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 */
25 struct internal_container {
26 struct klist_node node;
27 struct attribute_container *cont;
28 struct device classdev;
29 };
30
internal_container_klist_get(struct klist_node * n)31 static 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
internal_container_klist_put(struct klist_node * n)38 static 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 */
53 struct attribute_container *
attribute_container_classdev_to_container(struct device * classdev)54 attribute_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 }
60 EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);
61
62 static LIST_HEAD(attribute_container_list);
63
64 static 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 */
72 int
attribute_container_register(struct attribute_container * cont)73 attribute_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 }
85 EXPORT_SYMBOL_GPL(attribute_container_register);
86
87 /**
88 * attribute_container_unregister - remove a container registration
89 *
90 * @cont: previously registered container to remove
91 */
92 int
attribute_container_unregister(struct attribute_container * cont)93 attribute_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 }
109 EXPORT_SYMBOL_GPL(attribute_container_unregister);
110
111 /* private function used as class release */
attribute_container_release(struct device * classdev)112 static 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 */
140 void
attribute_container_add_device(struct device * dev,int (* fn)(struct attribute_container *,struct device *,struct device *))141 attribute_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 */
205 void
attribute_container_remove_device(struct device * dev,void (* fn)(struct attribute_container *,struct device *,struct device *))206 attribute_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 static int
do_attribute_container_device_trigger_safe(struct device * dev,struct attribute_container * cont,int (* fn)(struct attribute_container *,struct device *,struct device *),int (* undo)(struct attribute_container *,struct device *,struct device *))240 do_attribute_container_device_trigger_safe(struct device *dev,
241 struct attribute_container *cont,
242 int (*fn)(struct attribute_container *,
243 struct device *, struct device *),
244 int (*undo)(struct attribute_container *,
245 struct device *, struct device *))
246 {
247 int ret;
248 struct internal_container *ic, *failed;
249 struct klist_iter iter;
250
251 if (attribute_container_no_classdevs(cont))
252 return fn(cont, dev, NULL);
253
254 klist_for_each_entry(ic, &cont->containers, node, &iter) {
255 if (dev == ic->classdev.parent) {
256 ret = fn(cont, dev, &ic->classdev);
257 if (ret) {
258 failed = ic;
259 klist_iter_exit(&iter);
260 goto fail;
261 }
262 }
263 }
264 return 0;
265
266 fail:
267 if (!undo)
268 return ret;
269
270 /* Attempt to undo the work partially done. */
271 klist_for_each_entry(ic, &cont->containers, node, &iter) {
272 if (ic == failed) {
273 klist_iter_exit(&iter);
274 break;
275 }
276 if (dev == ic->classdev.parent)
277 undo(cont, dev, &ic->classdev);
278 }
279 return ret;
280 }
281
282 /**
283 * attribute_container_device_trigger_safe - execute a trigger for each
284 * matching classdev or fail all of them.
285 *
286 * @dev: The generic device to run the trigger for
287 * @fn: the function to execute for each classdev.
288 * @undo: A function to undo the work previously done in case of error
289 *
290 * This function is a safe version of
291 * attribute_container_device_trigger. It stops on the first error and
292 * undo the partial work that has been done, on previous classdev. It
293 * is guaranteed that either they all succeeded, or none of them
294 * succeeded.
295 */
296 int
attribute_container_device_trigger_safe(struct device * dev,int (* fn)(struct attribute_container *,struct device *,struct device *),int (* undo)(struct attribute_container *,struct device *,struct device *))297 attribute_container_device_trigger_safe(struct device *dev,
298 int (*fn)(struct attribute_container *,
299 struct device *,
300 struct device *),
301 int (*undo)(struct attribute_container *,
302 struct device *,
303 struct device *))
304 {
305 struct attribute_container *cont, *failed = NULL;
306 int ret = 0;
307
308 mutex_lock(&attribute_container_mutex);
309
310 list_for_each_entry(cont, &attribute_container_list, node) {
311
312 if (!cont->match(cont, dev))
313 continue;
314
315 ret = do_attribute_container_device_trigger_safe(dev, cont,
316 fn, undo);
317 if (ret) {
318 failed = cont;
319 break;
320 }
321 }
322
323 if (ret && !WARN_ON(!undo)) {
324 list_for_each_entry(cont, &attribute_container_list, node) {
325
326 if (failed == cont)
327 break;
328
329 if (!cont->match(cont, dev))
330 continue;
331
332 do_attribute_container_device_trigger_safe(dev, cont,
333 undo, NULL);
334 }
335 }
336
337 mutex_unlock(&attribute_container_mutex);
338 return ret;
339
340 }
341
342 /**
343 * attribute_container_device_trigger - execute a trigger for each matching classdev
344 *
345 * @dev: The generic device to run the trigger for
346 * @fn: the function to execute for each classdev.
347 *
348 * This function is for executing a trigger when you need to know both
349 * the container and the classdev.
350 */
351 void
attribute_container_device_trigger(struct device * dev,int (* fn)(struct attribute_container *,struct device *,struct device *))352 attribute_container_device_trigger(struct device *dev,
353 int (*fn)(struct attribute_container *,
354 struct device *,
355 struct device *))
356 {
357 struct attribute_container *cont;
358
359 mutex_lock(&attribute_container_mutex);
360 list_for_each_entry(cont, &attribute_container_list, node) {
361 struct internal_container *ic;
362 struct klist_iter iter;
363
364 if (!cont->match(cont, dev))
365 continue;
366
367 if (attribute_container_no_classdevs(cont)) {
368 fn(cont, dev, NULL);
369 continue;
370 }
371
372 klist_for_each_entry(ic, &cont->containers, node, &iter) {
373 if (dev == ic->classdev.parent)
374 fn(cont, dev, &ic->classdev);
375 }
376 }
377 mutex_unlock(&attribute_container_mutex);
378 }
379
380 /**
381 * attribute_container_add_attrs - add attributes
382 *
383 * @classdev: The class device
384 *
385 * This simply creates all the class device sysfs files from the
386 * attributes listed in the container
387 */
388 int
attribute_container_add_attrs(struct device * classdev)389 attribute_container_add_attrs(struct device *classdev)
390 {
391 struct attribute_container *cont =
392 attribute_container_classdev_to_container(classdev);
393 struct device_attribute **attrs = cont->attrs;
394 int i, error;
395
396 BUG_ON(attrs && cont->grp);
397
398 if (!attrs && !cont->grp)
399 return 0;
400
401 if (cont->grp)
402 return sysfs_create_group(&classdev->kobj, cont->grp);
403
404 for (i = 0; attrs[i]; i++) {
405 sysfs_attr_init(&attrs[i]->attr);
406 error = device_create_file(classdev, attrs[i]);
407 if (error)
408 return error;
409 }
410
411 return 0;
412 }
413
414 /**
415 * attribute_container_add_class_device - same function as device_add
416 *
417 * @classdev: the class device to add
418 *
419 * This performs essentially the same function as device_add except for
420 * attribute containers, namely add the classdev to the system and then
421 * create the attribute files
422 */
423 int
attribute_container_add_class_device(struct device * classdev)424 attribute_container_add_class_device(struct device *classdev)
425 {
426 int error = device_add(classdev);
427
428 if (error)
429 return error;
430 return attribute_container_add_attrs(classdev);
431 }
432
433 /**
434 * attribute_container_remove_attrs - remove any attribute files
435 *
436 * @classdev: The class device to remove the files from
437 *
438 */
439 void
attribute_container_remove_attrs(struct device * classdev)440 attribute_container_remove_attrs(struct device *classdev)
441 {
442 struct attribute_container *cont =
443 attribute_container_classdev_to_container(classdev);
444 struct device_attribute **attrs = cont->attrs;
445 int i;
446
447 if (!attrs && !cont->grp)
448 return;
449
450 if (cont->grp) {
451 sysfs_remove_group(&classdev->kobj, cont->grp);
452 return ;
453 }
454
455 for (i = 0; attrs[i]; i++)
456 device_remove_file(classdev, attrs[i]);
457 }
458
459 /**
460 * attribute_container_class_device_del - equivalent of class_device_del
461 *
462 * @classdev: the class device
463 *
464 * This function simply removes all the attribute files and then calls
465 * device_del.
466 */
467 void
attribute_container_class_device_del(struct device * classdev)468 attribute_container_class_device_del(struct device *classdev)
469 {
470 attribute_container_remove_attrs(classdev);
471 device_del(classdev);
472 }
473
474 /**
475 * attribute_container_find_class_device - find the corresponding class_device
476 *
477 * @cont: the container
478 * @dev: the generic device
479 *
480 * Looks up the device in the container's list of class devices and returns
481 * the corresponding class_device.
482 */
483 struct device *
attribute_container_find_class_device(struct attribute_container * cont,struct device * dev)484 attribute_container_find_class_device(struct attribute_container *cont,
485 struct device *dev)
486 {
487 struct device *cdev = NULL;
488 struct internal_container *ic;
489 struct klist_iter iter;
490
491 klist_for_each_entry(ic, &cont->containers, node, &iter) {
492 if (ic->classdev.parent == dev) {
493 cdev = &ic->classdev;
494 /* FIXME: must exit iterator then break */
495 klist_iter_exit(&iter);
496 break;
497 }
498 }
499
500 return cdev;
501 }
502 EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
503