/*
   * transport_class.c - implementation of generic transport classes
   *                     using attribute_containers
   *
   * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com>
   *
   * This file is licensed under GPLv2
   *
   * The basic idea here is to allow any "device controller" (which

   * would most often be a Host Bus Adapter to use the services of one

   * or more tranport classes for performing transport specific
   * services.  Transport specific services are things that the generic
   * command layer doesn't want to know about (speed settings, line
   * condidtioning, etc), but which the user might be interested in.
   * Thus, the HBA's use the routines exported by the transport classes
   * to perform these functions.  The transport classes export certain
   * values to the user via sysfs using attribute containers.
   *
   * Note: because not every HBA will care about every transport
   * attribute, there's a many to one relationship that goes like this:
   *
   * transport class<-----attribute container<----class device
   *
   * Usually the attribute container is per-HBA, but the design doesn't
   * mandate that.  Although most of the services will be specific to
   * the actual external storage connection used by the HBA, the generic
   * transport class is framed entirely in terms of generic devices to
   * allow it to be used by any physical HBA in the system.
   */

  #include <linux/export.h>

  #include <linux/attribute_container.h>
  #include <linux/transport_class.h>
  
  /**
   * transport_class_register - register an initial transport class
   *
   * @tclass:	a pointer to the transport class structure to be initialised
   *
   * The transport class contains an embedded class which is used to
   * identify it.  The caller should initialise this structure with
   * zeros and then generic class must have been initialised with the
   * actual transport class unique name.  There's a macro
   * DECLARE_TRANSPORT_CLASS() to do this (declared classes still must
   * be registered).
   *
   * Returns 0 on success or error on failure.
   */
  int transport_class_register(struct transport_class *tclass)
  {
  	return class_register(&tclass->class);
  }
  EXPORT_SYMBOL_GPL(transport_class_register);
  
  /**
   * transport_class_unregister - unregister a previously registered class
   *
   * @tclass: The transport class to unregister
   *
   * Must be called prior to deallocating the memory for the transport
   * class.
   */
  void transport_class_unregister(struct transport_class *tclass)
  {
  	class_unregister(&tclass->class);
  }
  EXPORT_SYMBOL_GPL(transport_class_unregister);

  static int anon_transport_dummy_function(struct transport_container *tc,
  					 struct device *dev,

  					 struct device *cdev)

  {
  	/* do nothing */
  	return 0;
  }
  
  /**
   * anon_transport_class_register - register an anonymous class
   *
   * @atc: The anon transport class to register
   *
   * The anonymous transport class contains both a transport class and a
   * container.  The idea of an anonymous class is that it never
   * actually has any device attributes associated with it (and thus
   * saves on container storage).  So it can only be used for triggering
   * events.  Use prezero and then use DECLARE_ANON_TRANSPORT_CLASS() to
   * initialise the anon transport class storage.
   */
  int anon_transport_class_register(struct anon_transport_class *atc)
  {
  	int error;
  	atc->container.class = &atc->tclass.class;
  	attribute_container_set_no_classdevs(&atc->container);
  	error = attribute_container_register(&atc->container);
  	if (error)
  		return error;
  	atc->tclass.setup = anon_transport_dummy_function;
  	atc->tclass.remove = anon_transport_dummy_function;
  	return 0;
  }
  EXPORT_SYMBOL_GPL(anon_transport_class_register);
  
  /**
   * anon_transport_class_unregister - unregister an anon class
   *
   * @atc: Pointer to the anon transport class to unregister
   *
   * Must be called prior to deallocating the memory for the anon
   * transport class.
   */
  void anon_transport_class_unregister(struct anon_transport_class *atc)
  {

  	if (unlikely(attribute_container_unregister(&atc->container)))
  		BUG();

  }
  EXPORT_SYMBOL_GPL(anon_transport_class_unregister);
  
  static int transport_setup_classdev(struct attribute_container *cont,
  				    struct device *dev,

  				    struct device *classdev)

  {
  	struct transport_class *tclass = class_to_transport_class(cont->class);

  	struct transport_container *tcont = attribute_container_to_transport_container(cont);

  
  	if (tclass->setup)

  		tclass->setup(tcont, dev, classdev);

  
  	return 0;
  }
  
  /**

   * transport_setup_device - declare a new dev for transport class association but don't make it visible yet.

   * @dev: the generic device representing the entity being added
   *
   * Usually, dev represents some component in the HBA system (either
   * the HBA itself or a device remote across the HBA bus).  This
   * routine is simply a trigger point to see if any set of transport
   * classes wishes to associate with the added device.  This allocates
   * storage for the class device and initialises it, but does not yet
   * add it to the system or add attributes to it (you do this with
   * transport_add_device).  If you have no need for a separate setup
   * and add operations, use transport_register_device (see
   * transport_class.h).
   */
  
  void transport_setup_device(struct device *dev)
  {
  	attribute_container_add_device(dev, transport_setup_classdev);
  }
  EXPORT_SYMBOL_GPL(transport_setup_device);
  
  static int transport_add_class_device(struct attribute_container *cont,
  				      struct device *dev,

  				      struct device *classdev)

  {
  	int error = attribute_container_add_class_device(classdev);
  	struct transport_container *tcont = 
  		attribute_container_to_transport_container(cont);
  
  	if (!error && tcont->statistics)
  		error = sysfs_create_group(&classdev->kobj, tcont->statistics);
  
  	return error;
  }
  
  
  /**
   * transport_add_device - declare a new dev for transport class association
   *
   * @dev: the generic device representing the entity being added
   *
   * Usually, dev represents some component in the HBA system (either
   * the HBA itself or a device remote across the HBA bus).  This
   * routine is simply a trigger point used to add the device to the
   * system and register attributes for it.
   */
  
  void transport_add_device(struct device *dev)
  {
  	attribute_container_device_trigger(dev, transport_add_class_device);
  }
  EXPORT_SYMBOL_GPL(transport_add_device);
  
  static int transport_configure(struct attribute_container *cont,

  			       struct device *dev,

  			       struct device *cdev)

  {
  	struct transport_class *tclass = class_to_transport_class(cont->class);

  	struct transport_container *tcont = attribute_container_to_transport_container(cont);

  
  	if (tclass->configure)

  		tclass->configure(tcont, dev, cdev);

  
  	return 0;
  }
  
  /**
   * transport_configure_device - configure an already set up device
   *
   * @dev: generic device representing device to be configured
   *
   * The idea of configure is simply to provide a point within the setup
   * process to allow the transport class to extract information from a
   * device after it has been setup.  This is used in SCSI because we
   * have to have a setup device to begin using the HBA, but after we
   * send the initial inquiry, we use configure to extract the device
   * parameters.  The device need not have been added to be configured.
   */
  void transport_configure_device(struct device *dev)
  {

  	attribute_container_device_trigger(dev, transport_configure);

  }
  EXPORT_SYMBOL_GPL(transport_configure_device);
  
  static int transport_remove_classdev(struct attribute_container *cont,
  				     struct device *dev,

  				     struct device *classdev)

  {
  	struct transport_container *tcont = 
  		attribute_container_to_transport_container(cont);
  	struct transport_class *tclass = class_to_transport_class(cont->class);
  
  	if (tclass->remove)

  		tclass->remove(tcont, dev, classdev);

  
  	if (tclass->remove != anon_transport_dummy_function) {
  		if (tcont->statistics)
  			sysfs_remove_group(&classdev->kobj, tcont->statistics);
  		attribute_container_class_device_del(classdev);
  	}
  
  	return 0;
  }
  
  
  /**
   * transport_remove_device - remove the visibility of a device
   *
   * @dev: generic device to remove
   *
   * This call removes the visibility of the device (to the user from
   * sysfs), but does not destroy it.  To eliminate a device entirely
   * you must also call transport_destroy_device.  If you don't need to
   * do remove and destroy as separate operations, use
   * transport_unregister_device() (see transport_class.h) which will
   * perform both calls for you.
   */
  void transport_remove_device(struct device *dev)
  {
  	attribute_container_device_trigger(dev, transport_remove_classdev);
  }
  EXPORT_SYMBOL_GPL(transport_remove_device);
  
  static void transport_destroy_classdev(struct attribute_container *cont,
  				      struct device *dev,

  				      struct device *classdev)

  {
  	struct transport_class *tclass = class_to_transport_class(cont->class);
  
  	if (tclass->remove != anon_transport_dummy_function)

  		put_device(classdev);

  }
  
  
  /**
   * transport_destroy_device - destroy a removed device
   *
   * @dev: device to eliminate from the transport class.
   *
   * This call triggers the elimination of storage associated with the
   * transport classdev.  Note: all it really does is relinquish a
   * reference to the classdev.  The memory will not be freed until the
   * last reference goes to zero.  Note also that the classdev retains a
   * reference count on dev, so dev too will remain for as long as the
   * transport class device remains around.
   */
  void transport_destroy_device(struct device *dev)
  {
  	attribute_container_remove_device(dev, transport_destroy_classdev);
  }
  EXPORT_SYMBOL_GPL(transport_destroy_device);