[PATCH] net: Kill some unneeded allocation return value casts in libertas
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / kernel / time / clocksource.c
blob51b6a6a6158cab016aa11b09f0a65c1919c750ec
1 /*
2 * linux/kernel/time/clocksource.c
4 * This file contains the functions which manage clocksource drivers.
6 * Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com)
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.
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.
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.
22 * TODO WishList:
23 * o Allow clocksource drivers to be unregistered
24 * o get rid of clocksource_jiffies extern
27 #include <linux/clocksource.h>
28 #include <linux/sysdev.h>
29 #include <linux/init.h>
30 #include <linux/module.h>
31 #include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */
32 #include <linux/tick.h>
34 /* XXX - Would like a better way for initializing curr_clocksource */
35 extern struct clocksource clocksource_jiffies;
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.
50 static struct clocksource *curr_clocksource = &clocksource_jiffies;
51 static struct clocksource *next_clocksource;
52 static struct clocksource *clocksource_override;
53 static LIST_HEAD(clocksource_list);
54 static DEFINE_SPINLOCK(clocksource_lock);
55 static char override_name[32];
56 static int finished_booting;
58 /* clocksource_done_booting - Called near the end of core bootup
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.
64 static int __init clocksource_done_booting(void)
66 finished_booting = 1;
67 return 0;
69 fs_initcall(clocksource_done_booting);
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 static unsigned long watchdog_resumed;
80 * Interval: 0.5sec Threshold: 0.0625s
82 #define WATCHDOG_INTERVAL (HZ >> 1)
83 #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4)
85 static void clocksource_ratewd(struct clocksource *cs, int64_t delta)
87 if (delta > -WATCHDOG_THRESHOLD && delta < WATCHDOG_THRESHOLD)
88 return;
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);
98 static void clocksource_watchdog(unsigned long data)
100 struct clocksource *cs, *tmp;
101 cycle_t csnow, wdnow;
102 int64_t wd_nsec, cs_nsec;
103 int resumed;
105 spin_lock(&watchdog_lock);
107 resumed = test_and_clear_bit(0, &watchdog_resumed);
109 wdnow = watchdog->read();
110 wd_nsec = cyc2ns(watchdog, (wdnow - watchdog_last) & watchdog->mask);
111 watchdog_last = wdnow;
113 list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) {
114 csnow = cs->read();
116 if (unlikely(resumed)) {
117 cs->wd_last = csnow;
118 continue;
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;
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:
132 tick_clock_notify();
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);
144 if (!list_empty(&watchdog_list)) {
145 __mod_timer(&watchdog_timer,
146 watchdog_timer.expires + WATCHDOG_INTERVAL);
148 spin_unlock(&watchdog_lock);
150 static void clocksource_resume_watchdog(void)
152 set_bit(0, &watchdog_resumed);
155 static void clocksource_check_watchdog(struct clocksource *cs)
157 struct clocksource *cse;
158 unsigned long flags;
160 spin_lock_irqsave(&watchdog_lock, flags);
161 if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) {
162 int started = !list_empty(&watchdog_list);
164 list_add(&cs->wd_list, &watchdog_list);
165 if (!started && watchdog) {
166 watchdog_last = watchdog->read();
167 watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL;
168 add_timer(&watchdog_timer);
170 } else {
171 if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)
172 cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
174 if (!watchdog || cs->rating > watchdog->rating) {
175 if (watchdog)
176 del_timer(&watchdog_timer);
177 watchdog = cs;
178 init_timer(&watchdog_timer);
179 watchdog_timer.function = clocksource_watchdog;
181 /* Reset watchdog cycles */
182 list_for_each_entry(cse, &watchdog_list, wd_list)
183 cse->flags &= ~CLOCK_SOURCE_WATCHDOG;
184 /* Start if list is not empty */
185 if (!list_empty(&watchdog_list)) {
186 watchdog_last = watchdog->read();
187 watchdog_timer.expires =
188 jiffies + WATCHDOG_INTERVAL;
189 add_timer(&watchdog_timer);
193 spin_unlock_irqrestore(&watchdog_lock, flags);
195 #else
196 static void clocksource_check_watchdog(struct clocksource *cs)
198 if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)
199 cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
202 static inline void clocksource_resume_watchdog(void) { }
203 #endif
206 * clocksource_resume - resume the clocksource(s)
208 void clocksource_resume(void)
210 struct list_head *tmp;
211 unsigned long flags;
213 spin_lock_irqsave(&clocksource_lock, flags);
215 list_for_each(tmp, &clocksource_list) {
216 struct clocksource *cs;
218 cs = list_entry(tmp, struct clocksource, list);
219 if (cs->resume)
220 cs->resume();
223 clocksource_resume_watchdog();
225 spin_unlock_irqrestore(&clocksource_lock, flags);
229 * clocksource_get_next - Returns the selected clocksource
232 struct clocksource *clocksource_get_next(void)
234 unsigned long flags;
236 spin_lock_irqsave(&clocksource_lock, flags);
237 if (next_clocksource && finished_booting) {
238 curr_clocksource = next_clocksource;
239 next_clocksource = NULL;
241 spin_unlock_irqrestore(&clocksource_lock, flags);
243 return curr_clocksource;
247 * select_clocksource - Selects the best registered clocksource.
249 * Private function. Must hold clocksource_lock when called.
251 * Select the clocksource with the best rating, or the clocksource,
252 * which is selected by userspace override.
254 static struct clocksource *select_clocksource(void)
256 struct clocksource *next;
258 if (list_empty(&clocksource_list))
259 return NULL;
261 if (clocksource_override)
262 next = clocksource_override;
263 else
264 next = list_entry(clocksource_list.next, struct clocksource,
265 list);
267 if (next == curr_clocksource)
268 return NULL;
270 return next;
274 * Enqueue the clocksource sorted by rating
276 static int clocksource_enqueue(struct clocksource *c)
278 struct list_head *tmp, *entry = &clocksource_list;
280 list_for_each(tmp, &clocksource_list) {
281 struct clocksource *cs;
283 cs = list_entry(tmp, struct clocksource, list);
284 if (cs == c)
285 return -EBUSY;
286 /* Keep track of the place, where to insert */
287 if (cs->rating >= c->rating)
288 entry = tmp;
290 list_add(&c->list, entry);
292 if (strlen(c->name) == strlen(override_name) &&
293 !strcmp(c->name, override_name))
294 clocksource_override = c;
296 return 0;
300 * clocksource_register - Used to install new clocksources
301 * @t: clocksource to be registered
303 * Returns -EBUSY if registration fails, zero otherwise.
305 int clocksource_register(struct clocksource *c)
307 unsigned long flags;
308 int ret;
310 spin_lock_irqsave(&clocksource_lock, flags);
311 ret = clocksource_enqueue(c);
312 if (!ret)
313 next_clocksource = select_clocksource();
314 spin_unlock_irqrestore(&clocksource_lock, flags);
315 if (!ret)
316 clocksource_check_watchdog(c);
317 return ret;
319 EXPORT_SYMBOL(clocksource_register);
322 * clocksource_change_rating - Change the rating of a registered clocksource
325 void clocksource_change_rating(struct clocksource *cs, int rating)
327 unsigned long flags;
329 spin_lock_irqsave(&clocksource_lock, flags);
330 list_del(&cs->list);
331 cs->rating = rating;
332 clocksource_enqueue(cs);
333 next_clocksource = select_clocksource();
334 spin_unlock_irqrestore(&clocksource_lock, flags);
337 #ifdef CONFIG_SYSFS
339 * sysfs_show_current_clocksources - sysfs interface for current clocksource
340 * @dev: unused
341 * @buf: char buffer to be filled with clocksource list
343 * Provides sysfs interface for listing current clocksource.
345 static ssize_t
346 sysfs_show_current_clocksources(struct sys_device *dev, char *buf)
348 char *curr = buf;
350 spin_lock_irq(&clocksource_lock);
351 curr += sprintf(curr, "%s ", curr_clocksource->name);
352 spin_unlock_irq(&clocksource_lock);
354 curr += sprintf(curr, "\n");
356 return curr - buf;
360 * sysfs_override_clocksource - interface for manually overriding clocksource
361 * @dev: unused
362 * @buf: name of override clocksource
363 * @count: length of buffer
365 * Takes input from sysfs interface for manually overriding the default
366 * clocksource selction.
368 static ssize_t sysfs_override_clocksource(struct sys_device *dev,
369 const char *buf, size_t count)
371 struct clocksource *ovr = NULL;
372 struct list_head *tmp;
373 size_t ret = count;
374 int len;
376 /* strings from sysfs write are not 0 terminated! */
377 if (count >= sizeof(override_name))
378 return -EINVAL;
380 /* strip of \n: */
381 if (buf[count-1] == '\n')
382 count--;
384 spin_lock_irq(&clocksource_lock);
386 if (count > 0)
387 memcpy(override_name, buf, count);
388 override_name[count] = 0;
390 len = strlen(override_name);
391 if (len) {
392 ovr = clocksource_override;
393 /* try to select it: */
394 list_for_each(tmp, &clocksource_list) {
395 struct clocksource *cs;
397 cs = list_entry(tmp, struct clocksource, list);
398 if (strlen(cs->name) == len &&
399 !strcmp(cs->name, override_name))
400 ovr = cs;
404 /* Reselect, when the override name has changed */
405 if (ovr != clocksource_override) {
406 clocksource_override = ovr;
407 next_clocksource = select_clocksource();
410 spin_unlock_irq(&clocksource_lock);
412 return ret;
416 * sysfs_show_available_clocksources - sysfs interface for listing clocksource
417 * @dev: unused
418 * @buf: char buffer to be filled with clocksource list
420 * Provides sysfs interface for listing registered clocksources
422 static ssize_t
423 sysfs_show_available_clocksources(struct sys_device *dev, char *buf)
425 struct list_head *tmp;
426 char *curr = buf;
428 spin_lock_irq(&clocksource_lock);
429 list_for_each(tmp, &clocksource_list) {
430 struct clocksource *src;
432 src = list_entry(tmp, struct clocksource, list);
433 curr += sprintf(curr, "%s ", src->name);
435 spin_unlock_irq(&clocksource_lock);
437 curr += sprintf(curr, "\n");
439 return curr - buf;
443 * Sysfs setup bits:
445 static SYSDEV_ATTR(current_clocksource, 0600, sysfs_show_current_clocksources,
446 sysfs_override_clocksource);
448 static SYSDEV_ATTR(available_clocksource, 0600,
449 sysfs_show_available_clocksources, NULL);
451 static struct sysdev_class clocksource_sysclass = {
452 set_kset_name("clocksource"),
455 static struct sys_device device_clocksource = {
456 .id = 0,
457 .cls = &clocksource_sysclass,
460 static int __init init_clocksource_sysfs(void)
462 int error = sysdev_class_register(&clocksource_sysclass);
464 if (!error)
465 error = sysdev_register(&device_clocksource);
466 if (!error)
467 error = sysdev_create_file(
468 &device_clocksource,
469 &attr_current_clocksource);
470 if (!error)
471 error = sysdev_create_file(
472 &device_clocksource,
473 &attr_available_clocksource);
474 return error;
477 device_initcall(init_clocksource_sysfs);
478 #endif /* CONFIG_SYSFS */
481 * boot_override_clocksource - boot clock override
482 * @str: override name
484 * Takes a clocksource= boot argument and uses it
485 * as the clocksource override name.
487 static int __init boot_override_clocksource(char* str)
489 unsigned long flags;
490 spin_lock_irqsave(&clocksource_lock, flags);
491 if (str)
492 strlcpy(override_name, str, sizeof(override_name));
493 spin_unlock_irqrestore(&clocksource_lock, flags);
494 return 1;
497 __setup("clocksource=", boot_override_clocksource);
500 * boot_override_clock - Compatibility layer for deprecated boot option
501 * @str: override name
503 * DEPRECATED! Takes a clock= boot argument and uses it
504 * as the clocksource override name
506 static int __init boot_override_clock(char* str)
508 if (!strcmp(str, "pmtmr")) {
509 printk("Warning: clock=pmtmr is deprecated. "
510 "Use clocksource=acpi_pm.\n");
511 return boot_override_clocksource("acpi_pm");
513 printk("Warning! clock= boot option is deprecated. "
514 "Use clocksource=xyz\n");
515 return boot_override_clocksource(str);
518 __setup("clock=", boot_override_clock);