[net-next-2.6.git] / kernel / time / clockevents.c

/*
 * linux/kernel/time/clockevents.c
 *
 * This file contains functions which manage clock event devices.
 *
 * 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/clockchips.h>
#include <linux/hrtimer.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/smp.h>
#include <linux/sysdev.h>
#include <linux/tick.h>

#include "tick-internal.h"

/* The registered clock event devices */
static LIST_HEAD(clockevent_devices);
static LIST_HEAD(clockevents_released);

/* Notification for clock events */
static RAW_NOTIFIER_HEAD(clockevents_chain);

/* Protection for the above */
static DEFINE_RAW_SPINLOCK(clockevents_lock);

/**
 * clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds
 * @latch:	value to convert
 * @evt:	pointer to clock event device descriptor
 *
 * Math helper, returns latch value converted to nanoseconds (bound checked)
 */
u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
{
	u64 clc = (u64) latch << evt->shift;

	if (unlikely(!evt->mult)) {
		evt->mult = 1;
		WARN_ON(1);
	}

	do_div(clc, evt->mult);
	if (clc < 1000)
		clc = 1000;
	if (clc > KTIME_MAX)
		clc = KTIME_MAX;

	return clc;
}
EXPORT_SYMBOL_GPL(clockevent_delta2ns);

/**
 * clockevents_set_mode - set the operating mode of a clock event device
 * @dev:	device to modify
 * @mode:	new mode
 *
 * Must be called with interrupts disabled !
 */
void clockevents_set_mode(struct clock_event_device *dev,
				 enum clock_event_mode mode)
{
	if (dev->mode != mode) {
		dev->set_mode(mode, dev);
		dev->mode = mode;

		/*
		 * A nsec2cyc multiplicator of 0 is invalid and we'd crash
		 * on it, so fix it up and emit a warning:
		 */
		if (mode == CLOCK_EVT_MODE_ONESHOT) {
			if (unlikely(!dev->mult)) {
				dev->mult = 1;
				WARN_ON(1);
			}
		}
	}
}

/**
 * clockevents_shutdown - shutdown the device and clear next_event
 * @dev:	device to shutdown
 */
void clockevents_shutdown(struct clock_event_device *dev)
{
	clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
	dev->next_event.tv64 = KTIME_MAX;
}

/**
 * clockevents_program_event - Reprogram the clock event device.
 * @expires:	absolute expiry time (monotonic clock)
 *
 * Returns 0 on success, -ETIME when the event is in the past.
 */
int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
			      ktime_t now)
{
	unsigned long long clc;
	int64_t delta;

	if (unlikely(expires.tv64 < 0)) {
		WARN_ON_ONCE(1);
		return -ETIME;
	}

	delta = ktime_to_ns(ktime_sub(expires, now));

	if (delta <= 0)
		return -ETIME;

	dev->next_event = expires;

	if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
		return 0;

	if (delta > dev->max_delta_ns)
		delta = dev->max_delta_ns;
	if (delta < dev->min_delta_ns)
		delta = dev->min_delta_ns;

	clc = delta * dev->mult;
	clc >>= dev->shift;

	return dev->set_next_event((unsigned long) clc, dev);
}

/**
 * clockevents_register_notifier - register a clock events change listener
 */
int clockevents_register_notifier(struct notifier_block *nb)
{
	unsigned long flags;
	int ret;

	raw_spin_lock_irqsave(&clockevents_lock, flags);
	ret = raw_notifier_chain_register(&clockevents_chain, nb);
	raw_spin_unlock_irqrestore(&clockevents_lock, flags);

	return ret;
}

/*
 * Notify about a clock event change. Called with clockevents_lock
 * held.
 */
static void clockevents_do_notify(unsigned long reason, void *dev)
{
	raw_notifier_call_chain(&clockevents_chain, reason, dev);
}

/*
 * Called after a notify add to make devices available which were
 * released from the notifier call.
 */
static void clockevents_notify_released(void)
{
	struct clock_event_device *dev;

	while (!list_empty(&clockevents_released)) {
		dev = list_entry(clockevents_released.next,
				 struct clock_event_device, list);
		list_del(&dev->list);
		list_add(&dev->list, &clockevent_devices);
		clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev);
	}
}

/**
 * clockevents_register_device - register a clock event device
 * @dev:	device to register
 */
void clockevents_register_device(struct clock_event_device *dev)
{
	unsigned long flags;

	BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
	BUG_ON(!dev->cpumask);

	raw_spin_lock_irqsave(&clockevents_lock, flags);

	list_add(&dev->list, &clockevent_devices);
	clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev);
	clockevents_notify_released();

	raw_spin_unlock_irqrestore(&clockevents_lock, flags);
}
EXPORT_SYMBOL_GPL(clockevents_register_device);

/*
 * Noop handler when we shut down an event device
 */
void clockevents_handle_noop(struct clock_event_device *dev)
{
}

/**
 * clockevents_exchange_device - release and request clock devices
 * @old:	device to release (can be NULL)
 * @new:	device to request (can be NULL)
 *
 * Called from the notifier chain. clockevents_lock is held already
 */
void clockevents_exchange_device(struct clock_event_device *old,
				 struct clock_event_device *new)
{
	unsigned long flags;

	local_irq_save(flags);
	/*
	 * Caller releases a clock event device. We queue it into the
	 * released list and do a notify add later.
	 */
	if (old) {
		clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED);
		list_del(&old->list);
		list_add(&old->list, &clockevents_released);
	}

	if (new) {
		BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED);
		clockevents_shutdown(new);
	}
	local_irq_restore(flags);
}

#ifdef CONFIG_GENERIC_CLOCKEVENTS
/**
 * clockevents_notify - notification about relevant events
 */
void clockevents_notify(unsigned long reason, void *arg)
{
	struct clock_event_device *dev, *tmp;
	unsigned long flags;
	int cpu;

	raw_spin_lock_irqsave(&clockevents_lock, flags);
	clockevents_do_notify(reason, arg);

	switch (reason) {
	case CLOCK_EVT_NOTIFY_CPU_DEAD:
		/*
		 * Unregister the clock event devices which were
		 * released from the users in the notify chain.
		 */
		list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
			list_del(&dev->list);
		/*
		 * Now check whether the CPU has left unused per cpu devices
		 */
		cpu = *((int *)arg);
		list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
			if (cpumask_test_cpu(cpu, dev->cpumask) &&
			    cpumask_weight(dev->cpumask) == 1 &&
			    !tick_is_broadcast_device(dev)) {
				BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
				list_del(&dev->list);
			}
		}
		break;
	default:
		break;
	}
	raw_spin_unlock_irqrestore(&clockevents_lock, flags);
}
EXPORT_SYMBOL_GPL(clockevents_notify);
#endif
Commit	Line	Data
d316c57f TG	1	/*
	2	* linux/kernel/time/clockevents.c
	3	*
	4	* This file contains functions which manage clock event devices.
	5	*
	6	* Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
	7	* Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
	8	* Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
	9	*
	10	* This code is licenced under the GPL version 2. For details see
	11	* kernel-base/COPYING.
	12	*/
	13
	14	#include <linux/clockchips.h>
	15	#include <linux/hrtimer.h>
	16	#include <linux/init.h>
	17	#include <linux/module.h>
	18	#include <linux/notifier.h>
	19	#include <linux/smp.h>
	20	#include <linux/sysdev.h>
eea08f32	21	#include <linux/tick.h>
d316c57f	22
8e1a928a HS	23	#include "tick-internal.h"
8e1a928a HS	24
d316c57f TG	25	/* The registered clock event devices */
	26	static LIST_HEAD(clockevent_devices);
	27	static LIST_HEAD(clockevents_released);
	28
	29	/* Notification for clock events */
	30	static RAW_NOTIFIER_HEAD(clockevents_chain);
	31
	32	/* Protection for the above */
b5f91da0	33	static DEFINE_RAW_SPINLOCK(clockevents_lock);
d316c57f TG	34
	35	/**
	36	* clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds
	37	* @latch: value to convert
	38	* @evt: pointer to clock event device descriptor
	39	*
	40	* Math helper, returns latch value converted to nanoseconds (bound checked)
	41	*/
97813f2f	42	u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
d316c57f	43	{
97813f2f	44	u64 clc = (u64) latch << evt->shift;
d316c57f	45
45fe4fe1 IM	46	if (unlikely(!evt->mult)) {
	47	evt->mult = 1;
	48	WARN_ON(1);
	49	}
	50
d316c57f TG	51	do_div(clc, evt->mult);
	52	if (clc < 1000)
	53	clc = 1000;
97813f2f JH	54	if (clc > KTIME_MAX)
97813f2f JH	55	clc = KTIME_MAX;
d316c57f	56
97813f2f	57	return clc;
d316c57f	58	}
c81fc2c3	59	EXPORT_SYMBOL_GPL(clockevent_delta2ns);
d316c57f TG	60
	61	/**
	62	* clockevents_set_mode - set the operating mode of a clock event device
	63	* @dev: device to modify
	64	* @mode: new mode
	65	*
	66	* Must be called with interrupts disabled !
	67	*/
	68	void clockevents_set_mode(struct clock_event_device *dev,
	69	enum clock_event_mode mode)
	70	{
	71	if (dev->mode != mode) {
	72	dev->set_mode(mode, dev);
	73	dev->mode = mode;
2d68259d MD	74
	75	/*
	76	* A nsec2cyc multiplicator of 0 is invalid and we'd crash
	77	* on it, so fix it up and emit a warning:
	78	*/
	79	if (mode == CLOCK_EVT_MODE_ONESHOT) {
	80	if (unlikely(!dev->mult)) {
	81	dev->mult = 1;
	82	WARN_ON(1);
	83	}
	84	}
d316c57f TG	85	}
	86	}
	87
2344abbc TG	88	/**
	89	* clockevents_shutdown - shutdown the device and clear next_event
	90	* @dev: device to shutdown
	91	*/
	92	void clockevents_shutdown(struct clock_event_device *dev)
	93	{
	94	clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
	95	dev->next_event.tv64 = KTIME_MAX;
	96	}
	97
d316c57f TG	98	/**
	99	* clockevents_program_event - Reprogram the clock event device.
	100	* @expires: absolute expiry time (monotonic clock)
	101	*
	102	* Returns 0 on success, -ETIME when the event is in the past.
	103	*/
	104	int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
	105	ktime_t now)
	106	{
	107	unsigned long long clc;
	108	int64_t delta;
	109
167b1de3 TG	110	if (unlikely(expires.tv64 < 0)) {
	111	WARN_ON_ONCE(1);
	112	return -ETIME;
	113	}
	114
d316c57f TG	115	delta = ktime_to_ns(ktime_sub(expires, now));
	116
	117	if (delta <= 0)
	118	return -ETIME;
	119
	120	dev->next_event = expires;
	121
	122	if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
	123	return 0;
	124
	125	if (delta > dev->max_delta_ns)
	126	delta = dev->max_delta_ns;
	127	if (delta < dev->min_delta_ns)
	128	delta = dev->min_delta_ns;
	129
	130	clc = delta * dev->mult;
	131	clc >>= dev->shift;
	132
	133	return dev->set_next_event((unsigned long) clc, dev);
	134	}
	135
	136	/**
	137	* clockevents_register_notifier - register a clock events change listener
	138	*/
	139	int clockevents_register_notifier(struct notifier_block *nb)
	140	{
f833bab8	141	unsigned long flags;
d316c57f TG	142	int ret;
d316c57f TG	143
b5f91da0	144	raw_spin_lock_irqsave(&clockevents_lock, flags);
d316c57f	145	ret = raw_notifier_chain_register(&clockevents_chain, nb);
b5f91da0	146	raw_spin_unlock_irqrestore(&clockevents_lock, flags);
d316c57f TG	147
	148	return ret;
	149	}
	150
d316c57f TG	151	/*
	152	* Notify about a clock event change. Called with clockevents_lock
	153	* held.
	154	*/
	155	static void clockevents_do_notify(unsigned long reason, void *dev)
	156	{
	157	raw_notifier_call_chain(&clockevents_chain, reason, dev);
	158	}
	159
	160	/*
3eb05676	161	* Called after a notify add to make devices available which were
d316c57f TG	162	* released from the notifier call.
	163	*/
	164	static void clockevents_notify_released(void)
	165	{
	166	struct clock_event_device *dev;
	167
	168	while (!list_empty(&clockevents_released)) {
	169	dev = list_entry(clockevents_released.next,
	170	struct clock_event_device, list);
	171	list_del(&dev->list);
	172	list_add(&dev->list, &clockevent_devices);
	173	clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev);
	174	}
	175	}
	176
	177	/**
	178	* clockevents_register_device - register a clock event device
	179	* @dev: device to register
	180	*/
	181	void clockevents_register_device(struct clock_event_device *dev)
	182	{
f833bab8 SS	183	unsigned long flags;
f833bab8 SS	184
d316c57f	185	BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
320ab2b0 RR	186	BUG_ON(!dev->cpumask);
320ab2b0 RR	187
b5f91da0	188	raw_spin_lock_irqsave(&clockevents_lock, flags);
d316c57f TG	189
	190	list_add(&dev->list, &clockevent_devices);
	191	clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev);
	192	clockevents_notify_released();
	193
b5f91da0	194	raw_spin_unlock_irqrestore(&clockevents_lock, flags);
d316c57f	195	}
c81fc2c3	196	EXPORT_SYMBOL_GPL(clockevents_register_device);
d316c57f TG	197
	198	/*
	199	* Noop handler when we shut down an event device
	200	*/
7c1e7689	201	void clockevents_handle_noop(struct clock_event_device *dev)
d316c57f TG	202	{
	203	}
	204
	205	/**
	206	* clockevents_exchange_device - release and request clock devices
	207	* @old: device to release (can be NULL)
	208	* @new: device to request (can be NULL)
	209	*
	210	* Called from the notifier chain. clockevents_lock is held already
	211	*/
	212	void clockevents_exchange_device(struct clock_event_device *old,
	213	struct clock_event_device *new)
	214	{
	215	unsigned long flags;
	216
	217	local_irq_save(flags);
	218	/*
	219	* Caller releases a clock event device. We queue it into the
	220	* released list and do a notify add later.
	221	*/
	222	if (old) {
d316c57f TG	223	clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED);
	224	list_del(&old->list);
	225	list_add(&old->list, &clockevents_released);
	226	}
	227
	228	if (new) {
	229	BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED);
2344abbc	230	clockevents_shutdown(new);
d316c57f TG	231	}
	232	local_irq_restore(flags);
	233	}
	234
de68d9b1	235	#ifdef CONFIG_GENERIC_CLOCKEVENTS
d316c57f TG	236	/**
	237	* clockevents_notify - notification about relevant events
	238	*/
	239	void clockevents_notify(unsigned long reason, void *arg)
	240	{
bb6eddf7	241	struct clock_event_device dev, tmp;
f833bab8	242	unsigned long flags;
bb6eddf7	243	int cpu;
0b858e6f	244
b5f91da0	245	raw_spin_lock_irqsave(&clockevents_lock, flags);
d316c57f TG	246	clockevents_do_notify(reason, arg);
	247
	248	switch (reason) {
	249	case CLOCK_EVT_NOTIFY_CPU_DEAD:
	250	/*
	251	* Unregister the clock event devices which were
	252	* released from the users in the notify chain.
	253	*/
bb6eddf7 TG	254	list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
	255	list_del(&dev->list);
	256	/*
	257	* Now check whether the CPU has left unused per cpu devices
	258	*/
	259	cpu = ((int )arg);
	260	list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
	261	if (cpumask_test_cpu(cpu, dev->cpumask) &&
ea9d8e3f XF	262	cpumask_weight(dev->cpumask) == 1 &&
ea9d8e3f XF	263	!tick_is_broadcast_device(dev)) {
bb6eddf7 TG	264	BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
	265	list_del(&dev->list);
	266	}
	267	}
d316c57f TG	268	break;
	269	default:
	270	break;
	271	}
b5f91da0	272	raw_spin_unlock_irqrestore(&clockevents_lock, flags);
d316c57f TG	273	}
d316c57f TG	274	EXPORT_SYMBOL_GPL(clockevents_notify);
de68d9b1	275	#endif