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