[mirror_ubuntu-artful-kernel.git] / drivers / base / core.c

/*
 * drivers/base/core.c - core driver model code (device registration, etc)
 *
 * Copyright (c) 2002-3 Patrick Mochel
 * Copyright (c) 2002-3 Open Source Development Labs
 *
 * This file is released under the GPLv2
 *
 */

#include <linux/config.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>

#include <asm/semaphore.h>

#include "base.h"
#include "power/power.h"

int (*platform_notify)(struct device * dev) = NULL;
int (*platform_notify_remove)(struct device * dev) = NULL;

/*
 * sysfs bindings for devices.
 */

#define to_dev(obj) container_of(obj, struct device, kobj)
#define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)

static ssize_t
dev_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
{
	struct device_attribute * dev_attr = to_dev_attr(attr);
	struct device * dev = to_dev(kobj);
	ssize_t ret = -EIO;

	if (dev_attr->show)
		ret = dev_attr->show(dev, dev_attr, buf);
	return ret;
}

static ssize_t
dev_attr_store(struct kobject * kobj, struct attribute * attr,
	       const char * buf, size_t count)
{
	struct device_attribute * dev_attr = to_dev_attr(attr);
	struct device * dev = to_dev(kobj);
	ssize_t ret = -EIO;

	if (dev_attr->store)
		ret = dev_attr->store(dev, dev_attr, buf, count);
	return ret;
}

static struct sysfs_ops dev_sysfs_ops = {
	.show	= dev_attr_show,
	.store	= dev_attr_store,
};


/**
 *	device_release - free device structure.
 *	@kobj:	device's kobject.
 *
 *	This is called once the reference count for the object
 *	reaches 0. We forward the call to the device's release
 *	method, which should handle actually freeing the structure.
 */
static void device_release(struct kobject * kobj)
{
	struct device * dev = to_dev(kobj);

	if (dev->release)
		dev->release(dev);
	else {
		printk(KERN_ERR "Device '%s' does not have a release() function, "
			"it is broken and must be fixed.\n",
			dev->bus_id);
		WARN_ON(1);
	}
}

static struct kobj_type ktype_device = {
	.release	= device_release,
	.sysfs_ops	= &dev_sysfs_ops,
};


static int dev_hotplug_filter(struct kset *kset, struct kobject *kobj)
{
	struct kobj_type *ktype = get_ktype(kobj);

	if (ktype == &ktype_device) {
		struct device *dev = to_dev(kobj);
		if (dev->bus)
			return 1;
	}
	return 0;
}

static const char *dev_hotplug_name(struct kset *kset, struct kobject *kobj)
{
	struct device *dev = to_dev(kobj);

	return dev->bus->name;
}

static int dev_hotplug(struct kset *kset, struct kobject *kobj, char **envp,
			int num_envp, char *buffer, int buffer_size)
{
	struct device *dev = to_dev(kobj);
	int i = 0;
	int length = 0;
	int retval = 0;

	/* add bus name of physical device */
	if (dev->bus)
		add_hotplug_env_var(envp, num_envp, &i,
				    buffer, buffer_size, &length,
				    "PHYSDEVBUS=%s", dev->bus->name);

	/* add driver name of physical device */
	if (dev->driver)
		add_hotplug_env_var(envp, num_envp, &i,
				    buffer, buffer_size, &length,
				    "PHYSDEVDRIVER=%s", dev->driver->name);

	/* terminate, set to next free slot, shrink available space */
	envp[i] = NULL;
	envp = &envp[i];
	num_envp -= i;
	buffer = &buffer[length];
	buffer_size -= length;

	if (dev->bus && dev->bus->hotplug) {
		/* have the bus specific function add its stuff */
		retval = dev->bus->hotplug (dev, envp, num_envp, buffer, buffer_size);
			if (retval) {
			pr_debug ("%s - hotplug() returned %d\n",
				  __FUNCTION__, retval);
		}
	}

	return retval;
}

static struct kset_hotplug_ops device_hotplug_ops = {
	.filter =	dev_hotplug_filter,
	.name =		dev_hotplug_name,
	.hotplug =	dev_hotplug,
};

/**
 *	device_subsys - structure to be registered with kobject core.
 */

decl_subsys(devices, &ktype_device, &device_hotplug_ops);


/**
 *	device_create_file - create sysfs attribute file for device.
 *	@dev:	device.
 *	@attr:	device attribute descriptor.
 */

int device_create_file(struct device * dev, struct device_attribute * attr)
{
	int error = 0;
	if (get_device(dev)) {
		error = sysfs_create_file(&dev->kobj, &attr->attr);
		put_device(dev);
	}
	return error;
}

/**
 *	device_remove_file - remove sysfs attribute file.
 *	@dev:	device.
 *	@attr:	device attribute descriptor.
 */

void device_remove_file(struct device * dev, struct device_attribute * attr)
{
	if (get_device(dev)) {
		sysfs_remove_file(&dev->kobj, &attr->attr);
		put_device(dev);
	}
}

static void klist_children_get(struct klist_node *n)
{
	struct device *dev = container_of(n, struct device, knode_parent);

	get_device(dev);
}

static void klist_children_put(struct klist_node *n)
{
	struct device *dev = container_of(n, struct device, knode_parent);

	put_device(dev);
}


/**
 *	device_initialize - init device structure.
 *	@dev:	device.
 *
 *	This prepares the device for use by other layers,
 *	including adding it to the device hierarchy.
 *	It is the first half of device_register(), if called by
 *	that, though it can also be called separately, so one
 *	may use @dev's fields (e.g. the refcount).
 */

void device_initialize(struct device *dev)
{
	kobj_set_kset_s(dev, devices_subsys);
	kobject_init(&dev->kobj);
	klist_init(&dev->klist_children, klist_children_get,
		   klist_children_put);
	INIT_LIST_HEAD(&dev->dma_pools);
	init_MUTEX(&dev->sem);
}

/**
 *	device_add - add device to device hierarchy.
 *	@dev:	device.
 *
 *	This is part 2 of device_register(), though may be called
 *	separately _iff_ device_initialize() has been called separately.
 *
 *	This adds it to the kobject hierarchy via kobject_add(), adds it
 *	to the global and sibling lists for the device, then
 *	adds it to the other relevant subsystems of the driver model.
 */
int device_add(struct device *dev)
{
	struct device *parent = NULL;
	int error = -EINVAL;

	dev = get_device(dev);
	if (!dev || !strlen(dev->bus_id))
		goto Error;

	parent = get_device(dev->parent);

	pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id);

	/* first, register with generic layer. */
	kobject_set_name(&dev->kobj, "%s", dev->bus_id);
	if (parent)
		dev->kobj.parent = &parent->kobj;

	if ((error = kobject_add(&dev->kobj)))
		goto Error;
	kobject_hotplug(&dev->kobj, KOBJ_ADD);
	if ((error = device_pm_add(dev)))
		goto PMError;
	if ((error = bus_add_device(dev)))
		goto BusError;
	if (parent)
		klist_add_tail(&dev->knode_parent, &parent->klist_children);

	/* notify platform of device entry */
	if (platform_notify)
		platform_notify(dev);
 Done:
	put_device(dev);
	return error;
 BusError:
	device_pm_remove(dev);
 PMError:
	kobject_hotplug(&dev->kobj, KOBJ_REMOVE);
	kobject_del(&dev->kobj);
 Error:
	if (parent)
		put_device(parent);
	goto Done;
}


/**
 *	device_register - register a device with the system.
 *	@dev:	pointer to the device structure
 *
 *	This happens in two clean steps - initialize the device
 *	and add it to the system. The two steps can be called
 *	separately, but this is the easiest and most common.
 *	I.e. you should only call the two helpers separately if
 *	have a clearly defined need to use and refcount the device
 *	before it is added to the hierarchy.
 */

int device_register(struct device *dev)
{
	device_initialize(dev);
	return device_add(dev);
}


/**
 *	get_device - increment reference count for device.
 *	@dev:	device.
 *
 *	This simply forwards the call to kobject_get(), though
 *	we do take care to provide for the case that we get a NULL
 *	pointer passed in.
 */

struct device * get_device(struct device * dev)
{
	return dev ? to_dev(kobject_get(&dev->kobj)) : NULL;
}


/**
 *	put_device - decrement reference count.
 *	@dev:	device in question.
 */
void put_device(struct device * dev)
{
	if (dev)
		kobject_put(&dev->kobj);
}


/**
 *	device_del - delete device from system.
 *	@dev:	device.
 *
 *	This is the first part of the device unregistration
 *	sequence. This removes the device from the lists we control
 *	from here, has it removed from the other driver model
 *	subsystems it was added to in device_add(), and removes it
 *	from the kobject hierarchy.
 *
 *	NOTE: this should be called manually _iff_ device_add() was
 *	also called manually.
 */

void device_del(struct device * dev)
{
	struct device * parent = dev->parent;

	if (parent)
		klist_del(&dev->knode_parent);

	/* Notify the platform of the removal, in case they
	 * need to do anything...
	 */
	if (platform_notify_remove)
		platform_notify_remove(dev);
	bus_remove_device(dev);
	device_pm_remove(dev);
	kobject_hotplug(&dev->kobj, KOBJ_REMOVE);
	kobject_del(&dev->kobj);
	if (parent)
		put_device(parent);
}

/**
 *	device_unregister - unregister device from system.
 *	@dev:	device going away.
 *
 *	We do this in two parts, like we do device_register(). First,
 *	we remove it from all the subsystems with device_del(), then
 *	we decrement the reference count via put_device(). If that
 *	is the final reference count, the device will be cleaned up
 *	via device_release() above. Otherwise, the structure will
 *	stick around until the final reference to the device is dropped.
 */
void device_unregister(struct device * dev)
{
	pr_debug("DEV: Unregistering device. ID = '%s'\n", dev->bus_id);
	device_del(dev);
	put_device(dev);
}


static struct device * next_device(struct klist_iter * i)
{
	struct klist_node * n = klist_next(i);
	return n ? container_of(n, struct device, knode_parent) : NULL;
}

/**
 *	device_for_each_child - device child iterator.
 *	@dev:	parent struct device.
 *	@data:	data for the callback.
 *	@fn:	function to be called for each device.
 *
 *	Iterate over @dev's child devices, and call @fn for each,
 *	passing it @data.
 *
 *	We check the return of @fn each time. If it returns anything
 *	other than 0, we break out and return that value.
 */
int device_for_each_child(struct device * parent, void * data,
		     int (*fn)(struct device *, void *))
{
	struct klist_iter i;
	struct device * child;
	int error = 0;

	klist_iter_init(&parent->klist_children, &i);
	while ((child = next_device(&i)) && !error)
		error = fn(child, data);
	klist_iter_exit(&i);
	return error;
}

int __init devices_init(void)
{
	return subsystem_register(&devices_subsys);
}

EXPORT_SYMBOL_GPL(device_for_each_child);

EXPORT_SYMBOL_GPL(device_initialize);
EXPORT_SYMBOL_GPL(device_add);
EXPORT_SYMBOL_GPL(device_register);

EXPORT_SYMBOL_GPL(device_del);
EXPORT_SYMBOL_GPL(device_unregister);
EXPORT_SYMBOL_GPL(get_device);
EXPORT_SYMBOL_GPL(put_device);

EXPORT_SYMBOL_GPL(device_create_file);
EXPORT_SYMBOL_GPL(device_remove_file);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* drivers/base/core.c - core driver model code (device registration, etc)
	3	*
	4	* Copyright (c) 2002-3 Patrick Mochel
	5	* Copyright (c) 2002-3 Open Source Development Labs
	6	*
	7	* This file is released under the GPLv2
	8	*
	9	*/
	10
	11	#include <linux/config.h>
	12	#include <linux/device.h>
	13	#include <linux/err.h>
	14	#include <linux/init.h>
	15	#include <linux/module.h>
	16	#include <linux/slab.h>
	17	#include <linux/string.h>
	18
	19	#include <asm/semaphore.h>
	20
	21	#include "base.h"
	22	#include "power/power.h"
	23
	24	int (platform_notify)(struct device dev) = NULL;
	25	int (platform_notify_remove)(struct device dev) = NULL;
	26
	27	/*
	28	* sysfs bindings for devices.
	29	*/
	30
	31	#define to_dev(obj) container_of(obj, struct device, kobj)
	32	#define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
	33
1da177e4 LT	34	static ssize_t
	35	dev_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
	36	{
	37	struct device_attribute * dev_attr = to_dev_attr(attr);
	38	struct device * dev = to_dev(kobj);
4a0c20bf	39	ssize_t ret = -EIO;
1da177e4 LT	40
1da177e4 LT	41	if (dev_attr->show)
54b6f35c	42	ret = dev_attr->show(dev, dev_attr, buf);
1da177e4 LT	43	return ret;
	44	}
	45
	46	static ssize_t
	47	dev_attr_store(struct kobject * kobj, struct attribute * attr,
	48	const char * buf, size_t count)
	49	{
	50	struct device_attribute * dev_attr = to_dev_attr(attr);
	51	struct device * dev = to_dev(kobj);
4a0c20bf	52	ssize_t ret = -EIO;
1da177e4 LT	53
1da177e4 LT	54	if (dev_attr->store)
54b6f35c	55	ret = dev_attr->store(dev, dev_attr, buf, count);
1da177e4 LT	56	return ret;
	57	}
	58
	59	static struct sysfs_ops dev_sysfs_ops = {
	60	.show = dev_attr_show,
	61	.store = dev_attr_store,
	62	};
	63
	64
	65	/**
	66	* device_release - free device structure.
	67	* @kobj: device's kobject.
	68	*
	69	* This is called once the reference count for the object
	70	* reaches 0. We forward the call to the device's release
	71	* method, which should handle actually freeing the structure.
	72	*/
	73	static void device_release(struct kobject * kobj)
	74	{
	75	struct device * dev = to_dev(kobj);
	76
	77	if (dev->release)
	78	dev->release(dev);
	79	else {
	80	printk(KERN_ERR "Device '%s' does not have a release() function, "
	81	"it is broken and must be fixed.\n",
	82	dev->bus_id);
	83	WARN_ON(1);
	84	}
	85	}
	86
	87	static struct kobj_type ktype_device = {
	88	.release = device_release,
	89	.sysfs_ops = &dev_sysfs_ops,
1da177e4 LT	90	};
	91
	92
	93	static int dev_hotplug_filter(struct kset kset, struct kobject kobj)
	94	{
	95	struct kobj_type *ktype = get_ktype(kobj);
	96
	97	if (ktype == &ktype_device) {
	98	struct device *dev = to_dev(kobj);
	99	if (dev->bus)
	100	return 1;
	101	}
	102	return 0;
	103	}
	104
419cab3f	105	static const char dev_hotplug_name(struct kset kset, struct kobject *kobj)
1da177e4 LT	106	{
	107	struct device *dev = to_dev(kobj);
	108
	109	return dev->bus->name;
	110	}
	111
	112	static int dev_hotplug(struct kset kset, struct kobject kobj, char **envp,
	113	int num_envp, char *buffer, int buffer_size)
	114	{
	115	struct device *dev = to_dev(kobj);
	116	int i = 0;
	117	int length = 0;
	118	int retval = 0;
	119
	120	/* add bus name of physical device */
	121	if (dev->bus)
	122	add_hotplug_env_var(envp, num_envp, &i,
	123	buffer, buffer_size, &length,
	124	"PHYSDEVBUS=%s", dev->bus->name);
	125
	126	/* add driver name of physical device */
	127	if (dev->driver)
	128	add_hotplug_env_var(envp, num_envp, &i,
	129	buffer, buffer_size, &length,
	130	"PHYSDEVDRIVER=%s", dev->driver->name);
	131
	132	/* terminate, set to next free slot, shrink available space */
	133	envp[i] = NULL;
	134	envp = &envp[i];
	135	num_envp -= i;
	136	buffer = &buffer[length];
	137	buffer_size -= length;
	138
177a4324	139	if (dev->bus && dev->bus->hotplug) {
1da177e4 LT	140	/* have the bus specific function add its stuff */
	141	retval = dev->bus->hotplug (dev, envp, num_envp, buffer, buffer_size);
	142	if (retval) {
	143	pr_debug ("%s - hotplug() returned %d\n",
	144	__FUNCTION__, retval);
	145	}
	146	}
	147
	148	return retval;
	149	}
	150
	151	static struct kset_hotplug_ops device_hotplug_ops = {
	152	.filter = dev_hotplug_filter,
	153	.name = dev_hotplug_name,
	154	.hotplug = dev_hotplug,
	155	};
	156
	157	/**
	158	* device_subsys - structure to be registered with kobject core.
	159	*/
	160
	161	decl_subsys(devices, &ktype_device, &device_hotplug_ops);
	162
	163
	164	/**
	165	* device_create_file - create sysfs attribute file for device.
	166	* @dev: device.
	167	* @attr: device attribute descriptor.
	168	*/
	169
	170	int device_create_file(struct device * dev, struct device_attribute * attr)
	171	{
	172	int error = 0;
	173	if (get_device(dev)) {
	174	error = sysfs_create_file(&dev->kobj, &attr->attr);
	175	put_device(dev);
	176	}
	177	return error;
	178	}
	179
	180	/**
	181	* device_remove_file - remove sysfs attribute file.
	182	* @dev: device.
	183	* @attr: device attribute descriptor.
	184	*/
	185
	186	void device_remove_file(struct device * dev, struct device_attribute * attr)
	187	{
	188	if (get_device(dev)) {
	189	sysfs_remove_file(&dev->kobj, &attr->attr);
	190	put_device(dev);
	191	}
	192	}
	193
34bb61f9 JB	194	static void klist_children_get(struct klist_node *n)
	195	{
	196	struct device *dev = container_of(n, struct device, knode_parent);
	197
	198	get_device(dev);
	199	}
	200
	201	static void klist_children_put(struct klist_node *n)
	202	{
	203	struct device *dev = container_of(n, struct device, knode_parent);
	204
	205	put_device(dev);
	206	}
	207
1da177e4 LT	208
	209	/**
	210	* device_initialize - init device structure.
	211	* @dev: device.
	212	*
	213	* This prepares the device for use by other layers,
	214	* including adding it to the device hierarchy.
	215	* It is the first half of device_register(), if called by
	216	* that, though it can also be called separately, so one
	217	* may use @dev's fields (e.g. the refcount).
	218	*/
	219
	220	void device_initialize(struct device *dev)
	221	{
	222	kobj_set_kset_s(dev, devices_subsys);
	223	kobject_init(&dev->kobj);
34bb61f9 JB	224	klist_init(&dev->klist_children, klist_children_get,
34bb61f9 JB	225	klist_children_put);
1da177e4	226	INIT_LIST_HEAD(&dev->dma_pools);
af70316a	227	init_MUTEX(&dev->sem);
1da177e4 LT	228	}
	229
	230	/**
	231	* device_add - add device to device hierarchy.
	232	* @dev: device.
	233	*
	234	* This is part 2 of device_register(), though may be called
	235	* separately _iff_ device_initialize() has been called separately.
	236	*
	237	* This adds it to the kobject hierarchy via kobject_add(), adds it
	238	* to the global and sibling lists for the device, then
	239	* adds it to the other relevant subsystems of the driver model.
	240	*/
	241	int device_add(struct device *dev)
	242	{
	243	struct device *parent = NULL;
	244	int error = -EINVAL;
	245
	246	dev = get_device(dev);
	247	if (!dev \|\| !strlen(dev->bus_id))
	248	goto Error;
	249
	250	parent = get_device(dev->parent);
	251
	252	pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id);
	253
	254	/* first, register with generic layer. */
	255	kobject_set_name(&dev->kobj, "%s", dev->bus_id);
	256	if (parent)
	257	dev->kobj.parent = &parent->kobj;
	258
	259	if ((error = kobject_add(&dev->kobj)))
	260	goto Error;
187a1a94	261	kobject_hotplug(&dev->kobj, KOBJ_ADD);
1da177e4 LT	262	if ((error = device_pm_add(dev)))
	263	goto PMError;
	264	if ((error = bus_add_device(dev)))
	265	goto BusError;
1da177e4	266	if (parent)
d856f1e3	267	klist_add_tail(&dev->knode_parent, &parent->klist_children);
1da177e4 LT	268
	269	/* notify platform of device entry */
	270	if (platform_notify)
	271	platform_notify(dev);
	272	Done:
	273	put_device(dev);
	274	return error;
	275	BusError:
	276	device_pm_remove(dev);
	277	PMError:
187a1a94	278	kobject_hotplug(&dev->kobj, KOBJ_REMOVE);
1da177e4 LT	279	kobject_del(&dev->kobj);
	280	Error:
	281	if (parent)
	282	put_device(parent);
	283	goto Done;
	284	}
	285
	286
	287	/**
	288	* device_register - register a device with the system.
	289	* @dev: pointer to the device structure
	290	*
	291	* This happens in two clean steps - initialize the device
	292	* and add it to the system. The two steps can be called
	293	* separately, but this is the easiest and most common.
	294	* I.e. you should only call the two helpers separately if
	295	* have a clearly defined need to use and refcount the device
	296	* before it is added to the hierarchy.
	297	*/
	298
	299	int device_register(struct device *dev)
	300	{
	301	device_initialize(dev);
	302	return device_add(dev);
	303	}
	304
	305
	306	/**
	307	* get_device - increment reference count for device.
	308	* @dev: device.
	309	*
	310	* This simply forwards the call to kobject_get(), though
	311	* we do take care to provide for the case that we get a NULL
	312	* pointer passed in.
	313	*/
	314
	315	struct device * get_device(struct device * dev)
	316	{
	317	return dev ? to_dev(kobject_get(&dev->kobj)) : NULL;
	318	}
	319
	320
	321	/**
	322	* put_device - decrement reference count.
	323	* @dev: device in question.
	324	*/
	325	void put_device(struct device * dev)
	326	{
	327	if (dev)
	328	kobject_put(&dev->kobj);
	329	}
	330
	331
	332	/**
	333	* device_del - delete device from system.
	334	* @dev: device.
	335	*
	336	* This is the first part of the device unregistration
	337	* sequence. This removes the device from the lists we control
	338	* from here, has it removed from the other driver model
	339	* subsystems it was added to in device_add(), and removes it
	340	* from the kobject hierarchy.
	341	*
	342	* NOTE: this should be called manually _iff_ device_add() was
343	* also called manually.
344	*/
345
346	void device_del(struct device * dev)
347	{
348	struct device * parent = dev->parent;
349
1da177e4	350	if (parent)
d62c0f9f	351	klist_del(&dev->knode_parent);
1da177e4 LT	352
	353	/* Notify the platform of the removal, in case they
	354	* need to do anything...
	355	*/
	356	if (platform_notify_remove)
	357	platform_notify_remove(dev);
	358	bus_remove_device(dev);
	359	device_pm_remove(dev);
e57cd73e	360	kobject_hotplug(&dev->kobj, KOBJ_REMOVE);
1da177e4 LT	361	kobject_del(&dev->kobj);
	362	if (parent)
	363	put_device(parent);
	364	}
	365
	366	/**
	367	* device_unregister - unregister device from system.
	368	* @dev: device going away.
	369	*
	370	* We do this in two parts, like we do device_register(). First,
	371	* we remove it from all the subsystems with device_del(), then
	372	* we decrement the reference count via put_device(). If that
	373	* is the final reference count, the device will be cleaned up
	374	* via device_release() above. Otherwise, the structure will
	375	* stick around until the final reference to the device is dropped.
	376	*/
	377	void device_unregister(struct device * dev)
	378	{
	379	pr_debug("DEV: Unregistering device. ID = '%s'\n", dev->bus_id);
	380	device_del(dev);
	381	put_device(dev);
	382	}
	383
	384
36239577 PM	385	static struct device * next_device(struct klist_iter * i)
	386	{
	387	struct klist_node * n = klist_next(i);
	388	return n ? container_of(n, struct device, knode_parent) : NULL;
	389	}
	390
1da177e4 LT	391	/**
	392	* device_for_each_child - device child iterator.
	393	* @dev: parent struct device.
	394	* @data: data for the callback.
	395	* @fn: function to be called for each device.
	396	*
	397	* Iterate over @dev's child devices, and call @fn for each,
	398	* passing it @data.
	399	*
	400	* We check the return of @fn each time. If it returns anything
	401	* other than 0, we break out and return that value.
	402	*/
36239577	403	int device_for_each_child(struct device * parent, void * data,
1da177e4 LT	404	int (fn)(struct device , void *))
1da177e4 LT	405	{
36239577	406	struct klist_iter i;
1da177e4 LT	407	struct device * child;
	408	int error = 0;
	409
36239577 PM	410	klist_iter_init(&parent->klist_children, &i);
	411	while ((child = next_device(&i)) && !error)
	412	error = fn(child, data);
	413	klist_iter_exit(&i);
1da177e4 LT	414	return error;
	415	}
	416
1da177e4 LT	417	int __init devices_init(void)
	418	{
	419	return subsystem_register(&devices_subsys);
	420	}
	421
	422	EXPORT_SYMBOL_GPL(device_for_each_child);
	423
	424	EXPORT_SYMBOL_GPL(device_initialize);
	425	EXPORT_SYMBOL_GPL(device_add);
	426	EXPORT_SYMBOL_GPL(device_register);
	427
	428	EXPORT_SYMBOL_GPL(device_del);
	429	EXPORT_SYMBOL_GPL(device_unregister);
	430	EXPORT_SYMBOL_GPL(get_device);
	431	EXPORT_SYMBOL_GPL(put_device);
1da177e4 LT	432
	433	EXPORT_SYMBOL_GPL(device_create_file);
	434	EXPORT_SYMBOL_GPL(device_remove_file);