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
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(class: &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(class: &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 */
91int anon_transport_class_register(struct anon_transport_class *atc)
92{
93 int error;
94 atc->container.class = &atc->tclass.class;
95 attribute_container_set_no_classdevs(atc: &atc->container);
96 error = attribute_container_register(cont: &atc->container);
97 if (error)
98 return error;
99 atc->tclass.setup = anon_transport_dummy_function;
100 atc->tclass.remove = anon_transport_dummy_function;
101 return 0;
102}
103EXPORT_SYMBOL_GPL(anon_transport_class_register);
104
105/**
106 * anon_transport_class_unregister - unregister an anon class
107 *
108 * @atc: Pointer to the anon transport class to unregister
109 *
110 * Must be called prior to deallocating the memory for the anon
111 * transport class.
112 */
113void anon_transport_class_unregister(struct anon_transport_class *atc)
114{
115 if (unlikely(attribute_container_unregister(&atc->container)))
116 BUG();
117}
118EXPORT_SYMBOL_GPL(anon_transport_class_unregister);
119
120static int transport_setup_classdev(struct attribute_container *cont,
121 struct device *dev,
122 struct device *classdev)
123{
124 struct transport_class *tclass = class_to_transport_class(cont->class);
125 struct transport_container *tcont = attribute_container_to_transport_container(cont);
126
127 if (tclass->setup)
128 tclass->setup(tcont, dev, classdev);
129
130 return 0;
131}
132
133/**
134 * transport_setup_device - declare a new dev for transport class association but don't make it visible yet.
135 * @dev: the generic device representing the entity being added
136 *
137 * Usually, dev represents some component in the HBA system (either
138 * the HBA itself or a device remote across the HBA bus). This
139 * routine is simply a trigger point to see if any set of transport
140 * classes wishes to associate with the added device. This allocates
141 * storage for the class device and initialises it, but does not yet
142 * add it to the system or add attributes to it (you do this with
143 * transport_add_device). If you have no need for a separate setup
144 * and add operations, use transport_register_device (see
145 * transport_class.h).
146 */
147
148void transport_setup_device(struct device *dev)
149{
150 attribute_container_add_device(dev, fn: transport_setup_classdev);
151}
152EXPORT_SYMBOL_GPL(transport_setup_device);
153
154static int transport_add_class_device(struct attribute_container *cont,
155 struct device *dev,
156 struct device *classdev)
157{
158 struct transport_class *tclass = class_to_transport_class(cont->class);
159 int error = attribute_container_add_class_device(classdev);
160 struct transport_container *tcont =
161 attribute_container_to_transport_container(cont);
162
163 if (error)
164 goto err_remove;
165
166 if (tcont->statistics) {
167 error = sysfs_create_group(kobj: &classdev->kobj, grp: tcont->statistics);
168 if (error)
169 goto err_del;
170 }
171
172 return 0;
173
174err_del:
175 attribute_container_class_device_del(classdev);
176err_remove:
177 if (tclass->remove)
178 tclass->remove(tcont, dev, classdev);
179
180 return error;
181}
182
183
184/**
185 * transport_add_device - declare a new dev for transport class association
186 *
187 * @dev: the generic device representing the entity being added
188 *
189 * Usually, dev represents some component in the HBA system (either
190 * the HBA itself or a device remote across the HBA bus). This
191 * routine is simply a trigger point used to add the device to the
192 * system and register attributes for it.
193 */
194int transport_add_device(struct device *dev)
195{
196 return attribute_container_device_trigger_safe(dev,
197 fn: transport_add_class_device,
198 undo: transport_remove_classdev);
199}
200EXPORT_SYMBOL_GPL(transport_add_device);
201
202static int transport_configure(struct attribute_container *cont,
203 struct device *dev,
204 struct device *cdev)
205{
206 struct transport_class *tclass = class_to_transport_class(cont->class);
207 struct transport_container *tcont = attribute_container_to_transport_container(cont);
208
209 if (tclass->configure)
210 tclass->configure(tcont, dev, cdev);
211
212 return 0;
213}
214
215/**
216 * transport_configure_device - configure an already set up device
217 *
218 * @dev: generic device representing device to be configured
219 *
220 * The idea of configure is simply to provide a point within the setup
221 * process to allow the transport class to extract information from a
222 * device after it has been setup. This is used in SCSI because we
223 * have to have a setup device to begin using the HBA, but after we
224 * send the initial inquiry, we use configure to extract the device
225 * parameters. The device need not have been added to be configured.
226 */
227void transport_configure_device(struct device *dev)
228{
229 attribute_container_device_trigger(dev, fn: transport_configure);
230}
231EXPORT_SYMBOL_GPL(transport_configure_device);
232
233static int transport_remove_classdev(struct attribute_container *cont,
234 struct device *dev,
235 struct device *classdev)
236{
237 struct transport_container *tcont =
238 attribute_container_to_transport_container(cont);
239 struct transport_class *tclass = class_to_transport_class(cont->class);
240
241 if (tclass->remove)
242 tclass->remove(tcont, dev, classdev);
243
244 if (tclass->remove != anon_transport_dummy_function) {
245 if (tcont->statistics)
246 sysfs_remove_group(kobj: &classdev->kobj, grp: tcont->statistics);
247 attribute_container_class_device_del(classdev);
248 }
249
250 return 0;
251}
252
253
254/**
255 * transport_remove_device - remove the visibility of a device
256 *
257 * @dev: generic device to remove
258 *
259 * This call removes the visibility of the device (to the user from
260 * sysfs), but does not destroy it. To eliminate a device entirely
261 * you must also call transport_destroy_device. If you don't need to
262 * do remove and destroy as separate operations, use
263 * transport_unregister_device() (see transport_class.h) which will
264 * perform both calls for you.
265 */
266void transport_remove_device(struct device *dev)
267{
268 attribute_container_device_trigger(dev, fn: transport_remove_classdev);
269}
270EXPORT_SYMBOL_GPL(transport_remove_device);
271
272static void transport_destroy_classdev(struct attribute_container *cont,
273 struct device *dev,
274 struct device *classdev)
275{
276 struct transport_class *tclass = class_to_transport_class(cont->class);
277
278 if (tclass->remove != anon_transport_dummy_function)
279 put_device(dev: classdev);
280}
281
282
283/**
284 * transport_destroy_device - destroy a removed device
285 *
286 * @dev: device to eliminate from the transport class.
287 *
288 * This call triggers the elimination of storage associated with the
289 * transport classdev. Note: all it really does is relinquish a
290 * reference to the classdev. The memory will not be freed until the
291 * last reference goes to zero. Note also that the classdev retains a
292 * reference count on dev, so dev too will remain for as long as the
293 * transport class device remains around.
294 */
295void transport_destroy_device(struct device *dev)
296{
297 attribute_container_remove_device(dev, fn: transport_destroy_classdev);
298}
299EXPORT_SYMBOL_GPL(transport_destroy_device);
300