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d316c57f TG |
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> | |
d316c57f | 20 | |
8e1a928a HS |
21 | #include "tick-internal.h" |
22 | ||
d316c57f TG |
23 | /* The registered clock event devices */ |
24 | static LIST_HEAD(clockevent_devices); | |
25 | static LIST_HEAD(clockevents_released); | |
26 | ||
27 | /* Notification for clock events */ | |
28 | static RAW_NOTIFIER_HEAD(clockevents_chain); | |
29 | ||
30 | /* Protection for the above */ | |
b5f91da0 | 31 | static DEFINE_RAW_SPINLOCK(clockevents_lock); |
d316c57f TG |
32 | |
33 | /** | |
34 | * clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds | |
35 | * @latch: value to convert | |
36 | * @evt: pointer to clock event device descriptor | |
37 | * | |
38 | * Math helper, returns latch value converted to nanoseconds (bound checked) | |
39 | */ | |
97813f2f | 40 | u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt) |
d316c57f | 41 | { |
97813f2f | 42 | u64 clc = (u64) latch << evt->shift; |
d316c57f | 43 | |
45fe4fe1 IM |
44 | if (unlikely(!evt->mult)) { |
45 | evt->mult = 1; | |
46 | WARN_ON(1); | |
47 | } | |
48 | ||
d316c57f TG |
49 | do_div(clc, evt->mult); |
50 | if (clc < 1000) | |
51 | clc = 1000; | |
97813f2f JH |
52 | if (clc > KTIME_MAX) |
53 | clc = KTIME_MAX; | |
d316c57f | 54 | |
97813f2f | 55 | return clc; |
d316c57f | 56 | } |
c81fc2c3 | 57 | EXPORT_SYMBOL_GPL(clockevent_delta2ns); |
d316c57f TG |
58 | |
59 | /** | |
60 | * clockevents_set_mode - set the operating mode of a clock event device | |
61 | * @dev: device to modify | |
62 | * @mode: new mode | |
63 | * | |
64 | * Must be called with interrupts disabled ! | |
65 | */ | |
66 | void clockevents_set_mode(struct clock_event_device *dev, | |
67 | enum clock_event_mode mode) | |
68 | { | |
69 | if (dev->mode != mode) { | |
70 | dev->set_mode(mode, dev); | |
71 | dev->mode = mode; | |
2d68259d MD |
72 | |
73 | /* | |
74 | * A nsec2cyc multiplicator of 0 is invalid and we'd crash | |
75 | * on it, so fix it up and emit a warning: | |
76 | */ | |
77 | if (mode == CLOCK_EVT_MODE_ONESHOT) { | |
78 | if (unlikely(!dev->mult)) { | |
79 | dev->mult = 1; | |
80 | WARN_ON(1); | |
81 | } | |
82 | } | |
d316c57f TG |
83 | } |
84 | } | |
85 | ||
2344abbc TG |
86 | /** |
87 | * clockevents_shutdown - shutdown the device and clear next_event | |
88 | * @dev: device to shutdown | |
89 | */ | |
90 | void clockevents_shutdown(struct clock_event_device *dev) | |
91 | { | |
92 | clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); | |
93 | dev->next_event.tv64 = KTIME_MAX; | |
94 | } | |
95 | ||
d1748302 MS |
96 | #ifdef CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST |
97 | ||
98 | /* Limit min_delta to a jiffie */ | |
99 | #define MIN_DELTA_LIMIT (NSEC_PER_SEC / HZ) | |
100 | ||
101 | /** | |
102 | * clockevents_increase_min_delta - raise minimum delta of a clock event device | |
103 | * @dev: device to increase the minimum delta | |
104 | * | |
105 | * Returns 0 on success, -ETIME when the minimum delta reached the limit. | |
106 | */ | |
107 | static int clockevents_increase_min_delta(struct clock_event_device *dev) | |
108 | { | |
109 | /* Nothing to do if we already reached the limit */ | |
110 | if (dev->min_delta_ns >= MIN_DELTA_LIMIT) { | |
111 | printk(KERN_WARNING "CE: Reprogramming failure. Giving up\n"); | |
112 | dev->next_event.tv64 = KTIME_MAX; | |
113 | return -ETIME; | |
114 | } | |
115 | ||
116 | if (dev->min_delta_ns < 5000) | |
117 | dev->min_delta_ns = 5000; | |
118 | else | |
119 | dev->min_delta_ns += dev->min_delta_ns >> 1; | |
120 | ||
121 | if (dev->min_delta_ns > MIN_DELTA_LIMIT) | |
122 | dev->min_delta_ns = MIN_DELTA_LIMIT; | |
123 | ||
124 | printk(KERN_WARNING "CE: %s increased min_delta_ns to %llu nsec\n", | |
125 | dev->name ? dev->name : "?", | |
126 | (unsigned long long) dev->min_delta_ns); | |
127 | return 0; | |
128 | } | |
129 | ||
130 | /** | |
131 | * clockevents_program_min_delta - Set clock event device to the minimum delay. | |
132 | * @dev: device to program | |
133 | * | |
134 | * Returns 0 on success, -ETIME when the retry loop failed. | |
135 | */ | |
136 | static int clockevents_program_min_delta(struct clock_event_device *dev) | |
137 | { | |
138 | unsigned long long clc; | |
139 | int64_t delta; | |
140 | int i; | |
141 | ||
142 | for (i = 0;;) { | |
143 | delta = dev->min_delta_ns; | |
144 | dev->next_event = ktime_add_ns(ktime_get(), delta); | |
145 | ||
146 | if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN) | |
147 | return 0; | |
148 | ||
149 | dev->retries++; | |
150 | clc = ((unsigned long long) delta * dev->mult) >> dev->shift; | |
151 | if (dev->set_next_event((unsigned long) clc, dev) == 0) | |
152 | return 0; | |
153 | ||
154 | if (++i > 2) { | |
155 | /* | |
156 | * We tried 3 times to program the device with the | |
157 | * given min_delta_ns. Try to increase the minimum | |
158 | * delta, if that fails as well get out of here. | |
159 | */ | |
160 | if (clockevents_increase_min_delta(dev)) | |
161 | return -ETIME; | |
162 | i = 0; | |
163 | } | |
164 | } | |
165 | } | |
166 | ||
167 | #else /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */ | |
168 | ||
169 | /** | |
170 | * clockevents_program_min_delta - Set clock event device to the minimum delay. | |
171 | * @dev: device to program | |
172 | * | |
173 | * Returns 0 on success, -ETIME when the retry loop failed. | |
174 | */ | |
175 | static int clockevents_program_min_delta(struct clock_event_device *dev) | |
176 | { | |
177 | unsigned long long clc; | |
178 | int64_t delta; | |
179 | ||
180 | delta = dev->min_delta_ns; | |
181 | dev->next_event = ktime_add_ns(ktime_get(), delta); | |
182 | ||
183 | if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN) | |
184 | return 0; | |
185 | ||
186 | dev->retries++; | |
187 | clc = ((unsigned long long) delta * dev->mult) >> dev->shift; | |
188 | return dev->set_next_event((unsigned long) clc, dev); | |
189 | } | |
190 | ||
191 | #endif /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */ | |
192 | ||
d316c57f TG |
193 | /** |
194 | * clockevents_program_event - Reprogram the clock event device. | |
d1748302 | 195 | * @dev: device to program |
d316c57f | 196 | * @expires: absolute expiry time (monotonic clock) |
d1748302 | 197 | * @force: program minimum delay if expires can not be set |
d316c57f TG |
198 | * |
199 | * Returns 0 on success, -ETIME when the event is in the past. | |
200 | */ | |
201 | int clockevents_program_event(struct clock_event_device *dev, ktime_t expires, | |
d1748302 | 202 | bool force) |
d316c57f TG |
203 | { |
204 | unsigned long long clc; | |
205 | int64_t delta; | |
d1748302 | 206 | int rc; |
d316c57f | 207 | |
167b1de3 TG |
208 | if (unlikely(expires.tv64 < 0)) { |
209 | WARN_ON_ONCE(1); | |
210 | return -ETIME; | |
211 | } | |
212 | ||
d316c57f TG |
213 | dev->next_event = expires; |
214 | ||
215 | if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN) | |
216 | return 0; | |
217 | ||
65516f8a MS |
218 | /* Shortcut for clockevent devices that can deal with ktime. */ |
219 | if (dev->features & CLOCK_EVT_FEAT_KTIME) | |
220 | return dev->set_next_ktime(expires, dev); | |
221 | ||
d1748302 MS |
222 | delta = ktime_to_ns(ktime_sub(expires, ktime_get())); |
223 | if (delta <= 0) | |
224 | return force ? clockevents_program_min_delta(dev) : -ETIME; | |
d316c57f | 225 | |
d1748302 MS |
226 | delta = min(delta, (int64_t) dev->max_delta_ns); |
227 | delta = max(delta, (int64_t) dev->min_delta_ns); | |
d316c57f | 228 | |
d1748302 MS |
229 | clc = ((unsigned long long) delta * dev->mult) >> dev->shift; |
230 | rc = dev->set_next_event((unsigned long) clc, dev); | |
231 | ||
232 | return (rc && force) ? clockevents_program_min_delta(dev) : rc; | |
d316c57f TG |
233 | } |
234 | ||
235 | /** | |
236 | * clockevents_register_notifier - register a clock events change listener | |
237 | */ | |
238 | int clockevents_register_notifier(struct notifier_block *nb) | |
239 | { | |
f833bab8 | 240 | unsigned long flags; |
d316c57f TG |
241 | int ret; |
242 | ||
b5f91da0 | 243 | raw_spin_lock_irqsave(&clockevents_lock, flags); |
d316c57f | 244 | ret = raw_notifier_chain_register(&clockevents_chain, nb); |
b5f91da0 | 245 | raw_spin_unlock_irqrestore(&clockevents_lock, flags); |
d316c57f TG |
246 | |
247 | return ret; | |
248 | } | |
249 | ||
d316c57f TG |
250 | /* |
251 | * Notify about a clock event change. Called with clockevents_lock | |
252 | * held. | |
253 | */ | |
254 | static void clockevents_do_notify(unsigned long reason, void *dev) | |
255 | { | |
256 | raw_notifier_call_chain(&clockevents_chain, reason, dev); | |
257 | } | |
258 | ||
259 | /* | |
3eb05676 | 260 | * Called after a notify add to make devices available which were |
d316c57f TG |
261 | * released from the notifier call. |
262 | */ | |
263 | static void clockevents_notify_released(void) | |
264 | { | |
265 | struct clock_event_device *dev; | |
266 | ||
267 | while (!list_empty(&clockevents_released)) { | |
268 | dev = list_entry(clockevents_released.next, | |
269 | struct clock_event_device, list); | |
270 | list_del(&dev->list); | |
271 | list_add(&dev->list, &clockevent_devices); | |
272 | clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); | |
273 | } | |
274 | } | |
275 | ||
276 | /** | |
277 | * clockevents_register_device - register a clock event device | |
278 | * @dev: device to register | |
279 | */ | |
280 | void clockevents_register_device(struct clock_event_device *dev) | |
281 | { | |
f833bab8 SS |
282 | unsigned long flags; |
283 | ||
d316c57f | 284 | BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED); |
1b054b67 TG |
285 | if (!dev->cpumask) { |
286 | WARN_ON(num_possible_cpus() > 1); | |
287 | dev->cpumask = cpumask_of(smp_processor_id()); | |
288 | } | |
320ab2b0 | 289 | |
b5f91da0 | 290 | raw_spin_lock_irqsave(&clockevents_lock, flags); |
d316c57f TG |
291 | |
292 | list_add(&dev->list, &clockevent_devices); | |
293 | clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); | |
294 | clockevents_notify_released(); | |
295 | ||
b5f91da0 | 296 | raw_spin_unlock_irqrestore(&clockevents_lock, flags); |
d316c57f | 297 | } |
c81fc2c3 | 298 | EXPORT_SYMBOL_GPL(clockevents_register_device); |
d316c57f | 299 | |
e5400321 | 300 | void clockevents_config(struct clock_event_device *dev, u32 freq) |
57f0fcbe | 301 | { |
c0e299b1 | 302 | u64 sec; |
57f0fcbe TG |
303 | |
304 | if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT)) | |
305 | return; | |
306 | ||
307 | /* | |
308 | * Calculate the maximum number of seconds we can sleep. Limit | |
309 | * to 10 minutes for hardware which can program more than | |
310 | * 32bit ticks so we still get reasonable conversion values. | |
311 | */ | |
312 | sec = dev->max_delta_ticks; | |
313 | do_div(sec, freq); | |
314 | if (!sec) | |
315 | sec = 1; | |
316 | else if (sec > 600 && dev->max_delta_ticks > UINT_MAX) | |
317 | sec = 600; | |
318 | ||
319 | clockevents_calc_mult_shift(dev, freq, sec); | |
320 | dev->min_delta_ns = clockevent_delta2ns(dev->min_delta_ticks, dev); | |
321 | dev->max_delta_ns = clockevent_delta2ns(dev->max_delta_ticks, dev); | |
322 | } | |
323 | ||
324 | /** | |
325 | * clockevents_config_and_register - Configure and register a clock event device | |
326 | * @dev: device to register | |
327 | * @freq: The clock frequency | |
328 | * @min_delta: The minimum clock ticks to program in oneshot mode | |
329 | * @max_delta: The maximum clock ticks to program in oneshot mode | |
330 | * | |
331 | * min/max_delta can be 0 for devices which do not support oneshot mode. | |
332 | */ | |
333 | void clockevents_config_and_register(struct clock_event_device *dev, | |
334 | u32 freq, unsigned long min_delta, | |
335 | unsigned long max_delta) | |
336 | { | |
337 | dev->min_delta_ticks = min_delta; | |
338 | dev->max_delta_ticks = max_delta; | |
339 | clockevents_config(dev, freq); | |
340 | clockevents_register_device(dev); | |
341 | } | |
342 | ||
80b816b7 TG |
343 | /** |
344 | * clockevents_update_freq - Update frequency and reprogram a clock event device. | |
345 | * @dev: device to modify | |
346 | * @freq: new device frequency | |
347 | * | |
348 | * Reconfigure and reprogram a clock event device in oneshot | |
349 | * mode. Must be called on the cpu for which the device delivers per | |
350 | * cpu timer events with interrupts disabled! Returns 0 on success, | |
351 | * -ETIME when the event is in the past. | |
352 | */ | |
353 | int clockevents_update_freq(struct clock_event_device *dev, u32 freq) | |
354 | { | |
355 | clockevents_config(dev, freq); | |
356 | ||
357 | if (dev->mode != CLOCK_EVT_MODE_ONESHOT) | |
358 | return 0; | |
359 | ||
d1748302 | 360 | return clockevents_program_event(dev, dev->next_event, false); |
80b816b7 TG |
361 | } |
362 | ||
d316c57f TG |
363 | /* |
364 | * Noop handler when we shut down an event device | |
365 | */ | |
7c1e7689 | 366 | void clockevents_handle_noop(struct clock_event_device *dev) |
d316c57f TG |
367 | { |
368 | } | |
369 | ||
370 | /** | |
371 | * clockevents_exchange_device - release and request clock devices | |
372 | * @old: device to release (can be NULL) | |
373 | * @new: device to request (can be NULL) | |
374 | * | |
375 | * Called from the notifier chain. clockevents_lock is held already | |
376 | */ | |
377 | void clockevents_exchange_device(struct clock_event_device *old, | |
378 | struct clock_event_device *new) | |
379 | { | |
380 | unsigned long flags; | |
381 | ||
382 | local_irq_save(flags); | |
383 | /* | |
384 | * Caller releases a clock event device. We queue it into the | |
385 | * released list and do a notify add later. | |
386 | */ | |
387 | if (old) { | |
d316c57f TG |
388 | clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED); |
389 | list_del(&old->list); | |
390 | list_add(&old->list, &clockevents_released); | |
391 | } | |
392 | ||
393 | if (new) { | |
394 | BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED); | |
2344abbc | 395 | clockevents_shutdown(new); |
d316c57f TG |
396 | } |
397 | local_irq_restore(flags); | |
398 | } | |
399 | ||
de68d9b1 | 400 | #ifdef CONFIG_GENERIC_CLOCKEVENTS |
d316c57f TG |
401 | /** |
402 | * clockevents_notify - notification about relevant events | |
403 | */ | |
404 | void clockevents_notify(unsigned long reason, void *arg) | |
405 | { | |
bb6eddf7 | 406 | struct clock_event_device *dev, *tmp; |
f833bab8 | 407 | unsigned long flags; |
bb6eddf7 | 408 | int cpu; |
0b858e6f | 409 | |
b5f91da0 | 410 | raw_spin_lock_irqsave(&clockevents_lock, flags); |
d316c57f TG |
411 | clockevents_do_notify(reason, arg); |
412 | ||
413 | switch (reason) { | |
414 | case CLOCK_EVT_NOTIFY_CPU_DEAD: | |
415 | /* | |
416 | * Unregister the clock event devices which were | |
417 | * released from the users in the notify chain. | |
418 | */ | |
bb6eddf7 TG |
419 | list_for_each_entry_safe(dev, tmp, &clockevents_released, list) |
420 | list_del(&dev->list); | |
421 | /* | |
422 | * Now check whether the CPU has left unused per cpu devices | |
423 | */ | |
424 | cpu = *((int *)arg); | |
425 | list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) { | |
426 | if (cpumask_test_cpu(cpu, dev->cpumask) && | |
ea9d8e3f XF |
427 | cpumask_weight(dev->cpumask) == 1 && |
428 | !tick_is_broadcast_device(dev)) { | |
bb6eddf7 TG |
429 | BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED); |
430 | list_del(&dev->list); | |
431 | } | |
432 | } | |
d316c57f TG |
433 | break; |
434 | default: | |
435 | break; | |
436 | } | |
b5f91da0 | 437 | raw_spin_unlock_irqrestore(&clockevents_lock, flags); |
d316c57f TG |
438 | } |
439 | EXPORT_SYMBOL_GPL(clockevents_notify); | |
de68d9b1 | 440 | #endif |