Root/drivers/base/transport_class.c

1/*
2 * transport_class.c - implementation of generic transport classes
3 * using attribute_containers
4 *
5 * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com>
6 *
7 * This file is licensed under GPLv2
8 *
9 * The basic idea here is to allow any "device controller" (which
10 * would most often be a Host Bus Adapter to use the services of one
11 * or more tranport classes for performing transport specific
12 * services. Transport specific services are things that the generic
13 * command layer doesn't want to know about (speed settings, line
14 * condidtioning, etc), but which the user might be interested in.
15 * Thus, the HBA's use the routines exported by the transport classes
16 * to perform these functions. The transport classes export certain
17 * values to the user via sysfs using attribute containers.
18 *
19 * Note: because not every HBA will care about every transport
20 * attribute, there's a many to one relationship that goes like this:
21 *
22 * transport class<-----attribute container<----class device
23 *
24 * Usually the attribute container is per-HBA, but the design doesn't
25 * mandate that. Although most of the services will be specific to
26 * the actual external storage connection used by the HBA, the generic
27 * transport class is framed entirely in terms of generic devices to
28 * allow it to be used by any physical HBA in the system.
29 */
30#include <linux/export.h>
31#include <linux/attribute_container.h>
32#include <linux/transport_class.h>
33
34/**
35 * transport_class_register - register an initial transport class
36 *
37 * @tclass: a pointer to the transport class structure to be initialised
38 *
39 * The transport class contains an embedded class which is used to
40 * identify it. The caller should initialise this structure with
41 * zeros and then generic class must have been initialised with the
42 * actual transport class unique name. There's a macro
43 * DECLARE_TRANSPORT_CLASS() to do this (declared classes still must
44 * be registered).
45 *
46 * Returns 0 on success or error on failure.
47 */
48int transport_class_register(struct transport_class *tclass)
49{
50    return class_register(&tclass->class);
51}
52EXPORT_SYMBOL_GPL(transport_class_register);
53
54/**
55 * transport_class_unregister - unregister a previously registered class
56 *
57 * @tclass: The transport class to unregister
58 *
59 * Must be called prior to deallocating the memory for the transport
60 * class.
61 */
62void transport_class_unregister(struct transport_class *tclass)
63{
64    class_unregister(&tclass->class);
65}
66EXPORT_SYMBOL_GPL(transport_class_unregister);
67
68static int anon_transport_dummy_function(struct transport_container *tc,
69                     struct device *dev,
70                     struct device *cdev)
71{
72    /* do nothing */
73    return 0;
74}
75
76/**
77 * anon_transport_class_register - register an anonymous class
78 *
79 * @atc: The anon transport class to register
80 *
81 * The anonymous transport class contains both a transport class and a
82 * container. The idea of an anonymous class is that it never
83 * actually has any device attributes associated with it (and thus
84 * saves on container storage). So it can only be used for triggering
85 * events. Use prezero and then use DECLARE_ANON_TRANSPORT_CLASS() to
86 * initialise the anon transport class storage.
87 */
88int anon_transport_class_register(struct anon_transport_class *atc)
89{
90    int error;
91    atc->container.class = &atc->tclass.class;
92    attribute_container_set_no_classdevs(&atc->container);
93    error = attribute_container_register(&atc->container);
94    if (error)
95        return error;
96    atc->tclass.setup = anon_transport_dummy_function;
97    atc->tclass.remove = anon_transport_dummy_function;
98    return 0;
99}
100EXPORT_SYMBOL_GPL(anon_transport_class_register);
101
102/**
103 * anon_transport_class_unregister - unregister an anon class
104 *
105 * @atc: Pointer to the anon transport class to unregister
106 *
107 * Must be called prior to deallocating the memory for the anon
108 * transport class.
109 */
110void anon_transport_class_unregister(struct anon_transport_class *atc)
111{
112    if (unlikely(attribute_container_unregister(&atc->container)))
113        BUG();
114}
115EXPORT_SYMBOL_GPL(anon_transport_class_unregister);
116
117static int transport_setup_classdev(struct attribute_container *cont,
118                    struct device *dev,
119                    struct device *classdev)
120{
121    struct transport_class *tclass = class_to_transport_class(cont->class);
122    struct transport_container *tcont = attribute_container_to_transport_container(cont);
123
124    if (tclass->setup)
125        tclass->setup(tcont, dev, classdev);
126
127    return 0;
128}
129
130/**
131 * transport_setup_device - declare a new dev for transport class association but don't make it visible yet.
132 * @dev: the generic device representing the entity being added
133 *
134 * Usually, dev represents some component in the HBA system (either
135 * the HBA itself or a device remote across the HBA bus). This
136 * routine is simply a trigger point to see if any set of transport
137 * classes wishes to associate with the added device. This allocates
138 * storage for the class device and initialises it, but does not yet
139 * add it to the system or add attributes to it (you do this with
140 * transport_add_device). If you have no need for a separate setup
141 * and add operations, use transport_register_device (see
142 * transport_class.h).
143 */
144
145void transport_setup_device(struct device *dev)
146{
147    attribute_container_add_device(dev, transport_setup_classdev);
148}
149EXPORT_SYMBOL_GPL(transport_setup_device);
150
151static int transport_add_class_device(struct attribute_container *cont,
152                      struct device *dev,
153                      struct device *classdev)
154{
155    int error = attribute_container_add_class_device(classdev);
156    struct transport_container *tcont =
157        attribute_container_to_transport_container(cont);
158
159    if (!error && tcont->statistics)
160        error = sysfs_create_group(&classdev->kobj, tcont->statistics);
161
162    return error;
163}
164
165
166/**
167 * transport_add_device - declare a new dev for transport class association
168 *
169 * @dev: the generic device representing the entity being added
170 *
171 * Usually, dev represents some component in the HBA system (either
172 * the HBA itself or a device remote across the HBA bus). This
173 * routine is simply a trigger point used to add the device to the
174 * system and register attributes for it.
175 */
176
177void transport_add_device(struct device *dev)
178{
179    attribute_container_device_trigger(dev, transport_add_class_device);
180}
181EXPORT_SYMBOL_GPL(transport_add_device);
182
183static int transport_configure(struct attribute_container *cont,
184                   struct device *dev,
185                   struct device *cdev)
186{
187    struct transport_class *tclass = class_to_transport_class(cont->class);
188    struct transport_container *tcont = attribute_container_to_transport_container(cont);
189
190    if (tclass->configure)
191        tclass->configure(tcont, dev, cdev);
192
193    return 0;
194}
195
196/**
197 * transport_configure_device - configure an already set up device
198 *
199 * @dev: generic device representing device to be configured
200 *
201 * The idea of configure is simply to provide a point within the setup
202 * process to allow the transport class to extract information from a
203 * device after it has been setup. This is used in SCSI because we
204 * have to have a setup device to begin using the HBA, but after we
205 * send the initial inquiry, we use configure to extract the device
206 * parameters. The device need not have been added to be configured.
207 */
208void transport_configure_device(struct device *dev)
209{
210    attribute_container_device_trigger(dev, transport_configure);
211}
212EXPORT_SYMBOL_GPL(transport_configure_device);
213
214static int transport_remove_classdev(struct attribute_container *cont,
215                     struct device *dev,
216                     struct device *classdev)
217{
218    struct transport_container *tcont =
219        attribute_container_to_transport_container(cont);
220    struct transport_class *tclass = class_to_transport_class(cont->class);
221
222    if (tclass->remove)
223        tclass->remove(tcont, dev, classdev);
224
225    if (tclass->remove != anon_transport_dummy_function) {
226        if (tcont->statistics)
227            sysfs_remove_group(&classdev->kobj, tcont->statistics);
228        attribute_container_class_device_del(classdev);
229    }
230
231    return 0;
232}
233
234
235/**
236 * transport_remove_device - remove the visibility of a device
237 *
238 * @dev: generic device to remove
239 *
240 * This call removes the visibility of the device (to the user from
241 * sysfs), but does not destroy it. To eliminate a device entirely
242 * you must also call transport_destroy_device. If you don't need to
243 * do remove and destroy as separate operations, use
244 * transport_unregister_device() (see transport_class.h) which will
245 * perform both calls for you.
246 */
247void transport_remove_device(struct device *dev)
248{
249    attribute_container_device_trigger(dev, transport_remove_classdev);
250}
251EXPORT_SYMBOL_GPL(transport_remove_device);
252
253static void transport_destroy_classdev(struct attribute_container *cont,
254                      struct device *dev,
255                      struct device *classdev)
256{
257    struct transport_class *tclass = class_to_transport_class(cont->class);
258
259    if (tclass->remove != anon_transport_dummy_function)
260        put_device(classdev);
261}
262
263
264/**
265 * transport_destroy_device - destroy a removed device
266 *
267 * @dev: device to eliminate from the transport class.
268 *
269 * This call triggers the elimination of storage associated with the
270 * transport classdev. Note: all it really does is relinquish a
271 * reference to the classdev. The memory will not be freed until the
272 * last reference goes to zero. Note also that the classdev retains a
273 * reference count on dev, so dev too will remain for as long as the
274 * transport class device remains around.
275 */
276void transport_destroy_device(struct device *dev)
277{
278    attribute_container_remove_device(dev, transport_destroy_classdev);
279}
280EXPORT_SYMBOL_GPL(transport_destroy_device);
281

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