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
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(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
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(&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								   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.  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(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(&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(&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(&classdev->kobj, cont->grp);
431
432	for (i = 0; attrs[i]; i++) {
433		sysfs_attr_init(&attrs[i]->attr);
434		error = device_create_file(classdev, 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(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(&classdev->kobj, cont->grp);
498		return ;
499	}
500
501	for (i = 0; attrs[i]; i++)
502		device_remove_file(classdev, 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(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(&iter);
542			break;
543		}
544	}
545
546	return cdev;
547}
548EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
549