kernel/time/clockevents.c - maze/linux - Git at Google

 /*
  * 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>

 /* 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);

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

 	return (unsigned long) clc;
 }

 /**
  * 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;
 	}
 }

 /**
  * 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;

 	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;
 }

 /**
  * clockevents_unregister_notifier - unregister a clock events change listener
  */
 void clockevents_unregister_notifier(struct notifier_block *nb)
 {
 	spin_lock(&clockevents_lock);
 	raw_notifier_chain_unregister(&clockevents_chain, nb);
 	spin_unlock(&clockevents_lock);
 }

 /*
  * 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 availble 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);

 	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);
 }

 /*
  * Noop handler when we shut down an event device
  */
 static 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) {
 		old->event_handler = clockevents_handle_noop;
 		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_set_mode(new, CLOCK_EVT_MODE_SHUTDOWN);
 	}
 	local_irq_restore(flags);
 }

 /**
  * clockevents_request_device
  */
 struct clock_event_device *clockevents_request_device(unsigned int features,
 						      cpumask_t cpumask)
 {
 	struct clock_event_device *cur, *dev = NULL;
 	struct list_head *tmp;

 	spin_lock(&clockevents_lock);

 	list_for_each(tmp, &clockevent_devices) {
 		cur = list_entry(tmp, struct clock_event_device, list);

 		if ((cur->features & features) == features &&
 		    cpus_equal(cpumask, cur->cpumask)) {
 			if (!dev || dev->rating < cur->rating)
 				dev = cur;
 		}
 	}

 	clockevents_exchange_device(NULL, dev);

 	spin_unlock(&clockevents_lock);

 	return dev;
 }

 /**
  * clockevents_release_device
  */
 void clockevents_release_device(struct clock_event_device *dev)
 {
 	spin_lock(&clockevents_lock);

 	clockevents_exchange_device(dev, NULL);
 	clockevents_notify_released();

 	spin_unlock(&clockevents_lock);
 }

 /**
  * clockevents_notify - notification about relevant events
  */
 void clockevents_notify(unsigned long reason, void *arg)
 {
 	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.
 		 */
 		while (!list_empty(&clockevents_released)) {
 			struct clock_event_device *dev;

 			dev = list_entry(clockevents_released.next,
 					 struct clock_event_device, list);
 			list_del(&dev->list);
 		}
 		break;
 	default:
 		break;
 	}
 	spin_unlock(&clockevents_lock);
 }
 EXPORT_SYMBOL_GPL(clockevents_notify);

 #ifdef CONFIG_SYSFS

 /**
  * clockevents_show_registered - sysfs interface for listing clockevents
  * @dev:	unused
  * @buf:	char buffer to be filled with clock events list
  *
  * Provides sysfs interface for listing registered clock event devices
  */
 static ssize_t clockevents_show_registered(struct sys_device *dev, char *buf)
 {
 	struct list_head *tmp;
 	char *p = buf;
 	int cpu;

 	spin_lock(&clockevents_lock);

 	list_for_each(tmp, &clockevent_devices) {
 		struct clock_event_device *ce;

 		ce = list_entry(tmp, struct clock_event_device, list);
 		p += sprintf(p, "%-20s F:%04x M:%d", ce->name,
 			     ce->features, ce->mode);
 		p += sprintf(p, " C:");
 		if (!cpus_equal(ce->cpumask, cpu_possible_map)) {
 			for_each_cpu_mask(cpu, ce->cpumask)
 				p += sprintf(p, " %d", cpu);
 		} else {
 			/*
 			 * FIXME: Add the cpu which is handling this sucker
 			 */
 		}
 		p += sprintf(p, "\n");
 	}

 	spin_unlock(&clockevents_lock);

 	return p - buf;
 }

 /*
  * Sysfs setup bits:
  */
 static SYSDEV_ATTR(registered, 0600,
 		   clockevents_show_registered, NULL);

 static struct sysdev_class clockevents_sysclass = {
 	set_kset_name("clockevents"),
 };

 static struct sys_device clockevents_sys_device = {
 	.id	= 0,
 	.cls	= &clockevents_sysclass,
 };

 static int __init clockevents_sysfs_init(void)
 {
 	int error = sysdev_class_register(&clockevents_sysclass);

 	if (!error)
 		error = sysdev_register(&clockevents_sys_device);
 	if (!error)
 		error = sysdev_create_file(
 				&clockevents_sys_device,
 				&attr_registered);
 	return error;
 }
 device_initcall(clockevents_sysfs_init);
 #endif
	/*
	* 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>

	/* 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);

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

	return (unsigned long) clc;
	}

	/**
	* 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;
	}
	}

	/**
	* 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;

	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;
	}

	/**
	* clockevents_unregister_notifier - unregister a clock events change listener
	*/
	void clockevents_unregister_notifier(struct notifier_block *nb)
	{
	spin_lock(&clockevents_lock);
	raw_notifier_chain_unregister(&clockevents_chain, nb);
	spin_unlock(&clockevents_lock);
	}

	/*
	* 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 availble 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);

	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);
	}

	/*
	* Noop handler when we shut down an event device
	*/
	static 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) {
	old->event_handler = clockevents_handle_noop;
	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_set_mode(new, CLOCK_EVT_MODE_SHUTDOWN);
	}
	local_irq_restore(flags);
	}

	/**
	* clockevents_request_device
	*/
	struct clock_event_device *clockevents_request_device(unsigned int features,
	cpumask_t cpumask)
	{
	struct clock_event_device cur, dev = NULL;
	struct list_head *tmp;

	spin_lock(&clockevents_lock);

	list_for_each(tmp, &clockevent_devices) {
	cur = list_entry(tmp, struct clock_event_device, list);

	if ((cur->features & features) == features &&
	cpus_equal(cpumask, cur->cpumask)) {
	if (!dev \|\| dev->rating < cur->rating)
	dev = cur;
	}
	}

	clockevents_exchange_device(NULL, dev);

	spin_unlock(&clockevents_lock);

	return dev;
	}

	/**
	* clockevents_release_device
	*/
	void clockevents_release_device(struct clock_event_device *dev)
	{
	spin_lock(&clockevents_lock);

	clockevents_exchange_device(dev, NULL);
	clockevents_notify_released();

	spin_unlock(&clockevents_lock);
	}

	/**
	* clockevents_notify - notification about relevant events
	*/
	void clockevents_notify(unsigned long reason, void *arg)
	{
	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.
	*/
	while (!list_empty(&clockevents_released)) {
	struct clock_event_device *dev;

	dev = list_entry(clockevents_released.next,
	struct clock_event_device, list);
	list_del(&dev->list);
	}
	break;
	default:
	break;
	}
	spin_unlock(&clockevents_lock);
	}
	EXPORT_SYMBOL_GPL(clockevents_notify);

	#ifdef CONFIG_SYSFS

	/**
	* clockevents_show_registered - sysfs interface for listing clockevents
	* @dev: unused
	* @buf: char buffer to be filled with clock events list
	*
	* Provides sysfs interface for listing registered clock event devices
	*/
	static ssize_t clockevents_show_registered(struct sys_device dev, char buf)
	{
	struct list_head *tmp;
	char *p = buf;
	int cpu;

	spin_lock(&clockevents_lock);

	list_for_each(tmp, &clockevent_devices) {
	struct clock_event_device *ce;

	ce = list_entry(tmp, struct clock_event_device, list);
	p += sprintf(p, "%-20s F:%04x M:%d", ce->name,
	ce->features, ce->mode);
	p += sprintf(p, " C:");
	if (!cpus_equal(ce->cpumask, cpu_possible_map)) {
	for_each_cpu_mask(cpu, ce->cpumask)
	p += sprintf(p, " %d", cpu);
	} else {
	/*
	* FIXME: Add the cpu which is handling this sucker
	*/
	}
	p += sprintf(p, "\n");
	}

	spin_unlock(&clockevents_lock);

	return p - buf;
	}

	/*
	* Sysfs setup bits:
	*/
	static SYSDEV_ATTR(registered, 0600,
	clockevents_show_registered, NULL);

	static struct sysdev_class clockevents_sysclass = {
	set_kset_name("clockevents"),
	};

	static struct sys_device clockevents_sys_device = {
	.id = 0,
	.cls = &clockevents_sysclass,
	};

	static int __init clockevents_sysfs_init(void)
	{
	int error = sysdev_class_register(&clockevents_sysclass);

	if (!error)
	error = sysdev_register(&clockevents_sys_device);
	if (!error)
	error = sysdev_create_file(
	&clockevents_sys_device,
	&attr_registered);
	return error;
	}
	device_initcall(clockevents_sysfs_init);
	#endif