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(dev: &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(dev: &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(list: &cont->node);
76 klist_init(k: &cont->containers, get: internal_container_klist_get,
77 put: internal_container_klist_put);
78
79 mutex_lock(&attribute_container_mutex);
80 list_add_tail(new: &cont->node, head: &attribute_container_list);
81 mutex_unlock(lock: &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(lock: &cont->containers.k_lock);
99 if (!list_empty(head: &cont->containers.k_list))
100 goto out;
101 retval = 0;
102 list_del(entry: &cont->node);
103 out:
104 spin_unlock(lock: &cont->containers.k_lock);
105 mutex_unlock(lock: &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(objp: 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(atc: cont))
153 continue;
154
155 if (!cont->match(cont, dev))
156 continue;
157
158 ic = kzalloc(size: 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(dev: &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(dev: &ic->classdev, name: "%s", dev_name(dev));
170 if (fn)
171 fn(cont, dev, &ic->classdev);
172 else
173 attribute_container_add_class_device(classdev: &ic->classdev);
174 klist_add_tail(n: &ic->node, k: &cont->containers);
175 }
176 mutex_unlock(lock: &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(atc: 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(n: &ic->node);
228 if (fn)
229 fn(cont, dev, &ic->classdev);
230 else {
231 attribute_container_remove_attrs(classdev: &ic->classdev);
232 device_unregister(dev: &ic->classdev);
233 }
234 }
235 }
236 mutex_unlock(lock: &attribute_container_mutex);
237}
238
239static int
240do_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(atc: 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(i: &iter);
260 goto fail;
261 }
262 }
263 }
264 return 0;
265
266fail:
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(i: &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 */
296int
297attribute_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 fn: undo, NULL);
334 }
335 }
336
337 mutex_unlock(lock: &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. If you only care about the
350 * container, then use attribute_container_trigger() instead.
351 */
352void
353attribute_container_device_trigger(struct device *dev,
354 int (*fn)(struct attribute_container *,
355 struct device *,
356 struct device *))
357{
358 struct attribute_container *cont;
359
360 mutex_lock(&attribute_container_mutex);
361 list_for_each_entry(cont, &attribute_container_list, node) {
362 struct internal_container *ic;
363 struct klist_iter iter;
364
365 if (!cont->match(cont, dev))
366 continue;
367
368 if (attribute_container_no_classdevs(atc: cont)) {
369 fn(cont, dev, NULL);
370 continue;
371 }
372
373 klist_for_each_entry(ic, &cont->containers, node, &iter) {
374 if (dev == ic->classdev.parent)
375 fn(cont, dev, &ic->classdev);
376 }
377 }
378 mutex_unlock(lock: &attribute_container_mutex);
379}
380
381/**
382 * attribute_container_trigger - trigger a function for each matching container
383 *
384 * @dev: The generic device to activate the trigger for
385 * @fn: the function to trigger
386 *
387 * This routine triggers a function that only needs to know the
388 * matching containers (not the classdev) associated with a device.
389 * It is more lightweight than attribute_container_device_trigger, so
390 * should be used in preference unless the triggering function
391 * actually needs to know the classdev.
392 */
393void
394attribute_container_trigger(struct device *dev,
395 int (*fn)(struct attribute_container *,
396 struct device *))
397{
398 struct attribute_container *cont;
399
400 mutex_lock(&attribute_container_mutex);
401 list_for_each_entry(cont, &attribute_container_list, node) {
402 if (cont->match(cont, dev))
403 fn(cont, dev);
404 }
405 mutex_unlock(lock: &attribute_container_mutex);
406}
407
408/**
409 * attribute_container_add_attrs - add attributes
410 *
411 * @classdev: The class device
412 *
413 * This simply creates all the class device sysfs files from the
414 * attributes listed in the container
415 */
416int
417attribute_container_add_attrs(struct device *classdev)
418{
419 struct attribute_container *cont =
420 attribute_container_classdev_to_container(classdev);
421 struct device_attribute **attrs = cont->attrs;
422 int i, error;
423
424 BUG_ON(attrs && cont->grp);
425
426 if (!attrs && !cont->grp)
427 return 0;
428
429 if (cont->grp)
430 return sysfs_create_group(kobj: &classdev->kobj, grp: cont->grp);
431
432 for (i = 0; attrs[i]; i++) {
433 sysfs_attr_init(&attrs[i]->attr);
434 error = device_create_file(device: classdev, entry: attrs[i]);
435 if (error)
436 return error;
437 }
438
439 return 0;
440}
441
442/**
443 * attribute_container_add_class_device - same function as device_add
444 *
445 * @classdev: the class device to add
446 *
447 * This performs essentially the same function as device_add except for
448 * attribute containers, namely add the classdev to the system and then
449 * create the attribute files
450 */
451int
452attribute_container_add_class_device(struct device *classdev)
453{
454 int error = device_add(dev: classdev);
455
456 if (error)
457 return error;
458 return attribute_container_add_attrs(classdev);
459}
460
461/**
462 * attribute_container_add_class_device_adapter - simple adapter for triggers
463 *
464 * @cont: the container to register.
465 * @dev: the generic device to activate the trigger for
466 * @classdev: the class device to add
467 *
468 * This function is identical to attribute_container_add_class_device except
469 * that it is designed to be called from the triggers
470 */
471int
472attribute_container_add_class_device_adapter(struct attribute_container *cont,
473 struct device *dev,
474 struct device *classdev)
475{
476 return attribute_container_add_class_device(classdev);
477}
478
479/**
480 * attribute_container_remove_attrs - remove any attribute files
481 *
482 * @classdev: The class device to remove the files from
483 *
484 */
485void
486attribute_container_remove_attrs(struct device *classdev)
487{
488 struct attribute_container *cont =
489 attribute_container_classdev_to_container(classdev);
490 struct device_attribute **attrs = cont->attrs;
491 int i;
492
493 if (!attrs && !cont->grp)
494 return;
495
496 if (cont->grp) {
497 sysfs_remove_group(kobj: &classdev->kobj, grp: cont->grp);
498 return ;
499 }
500
501 for (i = 0; attrs[i]; i++)
502 device_remove_file(dev: classdev, attr: attrs[i]);
503}
504
505/**
506 * attribute_container_class_device_del - equivalent of class_device_del
507 *
508 * @classdev: the class device
509 *
510 * This function simply removes all the attribute files and then calls
511 * device_del.
512 */
513void
514attribute_container_class_device_del(struct device *classdev)
515{
516 attribute_container_remove_attrs(classdev);
517 device_del(dev: classdev);
518}
519
520/**
521 * attribute_container_find_class_device - find the corresponding class_device
522 *
523 * @cont: the container
524 * @dev: the generic device
525 *
526 * Looks up the device in the container's list of class devices and returns
527 * the corresponding class_device.
528 */
529struct device *
530attribute_container_find_class_device(struct attribute_container *cont,
531 struct device *dev)
532{
533 struct device *cdev = NULL;
534 struct internal_container *ic;
535 struct klist_iter iter;
536
537 klist_for_each_entry(ic, &cont->containers, node, &iter) {
538 if (ic->classdev.parent == dev) {
539 cdev = &ic->classdev;
540 /* FIXME: must exit iterator then break */
541 klist_iter_exit(i: &iter);
542 break;
543 }
544 }
545
546 return cdev;
547}
548EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
549

source code of linux/drivers/base/attribute_container.c