1/*
  2 * linux/kernel/time/tick-common.c
  3 *
  4 * This file contains the base functions to manage periodic tick
  5 * related events.
  6 *
  7 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
  8 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
  9 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
 10 *
 11 * This code is licenced under the GPL version 2. For details see
 12 * kernel-base/COPYING.
 13 */
 14#include <linux/cpu.h>
 15#include <linux/err.h>
 16#include <linux/hrtimer.h>
 17#include <linux/interrupt.h>
 18#include <linux/percpu.h>
 19#include <linux/profile.h>
 20#include <linux/sched.h>
 21
 22#include <asm/irq_regs.h>
 23
 24#include "tick-internal.h"
 25
 26/*
 27 * Tick devices
 28 */
 29DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
 30/*
 31 * Tick next event: keeps track of the tick time
 32 */
 33ktime_t tick_next_period;
 34ktime_t tick_period;
 35int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT;
 36static DEFINE_RAW_SPINLOCK(tick_device_lock);
 37
 38/*
 39 * Debugging: see timer_list.c
 40 */
 41struct tick_device *tick_get_device(int cpu)
 42{
 43	return &per_cpu(tick_cpu_device, cpu);
 44}
 45
 46/**
 47 * tick_is_oneshot_available - check for a oneshot capable event device
 48 */
 49int tick_is_oneshot_available(void)
 50{
 51	struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
 52
 53	if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT))
 54		return 0;
 55	if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
 56		return 1;
 57	return tick_broadcast_oneshot_available();
 58}
 59
 60/*
 61 * Periodic tick
 62 */
 63static void tick_periodic(int cpu)
 64{
 65	if (tick_do_timer_cpu == cpu) {
 66		write_seqlock(&xtime_lock);
 67
 68		/* Keep track of the next tick event */
 69		tick_next_period = ktime_add(tick_next_period, tick_period);
 70
 71		do_timer(1);
 72		write_sequnlock(&xtime_lock);
 73	}
 74
 75	update_process_times(user_mode(get_irq_regs()));
 76	profile_tick(CPU_PROFILING);
 77}
 78
 79/*
 80 * Event handler for periodic ticks
 81 */
 82void tick_handle_periodic(struct clock_event_device *dev)
 83{
 84	int cpu = smp_processor_id();
 85	ktime_t next;
 86
 87	tick_periodic(cpu);
 88
 89	if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
 90		return;
 91	/*
 92	 * Setup the next period for devices, which do not have
 93	 * periodic mode:
 94	 */
 95	next = ktime_add(dev->next_event, tick_period);
 96	for (;;) {
 97		if (!clockevents_program_event(dev, next, false))
 98			return;
 99		/*
100		 * Have to be careful here. If we're in oneshot mode,
101		 * before we call tick_periodic() in a loop, we need
102		 * to be sure we're using a real hardware clocksource.
103		 * Otherwise we could get trapped in an infinite
104		 * loop, as the tick_periodic() increments jiffies,
105		 * when then will increment time, posibly causing
106		 * the loop to trigger again and again.
107		 */
108		if (timekeeping_valid_for_hres())
109			tick_periodic(cpu);
110		next = ktime_add(next, tick_period);
111	}
112}
113
114/*
115 * Setup the device for a periodic tick
116 */
117void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
118{
119	tick_set_periodic_handler(dev, broadcast);
120
121	/* Broadcast setup ? */
122	if (!tick_device_is_functional(dev))
123		return;
124
125	if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) &&
126	    !tick_broadcast_oneshot_active()) {
127		clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC);
128	} else {
129		unsigned long seq;
130		ktime_t next;
131
132		do {
133			seq = read_seqbegin(&xtime_lock);
134			next = tick_next_period;
135		} while (read_seqretry(&xtime_lock, seq));
136
137		clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
138
139		for (;;) {
140			if (!clockevents_program_event(dev, next, false))
141				return;
142			next = ktime_add(next, tick_period);
143		}
144	}
145}
146
147/*
148 * Setup the tick device
149 */
150static void tick_setup_device(struct tick_device *td,
151			      struct clock_event_device *newdev, int cpu,
152			      const struct cpumask *cpumask)
153{
154	ktime_t next_event;
155	void (*handler)(struct clock_event_device *) = NULL;
156
157	/*
158	 * First device setup ?
159	 */
160	if (!td->evtdev) {
161		/*
162		 * If no cpu took the do_timer update, assign it to
163		 * this cpu:
164		 */
165		if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {
166			tick_do_timer_cpu = cpu;
167			tick_next_period = ktime_get();
168			tick_period = ktime_set(0, NSEC_PER_SEC / HZ);
169		}
170
171		/*
172		 * Startup in periodic mode first.
173		 */
174		td->mode = TICKDEV_MODE_PERIODIC;
175	} else {
176		handler = td->evtdev->event_handler;
177		next_event = td->evtdev->next_event;
178		td->evtdev->event_handler = clockevents_handle_noop;
179	}
180
181	td->evtdev = newdev;
182
183	/*
184	 * When the device is not per cpu, pin the interrupt to the
185	 * current cpu:
186	 */
187	if (!cpumask_equal(newdev->cpumask, cpumask))
188		irq_set_affinity(newdev->irq, cpumask);
189
190	/*
191	 * When global broadcasting is active, check if the current
192	 * device is registered as a placeholder for broadcast mode.
193	 * This allows us to handle this x86 misfeature in a generic
194	 * way.
195	 */
196	if (tick_device_uses_broadcast(newdev, cpu))
197		return;
198
199	if (td->mode == TICKDEV_MODE_PERIODIC)
200		tick_setup_periodic(newdev, 0);
201	else
202		tick_setup_oneshot(newdev, handler, next_event);
203}
204
205/*
206 * Check, if the new registered device should be used.
207 */
208static int tick_check_new_device(struct clock_event_device *newdev)
209{
210	struct clock_event_device *curdev;
211	struct tick_device *td;
212	int cpu, ret = NOTIFY_OK;
213	unsigned long flags;
214
215	raw_spin_lock_irqsave(&tick_device_lock, flags);
216
217	cpu = smp_processor_id();
218	if (!cpumask_test_cpu(cpu, newdev->cpumask))
219		goto out_bc;
220
221	td = &per_cpu(tick_cpu_device, cpu);
222	curdev = td->evtdev;
223
224	/* cpu local device ? */
225	if (!cpumask_equal(newdev->cpumask, cpumask_of(cpu))) {
226
227		/*
228		 * If the cpu affinity of the device interrupt can not
229		 * be set, ignore it.
230		 */
231		if (!irq_can_set_affinity(newdev->irq))
232			goto out_bc;
233
234		/*
235		 * If we have a cpu local device already, do not replace it
236		 * by a non cpu local device
237		 */
238		if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu)))
239			goto out_bc;
240	}
241
242	/*
243	 * If we have an active device, then check the rating and the oneshot
244	 * feature.
245	 */
246	if (curdev) {
247		/*
248		 * Prefer one shot capable devices !
249		 */
250		if ((curdev->features & CLOCK_EVT_FEAT_ONESHOT) &&
251		    !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
252			goto out_bc;
253		/*
254		 * Check the rating
255		 */
256		if (curdev->rating >= newdev->rating)
257			goto out_bc;
258	}
259
260	/*
261	 * Replace the eventually existing device by the new
262	 * device. If the current device is the broadcast device, do
263	 * not give it back to the clockevents layer !
264	 */
265	if (tick_is_broadcast_device(curdev)) {
266		clockevents_shutdown(curdev);
267		curdev = NULL;
268	}
269	clockevents_exchange_device(curdev, newdev);
270	tick_setup_device(td, newdev, cpu, cpumask_of(cpu));
271	if (newdev->features & CLOCK_EVT_FEAT_ONESHOT)
272		tick_oneshot_notify();
273
274	raw_spin_unlock_irqrestore(&tick_device_lock, flags);
275	return NOTIFY_STOP;
276
277out_bc:
278	/*
279	 * Can the new device be used as a broadcast device ?
280	 */
281	if (tick_check_broadcast_device(newdev))
282		ret = NOTIFY_STOP;
283
284	raw_spin_unlock_irqrestore(&tick_device_lock, flags);
285
286	return ret;
287}
288
289/*
290 * Transfer the do_timer job away from a dying cpu.
291 *
292 * Called with interrupts disabled.
293 */
294static void tick_handover_do_timer(int *cpup)
295{
296	if (*cpup == tick_do_timer_cpu) {
297		int cpu = cpumask_first(cpu_online_mask);
298
299		tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu :
300			TICK_DO_TIMER_NONE;
301	}
302}
303
304/*
305 * Shutdown an event device on a given cpu:
306 *
307 * This is called on a life CPU, when a CPU is dead. So we cannot
308 * access the hardware device itself.
309 * We just set the mode and remove it from the lists.
310 */
311static void tick_shutdown(unsigned int *cpup)
312{
313	struct tick_device *td = &per_cpu(tick_cpu_device, *cpup);
314	struct clock_event_device *dev = td->evtdev;
315	unsigned long flags;
316
317	raw_spin_lock_irqsave(&tick_device_lock, flags);
318	td->mode = TICKDEV_MODE_PERIODIC;
319	if (dev) {
320		/*
321		 * Prevent that the clock events layer tries to call
322		 * the set mode function!
323		 */
324		dev->mode = CLOCK_EVT_MODE_UNUSED;
325		clockevents_exchange_device(dev, NULL);
326		td->evtdev = NULL;
327	}
328	raw_spin_unlock_irqrestore(&tick_device_lock, flags);
329}
330
331static void tick_suspend(void)
332{
333	struct tick_device *td = &__get_cpu_var(tick_cpu_device);
334	unsigned long flags;
335
336	raw_spin_lock_irqsave(&tick_device_lock, flags);
337	clockevents_shutdown(td->evtdev);
338	raw_spin_unlock_irqrestore(&tick_device_lock, flags);
339}
340
341static void tick_resume(void)
342{
343	struct tick_device *td = &__get_cpu_var(tick_cpu_device);
344	unsigned long flags;
345	int broadcast = tick_resume_broadcast();
346
347	raw_spin_lock_irqsave(&tick_device_lock, flags);
348	clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_RESUME);
349
350	if (!broadcast) {
351		if (td->mode == TICKDEV_MODE_PERIODIC)
352			tick_setup_periodic(td->evtdev, 0);
353		else
354			tick_resume_oneshot();
355	}
356	raw_spin_unlock_irqrestore(&tick_device_lock, flags);
357}
358
359/*
360 * Notification about clock event devices
361 */
362static int tick_notify(struct notifier_block *nb, unsigned long reason,
363			       void *dev)
364{
365	switch (reason) {
366
367	case CLOCK_EVT_NOTIFY_ADD:
368		return tick_check_new_device(dev);
369
370	case CLOCK_EVT_NOTIFY_BROADCAST_ON:
371	case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
372	case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
373		tick_broadcast_on_off(reason, dev);
374		break;
375
376	case CLOCK_EVT_NOTIFY_BROADCAST_ENTER:
377	case CLOCK_EVT_NOTIFY_BROADCAST_EXIT:
378		tick_broadcast_oneshot_control(reason);
379		break;
380
381	case CLOCK_EVT_NOTIFY_CPU_DYING:
382		tick_handover_do_timer(dev);
383		break;
384
385	case CLOCK_EVT_NOTIFY_CPU_DEAD:
386		tick_shutdown_broadcast_oneshot(dev);
387		tick_shutdown_broadcast(dev);
388		tick_shutdown(dev);
389		break;
390
391	case CLOCK_EVT_NOTIFY_SUSPEND:
392		tick_suspend();
393		tick_suspend_broadcast();
394		break;
395
396	case CLOCK_EVT_NOTIFY_RESUME:
397		tick_resume();
398		break;
399
400	default:
401		break;
402	}
403
404	return NOTIFY_OK;
405}
406
407static struct notifier_block tick_notifier = {
408	.notifier_call = tick_notify,
409};
410
411/**
412 * tick_init - initialize the tick control
413 *
414 * Register the notifier with the clockevents framework
415 */
416void __init tick_init(void)
417{
418	clockevents_register_notifier(&tick_notifier);
419}

  1/*
  2 * linux/kernel/time/tick-common.c
  3 *
  4 * This file contains the base functions to manage periodic tick
  5 * related events.
  6 *
  7 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
  8 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
  9 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
 10 *
 11 * This code is licenced under the GPL version 2. For details see
 12 * kernel-base/COPYING.
 13 */
 14#include <linux/cpu.h>
 15#include <linux/err.h>
 16#include <linux/hrtimer.h>
 17#include <linux/interrupt.h>
 18#include <linux/percpu.h>
 19#include <linux/profile.h>
 20#include <linux/sched.h>
 21
 22#include <asm/irq_regs.h>
 23
 24#include "tick-internal.h"
 25
 26/*
 27 * Tick devices
 28 */
 29DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
 30/*
 31 * Tick next event: keeps track of the tick time
 32 */
 33ktime_t tick_next_period;
 34ktime_t tick_period;
 35int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT;
 36static DEFINE_RAW_SPINLOCK(tick_device_lock);
 37
 38/*
 39 * Debugging: see timer_list.c
 40 */
 41struct tick_device *tick_get_device(int cpu)
 42{
 43	return &per_cpu(tick_cpu_device, cpu);
 44}
 45
 46/**
 47 * tick_is_oneshot_available - check for a oneshot capable event device
 48 */
 49int tick_is_oneshot_available(void)
 50{
 51	struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
 52
 53	if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT))
 54		return 0;
 55	if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
 56		return 1;
 57	return tick_broadcast_oneshot_available();
 58}
 59
 60/*
 61 * Periodic tick
 62 */
 63static void tick_periodic(int cpu)
 64{
 65	if (tick_do_timer_cpu == cpu) {
 66		write_seqlock(&xtime_lock);
 67
 68		/* Keep track of the next tick event */
 69		tick_next_period = ktime_add(tick_next_period, tick_period);
 70
 71		do_timer(1);
 72		write_sequnlock(&xtime_lock);
 73	}
 74
 75	update_process_times(user_mode(get_irq_regs()));
 76	profile_tick(CPU_PROFILING);
 77}
 78
 79/*
 80 * Event handler for periodic ticks
 81 */
 82void tick_handle_periodic(struct clock_event_device *dev)
 83{
 84	int cpu = smp_processor_id();
 85	ktime_t next;
 86
 87	tick_periodic(cpu);
 88
 89	if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
 90		return;
 91	/*
 92	 * Setup the next period for devices, which do not have
 93	 * periodic mode:
 94	 */
 95	next = ktime_add(dev->next_event, tick_period);
 96	for (;;) {
 97		if (!clockevents_program_event(dev, next, ktime_get()))
 98			return;
 99		/*
100		 * Have to be careful here. If we're in oneshot mode,
101		 * before we call tick_periodic() in a loop, we need
102		 * to be sure we're using a real hardware clocksource.
103		 * Otherwise we could get trapped in an infinite
104		 * loop, as the tick_periodic() increments jiffies,
105		 * when then will increment time, posibly causing
106		 * the loop to trigger again and again.
107		 */
108		if (timekeeping_valid_for_hres())
109			tick_periodic(cpu);
110		next = ktime_add(next, tick_period);
111	}
112}
113
114/*
115 * Setup the device for a periodic tick
116 */
117void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
118{
119	tick_set_periodic_handler(dev, broadcast);
120
121	/* Broadcast setup ? */
122	if (!tick_device_is_functional(dev))
123		return;
124
125	if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) &&
126	    !tick_broadcast_oneshot_active()) {
127		clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC);
128	} else {
129		unsigned long seq;
130		ktime_t next;
131
132		do {
133			seq = read_seqbegin(&xtime_lock);
134			next = tick_next_period;
135		} while (read_seqretry(&xtime_lock, seq));
136
137		clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
138
139		for (;;) {
140			if (!clockevents_program_event(dev, next, ktime_get()))
141				return;
142			next = ktime_add(next, tick_period);
143		}
144	}
145}
146
147/*
148 * Setup the tick device
149 */
150static void tick_setup_device(struct tick_device *td,
151			      struct clock_event_device *newdev, int cpu,
152			      const struct cpumask *cpumask)
153{
154	ktime_t next_event;
155	void (*handler)(struct clock_event_device *) = NULL;
156
157	/*
158	 * First device setup ?
159	 */
160	if (!td->evtdev) {
161		/*
162		 * If no cpu took the do_timer update, assign it to
163		 * this cpu:
164		 */
165		if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {
166			tick_do_timer_cpu = cpu;
167			tick_next_period = ktime_get();
168			tick_period = ktime_set(0, NSEC_PER_SEC / HZ);
169		}
170
171		/*
172		 * Startup in periodic mode first.
173		 */
174		td->mode = TICKDEV_MODE_PERIODIC;
175	} else {
176		handler = td->evtdev->event_handler;
177		next_event = td->evtdev->next_event;
178		td->evtdev->event_handler = clockevents_handle_noop;
179	}
180
181	td->evtdev = newdev;
182
183	/*
184	 * When the device is not per cpu, pin the interrupt to the
185	 * current cpu:
186	 */
187	if (!cpumask_equal(newdev->cpumask, cpumask))
188		irq_set_affinity(newdev->irq, cpumask);
189
190	/*
191	 * When global broadcasting is active, check if the current
192	 * device is registered as a placeholder for broadcast mode.
193	 * This allows us to handle this x86 misfeature in a generic
194	 * way.
195	 */
196	if (tick_device_uses_broadcast(newdev, cpu))
197		return;
198
199	if (td->mode == TICKDEV_MODE_PERIODIC)
200		tick_setup_periodic(newdev, 0);
201	else
202		tick_setup_oneshot(newdev, handler, next_event);
203}
204
205/*
206 * Check, if the new registered device should be used.
207 */
208static int tick_check_new_device(struct clock_event_device *newdev)
209{
210	struct clock_event_device *curdev;
211	struct tick_device *td;
212	int cpu, ret = NOTIFY_OK;
213	unsigned long flags;
214
215	raw_spin_lock_irqsave(&tick_device_lock, flags);
216
217	cpu = smp_processor_id();
218	if (!cpumask_test_cpu(cpu, newdev->cpumask))
219		goto out_bc;
220
221	td = &per_cpu(tick_cpu_device, cpu);
222	curdev = td->evtdev;
223
224	/* cpu local device ? */
225	if (!cpumask_equal(newdev->cpumask, cpumask_of(cpu))) {
226
227		/*
228		 * If the cpu affinity of the device interrupt can not
229		 * be set, ignore it.
230		 */
231		if (!irq_can_set_affinity(newdev->irq))
232			goto out_bc;
233
234		/*
235		 * If we have a cpu local device already, do not replace it
236		 * by a non cpu local device
237		 */
238		if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu)))
239			goto out_bc;
240	}
241
242	/*
243	 * If we have an active device, then check the rating and the oneshot
244	 * feature.
245	 */
246	if (curdev) {
247		/*
248		 * Prefer one shot capable devices !
249		 */
250		if ((curdev->features & CLOCK_EVT_FEAT_ONESHOT) &&
251		    !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
252			goto out_bc;
253		/*
254		 * Check the rating
255		 */
256		if (curdev->rating >= newdev->rating)
257			goto out_bc;
258	}
259
260	/*
261	 * Replace the eventually existing device by the new
262	 * device. If the current device is the broadcast device, do
263	 * not give it back to the clockevents layer !
264	 */
265	if (tick_is_broadcast_device(curdev)) {
266		clockevents_shutdown(curdev);
267		curdev = NULL;
268	}
269	clockevents_exchange_device(curdev, newdev);
270	tick_setup_device(td, newdev, cpu, cpumask_of(cpu));
271	if (newdev->features & CLOCK_EVT_FEAT_ONESHOT)
272		tick_oneshot_notify();
273
274	raw_spin_unlock_irqrestore(&tick_device_lock, flags);
275	return NOTIFY_STOP;
276
277out_bc:
278	/*
279	 * Can the new device be used as a broadcast device ?
280	 */
281	if (tick_check_broadcast_device(newdev))
282		ret = NOTIFY_STOP;
283
284	raw_spin_unlock_irqrestore(&tick_device_lock, flags);
285
286	return ret;
287}
288
289/*
290 * Transfer the do_timer job away from a dying cpu.
291 *
292 * Called with interrupts disabled.
293 */
294static void tick_handover_do_timer(int *cpup)
295{
296	if (*cpup == tick_do_timer_cpu) {
297		int cpu = cpumask_first(cpu_online_mask);
298
299		tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu :
300			TICK_DO_TIMER_NONE;
301	}
302}
303
304/*
305 * Shutdown an event device on a given cpu:
306 *
307 * This is called on a life CPU, when a CPU is dead. So we cannot
308 * access the hardware device itself.
309 * We just set the mode and remove it from the lists.
310 */
311static void tick_shutdown(unsigned int *cpup)
312{
313	struct tick_device *td = &per_cpu(tick_cpu_device, *cpup);
314	struct clock_event_device *dev = td->evtdev;
315	unsigned long flags;
316
317	raw_spin_lock_irqsave(&tick_device_lock, flags);
318	td->mode = TICKDEV_MODE_PERIODIC;
319	if (dev) {
320		/*
321		 * Prevent that the clock events layer tries to call
322		 * the set mode function!
323		 */
324		dev->mode = CLOCK_EVT_MODE_UNUSED;
325		clockevents_exchange_device(dev, NULL);
326		td->evtdev = NULL;
327	}
328	raw_spin_unlock_irqrestore(&tick_device_lock, flags);
329}
330
331static void tick_suspend(void)
332{
333	struct tick_device *td = &__get_cpu_var(tick_cpu_device);
334	unsigned long flags;
335
336	raw_spin_lock_irqsave(&tick_device_lock, flags);
337	clockevents_shutdown(td->evtdev);
338	raw_spin_unlock_irqrestore(&tick_device_lock, flags);
339}
340
341static void tick_resume(void)
342{
343	struct tick_device *td = &__get_cpu_var(tick_cpu_device);
344	unsigned long flags;
345	int broadcast = tick_resume_broadcast();
346
347	raw_spin_lock_irqsave(&tick_device_lock, flags);
348	clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_RESUME);
349
350	if (!broadcast) {
351		if (td->mode == TICKDEV_MODE_PERIODIC)
352			tick_setup_periodic(td->evtdev, 0);
353		else
354			tick_resume_oneshot();
355	}
356	raw_spin_unlock_irqrestore(&tick_device_lock, flags);
357}
358
359/*
360 * Notification about clock event devices
361 */
362static int tick_notify(struct notifier_block *nb, unsigned long reason,
363			       void *dev)
364{
365	switch (reason) {
366
367	case CLOCK_EVT_NOTIFY_ADD:
368		return tick_check_new_device(dev);
369
370	case CLOCK_EVT_NOTIFY_BROADCAST_ON:
371	case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
372	case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
373		tick_broadcast_on_off(reason, dev);
374		break;
375
376	case CLOCK_EVT_NOTIFY_BROADCAST_ENTER:
377	case CLOCK_EVT_NOTIFY_BROADCAST_EXIT:
378		tick_broadcast_oneshot_control(reason);
379		break;
380
381	case CLOCK_EVT_NOTIFY_CPU_DYING:
382		tick_handover_do_timer(dev);
383		break;
384
385	case CLOCK_EVT_NOTIFY_CPU_DEAD:
386		tick_shutdown_broadcast_oneshot(dev);
387		tick_shutdown_broadcast(dev);
388		tick_shutdown(dev);
389		break;
390
391	case CLOCK_EVT_NOTIFY_SUSPEND:
392		tick_suspend();
393		tick_suspend_broadcast();
394		break;
395
396	case CLOCK_EVT_NOTIFY_RESUME:
397		tick_resume();
398		break;
399
400	default:
401		break;
402	}
403
404	return NOTIFY_OK;
405}
406
407static struct notifier_block tick_notifier = {
408	.notifier_call = tick_notify,
409};
410
411/**
412 * tick_init - initialize the tick control
413 *
414 * Register the notifier with the clockevents framework
415 */
416void __init tick_init(void)
417{
418	clockevents_register_notifier(&tick_notifier);
419}