xref: /openbmc/linux/kernel/time/clockevents.c (revision 23c2b932)
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/smp.h>
19 #include <linux/device.h>
20 
21 #include "tick-internal.h"
22 
23 /* The registered clock event devices */
24 static LIST_HEAD(clockevent_devices);
25 static LIST_HEAD(clockevents_released);
26 /* Protection for the above */
27 static DEFINE_RAW_SPINLOCK(clockevents_lock);
28 /* Protection for unbind operations */
29 static DEFINE_MUTEX(clockevents_mutex);
30 
31 struct ce_unbind {
32 	struct clock_event_device *ce;
33 	int res;
34 };
35 
36 static u64 cev_delta2ns(unsigned long latch, struct clock_event_device *evt,
37 			bool ismax)
38 {
39 	u64 clc = (u64) latch << evt->shift;
40 	u64 rnd;
41 
42 	if (unlikely(!evt->mult)) {
43 		evt->mult = 1;
44 		WARN_ON(1);
45 	}
46 	rnd = (u64) evt->mult - 1;
47 
48 	/*
49 	 * Upper bound sanity check. If the backwards conversion is
50 	 * not equal latch, we know that the above shift overflowed.
51 	 */
52 	if ((clc >> evt->shift) != (u64)latch)
53 		clc = ~0ULL;
54 
55 	/*
56 	 * Scaled math oddities:
57 	 *
58 	 * For mult <= (1 << shift) we can safely add mult - 1 to
59 	 * prevent integer rounding loss. So the backwards conversion
60 	 * from nsec to device ticks will be correct.
61 	 *
62 	 * For mult > (1 << shift), i.e. device frequency is > 1GHz we
63 	 * need to be careful. Adding mult - 1 will result in a value
64 	 * which when converted back to device ticks can be larger
65 	 * than latch by up to (mult - 1) >> shift. For the min_delta
66 	 * calculation we still want to apply this in order to stay
67 	 * above the minimum device ticks limit. For the upper limit
68 	 * we would end up with a latch value larger than the upper
69 	 * limit of the device, so we omit the add to stay below the
70 	 * device upper boundary.
71 	 *
72 	 * Also omit the add if it would overflow the u64 boundary.
73 	 */
74 	if ((~0ULL - clc > rnd) &&
75 	    (!ismax || evt->mult <= (1ULL << evt->shift)))
76 		clc += rnd;
77 
78 	do_div(clc, evt->mult);
79 
80 	/* Deltas less than 1usec are pointless noise */
81 	return clc > 1000 ? clc : 1000;
82 }
83 
84 /**
85  * clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds
86  * @latch:	value to convert
87  * @evt:	pointer to clock event device descriptor
88  *
89  * Math helper, returns latch value converted to nanoseconds (bound checked)
90  */
91 u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
92 {
93 	return cev_delta2ns(latch, evt, false);
94 }
95 EXPORT_SYMBOL_GPL(clockevent_delta2ns);
96 
97 static int __clockevents_switch_state(struct clock_event_device *dev,
98 				      enum clock_event_state state)
99 {
100 	if (dev->features & CLOCK_EVT_FEAT_DUMMY)
101 		return 0;
102 
103 	/* Transition with new state-specific callbacks */
104 	switch (state) {
105 	case CLOCK_EVT_STATE_DETACHED:
106 		/* The clockevent device is getting replaced. Shut it down. */
107 
108 	case CLOCK_EVT_STATE_SHUTDOWN:
109 		if (dev->set_state_shutdown)
110 			return dev->set_state_shutdown(dev);
111 		return 0;
112 
113 	case CLOCK_EVT_STATE_PERIODIC:
114 		/* Core internal bug */
115 		if (!(dev->features & CLOCK_EVT_FEAT_PERIODIC))
116 			return -ENOSYS;
117 		if (dev->set_state_periodic)
118 			return dev->set_state_periodic(dev);
119 		return 0;
120 
121 	case CLOCK_EVT_STATE_ONESHOT:
122 		/* Core internal bug */
123 		if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
124 			return -ENOSYS;
125 		if (dev->set_state_oneshot)
126 			return dev->set_state_oneshot(dev);
127 		return 0;
128 
129 	case CLOCK_EVT_STATE_ONESHOT_STOPPED:
130 		/* Core internal bug */
131 		if (WARN_ONCE(!clockevent_state_oneshot(dev),
132 			      "Current state: %d\n",
133 			      clockevent_get_state(dev)))
134 			return -EINVAL;
135 
136 		if (dev->set_state_oneshot_stopped)
137 			return dev->set_state_oneshot_stopped(dev);
138 		else
139 			return -ENOSYS;
140 
141 	default:
142 		return -ENOSYS;
143 	}
144 }
145 
146 /**
147  * clockevents_switch_state - set the operating state of a clock event device
148  * @dev:	device to modify
149  * @state:	new state
150  *
151  * Must be called with interrupts disabled !
152  */
153 void clockevents_switch_state(struct clock_event_device *dev,
154 			      enum clock_event_state state)
155 {
156 	if (clockevent_get_state(dev) != state) {
157 		if (__clockevents_switch_state(dev, state))
158 			return;
159 
160 		clockevent_set_state(dev, state);
161 
162 		/*
163 		 * A nsec2cyc multiplicator of 0 is invalid and we'd crash
164 		 * on it, so fix it up and emit a warning:
165 		 */
166 		if (clockevent_state_oneshot(dev)) {
167 			if (unlikely(!dev->mult)) {
168 				dev->mult = 1;
169 				WARN_ON(1);
170 			}
171 		}
172 	}
173 }
174 
175 /**
176  * clockevents_shutdown - shutdown the device and clear next_event
177  * @dev:	device to shutdown
178  */
179 void clockevents_shutdown(struct clock_event_device *dev)
180 {
181 	clockevents_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
182 	dev->next_event.tv64 = KTIME_MAX;
183 }
184 
185 /**
186  * clockevents_tick_resume -	Resume the tick device before using it again
187  * @dev:			device to resume
188  */
189 int clockevents_tick_resume(struct clock_event_device *dev)
190 {
191 	int ret = 0;
192 
193 	if (dev->tick_resume)
194 		ret = dev->tick_resume(dev);
195 
196 	return ret;
197 }
198 
199 #ifdef CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST
200 
201 /* Limit min_delta to a jiffie */
202 #define MIN_DELTA_LIMIT		(NSEC_PER_SEC / HZ)
203 
204 /**
205  * clockevents_increase_min_delta - raise minimum delta of a clock event device
206  * @dev:       device to increase the minimum delta
207  *
208  * Returns 0 on success, -ETIME when the minimum delta reached the limit.
209  */
210 static int clockevents_increase_min_delta(struct clock_event_device *dev)
211 {
212 	/* Nothing to do if we already reached the limit */
213 	if (dev->min_delta_ns >= MIN_DELTA_LIMIT) {
214 		printk_deferred(KERN_WARNING
215 				"CE: Reprogramming failure. Giving up\n");
216 		dev->next_event.tv64 = KTIME_MAX;
217 		return -ETIME;
218 	}
219 
220 	if (dev->min_delta_ns < 5000)
221 		dev->min_delta_ns = 5000;
222 	else
223 		dev->min_delta_ns += dev->min_delta_ns >> 1;
224 
225 	if (dev->min_delta_ns > MIN_DELTA_LIMIT)
226 		dev->min_delta_ns = MIN_DELTA_LIMIT;
227 
228 	printk_deferred(KERN_WARNING
229 			"CE: %s increased min_delta_ns to %llu nsec\n",
230 			dev->name ? dev->name : "?",
231 			(unsigned long long) dev->min_delta_ns);
232 	return 0;
233 }
234 
235 /**
236  * clockevents_program_min_delta - Set clock event device to the minimum delay.
237  * @dev:	device to program
238  *
239  * Returns 0 on success, -ETIME when the retry loop failed.
240  */
241 static int clockevents_program_min_delta(struct clock_event_device *dev)
242 {
243 	unsigned long long clc;
244 	int64_t delta;
245 	int i;
246 
247 	for (i = 0;;) {
248 		delta = dev->min_delta_ns;
249 		dev->next_event = ktime_add_ns(ktime_get(), delta);
250 
251 		if (clockevent_state_shutdown(dev))
252 			return 0;
253 
254 		dev->retries++;
255 		clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
256 		if (dev->set_next_event((unsigned long) clc, dev) == 0)
257 			return 0;
258 
259 		if (++i > 2) {
260 			/*
261 			 * We tried 3 times to program the device with the
262 			 * given min_delta_ns. Try to increase the minimum
263 			 * delta, if that fails as well get out of here.
264 			 */
265 			if (clockevents_increase_min_delta(dev))
266 				return -ETIME;
267 			i = 0;
268 		}
269 	}
270 }
271 
272 #else  /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */
273 
274 /**
275  * clockevents_program_min_delta - Set clock event device to the minimum delay.
276  * @dev:	device to program
277  *
278  * Returns 0 on success, -ETIME when the retry loop failed.
279  */
280 static int clockevents_program_min_delta(struct clock_event_device *dev)
281 {
282 	unsigned long long clc;
283 	int64_t delta;
284 
285 	delta = dev->min_delta_ns;
286 	dev->next_event = ktime_add_ns(ktime_get(), delta);
287 
288 	if (clockevent_state_shutdown(dev))
289 		return 0;
290 
291 	dev->retries++;
292 	clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
293 	return dev->set_next_event((unsigned long) clc, dev);
294 }
295 
296 #endif /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */
297 
298 /**
299  * clockevents_program_event - Reprogram the clock event device.
300  * @dev:	device to program
301  * @expires:	absolute expiry time (monotonic clock)
302  * @force:	program minimum delay if expires can not be set
303  *
304  * Returns 0 on success, -ETIME when the event is in the past.
305  */
306 int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
307 			      bool force)
308 {
309 	unsigned long long clc;
310 	int64_t delta;
311 	int rc;
312 
313 	if (unlikely(expires.tv64 < 0)) {
314 		WARN_ON_ONCE(1);
315 		return -ETIME;
316 	}
317 
318 	dev->next_event = expires;
319 
320 	if (clockevent_state_shutdown(dev))
321 		return 0;
322 
323 	/* We must be in ONESHOT state here */
324 	WARN_ONCE(!clockevent_state_oneshot(dev), "Current state: %d\n",
325 		  clockevent_get_state(dev));
326 
327 	/* Shortcut for clockevent devices that can deal with ktime. */
328 	if (dev->features & CLOCK_EVT_FEAT_KTIME)
329 		return dev->set_next_ktime(expires, dev);
330 
331 	delta = ktime_to_ns(ktime_sub(expires, ktime_get()));
332 	if (delta <= 0)
333 		return force ? clockevents_program_min_delta(dev) : -ETIME;
334 
335 	delta = min(delta, (int64_t) dev->max_delta_ns);
336 	delta = max(delta, (int64_t) dev->min_delta_ns);
337 
338 	clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
339 	rc = dev->set_next_event((unsigned long) clc, dev);
340 
341 	return (rc && force) ? clockevents_program_min_delta(dev) : rc;
342 }
343 
344 /*
345  * Called after a notify add to make devices available which were
346  * released from the notifier call.
347  */
348 static void clockevents_notify_released(void)
349 {
350 	struct clock_event_device *dev;
351 
352 	while (!list_empty(&clockevents_released)) {
353 		dev = list_entry(clockevents_released.next,
354 				 struct clock_event_device, list);
355 		list_del(&dev->list);
356 		list_add(&dev->list, &clockevent_devices);
357 		tick_check_new_device(dev);
358 	}
359 }
360 
361 /*
362  * Try to install a replacement clock event device
363  */
364 static int clockevents_replace(struct clock_event_device *ced)
365 {
366 	struct clock_event_device *dev, *newdev = NULL;
367 
368 	list_for_each_entry(dev, &clockevent_devices, list) {
369 		if (dev == ced || !clockevent_state_detached(dev))
370 			continue;
371 
372 		if (!tick_check_replacement(newdev, dev))
373 			continue;
374 
375 		if (!try_module_get(dev->owner))
376 			continue;
377 
378 		if (newdev)
379 			module_put(newdev->owner);
380 		newdev = dev;
381 	}
382 	if (newdev) {
383 		tick_install_replacement(newdev);
384 		list_del_init(&ced->list);
385 	}
386 	return newdev ? 0 : -EBUSY;
387 }
388 
389 /*
390  * Called with clockevents_mutex and clockevents_lock held
391  */
392 static int __clockevents_try_unbind(struct clock_event_device *ced, int cpu)
393 {
394 	/* Fast track. Device is unused */
395 	if (clockevent_state_detached(ced)) {
396 		list_del_init(&ced->list);
397 		return 0;
398 	}
399 
400 	return ced == per_cpu(tick_cpu_device, cpu).evtdev ? -EAGAIN : -EBUSY;
401 }
402 
403 /*
404  * SMP function call to unbind a device
405  */
406 static void __clockevents_unbind(void *arg)
407 {
408 	struct ce_unbind *cu = arg;
409 	int res;
410 
411 	raw_spin_lock(&clockevents_lock);
412 	res = __clockevents_try_unbind(cu->ce, smp_processor_id());
413 	if (res == -EAGAIN)
414 		res = clockevents_replace(cu->ce);
415 	cu->res = res;
416 	raw_spin_unlock(&clockevents_lock);
417 }
418 
419 /*
420  * Issues smp function call to unbind a per cpu device. Called with
421  * clockevents_mutex held.
422  */
423 static int clockevents_unbind(struct clock_event_device *ced, int cpu)
424 {
425 	struct ce_unbind cu = { .ce = ced, .res = -ENODEV };
426 
427 	smp_call_function_single(cpu, __clockevents_unbind, &cu, 1);
428 	return cu.res;
429 }
430 
431 /*
432  * Unbind a clockevents device.
433  */
434 int clockevents_unbind_device(struct clock_event_device *ced, int cpu)
435 {
436 	int ret;
437 
438 	mutex_lock(&clockevents_mutex);
439 	ret = clockevents_unbind(ced, cpu);
440 	mutex_unlock(&clockevents_mutex);
441 	return ret;
442 }
443 EXPORT_SYMBOL_GPL(clockevents_unbind_device);
444 
445 /**
446  * clockevents_register_device - register a clock event device
447  * @dev:	device to register
448  */
449 void clockevents_register_device(struct clock_event_device *dev)
450 {
451 	unsigned long flags;
452 
453 	/* Initialize state to DETACHED */
454 	clockevent_set_state(dev, CLOCK_EVT_STATE_DETACHED);
455 
456 	if (!dev->cpumask) {
457 		WARN_ON(num_possible_cpus() > 1);
458 		dev->cpumask = cpumask_of(smp_processor_id());
459 	}
460 
461 	raw_spin_lock_irqsave(&clockevents_lock, flags);
462 
463 	list_add(&dev->list, &clockevent_devices);
464 	tick_check_new_device(dev);
465 	clockevents_notify_released();
466 
467 	raw_spin_unlock_irqrestore(&clockevents_lock, flags);
468 }
469 EXPORT_SYMBOL_GPL(clockevents_register_device);
470 
471 void clockevents_config(struct clock_event_device *dev, u32 freq)
472 {
473 	u64 sec;
474 
475 	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 	sec = dev->max_delta_ticks;
484 	do_div(sec, freq);
485 	if (!sec)
486 		sec = 1;
487 	else if (sec > 600 && dev->max_delta_ticks > UINT_MAX)
488 		sec = 600;
489 
490 	clockevents_calc_mult_shift(dev, freq, sec);
491 	dev->min_delta_ns = cev_delta2ns(dev->min_delta_ticks, dev, false);
492 	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 void clockevents_config_and_register(struct clock_event_device *dev,
505 				     u32 freq, unsigned long min_delta,
506 				     unsigned long max_delta)
507 {
508 	dev->min_delta_ticks = min_delta;
509 	dev->max_delta_ticks = max_delta;
510 	clockevents_config(dev, freq);
511 	clockevents_register_device(dev);
512 }
513 EXPORT_SYMBOL_GPL(clockevents_config_and_register);
514 
515 int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)
516 {
517 	clockevents_config(dev, freq);
518 
519 	if (clockevent_state_oneshot(dev))
520 		return clockevents_program_event(dev, dev->next_event, false);
521 
522 	if (clockevent_state_periodic(dev))
523 		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 int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
541 {
542 	unsigned long flags;
543 	int ret;
544 
545 	local_irq_save(flags);
546 	ret = tick_broadcast_update_freq(dev, freq);
547 	if (ret == -ENODEV)
548 		ret = __clockevents_update_freq(dev, freq);
549 	local_irq_restore(flags);
550 	return ret;
551 }
552 
553 /*
554  * Noop handler when we shut down an event device
555  */
556 void clockevents_handle_noop(struct clock_event_device *dev)
557 {
558 }
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 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 	if (old) {
576 		module_put(old->owner);
577 		clockevents_switch_state(old, CLOCK_EVT_STATE_DETACHED);
578 		list_del(&old->list);
579 		list_add(&old->list, &clockevents_released);
580 	}
581 
582 	if (new) {
583 		BUG_ON(!clockevent_state_detached(new));
584 		clockevents_shutdown(new);
585 	}
586 }
587 
588 /**
589  * clockevents_suspend - suspend clock devices
590  */
591 void clockevents_suspend(void)
592 {
593 	struct clock_event_device *dev;
594 
595 	list_for_each_entry_reverse(dev, &clockevent_devices, list)
596 		if (dev->suspend && !clockevent_state_detached(dev))
597 			dev->suspend(dev);
598 }
599 
600 /**
601  * clockevents_resume - resume clock devices
602  */
603 void clockevents_resume(void)
604 {
605 	struct clock_event_device *dev;
606 
607 	list_for_each_entry(dev, &clockevent_devices, list)
608 		if (dev->resume && !clockevent_state_detached(dev))
609 			dev->resume(dev);
610 }
611 
612 #ifdef CONFIG_HOTPLUG_CPU
613 /**
614  * tick_cleanup_dead_cpu - Cleanup the tick and clockevents of a dead cpu
615  */
616 void tick_cleanup_dead_cpu(int cpu)
617 {
618 	struct clock_event_device *dev, *tmp;
619 	unsigned long flags;
620 
621 	raw_spin_lock_irqsave(&clockevents_lock, flags);
622 
623 	tick_shutdown_broadcast_oneshot(cpu);
624 	tick_shutdown_broadcast(cpu);
625 	tick_shutdown(cpu);
626 	/*
627 	 * Unregister the clock event devices which were
628 	 * released from the users in the notify chain.
629 	 */
630 	list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
631 		list_del(&dev->list);
632 	/*
633 	 * Now check whether the CPU has left unused per cpu devices
634 	 */
635 	list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
636 		if (cpumask_test_cpu(cpu, dev->cpumask) &&
637 		    cpumask_weight(dev->cpumask) == 1 &&
638 		    !tick_is_broadcast_device(dev)) {
639 			BUG_ON(!clockevent_state_detached(dev));
640 			list_del(&dev->list);
641 		}
642 	}
643 	raw_spin_unlock_irqrestore(&clockevents_lock, flags);
644 }
645 #endif
646 
647 #ifdef CONFIG_SYSFS
648 struct bus_type clockevents_subsys = {
649 	.name		= "clockevents",
650 	.dev_name       = "clockevent",
651 };
652 
653 static DEFINE_PER_CPU(struct device, tick_percpu_dev);
654 static struct tick_device *tick_get_tick_dev(struct device *dev);
655 
656 static ssize_t sysfs_show_current_tick_dev(struct device *dev,
657 					   struct device_attribute *attr,
658 					   char *buf)
659 {
660 	struct tick_device *td;
661 	ssize_t count = 0;
662 
663 	raw_spin_lock_irq(&clockevents_lock);
664 	td = tick_get_tick_dev(dev);
665 	if (td && td->evtdev)
666 		count = snprintf(buf, PAGE_SIZE, "%s\n", td->evtdev->name);
667 	raw_spin_unlock_irq(&clockevents_lock);
668 	return count;
669 }
670 static DEVICE_ATTR(current_device, 0444, sysfs_show_current_tick_dev, NULL);
671 
672 /* We don't support the abomination of removable broadcast devices */
673 static ssize_t sysfs_unbind_tick_dev(struct device *dev,
674 				     struct device_attribute *attr,
675 				     const char *buf, size_t count)
676 {
677 	char name[CS_NAME_LEN];
678 	ssize_t ret = sysfs_get_uname(buf, name, count);
679 	struct clock_event_device *ce;
680 
681 	if (ret < 0)
682 		return ret;
683 
684 	ret = -ENODEV;
685 	mutex_lock(&clockevents_mutex);
686 	raw_spin_lock_irq(&clockevents_lock);
687 	list_for_each_entry(ce, &clockevent_devices, list) {
688 		if (!strcmp(ce->name, name)) {
689 			ret = __clockevents_try_unbind(ce, dev->id);
690 			break;
691 		}
692 	}
693 	raw_spin_unlock_irq(&clockevents_lock);
694 	/*
695 	 * We hold clockevents_mutex, so ce can't go away
696 	 */
697 	if (ret == -EAGAIN)
698 		ret = clockevents_unbind(ce, dev->id);
699 	mutex_unlock(&clockevents_mutex);
700 	return ret ? ret : count;
701 }
702 static DEVICE_ATTR(unbind_device, 0200, NULL, sysfs_unbind_tick_dev);
703 
704 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
705 static struct device tick_bc_dev = {
706 	.init_name	= "broadcast",
707 	.id		= 0,
708 	.bus		= &clockevents_subsys,
709 };
710 
711 static struct tick_device *tick_get_tick_dev(struct device *dev)
712 {
713 	return dev == &tick_bc_dev ? tick_get_broadcast_device() :
714 		&per_cpu(tick_cpu_device, dev->id);
715 }
716 
717 static __init int tick_broadcast_init_sysfs(void)
718 {
719 	int err = device_register(&tick_bc_dev);
720 
721 	if (!err)
722 		err = device_create_file(&tick_bc_dev, &dev_attr_current_device);
723 	return err;
724 }
725 #else
726 static struct tick_device *tick_get_tick_dev(struct device *dev)
727 {
728 	return &per_cpu(tick_cpu_device, dev->id);
729 }
730 static inline int tick_broadcast_init_sysfs(void) { return 0; }
731 #endif
732 
733 static int __init tick_init_sysfs(void)
734 {
735 	int cpu;
736 
737 	for_each_possible_cpu(cpu) {
738 		struct device *dev = &per_cpu(tick_percpu_dev, cpu);
739 		int err;
740 
741 		dev->id = cpu;
742 		dev->bus = &clockevents_subsys;
743 		err = device_register(dev);
744 		if (!err)
745 			err = device_create_file(dev, &dev_attr_current_device);
746 		if (!err)
747 			err = device_create_file(dev, &dev_attr_unbind_device);
748 		if (err)
749 			return err;
750 	}
751 	return tick_broadcast_init_sysfs();
752 }
753 
754 static int __init clockevents_init_sysfs(void)
755 {
756 	int err = subsys_system_register(&clockevents_subsys, NULL);
757 
758 	if (!err)
759 		err = tick_init_sysfs();
760 	return err;
761 }
762 device_initcall(clockevents_init_sysfs);
763 #endif /* SYSFS */
764