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/init.h>
16#include <linux/device.h>
17#include <linux/kernel.h>
18#include <linux/slab.h>
19#include <linux/list.h>
20#include <linux/module.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 class_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	class_device_get(&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	class_device_put(&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 class_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 struct 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	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 class_device *classdev)
113{
114	struct internal_container *ic
115		= container_of(classdev, struct internal_container, classdev);
116	struct device *dev = classdev->dev;
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 * class_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 class_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 class_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_printk(KERN_ERR, dev, "failed to allocate class container\n");
161			continue;
162		}
163
164		ic->cont = cont;
165		class_device_initialize(&ic->classdev);
166		ic->classdev.dev = get_device(dev);
167		ic->classdev.class = cont->class;
168		cont->class->release = attribute_container_release;
169		strcpy(ic->classdev.class_id, dev->bus_id);
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#define klist_for_each_entry(pos, head, member, iter) \
180	for (klist_iter_init(head, iter); (pos = ({ \
181		struct klist_node *n = klist_next(iter); \
182		n ? container_of(n, typeof(*pos), member) : \
183			({ klist_iter_exit(iter) ; NULL; }); \
184	}) ) != NULL; )
185
186
187/**
188 * attribute_container_remove_device - make device eligible for removal.
189 *
190 * @dev:  The generic device
191 * @fn:	  A function to call to remove the device
192 *
193 * This routine triggers device removal.  If fn is NULL, then it is
194 * simply done via class_device_unregister (note that if something
195 * still has a reference to the classdev, then the memory occupied
196 * will not be freed until the classdev is released).  If you want a
197 * two phase release: remove from visibility and then delete the
198 * device, then you should use this routine with a fn that calls
199 * class_device_del() and then use
200 * attribute_container_device_trigger() to do the final put on the
201 * classdev.
202 */
203void
204attribute_container_remove_device(struct device *dev,
205				  void (*fn)(struct attribute_container *,
206					     struct device *,
207					     struct class_device *))
208{
209	struct attribute_container *cont;
210
211	mutex_lock(&attribute_container_mutex);
212	list_for_each_entry(cont, &attribute_container_list, node) {
213		struct internal_container *ic;
214		struct klist_iter iter;
215
216		if (attribute_container_no_classdevs(cont))
217			continue;
218
219		if (!cont->match(cont, dev))
220			continue;
221
222		klist_for_each_entry(ic, &cont->containers, node, &iter) {
223			if (dev != ic->classdev.dev)
224				continue;
225			klist_del(&ic->node);
226			if (fn)
227				fn(cont, dev, &ic->classdev);
228			else {
229				attribute_container_remove_attrs(&ic->classdev);
230				class_device_unregister(&ic->classdev);
231			}
232		}
233	}
234	mutex_unlock(&attribute_container_mutex);
235}
236
237/**
238 * attribute_container_device_trigger - execute a trigger for each matching classdev
239 *
240 * @dev:  The generic device to run the trigger for
241 * @fn	  the function to execute for each classdev.
242 *
243 * This funcion is for executing a trigger when you need to know both
244 * the container and the classdev.  If you only care about the
245 * container, then use attribute_container_trigger() instead.
246 */
247void
248attribute_container_device_trigger(struct device *dev,
249				   int (*fn)(struct attribute_container *,
250					     struct device *,
251					     struct class_device *))
252{
253	struct attribute_container *cont;
254
255	mutex_lock(&attribute_container_mutex);
256	list_for_each_entry(cont, &attribute_container_list, node) {
257		struct internal_container *ic;
258		struct klist_iter iter;
259
260		if (!cont->match(cont, dev))
261			continue;
262
263		if (attribute_container_no_classdevs(cont)) {
264			fn(cont, dev, NULL);
265			continue;
266		}
267
268		klist_for_each_entry(ic, &cont->containers, node, &iter) {
269			if (dev == ic->classdev.dev)
270				fn(cont, dev, &ic->classdev);
271		}
272	}
273	mutex_unlock(&attribute_container_mutex);
274}
275
276/**
277 * attribute_container_trigger - trigger a function for each matching container
278 *
279 * @dev:  The generic device to activate the trigger for
280 * @fn:	  the function to trigger
281 *
282 * This routine triggers a function that only needs to know the
283 * matching containers (not the classdev) associated with a device.
284 * It is more lightweight than attribute_container_device_trigger, so
285 * should be used in preference unless the triggering function
286 * actually needs to know the classdev.
287 */
288void
289attribute_container_trigger(struct device *dev,
290			    int (*fn)(struct attribute_container *,
291				      struct device *))
292{
293	struct attribute_container *cont;
294
295	mutex_lock(&attribute_container_mutex);
296	list_for_each_entry(cont, &attribute_container_list, node) {
297		if (cont->match(cont, dev))
298			fn(cont, dev);
299	}
300	mutex_unlock(&attribute_container_mutex);
301}
302
303/**
304 * attribute_container_add_attrs - add attributes
305 *
306 * @classdev: The class device
307 *
308 * This simply creates all the class device sysfs files from the
309 * attributes listed in the container
310 */
311int
312attribute_container_add_attrs(struct class_device *classdev)
313{
314	struct attribute_container *cont =
315		attribute_container_classdev_to_container(classdev);
316	struct class_device_attribute **attrs =	cont->attrs;
317	int i, error;
318
319	if (!attrs)
320		return 0;
321
322	for (i = 0; attrs[i]; i++) {
323		error = class_device_create_file(classdev, attrs[i]);
324		if (error)
325			return error;
326	}
327
328	return 0;
329}
330
331/**
332 * attribute_container_add_class_device - same function as class_device_add
333 *
334 * @classdev:	the class device to add
335 *
336 * This performs essentially the same function as class_device_add except for
337 * attribute containers, namely add the classdev to the system and then
338 * create the attribute files
339 */
340int
341attribute_container_add_class_device(struct class_device *classdev)
342{
343	int error = class_device_add(classdev);
344	if (error)
345		return error;
346	return attribute_container_add_attrs(classdev);
347}
348
349/**
350 * attribute_container_add_class_device_adapter - simple adapter for triggers
351 *
352 * This function is identical to attribute_container_add_class_device except
353 * that it is designed to be called from the triggers
354 */
355int
356attribute_container_add_class_device_adapter(struct attribute_container *cont,
357					     struct device *dev,
358					     struct class_device *classdev)
359{
360	return attribute_container_add_class_device(classdev);
361}
362
363/**
364 * attribute_container_remove_attrs - remove any attribute files
365 *
366 * @classdev: The class device to remove the files from
367 *
368 */
369void
370attribute_container_remove_attrs(struct class_device *classdev)
371{
372	struct attribute_container *cont =
373		attribute_container_classdev_to_container(classdev);
374	struct class_device_attribute **attrs =	cont->attrs;
375	int i;
376
377	if (!attrs)
378		return;
379
380	for (i = 0; attrs[i]; i++)
381		class_device_remove_file(classdev, attrs[i]);
382}
383
384/**
385 * attribute_container_class_device_del - equivalent of class_device_del
386 *
387 * @classdev: the class device
388 *
389 * This function simply removes all the attribute files and then calls
390 * class_device_del.
391 */
392void
393attribute_container_class_device_del(struct class_device *classdev)
394{
395	attribute_container_remove_attrs(classdev);
396	class_device_del(classdev);
397}
398
399/**
400 * attribute_container_find_class_device - find the corresponding class_device
401 *
402 * @cont:	the container
403 * @dev:	the generic device
404 *
405 * Looks up the device in the container's list of class devices and returns
406 * the corresponding class_device.
407 */
408struct class_device *
409attribute_container_find_class_device(struct attribute_container *cont,
410				      struct device *dev)
411{
412	struct class_device *cdev = NULL;
413	struct internal_container *ic;
414	struct klist_iter iter;
415
416	klist_for_each_entry(ic, &cont->containers, node, &iter) {
417		if (ic->classdev.dev == dev) {
418			cdev = &ic->classdev;
419			klist_iter_exit(&iter);
420			break;
421		}
422	}
423
424	return cdev;
425}
426EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
427
428int __init
429attribute_container_init(void)
430{
431	INIT_LIST_HEAD(&attribute_container_list);
432	return 0;
433}
434