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 */
20static LIST_HEAD(clockevent_devices);
21static LIST_HEAD(clockevents_released);
22/* Protection for the above */
23static DEFINE_RAW_SPINLOCK(clockevents_lock);
24/* Protection for unbind operations */
25static DEFINE_MUTEX(clockevents_mutex);
26
27struct ce_unbind {
28	struct clock_event_device *ce;
29	int res;
30};
31
32static u64 cev_delta2ns(unsigned long latch, struct clock_event_device *evt,
33			bool ismax)
34{
35	u64 clc = (u64) latch << evt->shift;
36	u64 rnd;
37
38	if (WARN_ON(!evt->mult))
39		evt->mult = 1;
40	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	if ((clc >> evt->shift) != (u64)latch)
47		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	if ((~0ULL - clc > rnd) &&
69	    (!ismax || evt->mult <= (1ULL << evt->shift)))
70		clc += rnd;
71
72	do_div(clc, evt->mult);
73
74	/* Deltas less than 1usec are pointless noise */
75	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 */
85u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
86{
87	return cev_delta2ns(latch, evt, false);
88}
89EXPORT_SYMBOL_GPL(clockevent_delta2ns);
90
91static int __clockevents_switch_state(struct clock_event_device *dev,
92				      enum clock_event_state state)
93{
94	if (dev->features & CLOCK_EVT_FEAT_DUMMY)
95		return 0;
96
97	/* Transition with new state-specific callbacks */
98	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		if (dev->set_state_shutdown)
104			return dev->set_state_shutdown(dev);
105		return 0;
106
107	case CLOCK_EVT_STATE_PERIODIC:
108		/* Core internal bug */
109		if (!(dev->features & CLOCK_EVT_FEAT_PERIODIC))
110			return -ENOSYS;
111		if (dev->set_state_periodic)
112			return dev->set_state_periodic(dev);
113		return 0;
114
115	case CLOCK_EVT_STATE_ONESHOT:
116		/* Core internal bug */
117		if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
118			return -ENOSYS;
119		if (dev->set_state_oneshot)
120			return dev->set_state_oneshot(dev);
121		return 0;
122
123	case CLOCK_EVT_STATE_ONESHOT_STOPPED:
124		/* Core internal bug */
125		if (WARN_ONCE(!clockevent_state_oneshot(dev),
126			      "Current state: %d\n",
127			      clockevent_get_state(dev)))
128			return -EINVAL;
129
130		if (dev->set_state_oneshot_stopped)
131			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 */
147void clockevents_switch_state(struct clock_event_device *dev,
148			      enum clock_event_state state)
149{
150	if (clockevent_get_state(dev) != state) {
151		if (__clockevents_switch_state(dev, state))
152			return;
153
154		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		if (clockevent_state_oneshot(dev)) {
161			if (WARN_ON(!dev->mult))
162				dev->mult = 1;
163		}
164	}
165}
166
167/**
168 * clockevents_shutdown - shutdown the device and clear next_event
169 * @dev:	device to shutdown
170 */
171void clockevents_shutdown(struct clock_event_device *dev)
172{
173	clockevents_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
174	dev->next_event = KTIME_MAX;
175}
176
177/**
178 * clockevents_tick_resume -	Resume the tick device before using it again
179 * @dev:			device to resume
180 */
181int clockevents_tick_resume(struct clock_event_device *dev)
182{
183	int ret = 0;
184
185	if (dev->tick_resume)
186		ret = dev->tick_resume(dev);
187
188	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 */
202static 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 */
233static 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 */
272static int clockevents_program_min_delta(struct clock_event_device *dev)
273{
274	unsigned long long clc;
275	int64_t delta = 0;
276	int i;
277
278	for (i = 0; i < 10; i++) {
279		delta += dev->min_delta_ns;
280		dev->next_event = ktime_add_ns(ktime_get(), delta);
281
282		if (clockevent_state_shutdown(dev))
283			return 0;
284
285		dev->retries++;
286		clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
287		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 */
303int 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	if (WARN_ON_ONCE(expires < 0))
311		return -ETIME;
312
313	dev->next_event = expires;
314
315	if (clockevent_state_shutdown(dev))
316		return 0;
317
318	/* We must be in ONESHOT state here */
319	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	if (dev->features & CLOCK_EVT_FEAT_KTIME)
324		return dev->set_next_ktime(expires, dev);
325
326	delta = ktime_to_ns(ktime_sub(expires, ktime_get()));
327	if (delta <= 0)
328		return force ? clockevents_program_min_delta(dev) : -ETIME;
329
330	delta = min(delta, (int64_t) dev->max_delta_ns);
331	delta = max(delta, (int64_t) dev->min_delta_ns);
332
333	clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
334	rc = dev->set_next_event((unsigned long) clc, dev);
335
336	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 */
343static void clockevents_notify_released(void)
344{
345	struct clock_event_device *dev;
346
347	while (!list_empty(&clockevents_released)) {
348		dev = list_entry(clockevents_released.next,
349				 struct clock_event_device, list);
350		list_move(&dev->list, &clockevent_devices);
351		tick_check_new_device(dev);
352	}
353}
354
355/*
356 * Try to install a replacement clock event device
357 */
358static int clockevents_replace(struct clock_event_device *ced)
359{
360	struct clock_event_device *dev, *newdev = NULL;
361
362	list_for_each_entry(dev, &clockevent_devices, list) {
363		if (dev == ced || !clockevent_state_detached(dev))
364			continue;
365
366		if (!tick_check_replacement(newdev, dev))
367			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	if (newdev) {
377		tick_install_replacement(newdev);
378		list_del_init(&ced->list);
379	}
380	return newdev ? 0 : -EBUSY;
381}
382
383/*
384 * Called with clockevents_mutex and clockevents_lock held
385 */
386static int __clockevents_try_unbind(struct clock_event_device *ced, int cpu)
387{
388	/* Fast track. Device is unused */
389	if (clockevent_state_detached(ced)) {
390		list_del_init(&ced->list);
391		return 0;
392	}
393
394	return ced == per_cpu(tick_cpu_device, cpu).evtdev ? -EAGAIN : -EBUSY;
395}
396
397/*
398 * SMP function call to unbind a device
399 */
400static void __clockevents_unbind(void *arg)
401{
402	struct ce_unbind *cu = arg;
403	int res;
404
405	raw_spin_lock(&clockevents_lock);
406	res = __clockevents_try_unbind(cu->ce, smp_processor_id());
407	if (res == -EAGAIN)
408		res = clockevents_replace(cu->ce);
409	cu->res = res;
410	raw_spin_unlock(&clockevents_lock);
411}
412
413/*
414 * Issues smp function call to unbind a per cpu device. Called with
415 * clockevents_mutex held.
416 */
417static int clockevents_unbind(struct clock_event_device *ced, int cpu)
418{
419	struct ce_unbind cu = { .ce = ced, .res = -ENODEV };
420
421	smp_call_function_single(cpu, __clockevents_unbind, &cu, 1);
422	return cu.res;
423}
424
425/*
426 * Unbind a clockevents device.
427 */
428int clockevents_unbind_device(struct clock_event_device *ced, int cpu)
429{
430	int ret;
431
432	mutex_lock(&clockevents_mutex);
433	ret = clockevents_unbind(ced, cpu);
434	mutex_unlock(&clockevents_mutex);
435	return ret;
436}
437EXPORT_SYMBOL_GPL(clockevents_unbind_device);
438
439/**
440 * clockevents_register_device - register a clock event device
441 * @dev:	device to register
442 */
443void clockevents_register_device(struct clock_event_device *dev)
444{
445	unsigned long flags;
446
447	/* Initialize state to DETACHED */
448	clockevent_set_state(dev, CLOCK_EVT_STATE_DETACHED);
449
450	if (!dev->cpumask) {
451		WARN_ON(num_possible_cpus() > 1);
452		dev->cpumask = cpumask_of(smp_processor_id());
453	}
454
455	if (dev->cpumask == cpu_all_mask) {
456		WARN(1, "%s cpumask == cpu_all_mask, using cpu_possible_mask instead\n",
457		     dev->name);
458		dev->cpumask = cpu_possible_mask;
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}
469EXPORT_SYMBOL_GPL(clockevents_register_device);
470
471static 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 */
504void 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}
513EXPORT_SYMBOL_GPL(clockevents_config_and_register);
514
515int __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 */
540int 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 */
556void 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 */
568void 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_move(&old->list, &clockevents_released);
579	}
580
581	if (new) {
582		BUG_ON(!clockevent_state_detached(new));
583		clockevents_shutdown(new);
584	}
585}
586
587/**
588 * clockevents_suspend - suspend clock devices
589 */
590void clockevents_suspend(void)
591{
592	struct clock_event_device *dev;
593
594	list_for_each_entry_reverse(dev, &clockevent_devices, list)
595		if (dev->suspend && !clockevent_state_detached(dev))
596			dev->suspend(dev);
597}
598
599/**
600 * clockevents_resume - resume clock devices
601 */
602void clockevents_resume(void)
603{
604	struct clock_event_device *dev;
605
606	list_for_each_entry(dev, &clockevent_devices, list)
607		if (dev->resume && !clockevent_state_detached(dev))
608			dev->resume(dev);
609}
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 */
620void 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 */
632void 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
662static const struct bus_type clockevents_subsys = {
663	.name		= "clockevents",
664	.dev_name       = "clockevent",
665};
666
667static DEFINE_PER_CPU(struct device, tick_percpu_dev);
668static struct tick_device *tick_get_tick_dev(struct device *dev);
669
670static ssize_t current_device_show(struct device *dev,
671				   struct device_attribute *attr,
672				   char *buf)
673{
674	struct tick_device *td;
675	ssize_t count = 0;
676
677	raw_spin_lock_irq(&clockevents_lock);
678	td = tick_get_tick_dev(dev);
679	if (td && td->evtdev)
680		count = snprintf(buf, PAGE_SIZE, "%s\n", td->evtdev->name);
681	raw_spin_unlock_irq(&clockevents_lock);
682	return count;
683}
684static DEVICE_ATTR_RO(current_device);
685
686/* We don't support the abomination of removable broadcast devices */
687static 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	ssize_t ret = sysfs_get_uname(buf, name, count);
693	struct clock_event_device *ce = NULL, *iter;
694
695	if (ret < 0)
696		return ret;
697
698	ret = -ENODEV;
699	mutex_lock(&clockevents_mutex);
700	raw_spin_lock_irq(&clockevents_lock);
701	list_for_each_entry(iter, &clockevent_devices, list) {
702		if (!strcmp(iter->name, name)) {
703			ret = __clockevents_try_unbind(iter, dev->id);
704			ce = iter;
705			break;
706		}
707	}
708	raw_spin_unlock_irq(&clockevents_lock);
709	/*
710	 * We hold clockevents_mutex, so ce can't go away
711	 */
712	if (ret == -EAGAIN)
713		ret = clockevents_unbind(ce, dev->id);
714	mutex_unlock(&clockevents_mutex);
715	return ret ? ret : count;
716}
717static DEVICE_ATTR_WO(unbind_device);
718
719#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
720static struct device tick_bc_dev = {
721	.init_name	= "broadcast",
722	.id		= 0,
723	.bus		= &clockevents_subsys,
724};
725
726static 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
732static __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
741static struct tick_device *tick_get_tick_dev(struct device *dev)
742{
743	return &per_cpu(tick_cpu_device, dev->id);
744}
745static inline int tick_broadcast_init_sysfs(void) { return 0; }
746#endif
747
748static int __init tick_init_sysfs(void)
749{
750	int cpu;
751
752	for_each_possible_cpu(cpu) {
753		struct device *dev = &per_cpu(tick_percpu_dev, cpu);
754		int err;
755
756		dev->id = cpu;
757		dev->bus = &clockevents_subsys;
758		err = device_register(dev);
759		if (!err)
760			err = device_create_file(dev, &dev_attr_current_device);
761		if (!err)
762			err = device_create_file(dev, &dev_attr_unbind_device);
763		if (err)
764			return err;
765	}
766	return tick_broadcast_init_sysfs();
767}
768
769static int __init clockevents_init_sysfs(void)
770{
771	int err = subsys_system_register(&clockevents_subsys, NULL);
772
773	if (!err)
774		err = tick_init_sysfs();
775	return err;
776}
777device_initcall(clockevents_init_sysfs);
778#endif /* SYSFS */
779