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 <James.Bottomley@steeleye.com>
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
33 static 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 */
transport_class_register(struct transport_class * tclass)51 int transport_class_register(struct transport_class *tclass)
52 {
53 return class_register(&tclass->class);
54 }
55 EXPORT_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 */
transport_class_unregister(struct transport_class * tclass)65 void transport_class_unregister(struct transport_class *tclass)
66 {
67 class_unregister(&tclass->class);
68 }
69 EXPORT_SYMBOL_GPL(transport_class_unregister);
70
anon_transport_dummy_function(struct transport_container * tc,struct device * dev,struct device * cdev)71 static 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 */
anon_transport_class_register(struct anon_transport_class * atc)91 void 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 }
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 */
anon_transport_class_unregister(struct anon_transport_class * atc)109 void anon_transport_class_unregister(struct anon_transport_class *atc)
110 {
111 if (unlikely(attribute_container_unregister(&atc->container)))
112 BUG();
113 }
114 EXPORT_SYMBOL_GPL(anon_transport_class_unregister);
115
transport_setup_classdev(struct attribute_container * cont,struct device * dev,struct device * classdev)116 static 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
transport_setup_device(struct device * dev)144 void transport_setup_device(struct device *dev)
145 {
146 attribute_container_add_device(dev, transport_setup_classdev);
147 }
148 EXPORT_SYMBOL_GPL(transport_setup_device);
149
transport_add_class_device(struct attribute_container * cont,struct device * dev,struct device * classdev)150 static 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;
172 }
173
174 return 0;
175
176 err_del:
177 attribute_container_class_device_del(classdev);
178 err_remove:
179 if (tclass->remove)
180 tclass->remove(tcont, dev, classdev);
181
182 return error;
183 }
184
185
186 /**
187 * transport_add_device - declare a new dev for transport class association
188 *
189 * @dev: the generic device representing the entity being added
190 *
191 * Usually, dev represents some component in the HBA system (either
192 * the HBA itself or a device remote across the HBA bus). This
193 * routine is simply a trigger point used to add the device to the
194 * system and register attributes for it.
195 */
transport_add_device(struct device * dev)196 int transport_add_device(struct device *dev)
197 {
198 return attribute_container_device_trigger_safe(dev,
199 transport_add_class_device,
200 transport_remove_classdev);
201 }
202 EXPORT_SYMBOL_GPL(transport_add_device);
203
transport_configure(struct attribute_container * cont,struct device * dev,struct device * cdev)204 static int transport_configure(struct attribute_container *cont,
205 struct device *dev,
206 struct device *cdev)
207 {
208 struct transport_class *tclass = class_to_transport_class(cont->class);
209 struct transport_container *tcont = attribute_container_to_transport_container(cont);
210
211 if (tclass->configure)
212 tclass->configure(tcont, dev, cdev);
213
214 return 0;
215 }
216
217 /**
218 * transport_configure_device - configure an already set up device
219 *
220 * @dev: generic device representing device to be configured
221 *
222 * The idea of configure is simply to provide a point within the setup
223 * process to allow the transport class to extract information from a
224 * device after it has been setup. This is used in SCSI because we
225 * have to have a setup device to begin using the HBA, but after we
226 * send the initial inquiry, we use configure to extract the device
227 * parameters. The device need not have been added to be configured.
228 */
transport_configure_device(struct device * dev)229 void transport_configure_device(struct device *dev)
230 {
231 attribute_container_device_trigger(dev, transport_configure);
232 }
233 EXPORT_SYMBOL_GPL(transport_configure_device);
234
transport_remove_classdev(struct attribute_container * cont,struct device * dev,struct device * classdev)235 static int transport_remove_classdev(struct attribute_container *cont,
236 struct device *dev,
237 struct device *classdev)
238 {
239 struct transport_container *tcont =
240 attribute_container_to_transport_container(cont);
241 struct transport_class *tclass = class_to_transport_class(cont->class);
242
243 if (tclass->remove)
244 tclass->remove(tcont, dev, classdev);
245
246 if (tclass->remove != anon_transport_dummy_function) {
247 if (tcont->statistics)
248 sysfs_remove_group(&classdev->kobj, tcont->statistics);
249 if (tcont->encryption)
250 sysfs_remove_group(&classdev->kobj, tcont->encryption);
251 attribute_container_class_device_del(classdev);
252 }
253
254 return 0;
255 }
256
257
258 /**
259 * transport_remove_device - remove the visibility of a device
260 *
261 * @dev: generic device to remove
262 *
263 * This call removes the visibility of the device (to the user from
264 * sysfs), but does not destroy it. To eliminate a device entirely
265 * you must also call transport_destroy_device. If you don't need to
266 * do remove and destroy as separate operations, use
267 * transport_unregister_device() (see transport_class.h) which will
268 * perform both calls for you.
269 */
transport_remove_device(struct device * dev)270 void transport_remove_device(struct device *dev)
271 {
272 attribute_container_device_trigger(dev, transport_remove_classdev);
273 }
274 EXPORT_SYMBOL_GPL(transport_remove_device);
275
transport_destroy_classdev(struct attribute_container * cont,struct device * dev,struct device * classdev)276 static void transport_destroy_classdev(struct attribute_container *cont,
277 struct device *dev,
278 struct device *classdev)
279 {
280 struct transport_class *tclass = class_to_transport_class(cont->class);
281
282 if (tclass->remove != anon_transport_dummy_function)
283 put_device(classdev);
284 }
285
286
287 /**
288 * transport_destroy_device - destroy a removed device
289 *
290 * @dev: device to eliminate from the transport class.
291 *
292 * This call triggers the elimination of storage associated with the
293 * transport classdev. Note: all it really does is relinquish a
294 * reference to the classdev. The memory will not be freed until the
295 * last reference goes to zero. Note also that the classdev retains a
296 * reference count on dev, so dev too will remain for as long as the
297 * transport class device remains around.
298 */
transport_destroy_device(struct device * dev)299 void transport_destroy_device(struct device *dev)
300 {
301 attribute_container_remove_device(dev, transport_destroy_classdev);
302 }
303 EXPORT_SYMBOL_GPL(transport_destroy_device);
304