kernel/time/tick-broadcast.c - linux - Git at Google

 /*
  * linux/kernel/time/tick-broadcast.c
  *
  * This file contains functions which emulate a local clock-event
  * device via a broadcast event source.
  *
  * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
  * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
  * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
  *
  * This code is licenced under the GPL version 2. For details see
  * kernel-base/COPYING.
  */
 #include <linux/cpu.h>
 #include <linux/err.h>
 #include <linux/hrtimer.h>
 #include <linux/interrupt.h>
 #include <linux/percpu.h>
 #include <linux/profile.h>
 #include <linux/sched.h>
 #include <linux/tick.h>

 #include "tick-internal.h"

 /*
  * Broadcast support for broken x86 hardware, where the local apic
  * timer stops in C3 state.
  */

 static struct tick_device tick_broadcast_device;
 /* FIXME: Use cpumask_var_t. */
 static DECLARE_BITMAP(tick_broadcast_mask, NR_CPUS);
 static DECLARE_BITMAP(tmpmask, NR_CPUS);
 static DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
 static int tick_broadcast_force;

 #ifdef CONFIG_TICK_ONESHOT
 static void tick_broadcast_clear_oneshot(int cpu);
 #else
 static inline void tick_broadcast_clear_oneshot(int cpu) { }
 #endif

 /*
  * Debugging: see timer_list.c
  */
 struct tick_device *tick_get_broadcast_device(void)
 {
 	return &tick_broadcast_device;
 }

 struct cpumask *tick_get_broadcast_mask(void)
 {
 	return to_cpumask(tick_broadcast_mask);
 }

 /*
  * Start the device in periodic mode
  */
 static void tick_broadcast_start_periodic(struct clock_event_device *bc)
 {
 	if (bc)
 		tick_setup_periodic(bc, 1);
 }

 /*
  * Check, if the device can be utilized as broadcast device:
  */
 int tick_check_broadcast_device(struct clock_event_device *dev)
 {
 	if ((tick_broadcast_device.evtdev &&
 	     tick_broadcast_device.evtdev->rating >= dev->rating) ||
 	     (dev->features & CLOCK_EVT_FEAT_C3STOP))
 		return 0;

 	clockevents_exchange_device(NULL, dev);
 	tick_broadcast_device.evtdev = dev;
 	if (!cpumask_empty(tick_get_broadcast_mask()))
 		tick_broadcast_start_periodic(dev);
 	return 1;
 }

 /*
  * Check, if the device is the broadcast device
  */
 int tick_is_broadcast_device(struct clock_event_device *dev)
 {
 	return (dev && tick_broadcast_device.evtdev == dev);
 }

 /*
  * Check, if the device is disfunctional and a place holder, which
  * needs to be handled by the broadcast device.
  */
 int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
 {
 	unsigned long flags;
 	int ret = 0;

 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

 	/*
 	 * Devices might be registered with both periodic and oneshot
 	 * mode disabled. This signals, that the device needs to be
 	 * operated from the broadcast device and is a placeholder for
 	 * the cpu local device.
 	 */
 	if (!tick_device_is_functional(dev)) {
 		dev->event_handler = tick_handle_periodic;
 		cpumask_set_cpu(cpu, tick_get_broadcast_mask());
 		tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
 		ret = 1;
 	} else {
 		/*
 		 * When the new device is not affected by the stop
 		 * feature and the cpu is marked in the broadcast mask
 		 * then clear the broadcast bit.
 		 */
 		if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) {
 			int cpu = smp_processor_id();

 			cpumask_clear_cpu(cpu, tick_get_broadcast_mask());
 			tick_broadcast_clear_oneshot(cpu);
 		}
 	}
 	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 	return ret;
 }

 /*
  * Broadcast the event to the cpus, which are set in the mask (mangled).
  */
 static void tick_do_broadcast(struct cpumask *mask)
 {
 	int cpu = smp_processor_id();
 	struct tick_device *td;

 	/*
 	 * Check, if the current cpu is in the mask
 	 */
 	if (cpumask_test_cpu(cpu, mask)) {
 		cpumask_clear_cpu(cpu, mask);
 		td = &per_cpu(tick_cpu_device, cpu);
 		td->evtdev->event_handler(td->evtdev);
 	}

 	if (!cpumask_empty(mask)) {
 		/*
 		 * It might be necessary to actually check whether the devices
 		 * have different broadcast functions. For now, just use the
 		 * one of the first device. This works as long as we have this
 		 * misfeature only on x86 (lapic)
 		 */
 		td = &per_cpu(tick_cpu_device, cpumask_first(mask));
 		td->evtdev->broadcast(mask);
 	}
 }

 /*
  * Periodic broadcast:
  * - invoke the broadcast handlers
  */
 static void tick_do_periodic_broadcast(void)
 {
 	raw_spin_lock(&tick_broadcast_lock);

 	cpumask_and(to_cpumask(tmpmask),
 		    cpu_online_mask, tick_get_broadcast_mask());
 	tick_do_broadcast(to_cpumask(tmpmask));

 	raw_spin_unlock(&tick_broadcast_lock);
 }

 /*
  * Event handler for periodic broadcast ticks
  */
 static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
 {
 	ktime_t next;

 	tick_do_periodic_broadcast();

 	/*
 	 * The device is in periodic mode. No reprogramming necessary:
 	 */
 	if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
 		return;

 	/*
 	 * Setup the next period for devices, which do not have
 	 * periodic mode. We read dev->next_event first and add to it
 	 * when the event alrady expired. clockevents_program_event()
 	 * sets dev->next_event only when the event is really
 	 * programmed to the device.
 	 */
 	for (next = dev->next_event; ;) {
 		next = ktime_add(next, tick_period);

 		if (!clockevents_program_event(dev, next, ktime_get()))
 			return;
 		tick_do_periodic_broadcast();
 	}
 }

 /*
  * Powerstate information: The system enters/leaves a state, where
  * affected devices might stop
  */
 static void tick_do_broadcast_on_off(unsigned long *reason)
 {
 	struct clock_event_device *bc, *dev;
 	struct tick_device *td;
 	unsigned long flags;
 	int cpu, bc_stopped;

 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

 	cpu = smp_processor_id();
 	td = &per_cpu(tick_cpu_device, cpu);
 	dev = td->evtdev;
 	bc = tick_broadcast_device.evtdev;

 	/*
 	 * Is the device not affected by the powerstate ?
 	 */
 	if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
 		goto out;

 	if (!tick_device_is_functional(dev))
 		goto out;

 	bc_stopped = cpumask_empty(tick_get_broadcast_mask());

 	switch (*reason) {
 	case CLOCK_EVT_NOTIFY_BROADCAST_ON:
 	case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
 		if (!cpumask_test_cpu(cpu, tick_get_broadcast_mask())) {
 			cpumask_set_cpu(cpu, tick_get_broadcast_mask());
 			if (tick_broadcast_device.mode ==
 			    TICKDEV_MODE_PERIODIC)
 				clockevents_shutdown(dev);
 		}
 		if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_FORCE)
 			tick_broadcast_force = 1;
 		break;
 	case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
 		if (!tick_broadcast_force &&
 		    cpumask_test_cpu(cpu, tick_get_broadcast_mask())) {
 			cpumask_clear_cpu(cpu, tick_get_broadcast_mask());
 			if (tick_broadcast_device.mode ==
 			    TICKDEV_MODE_PERIODIC)
 				tick_setup_periodic(dev, 0);
 		}
 		break;
 	}

 	if (cpumask_empty(tick_get_broadcast_mask())) {
 		if (!bc_stopped)
 			clockevents_shutdown(bc);
 	} else if (bc_stopped) {
 		if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
 			tick_broadcast_start_periodic(bc);
 		else
 			tick_broadcast_setup_oneshot(bc);
 	}
 out:
 	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 }

 /*
  * Powerstate information: The system enters/leaves a state, where
  * affected devices might stop.
  */
 void tick_broadcast_on_off(unsigned long reason, int *oncpu)
 {
 	if (!cpumask_test_cpu(*oncpu, cpu_online_mask))
 		printk(KERN_ERR "tick-broadcast: ignoring broadcast for "
 		       "offline CPU #%d\n", *oncpu);
 	else
 		tick_do_broadcast_on_off(&reason);
 }

 /*
  * Set the periodic handler depending on broadcast on/off
  */
 void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
 {
 	if (!broadcast)
 		dev->event_handler = tick_handle_periodic;
 	else
 		dev->event_handler = tick_handle_periodic_broadcast;
 }

 /*
  * Remove a CPU from broadcasting
  */
 void tick_shutdown_broadcast(unsigned int *cpup)
 {
 	struct clock_event_device *bc;
 	unsigned long flags;
 	unsigned int cpu = *cpup;

 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

 	bc = tick_broadcast_device.evtdev;
 	cpumask_clear_cpu(cpu, tick_get_broadcast_mask());

 	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
 		if (bc && cpumask_empty(tick_get_broadcast_mask()))
 			clockevents_shutdown(bc);
 	}

 	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 }

 void tick_suspend_broadcast(void)
 {
 	struct clock_event_device *bc;
 	unsigned long flags;

 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

 	bc = tick_broadcast_device.evtdev;
 	if (bc)
 		clockevents_shutdown(bc);

 	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 }

 int tick_resume_broadcast(void)
 {
 	struct clock_event_device *bc;
 	unsigned long flags;
 	int broadcast = 0;

 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

 	bc = tick_broadcast_device.evtdev;

 	if (bc) {
 		clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);

 		switch (tick_broadcast_device.mode) {
 		case TICKDEV_MODE_PERIODIC:
 			if (!cpumask_empty(tick_get_broadcast_mask()))
 				tick_broadcast_start_periodic(bc);
 			broadcast = cpumask_test_cpu(smp_processor_id(),
 						     tick_get_broadcast_mask());
 			break;
 		case TICKDEV_MODE_ONESHOT:
 			broadcast = tick_resume_broadcast_oneshot(bc);
 			break;
 		}
 	}
 	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);

 	return broadcast;
 }


 #ifdef CONFIG_TICK_ONESHOT

 /* FIXME: use cpumask_var_t. */
 static DECLARE_BITMAP(tick_broadcast_oneshot_mask, NR_CPUS);

 /*
  * Exposed for debugging: see timer_list.c
  */
 struct cpumask *tick_get_broadcast_oneshot_mask(void)
 {
 	return to_cpumask(tick_broadcast_oneshot_mask);
 }

 static int tick_broadcast_set_event(ktime_t expires, int force)
 {
 	struct clock_event_device *bc = tick_broadcast_device.evtdev;

 	return tick_dev_program_event(bc, expires, force);
 }

 int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
 {
 	clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
 	return 0;
 }

 /*
  * Called from irq_enter() when idle was interrupted to reenable the
  * per cpu device.
  */
 void tick_check_oneshot_broadcast(int cpu)
 {
 	if (cpumask_test_cpu(cpu, to_cpumask(tick_broadcast_oneshot_mask))) {
 		struct tick_device *td = &per_cpu(tick_cpu_device, cpu);

 		clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_ONESHOT);
 	}
 }

 /*
  * Handle oneshot mode broadcasting
  */
 static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
 {
 	struct tick_device *td;
 	ktime_t now, next_event;
 	int cpu;

 	raw_spin_lock(&tick_broadcast_lock);
 again:
 	dev->next_event.tv64 = KTIME_MAX;
 	next_event.tv64 = KTIME_MAX;
 	cpumask_clear(to_cpumask(tmpmask));
 	now = ktime_get();
 	/* Find all expired events */
 	for_each_cpu(cpu, tick_get_broadcast_oneshot_mask()) {
 		td = &per_cpu(tick_cpu_device, cpu);
 		if (td->evtdev->next_event.tv64 <= now.tv64)
 			cpumask_set_cpu(cpu, to_cpumask(tmpmask));
 		else if (td->evtdev->next_event.tv64 < next_event.tv64)
 			next_event.tv64 = td->evtdev->next_event.tv64;
 	}

 	/*
 	 * Wakeup the cpus which have an expired event.
 	 */
 	tick_do_broadcast(to_cpumask(tmpmask));

 	/*
 	 * Two reasons for reprogram:
 	 *
 	 * - The global event did not expire any CPU local
 	 * events. This happens in dyntick mode, as the maximum PIT
 	 * delta is quite small.
 	 *
 	 * - There are pending events on sleeping CPUs which were not
 	 * in the event mask
 	 */
 	if (next_event.tv64 != KTIME_MAX) {
 		/*
 		 * Rearm the broadcast device. If event expired,
 		 * repeat the above
 		 */
 		if (tick_broadcast_set_event(next_event, 0))
 			goto again;
 	}
 	raw_spin_unlock(&tick_broadcast_lock);
 }

 /*
  * Powerstate information: The system enters/leaves a state, where
  * affected devices might stop
  */
 void tick_broadcast_oneshot_control(unsigned long reason)
 {
 	struct clock_event_device *bc, *dev;
 	struct tick_device *td;
 	unsigned long flags;
 	int cpu;

 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

 	/*
 	 * Periodic mode does not care about the enter/exit of power
 	 * states
 	 */
 	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
 		goto out;

 	bc = tick_broadcast_device.evtdev;
 	cpu = smp_processor_id();
 	td = &per_cpu(tick_cpu_device, cpu);
 	dev = td->evtdev;

 	if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
 		goto out;

 	if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
 		if (!cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) {
 			cpumask_set_cpu(cpu, tick_get_broadcast_oneshot_mask());
 			clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
 			if (dev->next_event.tv64 < bc->next_event.tv64)
 				tick_broadcast_set_event(dev->next_event, 1);
 		}
 	} else {
 		if (cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) {
 			cpumask_clear_cpu(cpu,
 					  tick_get_broadcast_oneshot_mask());
 			clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
 			if (dev->next_event.tv64 != KTIME_MAX)
 				tick_program_event(dev->next_event, 1);
 		}
 	}

 out:
 	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 }

 /*
  * Reset the one shot broadcast for a cpu
  *
  * Called with tick_broadcast_lock held
  */
 static void tick_broadcast_clear_oneshot(int cpu)
 {
 	cpumask_clear_cpu(cpu, tick_get_broadcast_oneshot_mask());
 }

 static void tick_broadcast_init_next_event(struct cpumask *mask,
 					   ktime_t expires)
 {
 	struct tick_device *td;
 	int cpu;

 	for_each_cpu(cpu, mask) {
 		td = &per_cpu(tick_cpu_device, cpu);
 		if (td->evtdev)
 			td->evtdev->next_event = expires;
 	}
 }

 /**
  * tick_broadcast_setup_oneshot - setup the broadcast device
  */
 void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
 {
 	/* Set it up only once ! */
 	if (bc->event_handler != tick_handle_oneshot_broadcast) {
 		int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC;
 		int cpu = smp_processor_id();

 		bc->event_handler = tick_handle_oneshot_broadcast;
 		clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);

 		/* Take the do_timer update */
 		tick_do_timer_cpu = cpu;

 		/*
 		 * We must be careful here. There might be other CPUs
 		 * waiting for periodic broadcast. We need to set the
 		 * oneshot_mask bits for those and program the
 		 * broadcast device to fire.
 		 */
 		cpumask_copy(to_cpumask(tmpmask), tick_get_broadcast_mask());
 		cpumask_clear_cpu(cpu, to_cpumask(tmpmask));
 		cpumask_or(tick_get_broadcast_oneshot_mask(),
 			   tick_get_broadcast_oneshot_mask(),
 			   to_cpumask(tmpmask));

 		if (was_periodic && !cpumask_empty(to_cpumask(tmpmask))) {
 			tick_broadcast_init_next_event(to_cpumask(tmpmask),
 						       tick_next_period);
 			tick_broadcast_set_event(tick_next_period, 1);
 		} else
 			bc->next_event.tv64 = KTIME_MAX;
 	}
 }

 /*
  * Select oneshot operating mode for the broadcast device
  */
 void tick_broadcast_switch_to_oneshot(void)
 {
 	struct clock_event_device *bc;
 	unsigned long flags;

 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

 	tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
 	bc = tick_broadcast_device.evtdev;
 	if (bc)
 		tick_broadcast_setup_oneshot(bc);
 	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 }


 /*
  * Remove a dead CPU from broadcasting
  */
 void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
 {
 	unsigned long flags;
 	unsigned int cpu = *cpup;

 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

 	/*
 	 * Clear the broadcast mask flag for the dead cpu, but do not
 	 * stop the broadcast device!
 	 */
 	cpumask_clear_cpu(cpu, tick_get_broadcast_oneshot_mask());

 	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 }

 /*
  * Check, whether the broadcast device is in one shot mode
  */
 int tick_broadcast_oneshot_active(void)
 {
 	return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
 }

 #endif
	/*
	* linux/kernel/time/tick-broadcast.c
	*
	* This file contains functions which emulate a local clock-event
	* device via a broadcast event source.
	*
	* Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
	* Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
	* Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
	*
	* This code is licenced under the GPL version 2. For details see
	* kernel-base/COPYING.
	*/
	#include <linux/cpu.h>
	#include <linux/err.h>
	#include <linux/hrtimer.h>
	#include <linux/interrupt.h>
	#include <linux/percpu.h>
	#include <linux/profile.h>
	#include <linux/sched.h>
	#include <linux/tick.h>

	#include "tick-internal.h"

	/*
	* Broadcast support for broken x86 hardware, where the local apic
	* timer stops in C3 state.
	*/

	static struct tick_device tick_broadcast_device;
	/* FIXME: Use cpumask_var_t. */
	static DECLARE_BITMAP(tick_broadcast_mask, NR_CPUS);
	static DECLARE_BITMAP(tmpmask, NR_CPUS);
	static DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
	static int tick_broadcast_force;

	#ifdef CONFIG_TICK_ONESHOT
	static void tick_broadcast_clear_oneshot(int cpu);
	#else
	static inline void tick_broadcast_clear_oneshot(int cpu) { }
	#endif

	/*
	* Debugging: see timer_list.c
	*/
	struct tick_device *tick_get_broadcast_device(void)
	{
	return &tick_broadcast_device;
	}

	struct cpumask *tick_get_broadcast_mask(void)
	{
	return to_cpumask(tick_broadcast_mask);
	}

	/*
	* Start the device in periodic mode
	*/
	static void tick_broadcast_start_periodic(struct clock_event_device *bc)
	{
	if (bc)
	tick_setup_periodic(bc, 1);
	}

	/*
	* Check, if the device can be utilized as broadcast device:
	*/
	int tick_check_broadcast_device(struct clock_event_device *dev)
	{
	if ((tick_broadcast_device.evtdev &&
	tick_broadcast_device.evtdev->rating >= dev->rating) \|\|
	(dev->features & CLOCK_EVT_FEAT_C3STOP))
	return 0;

	clockevents_exchange_device(NULL, dev);
	tick_broadcast_device.evtdev = dev;
	if (!cpumask_empty(tick_get_broadcast_mask()))
	tick_broadcast_start_periodic(dev);
	return 1;
	}

	/*
	* Check, if the device is the broadcast device
	*/
	int tick_is_broadcast_device(struct clock_event_device *dev)
	{
	return (dev && tick_broadcast_device.evtdev == dev);
	}

	/*
	* Check, if the device is disfunctional and a place holder, which
	* needs to be handled by the broadcast device.
	*/
	int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
	{
	unsigned long flags;
	int ret = 0;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

	/*
	* Devices might be registered with both periodic and oneshot
	* mode disabled. This signals, that the device needs to be
	* operated from the broadcast device and is a placeholder for
	* the cpu local device.
	*/
	if (!tick_device_is_functional(dev)) {
	dev->event_handler = tick_handle_periodic;
	cpumask_set_cpu(cpu, tick_get_broadcast_mask());
	tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
	ret = 1;
	} else {
	/*
	* When the new device is not affected by the stop
	* feature and the cpu is marked in the broadcast mask
	* then clear the broadcast bit.
	*/
	if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) {
	int cpu = smp_processor_id();

	cpumask_clear_cpu(cpu, tick_get_broadcast_mask());
	tick_broadcast_clear_oneshot(cpu);
	}
	}
	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
	return ret;
	}

	/*
	* Broadcast the event to the cpus, which are set in the mask (mangled).
	*/
	static void tick_do_broadcast(struct cpumask *mask)
	{
	int cpu = smp_processor_id();
	struct tick_device *td;

	/*
	* Check, if the current cpu is in the mask
	*/
	if (cpumask_test_cpu(cpu, mask)) {
	cpumask_clear_cpu(cpu, mask);
	td = &per_cpu(tick_cpu_device, cpu);
	td->evtdev->event_handler(td->evtdev);
	}

	if (!cpumask_empty(mask)) {
	/*
	* It might be necessary to actually check whether the devices
	* have different broadcast functions. For now, just use the
	* one of the first device. This works as long as we have this
	* misfeature only on x86 (lapic)
	*/
	td = &per_cpu(tick_cpu_device, cpumask_first(mask));
	td->evtdev->broadcast(mask);
	}
	}

	/*
	* Periodic broadcast:
	* - invoke the broadcast handlers
	*/
	static void tick_do_periodic_broadcast(void)
	{
	raw_spin_lock(&tick_broadcast_lock);

	cpumask_and(to_cpumask(tmpmask),
	cpu_online_mask, tick_get_broadcast_mask());
	tick_do_broadcast(to_cpumask(tmpmask));

	raw_spin_unlock(&tick_broadcast_lock);
	}

	/*
	* Event handler for periodic broadcast ticks
	*/
	static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
	{
	ktime_t next;

	tick_do_periodic_broadcast();

	/*
	* The device is in periodic mode. No reprogramming necessary:
	*/
	if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
	return;

	/*
	* Setup the next period for devices, which do not have
	* periodic mode. We read dev->next_event first and add to it
	* when the event alrady expired. clockevents_program_event()
	* sets dev->next_event only when the event is really
	* programmed to the device.
	*/
	for (next = dev->next_event; ;) {
	next = ktime_add(next, tick_period);

	if (!clockevents_program_event(dev, next, ktime_get()))
	return;
	tick_do_periodic_broadcast();
	}
	}

	/*
	* Powerstate information: The system enters/leaves a state, where
	* affected devices might stop
	*/
	static void tick_do_broadcast_on_off(unsigned long *reason)
	{
	struct clock_event_device bc, dev;
	struct tick_device *td;
	unsigned long flags;
	int cpu, bc_stopped;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

	cpu = smp_processor_id();
	td = &per_cpu(tick_cpu_device, cpu);
	dev = td->evtdev;
	bc = tick_broadcast_device.evtdev;

	/*
	* Is the device not affected by the powerstate ?
	*/
	if (!dev \|\| !(dev->features & CLOCK_EVT_FEAT_C3STOP))
	goto out;

	if (!tick_device_is_functional(dev))
	goto out;

	bc_stopped = cpumask_empty(tick_get_broadcast_mask());

	switch (*reason) {
	case CLOCK_EVT_NOTIFY_BROADCAST_ON:
	case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
	if (!cpumask_test_cpu(cpu, tick_get_broadcast_mask())) {
	cpumask_set_cpu(cpu, tick_get_broadcast_mask());
	if (tick_broadcast_device.mode ==
	TICKDEV_MODE_PERIODIC)
	clockevents_shutdown(dev);
	}
	if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_FORCE)
	tick_broadcast_force = 1;
	break;
	case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
	if (!tick_broadcast_force &&
	cpumask_test_cpu(cpu, tick_get_broadcast_mask())) {
	cpumask_clear_cpu(cpu, tick_get_broadcast_mask());
	if (tick_broadcast_device.mode ==
	TICKDEV_MODE_PERIODIC)
	tick_setup_periodic(dev, 0);
	}
	break;
	}

	if (cpumask_empty(tick_get_broadcast_mask())) {
	if (!bc_stopped)
	clockevents_shutdown(bc);
	} else if (bc_stopped) {
	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
	tick_broadcast_start_periodic(bc);
	else
	tick_broadcast_setup_oneshot(bc);
	}
	out:
	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
	}

	/*
	* Powerstate information: The system enters/leaves a state, where
	* affected devices might stop.
	*/
	void tick_broadcast_on_off(unsigned long reason, int *oncpu)
	{
	if (!cpumask_test_cpu(*oncpu, cpu_online_mask))
	printk(KERN_ERR "tick-broadcast: ignoring broadcast for "
	"offline CPU #%d\n", *oncpu);
	else
	tick_do_broadcast_on_off(&reason);
	}

	/*
	* Set the periodic handler depending on broadcast on/off
	*/
	void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
	{
	if (!broadcast)
	dev->event_handler = tick_handle_periodic;
	else
	dev->event_handler = tick_handle_periodic_broadcast;
	}

	/*
	* Remove a CPU from broadcasting
	*/
	void tick_shutdown_broadcast(unsigned int *cpup)
	{
	struct clock_event_device *bc;
	unsigned long flags;
	unsigned int cpu = *cpup;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

	bc = tick_broadcast_device.evtdev;
	cpumask_clear_cpu(cpu, tick_get_broadcast_mask());

	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
	if (bc && cpumask_empty(tick_get_broadcast_mask()))
	clockevents_shutdown(bc);
	}

	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
	}

	void tick_suspend_broadcast(void)
	{
	struct clock_event_device *bc;
	unsigned long flags;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

	bc = tick_broadcast_device.evtdev;
	if (bc)
	clockevents_shutdown(bc);

	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
	}

	int tick_resume_broadcast(void)
	{
	struct clock_event_device *bc;
	unsigned long flags;
	int broadcast = 0;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

	bc = tick_broadcast_device.evtdev;

	if (bc) {
	clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);

	switch (tick_broadcast_device.mode) {
	case TICKDEV_MODE_PERIODIC:
	if (!cpumask_empty(tick_get_broadcast_mask()))
	tick_broadcast_start_periodic(bc);
	broadcast = cpumask_test_cpu(smp_processor_id(),
	tick_get_broadcast_mask());
	break;
	case TICKDEV_MODE_ONESHOT:
	broadcast = tick_resume_broadcast_oneshot(bc);
	break;
	}
	}
	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);

	return broadcast;
	}


	#ifdef CONFIG_TICK_ONESHOT

	/* FIXME: use cpumask_var_t. */
	static DECLARE_BITMAP(tick_broadcast_oneshot_mask, NR_CPUS);

	/*
	* Exposed for debugging: see timer_list.c
	*/
	struct cpumask *tick_get_broadcast_oneshot_mask(void)
	{
	return to_cpumask(tick_broadcast_oneshot_mask);
	}

	static int tick_broadcast_set_event(ktime_t expires, int force)
	{
	struct clock_event_device *bc = tick_broadcast_device.evtdev;

	return tick_dev_program_event(bc, expires, force);
	}

	int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
	{
	clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
	return 0;
	}

	/*
	* Called from irq_enter() when idle was interrupted to reenable the
	* per cpu device.
	*/
	void tick_check_oneshot_broadcast(int cpu)
	{
	if (cpumask_test_cpu(cpu, to_cpumask(tick_broadcast_oneshot_mask))) {
	struct tick_device *td = &per_cpu(tick_cpu_device, cpu);

	clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_ONESHOT);
	}
	}

	/*
	* Handle oneshot mode broadcasting
	*/
	static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
	{
	struct tick_device *td;
	ktime_t now, next_event;
	int cpu;

	raw_spin_lock(&tick_broadcast_lock);
	again:
	dev->next_event.tv64 = KTIME_MAX;
	next_event.tv64 = KTIME_MAX;
	cpumask_clear(to_cpumask(tmpmask));
	now = ktime_get();
	/* Find all expired events */
	for_each_cpu(cpu, tick_get_broadcast_oneshot_mask()) {
	td = &per_cpu(tick_cpu_device, cpu);
	if (td->evtdev->next_event.tv64 <= now.tv64)
	cpumask_set_cpu(cpu, to_cpumask(tmpmask));
	else if (td->evtdev->next_event.tv64 < next_event.tv64)
	next_event.tv64 = td->evtdev->next_event.tv64;
	}

	/*
	* Wakeup the cpus which have an expired event.
	*/
	tick_do_broadcast(to_cpumask(tmpmask));

	/*
	* Two reasons for reprogram:
	*
	* - The global event did not expire any CPU local
	* events. This happens in dyntick mode, as the maximum PIT
	* delta is quite small.
	*
	* - There are pending events on sleeping CPUs which were not
	* in the event mask
	*/
	if (next_event.tv64 != KTIME_MAX) {
	/*
	* Rearm the broadcast device. If event expired,
	* repeat the above
	*/
	if (tick_broadcast_set_event(next_event, 0))
	goto again;
	}
	raw_spin_unlock(&tick_broadcast_lock);
	}

	/*
	* Powerstate information: The system enters/leaves a state, where
	* affected devices might stop
	*/
	void tick_broadcast_oneshot_control(unsigned long reason)
	{
	struct clock_event_device bc, dev;
	struct tick_device *td;
	unsigned long flags;
	int cpu;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

	/*
	* Periodic mode does not care about the enter/exit of power
	* states
	*/
	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
	goto out;

	bc = tick_broadcast_device.evtdev;
	cpu = smp_processor_id();
	td = &per_cpu(tick_cpu_device, cpu);
	dev = td->evtdev;

	if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
	goto out;

	if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
	if (!cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) {
	cpumask_set_cpu(cpu, tick_get_broadcast_oneshot_mask());
	clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
	if (dev->next_event.tv64 < bc->next_event.tv64)
	tick_broadcast_set_event(dev->next_event, 1);
	}
	} else {
	if (cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) {
	cpumask_clear_cpu(cpu,
	tick_get_broadcast_oneshot_mask());
	clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
	if (dev->next_event.tv64 != KTIME_MAX)
	tick_program_event(dev->next_event, 1);
	}
	}

	out:
	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
	}

	/*
	* Reset the one shot broadcast for a cpu
	*
	* Called with tick_broadcast_lock held
	*/
	static void tick_broadcast_clear_oneshot(int cpu)
	{
	cpumask_clear_cpu(cpu, tick_get_broadcast_oneshot_mask());
	}

	static void tick_broadcast_init_next_event(struct cpumask *mask,
	ktime_t expires)
	{
	struct tick_device *td;
	int cpu;

	for_each_cpu(cpu, mask) {
	td = &per_cpu(tick_cpu_device, cpu);
	if (td->evtdev)
	td->evtdev->next_event = expires;
	}
	}

	/**
	* tick_broadcast_setup_oneshot - setup the broadcast device
	*/
	void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
	{
	/* Set it up only once ! */
	if (bc->event_handler != tick_handle_oneshot_broadcast) {
	int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC;
	int cpu = smp_processor_id();

	bc->event_handler = tick_handle_oneshot_broadcast;
	clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);

	/* Take the do_timer update */
	tick_do_timer_cpu = cpu;

	/*
	* We must be careful here. There might be other CPUs
	* waiting for periodic broadcast. We need to set the
	* oneshot_mask bits for those and program the
	* broadcast device to fire.
	*/
	cpumask_copy(to_cpumask(tmpmask), tick_get_broadcast_mask());
	cpumask_clear_cpu(cpu, to_cpumask(tmpmask));
	cpumask_or(tick_get_broadcast_oneshot_mask(),
	tick_get_broadcast_oneshot_mask(),
	to_cpumask(tmpmask));

	if (was_periodic && !cpumask_empty(to_cpumask(tmpmask))) {
	tick_broadcast_init_next_event(to_cpumask(tmpmask),
	tick_next_period);
	tick_broadcast_set_event(tick_next_period, 1);
	} else
	bc->next_event.tv64 = KTIME_MAX;
	}
	}

	/*
	* Select oneshot operating mode for the broadcast device
	*/
	void tick_broadcast_switch_to_oneshot(void)
	{
	struct clock_event_device *bc;
	unsigned long flags;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

	tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
	bc = tick_broadcast_device.evtdev;
	if (bc)
	tick_broadcast_setup_oneshot(bc);
	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
	}


	/*
	* Remove a dead CPU from broadcasting
	*/
	void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
	{
	unsigned long flags;
	unsigned int cpu = *cpup;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

	/*
	* Clear the broadcast mask flag for the dead cpu, but do not
	* stop the broadcast device!
	*/
	cpumask_clear_cpu(cpu, tick_get_broadcast_oneshot_mask());

	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
	}

	/*
	* Check, whether the broadcast device is in one shot mode
	*/
	int tick_broadcast_oneshot_active(void)
	{
	return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
	}

	#endif