// SPDX-License-Identifier: GPL-2.0 /* * transport_class.c - implementation of generic transport classes * using attribute_containers * * Copyright (c) 2005 - James Bottomley <[email protected]> * * 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> static int transport_remove_classdev(struct attribute_container *cont, struct device *dev, struct device *classdev); /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * 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) { … } EXPORT_SYMBOL_GPL(…); static int anon_transport_dummy_function(struct transport_container *tc, struct device *dev, struct device *cdev) { … } /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * 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) { … } EXPORT_SYMBOL_GPL(…); static int transport_setup_classdev(struct attribute_container *cont, struct device *dev, struct device *classdev) { … } /** * 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) { … } EXPORT_SYMBOL_GPL(…); static int transport_add_class_device(struct attribute_container *cont, struct device *dev, struct device *classdev) { … } /** * 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. */ int transport_add_device(struct device *dev) { … } EXPORT_SYMBOL_GPL(…); static int transport_configure(struct attribute_container *cont, struct device *dev, struct device *cdev) { … } /** * 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) { … } EXPORT_SYMBOL_GPL(…); static int transport_remove_classdev(struct attribute_container *cont, struct device *dev, struct device *classdev) { … } /** * 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) { … } EXPORT_SYMBOL_GPL(…); static void transport_destroy_classdev(struct attribute_container *cont, struct device *dev, struct 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) { … } EXPORT_SYMBOL_GPL(…);
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