1/*
2 * attribute_container.c - implementation of a simple container for classes
3 *
4 * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com>
5 *
6 * This file is licensed under GPLv2
7 *
8 * The basic idea here is to enable a device to be attached to an
9 * aritrary numer of classes without having to allocate storage for them.
10 * Instead, the contained classes select the devices they need to attach
11 * to via a matching function.
12 */
13
14#include <linux/attribute_container.h>
15#include <linux/device.h>
16#include <linux/kernel.h>
17#include <linux/slab.h>
18#include <linux/list.h>
19#include <linux/module.h>
20#include <linux/mutex.h>
21
22#include "base.h"
23
24/* This is a private structure used to tie the classdev and the
25 * container .. it should never be visible outside this file */
26struct internal_container {
27	struct klist_node node;
28	struct attribute_container *cont;
29	struct device classdev;
30};
31
32static void internal_container_klist_get(struct klist_node *n)
33{
34	struct internal_container *ic =
35		container_of(n, struct internal_container, node);
36	get_device(&ic->classdev);
37}
38
39static void internal_container_klist_put(struct klist_node *n)
40{
41	struct internal_container *ic =
42		container_of(n, struct internal_container, node);
43	put_device(&ic->classdev);
44}
45
46
47/**
48 * attribute_container_classdev_to_container - given a classdev, return the container
49 *
50 * @classdev: the class device created by attribute_container_add_device.
51 *
52 * Returns the container associated with this classdev.
53 */
54struct attribute_container *
55attribute_container_classdev_to_container(struct device *classdev)
56{
57	struct internal_container *ic =
58		container_of(classdev, struct internal_container, classdev);
59	return ic->cont;
60}
61EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);
62
63static LIST_HEAD(attribute_container_list);
64
65static DEFINE_MUTEX(attribute_container_mutex);
66
67/**
68 * attribute_container_register - register an attribute container
69 *
70 * @cont: The container to register.  This must be allocated by the
71 *        callee and should also be zeroed by it.
72 */
73int
74attribute_container_register(struct attribute_container *cont)
75{
76	INIT_LIST_HEAD(&cont->node);
77	klist_init(&cont->containers, internal_container_klist_get,
78		   internal_container_klist_put);
79
80	mutex_lock(&attribute_container_mutex);
81	list_add_tail(&cont->node, &attribute_container_list);
82	mutex_unlock(&attribute_container_mutex);
83
84	return 0;
85}
86EXPORT_SYMBOL_GPL(attribute_container_register);
87
88/**
89 * attribute_container_unregister - remove a container registration
90 *
91 * @cont: previously registered container to remove
92 */
93int
94attribute_container_unregister(struct attribute_container *cont)
95{
96	int retval = -EBUSY;
97
98	mutex_lock(&attribute_container_mutex);
99	spin_lock(&cont->containers.k_lock);
100	if (!list_empty(&cont->containers.k_list))
101		goto out;
102	retval = 0;
103	list_del(&cont->node);
104 out:
105	spin_unlock(&cont->containers.k_lock);
106	mutex_unlock(&attribute_container_mutex);
107	return retval;
108
109}
110EXPORT_SYMBOL_GPL(attribute_container_unregister);
111
112/* private function used as class release */
113static void attribute_container_release(struct device *classdev)
114{
115	struct internal_container *ic
116		= container_of(classdev, struct internal_container, classdev);
117	struct device *dev = classdev->parent;
118
119	kfree(ic);
120	put_device(dev);
121}
122
123/**
124 * attribute_container_add_device - see if any container is interested in dev
125 *
126 * @dev: device to add attributes to
127 * @fn:	 function to trigger addition of class device.
128 *
129 * This function allocates storage for the class device(s) to be
130 * attached to dev (one for each matching attribute_container).  If no
131 * fn is provided, the code will simply register the class device via
132 * device_add.  If a function is provided, it is expected to add
133 * the class device at the appropriate time.  One of the things that
134 * might be necessary is to allocate and initialise the classdev and
135 * then add it a later time.  To do this, call this routine for
136 * allocation and initialisation and then use
137 * attribute_container_device_trigger() to call device_add() on
138 * it.  Note: after this, the class device contains a reference to dev
139 * which is not relinquished until the release of the classdev.
140 */
141void
142attribute_container_add_device(struct device *dev,
143			       int (*fn)(struct attribute_container *,
144					 struct device *,
145					 struct device *))
146{
147	struct attribute_container *cont;
148
149	mutex_lock(&attribute_container_mutex);
150	list_for_each_entry(cont, &attribute_container_list, node) {
151		struct internal_container *ic;
152
153		if (attribute_container_no_classdevs(cont))
154			continue;
155
156		if (!cont->match(cont, dev))
157			continue;
158
159		ic = kzalloc(sizeof(*ic), GFP_KERNEL);
160		if (!ic) {
161			dev_err(dev, "failed to allocate class container\n");
162			continue;
163		}
164
165		ic->cont = cont;
166		device_initialize(&ic->classdev);
167		ic->classdev.parent = get_device(dev);
168		ic->classdev.class = cont->class;
169		cont->class->dev_release = attribute_container_release;
170		dev_set_name(&ic->classdev, "%s", dev_name(dev));
171		if (fn)
172			fn(cont, dev, &ic->classdev);
173		else
174			attribute_container_add_class_device(&ic->classdev);
175		klist_add_tail(&ic->node, &cont->containers);
176	}
177	mutex_unlock(&attribute_container_mutex);
178}
179
180/* FIXME: can't break out of this unless klist_iter_exit is also
181 * called before doing the break
182 */
183#define klist_for_each_entry(pos, head, member, iter) \
184	for (klist_iter_init(head, iter); (pos = ({ \
185		struct klist_node *n = klist_next(iter); \
186		n ? container_of(n, typeof(*pos), member) : \
187			({ klist_iter_exit(iter) ; NULL; }); \
188	})) != NULL;)
189
190
191/**
192 * attribute_container_remove_device - make device eligible for removal.
193 *
194 * @dev:  The generic device
195 * @fn:	  A function to call to remove the device
196 *
197 * This routine triggers device removal.  If fn is NULL, then it is
198 * simply done via device_unregister (note that if something
199 * still has a reference to the classdev, then the memory occupied
200 * will not be freed until the classdev is released).  If you want a
201 * two phase release: remove from visibility and then delete the
202 * device, then you should use this routine with a fn that calls
203 * device_del() and then use attribute_container_device_trigger()
204 * to do the final put on the classdev.
205 */
206void
207attribute_container_remove_device(struct device *dev,
208				  void (*fn)(struct attribute_container *,
209					     struct device *,
210					     struct device *))
211{
212	struct attribute_container *cont;
213
214	mutex_lock(&attribute_container_mutex);
215	list_for_each_entry(cont, &attribute_container_list, node) {
216		struct internal_container *ic;
217		struct klist_iter iter;
218
219		if (attribute_container_no_classdevs(cont))
220			continue;
221
222		if (!cont->match(cont, dev))
223			continue;
224
225		klist_for_each_entry(ic, &cont->containers, node, &iter) {
226			if (dev != ic->classdev.parent)
227				continue;
228			klist_del(&ic->node);
229			if (fn)
230				fn(cont, dev, &ic->classdev);
231			else {
232				attribute_container_remove_attrs(&ic->classdev);
233				device_unregister(&ic->classdev);
234			}
235		}
236	}
237	mutex_unlock(&attribute_container_mutex);
238}
239
240/**
241 * attribute_container_device_trigger - execute a trigger for each matching classdev
242 *
243 * @dev:  The generic device to run the trigger for
244 * @fn	  the function to execute for each classdev.
245 *
246 * This funcion is for executing a trigger when you need to know both
247 * the container and the classdev.  If you only care about the
248 * container, then use attribute_container_trigger() instead.
249 */
250void
251attribute_container_device_trigger(struct device *dev,
252				   int (*fn)(struct attribute_container *,
253					     struct device *,
254					     struct device *))
255{
256	struct attribute_container *cont;
257
258	mutex_lock(&attribute_container_mutex);
259	list_for_each_entry(cont, &attribute_container_list, node) {
260		struct internal_container *ic;
261		struct klist_iter iter;
262
263		if (!cont->match(cont, dev))
264			continue;
265
266		if (attribute_container_no_classdevs(cont)) {
267			fn(cont, dev, NULL);
268			continue;
269		}
270
271		klist_for_each_entry(ic, &cont->containers, node, &iter) {
272			if (dev == ic->classdev.parent)
273				fn(cont, dev, &ic->classdev);
274		}
275	}
276	mutex_unlock(&attribute_container_mutex);
277}
278
279/**
280 * attribute_container_trigger - trigger a function for each matching container
281 *
282 * @dev:  The generic device to activate the trigger for
283 * @fn:	  the function to trigger
284 *
285 * This routine triggers a function that only needs to know the
286 * matching containers (not the classdev) associated with a device.
287 * It is more lightweight than attribute_container_device_trigger, so
288 * should be used in preference unless the triggering function
289 * actually needs to know the classdev.
290 */
291void
292attribute_container_trigger(struct device *dev,
293			    int (*fn)(struct attribute_container *,
294				      struct device *))
295{
296	struct attribute_container *cont;
297
298	mutex_lock(&attribute_container_mutex);
299	list_for_each_entry(cont, &attribute_container_list, node) {
300		if (cont->match(cont, dev))
301			fn(cont, dev);
302	}
303	mutex_unlock(&attribute_container_mutex);
304}
305
306/**
307 * attribute_container_add_attrs - add attributes
308 *
309 * @classdev: The class device
310 *
311 * This simply creates all the class device sysfs files from the
312 * attributes listed in the container
313 */
314int
315attribute_container_add_attrs(struct device *classdev)
316{
317	struct attribute_container *cont =
318		attribute_container_classdev_to_container(classdev);
319	struct device_attribute **attrs = cont->attrs;
320	int i, error;
321
322	BUG_ON(attrs && cont->grp);
323
324	if (!attrs && !cont->grp)
325		return 0;
326
327	if (cont->grp)
328		return sysfs_create_group(&classdev->kobj, cont->grp);
329
330	for (i = 0; attrs[i]; i++) {
331		sysfs_attr_init(&attrs[i]->attr);
332		error = device_create_file(classdev, attrs[i]);
333		if (error)
334			return error;
335	}
336
337	return 0;
338}
339
340/**
341 * attribute_container_add_class_device - same function as device_add
342 *
343 * @classdev:	the class device to add
344 *
345 * This performs essentially the same function as device_add except for
346 * attribute containers, namely add the classdev to the system and then
347 * create the attribute files
348 */
349int
350attribute_container_add_class_device(struct device *classdev)
351{
352	int error = device_add(classdev);
353
354	if (error)
355		return error;
356	return attribute_container_add_attrs(classdev);
357}
358
359/**
360 * attribute_container_add_class_device_adapter - simple adapter for triggers
361 *
362 * This function is identical to attribute_container_add_class_device except
363 * that it is designed to be called from the triggers
364 */
365int
366attribute_container_add_class_device_adapter(struct attribute_container *cont,
367					     struct device *dev,
368					     struct device *classdev)
369{
370	return attribute_container_add_class_device(classdev);
371}
372
373/**
374 * attribute_container_remove_attrs - remove any attribute files
375 *
376 * @classdev: The class device to remove the files from
377 *
378 */
379void
380attribute_container_remove_attrs(struct device *classdev)
381{
382	struct attribute_container *cont =
383		attribute_container_classdev_to_container(classdev);
384	struct device_attribute **attrs = cont->attrs;
385	int i;
386
387	if (!attrs && !cont->grp)
388		return;
389
390	if (cont->grp) {
391		sysfs_remove_group(&classdev->kobj, cont->grp);
392		return ;
393	}
394
395	for (i = 0; attrs[i]; i++)
396		device_remove_file(classdev, attrs[i]);
397}
398
399/**
400 * attribute_container_class_device_del - equivalent of class_device_del
401 *
402 * @classdev: the class device
403 *
404 * This function simply removes all the attribute files and then calls
405 * device_del.
406 */
407void
408attribute_container_class_device_del(struct device *classdev)
409{
410	attribute_container_remove_attrs(classdev);
411	device_del(classdev);
412}
413
414/**
415 * attribute_container_find_class_device - find the corresponding class_device
416 *
417 * @cont:	the container
418 * @dev:	the generic device
419 *
420 * Looks up the device in the container's list of class devices and returns
421 * the corresponding class_device.
422 */
423struct device *
424attribute_container_find_class_device(struct attribute_container *cont,
425				      struct device *dev)
426{
427	struct device *cdev = NULL;
428	struct internal_container *ic;
429	struct klist_iter iter;
430
431	klist_for_each_entry(ic, &cont->containers, node, &iter) {
432		if (ic->classdev.parent == dev) {
433			cdev = &ic->classdev;
434			/* FIXME: must exit iterator then break */
435			klist_iter_exit(&iter);
436			break;
437		}
438	}
439
440	return cdev;
441}
442EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
443