aboutsummaryrefslogtreecommitdiff
path: root/drivers/base/attribute_container.c
blob: b84ca8f13f9e1361d51b82a90f29cc525fb9c33e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
/*
 * attribute_container.c - implementation of a simple container for classes
 *
 * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com>
 *
 * This file is licensed under GPLv2
 *
 * The basic idea here is to enable a device to be attached to an
 * aritrary numer of classes without having to allocate storage for them.
 * Instead, the contained classes select the devices they need to attach
 * to via a matching function.
 */

#include <linux/attribute_container.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>

#include "base.h"

/* This is a private structure used to tie the classdev and the
 * container .. it should never be visible outside this file */
struct internal_container {
	struct klist_node node;
	struct attribute_container *cont;
	struct device classdev;
};

static void internal_container_klist_get(struct klist_node *n)
{
	struct internal_container *ic =
		container_of(n, struct internal_container, node);
	get_device(&ic->classdev);
}

static void internal_container_klist_put(struct klist_node *n)
{
	struct internal_container *ic =
		container_of(n, struct internal_container, node);
	put_device(&ic->classdev);
}


/**
 * attribute_container_classdev_to_container - given a classdev, return the container
 *
 * @classdev: the class device created by attribute_container_add_device.
 *
 * Returns the container associated with this classdev.
 */
struct attribute_container *
attribute_container_classdev_to_container(struct device *classdev)
{
	struct internal_container *ic =
		container_of(classdev, struct internal_container, classdev);
	return ic->cont;
}
EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);

static LIST_HEAD(attribute_container_list);

static DEFINE_MUTEX(attribute_container_mutex);

/**
 * attribute_container_register - register an attribute container
 *
 * @cont: The container to register.  This must be allocated by the
 *        callee and should also be zeroed by it.
 */
int
attribute_container_register(struct attribute_container *cont)
{
	INIT_LIST_HEAD(&cont->node);
	klist_init(&cont->containers,internal_container_klist_get,
		   internal_container_klist_put);
		
	mutex_lock(&attribute_container_mutex);
	list_add_tail(&cont->node, &attribute_container_list);
	mutex_unlock(&attribute_container_mutex);

	return 0;
}
EXPORT_SYMBOL_GPL(attribute_container_register);

/**
 * attribute_container_unregister - remove a container registration
 *
 * @cont: previously registered container to remove
 */
int
attribute_container_unregister(struct attribute_container *cont)
{
	int retval = -EBUSY;
	mutex_lock(&attribute_container_mutex);
	spin_lock(&cont->containers.k_lock);
	if (!list_empty(&cont->containers.k_list))
		goto out;
	retval = 0;
	list_del(&cont->node);
 out:
	spin_unlock(&cont->containers.k_lock);
	mutex_unlock(&attribute_container_mutex);
	return retval;
		
}
EXPORT_SYMBOL_GPL(attribute_container_unregister);

/* private function used as class release */
static void attribute_container_release(struct device *classdev)
{
	struct internal_container *ic 
		= container_of(classdev, struct internal_container, classdev);
	struct device *dev = classdev->parent;

	kfree(ic);
	put_device(dev);
}

/**
 * attribute_container_add_device - see if any container is interested in dev
 *
 * @dev: device to add attributes to
 * @fn:	 function to trigger addition of class device.
 *
 * This function allocates storage for the class device(s) to be
 * attached to dev (one for each matching attribute_container).  If no
 * fn is provided, the code will simply register the class device via
 * device_add.  If a function is provided, it is expected to add
 * the class device at the appropriate time.  One of the things that
 * might be necessary is to allocate and initialise the classdev and
 * then add it a later time.  To do this, call this routine for
 * allocation and initialisation and then use
 * attribute_container_device_trigger() to call device_add() on
 * it.  Note: after this, the class device contains a reference to dev
 * which is not relinquished until the release of the classdev.
 */
void
attribute_container_add_device(struct device *dev,
			       int (*fn)(struct attribute_container *,
					 struct device *,
					 struct device *))
{
	struct attribute_container *cont;

	mutex_lock(&attribute_container_mutex);
	list_for_each_entry(cont, &attribute_container_list, node) {
		struct internal_container *ic;

		if (attribute_container_no_classdevs(cont))
			continue;

		if (!cont->match(cont, dev))
			continue;

		ic = kzalloc(sizeof(*ic), GFP_KERNEL);
		if (!ic) {
			dev_err(dev, "failed to allocate class container\n");
			continue;
		}

		ic->cont = cont;
		device_initialize(&ic->classdev);
		ic->classdev.parent = get_device(dev);
		ic->classdev.class = cont->class;
		cont->class->dev_release = attribute_container_release;
		dev_set_name(&ic->classdev, "%s", dev_name(dev));
		if (fn)
			fn(cont, dev, &ic->classdev);
		else
			attribute_container_add_class_device(&ic->classdev);
		klist_add_tail(&ic->node, &cont->containers);
	}
	mutex_unlock(&attribute_container_mutex);
}

/* FIXME: can't break out of this unless klist_iter_exit is also
 * called before doing the break
 */
#define klist_for_each_entry(pos, head, member, iter) \
	for (klist_iter_init(head, iter); (pos = ({ \
		struct klist_node *n = klist_next(iter); \
		n ? container_of(n, typeof(*pos), member) : \
			({ klist_iter_exit(iter) ; NULL; }); \
	}) ) != NULL; )
			

/**
 * attribute_container_remove_device - make device eligible for removal.
 *
 * @dev:  The generic device
 * @fn:	  A function to call to remove the device
 *
 * This routine triggers device removal.  If fn is NULL, then it is
 * simply done via device_unregister (note that if something
 * still has a reference to the classdev, then the memory occupied
 * will not be freed until the classdev is released).  If you want a
 * two phase release: remove from visibility and then delete the
 * device, then you should use this routine with a fn that calls
 * device_del() and then use attribute_container_device_trigger()
 * to do the final put on the classdev.
 */
void
attribute_container_remove_device(struct device *dev,
				  void (*fn)(struct attribute_container *,
					     struct device *,
					     struct device *))
{
	struct attribute_container *cont;

	mutex_lock(&attribute_container_mutex);
	list_for_each_entry(cont, &attribute_container_list, node) {
		struct internal_container *ic;
		struct klist_iter iter;

		if (attribute_container_no_classdevs(cont))
			continue;

		if (!cont->match(cont, dev))
			continue;

		klist_for_each_entry(ic, &cont->containers, node, &iter) {
			if (dev != ic->classdev.parent)
				continue;
			klist_del(&ic->node);
			if (fn)
				fn(cont, dev, &ic->classdev);
			else {
				attribute_container_remove_attrs(&ic->classdev);
				device_unregister(&ic->classdev);
			}
		}
	}
	mutex_unlock(&attribute_container_mutex);
}

/**
 * attribute_container_device_trigger - execute a trigger for each matching classdev
 *
 * @dev:  The generic device to run the trigger for
 * @fn	  the function to execute for each classdev.
 *
 * This funcion is for executing a trigger when you need to know both
 * the container and the classdev.  If you only care about the
 * container, then use attribute_container_trigger() instead.
 */
void
attribute_container_device_trigger(struct device *dev, 
				   int (*fn)(struct attribute_container *,
					     struct device *,
					     struct device *))
{
	struct attribute_container *cont;

	mutex_lock(&attribute_container_mutex);
	list_for_each_entry(cont, &attribute_container_list, node) {
		struct internal_container *ic;
		struct klist_iter iter;

		if (!cont->match(cont, dev))
			continue;

		if (attribute_container_no_classdevs(cont)) {
			fn(cont, dev, NULL);
			continue;
		}

		klist_for_each_entry(ic, &cont->containers, node, &iter) {
			if (dev == ic->classdev.parent)
				fn(cont, dev, &ic->classdev);
		}
	}
	mutex_unlock(&attribute_container_mutex);
}

/**
 * attribute_container_trigger - trigger a function for each matching container
 *
 * @dev:  The generic device to activate the trigger for
 * @fn:	  the function to trigger
 *
 * This routine triggers a function that only needs to know the
 * matching containers (not the classdev) associated with a device.
 * It is more lightweight than attribute_container_device_trigger, so
 * should be used in preference unless the triggering function
 * actually needs to know the classdev.
 */
void
attribute_container_trigger(struct device *dev,
			    int (*fn)(struct attribute_container *,
				      struct device *))
{
	struct attribute_container *cont;

	mutex_lock(&attribute_container_mutex);
	list_for_each_entry(cont, &attribute_container_list, node) {
		if (cont->match(cont, dev))
			fn(cont, dev);
	}
	mutex_unlock(&attribute_container_mutex);
}

/**
 * attribute_container_add_attrs - add attributes
 *
 * @classdev: The class device
 *
 * This simply creates all the class device sysfs files from the
 * attributes listed in the container
 */
int
attribute_container_add_attrs(struct device *classdev)
{
	struct attribute_container *cont =
		attribute_container_classdev_to_container(classdev);
	struct device_attribute **attrs = cont->attrs;
	int i, error;

	BUG_ON(attrs && cont->grp);

	if (!attrs && !cont->grp)
		return 0;

	if (cont->grp)
		return sysfs_create_group(&classdev->kobj, cont->grp);

	for (i = 0; attrs[i]; i++) {
		sysfs_attr_init(&attrs[i]->attr);
		error = device_create_file(classdev, attrs[i]);
		if (error)
			return error;
	}

	return 0;
}

/**
 * attribute_container_add_class_device - same function as device_add
 *
 * @classdev:	the class device to add
 *
 * This performs essentially the same function as device_add except for
 * attribute containers, namely add the classdev to the system and then
 * create the attribute files
 */
int
attribute_container_add_class_device(struct device *classdev)
{
	int error = device_add(classdev);
	if (error)
		return error;
	return attribute_container_add_attrs(classdev);
}

/**
 * attribute_container_add_class_device_adapter - simple adapter for triggers
 *
 * This function is identical to attribute_container_add_class_device except
 * that it is designed to be called from the triggers
 */
int
attribute_container_add_class_device_adapter(struct attribute_container *cont,
					     struct device *dev,
					     struct device *classdev)
{
	return attribute_container_add_class_device(classdev);
}

/**
 * attribute_container_remove_attrs - remove any attribute files
 *
 * @classdev: The class device to remove the files from
 *
 */
void
attribute_container_remove_attrs(struct device *classdev)
{
	struct attribute_container *cont =
		attribute_container_classdev_to_container(classdev);
	struct device_attribute **attrs = cont->attrs;
	int i;

	if (!attrs && !cont->grp)
		return;

	if (cont->grp) {
		sysfs_remove_group(&classdev->kobj, cont->grp);
		return ;
	}

	for (i = 0; attrs[i]; i++)
		device_remove_file(classdev, attrs[i]);
}

/**
 * attribute_container_class_device_del - equivalent of class_device_del
 *
 * @classdev: the class device
 *
 * This function simply removes all the attribute files and then calls
 * device_del.
 */
void
attribute_container_class_device_del(struct device *classdev)
{
	attribute_container_remove_attrs(classdev);
	device_del(classdev);
}

/**
 * attribute_container_find_class_device - find the corresponding class_device
 *
 * @cont:	the container
 * @dev:	the generic device
 *
 * Looks up the device in the container's list of class devices and returns
 * the corresponding class_device.
 */
struct device *
attribute_container_find_class_device(struct attribute_container *cont,
				      struct device *dev)
{
	struct device *cdev = NULL;
	struct internal_container *ic;
	struct klist_iter iter;

	klist_for_each_entry(ic, &cont->containers, node, &iter) {
		if (ic->classdev.parent == dev) {
			cdev = &ic->classdev;
			/* FIXME: must exit iterator then break */
			klist_iter_exit(&iter);
			break;
		}
	}

	return cdev;
}
EXPORT_SYMBOL_GPL(attribute_container_find_class_device);