[deliverable/linux.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>

/* 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_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)
 */
unsigned long 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 > LONG_MAX)
		clc = LONG_MAX;

	return (unsigned long) 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)
{
	int ret;

	spin_lock(&clockevents_lock);
	ret = raw_notifier_chain_register(&clockevents_chain, nb);
	spin_unlock(&clockevents_lock);

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

	spin_lock(&clockevents_lock);

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

	spin_unlock(&clockevents_lock);
}
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 list_head *node, *tmp;

	spin_lock(&clockevents_lock);
	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_safe(node, tmp, &clockevents_released)
			list_del(node);
		break;
	default:
		break;
	}
	spin_unlock(&clockevents_lock);
}
EXPORT_SYMBOL_GPL(clockevents_notify);

ktime_t clockevents_get_next_event(int cpu)
{
	struct tick_device *td;
	struct clock_event_device *dev;

	td = &per_cpu(tick_cpu_device, cpu);
	dev = td->evtdev;

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