/*
   * 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

   * Copyright (c) 2006 Greg Kroah-Hartman <gregkh@suse.de>
   * Copyright (c) 2006 Novell, Inc.

   *
   * This file is released under the GPLv2
   *
   */

  #include <linux/device.h>
  #include <linux/err.h>

  #include <linux/fwnode.h>

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

  #include <linux/kdev_t.h>

  #include <linux/notifier.h>

  #include <linux/of.h>
  #include <linux/of_device.h>

  #include <linux/genhd.h>

  #include <linux/kallsyms.h>

  #include <linux/mutex.h>

  #include <linux/pm_runtime.h>

  #include <linux/netdevice.h>

  #include <linux/sysfs.h>

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

  #ifdef CONFIG_SYSFS_DEPRECATED
  #ifdef CONFIG_SYSFS_DEPRECATED_V2
  long sysfs_deprecated = 1;
  #else
  long sysfs_deprecated = 0;
  #endif

  static int __init sysfs_deprecated_setup(char *arg)

  {

  	return kstrtol(arg, 10, &sysfs_deprecated);

  }
  early_param("sysfs.deprecated", sysfs_deprecated_setup);
  #endif

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

  static struct kobject *dev_kobj;
  struct kobject *sysfs_dev_char_kobj;
  struct kobject *sysfs_dev_block_kobj;

  static DEFINE_MUTEX(device_hotplug_lock);
  
  void lock_device_hotplug(void)
  {
  	mutex_lock(&device_hotplug_lock);
  }
  
  void unlock_device_hotplug(void)
  {
  	mutex_unlock(&device_hotplug_lock);
  }
  
  int lock_device_hotplug_sysfs(void)
  {
  	if (mutex_trylock(&device_hotplug_lock))
  		return 0;
  
  	/* Avoid busy looping (5 ms of sleep should do). */
  	msleep(5);
  	return restart_syscall();
  }

  #ifdef CONFIG_BLOCK
  static inline int device_is_not_partition(struct device *dev)
  {
  	return !(dev->type == &part_type);
  }
  #else
  static inline int device_is_not_partition(struct device *dev)
  {
  	return 1;
  }
  #endif

  /**
   * dev_driver_string - Return a device's driver name, if at all possible
   * @dev: struct device to get the name of
   *
   * Will return the device's driver's name if it is bound to a device.  If

   * the device is not bound to a driver, it will return the name of the bus

   * it is attached to.  If it is not attached to a bus either, an empty
   * string will be returned.
   */

  const char *dev_driver_string(const struct device *dev)

  {

  	struct device_driver *drv;
  
  	/* dev->driver can change to NULL underneath us because of unbinding,
  	 * so be careful about accessing it.  dev->bus and dev->class should
  	 * never change once they are set, so they don't need special care.
  	 */
  	drv = ACCESS_ONCE(dev->driver);
  	return drv ? drv->name :

  			(dev->bus ? dev->bus->name :
  			(dev->class ? dev->class->name : ""));

  }

  EXPORT_SYMBOL(dev_driver_string);

  #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 = kobj_to_dev(kobj);

  	ssize_t ret = -EIO;

  
  	if (dev_attr->show)

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

  	if (ret >= (ssize_t)PAGE_SIZE) {

  		print_symbol("dev_attr_show: %s returned bad count
  ",
  				(unsigned long)dev_attr->show);

  	}

  	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 = kobj_to_dev(kobj);

  	ssize_t ret = -EIO;

  
  	if (dev_attr->store)

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

  	return ret;
  }

  static const struct sysfs_ops dev_sysfs_ops = {

  	.show	= dev_attr_show,
  	.store	= dev_attr_store,
  };

  #define to_ext_attr(x) container_of(x, struct dev_ext_attribute, attr)
  
  ssize_t device_store_ulong(struct device *dev,
  			   struct device_attribute *attr,
  			   const char *buf, size_t size)
  {
  	struct dev_ext_attribute *ea = to_ext_attr(attr);
  	char *end;
  	unsigned long new = simple_strtoul(buf, &end, 0);
  	if (end == buf)
  		return -EINVAL;
  	*(unsigned long *)(ea->var) = new;
  	/* Always return full write size even if we didn't consume all */
  	return size;
  }
  EXPORT_SYMBOL_GPL(device_store_ulong);
  
  ssize_t device_show_ulong(struct device *dev,
  			  struct device_attribute *attr,
  			  char *buf)
  {
  	struct dev_ext_attribute *ea = to_ext_attr(attr);
  	return snprintf(buf, PAGE_SIZE, "%lx
  ", *(unsigned long *)(ea->var));
  }
  EXPORT_SYMBOL_GPL(device_show_ulong);
  
  ssize_t device_store_int(struct device *dev,
  			 struct device_attribute *attr,
  			 const char *buf, size_t size)
  {
  	struct dev_ext_attribute *ea = to_ext_attr(attr);
  	char *end;
  	long new = simple_strtol(buf, &end, 0);
  	if (end == buf || new > INT_MAX || new < INT_MIN)
  		return -EINVAL;
  	*(int *)(ea->var) = new;
  	/* Always return full write size even if we didn't consume all */
  	return size;
  }
  EXPORT_SYMBOL_GPL(device_store_int);
  
  ssize_t device_show_int(struct device *dev,
  			struct device_attribute *attr,
  			char *buf)
  {
  	struct dev_ext_attribute *ea = to_ext_attr(attr);
  
  	return snprintf(buf, PAGE_SIZE, "%d
  ", *(int *)(ea->var));
  }
  EXPORT_SYMBOL_GPL(device_show_int);

  ssize_t device_store_bool(struct device *dev, struct device_attribute *attr,
  			  const char *buf, size_t size)
  {
  	struct dev_ext_attribute *ea = to_ext_attr(attr);
  
  	if (strtobool(buf, ea->var) < 0)
  		return -EINVAL;
  
  	return size;
  }
  EXPORT_SYMBOL_GPL(device_store_bool);
  
  ssize_t device_show_bool(struct device *dev, struct device_attribute *attr,
  			 char *buf)
  {
  	struct dev_ext_attribute *ea = to_ext_attr(attr);
  
  	return snprintf(buf, PAGE_SIZE, "%d
  ", *(bool *)(ea->var));
  }
  EXPORT_SYMBOL_GPL(device_show_bool);

  /**

   * 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 = kobj_to_dev(kobj);

  	struct device_private *p = dev->p;

  	/*
  	 * Some platform devices are driven without driver attached
  	 * and managed resources may have been acquired.  Make sure
  	 * all resources are released.
  	 *
  	 * Drivers still can add resources into device after device
  	 * is deleted but alive, so release devres here to avoid
  	 * possible memory leak.
  	 */
  	devres_release_all(dev);

  	if (dev->release)
  		dev->release(dev);

  	else if (dev->type && dev->type->release)
  		dev->type->release(dev);

  	else if (dev->class && dev->class->dev_release)
  		dev->class->dev_release(dev);

  	else
  		WARN(1, KERN_ERR "Device '%s' does not have a release() "

  			"function, it is broken and must be fixed.
  ",

  			dev_name(dev));

  	kfree(p);

  }

  static const void *device_namespace(struct kobject *kobj)
  {

  	struct device *dev = kobj_to_dev(kobj);

  	const void *ns = NULL;
  
  	if (dev->class && dev->class->ns_type)
  		ns = dev->class->namespace(dev);
  
  	return ns;
  }

  static struct kobj_type device_ktype = {

  	.release	= device_release,
  	.sysfs_ops	= &dev_sysfs_ops,

  	.namespace	= device_namespace,

  };

  static int dev_uevent_filter(struct kset *kset, struct kobject *kobj)

  {
  	struct kobj_type *ktype = get_ktype(kobj);

  	if (ktype == &device_ktype) {

  		struct device *dev = kobj_to_dev(kobj);

  		if (dev->bus)
  			return 1;

  		if (dev->class)
  			return 1;

  	}
  	return 0;
  }

  static const char *dev_uevent_name(struct kset *kset, struct kobject *kobj)

  {

  	struct device *dev = kobj_to_dev(kobj);

  	if (dev->bus)
  		return dev->bus->name;
  	if (dev->class)
  		return dev->class->name;
  	return NULL;

  }

  static int dev_uevent(struct kset *kset, struct kobject *kobj,
  		      struct kobj_uevent_env *env)

  {

  	struct device *dev = kobj_to_dev(kobj);

  	int retval = 0;

  	/* add device node properties if present */

  	if (MAJOR(dev->devt)) {

  		const char *tmp;
  		const char *name;

  		umode_t mode = 0;

  		kuid_t uid = GLOBAL_ROOT_UID;
  		kgid_t gid = GLOBAL_ROOT_GID;

  		add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
  		add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));

  		name = device_get_devnode(dev, &mode, &uid, &gid, &tmp);

  		if (name) {
  			add_uevent_var(env, "DEVNAME=%s", name);

  			if (mode)
  				add_uevent_var(env, "DEVMODE=%#o", mode & 0777);

  			if (!uid_eq(uid, GLOBAL_ROOT_UID))
  				add_uevent_var(env, "DEVUID=%u", from_kuid(&init_user_ns, uid));
  			if (!gid_eq(gid, GLOBAL_ROOT_GID))
  				add_uevent_var(env, "DEVGID=%u", from_kgid(&init_user_ns, gid));

  			kfree(tmp);

  		}

  	}

  	if (dev->type && dev->type->name)

  		add_uevent_var(env, "DEVTYPE=%s", dev->type->name);

  	if (dev->driver)

  		add_uevent_var(env, "DRIVER=%s", dev->driver->name);

  	/* Add common DT information about the device */
  	of_device_uevent(dev, env);

  	/* have the bus specific function add its stuff */

  	if (dev->bus && dev->bus->uevent) {

  		retval = dev->bus->uevent(dev, env);

  		if (retval)

  			pr_debug("device: '%s': %s: bus uevent() returned %d
  ",

  				 dev_name(dev), __func__, retval);

  	}

  	/* have the class specific function add its stuff */

  	if (dev->class && dev->class->dev_uevent) {

  		retval = dev->class->dev_uevent(dev, env);

  		if (retval)

  			pr_debug("device: '%s': %s: class uevent() "

  				 "returned %d
  ", dev_name(dev),

  				 __func__, retval);

  	}

  	/* have the device type specific function add its stuff */

  	if (dev->type && dev->type->uevent) {

  		retval = dev->type->uevent(dev, env);

  		if (retval)

  			pr_debug("device: '%s': %s: dev_type uevent() "

  				 "returned %d
  ", dev_name(dev),

  				 __func__, retval);

  	}

  	return retval;
  }

  static const struct kset_uevent_ops device_uevent_ops = {

  	.filter =	dev_uevent_filter,
  	.name =		dev_uevent_name,
  	.uevent =	dev_uevent,

  };

  static ssize_t uevent_show(struct device *dev, struct device_attribute *attr,

  			   char *buf)
  {
  	struct kobject *top_kobj;
  	struct kset *kset;

  	struct kobj_uevent_env *env = NULL;

  	int i;
  	size_t count = 0;
  	int retval;
  
  	/* search the kset, the device belongs to */
  	top_kobj = &dev->kobj;

  	while (!top_kobj->kset && top_kobj->parent)
  		top_kobj = top_kobj->parent;

  	if (!top_kobj->kset)
  		goto out;

  	kset = top_kobj->kset;
  	if (!kset->uevent_ops || !kset->uevent_ops->uevent)
  		goto out;
  
  	/* respect filter */
  	if (kset->uevent_ops && kset->uevent_ops->filter)
  		if (!kset->uevent_ops->filter(kset, &dev->kobj))
  			goto out;

  	env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
  	if (!env)

  		return -ENOMEM;

  	/* let the kset specific function add its keys */

  	retval = kset->uevent_ops->uevent(kset, &dev->kobj, env);

  	if (retval)
  		goto out;
  
  	/* copy keys to file */

  	for (i = 0; i < env->envp_idx; i++)
  		count += sprintf(&buf[count], "%s
  ", env->envp[i]);

  out:

  	kfree(env);

  	return count;
  }

  static ssize_t uevent_store(struct device *dev, struct device_attribute *attr,

  			    const char *buf, size_t count)
  {

  	enum kobject_action action;

  	if (kobject_action_type(buf, count, &action) == 0)

  		kobject_uevent(&dev->kobj, action);

  	else
  		dev_err(dev, "uevent: unknown action-string
  ");

  	return count;
  }

  static DEVICE_ATTR_RW(uevent);

  static ssize_t online_show(struct device *dev, struct device_attribute *attr,

  			   char *buf)
  {
  	bool val;

  	device_lock(dev);

  	val = !dev->offline;

  	device_unlock(dev);

  	return sprintf(buf, "%u
  ", val);
  }

  static ssize_t online_store(struct device *dev, struct device_attribute *attr,

  			    const char *buf, size_t count)
  {
  	bool val;
  	int ret;
  
  	ret = strtobool(buf, &val);
  	if (ret < 0)
  		return ret;

  	ret = lock_device_hotplug_sysfs();
  	if (ret)
  		return ret;

  	ret = val ? device_online(dev) : device_offline(dev);
  	unlock_device_hotplug();
  	return ret < 0 ? ret : count;
  }

  static DEVICE_ATTR_RW(online);

  int device_add_groups(struct device *dev, const struct attribute_group **groups)

  {

  	return sysfs_create_groups(&dev->kobj, groups);

  }

  void device_remove_groups(struct device *dev,
  			  const struct attribute_group **groups)

  {

  	sysfs_remove_groups(&dev->kobj, groups);

  }

  static int device_add_attrs(struct device *dev)
  {
  	struct class *class = dev->class;

  	const struct device_type *type = dev->type;

  	int error;

  	if (class) {

  		error = device_add_groups(dev, class->dev_groups);

  		if (error)

  			return error;

  	}

  	if (type) {
  		error = device_add_groups(dev, type->groups);

  		if (error)

  			goto err_remove_class_groups;

  	}

  	error = device_add_groups(dev, dev->groups);
  	if (error)
  		goto err_remove_type_groups;

  	if (device_supports_offline(dev) && !dev->offline_disabled) {

  		error = device_create_file(dev, &dev_attr_online);

  		if (error)

  			goto err_remove_dev_groups;

  	}

  	return 0;

   err_remove_dev_groups:
  	device_remove_groups(dev, dev->groups);

   err_remove_type_groups:
  	if (type)
  		device_remove_groups(dev, type->groups);

   err_remove_class_groups:
  	if (class)
  		device_remove_groups(dev, class->dev_groups);

  	return error;
  }
  
  static void device_remove_attrs(struct device *dev)
  {
  	struct class *class = dev->class;

  	const struct device_type *type = dev->type;

  	device_remove_file(dev, &dev_attr_online);

  	device_remove_groups(dev, dev->groups);

  	if (type)
  		device_remove_groups(dev, type->groups);

  	if (class)

  		device_remove_groups(dev, class->dev_groups);

  }

  static ssize_t dev_show(struct device *dev, struct device_attribute *attr,

  			char *buf)
  {
  	return print_dev_t(buf, dev->devt);
  }

  static DEVICE_ATTR_RO(dev);

  /* /sys/devices/ */

  struct kset *devices_kset;

  /**

   * devices_kset_move_before - Move device in the devices_kset's list.
   * @deva: Device to move.
   * @devb: Device @deva should come before.
   */
  static void devices_kset_move_before(struct device *deva, struct device *devb)
  {
  	if (!devices_kset)
  		return;
  	pr_debug("devices_kset: Moving %s before %s
  ",
  		 dev_name(deva), dev_name(devb));
  	spin_lock(&devices_kset->list_lock);
  	list_move_tail(&deva->kobj.entry, &devb->kobj.entry);
  	spin_unlock(&devices_kset->list_lock);
  }
  
  /**
   * devices_kset_move_after - Move device in the devices_kset's list.
   * @deva: Device to move
   * @devb: Device @deva should come after.
   */
  static void devices_kset_move_after(struct device *deva, struct device *devb)
  {
  	if (!devices_kset)
  		return;
  	pr_debug("devices_kset: Moving %s after %s
  ",
  		 dev_name(deva), dev_name(devb));
  	spin_lock(&devices_kset->list_lock);
  	list_move(&deva->kobj.entry, &devb->kobj.entry);
  	spin_unlock(&devices_kset->list_lock);
  }
  
  /**
   * devices_kset_move_last - move the device to the end of devices_kset's list.
   * @dev: device to move
   */
  void devices_kset_move_last(struct device *dev)
  {
  	if (!devices_kset)
  		return;
  	pr_debug("devices_kset: Moving %s to end of list
  ", dev_name(dev));
  	spin_lock(&devices_kset->list_lock);
  	list_move_tail(&dev->kobj.entry, &devices_kset->list);
  	spin_unlock(&devices_kset->list_lock);
  }
  
  /**

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

   */

  int device_create_file(struct device *dev,
  		       const struct device_attribute *attr)

  {
  	int error = 0;

  
  	if (dev) {
  		WARN(((attr->attr.mode & S_IWUGO) && !attr->store),

  			"Attribute %s: write permission without 'store'
  ",
  			attr->attr.name);

  		WARN(((attr->attr.mode & S_IRUGO) && !attr->show),

  			"Attribute %s: read permission without 'show'
  ",
  			attr->attr.name);

  		error = sysfs_create_file(&dev->kobj, &attr->attr);

  	}

  	return error;
  }

  EXPORT_SYMBOL_GPL(device_create_file);

  
  /**

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

   */

  void device_remove_file(struct device *dev,
  			const struct device_attribute *attr)

  {

  	if (dev)

  		sysfs_remove_file(&dev->kobj, &attr->attr);

  }

  EXPORT_SYMBOL_GPL(device_remove_file);

  /**

   * device_remove_file_self - remove sysfs attribute file from its own method.
   * @dev: device.
   * @attr: device attribute descriptor.
   *
   * See kernfs_remove_self() for details.
   */
  bool device_remove_file_self(struct device *dev,
  			     const struct device_attribute *attr)
  {
  	if (dev)
  		return sysfs_remove_file_self(&dev->kobj, &attr->attr);
  	else
  		return false;
  }
  EXPORT_SYMBOL_GPL(device_remove_file_self);
  
  /**

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

  int device_create_bin_file(struct device *dev,
  			   const struct bin_attribute *attr)

  {
  	int error = -EINVAL;
  	if (dev)
  		error = sysfs_create_bin_file(&dev->kobj, attr);
  	return error;
  }
  EXPORT_SYMBOL_GPL(device_create_bin_file);
  
  /**
   * device_remove_bin_file - remove sysfs binary attribute file
   * @dev: device.
   * @attr: device binary attribute descriptor.
   */

  void device_remove_bin_file(struct device *dev,
  			    const struct bin_attribute *attr)

  {
  	if (dev)
  		sysfs_remove_bin_file(&dev->kobj, attr);
  }
  EXPORT_SYMBOL_GPL(device_remove_bin_file);

  static void klist_children_get(struct klist_node *n)
  {

  	struct device_private *p = to_device_private_parent(n);
  	struct device *dev = p->device;

  
  	get_device(dev);
  }
  
  static void klist_children_put(struct klist_node *n)
  {

  	struct device_private *p = to_device_private_parent(n);
  	struct device *dev = p->device;

  
  	put_device(dev);
  }

  /**

   * device_initialize - init device structure.
   * @dev: device.

   *

   * This prepares the device for use by other layers by initializing
   * its fields.

   * It is the first half of device_register(), if called by

   * that function, though it can also be called separately, so one
   * may use @dev's fields. In particular, get_device()/put_device()
   * may be used for reference counting of @dev after calling this
   * function.
   *

   * All fields in @dev must be initialized by the caller to 0, except
   * for those explicitly set to some other value.  The simplest
   * approach is to use kzalloc() to allocate the structure containing
   * @dev.
   *

   * NOTE: Use put_device() to give up your reference instead of freeing
   * @dev directly once you have called this function.

   */

  void device_initialize(struct device *dev)
  {

  	dev->kobj.kset = devices_kset;

  	kobject_init(&dev->kobj, &device_ktype);

  	INIT_LIST_HEAD(&dev->dma_pools);

  	mutex_init(&dev->mutex);

  	lockdep_set_novalidate_class(&dev->mutex);

  	spin_lock_init(&dev->devres_lock);
  	INIT_LIST_HEAD(&dev->devres_head);

  	device_pm_init(dev);

  	set_dev_node(dev, -1);

  #ifdef CONFIG_GENERIC_MSI_IRQ
  	INIT_LIST_HEAD(&dev->msi_list);
  #endif

  }

  EXPORT_SYMBOL_GPL(device_initialize);

  struct kobject *virtual_device_parent(struct device *dev)

  {

  	static struct kobject *virtual_dir = NULL;

  	if (!virtual_dir)

  		virtual_dir = kobject_create_and_add("virtual",

  						     &devices_kset->kobj);

  	return virtual_dir;

  }

  struct class_dir {
  	struct kobject kobj;
  	struct class *class;
  };
  
  #define to_class_dir(obj) container_of(obj, struct class_dir, kobj)
  
  static void class_dir_release(struct kobject *kobj)
  {
  	struct class_dir *dir = to_class_dir(kobj);
  	kfree(dir);
  }
  
  static const
  struct kobj_ns_type_operations *class_dir_child_ns_type(struct kobject *kobj)

  {

  	struct class_dir *dir = to_class_dir(kobj);
  	return dir->class->ns_type;
  }
  
  static struct kobj_type class_dir_ktype = {
  	.release	= class_dir_release,
  	.sysfs_ops	= &kobj_sysfs_ops,
  	.child_ns_type	= class_dir_child_ns_type
  };
  
  static struct kobject *
  class_dir_create_and_add(struct class *class, struct kobject *parent_kobj)
  {
  	struct class_dir *dir;

  	int retval;

  	dir = kzalloc(sizeof(*dir), GFP_KERNEL);
  	if (!dir)
  		return NULL;
  
  	dir->class = class;
  	kobject_init(&dir->kobj, &class_dir_ktype);

  	dir->kobj.kset = &class->p->glue_dirs;

  
  	retval = kobject_add(&dir->kobj, parent_kobj, "%s", class->name);
  	if (retval < 0) {
  		kobject_put(&dir->kobj);
  		return NULL;
  	}
  	return &dir->kobj;
  }

  static DEFINE_MUTEX(gdp_mutex);

  
  static struct kobject *get_device_parent(struct device *dev,
  					 struct device *parent)
  {

  	if (dev->class) {
  		struct kobject *kobj = NULL;
  		struct kobject *parent_kobj;
  		struct kobject *k;

  #ifdef CONFIG_BLOCK

  		/* block disks show up in /sys/block */

  		if (sysfs_deprecated && dev->class == &block_class) {

  			if (parent && parent->class == &block_class)
  				return &parent->kobj;

  			return &block_class.p->subsys.kobj;

  		}

  #endif

  		/*
  		 * If we have no parent, we live in "virtual".

  		 * Class-devices with a non class-device as parent, live
  		 * in a "glue" directory to prevent namespace collisions.

  		 */
  		if (parent == NULL)
  			parent_kobj = virtual_device_parent(dev);

  		else if (parent->class && !dev->class->ns_type)

  			return &parent->kobj;
  		else
  			parent_kobj = &parent->kobj;

  		mutex_lock(&gdp_mutex);

  		/* find our class-directory at the parent and reference it */

  		spin_lock(&dev->class->p->glue_dirs.list_lock);
  		list_for_each_entry(k, &dev->class->p->glue_dirs.list, entry)

  			if (k->parent == parent_kobj) {
  				kobj = kobject_get(k);
  				break;
  			}

  		spin_unlock(&dev->class->p->glue_dirs.list_lock);

  		if (kobj) {
  			mutex_unlock(&gdp_mutex);

  			return kobj;

  		}

  
  		/* or create a new class-directory at the parent device */

  		k = class_dir_create_and_add(dev->class, parent_kobj);

  		/* do not emit an uevent for this simple "glue" directory */

  		mutex_unlock(&gdp_mutex);

  		return k;

  	}

  	/* subsystems can specify a default root directory for their devices */
  	if (!parent && dev->bus && dev->bus->dev_root)
  		return &dev->bus->dev_root->kobj;

  	if (parent)

  		return &parent->kobj;
  	return NULL;
  }

  static inline bool live_in_glue_dir(struct kobject *kobj,
  				    struct device *dev)
  {
  	if (!kobj || !dev->class ||
  	    kobj->kset != &dev->class->p->glue_dirs)
  		return false;
  	return true;
  }
  
  static inline struct kobject *get_glue_dir(struct device *dev)
  {
  	return dev->kobj.parent;
  }
  
  /*
   * make sure cleaning up dir as the last step, we need to make
   * sure .release handler of kobject is run with holding the
   * global lock
   */

  static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)

  {

  	/* see if we live in a "glue" directory */

  	if (!live_in_glue_dir(glue_dir, dev))

  		return;

  	mutex_lock(&gdp_mutex);

  	kobject_put(glue_dir);

  	mutex_unlock(&gdp_mutex);

  }

  static int device_add_class_symlinks(struct device *dev)
  {

  	struct device_node *of_node = dev_of_node(dev);

  	int error;

  	if (of_node) {
  		error = sysfs_create_link(&dev->kobj, &of_node->kobj,"of_node");
  		if (error)
  			dev_warn(dev, "Error %d creating of_node link
  ",error);
  		/* An error here doesn't warrant bringing down the device */
  	}

  	if (!dev->class)
  		return 0;

  	error = sysfs_create_link(&dev->kobj,

  				  &dev->class->p->subsys.kobj,

  				  "subsystem");
  	if (error)

  		goto out_devnode;

  	if (dev->parent && device_is_not_partition(dev)) {

  		error = sysfs_create_link(&dev->kobj, &dev->parent->kobj,

  					  "device");
  		if (error)

  			goto out_subsys;

  	}

  #ifdef CONFIG_BLOCK

  	/* /sys/block has directories and does not need symlinks */

  	if (sysfs_deprecated && dev->class == &block_class)

  		return 0;

  #endif

  	/* link in the class directory pointing to the device */

  	error = sysfs_create_link(&dev->class->p->subsys.kobj,

  				  &dev->kobj, dev_name(dev));

  	if (error)

  		goto out_device;

  	return 0;

  out_device:
  	sysfs_remove_link(&dev->kobj, "device");

  out_subsys:
  	sysfs_remove_link(&dev->kobj, "subsystem");

  out_devnode:
  	sysfs_remove_link(&dev->kobj, "of_node");

  	return error;
  }
  
  static void device_remove_class_symlinks(struct device *dev)
  {

  	if (dev_of_node(dev))
  		sysfs_remove_link(&dev->kobj, "of_node");

  	if (!dev->class)
  		return;

  	if (dev->parent && device_is_not_partition(dev))

  		sysfs_remove_link(&dev->kobj, "device");

  	sysfs_remove_link(&dev->kobj, "subsystem");

  #ifdef CONFIG_BLOCK

  	if (sysfs_deprecated && dev->class == &block_class)

  		return;

  #endif

  	sysfs_delete_link(&dev->class->p->subsys.kobj, &dev->kobj, dev_name(dev));

  }

  /**

   * dev_set_name - set a device name
   * @dev: device

   * @fmt: format string for the device's name

   */
  int dev_set_name(struct device *dev, const char *fmt, ...)
  {
  	va_list vargs;

  	int err;

  
  	va_start(vargs, fmt);

  	err = kobject_set_name_vargs(&dev->kobj, fmt, vargs);

  	va_end(vargs);

  	return err;

  }
  EXPORT_SYMBOL_GPL(dev_set_name);
  
  /**

   * device_to_dev_kobj - select a /sys/dev/ directory for the device
   * @dev: device
   *
   * By default we select char/ for new entries.  Setting class->dev_obj
   * to NULL prevents an entry from being created.  class->dev_kobj must
   * be set (or cleared) before any devices are registered to the class
   * otherwise device_create_sys_dev_entry() and

   * device_remove_sys_dev_entry() will disagree about the presence of
   * the link.

   */
  static struct kobject *device_to_dev_kobj(struct device *dev)
  {
  	struct kobject *kobj;
  
  	if (dev->class)
  		kobj = dev->class->dev_kobj;
  	else
  		kobj = sysfs_dev_char_kobj;
  
  	return kobj;
  }
  
  static int device_create_sys_dev_entry(struct device *dev)
  {
  	struct kobject *kobj = device_to_dev_kobj(dev);
  	int error = 0;
  	char devt_str[15];
  
  	if (kobj) {
  		format_dev_t(devt_str, dev->devt);
  		error = sysfs_create_link(kobj, &dev->kobj, devt_str);
  	}
  
  	return error;
  }
  
  static void device_remove_sys_dev_entry(struct device *dev)
  {
  	struct kobject *kobj = device_to_dev_kobj(dev);
  	char devt_str[15];
  
  	if (kobj) {
  		format_dev_t(devt_str, dev->devt);
  		sysfs_remove_link(kobj, devt_str);
  	}
  }

  int device_private_init(struct device *dev)
  {
  	dev->p = kzalloc(sizeof(*dev->p), GFP_KERNEL);
  	if (!dev->p)
  		return -ENOMEM;
  	dev->p->device = dev;
  	klist_init(&dev->p->klist_children, klist_children_get,
  		   klist_children_put);

  	INIT_LIST_HEAD(&dev->p->deferred_probe);

  	return 0;
  }

  /**

   * 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 @dev 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.

   *

   * Do not call this routine or device_register() more than once for
   * any device structure.  The driver model core is not designed to work
   * with devices that get unregistered and then spring back to life.
   * (Among other things, it's very hard to guarantee that all references
   * to the previous incarnation of @dev have been dropped.)  Allocate
   * and register a fresh new struct device instead.
   *

   * NOTE: _Never_ directly free @dev after calling this function, even
   * if it returned an error! Always use put_device() to give up your
   * reference instead.

   */
  int device_add(struct device *dev)
  {
  	struct device *parent = NULL;

  	struct kobject *kobj;

  	struct class_interface *class_intf;

  	int error = -EINVAL;

  	struct kobject *glue_dir = NULL;

  	dev = get_device(dev);

  	if (!dev)
  		goto done;

  	if (!dev->p) {

  		error = device_private_init(dev);
  		if (error)
  			goto done;

  	}

  	/*
  	 * for statically allocated devices, which should all be converted
  	 * some day, we need to initialize the name. We prevent reading back
  	 * the name, and force the use of dev_name()
  	 */
  	if (dev->init_name) {

  		dev_set_name(dev, "%s", dev->init_name);

  		dev->init_name = NULL;
  	}

  	/* subsystems can specify simple device enumeration */
  	if (!dev_name(dev) && dev->bus && dev->bus->dev_name)
  		dev_set_name(dev, "%s%u", dev->bus->dev_name, dev->id);

  	if (!dev_name(dev)) {
  		error = -EINVAL;

  		goto name_error;

  	}

  	pr_debug("device: '%s': %s
  ", dev_name(dev), __func__);

  	parent = get_device(dev->parent);

  	kobj = get_device_parent(dev, parent);
  	if (kobj)
  		dev->kobj.parent = kobj;

  	/* use parent numa_node */

  	if (parent && (dev_to_node(dev) == NUMA_NO_NODE))

  		set_dev_node(dev, dev_to_node(parent));

  	/* first, register with generic layer. */

  	/* we require the name to be set before, and pass NULL */
  	error = kobject_add(&dev->kobj, dev->kobj.parent, NULL);

  	if (error) {
  		glue_dir = get_glue_dir(dev);

  		goto Error;

  	}

  	/* notify platform of device entry */
  	if (platform_notify)
  		platform_notify(dev);

  	error = device_create_file(dev, &dev_attr_uevent);

  	if (error)
  		goto attrError;

  	error = device_add_class_symlinks(dev);
  	if (error)
  		goto SymlinkError;

  	error = device_add_attrs(dev);
  	if (error)

  		goto AttrsError;

  	error = bus_add_device(dev);
  	if (error)

  		goto BusError;

  	error = dpm_sysfs_add(dev);

  	if (error)

  		goto DPMError;
  	device_pm_add(dev);

  	if (MAJOR(dev->devt)) {
  		error = device_create_file(dev, &dev_attr_dev);
  		if (error)
  			goto DevAttrError;
  
  		error = device_create_sys_dev_entry(dev);
  		if (error)
  			goto SysEntryError;
  
  		devtmpfs_create_node(dev);
  	}

  	/* Notify clients of device addition.  This call must come

  	 * after dpm_sysfs_add() and before kobject_uevent().

  	 */
  	if (dev->bus)
  		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
  					     BUS_NOTIFY_ADD_DEVICE, dev);

  	kobject_uevent(&dev->kobj, KOBJ_ADD);

  	bus_probe_device(dev);

  	if (parent)

  		klist_add_tail(&dev->p->knode_parent,
  			       &parent->p->klist_children);

  	if (dev->class) {

  		mutex_lock(&dev->class->p->mutex);

  		/* tie the class to the device */

  		klist_add_tail(&dev->knode_class,

  			       &dev->class->p->klist_devices);

  
  		/* notify any interfaces that the device is here */

  		list_for_each_entry(class_intf,

  				    &dev->class->p->interfaces, node)

  			if (class_intf->add_dev)
  				class_intf->add_dev(dev, class_intf);

  		mutex_unlock(&dev->class->p->mutex);

  	}

  done:

  	put_device(dev);
  	return error;

   SysEntryError:
  	if (MAJOR(dev->devt))
  		device_remove_file(dev, &dev_attr_dev);
   DevAttrError:
  	device_pm_remove(dev);
  	dpm_sysfs_remove(dev);

   DPMError:

  	bus_remove_device(dev);
   BusError:

  	device_remove_attrs(dev);

   AttrsError:

  	device_remove_class_symlinks(dev);
   SymlinkError:

  	device_remove_file(dev, &dev_attr_uevent);

   attrError:

  	kobject_uevent(&dev->kobj, KOBJ_REMOVE);

  	glue_dir = get_glue_dir(dev);

  	kobject_del(&dev->kobj);
   Error:

  	cleanup_glue_dir(dev, glue_dir);

  	put_device(parent);

  name_error:
  	kfree(dev->p);
  	dev->p = NULL;

  	goto done;

  }

  EXPORT_SYMBOL_GPL(device_add);

  /**

   * 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.

   *

   * For more information, see the kerneldoc for device_initialize()
   * and device_add().
   *

   * NOTE: _Never_ directly free @dev after calling this function, even
   * if it returned an error! Always use put_device() to give up the
   * reference initialized in this function instead.

   */

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

  EXPORT_SYMBOL_GPL(device_register);

  /**

   * 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 ? kobj_to_dev(kobject_get(&dev->kobj)) : NULL;

  }

  EXPORT_SYMBOL_GPL(get_device);

  /**

   * put_device - decrement reference count.
   * @dev: device in question.

   */

  void put_device(struct device *dev)

  {

  	/* might_sleep(); */

  	if (dev)
  		kobject_put(&dev->kobj);
  }

  EXPORT_SYMBOL_GPL(put_device);

  /**

   * 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;

  	struct kobject *glue_dir = NULL;

  	struct class_interface *class_intf;

  	/* Notify clients of device removal.  This call must come
  	 * before dpm_sysfs_remove().
  	 */
  	if (dev->bus)
  		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
  					     BUS_NOTIFY_DEL_DEVICE, dev);

  	dpm_sysfs_remove(dev);

  	if (parent)

  		klist_del(&dev->p->knode_parent);

  	if (MAJOR(dev->devt)) {

  		devtmpfs_delete_node(dev);

  		device_remove_sys_dev_entry(dev);

  		device_remove_file(dev, &dev_attr_dev);

  	}

  	if (dev->class) {

  		device_remove_class_symlinks(dev);

  		mutex_lock(&dev->class->p->mutex);

  		/* notify any interfaces that the device is now gone */

  		list_for_each_entry(class_intf,

  				    &dev->class->p->interfaces, node)

  			if (class_intf->remove_dev)
  				class_intf->remove_dev(dev, class_intf);
  		/* remove the device from the class list */

  		klist_del(&dev->knode_class);

  		mutex_unlock(&dev->class->p->mutex);

  	}

  	device_remove_file(dev, &dev_attr_uevent);

  	device_remove_attrs(dev);

  	bus_remove_device(dev);

  	device_pm_remove(dev);

  	driver_deferred_probe_del(dev);

  	device_remove_properties(dev);

  
  	/* Notify the platform of the removal, in case they
  	 * need to do anything...
  	 */
  	if (platform_notify_remove)
  		platform_notify_remove(dev);

  	if (dev->bus)
  		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
  					     BUS_NOTIFY_REMOVED_DEVICE, dev);

  	kobject_uevent(&dev->kobj, KOBJ_REMOVE);

  	glue_dir = get_glue_dir(dev);

  	kobject_del(&dev->kobj);

  	cleanup_glue_dir(dev, glue_dir);

  	put_device(parent);

  }

  EXPORT_SYMBOL_GPL(device_del);

  
  /**

   * 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("device: '%s': %s
  ", dev_name(dev), __func__);

  	device_del(dev);
  	put_device(dev);
  }

  EXPORT_SYMBOL_GPL(device_unregister);

  static struct device *prev_device(struct klist_iter *i)
  {
  	struct klist_node *n = klist_prev(i);
  	struct device *dev = NULL;
  	struct device_private *p;
  
  	if (n) {
  		p = to_device_private_parent(n);
  		dev = p->device;
  	}
  	return dev;
  }

  static struct device *next_device(struct klist_iter *i)

  {

  	struct klist_node *n = klist_next(i);

  	struct device *dev = NULL;
  	struct device_private *p;
  
  	if (n) {
  		p = to_device_private_parent(n);
  		dev = p->device;
  	}
  	return dev;

  }

  /**

   * device_get_devnode - path of device node file

   * @dev: device

   * @mode: returned file access mode

   * @uid: returned file owner
   * @gid: returned file group

   * @tmp: possibly allocated string
   *
   * Return the relative path of a possible device node.
   * Non-default names may need to allocate a memory to compose
   * a name. This memory is returned in tmp and needs to be
   * freed by the caller.
   */

  const char *device_get_devnode(struct device *dev,

  			       umode_t *mode, kuid_t *uid, kgid_t *gid,

  			       const char **tmp)

  {
  	char *s;
  
  	*tmp = NULL;
  
  	/* the device type may provide a specific name */

  	if (dev->type && dev->type->devnode)

  		*tmp = dev->type->devnode(dev, mode, uid, gid);

  	if (*tmp)
  		return *tmp;
  
  	/* the class may provide a specific name */

  	if (dev->class && dev->class->devnode)
  		*tmp = dev->class->devnode(dev, mode);

  	if (*tmp)
  		return *tmp;
  
  	/* return name without allocation, tmp == NULL */
  	if (strchr(dev_name(dev), '!') == NULL)
  		return dev_name(dev);
  
  	/* replace '!' in the name with '/' */

  	s = kstrdup(dev_name(dev), GFP_KERNEL);
  	if (!s)

  		return NULL;

  	strreplace(s, '!', '/');
  	return *tmp = s;

  }
  
  /**

   * device_for_each_child - device child iterator.
   * @parent: parent struct device.

   * @fn: function to be called for each device.

   * @data: data for the callback.

   *

   * Iterate over @parent'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 *dev, void *data))

  {

  	struct klist_iter i;

  	struct device *child;

  	int error = 0;

  	if (!parent->p)
  		return 0;

  	klist_iter_init(&parent->p->klist_children, &i);

  	while ((child = next_device(&i)) && !error)
  		error = fn(child, data);
  	klist_iter_exit(&i);

  	return error;
  }

  EXPORT_SYMBOL_GPL(device_for_each_child);

  /**

   * device_for_each_child_reverse - device child iterator in reversed order.
   * @parent: parent struct device.
   * @fn: function to be called for each device.
   * @data: data for the callback.
   *
   * Iterate over @parent'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_reverse(struct device *parent, void *data,
  				  int (*fn)(struct device *dev, void *data))
  {
  	struct klist_iter i;
  	struct device *child;
  	int error = 0;
  
  	if (!parent->p)
  		return 0;
  
  	klist_iter_init(&parent->p->klist_children, &i);
  	while ((child = prev_device(&i)) && !error)
  		error = fn(child, data);
  	klist_iter_exit(&i);
  	return error;
  }
  EXPORT_SYMBOL_GPL(device_for_each_child_reverse);
  
  /**

   * device_find_child - device iterator for locating a particular device.
   * @parent: parent struct device

   * @match: Callback function to check device

   * @data: Data to pass to match function

   *
   * This is similar to the device_for_each_child() function above, but it
   * returns a reference to a device that is 'found' for later use, as
   * determined by the @match callback.
   *
   * The callback should return 0 if the device doesn't match and non-zero
   * if it does.  If the callback returns non-zero and a reference to the
   * current device can be obtained, this function will return to the caller
   * and not iterate over any more devices.

   *
   * NOTE: you will need to drop the reference with put_device() after use.