/*
   * kobject.c - library routines for handling generic kernel objects
   *
   * Copyright (c) 2002-2003 Patrick Mochel <mochel@osdl.org>
   *
   * This file is released under the GPLv2.
   *
   *
   * Please see the file Documentation/kobject.txt for critical information
   * about using the kobject interface.
   */
  
  #include <linux/kobject.h>
  #include <linux/string.h>
  #include <linux/module.h>
  #include <linux/stat.h>

  #include <linux/slab.h>

  
  /**
   *	populate_dir - populate directory with attributes.
   *	@kobj:	object we're working on.
   *
   *	Most subsystems have a set of default attributes that 
   *	are associated with an object that registers with them.
   *	This is a helper called during object registration that 
   *	loops through the default attributes of the subsystem 
   *	and creates attributes files for them in sysfs.
   *
   */
  
  static int populate_dir(struct kobject * kobj)
  {
  	struct kobj_type * t = get_ktype(kobj);
  	struct attribute * attr;
  	int error = 0;
  	int i;
  	
  	if (t && t->default_attrs) {
  		for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) {
  			if ((error = sysfs_create_file(kobj,attr)))
  				break;
  		}
  	}
  	return error;
  }
  
  static int create_dir(struct kobject * kobj)
  {
  	int error = 0;
  	if (kobject_name(kobj)) {
  		error = sysfs_create_dir(kobj);
  		if (!error) {
  			if ((error = populate_dir(kobj)))
  				sysfs_remove_dir(kobj);
  		}
  	}
  	return error;
  }
  
  static inline struct kobject * to_kobj(struct list_head * entry)
  {
  	return container_of(entry,struct kobject,entry);
  }
  
  static int get_kobj_path_length(struct kobject *kobj)
  {
  	int length = 1;
  	struct kobject * parent = kobj;
  
  	/* walk up the ancestors until we hit the one pointing to the 
  	 * root.
  	 * Add 1 to strlen for leading '/' of each level.
  	 */
  	do {

  		if (kobject_name(parent) == NULL)
  			return 0;

  		length += strlen(kobject_name(parent)) + 1;
  		parent = parent->parent;
  	} while (parent);
  	return length;
  }
  
  static void fill_kobj_path(struct kobject *kobj, char *path, int length)
  {
  	struct kobject * parent;
  
  	--length;
  	for (parent = kobj; parent; parent = parent->parent) {
  		int cur = strlen(kobject_name(parent));
  		/* back up enough to print this name with '/' */
  		length -= cur;
  		strncpy (path + length, kobject_name(parent), cur);
  		*(path + --length) = '/';
  	}
  
  	pr_debug("%s: path = '%s'
  ",__FUNCTION__,path);
  }
  
  /**
   * kobject_get_path - generate and return the path associated with a given kobj
   * and kset pair.  The result must be freed by the caller with kfree().
   *
   * @kobj:	kobject in question, with which to build the path
   * @gfp_mask:	the allocation type used to allocate the path
   */

  char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)

  {
  	char *path;
  	int len;
  
  	len = get_kobj_path_length(kobj);

  	if (len == 0)
  		return NULL;

  	path = kmalloc(len, gfp_mask);
  	if (!path)
  		return NULL;
  	memset(path, 0x00, len);
  	fill_kobj_path(kobj, path, len);
  
  	return path;
  }
  
  /**
   *	kobject_init - initialize object.
   *	@kobj:	object in question.
   */
  void kobject_init(struct kobject * kobj)
  {
  	kref_init(&kobj->kref);
  	INIT_LIST_HEAD(&kobj->entry);

  	init_waitqueue_head(&kobj->poll);

  	kobj->kset = kset_get(kobj->kset);
  }
  
  
  /**
   *	unlink - remove kobject from kset list.
   *	@kobj:	kobject.
   *
   *	Remove the kobject from the kset list and decrement
   *	its parent's refcount.
   *	This is separated out, so we can use it in both 
   *	kobject_del() and kobject_add() on error.
   */
  
  static void unlink(struct kobject * kobj)
  {
  	if (kobj->kset) {
  		spin_lock(&kobj->kset->list_lock);
  		list_del_init(&kobj->entry);
  		spin_unlock(&kobj->kset->list_lock);
  	}
  	kobject_put(kobj);
  }
  
  /**
   *	kobject_add - add an object to the hierarchy.
   *	@kobj:	object.
   */
  
  int kobject_add(struct kobject * kobj)
  {
  	int error = 0;
  	struct kobject * parent;
  
  	if (!(kobj = kobject_get(kobj)))
  		return -ENOENT;
  	if (!kobj->k_name)
  		kobj->k_name = kobj->name;

  	if (!kobj->k_name) {
  		pr_debug("kobject attempted to be registered with no name!
  ");
  		WARN_ON(1);
  		return -EINVAL;
  	}

  	parent = kobject_get(kobj->parent);
  
  	pr_debug("kobject %s: registering. parent: %s, set: %s
  ",
  		 kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>", 
  		 kobj->kset ? kobj->kset->kobj.name : "<NULL>" );
  
  	if (kobj->kset) {
  		spin_lock(&kobj->kset->list_lock);
  
  		if (!parent)
  			parent = kobject_get(&kobj->kset->kobj);
  
  		list_add_tail(&kobj->entry,&kobj->kset->list);
  		spin_unlock(&kobj->kset->list_lock);
  	}
  	kobj->parent = parent;
  
  	error = create_dir(kobj);
  	if (error) {
  		/* unlink does the kobject_put() for us */
  		unlink(kobj);
  		if (parent)
  			kobject_put(parent);

  
  		/* be noisy on error issues */
  		if (error == -EEXIST)

  			pr_debug("kobject_add failed for %s with -EEXIST, "

  			       "don't try to register things with the "
  			       "same name in the same directory.
  ",
  			       kobject_name(kobj));
  		else

  			pr_debug("kobject_add failed for %s (%d)
  ",

  			       kobject_name(kobj), error);

  		/* dump_stack(); */

  	}
  
  	return error;
  }
  
  
  /**
   *	kobject_register - initialize and add an object.
   *	@kobj:	object in question.
   */
  
  int kobject_register(struct kobject * kobj)
  {

  	int error = -EINVAL;

  	if (kobj) {
  		kobject_init(kobj);
  		error = kobject_add(kobj);

  		if (!error)

  			kobject_uevent(kobj, KOBJ_ADD);

  	}

  	return error;
  }
  
  
  /**
   *	kobject_set_name - Set the name of an object
   *	@kobj:	object.

   *	@fmt:	format string used to build the name

   *
   *	If strlen(name) >= KOBJ_NAME_LEN, then use a dynamically allocated
   *	string that @kobj->k_name points to. Otherwise, use the static 
   *	@kobj->name array.
   */

  int kobject_set_name(struct kobject * kobj, const char * fmt, ...)
  {
  	int error = 0;
  	int limit = KOBJ_NAME_LEN;
  	int need;
  	va_list args;
  	char * name;
  
  	/* 
  	 * First, try the static array 
  	 */
  	va_start(args,fmt);
  	need = vsnprintf(kobj->name,limit,fmt,args);
  	va_end(args);
  	if (need < limit) 
  		name = kobj->name;
  	else {
  		/* 
  		 * Need more space? Allocate it and try again 
  		 */
  		limit = need + 1;
  		name = kmalloc(limit,GFP_KERNEL);
  		if (!name) {
  			error = -ENOMEM;
  			goto Done;
  		}
  		va_start(args,fmt);
  		need = vsnprintf(name,limit,fmt,args);
  		va_end(args);
  
  		/* Still? Give up. */
  		if (need >= limit) {
  			kfree(name);
  			error = -EFAULT;
  			goto Done;
  		}
  	}
  
  	/* Free the old name, if necessary. */
  	if (kobj->k_name && kobj->k_name != kobj->name)
  		kfree(kobj->k_name);
  
  	/* Now, set the new name */
  	kobj->k_name = name;
   Done:
  	return error;
  }
  
  EXPORT_SYMBOL(kobject_set_name);
  
  
  /**
   *	kobject_rename - change the name of an object
   *	@kobj:	object in question.
   *	@new_name: object's new name
   */

  int kobject_rename(struct kobject * kobj, const char *new_name)

  {
  	int error = 0;
  
  	kobj = kobject_get(kobj);
  	if (!kobj)
  		return -EINVAL;
  	error = sysfs_rename_dir(kobj, new_name);
  	kobject_put(kobj);
  
  	return error;
  }
  
  /**
   *	kobject_del - unlink kobject from hierarchy.
   * 	@kobj:	object.
   */
  
  void kobject_del(struct kobject * kobj)
  {

  	sysfs_remove_dir(kobj);
  	unlink(kobj);
  }
  
  /**
   *	kobject_unregister - remove object from hierarchy and decrement refcount.
   *	@kobj:	object going away.
   */
  
  void kobject_unregister(struct kobject * kobj)
  {
  	pr_debug("kobject %s: unregistering
  ",kobject_name(kobj));

  	kobject_uevent(kobj, KOBJ_REMOVE);

  	kobject_del(kobj);
  	kobject_put(kobj);
  }
  
  /**
   *	kobject_get - increment refcount for object.
   *	@kobj:	object.
   */
  
  struct kobject * kobject_get(struct kobject * kobj)
  {
  	if (kobj)
  		kref_get(&kobj->kref);
  	return kobj;
  }
  
  /**
   *	kobject_cleanup - free kobject resources. 
   *	@kobj:	object.
   */
  
  void kobject_cleanup(struct kobject * kobj)
  {
  	struct kobj_type * t = get_ktype(kobj);
  	struct kset * s = kobj->kset;
  	struct kobject * parent = kobj->parent;
  
  	pr_debug("kobject %s: cleaning up
  ",kobject_name(kobj));
  	if (kobj->k_name != kobj->name)
  		kfree(kobj->k_name);
  	kobj->k_name = NULL;
  	if (t && t->release)
  		t->release(kobj);
  	if (s)
  		kset_put(s);
  	if (parent) 
  		kobject_put(parent);
  }
  
  static void kobject_release(struct kref *kref)
  {
  	kobject_cleanup(container_of(kref, struct kobject, kref));
  }
  
  /**
   *	kobject_put - decrement refcount for object.
   *	@kobj:	object.
   *
   *	Decrement the refcount, and if 0, call kobject_cleanup().
   */
  void kobject_put(struct kobject * kobj)
  {
  	if (kobj)
  		kref_put(&kobj->kref, kobject_release);
  }

  static void dir_release(struct kobject *kobj)
  {
  	kfree(kobj);
  }
  
  static struct kobj_type dir_ktype = {
  	.release	= dir_release,
  	.sysfs_ops	= NULL,
  	.default_attrs	= NULL,
  };
  
  /**
   *	kobject_add_dir - add sub directory of object.
   *	@parent:	object in which a directory is created.
   *	@name:	directory name.
   *
   *	Add a plain directory object as child of given object.
   */
  struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
  {
  	struct kobject *k;
  
  	if (!parent)
  		return NULL;
  
  	k = kzalloc(sizeof(*k), GFP_KERNEL);
  	if (!k)
  		return NULL;
  
  	k->parent = parent;
  	k->ktype = &dir_ktype;
  	kobject_set_name(k, name);
  	kobject_register(k);
  
  	return k;
  }

  /**
   *	kset_init - initialize a kset for use
   *	@k:	kset 
   */
  
  void kset_init(struct kset * k)
  {
  	kobject_init(&k->kobj);
  	INIT_LIST_HEAD(&k->list);
  	spin_lock_init(&k->list_lock);
  }
  
  
  /**
   *	kset_add - add a kset object to the hierarchy.
   *	@k:	kset.
   *
   *	Simply, this adds the kset's embedded kobject to the 
   *	hierarchy. 
   *	We also try to make sure that the kset's embedded kobject
   *	has a parent before it is added. We only care if the embedded
   *	kobject is not part of a kset itself, since kobject_add()
   *	assigns a parent in that case. 
   *	If that is the case, and the kset has a controlling subsystem,
   *	then we set the kset's parent to be said subsystem. 
   */
  
  int kset_add(struct kset * k)
  {
  	if (!k->kobj.parent && !k->kobj.kset && k->subsys)
  		k->kobj.parent = &k->subsys->kset.kobj;
  
  	return kobject_add(&k->kobj);
  }
  
  
  /**
   *	kset_register - initialize and add a kset.
   *	@k:	kset.
   */
  
  int kset_register(struct kset * k)
  {
  	kset_init(k);
  	return kset_add(k);
  }
  
  
  /**
   *	kset_unregister - remove a kset.
   *	@k:	kset.
   */
  
  void kset_unregister(struct kset * k)
  {
  	kobject_unregister(&k->kobj);
  }
  
  
  /**
   *	kset_find_obj - search for object in kset.
   *	@kset:	kset we're looking in.
   *	@name:	object's name.
   *
   *	Lock kset via @kset->subsys, and iterate over @kset->list,
   *	looking for a matching kobject. If matching object is found
   *	take a reference and return the object.
   */
  
  struct kobject * kset_find_obj(struct kset * kset, const char * name)
  {
  	struct list_head * entry;
  	struct kobject * ret = NULL;
  
  	spin_lock(&kset->list_lock);
  	list_for_each(entry,&kset->list) {
  		struct kobject * k = to_kobj(entry);
  		if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
  			ret = kobject_get(k);
  			break;
  		}
  	}
  	spin_unlock(&kset->list_lock);
  	return ret;
  }
  
  
  void subsystem_init(struct subsystem * s)
  {
  	init_rwsem(&s->rwsem);
  	kset_init(&s->kset);
  }
  
  /**
   *	subsystem_register - register a subsystem.
   *	@s:	the subsystem we're registering.
   *
   *	Once we register the subsystem, we want to make sure that 
   *	the kset points back to this subsystem for correct usage of 
   *	the rwsem. 
   */
  
  int subsystem_register(struct subsystem * s)
  {
  	int error;
  
  	subsystem_init(s);
  	pr_debug("subsystem %s: registering
  ",s->kset.kobj.name);
  
  	if (!(error = kset_add(&s->kset))) {
  		if (!s->kset.subsys)
  			s->kset.subsys = s;
  	}
  	return error;
  }
  
  void subsystem_unregister(struct subsystem * s)
  {
  	pr_debug("subsystem %s: unregistering
  ",s->kset.kobj.name);
  	kset_unregister(&s->kset);
  }
  
  
  /**
   *	subsystem_create_file - export sysfs attribute file.
   *	@s:	subsystem.
   *	@a:	subsystem attribute descriptor.
   */
  
  int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
  {
  	int error = 0;
  	if (subsys_get(s)) {
  		error = sysfs_create_file(&s->kset.kobj,&a->attr);
  		subsys_put(s);
  	}
  	return error;
  }
  
  
  /**
   *	subsystem_remove_file - remove sysfs attribute file.
   *	@s:	subsystem.
   *	@a:	attribute desciptor.
   */

  #if 0

  void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
  {
  	if (subsys_get(s)) {
  		sysfs_remove_file(&s->kset.kobj,&a->attr);
  		subsys_put(s);
  	}
  }

  #endif  /*  0  */

  
  EXPORT_SYMBOL(kobject_init);
  EXPORT_SYMBOL(kobject_register);
  EXPORT_SYMBOL(kobject_unregister);
  EXPORT_SYMBOL(kobject_get);
  EXPORT_SYMBOL(kobject_put);
  EXPORT_SYMBOL(kobject_add);
  EXPORT_SYMBOL(kobject_del);
  
  EXPORT_SYMBOL(kset_register);
  EXPORT_SYMBOL(kset_unregister);

  EXPORT_SYMBOL(subsystem_register);
  EXPORT_SYMBOL(subsystem_unregister);
  EXPORT_SYMBOL(subsys_create_file);