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1 | /* |
2 | * linux/kernel/time/clockevents.c | |
3 | * | |
4 | * This file contains functions which manage clock event devices. | |
5 | * | |
6 | * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de> | |
7 | * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar | |
8 | * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner | |
9 | * | |
10 | * This code is licenced under the GPL version 2. For details see | |
11 | * kernel-base/COPYING. | |
12 | */ | |
13 | ||
14 | #include <linux/clockchips.h> | |
15 | #include <linux/hrtimer.h> | |
16 | #include <linux/init.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/notifier.h> | |
19 | #include <linux/smp.h> | |
20 | #include <linux/sysdev.h> | |
21 | ||
22 | /* The registered clock event devices */ | |
23 | static LIST_HEAD(clockevent_devices); | |
24 | static LIST_HEAD(clockevents_released); | |
25 | ||
26 | /* Notification for clock events */ | |
27 | static RAW_NOTIFIER_HEAD(clockevents_chain); | |
28 | ||
29 | /* Protection for the above */ | |
30 | static DEFINE_SPINLOCK(clockevents_lock); | |
31 | ||
32 | /** | |
33 | * clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds | |
34 | * @latch: value to convert | |
35 | * @evt: pointer to clock event device descriptor | |
36 | * | |
37 | * Math helper, returns latch value converted to nanoseconds (bound checked) | |
38 | */ | |
39 | unsigned long clockevent_delta2ns(unsigned long latch, | |
40 | struct clock_event_device *evt) | |
41 | { | |
42 | u64 clc = ((u64) latch << evt->shift); | |
43 | ||
44 | do_div(clc, evt->mult); | |
45 | if (clc < 1000) | |
46 | clc = 1000; | |
47 | if (clc > LONG_MAX) | |
48 | clc = LONG_MAX; | |
49 | ||
50 | return (unsigned long) clc; | |
51 | } | |
52 | ||
53 | /** | |
54 | * clockevents_set_mode - set the operating mode of a clock event device | |
55 | * @dev: device to modify | |
56 | * @mode: new mode | |
57 | * | |
58 | * Must be called with interrupts disabled ! | |
59 | */ | |
60 | void clockevents_set_mode(struct clock_event_device *dev, | |
61 | enum clock_event_mode mode) | |
62 | { | |
63 | if (dev->mode != mode) { | |
64 | dev->set_mode(mode, dev); | |
65 | dev->mode = mode; | |
66 | } | |
67 | } | |
68 | ||
69 | /** | |
70 | * clockevents_program_event - Reprogram the clock event device. | |
71 | * @expires: absolute expiry time (monotonic clock) | |
72 | * | |
73 | * Returns 0 on success, -ETIME when the event is in the past. | |
74 | */ | |
75 | int clockevents_program_event(struct clock_event_device *dev, ktime_t expires, | |
76 | ktime_t now) | |
77 | { | |
78 | unsigned long long clc; | |
79 | int64_t delta; | |
80 | ||
81 | delta = ktime_to_ns(ktime_sub(expires, now)); | |
82 | ||
83 | if (delta <= 0) | |
84 | return -ETIME; | |
85 | ||
86 | dev->next_event = expires; | |
87 | ||
88 | if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN) | |
89 | return 0; | |
90 | ||
91 | if (delta > dev->max_delta_ns) | |
92 | delta = dev->max_delta_ns; | |
93 | if (delta < dev->min_delta_ns) | |
94 | delta = dev->min_delta_ns; | |
95 | ||
96 | clc = delta * dev->mult; | |
97 | clc >>= dev->shift; | |
98 | ||
99 | return dev->set_next_event((unsigned long) clc, dev); | |
100 | } | |
101 | ||
102 | /** | |
103 | * clockevents_register_notifier - register a clock events change listener | |
104 | */ | |
105 | int clockevents_register_notifier(struct notifier_block *nb) | |
106 | { | |
107 | int ret; | |
108 | ||
109 | spin_lock(&clockevents_lock); | |
110 | ret = raw_notifier_chain_register(&clockevents_chain, nb); | |
111 | spin_unlock(&clockevents_lock); | |
112 | ||
113 | return ret; | |
114 | } | |
115 | ||
116 | /** | |
117 | * clockevents_unregister_notifier - unregister a clock events change listener | |
118 | */ | |
119 | void clockevents_unregister_notifier(struct notifier_block *nb) | |
120 | { | |
121 | spin_lock(&clockevents_lock); | |
122 | raw_notifier_chain_unregister(&clockevents_chain, nb); | |
123 | spin_unlock(&clockevents_lock); | |
124 | } | |
125 | ||
126 | /* | |
127 | * Notify about a clock event change. Called with clockevents_lock | |
128 | * held. | |
129 | */ | |
130 | static void clockevents_do_notify(unsigned long reason, void *dev) | |
131 | { | |
132 | raw_notifier_call_chain(&clockevents_chain, reason, dev); | |
133 | } | |
134 | ||
135 | /* | |
136 | * Called after a notify add to make devices availble which were | |
137 | * released from the notifier call. | |
138 | */ | |
139 | static void clockevents_notify_released(void) | |
140 | { | |
141 | struct clock_event_device *dev; | |
142 | ||
143 | while (!list_empty(&clockevents_released)) { | |
144 | dev = list_entry(clockevents_released.next, | |
145 | struct clock_event_device, list); | |
146 | list_del(&dev->list); | |
147 | list_add(&dev->list, &clockevent_devices); | |
148 | clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); | |
149 | } | |
150 | } | |
151 | ||
152 | /** | |
153 | * clockevents_register_device - register a clock event device | |
154 | * @dev: device to register | |
155 | */ | |
156 | void clockevents_register_device(struct clock_event_device *dev) | |
157 | { | |
158 | BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED); | |
159 | ||
160 | spin_lock(&clockevents_lock); | |
161 | ||
162 | list_add(&dev->list, &clockevent_devices); | |
163 | clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); | |
164 | clockevents_notify_released(); | |
165 | ||
166 | spin_unlock(&clockevents_lock); | |
167 | } | |
168 | ||
169 | /* | |
170 | * Noop handler when we shut down an event device | |
171 | */ | |
172 | static void clockevents_handle_noop(struct clock_event_device *dev) | |
173 | { | |
174 | } | |
175 | ||
176 | /** | |
177 | * clockevents_exchange_device - release and request clock devices | |
178 | * @old: device to release (can be NULL) | |
179 | * @new: device to request (can be NULL) | |
180 | * | |
181 | * Called from the notifier chain. clockevents_lock is held already | |
182 | */ | |
183 | void clockevents_exchange_device(struct clock_event_device *old, | |
184 | struct clock_event_device *new) | |
185 | { | |
186 | unsigned long flags; | |
187 | ||
188 | local_irq_save(flags); | |
189 | /* | |
190 | * Caller releases a clock event device. We queue it into the | |
191 | * released list and do a notify add later. | |
192 | */ | |
193 | if (old) { | |
194 | old->event_handler = clockevents_handle_noop; | |
195 | clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED); | |
196 | list_del(&old->list); | |
197 | list_add(&old->list, &clockevents_released); | |
198 | } | |
199 | ||
200 | if (new) { | |
201 | BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED); | |
202 | clockevents_set_mode(new, CLOCK_EVT_MODE_SHUTDOWN); | |
203 | } | |
204 | local_irq_restore(flags); | |
205 | } | |
206 | ||
207 | /** | |
208 | * clockevents_request_device | |
209 | */ | |
210 | struct clock_event_device *clockevents_request_device(unsigned int features, | |
211 | cpumask_t cpumask) | |
212 | { | |
213 | struct clock_event_device *cur, *dev = NULL; | |
214 | struct list_head *tmp; | |
215 | ||
216 | spin_lock(&clockevents_lock); | |
217 | ||
218 | list_for_each(tmp, &clockevent_devices) { | |
219 | cur = list_entry(tmp, struct clock_event_device, list); | |
220 | ||
221 | if ((cur->features & features) == features && | |
222 | cpus_equal(cpumask, cur->cpumask)) { | |
223 | if (!dev || dev->rating < cur->rating) | |
224 | dev = cur; | |
225 | } | |
226 | } | |
227 | ||
228 | clockevents_exchange_device(NULL, dev); | |
229 | ||
230 | spin_unlock(&clockevents_lock); | |
231 | ||
232 | return dev; | |
233 | } | |
234 | ||
235 | /** | |
236 | * clockevents_release_device | |
237 | */ | |
238 | void clockevents_release_device(struct clock_event_device *dev) | |
239 | { | |
240 | spin_lock(&clockevents_lock); | |
241 | ||
242 | clockevents_exchange_device(dev, NULL); | |
243 | clockevents_notify_released(); | |
244 | ||
245 | spin_unlock(&clockevents_lock); | |
246 | } | |
247 | ||
248 | /** | |
249 | * clockevents_notify - notification about relevant events | |
250 | */ | |
251 | void clockevents_notify(unsigned long reason, void *arg) | |
252 | { | |
253 | spin_lock(&clockevents_lock); | |
254 | clockevents_do_notify(reason, arg); | |
255 | ||
256 | switch (reason) { | |
257 | case CLOCK_EVT_NOTIFY_CPU_DEAD: | |
258 | /* | |
259 | * Unregister the clock event devices which were | |
260 | * released from the users in the notify chain. | |
261 | */ | |
262 | while (!list_empty(&clockevents_released)) { | |
263 | struct clock_event_device *dev; | |
264 | ||
265 | dev = list_entry(clockevents_released.next, | |
266 | struct clock_event_device, list); | |
267 | list_del(&dev->list); | |
268 | } | |
269 | break; | |
270 | default: | |
271 | break; | |
272 | } | |
273 | spin_unlock(&clockevents_lock); | |
274 | } | |
275 | EXPORT_SYMBOL_GPL(clockevents_notify); | |
276 | ||
277 | #ifdef CONFIG_SYSFS | |
278 | ||
279 | /** | |
280 | * clockevents_show_registered - sysfs interface for listing clockevents | |
281 | * @dev: unused | |
282 | * @buf: char buffer to be filled with clock events list | |
283 | * | |
284 | * Provides sysfs interface for listing registered clock event devices | |
285 | */ | |
286 | static ssize_t clockevents_show_registered(struct sys_device *dev, char *buf) | |
287 | { | |
288 | struct list_head *tmp; | |
289 | char *p = buf; | |
290 | int cpu; | |
291 | ||
292 | spin_lock(&clockevents_lock); | |
293 | ||
294 | list_for_each(tmp, &clockevent_devices) { | |
295 | struct clock_event_device *ce; | |
296 | ||
297 | ce = list_entry(tmp, struct clock_event_device, list); | |
298 | p += sprintf(p, "%-20s F:%04x M:%d", ce->name, | |
299 | ce->features, ce->mode); | |
300 | p += sprintf(p, " C:"); | |
301 | if (!cpus_equal(ce->cpumask, cpu_possible_map)) { | |
302 | for_each_cpu_mask(cpu, ce->cpumask) | |
303 | p += sprintf(p, " %d", cpu); | |
304 | } else { | |
305 | /* | |
306 | * FIXME: Add the cpu which is handling this sucker | |
307 | */ | |
308 | } | |
309 | p += sprintf(p, "\n"); | |
310 | } | |
311 | ||
312 | spin_unlock(&clockevents_lock); | |
313 | ||
314 | return p - buf; | |
315 | } | |
316 | ||
317 | /* | |
318 | * Sysfs setup bits: | |
319 | */ | |
320 | static SYSDEV_ATTR(registered, 0600, | |
321 | clockevents_show_registered, NULL); | |
322 | ||
323 | static struct sysdev_class clockevents_sysclass = { | |
324 | set_kset_name("clockevents"), | |
325 | }; | |
326 | ||
327 | static struct sys_device clockevents_sys_device = { | |
328 | .id = 0, | |
329 | .cls = &clockevents_sysclass, | |
330 | }; | |
331 | ||
332 | static int __init clockevents_sysfs_init(void) | |
333 | { | |
334 | int error = sysdev_class_register(&clockevents_sysclass); | |
335 | ||
336 | if (!error) | |
337 | error = sysdev_register(&clockevents_sys_device); | |
338 | if (!error) | |
339 | error = sysdev_create_file( | |
340 | &clockevents_sys_device, | |
341 | &attr_registered); | |
342 | return error; | |
343 | } | |
344 | device_initcall(clockevents_sysfs_init); | |
345 | #endif |