Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * This file contains functions which manage clock event devices.
4 : *
5 : * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
6 : * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
7 : * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
8 : */
9 :
10 : #include <linux/clockchips.h>
11 : #include <linux/hrtimer.h>
12 : #include <linux/init.h>
13 : #include <linux/module.h>
14 : #include <linux/smp.h>
15 : #include <linux/device.h>
16 :
17 : #include "tick-internal.h"
18 :
19 : /* The registered clock event devices */
20 : static LIST_HEAD(clockevent_devices);
21 : static LIST_HEAD(clockevents_released);
22 : /* Protection for the above */
23 : static DEFINE_RAW_SPINLOCK(clockevents_lock);
24 : /* Protection for unbind operations */
25 : static DEFINE_MUTEX(clockevents_mutex);
26 :
27 : struct ce_unbind {
28 : struct clock_event_device *ce;
29 : int res;
30 : };
31 :
32 0 : static u64 cev_delta2ns(unsigned long latch, struct clock_event_device *evt,
33 : bool ismax)
34 : {
35 0 : u64 clc = (u64) latch << evt->shift;
36 : u64 rnd;
37 :
38 0 : if (WARN_ON(!evt->mult))
39 0 : evt->mult = 1;
40 0 : rnd = (u64) evt->mult - 1;
41 :
42 : /*
43 : * Upper bound sanity check. If the backwards conversion is
44 : * not equal latch, we know that the above shift overflowed.
45 : */
46 0 : if ((clc >> evt->shift) != (u64)latch)
47 0 : clc = ~0ULL;
48 :
49 : /*
50 : * Scaled math oddities:
51 : *
52 : * For mult <= (1 << shift) we can safely add mult - 1 to
53 : * prevent integer rounding loss. So the backwards conversion
54 : * from nsec to device ticks will be correct.
55 : *
56 : * For mult > (1 << shift), i.e. device frequency is > 1GHz we
57 : * need to be careful. Adding mult - 1 will result in a value
58 : * which when converted back to device ticks can be larger
59 : * than latch by up to (mult - 1) >> shift. For the min_delta
60 : * calculation we still want to apply this in order to stay
61 : * above the minimum device ticks limit. For the upper limit
62 : * we would end up with a latch value larger than the upper
63 : * limit of the device, so we omit the add to stay below the
64 : * device upper boundary.
65 : *
66 : * Also omit the add if it would overflow the u64 boundary.
67 : */
68 0 : if ((~0ULL - clc > rnd) &&
69 0 : (!ismax || evt->mult <= (1ULL << evt->shift)))
70 0 : clc += rnd;
71 :
72 0 : do_div(clc, evt->mult);
73 :
74 : /* Deltas less than 1usec are pointless noise */
75 0 : return clc > 1000 ? clc : 1000;
76 : }
77 :
78 : /**
79 : * clockevent_delta2ns - Convert a latch value (device ticks) to nanoseconds
80 : * @latch: value to convert
81 : * @evt: pointer to clock event device descriptor
82 : *
83 : * Math helper, returns latch value converted to nanoseconds (bound checked)
84 : */
85 0 : u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
86 : {
87 0 : return cev_delta2ns(latch, evt, false);
88 : }
89 : EXPORT_SYMBOL_GPL(clockevent_delta2ns);
90 :
91 2 : static int __clockevents_switch_state(struct clock_event_device *dev,
92 : enum clock_event_state state)
93 : {
94 2 : if (dev->features & CLOCK_EVT_FEAT_DUMMY)
95 : return 0;
96 :
97 : /* Transition with new state-specific callbacks */
98 2 : switch (state) {
99 : case CLOCK_EVT_STATE_DETACHED:
100 : /* The clockevent device is getting replaced. Shut it down. */
101 :
102 : case CLOCK_EVT_STATE_SHUTDOWN:
103 1 : if (dev->set_state_shutdown)
104 1 : return dev->set_state_shutdown(dev);
105 : return 0;
106 :
107 : case CLOCK_EVT_STATE_PERIODIC:
108 : /* Core internal bug */
109 1 : if (!(dev->features & CLOCK_EVT_FEAT_PERIODIC))
110 : return -ENOSYS;
111 1 : if (dev->set_state_periodic)
112 1 : return dev->set_state_periodic(dev);
113 : return 0;
114 :
115 : case CLOCK_EVT_STATE_ONESHOT:
116 : /* Core internal bug */
117 0 : if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
118 : return -ENOSYS;
119 0 : if (dev->set_state_oneshot)
120 0 : return dev->set_state_oneshot(dev);
121 : return 0;
122 :
123 : case CLOCK_EVT_STATE_ONESHOT_STOPPED:
124 : /* Core internal bug */
125 0 : if (WARN_ONCE(!clockevent_state_oneshot(dev),
126 : "Current state: %d\n",
127 : clockevent_get_state(dev)))
128 : return -EINVAL;
129 :
130 0 : if (dev->set_state_oneshot_stopped)
131 0 : return dev->set_state_oneshot_stopped(dev);
132 : else
133 : return -ENOSYS;
134 :
135 : default:
136 : return -ENOSYS;
137 : }
138 : }
139 :
140 : /**
141 : * clockevents_switch_state - set the operating state of a clock event device
142 : * @dev: device to modify
143 : * @state: new state
144 : *
145 : * Must be called with interrupts disabled !
146 : */
147 2 : void clockevents_switch_state(struct clock_event_device *dev,
148 : enum clock_event_state state)
149 : {
150 2 : if (clockevent_get_state(dev) != state) {
151 2 : if (__clockevents_switch_state(dev, state))
152 : return;
153 :
154 4 : clockevent_set_state(dev, state);
155 :
156 : /*
157 : * A nsec2cyc multiplicator of 0 is invalid and we'd crash
158 : * on it, so fix it up and emit a warning:
159 : */
160 2 : if (clockevent_state_oneshot(dev)) {
161 0 : if (WARN_ON(!dev->mult))
162 0 : dev->mult = 1;
163 : }
164 : }
165 : }
166 :
167 : /**
168 : * clockevents_shutdown - shutdown the device and clear next_event
169 : * @dev: device to shutdown
170 : */
171 0 : void clockevents_shutdown(struct clock_event_device *dev)
172 : {
173 1 : clockevents_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
174 1 : dev->next_event = KTIME_MAX;
175 0 : }
176 :
177 : /**
178 : * clockevents_tick_resume - Resume the tick device before using it again
179 : * @dev: device to resume
180 : */
181 0 : int clockevents_tick_resume(struct clock_event_device *dev)
182 : {
183 0 : int ret = 0;
184 :
185 0 : if (dev->tick_resume)
186 0 : ret = dev->tick_resume(dev);
187 :
188 0 : return ret;
189 : }
190 :
191 : #ifdef CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST
192 :
193 : /* Limit min_delta to a jiffie */
194 : #define MIN_DELTA_LIMIT (NSEC_PER_SEC / HZ)
195 :
196 : /**
197 : * clockevents_increase_min_delta - raise minimum delta of a clock event device
198 : * @dev: device to increase the minimum delta
199 : *
200 : * Returns 0 on success, -ETIME when the minimum delta reached the limit.
201 : */
202 : static int clockevents_increase_min_delta(struct clock_event_device *dev)
203 : {
204 : /* Nothing to do if we already reached the limit */
205 : if (dev->min_delta_ns >= MIN_DELTA_LIMIT) {
206 : printk_deferred(KERN_WARNING
207 : "CE: Reprogramming failure. Giving up\n");
208 : dev->next_event = KTIME_MAX;
209 : return -ETIME;
210 : }
211 :
212 : if (dev->min_delta_ns < 5000)
213 : dev->min_delta_ns = 5000;
214 : else
215 : dev->min_delta_ns += dev->min_delta_ns >> 1;
216 :
217 : if (dev->min_delta_ns > MIN_DELTA_LIMIT)
218 : dev->min_delta_ns = MIN_DELTA_LIMIT;
219 :
220 : printk_deferred(KERN_WARNING
221 : "CE: %s increased min_delta_ns to %llu nsec\n",
222 : dev->name ? dev->name : "?",
223 : (unsigned long long) dev->min_delta_ns);
224 : return 0;
225 : }
226 :
227 : /**
228 : * clockevents_program_min_delta - Set clock event device to the minimum delay.
229 : * @dev: device to program
230 : *
231 : * Returns 0 on success, -ETIME when the retry loop failed.
232 : */
233 : static int clockevents_program_min_delta(struct clock_event_device *dev)
234 : {
235 : unsigned long long clc;
236 : int64_t delta;
237 : int i;
238 :
239 : for (i = 0;;) {
240 : delta = dev->min_delta_ns;
241 : dev->next_event = ktime_add_ns(ktime_get(), delta);
242 :
243 : if (clockevent_state_shutdown(dev))
244 : return 0;
245 :
246 : dev->retries++;
247 : clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
248 : if (dev->set_next_event((unsigned long) clc, dev) == 0)
249 : return 0;
250 :
251 : if (++i > 2) {
252 : /*
253 : * We tried 3 times to program the device with the
254 : * given min_delta_ns. Try to increase the minimum
255 : * delta, if that fails as well get out of here.
256 : */
257 : if (clockevents_increase_min_delta(dev))
258 : return -ETIME;
259 : i = 0;
260 : }
261 : }
262 : }
263 :
264 : #else /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */
265 :
266 : /**
267 : * clockevents_program_min_delta - Set clock event device to the minimum delay.
268 : * @dev: device to program
269 : *
270 : * Returns 0 on success, -ETIME when the retry loop failed.
271 : */
272 0 : static int clockevents_program_min_delta(struct clock_event_device *dev)
273 : {
274 : unsigned long long clc;
275 0 : int64_t delta = 0;
276 : int i;
277 :
278 0 : for (i = 0; i < 10; i++) {
279 0 : delta += dev->min_delta_ns;
280 0 : dev->next_event = ktime_add_ns(ktime_get(), delta);
281 :
282 0 : if (clockevent_state_shutdown(dev))
283 : return 0;
284 :
285 0 : dev->retries++;
286 0 : clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
287 0 : if (dev->set_next_event((unsigned long) clc, dev) == 0)
288 : return 0;
289 : }
290 : return -ETIME;
291 : }
292 :
293 : #endif /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */
294 :
295 : /**
296 : * clockevents_program_event - Reprogram the clock event device.
297 : * @dev: device to program
298 : * @expires: absolute expiry time (monotonic clock)
299 : * @force: program minimum delay if expires can not be set
300 : *
301 : * Returns 0 on success, -ETIME when the event is in the past.
302 : */
303 0 : int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
304 : bool force)
305 : {
306 : unsigned long long clc;
307 : int64_t delta;
308 : int rc;
309 :
310 0 : if (WARN_ON_ONCE(expires < 0))
311 : return -ETIME;
312 :
313 0 : dev->next_event = expires;
314 :
315 0 : if (clockevent_state_shutdown(dev))
316 : return 0;
317 :
318 : /* We must be in ONESHOT state here */
319 0 : WARN_ONCE(!clockevent_state_oneshot(dev), "Current state: %d\n",
320 : clockevent_get_state(dev));
321 :
322 : /* Shortcut for clockevent devices that can deal with ktime. */
323 0 : if (dev->features & CLOCK_EVT_FEAT_KTIME)
324 0 : return dev->set_next_ktime(expires, dev);
325 :
326 0 : delta = ktime_to_ns(ktime_sub(expires, ktime_get()));
327 0 : if (delta <= 0)
328 0 : return force ? clockevents_program_min_delta(dev) : -ETIME;
329 :
330 0 : delta = min(delta, (int64_t) dev->max_delta_ns);
331 0 : delta = max(delta, (int64_t) dev->min_delta_ns);
332 :
333 0 : clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
334 0 : rc = dev->set_next_event((unsigned long) clc, dev);
335 :
336 0 : return (rc && force) ? clockevents_program_min_delta(dev) : rc;
337 : }
338 :
339 : /*
340 : * Called after a notify add to make devices available which were
341 : * released from the notifier call.
342 : */
343 1 : static void clockevents_notify_released(void)
344 : {
345 : struct clock_event_device *dev;
346 :
347 2 : while (!list_empty(&clockevents_released)) {
348 0 : dev = list_entry(clockevents_released.next,
349 : struct clock_event_device, list);
350 0 : list_move(&dev->list, &clockevent_devices);
351 0 : tick_check_new_device(dev);
352 : }
353 1 : }
354 :
355 : /*
356 : * Try to install a replacement clock event device
357 : */
358 0 : static int clockevents_replace(struct clock_event_device *ced)
359 : {
360 0 : struct clock_event_device *dev, *newdev = NULL;
361 :
362 0 : list_for_each_entry(dev, &clockevent_devices, list) {
363 0 : if (dev == ced || !clockevent_state_detached(dev))
364 0 : continue;
365 :
366 0 : if (!tick_check_replacement(newdev, dev))
367 0 : continue;
368 :
369 : if (!try_module_get(dev->owner))
370 : continue;
371 :
372 : if (newdev)
373 : module_put(newdev->owner);
374 : newdev = dev;
375 : }
376 0 : if (newdev) {
377 0 : tick_install_replacement(newdev);
378 0 : list_del_init(&ced->list);
379 : }
380 0 : return newdev ? 0 : -EBUSY;
381 : }
382 :
383 : /*
384 : * Called with clockevents_mutex and clockevents_lock held
385 : */
386 : static int __clockevents_try_unbind(struct clock_event_device *ced, int cpu)
387 : {
388 : /* Fast track. Device is unused */
389 0 : if (clockevent_state_detached(ced)) {
390 0 : list_del_init(&ced->list);
391 : return 0;
392 : }
393 :
394 0 : return ced == per_cpu(tick_cpu_device, cpu).evtdev ? -EAGAIN : -EBUSY;
395 : }
396 :
397 : /*
398 : * SMP function call to unbind a device
399 : */
400 0 : static void __clockevents_unbind(void *arg)
401 : {
402 0 : struct ce_unbind *cu = arg;
403 : int res;
404 :
405 0 : raw_spin_lock(&clockevents_lock);
406 0 : res = __clockevents_try_unbind(cu->ce, smp_processor_id());
407 0 : if (res == -EAGAIN)
408 0 : res = clockevents_replace(cu->ce);
409 0 : cu->res = res;
410 0 : raw_spin_unlock(&clockevents_lock);
411 0 : }
412 :
413 : /*
414 : * Issues smp function call to unbind a per cpu device. Called with
415 : * clockevents_mutex held.
416 : */
417 : static int clockevents_unbind(struct clock_event_device *ced, int cpu)
418 : {
419 0 : struct ce_unbind cu = { .ce = ced, .res = -ENODEV };
420 :
421 0 : smp_call_function_single(cpu, __clockevents_unbind, &cu, 1);
422 0 : return cu.res;
423 : }
424 :
425 : /*
426 : * Unbind a clockevents device.
427 : */
428 0 : int clockevents_unbind_device(struct clock_event_device *ced, int cpu)
429 : {
430 : int ret;
431 :
432 0 : mutex_lock(&clockevents_mutex);
433 0 : ret = clockevents_unbind(ced, cpu);
434 0 : mutex_unlock(&clockevents_mutex);
435 0 : return ret;
436 : }
437 : EXPORT_SYMBOL_GPL(clockevents_unbind_device);
438 :
439 : /**
440 : * clockevents_register_device - register a clock event device
441 : * @dev: device to register
442 : */
443 1 : void clockevents_register_device(struct clock_event_device *dev)
444 : {
445 : unsigned long flags;
446 :
447 : /* Initialize state to DETACHED */
448 2 : clockevent_set_state(dev, CLOCK_EVT_STATE_DETACHED);
449 :
450 1 : if (!dev->cpumask) {
451 0 : WARN_ON(num_possible_cpus() > 1);
452 0 : dev->cpumask = cpumask_of(smp_processor_id());
453 : }
454 :
455 1 : if (dev->cpumask == cpu_all_mask) {
456 0 : WARN(1, "%s cpumask == cpu_all_mask, using cpu_possible_mask instead\n",
457 : dev->name);
458 0 : dev->cpumask = cpu_possible_mask;
459 : }
460 :
461 1 : raw_spin_lock_irqsave(&clockevents_lock, flags);
462 :
463 2 : list_add(&dev->list, &clockevent_devices);
464 1 : tick_check_new_device(dev);
465 1 : clockevents_notify_released();
466 :
467 2 : raw_spin_unlock_irqrestore(&clockevents_lock, flags);
468 1 : }
469 : EXPORT_SYMBOL_GPL(clockevents_register_device);
470 :
471 0 : static void clockevents_config(struct clock_event_device *dev, u32 freq)
472 : {
473 : u64 sec;
474 :
475 0 : if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
476 : return;
477 :
478 : /*
479 : * Calculate the maximum number of seconds we can sleep. Limit
480 : * to 10 minutes for hardware which can program more than
481 : * 32bit ticks so we still get reasonable conversion values.
482 : */
483 0 : sec = dev->max_delta_ticks;
484 0 : do_div(sec, freq);
485 0 : if (!sec)
486 : sec = 1;
487 0 : else if (sec > 600 && dev->max_delta_ticks > UINT_MAX)
488 0 : sec = 600;
489 :
490 0 : clockevents_calc_mult_shift(dev, freq, sec);
491 0 : dev->min_delta_ns = cev_delta2ns(dev->min_delta_ticks, dev, false);
492 0 : dev->max_delta_ns = cev_delta2ns(dev->max_delta_ticks, dev, true);
493 : }
494 :
495 : /**
496 : * clockevents_config_and_register - Configure and register a clock event device
497 : * @dev: device to register
498 : * @freq: The clock frequency
499 : * @min_delta: The minimum clock ticks to program in oneshot mode
500 : * @max_delta: The maximum clock ticks to program in oneshot mode
501 : *
502 : * min/max_delta can be 0 for devices which do not support oneshot mode.
503 : */
504 0 : void clockevents_config_and_register(struct clock_event_device *dev,
505 : u32 freq, unsigned long min_delta,
506 : unsigned long max_delta)
507 : {
508 0 : dev->min_delta_ticks = min_delta;
509 0 : dev->max_delta_ticks = max_delta;
510 0 : clockevents_config(dev, freq);
511 0 : clockevents_register_device(dev);
512 0 : }
513 : EXPORT_SYMBOL_GPL(clockevents_config_and_register);
514 :
515 0 : int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)
516 : {
517 0 : clockevents_config(dev, freq);
518 :
519 0 : if (clockevent_state_oneshot(dev))
520 0 : return clockevents_program_event(dev, dev->next_event, false);
521 :
522 0 : if (clockevent_state_periodic(dev))
523 0 : return __clockevents_switch_state(dev, CLOCK_EVT_STATE_PERIODIC);
524 :
525 : return 0;
526 : }
527 :
528 : /**
529 : * clockevents_update_freq - Update frequency and reprogram a clock event device.
530 : * @dev: device to modify
531 : * @freq: new device frequency
532 : *
533 : * Reconfigure and reprogram a clock event device in oneshot
534 : * mode. Must be called on the cpu for which the device delivers per
535 : * cpu timer events. If called for the broadcast device the core takes
536 : * care of serialization.
537 : *
538 : * Returns 0 on success, -ETIME when the event is in the past.
539 : */
540 0 : int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
541 : {
542 : unsigned long flags;
543 : int ret;
544 :
545 0 : local_irq_save(flags);
546 0 : ret = tick_broadcast_update_freq(dev, freq);
547 : if (ret == -ENODEV)
548 0 : ret = __clockevents_update_freq(dev, freq);
549 0 : local_irq_restore(flags);
550 0 : return ret;
551 : }
552 :
553 : /*
554 : * Noop handler when we shut down an event device
555 : */
556 0 : void clockevents_handle_noop(struct clock_event_device *dev)
557 : {
558 0 : }
559 :
560 : /**
561 : * clockevents_exchange_device - release and request clock devices
562 : * @old: device to release (can be NULL)
563 : * @new: device to request (can be NULL)
564 : *
565 : * Called from various tick functions with clockevents_lock held and
566 : * interrupts disabled.
567 : */
568 1 : void clockevents_exchange_device(struct clock_event_device *old,
569 : struct clock_event_device *new)
570 : {
571 : /*
572 : * Caller releases a clock event device. We queue it into the
573 : * released list and do a notify add later.
574 : */
575 1 : if (old) {
576 0 : module_put(old->owner);
577 0 : clockevents_switch_state(old, CLOCK_EVT_STATE_DETACHED);
578 0 : list_move(&old->list, &clockevents_released);
579 : }
580 :
581 1 : if (new) {
582 1 : BUG_ON(!clockevent_state_detached(new));
583 : clockevents_shutdown(new);
584 : }
585 1 : }
586 :
587 : /**
588 : * clockevents_suspend - suspend clock devices
589 : */
590 0 : void clockevents_suspend(void)
591 : {
592 : struct clock_event_device *dev;
593 :
594 0 : list_for_each_entry_reverse(dev, &clockevent_devices, list)
595 0 : if (dev->suspend && !clockevent_state_detached(dev))
596 0 : dev->suspend(dev);
597 0 : }
598 :
599 : /**
600 : * clockevents_resume - resume clock devices
601 : */
602 0 : void clockevents_resume(void)
603 : {
604 : struct clock_event_device *dev;
605 :
606 0 : list_for_each_entry(dev, &clockevent_devices, list)
607 0 : if (dev->resume && !clockevent_state_detached(dev))
608 0 : dev->resume(dev);
609 0 : }
610 :
611 : #ifdef CONFIG_HOTPLUG_CPU
612 :
613 : # ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
614 : /**
615 : * tick_offline_cpu - Take CPU out of the broadcast mechanism
616 : * @cpu: The outgoing CPU
617 : *
618 : * Called on the outgoing CPU after it took itself offline.
619 : */
620 : void tick_offline_cpu(unsigned int cpu)
621 : {
622 : raw_spin_lock(&clockevents_lock);
623 : tick_broadcast_offline(cpu);
624 : raw_spin_unlock(&clockevents_lock);
625 : }
626 : # endif
627 :
628 : /**
629 : * tick_cleanup_dead_cpu - Cleanup the tick and clockevents of a dead cpu
630 : * @cpu: The dead CPU
631 : */
632 : void tick_cleanup_dead_cpu(int cpu)
633 : {
634 : struct clock_event_device *dev, *tmp;
635 : unsigned long flags;
636 :
637 : raw_spin_lock_irqsave(&clockevents_lock, flags);
638 :
639 : tick_shutdown(cpu);
640 : /*
641 : * Unregister the clock event devices which were
642 : * released from the users in the notify chain.
643 : */
644 : list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
645 : list_del(&dev->list);
646 : /*
647 : * Now check whether the CPU has left unused per cpu devices
648 : */
649 : list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
650 : if (cpumask_test_cpu(cpu, dev->cpumask) &&
651 : cpumask_weight(dev->cpumask) == 1 &&
652 : !tick_is_broadcast_device(dev)) {
653 : BUG_ON(!clockevent_state_detached(dev));
654 : list_del(&dev->list);
655 : }
656 : }
657 : raw_spin_unlock_irqrestore(&clockevents_lock, flags);
658 : }
659 : #endif
660 :
661 : #ifdef CONFIG_SYSFS
662 : static struct bus_type clockevents_subsys = {
663 : .name = "clockevents",
664 : .dev_name = "clockevent",
665 : };
666 :
667 : static DEFINE_PER_CPU(struct device, tick_percpu_dev);
668 : static struct tick_device *tick_get_tick_dev(struct device *dev);
669 :
670 0 : static ssize_t current_device_show(struct device *dev,
671 : struct device_attribute *attr,
672 : char *buf)
673 : {
674 : struct tick_device *td;
675 0 : ssize_t count = 0;
676 :
677 0 : raw_spin_lock_irq(&clockevents_lock);
678 0 : td = tick_get_tick_dev(dev);
679 0 : if (td && td->evtdev)
680 0 : count = snprintf(buf, PAGE_SIZE, "%s\n", td->evtdev->name);
681 0 : raw_spin_unlock_irq(&clockevents_lock);
682 0 : return count;
683 : }
684 : static DEVICE_ATTR_RO(current_device);
685 :
686 : /* We don't support the abomination of removable broadcast devices */
687 0 : static ssize_t unbind_device_store(struct device *dev,
688 : struct device_attribute *attr,
689 : const char *buf, size_t count)
690 : {
691 : char name[CS_NAME_LEN];
692 0 : ssize_t ret = sysfs_get_uname(buf, name, count);
693 0 : struct clock_event_device *ce = NULL, *iter;
694 :
695 0 : if (ret < 0)
696 : return ret;
697 :
698 0 : ret = -ENODEV;
699 0 : mutex_lock(&clockevents_mutex);
700 0 : raw_spin_lock_irq(&clockevents_lock);
701 0 : list_for_each_entry(iter, &clockevent_devices, list) {
702 0 : if (!strcmp(iter->name, name)) {
703 0 : ret = __clockevents_try_unbind(iter, dev->id);
704 0 : ce = iter;
705 0 : break;
706 : }
707 : }
708 0 : raw_spin_unlock_irq(&clockevents_lock);
709 : /*
710 : * We hold clockevents_mutex, so ce can't go away
711 : */
712 0 : if (ret == -EAGAIN)
713 0 : ret = clockevents_unbind(ce, dev->id);
714 0 : mutex_unlock(&clockevents_mutex);
715 0 : return ret ? ret : count;
716 : }
717 : static DEVICE_ATTR_WO(unbind_device);
718 :
719 : #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
720 : static struct device tick_bc_dev = {
721 : .init_name = "broadcast",
722 : .id = 0,
723 : .bus = &clockevents_subsys,
724 : };
725 :
726 : static struct tick_device *tick_get_tick_dev(struct device *dev)
727 : {
728 : return dev == &tick_bc_dev ? tick_get_broadcast_device() :
729 : &per_cpu(tick_cpu_device, dev->id);
730 : }
731 :
732 : static __init int tick_broadcast_init_sysfs(void)
733 : {
734 : int err = device_register(&tick_bc_dev);
735 :
736 : if (!err)
737 : err = device_create_file(&tick_bc_dev, &dev_attr_current_device);
738 : return err;
739 : }
740 : #else
741 : static struct tick_device *tick_get_tick_dev(struct device *dev)
742 : {
743 0 : return &per_cpu(tick_cpu_device, dev->id);
744 : }
745 : static inline int tick_broadcast_init_sysfs(void) { return 0; }
746 : #endif
747 :
748 1 : static int __init tick_init_sysfs(void)
749 : {
750 : int cpu;
751 :
752 2 : for_each_possible_cpu(cpu) {
753 1 : struct device *dev = &per_cpu(tick_percpu_dev, cpu);
754 : int err;
755 :
756 1 : dev->id = cpu;
757 1 : dev->bus = &clockevents_subsys;
758 1 : err = device_register(dev);
759 1 : if (!err)
760 1 : err = device_create_file(dev, &dev_attr_current_device);
761 1 : if (!err)
762 1 : err = device_create_file(dev, &dev_attr_unbind_device);
763 1 : if (err)
764 : return err;
765 : }
766 : return tick_broadcast_init_sysfs();
767 : }
768 :
769 1 : static int __init clockevents_init_sysfs(void)
770 : {
771 1 : int err = subsys_system_register(&clockevents_subsys, NULL);
772 :
773 1 : if (!err)
774 1 : err = tick_init_sysfs();
775 1 : return err;
776 : }
777 : device_initcall(clockevents_init_sysfs);
778 : #endif /* SYSFS */
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