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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * transport_class.c - implementation of generic transport classes
4 * using attribute_containers
5 *
6 * Copyright (c) 2005 - James Bottomley <[email protected]>
7 *
8 * The basic idea here is to allow any "device controller" (which
9 * would most often be a Host Bus Adapter to use the services of one
10 * or more tranport classes for performing transport specific
11 * services. Transport specific services are things that the generic
12 * command layer doesn't want to know about (speed settings, line
13 * condidtioning, etc), but which the user might be interested in.
14 * Thus, the HBA's use the routines exported by the transport classes
15 * to perform these functions. The transport classes export certain
16 * values to the user via sysfs using attribute containers.
17 *
18 * Note: because not every HBA will care about every transport
19 * attribute, there's a many to one relationship that goes like this:
20 *
21 * transport class<-----attribute container<----class device
22 *
23 * Usually the attribute container is per-HBA, but the design doesn't
24 * mandate that. Although most of the services will be specific to
25 * the actual external storage connection used by the HBA, the generic
26 * transport class is framed entirely in terms of generic devices to
27 * allow it to be used by any physical HBA in the system.
28 */
29#include <linux/export.h>
30#include <linux/attribute_container.h>
31#include <linux/transport_class.h>
32
33static int transport_remove_classdev(struct attribute_container *cont,
34 struct device *dev,
35 struct device *classdev);
36
37/**
38 * transport_class_register - register an initial transport class
39 *
40 * @tclass: a pointer to the transport class structure to be initialised
41 *
42 * The transport class contains an embedded class which is used to
43 * identify it. The caller should initialise this structure with
44 * zeros and then generic class must have been initialised with the
45 * actual transport class unique name. There's a macro
46 * DECLARE_TRANSPORT_CLASS() to do this (declared classes still must
47 * be registered).
48 *
49 * Returns 0 on success or error on failure.
50 */
51int transport_class_register(struct transport_class *tclass)
52{
53 return class_register(&tclass->class);
54}
55EXPORT_SYMBOL_GPL(transport_class_register);
56
57/**
58 * transport_class_unregister - unregister a previously registered class
59 *
60 * @tclass: The transport class to unregister
61 *
62 * Must be called prior to deallocating the memory for the transport
63 * class.
64 */
65void transport_class_unregister(struct transport_class *tclass)
66{
67 class_unregister(&tclass->class);
68}
69EXPORT_SYMBOL_GPL(transport_class_unregister);
70
71static int anon_transport_dummy_function(struct transport_container *tc,
72 struct device *dev,
73 struct device *cdev)
74{
75 /* do nothing */
76 return 0;
77}
78
79/**
80 * anon_transport_class_register - register an anonymous class
81 *
82 * @atc: The anon transport class to register
83 *
84 * The anonymous transport class contains both a transport class and a
85 * container. The idea of an anonymous class is that it never
86 * actually has any device attributes associated with it (and thus
87 * saves on container storage). So it can only be used for triggering
88 * events. Use prezero and then use DECLARE_ANON_TRANSPORT_CLASS() to
89 * initialise the anon transport class storage.
90 */
91void anon_transport_class_register(struct anon_transport_class *atc)
92{
93 atc->container.class = &atc->tclass.class;
94 attribute_container_set_no_classdevs(&atc->container);
95 attribute_container_register(&atc->container);
96 atc->tclass.setup = anon_transport_dummy_function;
97 atc->tclass.remove = anon_transport_dummy_function;
98}
99EXPORT_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 */
109void anon_transport_class_unregister(struct anon_transport_class *atc)
110{
111 if (unlikely(attribute_container_unregister(&atc->container)))
112 BUG();
113}
114EXPORT_SYMBOL_GPL(anon_transport_class_unregister);
115
116static int transport_setup_classdev(struct attribute_container *cont,
117 struct device *dev,
118 struct device *classdev)
119{
120 struct transport_class *tclass = class_to_transport_class(cont->class);
121 struct transport_container *tcont = attribute_container_to_transport_container(cont);
122
123 if (tclass->setup)
124 tclass->setup(tcont, dev, classdev);
125
126 return 0;
127}
128
129/**
130 * transport_setup_device - declare a new dev for transport class association but don't make it visible yet.
131 * @dev: the generic device representing the entity being added
132 *
133 * Usually, dev represents some component in the HBA system (either
134 * the HBA itself or a device remote across the HBA bus). This
135 * routine is simply a trigger point to see if any set of transport
136 * classes wishes to associate with the added device. This allocates
137 * storage for the class device and initialises it, but does not yet
138 * add it to the system or add attributes to it (you do this with
139 * transport_add_device). If you have no need for a separate setup
140 * and add operations, use transport_register_device (see
141 * transport_class.h).
142 */
143
144void transport_setup_device(struct device *dev)
145{
146 attribute_container_add_device(dev, transport_setup_classdev);
147}
148EXPORT_SYMBOL_GPL(transport_setup_device);
149
150static int transport_add_class_device(struct attribute_container *cont,
151 struct device *dev,
152 struct device *classdev)
153{
154 struct transport_class *tclass = class_to_transport_class(cont->class);
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)
160 goto err_remove;
161
162 if (tcont->statistics) {
163 error = sysfs_create_group(&classdev->kobj, tcont->statistics);
164 if (error)
165 goto err_del;
166 }
167
168 if (tcont->encryption) {
169 error = sysfs_create_group(&classdev->kobj, tcont->encryption);
170 if (error)
171 goto err_del_statistics;
172 }
173
174 return 0;
175
176err_del_statistics:
177 if (tcont->statistics)
178 sysfs_remove_group(&classdev->kobj, tcont->statistics);
179err_del:
180 attribute_container_class_device_del(classdev);
181err_remove:
182 if (tclass->remove)
183 tclass->remove(tcont, dev, classdev);
184
185 return error;
186}
187
188
189/**
190 * transport_add_device - declare a new dev for transport class association
191 *
192 * @dev: the generic device representing the entity being added
193 *
194 * Usually, dev represents some component in the HBA system (either
195 * the HBA itself or a device remote across the HBA bus). This
196 * routine is simply a trigger point used to add the device to the
197 * system and register attributes for it.
198 */
199int transport_add_device(struct device *dev)
200{
201 return attribute_container_device_trigger_safe(dev,
202 transport_add_class_device,
203 transport_remove_classdev);
204}
205EXPORT_SYMBOL_GPL(transport_add_device);
206
207static int transport_configure(struct attribute_container *cont,
208 struct device *dev,
209 struct device *cdev)
210{
211 struct transport_class *tclass = class_to_transport_class(cont->class);
212 struct transport_container *tcont = attribute_container_to_transport_container(cont);
213
214 if (tclass->configure)
215 tclass->configure(tcont, dev, cdev);
216
217 return 0;
218}
219
220/**
221 * transport_configure_device - configure an already set up device
222 *
223 * @dev: generic device representing device to be configured
224 *
225 * The idea of configure is simply to provide a point within the setup
226 * process to allow the transport class to extract information from a
227 * device after it has been setup. This is used in SCSI because we
228 * have to have a setup device to begin using the HBA, but after we
229 * send the initial inquiry, we use configure to extract the device
230 * parameters. The device need not have been added to be configured.
231 */
232void transport_configure_device(struct device *dev)
233{
234 attribute_container_device_trigger(dev, transport_configure);
235}
236EXPORT_SYMBOL_GPL(transport_configure_device);
237
238static int transport_remove_classdev(struct attribute_container *cont,
239 struct device *dev,
240 struct device *classdev)
241{
242 struct transport_container *tcont =
243 attribute_container_to_transport_container(cont);
244 struct transport_class *tclass = class_to_transport_class(cont->class);
245
246 if (tclass->remove)
247 tclass->remove(tcont, dev, classdev);
248
249 if (tclass->remove != anon_transport_dummy_function) {
250 if (tcont->statistics)
251 sysfs_remove_group(&classdev->kobj, tcont->statistics);
252 if (tcont->encryption)
253 sysfs_remove_group(&classdev->kobj, tcont->encryption);
254 attribute_container_class_device_del(classdev);
255 }
256
257 return 0;
258}
259
260
261/**
262 * transport_remove_device - remove the visibility of a device
263 *
264 * @dev: generic device to remove
265 *
266 * This call removes the visibility of the device (to the user from
267 * sysfs), but does not destroy it. To eliminate a device entirely
268 * you must also call transport_destroy_device. If you don't need to
269 * do remove and destroy as separate operations, use
270 * transport_unregister_device() (see transport_class.h) which will
271 * perform both calls for you.
272 */
273void transport_remove_device(struct device *dev)
274{
275 attribute_container_device_trigger(dev, transport_remove_classdev);
276}
277EXPORT_SYMBOL_GPL(transport_remove_device);
278
279static void transport_destroy_classdev(struct attribute_container *cont,
280 struct device *dev,
281 struct device *classdev)
282{
283 struct transport_class *tclass = class_to_transport_class(cont->class);
284
285 if (tclass->remove != anon_transport_dummy_function)
286 put_device(classdev);
287}
288
289
290/**
291 * transport_destroy_device - destroy a removed device
292 *
293 * @dev: device to eliminate from the transport class.
294 *
295 * This call triggers the elimination of storage associated with the
296 * transport classdev. Note: all it really does is relinquish a
297 * reference to the classdev. The memory will not be freed until the
298 * last reference goes to zero. Note also that the classdev retains a
299 * reference count on dev, so dev too will remain for as long as the
300 * transport class device remains around.
301 */
302void transport_destroy_device(struct device *dev)
303{
304 attribute_container_remove_device(dev, transport_destroy_classdev);
305}
306EXPORT_SYMBOL_GPL(transport_destroy_device);