280 lines
9.3 KiB
C
280 lines
9.3 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* transport_class.c - implementation of generic transport classes
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* using attribute_containers
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*
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* Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com>
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*
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* The basic idea here is to allow any "device controller" (which
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* would most often be a Host Bus Adapter to use the services of one
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* or more tranport classes for performing transport specific
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* services. Transport specific services are things that the generic
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* command layer doesn't want to know about (speed settings, line
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* condidtioning, etc), but which the user might be interested in.
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* Thus, the HBA's use the routines exported by the transport classes
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* to perform these functions. The transport classes export certain
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* values to the user via sysfs using attribute containers.
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*
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* Note: because not every HBA will care about every transport
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* attribute, there's a many to one relationship that goes like this:
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*
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* transport class<-----attribute container<----class device
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*
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* Usually the attribute container is per-HBA, but the design doesn't
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* mandate that. Although most of the services will be specific to
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* the actual external storage connection used by the HBA, the generic
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* transport class is framed entirely in terms of generic devices to
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* allow it to be used by any physical HBA in the system.
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*/
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#include <linux/export.h>
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#include <linux/attribute_container.h>
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#include <linux/transport_class.h>
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/**
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* transport_class_register - register an initial transport class
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*
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* @tclass: a pointer to the transport class structure to be initialised
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*
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* The transport class contains an embedded class which is used to
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* identify it. The caller should initialise this structure with
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* zeros and then generic class must have been initialised with the
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* actual transport class unique name. There's a macro
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* DECLARE_TRANSPORT_CLASS() to do this (declared classes still must
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* be registered).
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*
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* Returns 0 on success or error on failure.
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*/
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int transport_class_register(struct transport_class *tclass)
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{
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return class_register(&tclass->class);
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}
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EXPORT_SYMBOL_GPL(transport_class_register);
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/**
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* transport_class_unregister - unregister a previously registered class
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*
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* @tclass: The transport class to unregister
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*
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* Must be called prior to deallocating the memory for the transport
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* class.
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*/
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void transport_class_unregister(struct transport_class *tclass)
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{
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class_unregister(&tclass->class);
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}
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EXPORT_SYMBOL_GPL(transport_class_unregister);
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static int anon_transport_dummy_function(struct transport_container *tc,
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struct device *dev,
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struct device *cdev)
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{
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/* do nothing */
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return 0;
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}
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/**
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* anon_transport_class_register - register an anonymous class
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*
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* @atc: The anon transport class to register
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*
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* The anonymous transport class contains both a transport class and a
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* container. The idea of an anonymous class is that it never
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* actually has any device attributes associated with it (and thus
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* saves on container storage). So it can only be used for triggering
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* events. Use prezero and then use DECLARE_ANON_TRANSPORT_CLASS() to
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* initialise the anon transport class storage.
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*/
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int anon_transport_class_register(struct anon_transport_class *atc)
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{
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int error;
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atc->container.class = &atc->tclass.class;
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attribute_container_set_no_classdevs(&atc->container);
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error = attribute_container_register(&atc->container);
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if (error)
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return error;
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atc->tclass.setup = anon_transport_dummy_function;
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atc->tclass.remove = anon_transport_dummy_function;
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return 0;
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}
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EXPORT_SYMBOL_GPL(anon_transport_class_register);
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/**
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* anon_transport_class_unregister - unregister an anon class
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*
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* @atc: Pointer to the anon transport class to unregister
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*
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* Must be called prior to deallocating the memory for the anon
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* transport class.
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*/
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void anon_transport_class_unregister(struct anon_transport_class *atc)
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{
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if (unlikely(attribute_container_unregister(&atc->container)))
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BUG();
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}
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EXPORT_SYMBOL_GPL(anon_transport_class_unregister);
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static int transport_setup_classdev(struct attribute_container *cont,
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struct device *dev,
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struct device *classdev)
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{
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struct transport_class *tclass = class_to_transport_class(cont->class);
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struct transport_container *tcont = attribute_container_to_transport_container(cont);
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if (tclass->setup)
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tclass->setup(tcont, dev, classdev);
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return 0;
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}
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/**
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* transport_setup_device - declare a new dev for transport class association but don't make it visible yet.
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* @dev: the generic device representing the entity being added
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*
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* Usually, dev represents some component in the HBA system (either
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* the HBA itself or a device remote across the HBA bus). This
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* routine is simply a trigger point to see if any set of transport
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* classes wishes to associate with the added device. This allocates
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* storage for the class device and initialises it, but does not yet
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* add it to the system or add attributes to it (you do this with
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* transport_add_device). If you have no need for a separate setup
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* and add operations, use transport_register_device (see
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* transport_class.h).
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*/
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void transport_setup_device(struct device *dev)
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{
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attribute_container_add_device(dev, transport_setup_classdev);
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}
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EXPORT_SYMBOL_GPL(transport_setup_device);
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static int transport_add_class_device(struct attribute_container *cont,
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struct device *dev,
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struct device *classdev)
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{
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int error = attribute_container_add_class_device(classdev);
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struct transport_container *tcont =
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attribute_container_to_transport_container(cont);
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if (!error && tcont->statistics)
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error = sysfs_create_group(&classdev->kobj, tcont->statistics);
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return error;
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}
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/**
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* transport_add_device - declare a new dev for transport class association
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*
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* @dev: the generic device representing the entity being added
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*
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* Usually, dev represents some component in the HBA system (either
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* the HBA itself or a device remote across the HBA bus). This
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* routine is simply a trigger point used to add the device to the
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* system and register attributes for it.
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*/
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void transport_add_device(struct device *dev)
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{
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attribute_container_device_trigger(dev, transport_add_class_device);
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}
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EXPORT_SYMBOL_GPL(transport_add_device);
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static int transport_configure(struct attribute_container *cont,
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struct device *dev,
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struct device *cdev)
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{
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struct transport_class *tclass = class_to_transport_class(cont->class);
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struct transport_container *tcont = attribute_container_to_transport_container(cont);
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if (tclass->configure)
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tclass->configure(tcont, dev, cdev);
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return 0;
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}
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/**
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* transport_configure_device - configure an already set up device
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*
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* @dev: generic device representing device to be configured
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*
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* The idea of configure is simply to provide a point within the setup
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* process to allow the transport class to extract information from a
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* device after it has been setup. This is used in SCSI because we
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* have to have a setup device to begin using the HBA, but after we
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* send the initial inquiry, we use configure to extract the device
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* parameters. The device need not have been added to be configured.
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*/
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void transport_configure_device(struct device *dev)
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{
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attribute_container_device_trigger(dev, transport_configure);
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}
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EXPORT_SYMBOL_GPL(transport_configure_device);
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static int transport_remove_classdev(struct attribute_container *cont,
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struct device *dev,
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struct device *classdev)
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{
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struct transport_container *tcont =
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attribute_container_to_transport_container(cont);
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struct transport_class *tclass = class_to_transport_class(cont->class);
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if (tclass->remove)
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tclass->remove(tcont, dev, classdev);
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if (tclass->remove != anon_transport_dummy_function) {
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if (tcont->statistics)
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sysfs_remove_group(&classdev->kobj, tcont->statistics);
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attribute_container_class_device_del(classdev);
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}
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return 0;
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}
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/**
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* transport_remove_device - remove the visibility of a device
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*
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* @dev: generic device to remove
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*
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* This call removes the visibility of the device (to the user from
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* sysfs), but does not destroy it. To eliminate a device entirely
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* you must also call transport_destroy_device. If you don't need to
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* do remove and destroy as separate operations, use
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* transport_unregister_device() (see transport_class.h) which will
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* perform both calls for you.
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*/
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void transport_remove_device(struct device *dev)
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{
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attribute_container_device_trigger(dev, transport_remove_classdev);
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}
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EXPORT_SYMBOL_GPL(transport_remove_device);
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static void transport_destroy_classdev(struct attribute_container *cont,
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struct device *dev,
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struct device *classdev)
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{
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struct transport_class *tclass = class_to_transport_class(cont->class);
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if (tclass->remove != anon_transport_dummy_function)
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put_device(classdev);
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}
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/**
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* transport_destroy_device - destroy a removed device
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*
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* @dev: device to eliminate from the transport class.
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*
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* This call triggers the elimination of storage associated with the
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* transport classdev. Note: all it really does is relinquish a
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* reference to the classdev. The memory will not be freed until the
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* last reference goes to zero. Note also that the classdev retains a
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* reference count on dev, so dev too will remain for as long as the
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* transport class device remains around.
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*/
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void transport_destroy_device(struct device *dev)
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{
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attribute_container_remove_device(dev, transport_destroy_classdev);
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}
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EXPORT_SYMBOL_GPL(transport_destroy_device);
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