[linux-2.6-block.git] / kernel / time / tick-broadcast.c

/*
 * 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/irq.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.
 */

struct tick_device tick_broadcast_device;
static cpumask_t tick_broadcast_mask;
static DEFINE_SPINLOCK(tick_broadcast_lock);

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

cpumask_t *tick_get_broadcast_mask(void)
{
	return &tick_broadcast_mask;
}

/*
 * Start the device in periodic mode
 */
static void tick_broadcast_start_periodic(struct clock_event_device *bc)
{
	if (bc && bc->mode == CLOCK_EVT_MODE_SHUTDOWN)
		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 ||
	    (dev->features & CLOCK_EVT_FEAT_C3STOP))
		return 0;

	clockevents_exchange_device(NULL, dev);
	tick_broadcast_device.evtdev = dev;
	if (!cpus_empty(tick_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;

	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;
		cpu_set(cpu, tick_broadcast_mask);
		tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
		ret = 1;
	}

	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
	return ret;
}

/*
 * Broadcast the event to the cpus, which are set in the mask
 */
int tick_do_broadcast(cpumask_t mask)
{
	int ret = 0, cpu = smp_processor_id();
	struct tick_device *td;

	/*
	 * Check, if the current cpu is in the mask
	 */
	if (cpu_isset(cpu, mask)) {
		cpu_clear(cpu, mask);
		td = &per_cpu(tick_cpu_device, cpu);
		td->evtdev->event_handler(td->evtdev);
		ret = 1;
	}

	if (!cpus_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)
		 */
		cpu = first_cpu(mask);
		td = &per_cpu(tick_cpu_device, cpu);
		td->evtdev->broadcast(mask);
		ret = 1;
	}
	return ret;
}

/*
 * Periodic broadcast:
 * - invoke the broadcast handlers
 */
static void tick_do_periodic_broadcast(void)
{
	cpumask_t mask;

	spin_lock(&tick_broadcast_lock);

	cpus_and(mask, cpu_online_map, tick_broadcast_mask);
	tick_do_broadcast(mask);

	spin_unlock(&tick_broadcast_lock);
}

/*
 * Event handler for periodic broadcast ticks
 */
static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
{
	dev->next_event.tv64 = KTIME_MAX;

	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:
	 */
	for (;;) {
		ktime_t next = ktime_add(dev->next_event, 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(void *why)
{
	struct clock_event_device *bc, *dev;
	struct tick_device *td;
	unsigned long flags, *reason = why;
	int cpu;

	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 in broadcast mode forever or is it not
	 * affected by the powerstate ?
	 */
	if (!dev || !tick_device_is_functional(dev) ||
	    !(dev->features & CLOCK_EVT_FEAT_C3STOP))
		goto out;

	if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_ON) {
		if (!cpu_isset(cpu, tick_broadcast_mask)) {
			cpu_set(cpu, tick_broadcast_mask);
			if (td->mode == TICKDEV_MODE_PERIODIC)
				clockevents_set_mode(dev,
						     CLOCK_EVT_MODE_SHUTDOWN);
		}
	} else {
		if (cpu_isset(cpu, tick_broadcast_mask)) {
			cpu_clear(cpu, tick_broadcast_mask);
			if (td->mode == TICKDEV_MODE_PERIODIC)
				tick_setup_periodic(dev, 0);
		}
	}

	if (cpus_empty(tick_broadcast_mask))
		clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
	else {
		if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
			tick_broadcast_start_periodic(bc);
		else
			tick_broadcast_setup_oneshot(bc);
	}
out:
	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)
{
	int cpu = get_cpu();

	if (cpu == *oncpu)
		tick_do_broadcast_on_off(&reason);
	else
		smp_call_function_single(*oncpu, tick_do_broadcast_on_off,
					 &reason, 1, 1);
	put_cpu();
}

/*
 * 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;

	spin_lock_irqsave(&tick_broadcast_lock, flags);

	bc = tick_broadcast_device.evtdev;
	cpu_clear(cpu, tick_broadcast_mask);

	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
		if (bc && cpus_empty(tick_broadcast_mask))
			clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
	}

	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}

#ifdef CONFIG_TICK_ONESHOT

static cpumask_t tick_broadcast_oneshot_mask;

/*
 * Debugging: see timer_list.c
 */
cpumask_t *tick_get_broadcast_oneshot_mask(void)
{
	return &tick_broadcast_oneshot_mask;
}

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

	for(;;) {
		res = clockevents_program_event(bc, expires, now);
		if (!res || !force)
			return res;
		now = ktime_get();
		expires = ktime_add(now, ktime_set(0, bc->min_delta_ns));
	}
}

/*
 * Reprogram the broadcast device:
 *
 * Called with tick_broadcast_lock held and interrupts disabled.
 */
static int tick_broadcast_reprogram(void)
{
	ktime_t expires = { .tv64 = KTIME_MAX };
	struct tick_device *td;
	int cpu;

	/*
	 * Find the event which expires next:
	 */
	for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
	     cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
		td = &per_cpu(tick_cpu_device, cpu);
		if (td->evtdev->next_event.tv64 < expires.tv64)
			expires = td->evtdev->next_event;
	}

	if (expires.tv64 == KTIME_MAX)
		return 0;

	return tick_broadcast_set_event(expires, 0);
}

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

	spin_lock(&tick_broadcast_lock);
again:
	dev->next_event.tv64 = KTIME_MAX;
	mask = CPU_MASK_NONE;
	now = ktime_get();
	/* Find all expired events */
	for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
	     cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
		td = &per_cpu(tick_cpu_device, cpu);
		if (td->evtdev->next_event.tv64 <= now.tv64)
			cpu_set(cpu, mask);
	}

	/*
	 * Wakeup the cpus which have an expired event. The broadcast
	 * device is reprogrammed in the return from idle code.
	 */
	if (!tick_do_broadcast(mask)) {
		/*
		 * The global event did not expire any CPU local
		 * events. This happens in dyntick mode, as the
		 * maximum PIT delta is quite small.
		 */
		if (tick_broadcast_reprogram())
			goto again;
	}
	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;

	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 (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
			cpu_set(cpu, tick_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 (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
			cpu_clear(cpu, tick_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:
	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}

/**
 * tick_broadcast_setup_highres - setup the broadcast device for highres
 */
void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
{
	if (bc->mode != CLOCK_EVT_MODE_ONESHOT) {
		bc->event_handler = tick_handle_oneshot_broadcast;
		clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
		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;

	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);
	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}


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

	spin_lock_irqsave(&tick_broadcast_lock, flags);

	bc = tick_broadcast_device.evtdev;
	cpu_clear(cpu, tick_broadcast_oneshot_mask);

	if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT) {
		if (bc && cpus_empty(tick_broadcast_oneshot_mask))
			clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
	}

	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}

#endif
Commit	Line	Data
f8381cba TG	1	/*
	2	* linux/kernel/time/tick-broadcast.c
	3	*
	4	* This file contains functions which emulate a local clock-event
	5	* device via a broadcast event source.
	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/irq.h>
	18	#include <linux/percpu.h>
	19	#include <linux/profile.h>
	20	#include <linux/sched.h>
	21	#include <linux/tick.h>
	22
	23	#include "tick-internal.h"
	24
	25	/*
	26	* Broadcast support for broken x86 hardware, where the local apic
	27	* timer stops in C3 state.
	28	*/
	29
	30	struct tick_device tick_broadcast_device;
	31	static cpumask_t tick_broadcast_mask;
79bf2bb3	32	static DEFINE_SPINLOCK(tick_broadcast_lock);
f8381cba	33
289f480a IM	34	/*
	35	* Debugging: see timer_list.c
	36	*/
	37	struct tick_device *tick_get_broadcast_device(void)
	38	{
	39	return &tick_broadcast_device;
	40	}
	41
	42	cpumask_t *tick_get_broadcast_mask(void)
	43	{
	44	return &tick_broadcast_mask;
	45	}
	46
f8381cba TG	47	/*
	48	* Start the device in periodic mode
	49	*/
	50	static void tick_broadcast_start_periodic(struct clock_event_device *bc)
	51	{
	52	if (bc && bc->mode == CLOCK_EVT_MODE_SHUTDOWN)
	53	tick_setup_periodic(bc, 1);
	54	}
	55
	56	/*
	57	* Check, if the device can be utilized as broadcast device:
	58	*/
	59	int tick_check_broadcast_device(struct clock_event_device *dev)
	60	{
	61	if (tick_broadcast_device.evtdev \|\|
	62	(dev->features & CLOCK_EVT_FEAT_C3STOP))
	63	return 0;
	64
	65	clockevents_exchange_device(NULL, dev);
	66	tick_broadcast_device.evtdev = dev;
	67	if (!cpus_empty(tick_broadcast_mask))
	68	tick_broadcast_start_periodic(dev);
	69	return 1;
	70	}
	71
	72	/*
	73	* Check, if the device is the broadcast device
	74	*/
	75	int tick_is_broadcast_device(struct clock_event_device *dev)
	76	{
	77	return (dev && tick_broadcast_device.evtdev == dev);
	78	}
	79
	80	/*
	81	* Check, if the device is disfunctional and a place holder, which
	82	* needs to be handled by the broadcast device.
	83	*/
	84	int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
	85	{
	86	unsigned long flags;
	87	int ret = 0;
	88
	89	spin_lock_irqsave(&tick_broadcast_lock, flags);
	90
	91	/*
	92	* Devices might be registered with both periodic and oneshot
	93	* mode disabled. This signals, that the device needs to be
	94	* operated from the broadcast device and is a placeholder for
	95	* the cpu local device.
	96	*/
	97	if (!tick_device_is_functional(dev)) {
	98	dev->event_handler = tick_handle_periodic;
	99	cpu_set(cpu, tick_broadcast_mask);
	100	tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
	101	ret = 1;
	102	}
	103
	104	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
	105	return ret;
	106	}
	107
	108	/*
	109	* Broadcast the event to the cpus, which are set in the mask
	110	*/
111	int tick_do_broadcast(cpumask_t mask)
112	{
113	int ret = 0, cpu = smp_processor_id();
114	struct tick_device *td;
115
116	/*
117	* Check, if the current cpu is in the mask
118	*/
119	if (cpu_isset(cpu, mask)) {
120	cpu_clear(cpu, mask);
121	td = &per_cpu(tick_cpu_device, cpu);
122	td->evtdev->event_handler(td->evtdev);
123	ret = 1;
124	}
125
126	if (!cpus_empty(mask)) {
127	/*
128	* It might be necessary to actually check whether the devices
129	* have different broadcast functions. For now, just use the
130	* one of the first device. This works as long as we have this
131	* misfeature only on x86 (lapic)
132	*/
133	cpu = first_cpu(mask);
134	td = &per_cpu(tick_cpu_device, cpu);
135	td->evtdev->broadcast(mask);
136	ret = 1;
137	}
138	return ret;
139	}
140
141	/*
142	* Periodic broadcast:
143	* - invoke the broadcast handlers
144	*/
145	static void tick_do_periodic_broadcast(void)
146	{
147	cpumask_t mask;
148
149	spin_lock(&tick_broadcast_lock);
150
151	cpus_and(mask, cpu_online_map, tick_broadcast_mask);
152	tick_do_broadcast(mask);
153
154	spin_unlock(&tick_broadcast_lock);
155	}
156
157	/*
158	* Event handler for periodic broadcast ticks
159	*/
160	static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
161	{
162	dev->next_event.tv64 = KTIME_MAX;
163
164	tick_do_periodic_broadcast();
165
166	/*
167	* The device is in periodic mode. No reprogramming necessary:
168	*/
169	if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
170	return;
171
172	/*
173	* Setup the next period for devices, which do not have
174	* periodic mode:
175	*/
176	for (;;) {
177	ktime_t next = ktime_add(dev->next_event, tick_period);
178
179	if (!clockevents_program_event(dev, next, ktime_get()))
180	return;
181	tick_do_periodic_broadcast();
182	}
183	}
184
185	/*
186	* Powerstate information: The system enters/leaves a state, where
187	* affected devices might stop
188	*/
189	static void tick_do_broadcast_on_off(void *why)
190	{
191	struct clock_event_device bc, dev;
192	struct tick_device *td;
193	unsigned long flags, *reason = why;
194	int cpu;
195
196	spin_lock_irqsave(&tick_broadcast_lock, flags);
197
198	cpu = smp_processor_id();
199	td = &per_cpu(tick_cpu_device, cpu);
200	dev = td->evtdev;
201	bc = tick_broadcast_device.evtdev;
202
203	/*
204	* Is the device in broadcast mode forever or is it not
205	* affected by the powerstate ?
206	*/
207	if (!dev \|\| !tick_device_is_functional(dev) \|\|
208	!(dev->features & CLOCK_EVT_FEAT_C3STOP))
209	goto out;
210
211	if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_ON) {
212	if (!cpu_isset(cpu, tick_broadcast_mask)) {
213	cpu_set(cpu, tick_broadcast_mask);
214	if (td->mode == TICKDEV_MODE_PERIODIC)
215	clockevents_set_mode(dev,
216	CLOCK_EVT_MODE_SHUTDOWN);
217	}
218	} else {
219	if (cpu_isset(cpu, tick_broadcast_mask)) {
220	cpu_clear(cpu, tick_broadcast_mask);
221	if (td->mode == TICKDEV_MODE_PERIODIC)
222	tick_setup_periodic(dev, 0);
223	}
224	}
225
226	if (cpus_empty(tick_broadcast_mask))
227	clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
228	else {
229	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
230	tick_broadcast_start_periodic(bc);
79bf2bb3 TG	231	else
79bf2bb3 TG	232	tick_broadcast_setup_oneshot(bc);
f8381cba TG	233	}
	234	out:
	235	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
	236	}
	237
	238	/*
	239	* Powerstate information: The system enters/leaves a state, where
	240	* affected devices might stop.
	241	*/
	242	void tick_broadcast_on_off(unsigned long reason, int *oncpu)
	243	{
	244	int cpu = get_cpu();
	245
	246	if (cpu == *oncpu)
	247	tick_do_broadcast_on_off(&reason);
	248	else
	249	smp_call_function_single(*oncpu, tick_do_broadcast_on_off,
	250	&reason, 1, 1);
	251	put_cpu();
	252	}
	253
	254	/*
	255	* Set the periodic handler depending on broadcast on/off
	256	*/
	257	void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
	258	{
	259	if (!broadcast)
	260	dev->event_handler = tick_handle_periodic;
	261	else
	262	dev->event_handler = tick_handle_periodic_broadcast;
	263	}
	264
	265	/*
	266	* Remove a CPU from broadcasting
	267	*/
	268	void tick_shutdown_broadcast(unsigned int *cpup)
	269	{
	270	struct clock_event_device *bc;
	271	unsigned long flags;
	272	unsigned int cpu = *cpup;
	273
	274	spin_lock_irqsave(&tick_broadcast_lock, flags);
	275
	276	bc = tick_broadcast_device.evtdev;
	277	cpu_clear(cpu, tick_broadcast_mask);
	278
	279	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
	280	if (bc && cpus_empty(tick_broadcast_mask))
	281	clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
	282	}
	283
	284	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
	285	}
79bf2bb3 TG	286
	287	#ifdef CONFIG_TICK_ONESHOT
	288
	289	static cpumask_t tick_broadcast_oneshot_mask;
	290
289f480a IM	291	/*
	292	* Debugging: see timer_list.c
	293	*/
	294	cpumask_t *tick_get_broadcast_oneshot_mask(void)
	295	{
	296	return &tick_broadcast_oneshot_mask;
	297	}
	298
79bf2bb3 TG	299	static int tick_broadcast_set_event(ktime_t expires, int force)
	300	{
	301	struct clock_event_device *bc = tick_broadcast_device.evtdev;
	302	ktime_t now = ktime_get();
	303	int res;
	304
	305	for(;;) {
	306	res = clockevents_program_event(bc, expires, now);
	307	if (!res \|\| !force)
	308	return res;
	309	now = ktime_get();
	310	expires = ktime_add(now, ktime_set(0, bc->min_delta_ns));
	311	}
	312	}
	313
	314	/*
	315	* Reprogram the broadcast device:
	316	*
	317	* Called with tick_broadcast_lock held and interrupts disabled.
	318	*/
	319	static int tick_broadcast_reprogram(void)
	320	{
	321	ktime_t expires = { .tv64 = KTIME_MAX };
	322	struct tick_device *td;
	323	int cpu;
	324
	325	/*
	326	* Find the event which expires next:
	327	*/
	328	for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
	329	cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
	330	td = &per_cpu(tick_cpu_device, cpu);
	331	if (td->evtdev->next_event.tv64 < expires.tv64)
	332	expires = td->evtdev->next_event;
	333	}
	334
	335	if (expires.tv64 == KTIME_MAX)
	336	return 0;
	337
	338	return tick_broadcast_set_event(expires, 0);
	339	}
	340
	341	/*
	342	* Handle oneshot mode broadcasting
	343	*/
	344	static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
	345	{
	346	struct tick_device *td;
	347	cpumask_t mask;
	348	ktime_t now;
	349	int cpu;
	350
	351	spin_lock(&tick_broadcast_lock);
	352	again:
	353	dev->next_event.tv64 = KTIME_MAX;
	354	mask = CPU_MASK_NONE;
	355	now = ktime_get();
	356	/* Find all expired events */
	357	for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
	358	cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
	359	td = &per_cpu(tick_cpu_device, cpu);
	360	if (td->evtdev->next_event.tv64 <= now.tv64)
	361	cpu_set(cpu, mask);
	362	}
363
364	/*
365	* Wakeup the cpus which have an expired event. The broadcast
366	* device is reprogrammed in the return from idle code.
367	*/
368	if (!tick_do_broadcast(mask)) {
369	/*
370	* The global event did not expire any CPU local
371	* events. This happens in dyntick mode, as the
372	* maximum PIT delta is quite small.
373	*/
374	if (tick_broadcast_reprogram())
375	goto again;
376	}
377	spin_unlock(&tick_broadcast_lock);
378	}
379
380	/*
381	* Powerstate information: The system enters/leaves a state, where
382	* affected devices might stop
383	*/
384	void tick_broadcast_oneshot_control(unsigned long reason)
385	{
386	struct clock_event_device bc, dev;
387	struct tick_device *td;
388	unsigned long flags;
389	int cpu;
390
391	spin_lock_irqsave(&tick_broadcast_lock, flags);
392
393	/*
394	* Periodic mode does not care about the enter/exit of power
395	* states
396	*/
397	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
398	goto out;
399
400	bc = tick_broadcast_device.evtdev;
401	cpu = smp_processor_id();
402	td = &per_cpu(tick_cpu_device, cpu);
403	dev = td->evtdev;
404
405	if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
406	goto out;
407
408	if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
409	if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
410	cpu_set(cpu, tick_broadcast_oneshot_mask);
411	clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
412	if (dev->next_event.tv64 < bc->next_event.tv64)
413	tick_broadcast_set_event(dev->next_event, 1);
414	}
415	} else {
416	if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
417	cpu_clear(cpu, tick_broadcast_oneshot_mask);
418	clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
419	if (dev->next_event.tv64 != KTIME_MAX)
420	tick_program_event(dev->next_event, 1);
421	}
422	}
423
424	out:
425	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
426	}
427
428	/**
429	* tick_broadcast_setup_highres - setup the broadcast device for highres
430	*/
431	void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
432	{
433	if (bc->mode != CLOCK_EVT_MODE_ONESHOT) {
434	bc->event_handler = tick_handle_oneshot_broadcast;
435	clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
436	bc->next_event.tv64 = KTIME_MAX;
437	}
438	}
439
440	/*
441	* Select oneshot operating mode for the broadcast device
442	*/
443	void tick_broadcast_switch_to_oneshot(void)
444	{
445	struct clock_event_device *bc;
446	unsigned long flags;
447
448	spin_lock_irqsave(&tick_broadcast_lock, flags);
449
450	tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
451	bc = tick_broadcast_device.evtdev;
452	if (bc)
453	tick_broadcast_setup_oneshot(bc);
454	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
455	}
456
457
458	/*
459	* Remove a dead CPU from broadcasting
460	*/
461	void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
462	{
463	struct clock_event_device *bc;
464	unsigned long flags;
465	unsigned int cpu = *cpup;
466
467	spin_lock_irqsave(&tick_broadcast_lock, flags);
468
469	bc = tick_broadcast_device.evtdev;
470	cpu_clear(cpu, tick_broadcast_oneshot_mask);
471
472	if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT) {
473	if (bc && cpus_empty(tick_broadcast_oneshot_mask))
474	clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
475	}
476
477	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
478	}
479
480	#endif