog, cs->wd_last, wdnow); |
466 | cs_nsec = cycles_to_nsec_safe(cs, cs->cs_last, csnow); | |
0b046b21 JS |
467 | wdlast = cs->wd_last; /* save these in case we print them */ |
468 | cslast = cs->cs_last; | |
b5199515 TG |
469 | cs->cs_last = csnow; |
470 | cs->wd_last = wdnow; | |
471 | ||
9fb60336 TG |
472 | if (atomic_read(&watchdog_reset_pending)) |
473 | continue; | |
474 | ||
64464955 JW |
475 | /* |
476 | * The processing of timer softirqs can get delayed (usually | |
477 | * on account of ksoftirqd not getting to run in a timely | |
478 | * manner), which causes the watchdog interval to stretch. | |
479 | * Skew detection may fail for longer watchdog intervals | |
480 | * on account of fixed margins being used. | |
481 | * Some clocksources, e.g. acpi_pm, cannot tolerate | |
482 | * watchdog intervals longer than a few seconds. | |
483 | */ | |
484 | interval = max(cs_nsec, wd_nsec); | |
485 | if (unlikely(interval > WATCHDOG_INTERVAL_MAX_NS)) { | |
486 | if (system_state > SYSTEM_SCHEDULING && | |
487 | interval > 2 * watchdog_max_interval) { | |
488 | watchdog_max_interval = interval; | |
489 | pr_warn("Long readout interval, skipping watchdog check: cs_nsec: %lld wd_nsec: %lld\n", | |
490 | cs_nsec, wd_nsec); | |
491 | } | |
492 | watchdog_timer.expires = jiffies; | |
493 | continue; | |
494 | } | |
495 | ||
b5199515 | 496 | /* Check the deviation from the watchdog clocksource. */ |
2e27e793 PM |
497 | md = cs->uncertainty_margin + watchdog->uncertainty_margin; |
498 | if (abs(cs_nsec - wd_nsec) > md) { | |
e40806e9 PM |
499 | s64 cs_wd_msec; |
500 | s64 wd_msec; | |
dd029269 PM |
501 | u32 wd_rem; |
502 | ||
390dd67c SI |
503 | pr_warn("timekeeping watchdog on CPU%d: Marking clocksource '%s' as unstable because the skew is too large:\n", |
504 | smp_processor_id(), cs->name); | |
22a22383 FT |
505 | pr_warn(" '%s' wd_nsec: %lld wd_now: %llx wd_last: %llx mask: %llx\n", |
506 | watchdog->name, wd_nsec, wdnow, wdlast, watchdog->mask); | |
507 | pr_warn(" '%s' cs_nsec: %lld cs_now: %llx cs_last: %llx mask: %llx\n", | |
508 | cs->name, cs_nsec, csnow, cslast, cs->mask); | |
e40806e9 PM |
509 | cs_wd_msec = div_s64_rem(cs_nsec - wd_nsec, 1000 * 1000, &wd_rem); |
510 | wd_msec = div_s64_rem(wd_nsec, 1000 * 1000, &wd_rem); | |
dd029269 PM |
511 | pr_warn(" Clocksource '%s' skewed %lld ns (%lld ms) over watchdog '%s' interval of %lld ns (%lld ms)\n", |
512 | cs->name, cs_nsec - wd_nsec, cs_wd_msec, watchdog->name, wd_nsec, wd_msec); | |
fa218f1c PM |
513 | if (curr_clocksource == cs) |
514 | pr_warn(" '%s' is current clocksource.\n", cs->name); | |
515 | else if (curr_clocksource) | |
516 | pr_warn(" '%s' (not '%s') is current clocksource.\n", curr_clocksource->name, cs->name); | |
517 | else | |
518 | pr_warn(" No current clocksource.\n"); | |
0b046b21 | 519 | __clocksource_unstable(cs); |
8cf4e750 MS |
520 | continue; |
521 | } | |
522 | ||
b421b22b PZ |
523 | if (cs == curr_clocksource && cs->tick_stable) |
524 | cs->tick_stable(cs); | |
525 | ||
8cf4e750 MS |
526 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && |
527 | (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
528 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
332962f2 | 529 | /* Mark it valid for high-res. */ |
8cf4e750 | 530 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
332962f2 TG |
531 | |
532 | /* | |
533 | * clocksource_done_booting() will sort it if | |
534 | * finished_booting is not set yet. | |
535 | */ | |
536 | if (!finished_booting) | |
537 | continue; | |
538 | ||
8cf4e750 | 539 | /* |
332962f2 TG |
540 | * If this is not the current clocksource let |
541 | * the watchdog thread reselect it. Due to the | |
542 | * change to high res this clocksource might | |
543 | * be preferred now. If it is the current | |
544 | * clocksource let the tick code know about | |
545 | * that change. | |
8cf4e750 | 546 | */ |
332962f2 TG |
547 | if (cs != curr_clocksource) { |
548 | cs->flags |= CLOCK_SOURCE_RESELECT; | |
549 | schedule_work(&watchdog_work); | |
550 | } else { | |
551 | tick_clock_notify(); | |
552 | } | |
5d8b34fd TG |
553 | } |
554 | } | |
555 | ||
9fb60336 TG |
556 | /* |
557 | * We only clear the watchdog_reset_pending, when we did a | |
558 | * full cycle through all clocksources. | |
559 | */ | |
560 | if (reset_pending) | |
561 | atomic_dec(&watchdog_reset_pending); | |
562 | ||
c55c87c8 MS |
563 | /* |
564 | * Cycle through CPUs to check if the CPUs stay synchronized | |
565 | * to each other. | |
566 | */ | |
567 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); | |
568 | if (next_cpu >= nr_cpu_ids) | |
569 | next_cpu = cpumask_first(cpu_online_mask); | |
febac332 KK |
570 | |
571 | /* | |
572 | * Arm timer if not already pending: could race with concurrent | |
573 | * pair clocksource_stop_watchdog() clocksource_start_watchdog(). | |
574 | */ | |
575 | if (!timer_pending(&watchdog_timer)) { | |
b7082cdf | 576 | watchdog_timer.expires += WATCHDOG_INTERVAL + extra_wait; |
febac332 KK |
577 | add_timer_on(&watchdog_timer, next_cpu); |
578 | } | |
fb63a0eb | 579 | out: |
5d8b34fd TG |
580 | spin_unlock(&watchdog_lock); |
581 | } | |
0f8e8ef7 | 582 | |
fb63a0eb MS |
583 | static inline void clocksource_start_watchdog(void) |
584 | { | |
585 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) | |
586 | return; | |
e99e88a9 | 587 | timer_setup(&watchdog_timer, clocksource_watchdog, 0); |
fb63a0eb MS |
588 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; |
589 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); | |
590 | watchdog_running = 1; | |
591 | } | |
592 | ||
593 | static inline void clocksource_stop_watchdog(void) | |
594 | { | |
595 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) | |
596 | return; | |
597 | del_timer(&watchdog_timer); | |
598 | watchdog_running = 0; | |
599 | } | |
600 | ||
b52f52a0 TG |
601 | static void clocksource_resume_watchdog(void) |
602 | { | |
9fb60336 | 603 | atomic_inc(&watchdog_reset_pending); |
b52f52a0 TG |
604 | } |
605 | ||
fb63a0eb | 606 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
5d8b34fd | 607 | { |
5b9e886a PZ |
608 | INIT_LIST_HEAD(&cs->wd_list); |
609 | ||
5d8b34fd | 610 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { |
fb63a0eb | 611 | /* cs is a clocksource to be watched. */ |
5d8b34fd | 612 | list_add(&cs->wd_list, &watchdog_list); |
fb63a0eb | 613 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
948ac6d7 | 614 | } else { |
fb63a0eb | 615 | /* cs is a watchdog. */ |
948ac6d7 | 616 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
5d8b34fd | 617 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
bbf66d89 | 618 | } |
bbf66d89 VK |
619 | } |
620 | ||
621 | static void clocksource_select_watchdog(bool fallback) | |
622 | { | |
623 | struct clocksource *cs, *old_wd; | |
624 | unsigned long flags; | |
625 | ||
626 | spin_lock_irqsave(&watchdog_lock, flags); | |
627 | /* save current watchdog */ | |
628 | old_wd = watchdog; | |
629 | if (fallback) | |
630 | watchdog = NULL; | |
631 | ||
632 | list_for_each_entry(cs, &clocksource_list, list) { | |
633 | /* cs is a clocksource to be watched. */ | |
634 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) | |
635 | continue; | |
636 | ||
637 | /* Skip current if we were requested for a fallback. */ | |
638 | if (fallback && cs == old_wd) | |
639 | continue; | |
640 | ||
fb63a0eb | 641 | /* Pick the best watchdog. */ |
bbf66d89 | 642 | if (!watchdog || cs->rating > watchdog->rating) |
5d8b34fd | 643 | watchdog = cs; |
5d8b34fd | 644 | } |
bbf66d89 VK |
645 | /* If we failed to find a fallback restore the old one. */ |
646 | if (!watchdog) | |
647 | watchdog = old_wd; | |
648 | ||
649 | /* If we changed the watchdog we need to reset cycles. */ | |
650 | if (watchdog != old_wd) | |
651 | clocksource_reset_watchdog(); | |
652 | ||
fb63a0eb MS |
653 | /* Check if the watchdog timer needs to be started. */ |
654 | clocksource_start_watchdog(); | |
5d8b34fd TG |
655 | spin_unlock_irqrestore(&watchdog_lock, flags); |
656 | } | |
fb63a0eb MS |
657 | |
658 | static void clocksource_dequeue_watchdog(struct clocksource *cs) | |
659 | { | |
a89c7edb TG |
660 | if (cs != watchdog) { |
661 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
662 | /* cs is a watched clocksource. */ | |
663 | list_del_init(&cs->wd_list); | |
664 | /* Check if the watchdog timer needs to be stopped. */ | |
665 | clocksource_stop_watchdog(); | |
fb63a0eb MS |
666 | } |
667 | } | |
fb63a0eb MS |
668 | } |
669 | ||
e2c631ba | 670 | static int __clocksource_watchdog_kthread(void) |
c55c87c8 MS |
671 | { |
672 | struct clocksource *cs, *tmp; | |
673 | unsigned long flags; | |
332962f2 | 674 | int select = 0; |
c55c87c8 | 675 | |
7560c02b PM |
676 | /* Do any required per-CPU skew verification. */ |
677 | if (curr_clocksource && | |
678 | curr_clocksource->flags & CLOCK_SOURCE_UNSTABLE && | |
679 | curr_clocksource->flags & CLOCK_SOURCE_VERIFY_PERCPU) | |
680 | clocksource_verify_percpu(curr_clocksource); | |
681 | ||
c55c87c8 | 682 | spin_lock_irqsave(&watchdog_lock, flags); |
332962f2 | 683 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { |
c55c87c8 MS |
684 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
685 | list_del_init(&cs->wd_list); | |
2aae7bcf | 686 | __clocksource_change_rating(cs, 0); |
332962f2 TG |
687 | select = 1; |
688 | } | |
689 | if (cs->flags & CLOCK_SOURCE_RESELECT) { | |
690 | cs->flags &= ~CLOCK_SOURCE_RESELECT; | |
691 | select = 1; | |
c55c87c8 | 692 | } |
332962f2 | 693 | } |
c55c87c8 MS |
694 | /* Check if the watchdog timer needs to be stopped. */ |
695 | clocksource_stop_watchdog(); | |
6ea41d25 TG |
696 | spin_unlock_irqrestore(&watchdog_lock, flags); |
697 | ||
332962f2 TG |
698 | return select; |
699 | } | |
700 | ||
e2c631ba | 701 | static int clocksource_watchdog_kthread(void *data) |
332962f2 TG |
702 | { |
703 | mutex_lock(&clocksource_mutex); | |
e2c631ba | 704 | if (__clocksource_watchdog_kthread()) |
332962f2 | 705 | clocksource_select(); |
d0981a1b | 706 | mutex_unlock(&clocksource_mutex); |
e2c631ba | 707 | return 0; |
c55c87c8 MS |
708 | } |
709 | ||
7eaeb343 TG |
710 | static bool clocksource_is_watchdog(struct clocksource *cs) |
711 | { | |
712 | return cs == watchdog; | |
713 | } | |
714 | ||
fb63a0eb MS |
715 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
716 | ||
717 | static void clocksource_enqueue_watchdog(struct clocksource *cs) | |
5d8b34fd TG |
718 | { |
719 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
720 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
721 | } | |
b52f52a0 | 722 | |
bbf66d89 | 723 | static void clocksource_select_watchdog(bool fallback) { } |
fb63a0eb | 724 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
b52f52a0 | 725 | static inline void clocksource_resume_watchdog(void) { } |
e2c631ba | 726 | static inline int __clocksource_watchdog_kthread(void) { return 0; } |
7eaeb343 | 727 | static bool clocksource_is_watchdog(struct clocksource *cs) { return false; } |
397bbf6d | 728 | void clocksource_mark_unstable(struct clocksource *cs) { } |
fb63a0eb | 729 | |
db6f9e55 MM |
730 | static inline void clocksource_watchdog_lock(unsigned long *flags) { } |
731 | static inline void clocksource_watchdog_unlock(unsigned long *flags) { } | |
2aae7bcf | 732 | |
fb63a0eb | 733 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
5d8b34fd | 734 | |
39232ed5 BW |
735 | static bool clocksource_is_suspend(struct clocksource *cs) |
736 | { | |
737 | return cs == suspend_clocksource; | |
738 | } | |
739 | ||
740 | static void __clocksource_suspend_select(struct clocksource *cs) | |
741 | { | |
742 | /* | |
743 | * Skip the clocksource which will be stopped in suspend state. | |
744 | */ | |
745 | if (!(cs->flags & CLOCK_SOURCE_SUSPEND_NONSTOP)) | |
746 | return; | |
747 | ||
748 | /* | |
749 | * The nonstop clocksource can be selected as the suspend clocksource to | |
750 | * calculate the suspend time, so it should not supply suspend/resume | |
751 | * interfaces to suspend the nonstop clocksource when system suspends. | |
752 | */ | |
753 | if (cs->suspend || cs->resume) { | |
754 | pr_warn("Nonstop clocksource %s should not supply suspend/resume interfaces\n", | |
755 | cs->name); | |
756 | } | |
757 | ||
758 | /* Pick the best rating. */ | |
759 | if (!suspend_clocksource || cs->rating > suspend_clocksource->rating) | |
760 | suspend_clocksource = cs; | |
761 | } | |
762 | ||
763 | /** | |
764 | * clocksource_suspend_select - Select the best clocksource for suspend timing | |
765 | * @fallback: if select a fallback clocksource | |
766 | */ | |
767 | static void clocksource_suspend_select(bool fallback) | |
768 | { | |
769 | struct clocksource *cs, *old_suspend; | |
770 | ||
771 | old_suspend = suspend_clocksource; | |
772 | if (fallback) | |
773 | suspend_clocksource = NULL; | |
774 | ||
775 | list_for_each_entry(cs, &clocksource_list, list) { | |
776 | /* Skip current if we were requested for a fallback. */ | |
777 | if (fallback && cs == old_suspend) | |
778 | continue; | |
779 | ||
780 | __clocksource_suspend_select(cs); | |
781 | } | |
782 | } | |
783 | ||
784 | /** | |
785 | * clocksource_start_suspend_timing - Start measuring the suspend timing | |
786 | * @cs: current clocksource from timekeeping | |
787 | * @start_cycles: current cycles from timekeeping | |
788 | * | |
789 | * This function will save the start cycle values of suspend timer to calculate | |
790 | * the suspend time when resuming system. | |
791 | * | |
792 | * This function is called late in the suspend process from timekeeping_suspend(), | |
4bf07f65 | 793 | * that means processes are frozen, non-boot cpus and interrupts are disabled |
39232ed5 BW |
794 | * now. It is therefore possible to start the suspend timer without taking the |
795 | * clocksource mutex. | |
796 | */ | |
797 | void clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles) | |
798 | { | |
799 | if (!suspend_clocksource) | |
800 | return; | |
801 | ||
802 | /* | |
803 | * If current clocksource is the suspend timer, we should use the | |
804 | * tkr_mono.cycle_last value as suspend_start to avoid same reading | |
805 | * from suspend timer. | |
806 | */ | |
807 | if (clocksource_is_suspend(cs)) { | |
808 | suspend_start = start_cycles; | |
809 | return; | |
810 | } | |
811 | ||
812 | if (suspend_clocksource->enable && | |
813 | suspend_clocksource->enable(suspend_clocksource)) { | |
814 | pr_warn_once("Failed to enable the non-suspend-able clocksource.\n"); | |
815 | return; | |
816 | } | |
817 | ||
818 | suspend_start = suspend_clocksource->read(suspend_clocksource); | |
819 | } | |
820 | ||
821 | /** | |
822 | * clocksource_stop_suspend_timing - Stop measuring the suspend timing | |
823 | * @cs: current clocksource from timekeeping | |
824 | * @cycle_now: current cycles from timekeeping | |
825 | * | |
826 | * This function will calculate the suspend time from suspend timer. | |
827 | * | |
828 | * Returns nanoseconds since suspend started, 0 if no usable suspend clocksource. | |
829 | * | |
830 | * This function is called early in the resume process from timekeeping_resume(), | |
831 | * that means there is only one cpu, no processes are running and the interrupts | |
832 | * are disabled. It is therefore possible to stop the suspend timer without | |
833 | * taking the clocksource mutex. | |
834 | */ | |
835 | u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 cycle_now) | |
836 | { | |
d0304569 | 837 | u64 now, nsec = 0; |
39232ed5 BW |
838 | |
839 | if (!suspend_clocksource) | |
840 | return 0; | |
841 | ||
842 | /* | |
843 | * If current clocksource is the suspend timer, we should use the | |
844 | * tkr_mono.cycle_last value from timekeeping as current cycle to | |
845 | * avoid same reading from suspend timer. | |
846 | */ | |
847 | if (clocksource_is_suspend(cs)) | |
848 | now = cycle_now; | |
849 | else | |
850 | now = suspend_clocksource->read(suspend_clocksource); | |
851 | ||
d0304569 AH |
852 | if (now > suspend_start) |
853 | nsec = cycles_to_nsec_safe(suspend_clocksource, suspend_start, now); | |
39232ed5 BW |
854 | |
855 | /* | |
856 | * Disable the suspend timer to save power if current clocksource is | |
857 | * not the suspend timer. | |
858 | */ | |
859 | if (!clocksource_is_suspend(cs) && suspend_clocksource->disable) | |
860 | suspend_clocksource->disable(suspend_clocksource); | |
861 | ||
862 | return nsec; | |
863 | } | |
864 | ||
c54a42b1 MD |
865 | /** |
866 | * clocksource_suspend - suspend the clocksource(s) | |
867 | */ | |
868 | void clocksource_suspend(void) | |
869 | { | |
870 | struct clocksource *cs; | |
871 | ||
872 | list_for_each_entry_reverse(cs, &clocksource_list, list) | |
873 | if (cs->suspend) | |
874 | cs->suspend(cs); | |
875 | } | |
876 | ||
b52f52a0 TG |
877 | /** |
878 | * clocksource_resume - resume the clocksource(s) | |
879 | */ | |
880 | void clocksource_resume(void) | |
881 | { | |
2e197586 | 882 | struct clocksource *cs; |
b52f52a0 | 883 | |
75c5158f | 884 | list_for_each_entry(cs, &clocksource_list, list) |
b52f52a0 | 885 | if (cs->resume) |
17622339 | 886 | cs->resume(cs); |
b52f52a0 TG |
887 | |
888 | clocksource_resume_watchdog(); | |
b52f52a0 TG |
889 | } |
890 | ||
7c3078b6 JW |
891 | /** |
892 | * clocksource_touch_watchdog - Update watchdog | |
893 | * | |
894 | * Update the watchdog after exception contexts such as kgdb so as not | |
7b7422a5 TG |
895 | * to incorrectly trip the watchdog. This might fail when the kernel |
896 | * was stopped in code which holds watchdog_lock. | |
7c3078b6 JW |
897 | */ |
898 | void clocksource_touch_watchdog(void) | |
899 | { | |
900 | clocksource_resume_watchdog(); | |
901 | } | |
902 | ||
d65670a7 JS |
903 | /** |
904 | * clocksource_max_adjustment- Returns max adjustment amount | |
905 | * @cs: Pointer to clocksource | |
906 | * | |
907 | */ | |
908 | static u32 clocksource_max_adjustment(struct clocksource *cs) | |
909 | { | |
910 | u64 ret; | |
911 | /* | |
88b28adf | 912 | * We won't try to correct for more than 11% adjustments (110,000 ppm), |
d65670a7 JS |
913 | */ |
914 | ret = (u64)cs->mult * 11; | |
915 | do_div(ret,100); | |
916 | return (u32)ret; | |
917 | } | |
918 | ||
98962465 | 919 | /** |
87d8b9eb SB |
920 | * clocks_calc_max_nsecs - Returns maximum nanoseconds that can be converted |
921 | * @mult: cycle to nanosecond multiplier | |
922 | * @shift: cycle to nanosecond divisor (power of two) | |
923 | * @maxadj: maximum adjustment value to mult (~11%) | |
924 | * @mask: bitmask for two's complement subtraction of non 64 bit counters | |
fb82fe2f JS |
925 | * @max_cyc: maximum cycle value before potential overflow (does not include |
926 | * any safety margin) | |
362fde04 | 927 | * |
8e56f33f JS |
928 | * NOTE: This function includes a safety margin of 50%, in other words, we |
929 | * return half the number of nanoseconds the hardware counter can technically | |
930 | * cover. This is done so that we can potentially detect problems caused by | |
931 | * delayed timers or bad hardware, which might result in time intervals that | |
571af55a | 932 | * are larger than what the math used can handle without overflows. |
98962465 | 933 | */ |
fb82fe2f | 934 | u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cyc) |
98962465 JH |
935 | { |
936 | u64 max_nsecs, max_cycles; | |
937 | ||
938 | /* | |
939 | * Calculate the maximum number of cycles that we can pass to the | |
6086e346 | 940 | * cyc2ns() function without overflowing a 64-bit result. |
98962465 | 941 | */ |
6086e346 JS |
942 | max_cycles = ULLONG_MAX; |
943 | do_div(max_cycles, mult+maxadj); | |
98962465 JH |
944 | |
945 | /* | |
946 | * The actual maximum number of cycles we can defer the clocksource is | |
87d8b9eb | 947 | * determined by the minimum of max_cycles and mask. |
d65670a7 JS |
948 | * Note: Here we subtract the maxadj to make sure we don't sleep for |
949 | * too long if there's a large negative adjustment. | |
98962465 | 950 | */ |
87d8b9eb SB |
951 | max_cycles = min(max_cycles, mask); |
952 | max_nsecs = clocksource_cyc2ns(max_cycles, mult - maxadj, shift); | |
953 | ||
fb82fe2f JS |
954 | /* return the max_cycles value as well if requested */ |
955 | if (max_cyc) | |
956 | *max_cyc = max_cycles; | |
957 | ||
362fde04 JS |
958 | /* Return 50% of the actual maximum, so we can detect bad values */ |
959 | max_nsecs >>= 1; | |
960 | ||
87d8b9eb SB |
961 | return max_nsecs; |
962 | } | |
963 | ||
964 | /** | |
fb82fe2f JS |
965 | * clocksource_update_max_deferment - Updates the clocksource max_idle_ns & max_cycles |
966 | * @cs: Pointer to clocksource to be updated | |
87d8b9eb SB |
967 | * |
968 | */ | |
fb82fe2f | 969 | static inline void clocksource_update_max_deferment(struct clocksource *cs) |
87d8b9eb | 970 | { |
fb82fe2f JS |
971 | cs->max_idle_ns = clocks_calc_max_nsecs(cs->mult, cs->shift, |
972 | cs->maxadj, cs->mask, | |
973 | &cs->max_cycles); | |
98962465 JH |
974 | } |
975 | ||
f5a2e343 | 976 | static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur) |
5d33b883 TG |
977 | { |
978 | struct clocksource *cs; | |
979 | ||
980 | if (!finished_booting || list_empty(&clocksource_list)) | |
981 | return NULL; | |
982 | ||
983 | /* | |
984 | * We pick the clocksource with the highest rating. If oneshot | |
985 | * mode is active, we pick the highres valid clocksource with | |
986 | * the best rating. | |
987 | */ | |
988 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
989 | if (skipcur && cs == curr_clocksource) |
990 | continue; | |
5d33b883 TG |
991 | if (oneshot && !(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES)) |
992 | continue; | |
993 | return cs; | |
994 | } | |
995 | return NULL; | |
996 | } | |
997 | ||
f5a2e343 | 998 | static void __clocksource_select(bool skipcur) |
734efb46 | 999 | { |
5d33b883 | 1000 | bool oneshot = tick_oneshot_mode_active(); |
f1b82746 | 1001 | struct clocksource *best, *cs; |
5d8b34fd | 1002 | |
5d33b883 | 1003 | /* Find the best suitable clocksource */ |
f5a2e343 | 1004 | best = clocksource_find_best(oneshot, skipcur); |
5d33b883 | 1005 | if (!best) |
f1b82746 | 1006 | return; |
5d33b883 | 1007 | |
7f852afe BW |
1008 | if (!strlen(override_name)) |
1009 | goto found; | |
1010 | ||
f1b82746 MS |
1011 | /* Check for the override clocksource. */ |
1012 | list_for_each_entry(cs, &clocksource_list, list) { | |
f5a2e343 TG |
1013 | if (skipcur && cs == curr_clocksource) |
1014 | continue; | |
f1b82746 MS |
1015 | if (strcmp(cs->name, override_name) != 0) |
1016 | continue; | |
1017 | /* | |
1018 | * Check to make sure we don't switch to a non-highres | |
1019 | * capable clocksource if the tick code is in oneshot | |
1020 | * mode (highres or nohz) | |
1021 | */ | |
5d33b883 | 1022 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && oneshot) { |
f1b82746 | 1023 | /* Override clocksource cannot be used. */ |
36374583 KW |
1024 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
1025 | pr_warn("Override clocksource %s is unstable and not HRT compatible - cannot switch while in HRT/NOHZ mode\n", | |
1026 | cs->name); | |
1027 | override_name[0] = 0; | |
1028 | } else { | |
1029 | /* | |
1030 | * The override cannot be currently verified. | |
1031 | * Deferring to let the watchdog check. | |
1032 | */ | |
1033 | pr_info("Override clocksource %s is not currently HRT compatible - deferring\n", | |
1034 | cs->name); | |
1035 | } | |
f1b82746 MS |
1036 | } else |
1037 | /* Override clocksource can be used. */ | |
1038 | best = cs; | |
1039 | break; | |
1040 | } | |
ba919d1c | 1041 | |
7f852afe | 1042 | found: |
ba919d1c TG |
1043 | if (curr_clocksource != best && !timekeeping_notify(best)) { |
1044 | pr_info("Switched to clocksource %s\n", best->name); | |
75c5158f | 1045 | curr_clocksource = best; |
75c5158f | 1046 | } |
f1b82746 | 1047 | } |
734efb46 | 1048 | |
f5a2e343 TG |
1049 | /** |
1050 | * clocksource_select - Select the best clocksource available | |
1051 | * | |
1052 | * Private function. Must hold clocksource_mutex when called. | |
1053 | * | |
1054 | * Select the clocksource with the best rating, or the clocksource, | |
1055 | * which is selected by userspace override. | |
1056 | */ | |
1057 | static void clocksource_select(void) | |
1058 | { | |
cfed432d | 1059 | __clocksource_select(false); |
f5a2e343 TG |
1060 | } |
1061 | ||
7eaeb343 TG |
1062 | static void clocksource_select_fallback(void) |
1063 | { | |
cfed432d | 1064 | __clocksource_select(true); |
7eaeb343 TG |
1065 | } |
1066 | ||
75c5158f MS |
1067 | /* |
1068 | * clocksource_done_booting - Called near the end of core bootup | |
1069 | * | |
1070 | * Hack to avoid lots of clocksource churn at boot time. | |
1071 | * We use fs_initcall because we want this to start before | |
1072 | * device_initcall but after subsys_initcall. | |
1073 | */ | |
1074 | static int __init clocksource_done_booting(void) | |
1075 | { | |
ad6759fb | 1076 | mutex_lock(&clocksource_mutex); |
1077 | curr_clocksource = clocksource_default_clock(); | |
75c5158f | 1078 | finished_booting = 1; |
54a6bc0b TG |
1079 | /* |
1080 | * Run the watchdog first to eliminate unstable clock sources | |
1081 | */ | |
e2c631ba | 1082 | __clocksource_watchdog_kthread(); |
75c5158f | 1083 | clocksource_select(); |
e6c73305 | 1084 | mutex_unlock(&clocksource_mutex); |
75c5158f MS |
1085 | return 0; |
1086 | } | |
1087 | fs_initcall(clocksource_done_booting); | |
1088 | ||
92c7e002 TG |
1089 | /* |
1090 | * Enqueue the clocksource sorted by rating | |
734efb46 | 1091 | */ |
f1b82746 | 1092 | static void clocksource_enqueue(struct clocksource *cs) |
734efb46 | 1093 | { |
f1b82746 MS |
1094 | struct list_head *entry = &clocksource_list; |
1095 | struct clocksource *tmp; | |
92c7e002 | 1096 | |
0fb71d34 | 1097 | list_for_each_entry(tmp, &clocksource_list, list) { |
92c7e002 | 1098 | /* Keep track of the place, where to insert */ |
0fb71d34 MH |
1099 | if (tmp->rating < cs->rating) |
1100 | break; | |
1101 | entry = &tmp->list; | |
1102 | } | |
f1b82746 | 1103 | list_add(&cs->list, entry); |
734efb46 | 1104 | } |
1105 | ||
d7e81c26 | 1106 | /** |
fba9e072 | 1107 | * __clocksource_update_freq_scale - Used update clocksource with new freq |
b1b73d09 | 1108 | * @cs: clocksource to be registered |
d7e81c26 JS |
1109 | * @scale: Scale factor multiplied against freq to get clocksource hz |
1110 | * @freq: clocksource frequency (cycles per second) divided by scale | |
1111 | * | |
852db46d | 1112 | * This should only be called from the clocksource->enable() method. |
d7e81c26 JS |
1113 | * |
1114 | * This *SHOULD NOT* be called directly! Please use the | |
fba9e072 JS |
1115 | * __clocksource_update_freq_hz() or __clocksource_update_freq_khz() helper |
1116 | * functions. | |
d7e81c26 | 1117 | */ |
fba9e072 | 1118 | void __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq) |
d7e81c26 | 1119 | { |
c0e299b1 | 1120 | u64 sec; |
f8935983 | 1121 | |
d7e81c26 | 1122 | /* |
f8935983 JS |
1123 | * Default clocksources are *special* and self-define their mult/shift. |
1124 | * But, you're not special, so you should specify a freq value. | |
d7e81c26 | 1125 | */ |
f8935983 JS |
1126 | if (freq) { |
1127 | /* | |
1128 | * Calc the maximum number of seconds which we can run before | |
1129 | * wrapping around. For clocksources which have a mask > 32-bit | |
1130 | * we need to limit the max sleep time to have a good | |
1131 | * conversion precision. 10 minutes is still a reasonable | |
1132 | * amount. That results in a shift value of 24 for a | |
1133 | * clocksource with mask >= 40-bit and f >= 4GHz. That maps to | |
1134 | * ~ 0.06ppm granularity for NTP. | |
1135 | */ | |
1136 | sec = cs->mask; | |
1137 | do_div(sec, freq); | |
1138 | do_div(sec, scale); | |
1139 | if (!sec) | |
1140 | sec = 1; | |
1141 | else if (sec > 600 && cs->mask > UINT_MAX) | |
1142 | sec = 600; | |
1143 | ||
1144 | clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, | |
1145 | NSEC_PER_SEC / scale, sec * scale); | |
1146 | } | |
2e27e793 PM |
1147 | |
1148 | /* | |
1149 | * If the uncertainty margin is not specified, calculate it. | |
1150 | * If both scale and freq are non-zero, calculate the clock | |
1151 | * period, but bound below at 2*WATCHDOG_MAX_SKEW. However, | |
1152 | * if either of scale or freq is zero, be very conservative and | |
1153 | * take the tens-of-milliseconds WATCHDOG_THRESHOLD value for the | |
1154 | * uncertainty margin. Allow stupidly small uncertainty margins | |
1155 | * to be specified by the caller for testing purposes, but warn | |
1156 | * to discourage production use of this capability. | |
1157 | */ | |
1158 | if (scale && freq && !cs->uncertainty_margin) { | |
1159 | cs->uncertainty_margin = NSEC_PER_SEC / (scale * freq); | |
1160 | if (cs->uncertainty_margin < 2 * WATCHDOG_MAX_SKEW) | |
1161 | cs->uncertainty_margin = 2 * WATCHDOG_MAX_SKEW; | |
1162 | } else if (!cs->uncertainty_margin) { | |
1163 | cs->uncertainty_margin = WATCHDOG_THRESHOLD; | |
1164 | } | |
1165 | WARN_ON_ONCE(cs->uncertainty_margin < 2 * WATCHDOG_MAX_SKEW); | |
1166 | ||
d65670a7 | 1167 | /* |
362fde04 JS |
1168 | * Ensure clocksources that have large 'mult' values don't overflow |
1169 | * when adjusted. | |
d65670a7 JS |
1170 | */ |
1171 | cs->maxadj = clocksource_max_adjustment(cs); | |
f8935983 JS |
1172 | while (freq && ((cs->mult + cs->maxadj < cs->mult) |
1173 | || (cs->mult - cs->maxadj > cs->mult))) { | |
d65670a7 JS |
1174 | cs->mult >>= 1; |
1175 | cs->shift--; | |
1176 | cs->maxadj = clocksource_max_adjustment(cs); | |
1177 | } | |
1178 | ||
f8935983 JS |
1179 | /* |
1180 | * Only warn for *special* clocksources that self-define | |
1181 | * their mult/shift values and don't specify a freq. | |
1182 | */ | |
1183 | WARN_ONCE(cs->mult + cs->maxadj < cs->mult, | |
1184 | "timekeeping: Clocksource %s might overflow on 11%% adjustment\n", | |
1185 | cs->name); | |
1186 | ||
fb82fe2f | 1187 | clocksource_update_max_deferment(cs); |
8cc8c525 | 1188 | |
45bbfe64 JP |
1189 | pr_info("%s: mask: 0x%llx max_cycles: 0x%llx, max_idle_ns: %lld ns\n", |
1190 | cs->name, cs->mask, cs->max_cycles, cs->max_idle_ns); | |
852db46d | 1191 | } |
fba9e072 | 1192 | EXPORT_SYMBOL_GPL(__clocksource_update_freq_scale); |
852db46d JS |
1193 | |
1194 | /** | |
1195 | * __clocksource_register_scale - Used to install new clocksources | |
b1b73d09 | 1196 | * @cs: clocksource to be registered |
852db46d JS |
1197 | * @scale: Scale factor multiplied against freq to get clocksource hz |
1198 | * @freq: clocksource frequency (cycles per second) divided by scale | |
1199 | * | |
1200 | * Returns -EBUSY if registration fails, zero otherwise. | |
1201 | * | |
1202 | * This *SHOULD NOT* be called directly! Please use the | |
1203 | * clocksource_register_hz() or clocksource_register_khz helper functions. | |
1204 | */ | |
1205 | int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) | |
1206 | { | |
2aae7bcf | 1207 | unsigned long flags; |
852db46d | 1208 | |
d67f34c1 TG |
1209 | clocksource_arch_init(cs); |
1210 | ||
b2c67cbe TG |
1211 | if (WARN_ON_ONCE((unsigned int)cs->id >= CSID_MAX)) |
1212 | cs->id = CSID_GENERIC; | |
5d51bee7 TG |
1213 | if (cs->vdso_clock_mode < 0 || |
1214 | cs->vdso_clock_mode >= VDSO_CLOCKMODE_MAX) { | |
1215 | pr_warn("clocksource %s registered with invalid VDSO mode %d. Disabling VDSO support.\n", | |
1216 | cs->name, cs->vdso_clock_mode); | |
1217 | cs->vdso_clock_mode = VDSO_CLOCKMODE_NONE; | |
1218 | } | |
5d51bee7 | 1219 | |
b595076a | 1220 | /* Initialize mult/shift and max_idle_ns */ |
fba9e072 | 1221 | __clocksource_update_freq_scale(cs, scale, freq); |
d7e81c26 | 1222 | |
be278e98 | 1223 | /* Add clocksource to the clocksource list */ |
d7e81c26 | 1224 | mutex_lock(&clocksource_mutex); |
2aae7bcf PZ |
1225 | |
1226 | clocksource_watchdog_lock(&flags); | |
d7e81c26 | 1227 | clocksource_enqueue(cs); |
d7e81c26 | 1228 | clocksource_enqueue_watchdog(cs); |
2aae7bcf PZ |
1229 | clocksource_watchdog_unlock(&flags); |
1230 | ||
e05b2efb | 1231 | clocksource_select(); |
bbf66d89 | 1232 | clocksource_select_watchdog(false); |
39232ed5 | 1233 | __clocksource_suspend_select(cs); |
d7e81c26 JS |
1234 | mutex_unlock(&clocksource_mutex); |
1235 | return 0; | |
1236 | } | |
1237 | EXPORT_SYMBOL_GPL(__clocksource_register_scale); | |
1238 | ||
d0981a1b TG |
1239 | static void __clocksource_change_rating(struct clocksource *cs, int rating) |
1240 | { | |
1241 | list_del(&cs->list); | |
1242 | cs->rating = rating; | |
1243 | clocksource_enqueue(cs); | |
d0981a1b TG |
1244 | } |
1245 | ||
734efb46 | 1246 | /** |
92c7e002 | 1247 | * clocksource_change_rating - Change the rating of a registered clocksource |
b1b73d09 KK |
1248 | * @cs: clocksource to be changed |
1249 | * @rating: new rating | |
734efb46 | 1250 | */ |
92c7e002 | 1251 | void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb46 | 1252 | { |
2aae7bcf PZ |
1253 | unsigned long flags; |
1254 | ||
75c5158f | 1255 | mutex_lock(&clocksource_mutex); |
2aae7bcf | 1256 | clocksource_watchdog_lock(&flags); |
d0981a1b | 1257 | __clocksource_change_rating(cs, rating); |
2aae7bcf PZ |
1258 | clocksource_watchdog_unlock(&flags); |
1259 | ||
332962f2 | 1260 | clocksource_select(); |
bbf66d89 | 1261 | clocksource_select_watchdog(false); |
39232ed5 | 1262 | clocksource_suspend_select(false); |
75c5158f | 1263 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1264 | } |
fb63a0eb | 1265 | EXPORT_SYMBOL(clocksource_change_rating); |
734efb46 | 1266 | |
7eaeb343 TG |
1267 | /* |
1268 | * Unbind clocksource @cs. Called with clocksource_mutex held | |
1269 | */ | |
1270 | static int clocksource_unbind(struct clocksource *cs) | |
1271 | { | |
2aae7bcf PZ |
1272 | unsigned long flags; |
1273 | ||
bbf66d89 VK |
1274 | if (clocksource_is_watchdog(cs)) { |
1275 | /* Select and try to install a replacement watchdog. */ | |
1276 | clocksource_select_watchdog(true); | |
1277 | if (clocksource_is_watchdog(cs)) | |
1278 | return -EBUSY; | |
1279 | } | |
7eaeb343 TG |
1280 | |
1281 | if (cs == curr_clocksource) { | |
1282 | /* Select and try to install a replacement clock source */ | |
1283 | clocksource_select_fallback(); | |
1284 | if (curr_clocksource == cs) | |
1285 | return -EBUSY; | |
1286 | } | |
2aae7bcf | 1287 | |
39232ed5 BW |
1288 | if (clocksource_is_suspend(cs)) { |
1289 | /* | |
1290 | * Select and try to install a replacement suspend clocksource. | |
1291 | * If no replacement suspend clocksource, we will just let the | |
1292 | * clocksource go and have no suspend clocksource. | |
1293 | */ | |
1294 | clocksource_suspend_select(true); | |
1295 | } | |
1296 | ||
2aae7bcf | 1297 | clocksource_watchdog_lock(&flags); |
7eaeb343 TG |
1298 | clocksource_dequeue_watchdog(cs); |
1299 | list_del_init(&cs->list); | |
2aae7bcf PZ |
1300 | clocksource_watchdog_unlock(&flags); |
1301 | ||
7eaeb343 TG |
1302 | return 0; |
1303 | } | |
1304 | ||
4713e22c TG |
1305 | /** |
1306 | * clocksource_unregister - remove a registered clocksource | |
b1b73d09 | 1307 | * @cs: clocksource to be unregistered |
4713e22c | 1308 | */ |
a89c7edb | 1309 | int clocksource_unregister(struct clocksource *cs) |
4713e22c | 1310 | { |
a89c7edb TG |
1311 | int ret = 0; |
1312 | ||
75c5158f | 1313 | mutex_lock(&clocksource_mutex); |
a89c7edb TG |
1314 | if (!list_empty(&cs->list)) |
1315 | ret = clocksource_unbind(cs); | |
75c5158f | 1316 | mutex_unlock(&clocksource_mutex); |
a89c7edb | 1317 | return ret; |
4713e22c | 1318 | } |
fb63a0eb | 1319 | EXPORT_SYMBOL(clocksource_unregister); |
4713e22c | 1320 | |
2b013700 | 1321 | #ifdef CONFIG_SYSFS |
734efb46 | 1322 | /** |
e87821d1 | 1323 | * current_clocksource_show - sysfs interface for current clocksource |
734efb46 | 1324 | * @dev: unused |
b1b73d09 | 1325 | * @attr: unused |
734efb46 | 1326 | * @buf: char buffer to be filled with clocksource list |
1327 | * | |
1328 | * Provides sysfs interface for listing current clocksource. | |
1329 | */ | |
e87821d1 BW |
1330 | static ssize_t current_clocksource_show(struct device *dev, |
1331 | struct device_attribute *attr, | |
1332 | char *buf) | |
734efb46 | 1333 | { |
5e2cb101 | 1334 | ssize_t count = 0; |
734efb46 | 1335 | |
75c5158f | 1336 | mutex_lock(&clocksource_mutex); |
8f0acb7f | 1337 | count = sysfs_emit(buf, "%s\n", curr_clocksource->name); |
75c5158f | 1338 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1339 | |
5e2cb101 | 1340 | return count; |
734efb46 | 1341 | } |
1342 | ||
891292a7 | 1343 | ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt) |
29b54078 TG |
1344 | { |
1345 | size_t ret = cnt; | |
1346 | ||
1347 | /* strings from sysfs write are not 0 terminated! */ | |
1348 | if (!cnt || cnt >= CS_NAME_LEN) | |
1349 | return -EINVAL; | |
1350 | ||
1351 | /* strip of \n: */ | |
1352 | if (buf[cnt-1] == '\n') | |
1353 | cnt--; | |
1354 | if (cnt > 0) | |
1355 | memcpy(dst, buf, cnt); | |
1356 | dst[cnt] = 0; | |
1357 | return ret; | |
1358 | } | |
1359 | ||
734efb46 | 1360 | /** |
e87821d1 | 1361 | * current_clocksource_store - interface for manually overriding clocksource |
734efb46 | 1362 | * @dev: unused |
b1b73d09 | 1363 | * @attr: unused |
734efb46 | 1364 | * @buf: name of override clocksource |
1365 | * @count: length of buffer | |
1366 | * | |
1367 | * Takes input from sysfs interface for manually overriding the default | |
b71a8eb0 | 1368 | * clocksource selection. |
734efb46 | 1369 | */ |
e87821d1 BW |
1370 | static ssize_t current_clocksource_store(struct device *dev, |
1371 | struct device_attribute *attr, | |
1372 | const char *buf, size_t count) | |
734efb46 | 1373 | { |
233bcb41 | 1374 | ssize_t ret; |
734efb46 | 1375 | |
75c5158f | 1376 | mutex_lock(&clocksource_mutex); |
734efb46 | 1377 | |
03e13cf5 | 1378 | ret = sysfs_get_uname(buf, override_name, count); |
29b54078 TG |
1379 | if (ret >= 0) |
1380 | clocksource_select(); | |
734efb46 | 1381 | |
75c5158f | 1382 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1383 | |
1384 | return ret; | |
1385 | } | |
e87821d1 | 1386 | static DEVICE_ATTR_RW(current_clocksource); |
734efb46 | 1387 | |
7eaeb343 | 1388 | /** |
e87821d1 | 1389 | * unbind_clocksource_store - interface for manually unbinding clocksource |
7eaeb343 TG |
1390 | * @dev: unused |
1391 | * @attr: unused | |
1392 | * @buf: unused | |
1393 | * @count: length of buffer | |
1394 | * | |
1395 | * Takes input from sysfs interface for manually unbinding a clocksource. | |
1396 | */ | |
e87821d1 | 1397 | static ssize_t unbind_clocksource_store(struct device *dev, |
7eaeb343 TG |
1398 | struct device_attribute *attr, |
1399 | const char *buf, size_t count) | |
1400 | { | |
1401 | struct clocksource *cs; | |
1402 | char name[CS_NAME_LEN]; | |
233bcb41 | 1403 | ssize_t ret; |
7eaeb343 | 1404 | |
03e13cf5 | 1405 | ret = sysfs_get_uname(buf, name, count); |
7eaeb343 TG |
1406 | if (ret < 0) |
1407 | return ret; | |
1408 | ||
1409 | ret = -ENODEV; | |
1410 | mutex_lock(&clocksource_mutex); | |
1411 | list_for_each_entry(cs, &clocksource_list, list) { | |
1412 | if (strcmp(cs->name, name)) | |
1413 | continue; | |
1414 | ret = clocksource_unbind(cs); | |
1415 | break; | |
1416 | } | |
1417 | mutex_unlock(&clocksource_mutex); | |
1418 | ||
1419 | return ret ? ret : count; | |
1420 | } | |
e87821d1 | 1421 | static DEVICE_ATTR_WO(unbind_clocksource); |
7eaeb343 | 1422 | |
734efb46 | 1423 | /** |
e87821d1 | 1424 | * available_clocksource_show - sysfs interface for listing clocksource |
734efb46 | 1425 | * @dev: unused |
b1b73d09 | 1426 | * @attr: unused |
734efb46 | 1427 | * @buf: char buffer to be filled with clocksource list |
1428 | * | |
1429 | * Provides sysfs interface for listing registered clocksources | |
1430 | */ | |
e87821d1 BW |
1431 | static ssize_t available_clocksource_show(struct device *dev, |
1432 | struct device_attribute *attr, | |
1433 | char *buf) | |
734efb46 | 1434 | { |
2e197586 | 1435 | struct clocksource *src; |
5e2cb101 | 1436 | ssize_t count = 0; |
734efb46 | 1437 | |
75c5158f | 1438 | mutex_lock(&clocksource_mutex); |
2e197586 | 1439 | list_for_each_entry(src, &clocksource_list, list) { |
cd6d95d8 TG |
1440 | /* |
1441 | * Don't show non-HRES clocksource if the tick code is | |
1442 | * in one shot mode (highres=on or nohz=on) | |
1443 | */ | |
1444 | if (!tick_oneshot_mode_active() || | |
1445 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) | |
3f68535a | 1446 | count += snprintf(buf + count, |
5e2cb101 MX |
1447 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), |
1448 | "%s ", src->name); | |
734efb46 | 1449 | } |
75c5158f | 1450 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1451 | |
5e2cb101 MX |
1452 | count += snprintf(buf + count, |
1453 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); | |
734efb46 | 1454 | |
5e2cb101 | 1455 | return count; |
734efb46 | 1456 | } |
e87821d1 | 1457 | static DEVICE_ATTR_RO(available_clocksource); |
734efb46 | 1458 | |
27263e8d BW |
1459 | static struct attribute *clocksource_attrs[] = { |
1460 | &dev_attr_current_clocksource.attr, | |
1461 | &dev_attr_unbind_clocksource.attr, | |
1462 | &dev_attr_available_clocksource.attr, | |
1463 | NULL | |
1464 | }; | |
1465 | ATTRIBUTE_GROUPS(clocksource); | |
1466 | ||
2bc7fc24 | 1467 | static const struct bus_type clocksource_subsys = { |
af5ca3f4 | 1468 | .name = "clocksource", |
d369a5d8 | 1469 | .dev_name = "clocksource", |
734efb46 | 1470 | }; |
1471 | ||
d369a5d8 | 1472 | static struct device device_clocksource = { |
734efb46 | 1473 | .id = 0, |
d369a5d8 | 1474 | .bus = &clocksource_subsys, |
27263e8d | 1475 | .groups = clocksource_groups, |
734efb46 | 1476 | }; |
1477 | ||
ad596171 | 1478 | static int __init init_clocksource_sysfs(void) |
734efb46 | 1479 | { |
d369a5d8 | 1480 | int error = subsys_system_register(&clocksource_subsys, NULL); |
734efb46 | 1481 | |
1482 | if (!error) | |
d369a5d8 | 1483 | error = device_register(&device_clocksource); |
27263e8d | 1484 | |
734efb46 | 1485 | return error; |
1486 | } | |
1487 | ||
1488 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 1489 | #endif /* CONFIG_SYSFS */ |
734efb46 | 1490 | |
1491 | /** | |
1492 | * boot_override_clocksource - boot clock override | |
1493 | * @str: override name | |
1494 | * | |
1495 | * Takes a clocksource= boot argument and uses it | |
1496 | * as the clocksource override name. | |
1497 | */ | |
1498 | static int __init boot_override_clocksource(char* str) | |
1499 | { | |
75c5158f | 1500 | mutex_lock(&clocksource_mutex); |
734efb46 | 1501 | if (str) |
76edc27e | 1502 | strscpy(override_name, str, sizeof(override_name)); |
75c5158f | 1503 | mutex_unlock(&clocksource_mutex); |
734efb46 | 1504 | return 1; |
1505 | } | |
1506 | ||
1507 | __setup("clocksource=", boot_override_clocksource); | |
1508 | ||
1509 | /** | |
1510 | * boot_override_clock - Compatibility layer for deprecated boot option | |
1511 | * @str: override name | |
1512 | * | |
1513 | * DEPRECATED! Takes a clock= boot argument and uses it | |
1514 | * as the clocksource override name | |
1515 | */ | |
1516 | static int __init boot_override_clock(char* str) | |
1517 | { | |
5d0cf410 | 1518 | if (!strcmp(str, "pmtmr")) { |
45bbfe64 | 1519 | pr_warn("clock=pmtmr is deprecated - use clocksource=acpi_pm\n"); |
5d0cf410 | 1520 | return boot_override_clocksource("acpi_pm"); |
1521 | } | |
45bbfe64 | 1522 | pr_warn("clock= boot option is deprecated - use clocksource=xyz\n"); |
734efb46 | 1523 | return boot_override_clocksource(str); |
1524 | } | |
1525 | ||
1526 | __setup("clock=", boot_override_clock); |