/*
   * class.c - basic device class management
   *
   * Copyright (c) 2002-3 Patrick Mochel
   * Copyright (c) 2002-3 Open Source Development Labs
   * Copyright (c) 2003-2004 Greg Kroah-Hartman
   * Copyright (c) 2003-2004 IBM Corp.
   *
   * This file is released under the GPLv2
   *
   */

  #include <linux/device.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/string.h>
  #include <linux/kdev_t.h>

  #include <linux/err.h>

  #include <linux/slab.h>

  #include <linux/genhd.h>

  #include <linux/mutex.h>

  #include "base.h"
  
  #define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)

  static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
  			       char *buf)

  {

  	struct class_attribute *class_attr = to_class_attr(attr);

  	struct subsys_private *cp = to_subsys_private(kobj);

  	ssize_t ret = -EIO;

  
  	if (class_attr->show)

  		ret = class_attr->show(cp->class, class_attr, buf);

  	return ret;
  }

  static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
  				const char *buf, size_t count)

  {

  	struct class_attribute *class_attr = to_class_attr(attr);

  	struct subsys_private *cp = to_subsys_private(kobj);

  	ssize_t ret = -EIO;

  
  	if (class_attr->store)

  		ret = class_attr->store(cp->class, class_attr, buf, count);

  	return ret;
  }

  static const void *class_attr_namespace(struct kobject *kobj,
  					const struct attribute *attr)
  {
  	struct class_attribute *class_attr = to_class_attr(attr);
  	struct subsys_private *cp = to_subsys_private(kobj);
  	const void *ns = NULL;
  
  	if (class_attr->namespace)
  		ns = class_attr->namespace(cp->class, class_attr);
  	return ns;
  }

  static void class_release(struct kobject *kobj)

  {

  	struct subsys_private *cp = to_subsys_private(kobj);

  	struct class *class = cp->class;

  
  	pr_debug("class '%s': release.
  ", class->name);
  
  	if (class->class_release)
  		class->class_release(class);
  	else
  		pr_debug("class '%s' does not have a release() function, "
  			 "be careful
  ", class->name);

  
  	kfree(cp);

  }

  static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj)
  {

  	struct subsys_private *cp = to_subsys_private(kobj);

  	struct class *class = cp->class;
  
  	return class->ns_type;
  }

  static const struct sysfs_ops class_sysfs_ops = {

  	.show	   = class_attr_show,
  	.store	   = class_attr_store,
  	.namespace = class_attr_namespace,

  };

  static struct kobj_type class_ktype = {

  	.sysfs_ops	= &class_sysfs_ops,
  	.release	= class_release,

  	.child_ns_type	= class_child_ns_type,

  };

  /* Hotplug events for classes go to the class subsys */

  static struct kset *class_kset;

  int class_create_file(struct class *cls, const struct class_attribute *attr)

  {
  	int error;

  	if (cls)

  		error = sysfs_create_file(&cls->p->subsys.kobj,

  					  &attr->attr);

  	else

  		error = -EINVAL;
  	return error;
  }

  void class_remove_file(struct class *cls, const struct class_attribute *attr)

  {
  	if (cls)

  		sysfs_remove_file(&cls->p->subsys.kobj, &attr->attr);

  }

  static struct class *class_get(struct class *cls)

  {
  	if (cls)

  		kset_get(&cls->p->subsys);

  	return cls;

  }

  static void class_put(struct class *cls)

  {

  	if (cls)

  		kset_put(&cls->p->subsys);

  }

  static int add_class_attrs(struct class *cls)

  {
  	int i;
  	int error = 0;
  
  	if (cls->class_attrs) {
  		for (i = 0; attr_name(cls->class_attrs[i]); i++) {

  			error = class_create_file(cls, &cls->class_attrs[i]);

  			if (error)

  				goto error;

  		}
  	}

  done:

  	return error;

  error:

  	while (--i >= 0)

  		class_remove_file(cls, &cls->class_attrs[i]);
  	goto done;

  }

  static void remove_class_attrs(struct class *cls)

  {
  	int i;
  
  	if (cls->class_attrs) {
  		for (i = 0; attr_name(cls->class_attrs[i]); i++)

  			class_remove_file(cls, &cls->class_attrs[i]);

  	}
  }

  static void klist_class_dev_get(struct klist_node *n)
  {
  	struct device *dev = container_of(n, struct device, knode_class);
  
  	get_device(dev);
  }
  
  static void klist_class_dev_put(struct klist_node *n)
  {
  	struct device *dev = container_of(n, struct device, knode_class);
  
  	put_device(dev);
  }

  int __class_register(struct class *cls, struct lock_class_key *key)

  {

  	struct subsys_private *cp;

  	int error;
  
  	pr_debug("device class '%s': registering
  ", cls->name);

  	cp = kzalloc(sizeof(*cp), GFP_KERNEL);
  	if (!cp)
  		return -ENOMEM;

  	klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);

  	INIT_LIST_HEAD(&cp->interfaces);

  	kset_init(&cp->glue_dirs);

  	__mutex_init(&cp->mutex, "subsys mutex", key);

  	error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);

  	if (error) {
  		kfree(cp);

  		return error;

  	}

  	/* set the default /sys/dev directory for devices of this class */
  	if (!cls->dev_kobj)
  		cls->dev_kobj = sysfs_dev_char_kobj;

  #if defined(CONFIG_BLOCK)

  	/* let the block class directory show up in the root of sysfs */

  	if (!sysfs_deprecated || cls != &block_class)

  		cp->subsys.kobj.kset = class_kset;

  #else

  	cp->subsys.kobj.kset = class_kset;

  #endif

  	cp->subsys.kobj.ktype = &class_ktype;

  	cp->class = cls;
  	cls->p = cp;

  	error = kset_register(&cp->subsys);

  	if (error) {
  		kfree(cp);
  		return error;

  	}

  	error = add_class_attrs(class_get(cls));
  	class_put(cls);

  	return error;
  }

  EXPORT_SYMBOL_GPL(__class_register);

  void class_unregister(struct class *cls)

  {
  	pr_debug("device class '%s': unregistering
  ", cls->name);
  	remove_class_attrs(cls);

  	kset_unregister(&cls->p->subsys);

  }

  static void class_create_release(struct class *cls)
  {

  	pr_debug("%s called for %s
  ", __func__, cls->name);

  	kfree(cls);
  }

  /**
   * class_create - create a struct class structure
   * @owner: pointer to the module that is to "own" this struct class
   * @name: pointer to a string for the name of this class.

   * @key: the lock_class_key for this class; used by mutex lock debugging

   *
   * This is used to create a struct class pointer that can then be used

   * in calls to device_create().

   *

   * Returns &struct class pointer on success, or ERR_PTR() on error.
   *

   * Note, the pointer created here is to be destroyed when finished by
   * making a call to class_destroy().
   */

  struct class *__class_create(struct module *owner, const char *name,
  			     struct lock_class_key *key)

  {
  	struct class *cls;
  	int retval;

  	cls = kzalloc(sizeof(*cls), GFP_KERNEL);

  	if (!cls) {
  		retval = -ENOMEM;
  		goto error;
  	}

  
  	cls->name = name;
  	cls->owner = owner;
  	cls->class_release = class_create_release;

  	retval = __class_register(cls, key);

  	if (retval)
  		goto error;
  
  	return cls;
  
  error:
  	kfree(cls);
  	return ERR_PTR(retval);
  }

  EXPORT_SYMBOL_GPL(__class_create);

  /**
   * class_destroy - destroys a struct class structure

   * @cls: pointer to the struct class that is to be destroyed

   *
   * Note, the pointer to be destroyed must have been created with a call
   * to class_create().
   */

  void class_destroy(struct class *cls)
  {
  	if ((cls == NULL) || (IS_ERR(cls)))
  		return;
  
  	class_unregister(cls);
  }

  /**

   * class_dev_iter_init - initialize class device iterator
   * @iter: class iterator to initialize
   * @class: the class we wanna iterate over
   * @start: the device to start iterating from, if any
   * @type: device_type of the devices to iterate over, NULL for all
   *
   * Initialize class iterator @iter such that it iterates over devices
   * of @class.  If @start is set, the list iteration will start there,
   * otherwise if it is NULL, the iteration starts at the beginning of
   * the list.
   */
  void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
  			 struct device *start, const struct device_type *type)
  {
  	struct klist_node *start_knode = NULL;
  
  	if (start)
  		start_knode = &start->knode_class;

  	klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);

  	iter->type = type;
  }
  EXPORT_SYMBOL_GPL(class_dev_iter_init);
  
  /**
   * class_dev_iter_next - iterate to the next device
   * @iter: class iterator to proceed
   *
   * Proceed @iter to the next device and return it.  Returns NULL if
   * iteration is complete.
   *
   * The returned device is referenced and won't be released till
   * iterator is proceed to the next device or exited.  The caller is
   * free to do whatever it wants to do with the device including
   * calling back into class code.
   */
  struct device *class_dev_iter_next(struct class_dev_iter *iter)
  {
  	struct klist_node *knode;
  	struct device *dev;
  
  	while (1) {
  		knode = klist_next(&iter->ki);
  		if (!knode)
  			return NULL;
  		dev = container_of(knode, struct device, knode_class);
  		if (!iter->type || iter->type == dev->type)
  			return dev;
  	}
  }
  EXPORT_SYMBOL_GPL(class_dev_iter_next);
  
  /**
   * class_dev_iter_exit - finish iteration
   * @iter: class iterator to finish
   *
   * Finish an iteration.  Always call this function after iteration is
   * complete whether the iteration ran till the end or not.
   */
  void class_dev_iter_exit(struct class_dev_iter *iter)
  {
  	klist_iter_exit(&iter->ki);
  }
  EXPORT_SYMBOL_GPL(class_dev_iter_exit);
  
  /**

   * class_for_each_device - device iterator
   * @class: the class we're iterating

   * @start: the device to start with in the list, if any.

   * @data: data for the callback
   * @fn: function to be called for each device
   *
   * Iterate over @class's list of devices, and call @fn for each,

   * passing it @data.  If @start is set, the list iteration will start
   * there, otherwise if it is NULL, the iteration starts at the
   * beginning of the list.

   *
   * We check the return of @fn each time. If it returns anything
   * other than 0, we break out and return that value.
   *

   * @fn is allowed to do anything including calling back into class
   * code.  There's no locking restriction.

   */

  int class_for_each_device(struct class *class, struct device *start,
  			  void *data, int (*fn)(struct device *, void *))

  {

  	struct class_dev_iter iter;

  	struct device *dev;
  	int error = 0;
  
  	if (!class)
  		return -EINVAL;

  	if (!class->p) {
  		WARN(1, "%s called for class '%s' before it was initialized",
  		     __func__, class->name);
  		return -EINVAL;
  	}

  	class_dev_iter_init(&iter, class, start, NULL);
  	while ((dev = class_dev_iter_next(&iter))) {

  		error = fn(dev, data);

  		if (error)
  			break;
  	}

  	class_dev_iter_exit(&iter);

  
  	return error;
  }
  EXPORT_SYMBOL_GPL(class_for_each_device);
  
  /**
   * class_find_device - device iterator for locating a particular device
   * @class: the class we're iterating

   * @start: Device to begin with

   * @data: data for the match function
   * @match: function to check device
   *
   * This is similar to the class_for_each_dev() 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, 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.
   *

   * @fn is allowed to do anything including calling back into class
   * code.  There's no locking restriction.

   */

  struct device *class_find_device(struct class *class, struct device *start,
  				 void *data,
  				 int (*match)(struct device *, void *))

  {

  	struct class_dev_iter iter;

  	struct device *dev;

  
  	if (!class)
  		return NULL;

  	if (!class->p) {
  		WARN(1, "%s called for class '%s' before it was initialized",
  		     __func__, class->name);
  		return NULL;
  	}

  	class_dev_iter_init(&iter, class, start, NULL);
  	while ((dev = class_dev_iter_next(&iter))) {

  		if (match(dev, data)) {

  			get_device(dev);

  			break;

  		}

  	}

  	class_dev_iter_exit(&iter);

  	return dev;

  }
  EXPORT_SYMBOL_GPL(class_find_device);

  int class_interface_register(struct class_interface *class_intf)
  {
  	struct class *parent;

  	struct class_dev_iter iter;

  	struct device *dev;

  
  	if (!class_intf || !class_intf->class)
  		return -ENODEV;
  
  	parent = class_get(class_intf->class);
  	if (!parent)
  		return -EINVAL;

  	mutex_lock(&parent->p->mutex);
  	list_add_tail(&class_intf->node, &parent->p->interfaces);

  	if (class_intf->add_dev) {

  		class_dev_iter_init(&iter, parent, NULL, NULL);
  		while ((dev = class_dev_iter_next(&iter)))

  			class_intf->add_dev(dev, class_intf);

  		class_dev_iter_exit(&iter);

  	}

  	mutex_unlock(&parent->p->mutex);

  
  	return 0;
  }
  
  void class_interface_unregister(struct class_interface *class_intf)
  {

  	struct class *parent = class_intf->class;

  	struct class_dev_iter iter;

  	struct device *dev;

  
  	if (!parent)
  		return;

  	mutex_lock(&parent->p->mutex);

  	list_del_init(&class_intf->node);

  	if (class_intf->remove_dev) {

  		class_dev_iter_init(&iter, parent, NULL, NULL);
  		while ((dev = class_dev_iter_next(&iter)))

  			class_intf->remove_dev(dev, class_intf);

  		class_dev_iter_exit(&iter);

  	}

  	mutex_unlock(&parent->p->mutex);

  
  	class_put(parent);
  }

  ssize_t show_class_attr_string(struct class *class,
  			       struct class_attribute *attr, char *buf)

  {
  	struct class_attribute_string *cs;
  	cs = container_of(attr, struct class_attribute_string, attr);
  	return snprintf(buf, PAGE_SIZE, "%s
  ", cs->str);
  }
  
  EXPORT_SYMBOL_GPL(show_class_attr_string);

  struct class_compat {
  	struct kobject *kobj;
  };
  
  /**
   * class_compat_register - register a compatibility class
   * @name: the name of the class
   *
   * Compatibility class are meant as a temporary user-space compatibility
   * workaround when converting a family of class devices to a bus devices.
   */
  struct class_compat *class_compat_register(const char *name)
  {
  	struct class_compat *cls;
  
  	cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
  	if (!cls)
  		return NULL;
  	cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
  	if (!cls->kobj) {
  		kfree(cls);
  		return NULL;
  	}
  	return cls;
  }
  EXPORT_SYMBOL_GPL(class_compat_register);
  
  /**
   * class_compat_unregister - unregister a compatibility class
   * @cls: the class to unregister
   */
  void class_compat_unregister(struct class_compat *cls)
  {
  	kobject_put(cls->kobj);
  	kfree(cls);
  }
  EXPORT_SYMBOL_GPL(class_compat_unregister);
  
  /**
   * class_compat_create_link - create a compatibility class device link to
   *			      a bus device
   * @cls: the compatibility class
   * @dev: the target bus device
   * @device_link: an optional device to which a "device" link should be created
   */
  int class_compat_create_link(struct class_compat *cls, struct device *dev,
  			     struct device *device_link)
  {
  	int error;
  
  	error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
  	if (error)
  		return error;
  
  	/*
  	 * Optionally add a "device" link (typically to the parent), as a
  	 * class device would have one and we want to provide as much
  	 * backwards compatibility as possible.
  	 */
  	if (device_link) {
  		error = sysfs_create_link(&dev->kobj, &device_link->kobj,
  					  "device");
  		if (error)
  			sysfs_remove_link(cls->kobj, dev_name(dev));
  	}
  
  	return error;
  }
  EXPORT_SYMBOL_GPL(class_compat_create_link);
  
  /**
   * class_compat_remove_link - remove a compatibility class device link to
   *			      a bus device
   * @cls: the compatibility class
   * @dev: the target bus device
   * @device_link: an optional device to which a "device" link was previously
   * 		 created
   */
  void class_compat_remove_link(struct class_compat *cls, struct device *dev,
  			      struct device *device_link)
  {
  	if (device_link)
  		sysfs_remove_link(&dev->kobj, "device");
  	sysfs_remove_link(cls->kobj, dev_name(dev));
  }
  EXPORT_SYMBOL_GPL(class_compat_remove_link);

  int __init classes_init(void)
  {

  	class_kset = kset_create_and_add("class", NULL, NULL);
  	if (!class_kset)
  		return -ENOMEM;

  	return 0;
  }
  
  EXPORT_SYMBOL_GPL(class_create_file);
  EXPORT_SYMBOL_GPL(class_remove_file);

  EXPORT_SYMBOL_GPL(class_unregister);

  EXPORT_SYMBOL_GPL(class_destroy);

  EXPORT_SYMBOL_GPL(class_interface_register);
  EXPORT_SYMBOL_GPL(class_interface_unregister);