Commit | Line | Data |
---|---|---|
734efb46 | 1 | /* |
2 | * linux/kernel/time/clocksource.c | |
3 | * | |
4 | * This file contains the functions which manage clocksource drivers. | |
5 | * | |
6 | * Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2 of the License, or | |
11 | * (at your option) any later version. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program; if not, write to the Free Software | |
20 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
21 | * | |
22 | * TODO WishList: | |
23 | * o Allow clocksource drivers to be unregistered | |
24 | * o get rid of clocksource_jiffies extern | |
25 | */ | |
26 | ||
27 | #include <linux/clocksource.h> | |
28 | #include <linux/sysdev.h> | |
29 | #include <linux/init.h> | |
30 | #include <linux/module.h> | |
dc29a365 | 31 | #include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */ |
79bf2bb3 | 32 | #include <linux/tick.h> |
734efb46 | 33 | |
34 | /* XXX - Would like a better way for initializing curr_clocksource */ | |
35 | extern struct clocksource clocksource_jiffies; | |
36 | ||
37 | /*[Clocksource internal variables]--------- | |
38 | * curr_clocksource: | |
39 | * currently selected clocksource. Initialized to clocksource_jiffies. | |
40 | * next_clocksource: | |
41 | * pending next selected clocksource. | |
42 | * clocksource_list: | |
43 | * linked list with the registered clocksources | |
44 | * clocksource_lock: | |
45 | * protects manipulations to curr_clocksource and next_clocksource | |
46 | * and the clocksource_list | |
47 | * override_name: | |
48 | * Name of the user-specified clocksource. | |
49 | */ | |
50 | static struct clocksource *curr_clocksource = &clocksource_jiffies; | |
51 | static struct clocksource *next_clocksource; | |
92c7e002 | 52 | static struct clocksource *clocksource_override; |
734efb46 | 53 | static LIST_HEAD(clocksource_list); |
54 | static DEFINE_SPINLOCK(clocksource_lock); | |
55 | static char override_name[32]; | |
56 | static int finished_booting; | |
57 | ||
6bb74df4 | 58 | /* clocksource_done_booting - Called near the end of core bootup |
734efb46 | 59 | * |
6bb74df4 | 60 | * Hack to avoid lots of clocksource churn at boot time. |
61 | * We use fs_initcall because we want this to start before | |
62 | * device_initcall but after subsys_initcall. | |
734efb46 | 63 | */ |
ad596171 | 64 | static int __init clocksource_done_booting(void) |
734efb46 | 65 | { |
66 | finished_booting = 1; | |
67 | return 0; | |
68 | } | |
6bb74df4 | 69 | fs_initcall(clocksource_done_booting); |
734efb46 | 70 | |
5d8b34fd TG |
71 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
72 | static LIST_HEAD(watchdog_list); | |
73 | static struct clocksource *watchdog; | |
74 | static struct timer_list watchdog_timer; | |
75 | static DEFINE_SPINLOCK(watchdog_lock); | |
76 | static cycle_t watchdog_last; | |
8f89441b | 77 | static unsigned long watchdog_resumed; |
b52f52a0 | 78 | |
5d8b34fd | 79 | /* |
35c35d1a | 80 | * Interval: 0.5sec Threshold: 0.0625s |
5d8b34fd TG |
81 | */ |
82 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
35c35d1a | 83 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) |
5d8b34fd TG |
84 | |
85 | static void clocksource_ratewd(struct clocksource *cs, int64_t delta) | |
86 | { | |
35c35d1a | 87 | if (delta > -WATCHDOG_THRESHOLD && delta < WATCHDOG_THRESHOLD) |
5d8b34fd TG |
88 | return; |
89 | ||
90 | printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n", | |
91 | cs->name, delta); | |
92 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); | |
93 | clocksource_change_rating(cs, 0); | |
94 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
95 | list_del(&cs->wd_list); | |
96 | } | |
97 | ||
98 | static void clocksource_watchdog(unsigned long data) | |
99 | { | |
100 | struct clocksource *cs, *tmp; | |
101 | cycle_t csnow, wdnow; | |
102 | int64_t wd_nsec, cs_nsec; | |
b52f52a0 | 103 | int resumed; |
5d8b34fd TG |
104 | |
105 | spin_lock(&watchdog_lock); | |
106 | ||
8f89441b | 107 | resumed = test_and_clear_bit(0, &watchdog_resumed); |
b52f52a0 | 108 | |
5d8b34fd TG |
109 | wdnow = watchdog->read(); |
110 | wd_nsec = cyc2ns(watchdog, (wdnow - watchdog_last) & watchdog->mask); | |
111 | watchdog_last = wdnow; | |
112 | ||
113 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { | |
114 | csnow = cs->read(); | |
b52f52a0 TG |
115 | |
116 | if (unlikely(resumed)) { | |
117 | cs->wd_last = csnow; | |
118 | continue; | |
119 | } | |
120 | ||
5d8b34fd TG |
121 | /* Initialized ? */ |
122 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG)) { | |
123 | if ((cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
124 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
125 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
79bf2bb3 TG |
126 | /* |
127 | * We just marked the clocksource as | |
128 | * highres-capable, notify the rest of the | |
129 | * system as well so that we transition | |
130 | * into high-res mode: | |
131 | */ | |
132 | tick_clock_notify(); | |
5d8b34fd TG |
133 | } |
134 | cs->flags |= CLOCK_SOURCE_WATCHDOG; | |
135 | cs->wd_last = csnow; | |
136 | } else { | |
137 | cs_nsec = cyc2ns(cs, (csnow - cs->wd_last) & cs->mask); | |
138 | cs->wd_last = csnow; | |
139 | /* Check the delta. Might remove from the list ! */ | |
140 | clocksource_ratewd(cs, cs_nsec - wd_nsec); | |
141 | } | |
142 | } | |
143 | ||
144 | if (!list_empty(&watchdog_list)) { | |
1ada5cba AK |
145 | /* Cycle through CPUs to check if the CPUs stay synchronized to |
146 | * each other. */ | |
147 | int next_cpu = next_cpu(raw_smp_processor_id(), cpu_online_map); | |
148 | if (next_cpu >= NR_CPUS) | |
149 | next_cpu = first_cpu(cpu_online_map); | |
150 | watchdog_timer.expires += WATCHDOG_INTERVAL; | |
151 | add_timer_on(&watchdog_timer, next_cpu); | |
5d8b34fd TG |
152 | } |
153 | spin_unlock(&watchdog_lock); | |
154 | } | |
b52f52a0 TG |
155 | static void clocksource_resume_watchdog(void) |
156 | { | |
8f89441b | 157 | set_bit(0, &watchdog_resumed); |
b52f52a0 TG |
158 | } |
159 | ||
5d8b34fd TG |
160 | static void clocksource_check_watchdog(struct clocksource *cs) |
161 | { | |
162 | struct clocksource *cse; | |
163 | unsigned long flags; | |
164 | ||
165 | spin_lock_irqsave(&watchdog_lock, flags); | |
166 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
167 | int started = !list_empty(&watchdog_list); | |
168 | ||
169 | list_add(&cs->wd_list, &watchdog_list); | |
170 | if (!started && watchdog) { | |
171 | watchdog_last = watchdog->read(); | |
172 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; | |
1ada5cba | 173 | add_timer_on(&watchdog_timer, first_cpu(cpu_online_map)); |
5d8b34fd | 174 | } |
948ac6d7 TG |
175 | } else { |
176 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
5d8b34fd TG |
177 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
178 | ||
179 | if (!watchdog || cs->rating > watchdog->rating) { | |
180 | if (watchdog) | |
181 | del_timer(&watchdog_timer); | |
182 | watchdog = cs; | |
1077f5a9 | 183 | init_timer_deferrable(&watchdog_timer); |
5d8b34fd TG |
184 | watchdog_timer.function = clocksource_watchdog; |
185 | ||
186 | /* Reset watchdog cycles */ | |
187 | list_for_each_entry(cse, &watchdog_list, wd_list) | |
188 | cse->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
189 | /* Start if list is not empty */ | |
190 | if (!list_empty(&watchdog_list)) { | |
191 | watchdog_last = watchdog->read(); | |
192 | watchdog_timer.expires = | |
193 | jiffies + WATCHDOG_INTERVAL; | |
1ada5cba AK |
194 | add_timer_on(&watchdog_timer, |
195 | first_cpu(cpu_online_map)); | |
5d8b34fd TG |
196 | } |
197 | } | |
198 | } | |
199 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
200 | } | |
201 | #else | |
202 | static void clocksource_check_watchdog(struct clocksource *cs) | |
203 | { | |
204 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
205 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
206 | } | |
b52f52a0 TG |
207 | |
208 | static inline void clocksource_resume_watchdog(void) { } | |
5d8b34fd TG |
209 | #endif |
210 | ||
b52f52a0 TG |
211 | /** |
212 | * clocksource_resume - resume the clocksource(s) | |
213 | */ | |
214 | void clocksource_resume(void) | |
215 | { | |
2e197586 | 216 | struct clocksource *cs; |
b52f52a0 TG |
217 | unsigned long flags; |
218 | ||
219 | spin_lock_irqsave(&clocksource_lock, flags); | |
220 | ||
2e197586 | 221 | list_for_each_entry(cs, &clocksource_list, list) { |
b52f52a0 TG |
222 | if (cs->resume) |
223 | cs->resume(); | |
224 | } | |
225 | ||
226 | clocksource_resume_watchdog(); | |
227 | ||
228 | spin_unlock_irqrestore(&clocksource_lock, flags); | |
229 | } | |
230 | ||
734efb46 | 231 | /** |
a2752549 | 232 | * clocksource_get_next - Returns the selected clocksource |
734efb46 | 233 | * |
234 | */ | |
a2752549 | 235 | struct clocksource *clocksource_get_next(void) |
734efb46 | 236 | { |
237 | unsigned long flags; | |
238 | ||
239 | spin_lock_irqsave(&clocksource_lock, flags); | |
240 | if (next_clocksource && finished_booting) { | |
241 | curr_clocksource = next_clocksource; | |
242 | next_clocksource = NULL; | |
243 | } | |
244 | spin_unlock_irqrestore(&clocksource_lock, flags); | |
245 | ||
246 | return curr_clocksource; | |
247 | } | |
248 | ||
249 | /** | |
92c7e002 | 250 | * select_clocksource - Selects the best registered clocksource. |
734efb46 | 251 | * |
252 | * Private function. Must hold clocksource_lock when called. | |
253 | * | |
92c7e002 TG |
254 | * Select the clocksource with the best rating, or the clocksource, |
255 | * which is selected by userspace override. | |
734efb46 | 256 | */ |
257 | static struct clocksource *select_clocksource(void) | |
258 | { | |
5d8b34fd TG |
259 | struct clocksource *next; |
260 | ||
92c7e002 TG |
261 | if (list_empty(&clocksource_list)) |
262 | return NULL; | |
734efb46 | 263 | |
92c7e002 | 264 | if (clocksource_override) |
5d8b34fd TG |
265 | next = clocksource_override; |
266 | else | |
267 | next = list_entry(clocksource_list.next, struct clocksource, | |
268 | list); | |
734efb46 | 269 | |
5d8b34fd TG |
270 | if (next == curr_clocksource) |
271 | return NULL; | |
272 | ||
273 | return next; | |
734efb46 | 274 | } |
275 | ||
92c7e002 TG |
276 | /* |
277 | * Enqueue the clocksource sorted by rating | |
734efb46 | 278 | */ |
92c7e002 | 279 | static int clocksource_enqueue(struct clocksource *c) |
734efb46 | 280 | { |
92c7e002 | 281 | struct list_head *tmp, *entry = &clocksource_list; |
734efb46 | 282 | |
283 | list_for_each(tmp, &clocksource_list) { | |
92c7e002 TG |
284 | struct clocksource *cs; |
285 | ||
286 | cs = list_entry(tmp, struct clocksource, list); | |
287 | if (cs == c) | |
288 | return -EBUSY; | |
289 | /* Keep track of the place, where to insert */ | |
290 | if (cs->rating >= c->rating) | |
291 | entry = tmp; | |
734efb46 | 292 | } |
92c7e002 TG |
293 | list_add(&c->list, entry); |
294 | ||
295 | if (strlen(c->name) == strlen(override_name) && | |
296 | !strcmp(c->name, override_name)) | |
297 | clocksource_override = c; | |
734efb46 | 298 | |
299 | return 0; | |
300 | } | |
301 | ||
302 | /** | |
a2752549 | 303 | * clocksource_register - Used to install new clocksources |
734efb46 | 304 | * @t: clocksource to be registered |
305 | * | |
306 | * Returns -EBUSY if registration fails, zero otherwise. | |
307 | */ | |
a2752549 | 308 | int clocksource_register(struct clocksource *c) |
734efb46 | 309 | { |
734efb46 | 310 | unsigned long flags; |
5d8b34fd | 311 | int ret; |
734efb46 | 312 | |
313 | spin_lock_irqsave(&clocksource_lock, flags); | |
92c7e002 TG |
314 | ret = clocksource_enqueue(c); |
315 | if (!ret) | |
734efb46 | 316 | next_clocksource = select_clocksource(); |
734efb46 | 317 | spin_unlock_irqrestore(&clocksource_lock, flags); |
5d8b34fd TG |
318 | if (!ret) |
319 | clocksource_check_watchdog(c); | |
734efb46 | 320 | return ret; |
321 | } | |
a2752549 | 322 | EXPORT_SYMBOL(clocksource_register); |
734efb46 | 323 | |
324 | /** | |
92c7e002 | 325 | * clocksource_change_rating - Change the rating of a registered clocksource |
734efb46 | 326 | * |
734efb46 | 327 | */ |
92c7e002 | 328 | void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb46 | 329 | { |
330 | unsigned long flags; | |
331 | ||
332 | spin_lock_irqsave(&clocksource_lock, flags); | |
92c7e002 | 333 | list_del(&cs->list); |
5d8b34fd | 334 | cs->rating = rating; |
92c7e002 | 335 | clocksource_enqueue(cs); |
734efb46 | 336 | next_clocksource = select_clocksource(); |
337 | spin_unlock_irqrestore(&clocksource_lock, flags); | |
338 | } | |
339 | ||
2b013700 | 340 | #ifdef CONFIG_SYSFS |
734efb46 | 341 | /** |
342 | * sysfs_show_current_clocksources - sysfs interface for current clocksource | |
343 | * @dev: unused | |
344 | * @buf: char buffer to be filled with clocksource list | |
345 | * | |
346 | * Provides sysfs interface for listing current clocksource. | |
347 | */ | |
348 | static ssize_t | |
349 | sysfs_show_current_clocksources(struct sys_device *dev, char *buf) | |
350 | { | |
351 | char *curr = buf; | |
352 | ||
353 | spin_lock_irq(&clocksource_lock); | |
354 | curr += sprintf(curr, "%s ", curr_clocksource->name); | |
355 | spin_unlock_irq(&clocksource_lock); | |
356 | ||
357 | curr += sprintf(curr, "\n"); | |
358 | ||
359 | return curr - buf; | |
360 | } | |
361 | ||
362 | /** | |
363 | * sysfs_override_clocksource - interface for manually overriding clocksource | |
364 | * @dev: unused | |
365 | * @buf: name of override clocksource | |
366 | * @count: length of buffer | |
367 | * | |
368 | * Takes input from sysfs interface for manually overriding the default | |
369 | * clocksource selction. | |
370 | */ | |
371 | static ssize_t sysfs_override_clocksource(struct sys_device *dev, | |
372 | const char *buf, size_t count) | |
373 | { | |
92c7e002 | 374 | struct clocksource *ovr = NULL; |
734efb46 | 375 | size_t ret = count; |
92c7e002 TG |
376 | int len; |
377 | ||
734efb46 | 378 | /* strings from sysfs write are not 0 terminated! */ |
379 | if (count >= sizeof(override_name)) | |
380 | return -EINVAL; | |
381 | ||
382 | /* strip of \n: */ | |
383 | if (buf[count-1] == '\n') | |
384 | count--; | |
734efb46 | 385 | |
386 | spin_lock_irq(&clocksource_lock); | |
387 | ||
92c7e002 TG |
388 | if (count > 0) |
389 | memcpy(override_name, buf, count); | |
734efb46 | 390 | override_name[count] = 0; |
391 | ||
92c7e002 TG |
392 | len = strlen(override_name); |
393 | if (len) { | |
2e197586 MK |
394 | struct clocksource *cs; |
395 | ||
92c7e002 TG |
396 | ovr = clocksource_override; |
397 | /* try to select it: */ | |
2e197586 | 398 | list_for_each_entry(cs, &clocksource_list, list) { |
92c7e002 TG |
399 | if (strlen(cs->name) == len && |
400 | !strcmp(cs->name, override_name)) | |
401 | ovr = cs; | |
402 | } | |
403 | } | |
404 | ||
405 | /* Reselect, when the override name has changed */ | |
406 | if (ovr != clocksource_override) { | |
407 | clocksource_override = ovr; | |
408 | next_clocksource = select_clocksource(); | |
409 | } | |
734efb46 | 410 | |
411 | spin_unlock_irq(&clocksource_lock); | |
412 | ||
413 | return ret; | |
414 | } | |
415 | ||
416 | /** | |
417 | * sysfs_show_available_clocksources - sysfs interface for listing clocksource | |
418 | * @dev: unused | |
419 | * @buf: char buffer to be filled with clocksource list | |
420 | * | |
421 | * Provides sysfs interface for listing registered clocksources | |
422 | */ | |
423 | static ssize_t | |
424 | sysfs_show_available_clocksources(struct sys_device *dev, char *buf) | |
425 | { | |
2e197586 | 426 | struct clocksource *src; |
734efb46 | 427 | char *curr = buf; |
428 | ||
429 | spin_lock_irq(&clocksource_lock); | |
2e197586 | 430 | list_for_each_entry(src, &clocksource_list, list) { |
734efb46 | 431 | curr += sprintf(curr, "%s ", src->name); |
432 | } | |
433 | spin_unlock_irq(&clocksource_lock); | |
434 | ||
435 | curr += sprintf(curr, "\n"); | |
436 | ||
437 | return curr - buf; | |
438 | } | |
439 | ||
440 | /* | |
441 | * Sysfs setup bits: | |
442 | */ | |
443 | static SYSDEV_ATTR(current_clocksource, 0600, sysfs_show_current_clocksources, | |
f5f1a24a | 444 | sysfs_override_clocksource); |
734efb46 | 445 | |
446 | static SYSDEV_ATTR(available_clocksource, 0600, | |
f5f1a24a | 447 | sysfs_show_available_clocksources, NULL); |
734efb46 | 448 | |
449 | static struct sysdev_class clocksource_sysclass = { | |
af5ca3f4 | 450 | .name = "clocksource", |
734efb46 | 451 | }; |
452 | ||
453 | static struct sys_device device_clocksource = { | |
454 | .id = 0, | |
455 | .cls = &clocksource_sysclass, | |
456 | }; | |
457 | ||
ad596171 | 458 | static int __init init_clocksource_sysfs(void) |
734efb46 | 459 | { |
460 | int error = sysdev_class_register(&clocksource_sysclass); | |
461 | ||
462 | if (!error) | |
463 | error = sysdev_register(&device_clocksource); | |
464 | if (!error) | |
465 | error = sysdev_create_file( | |
466 | &device_clocksource, | |
467 | &attr_current_clocksource); | |
468 | if (!error) | |
469 | error = sysdev_create_file( | |
470 | &device_clocksource, | |
471 | &attr_available_clocksource); | |
472 | return error; | |
473 | } | |
474 | ||
475 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 476 | #endif /* CONFIG_SYSFS */ |
734efb46 | 477 | |
478 | /** | |
479 | * boot_override_clocksource - boot clock override | |
480 | * @str: override name | |
481 | * | |
482 | * Takes a clocksource= boot argument and uses it | |
483 | * as the clocksource override name. | |
484 | */ | |
485 | static int __init boot_override_clocksource(char* str) | |
486 | { | |
487 | unsigned long flags; | |
488 | spin_lock_irqsave(&clocksource_lock, flags); | |
489 | if (str) | |
490 | strlcpy(override_name, str, sizeof(override_name)); | |
491 | spin_unlock_irqrestore(&clocksource_lock, flags); | |
492 | return 1; | |
493 | } | |
494 | ||
495 | __setup("clocksource=", boot_override_clocksource); | |
496 | ||
497 | /** | |
498 | * boot_override_clock - Compatibility layer for deprecated boot option | |
499 | * @str: override name | |
500 | * | |
501 | * DEPRECATED! Takes a clock= boot argument and uses it | |
502 | * as the clocksource override name | |
503 | */ | |
504 | static int __init boot_override_clock(char* str) | |
505 | { | |
5d0cf410 | 506 | if (!strcmp(str, "pmtmr")) { |
507 | printk("Warning: clock=pmtmr is deprecated. " | |
508 | "Use clocksource=acpi_pm.\n"); | |
509 | return boot_override_clocksource("acpi_pm"); | |
510 | } | |
511 | printk("Warning! clock= boot option is deprecated. " | |
512 | "Use clocksource=xyz\n"); | |
734efb46 | 513 | return boot_override_clocksource(str); |
514 | } | |
515 | ||
516 | __setup("clock=", boot_override_clock); |