Commit | Line | Data |
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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; | |
77 | /* | |
78 | * Interval: 0.5sec Treshold: 0.0625s | |
79 | */ | |
80 | #define WATCHDOG_INTERVAL (HZ >> 1) | |
81 | #define WATCHDOG_TRESHOLD (NSEC_PER_SEC >> 4) | |
82 | ||
83 | static void clocksource_ratewd(struct clocksource *cs, int64_t delta) | |
84 | { | |
85 | if (delta > -WATCHDOG_TRESHOLD && delta < WATCHDOG_TRESHOLD) | |
86 | return; | |
87 | ||
88 | printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n", | |
89 | cs->name, delta); | |
90 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); | |
91 | clocksource_change_rating(cs, 0); | |
92 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
93 | list_del(&cs->wd_list); | |
94 | } | |
95 | ||
96 | static void clocksource_watchdog(unsigned long data) | |
97 | { | |
98 | struct clocksource *cs, *tmp; | |
99 | cycle_t csnow, wdnow; | |
100 | int64_t wd_nsec, cs_nsec; | |
101 | ||
102 | spin_lock(&watchdog_lock); | |
103 | ||
104 | wdnow = watchdog->read(); | |
105 | wd_nsec = cyc2ns(watchdog, (wdnow - watchdog_last) & watchdog->mask); | |
106 | watchdog_last = wdnow; | |
107 | ||
108 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { | |
109 | csnow = cs->read(); | |
110 | /* Initialized ? */ | |
111 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG)) { | |
112 | if ((cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && | |
113 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { | |
114 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
79bf2bb3 TG |
115 | /* |
116 | * We just marked the clocksource as | |
117 | * highres-capable, notify the rest of the | |
118 | * system as well so that we transition | |
119 | * into high-res mode: | |
120 | */ | |
121 | tick_clock_notify(); | |
5d8b34fd TG |
122 | } |
123 | cs->flags |= CLOCK_SOURCE_WATCHDOG; | |
124 | cs->wd_last = csnow; | |
125 | } else { | |
126 | cs_nsec = cyc2ns(cs, (csnow - cs->wd_last) & cs->mask); | |
127 | cs->wd_last = csnow; | |
128 | /* Check the delta. Might remove from the list ! */ | |
129 | clocksource_ratewd(cs, cs_nsec - wd_nsec); | |
130 | } | |
131 | } | |
132 | ||
133 | if (!list_empty(&watchdog_list)) { | |
134 | __mod_timer(&watchdog_timer, | |
135 | watchdog_timer.expires + WATCHDOG_INTERVAL); | |
136 | } | |
137 | spin_unlock(&watchdog_lock); | |
138 | } | |
139 | static void clocksource_check_watchdog(struct clocksource *cs) | |
140 | { | |
141 | struct clocksource *cse; | |
142 | unsigned long flags; | |
143 | ||
144 | spin_lock_irqsave(&watchdog_lock, flags); | |
145 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { | |
146 | int started = !list_empty(&watchdog_list); | |
147 | ||
148 | list_add(&cs->wd_list, &watchdog_list); | |
149 | if (!started && watchdog) { | |
150 | watchdog_last = watchdog->read(); | |
151 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; | |
152 | add_timer(&watchdog_timer); | |
153 | } | |
948ac6d7 TG |
154 | } else { |
155 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
5d8b34fd TG |
156 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
157 | ||
158 | if (!watchdog || cs->rating > watchdog->rating) { | |
159 | if (watchdog) | |
160 | del_timer(&watchdog_timer); | |
161 | watchdog = cs; | |
162 | init_timer(&watchdog_timer); | |
163 | watchdog_timer.function = clocksource_watchdog; | |
164 | ||
165 | /* Reset watchdog cycles */ | |
166 | list_for_each_entry(cse, &watchdog_list, wd_list) | |
167 | cse->flags &= ~CLOCK_SOURCE_WATCHDOG; | |
168 | /* Start if list is not empty */ | |
169 | if (!list_empty(&watchdog_list)) { | |
170 | watchdog_last = watchdog->read(); | |
171 | watchdog_timer.expires = | |
172 | jiffies + WATCHDOG_INTERVAL; | |
173 | add_timer(&watchdog_timer); | |
174 | } | |
175 | } | |
176 | } | |
177 | spin_unlock_irqrestore(&watchdog_lock, flags); | |
178 | } | |
179 | #else | |
180 | static void clocksource_check_watchdog(struct clocksource *cs) | |
181 | { | |
182 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) | |
183 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; | |
184 | } | |
185 | #endif | |
186 | ||
734efb46 | 187 | /** |
a2752549 | 188 | * clocksource_get_next - Returns the selected clocksource |
734efb46 | 189 | * |
190 | */ | |
a2752549 | 191 | struct clocksource *clocksource_get_next(void) |
734efb46 | 192 | { |
193 | unsigned long flags; | |
194 | ||
195 | spin_lock_irqsave(&clocksource_lock, flags); | |
196 | if (next_clocksource && finished_booting) { | |
197 | curr_clocksource = next_clocksource; | |
198 | next_clocksource = NULL; | |
199 | } | |
200 | spin_unlock_irqrestore(&clocksource_lock, flags); | |
201 | ||
202 | return curr_clocksource; | |
203 | } | |
204 | ||
205 | /** | |
92c7e002 | 206 | * select_clocksource - Selects the best registered clocksource. |
734efb46 | 207 | * |
208 | * Private function. Must hold clocksource_lock when called. | |
209 | * | |
92c7e002 TG |
210 | * Select the clocksource with the best rating, or the clocksource, |
211 | * which is selected by userspace override. | |
734efb46 | 212 | */ |
213 | static struct clocksource *select_clocksource(void) | |
214 | { | |
5d8b34fd TG |
215 | struct clocksource *next; |
216 | ||
92c7e002 TG |
217 | if (list_empty(&clocksource_list)) |
218 | return NULL; | |
734efb46 | 219 | |
92c7e002 | 220 | if (clocksource_override) |
5d8b34fd TG |
221 | next = clocksource_override; |
222 | else | |
223 | next = list_entry(clocksource_list.next, struct clocksource, | |
224 | list); | |
734efb46 | 225 | |
5d8b34fd TG |
226 | if (next == curr_clocksource) |
227 | return NULL; | |
228 | ||
229 | return next; | |
734efb46 | 230 | } |
231 | ||
92c7e002 TG |
232 | /* |
233 | * Enqueue the clocksource sorted by rating | |
734efb46 | 234 | */ |
92c7e002 | 235 | static int clocksource_enqueue(struct clocksource *c) |
734efb46 | 236 | { |
92c7e002 | 237 | struct list_head *tmp, *entry = &clocksource_list; |
734efb46 | 238 | |
239 | list_for_each(tmp, &clocksource_list) { | |
92c7e002 TG |
240 | struct clocksource *cs; |
241 | ||
242 | cs = list_entry(tmp, struct clocksource, list); | |
243 | if (cs == c) | |
244 | return -EBUSY; | |
245 | /* Keep track of the place, where to insert */ | |
246 | if (cs->rating >= c->rating) | |
247 | entry = tmp; | |
734efb46 | 248 | } |
92c7e002 TG |
249 | list_add(&c->list, entry); |
250 | ||
251 | if (strlen(c->name) == strlen(override_name) && | |
252 | !strcmp(c->name, override_name)) | |
253 | clocksource_override = c; | |
734efb46 | 254 | |
255 | return 0; | |
256 | } | |
257 | ||
258 | /** | |
a2752549 | 259 | * clocksource_register - Used to install new clocksources |
734efb46 | 260 | * @t: clocksource to be registered |
261 | * | |
262 | * Returns -EBUSY if registration fails, zero otherwise. | |
263 | */ | |
a2752549 | 264 | int clocksource_register(struct clocksource *c) |
734efb46 | 265 | { |
734efb46 | 266 | unsigned long flags; |
5d8b34fd | 267 | int ret; |
734efb46 | 268 | |
269 | spin_lock_irqsave(&clocksource_lock, flags); | |
92c7e002 TG |
270 | ret = clocksource_enqueue(c); |
271 | if (!ret) | |
734efb46 | 272 | next_clocksource = select_clocksource(); |
734efb46 | 273 | spin_unlock_irqrestore(&clocksource_lock, flags); |
5d8b34fd TG |
274 | if (!ret) |
275 | clocksource_check_watchdog(c); | |
734efb46 | 276 | return ret; |
277 | } | |
a2752549 | 278 | EXPORT_SYMBOL(clocksource_register); |
734efb46 | 279 | |
280 | /** | |
92c7e002 | 281 | * clocksource_change_rating - Change the rating of a registered clocksource |
734efb46 | 282 | * |
734efb46 | 283 | */ |
92c7e002 | 284 | void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb46 | 285 | { |
286 | unsigned long flags; | |
287 | ||
288 | spin_lock_irqsave(&clocksource_lock, flags); | |
92c7e002 | 289 | list_del(&cs->list); |
5d8b34fd | 290 | cs->rating = rating; |
92c7e002 | 291 | clocksource_enqueue(cs); |
734efb46 | 292 | next_clocksource = select_clocksource(); |
293 | spin_unlock_irqrestore(&clocksource_lock, flags); | |
294 | } | |
295 | ||
2b013700 | 296 | #ifdef CONFIG_SYSFS |
734efb46 | 297 | /** |
298 | * sysfs_show_current_clocksources - sysfs interface for current clocksource | |
299 | * @dev: unused | |
300 | * @buf: char buffer to be filled with clocksource list | |
301 | * | |
302 | * Provides sysfs interface for listing current clocksource. | |
303 | */ | |
304 | static ssize_t | |
305 | sysfs_show_current_clocksources(struct sys_device *dev, char *buf) | |
306 | { | |
307 | char *curr = buf; | |
308 | ||
309 | spin_lock_irq(&clocksource_lock); | |
310 | curr += sprintf(curr, "%s ", curr_clocksource->name); | |
311 | spin_unlock_irq(&clocksource_lock); | |
312 | ||
313 | curr += sprintf(curr, "\n"); | |
314 | ||
315 | return curr - buf; | |
316 | } | |
317 | ||
318 | /** | |
319 | * sysfs_override_clocksource - interface for manually overriding clocksource | |
320 | * @dev: unused | |
321 | * @buf: name of override clocksource | |
322 | * @count: length of buffer | |
323 | * | |
324 | * Takes input from sysfs interface for manually overriding the default | |
325 | * clocksource selction. | |
326 | */ | |
327 | static ssize_t sysfs_override_clocksource(struct sys_device *dev, | |
328 | const char *buf, size_t count) | |
329 | { | |
92c7e002 TG |
330 | struct clocksource *ovr = NULL; |
331 | struct list_head *tmp; | |
734efb46 | 332 | size_t ret = count; |
92c7e002 TG |
333 | int len; |
334 | ||
734efb46 | 335 | /* strings from sysfs write are not 0 terminated! */ |
336 | if (count >= sizeof(override_name)) | |
337 | return -EINVAL; | |
338 | ||
339 | /* strip of \n: */ | |
340 | if (buf[count-1] == '\n') | |
341 | count--; | |
734efb46 | 342 | |
343 | spin_lock_irq(&clocksource_lock); | |
344 | ||
92c7e002 TG |
345 | if (count > 0) |
346 | memcpy(override_name, buf, count); | |
734efb46 | 347 | override_name[count] = 0; |
348 | ||
92c7e002 TG |
349 | len = strlen(override_name); |
350 | if (len) { | |
351 | ovr = clocksource_override; | |
352 | /* try to select it: */ | |
353 | list_for_each(tmp, &clocksource_list) { | |
354 | struct clocksource *cs; | |
355 | ||
356 | cs = list_entry(tmp, struct clocksource, list); | |
357 | if (strlen(cs->name) == len && | |
358 | !strcmp(cs->name, override_name)) | |
359 | ovr = cs; | |
360 | } | |
361 | } | |
362 | ||
363 | /* Reselect, when the override name has changed */ | |
364 | if (ovr != clocksource_override) { | |
365 | clocksource_override = ovr; | |
366 | next_clocksource = select_clocksource(); | |
367 | } | |
734efb46 | 368 | |
369 | spin_unlock_irq(&clocksource_lock); | |
370 | ||
371 | return ret; | |
372 | } | |
373 | ||
374 | /** | |
375 | * sysfs_show_available_clocksources - sysfs interface for listing clocksource | |
376 | * @dev: unused | |
377 | * @buf: char buffer to be filled with clocksource list | |
378 | * | |
379 | * Provides sysfs interface for listing registered clocksources | |
380 | */ | |
381 | static ssize_t | |
382 | sysfs_show_available_clocksources(struct sys_device *dev, char *buf) | |
383 | { | |
384 | struct list_head *tmp; | |
385 | char *curr = buf; | |
386 | ||
387 | spin_lock_irq(&clocksource_lock); | |
388 | list_for_each(tmp, &clocksource_list) { | |
389 | struct clocksource *src; | |
390 | ||
391 | src = list_entry(tmp, struct clocksource, list); | |
392 | curr += sprintf(curr, "%s ", src->name); | |
393 | } | |
394 | spin_unlock_irq(&clocksource_lock); | |
395 | ||
396 | curr += sprintf(curr, "\n"); | |
397 | ||
398 | return curr - buf; | |
399 | } | |
400 | ||
401 | /* | |
402 | * Sysfs setup bits: | |
403 | */ | |
404 | static SYSDEV_ATTR(current_clocksource, 0600, sysfs_show_current_clocksources, | |
f5f1a24a | 405 | sysfs_override_clocksource); |
734efb46 | 406 | |
407 | static SYSDEV_ATTR(available_clocksource, 0600, | |
f5f1a24a | 408 | sysfs_show_available_clocksources, NULL); |
734efb46 | 409 | |
410 | static struct sysdev_class clocksource_sysclass = { | |
411 | set_kset_name("clocksource"), | |
412 | }; | |
413 | ||
414 | static struct sys_device device_clocksource = { | |
415 | .id = 0, | |
416 | .cls = &clocksource_sysclass, | |
417 | }; | |
418 | ||
ad596171 | 419 | static int __init init_clocksource_sysfs(void) |
734efb46 | 420 | { |
421 | int error = sysdev_class_register(&clocksource_sysclass); | |
422 | ||
423 | if (!error) | |
424 | error = sysdev_register(&device_clocksource); | |
425 | if (!error) | |
426 | error = sysdev_create_file( | |
427 | &device_clocksource, | |
428 | &attr_current_clocksource); | |
429 | if (!error) | |
430 | error = sysdev_create_file( | |
431 | &device_clocksource, | |
432 | &attr_available_clocksource); | |
433 | return error; | |
434 | } | |
435 | ||
436 | device_initcall(init_clocksource_sysfs); | |
2b013700 | 437 | #endif /* CONFIG_SYSFS */ |
734efb46 | 438 | |
439 | /** | |
440 | * boot_override_clocksource - boot clock override | |
441 | * @str: override name | |
442 | * | |
443 | * Takes a clocksource= boot argument and uses it | |
444 | * as the clocksource override name. | |
445 | */ | |
446 | static int __init boot_override_clocksource(char* str) | |
447 | { | |
448 | unsigned long flags; | |
449 | spin_lock_irqsave(&clocksource_lock, flags); | |
450 | if (str) | |
451 | strlcpy(override_name, str, sizeof(override_name)); | |
452 | spin_unlock_irqrestore(&clocksource_lock, flags); | |
453 | return 1; | |
454 | } | |
455 | ||
456 | __setup("clocksource=", boot_override_clocksource); | |
457 | ||
458 | /** | |
459 | * boot_override_clock - Compatibility layer for deprecated boot option | |
460 | * @str: override name | |
461 | * | |
462 | * DEPRECATED! Takes a clock= boot argument and uses it | |
463 | * as the clocksource override name | |
464 | */ | |
465 | static int __init boot_override_clock(char* str) | |
466 | { | |
5d0cf410 | 467 | if (!strcmp(str, "pmtmr")) { |
468 | printk("Warning: clock=pmtmr is deprecated. " | |
469 | "Use clocksource=acpi_pm.\n"); | |
470 | return boot_override_clocksource("acpi_pm"); | |
471 | } | |
472 | printk("Warning! clock= boot option is deprecated. " | |
473 | "Use clocksource=xyz\n"); | |
734efb46 | 474 | return boot_override_clocksource(str); |
475 | } | |
476 | ||
477 | __setup("clock=", boot_override_clock); |