1// SPDX-License-Identifier: GPL-2.0
2/*
3 * attribute_container.c - implementation of a simple container for classes
4 *
5 * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com>
6 *
7 * The basic idea here is to enable a device to be attached to an
8 * aritrary numer of classes without having to allocate storage for them.
9 * Instead, the contained classes select the devices they need to attach
10 * to via a matching function.
11 */
12
13#include <linux/attribute_container.h>
14#include <linux/device.h>
15#include <linux/kernel.h>
16#include <linux/slab.h>
17#include <linux/list.h>
18#include <linux/module.h>
19#include <linux/mutex.h>
20
21#include "base.h"
22
23/* This is a private structure used to tie the classdev and the
24 * container .. it should never be visible outside this file */
25struct internal_container {
26 struct klist_node node;
27 struct attribute_container *cont;
28 struct device classdev;
29};
30
31static void internal_container_klist_get(struct klist_node *n)
32{
33 struct internal_container *ic =
34 container_of(n, struct internal_container, node);
35 get_device(&ic->classdev);
36}
37
38static void internal_container_klist_put(struct klist_node *n)
39{
40 struct internal_container *ic =
41 container_of(n, struct internal_container, node);
42 put_device(&ic->classdev);
43}
44
45
46/**
47 * attribute_container_classdev_to_container - given a classdev, return the container
48 *
49 * @classdev: the class device created by attribute_container_add_device.
50 *
51 * Returns the container associated with this classdev.
52 */
53struct attribute_container *
54attribute_container_classdev_to_container(struct device *classdev)
55{
56 struct internal_container *ic =
57 container_of(classdev, struct internal_container, classdev);
58 return ic->cont;
59}
60EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);
61
62static LIST_HEAD(attribute_container_list);
63
64static DEFINE_MUTEX(attribute_container_mutex);
65
66/**
67 * attribute_container_register - register an attribute container
68 *
69 * @cont: The container to register. This must be allocated by the
70 * callee and should also be zeroed by it.
71 */
72int
73attribute_container_register(struct attribute_container *cont)
74{
75 INIT_LIST_HEAD(&cont->node);
76 klist_init(&cont->containers, internal_container_klist_get,
77 internal_container_klist_put);
78
79 mutex_lock(&attribute_container_mutex);
80 list_add_tail(&cont->node, &attribute_container_list);
81 mutex_unlock(&attribute_container_mutex);
82
83 return 0;
84}
85EXPORT_SYMBOL_GPL(attribute_container_register);
86
87/**
88 * attribute_container_unregister - remove a container registration
89 *
90 * @cont: previously registered container to remove
91 */
92int
93attribute_container_unregister(struct attribute_container *cont)
94{
95 int retval = -EBUSY;
96
97 mutex_lock(&attribute_container_mutex);
98 spin_lock(&cont->containers.k_lock);
99 if (!list_empty(&cont->containers.k_list))
100 goto out;
101 retval = 0;
102 list_del(&cont->node);
103 out:
104 spin_unlock(&cont->containers.k_lock);
105 mutex_unlock(&attribute_container_mutex);
106 return retval;
107
108}
109EXPORT_SYMBOL_GPL(attribute_container_unregister);
110
111/* private function used as class release */
112static void attribute_container_release(struct device *classdev)
113{
114 struct internal_container *ic
115 = container_of(classdev, struct internal_container, classdev);
116 struct device *dev = classdev->parent;
117
118 kfree(ic);
119 put_device(dev);
120}
121
122/**
123 * attribute_container_add_device - see if any container is interested in dev
124 *
125 * @dev: device to add attributes to
126 * @fn: function to trigger addition of class device.
127 *
128 * This function allocates storage for the class device(s) to be
129 * attached to dev (one for each matching attribute_container). If no
130 * fn is provided, the code will simply register the class device via
131 * device_add. If a function is provided, it is expected to add
132 * the class device at the appropriate time. One of the things that
133 * might be necessary is to allocate and initialise the classdev and
134 * then add it a later time. To do this, call this routine for
135 * allocation and initialisation and then use
136 * attribute_container_device_trigger() to call device_add() on
137 * it. Note: after this, the class device contains a reference to dev
138 * which is not relinquished until the release of the classdev.
139 */
140void
141attribute_container_add_device(struct device *dev,
142 int (*fn)(struct attribute_container *,
143 struct device *,
144 struct device *))
145{
146 struct attribute_container *cont;
147
148 mutex_lock(&attribute_container_mutex);
149 list_for_each_entry(cont, &attribute_container_list, node) {
150 struct internal_container *ic;
151
152 if (attribute_container_no_classdevs(cont))
153 continue;
154
155 if (!cont->match(cont, dev))
156 continue;
157
158 ic = kzalloc(sizeof(*ic), GFP_KERNEL);
159 if (!ic) {
160 dev_err(dev, "failed to allocate class container\n");
161 continue;
162 }
163
164 ic->cont = cont;
165 device_initialize(&ic->classdev);
166 ic->classdev.parent = get_device(dev);
167 ic->classdev.class = cont->class;
168 cont->class->dev_release = attribute_container_release;
169 dev_set_name(&ic->classdev, "%s", dev_name(dev));
170 if (fn)
171 fn(cont, dev, &ic->classdev);
172 else
173 attribute_container_add_class_device(&ic->classdev);
174 klist_add_tail(&ic->node, &cont->containers);
175 }
176 mutex_unlock(&attribute_container_mutex);
177}
178
179/* FIXME: can't break out of this unless klist_iter_exit is also
180 * called before doing the break
181 */
182#define klist_for_each_entry(pos, head, member, iter) \
183 for (klist_iter_init(head, iter); (pos = ({ \
184 struct klist_node *n = klist_next(iter); \
185 n ? container_of(n, typeof(*pos), member) : \
186 ({ klist_iter_exit(iter) ; NULL; }); \
187 })) != NULL;)
188
189
190/**
191 * attribute_container_remove_device - make device eligible for removal.
192 *
193 * @dev: The generic device
194 * @fn: A function to call to remove the device
195 *
196 * This routine triggers device removal. If fn is NULL, then it is
197 * simply done via device_unregister (note that if something
198 * still has a reference to the classdev, then the memory occupied
199 * will not be freed until the classdev is released). If you want a
200 * two phase release: remove from visibility and then delete the
201 * device, then you should use this routine with a fn that calls
202 * device_del() and then use attribute_container_device_trigger()
203 * to do the final put on the classdev.
204 */
205void
206attribute_container_remove_device(struct device *dev,
207 void (*fn)(struct attribute_container *,
208 struct device *,
209 struct device *))
210{
211 struct attribute_container *cont;
212
213 mutex_lock(&attribute_container_mutex);
214 list_for_each_entry(cont, &attribute_container_list, node) {
215 struct internal_container *ic;
216 struct klist_iter iter;
217
218 if (attribute_container_no_classdevs(cont))
219 continue;
220
221 if (!cont->match(cont, dev))
222 continue;
223
224 klist_for_each_entry(ic, &cont->containers, node, &iter) {
225 if (dev != ic->classdev.parent)
226 continue;
227 klist_del(&ic->node);
228 if (fn)
229 fn(cont, dev, &ic->classdev);
230 else {
231 attribute_container_remove_attrs(&ic->classdev);
232 device_unregister(&ic->classdev);
233 }
234 }
235 }
236 mutex_unlock(&attribute_container_mutex);
237}
238
239/**
240 * attribute_container_device_trigger - execute a trigger for each matching classdev
241 *
242 * @dev: The generic device to run the trigger for
243 * @fn the function to execute for each classdev.
244 *
245 * This function is for executing a trigger when you need to know both
246 * the container and the classdev. If you only care about the
247 * container, then use attribute_container_trigger() instead.
248 */
249void
250attribute_container_device_trigger(struct device *dev,
251 int (*fn)(struct attribute_container *,
252 struct device *,
253 struct device *))
254{
255 struct attribute_container *cont;
256
257 mutex_lock(&attribute_container_mutex);
258 list_for_each_entry(cont, &attribute_container_list, node) {
259 struct internal_container *ic;
260 struct klist_iter iter;
261
262 if (!cont->match(cont, dev))
263 continue;
264
265 if (attribute_container_no_classdevs(cont)) {
266 fn(cont, dev, NULL);
267 continue;
268 }
269
270 klist_for_each_entry(ic, &cont->containers, node, &iter) {
271 if (dev == ic->classdev.parent)
272 fn(cont, dev, &ic->classdev);
273 }
274 }
275 mutex_unlock(&attribute_container_mutex);
276}
277
278/**
279 * attribute_container_trigger - trigger a function for each matching container
280 *
281 * @dev: The generic device to activate the trigger for
282 * @fn: the function to trigger
283 *
284 * This routine triggers a function that only needs to know the
285 * matching containers (not the classdev) associated with a device.
286 * It is more lightweight than attribute_container_device_trigger, so
287 * should be used in preference unless the triggering function
288 * actually needs to know the classdev.
289 */
290void
291attribute_container_trigger(struct device *dev,
292 int (*fn)(struct attribute_container *,
293 struct device *))
294{
295 struct attribute_container *cont;
296
297 mutex_lock(&attribute_container_mutex);
298 list_for_each_entry(cont, &attribute_container_list, node) {
299 if (cont->match(cont, dev))
300 fn(cont, dev);
301 }
302 mutex_unlock(&attribute_container_mutex);
303}
304
305/**
306 * attribute_container_add_attrs - add attributes
307 *
308 * @classdev: The class device
309 *
310 * This simply creates all the class device sysfs files from the
311 * attributes listed in the container
312 */
313int
314attribute_container_add_attrs(struct device *classdev)
315{
316 struct attribute_container *cont =
317 attribute_container_classdev_to_container(classdev);
318 struct device_attribute **attrs = cont->attrs;
319 int i, error;
320
321 BUG_ON(attrs && cont->grp);
322
323 if (!attrs && !cont->grp)
324 return 0;
325
326 if (cont->grp)
327 return sysfs_create_group(&classdev->kobj, cont->grp);
328
329 for (i = 0; attrs[i]; i++) {
330 sysfs_attr_init(&attrs[i]->attr);
331 error = device_create_file(classdev, attrs[i]);
332 if (error)
333 return error;
334 }
335
336 return 0;
337}
338
339/**
340 * attribute_container_add_class_device - same function as device_add
341 *
342 * @classdev: the class device to add
343 *
344 * This performs essentially the same function as device_add except for
345 * attribute containers, namely add the classdev to the system and then
346 * create the attribute files
347 */
348int
349attribute_container_add_class_device(struct device *classdev)
350{
351 int error = device_add(classdev);
352
353 if (error)
354 return error;
355 return attribute_container_add_attrs(classdev);
356}
357
358/**
359 * attribute_container_add_class_device_adapter - simple adapter for triggers
360 *
361 * This function is identical to attribute_container_add_class_device except
362 * that it is designed to be called from the triggers
363 */
364int
365attribute_container_add_class_device_adapter(struct attribute_container *cont,
366 struct device *dev,
367 struct device *classdev)
368{
369 return attribute_container_add_class_device(classdev);
370}
371
372/**
373 * attribute_container_remove_attrs - remove any attribute files
374 *
375 * @classdev: The class device to remove the files from
376 *
377 */
378void
379attribute_container_remove_attrs(struct device *classdev)
380{
381 struct attribute_container *cont =
382 attribute_container_classdev_to_container(classdev);
383 struct device_attribute **attrs = cont->attrs;
384 int i;
385
386 if (!attrs && !cont->grp)
387 return;
388
389 if (cont->grp) {
390 sysfs_remove_group(&classdev->kobj, cont->grp);
391 return ;
392 }
393
394 for (i = 0; attrs[i]; i++)
395 device_remove_file(classdev, attrs[i]);
396}
397
398/**
399 * attribute_container_class_device_del - equivalent of class_device_del
400 *
401 * @classdev: the class device
402 *
403 * This function simply removes all the attribute files and then calls
404 * device_del.
405 */
406void
407attribute_container_class_device_del(struct device *classdev)
408{
409 attribute_container_remove_attrs(classdev);
410 device_del(classdev);
411}
412
413/**
414 * attribute_container_find_class_device - find the corresponding class_device
415 *
416 * @cont: the container
417 * @dev: the generic device
418 *
419 * Looks up the device in the container's list of class devices and returns
420 * the corresponding class_device.
421 */
422struct device *
423attribute_container_find_class_device(struct attribute_container *cont,
424 struct device *dev)
425{
426 struct device *cdev = NULL;
427 struct internal_container *ic;
428 struct klist_iter iter;
429
430 klist_for_each_entry(ic, &cont->containers, node, &iter) {
431 if (ic->classdev.parent == dev) {
432 cdev = &ic->classdev;
433 /* FIXME: must exit iterator then break */
434 klist_iter_exit(&iter);
435 break;
436 }
437 }
438
439 return cdev;
440}
441EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
442