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 #include <linux/mutex.h>
22
23 #include "base.h"
24
25 /* This is a private structure used to tie the classdev and the
26 * container .. it should never be visible outside this file */
27 struct internal_container {
28 struct klist_node node;
29 struct attribute_container *cont;
30 struct class_device classdev;
31 };
32
33 static void internal_container_klist_get(struct klist_node *n)
34 {
35 struct internal_container *ic =
36 container_of(n, struct internal_container, node);
37 class_device_get(&ic->classdev);
38 }
39
40 static void internal_container_klist_put(struct klist_node *n)
41 {
42 struct internal_container *ic =
43 container_of(n, struct internal_container, node);
44 class_device_put(&ic->classdev);
45 }
46
47
48 /**
49 * attribute_container_classdev_to_container - given a classdev, return the container
50 *
51 * @classdev: the class device created by attribute_container_add_device.
52 *
53 * Returns the container associated with this classdev.
54 */
55 struct attribute_container *
56 attribute_container_classdev_to_container(struct class_device *classdev)
57 {
58 struct internal_container *ic =
59 container_of(classdev, struct internal_container, classdev);
60 return ic->cont;
61 }
62 EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);
63
64 static LIST_HEAD(attribute_container_list);
65
66 static DEFINE_MUTEX(attribute_container_mutex);
67
68 /**
69 * attribute_container_register - register an attribute container
70 *
71 * @cont: The container to register. This must be allocated by the
72 * callee and should also be zeroed by it.
73 */
74 int
75 attribute_container_register(struct attribute_container *cont)
76 {
77 INIT_LIST_HEAD(&cont->node);
78 klist_init(&cont->containers,internal_container_klist_get,
79 internal_container_klist_put);
80
81 mutex_lock(&attribute_container_mutex);
82 list_add_tail(&cont->node, &attribute_container_list);
83 mutex_unlock(&attribute_container_mutex);
84
85 return 0;
86 }
87 EXPORT_SYMBOL_GPL(attribute_container_register);
88
89 /**
90 * attribute_container_unregister - remove a container registration
91 *
92 * @cont: previously registered container to remove
93 */
94 int
95 attribute_container_unregister(struct attribute_container *cont)
96 {
97 int retval = -EBUSY;
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 }
110 EXPORT_SYMBOL_GPL(attribute_container_unregister);
111
112 /* private function used as class release */
113 static void attribute_container_release(struct class_device *classdev)
114 {
115 struct internal_container *ic
116 = container_of(classdev, struct internal_container, classdev);
117 struct device *dev = classdev->dev;
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 * class_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 class_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 */
141 void
142 attribute_container_add_device(struct device *dev,
143 int (*fn)(struct attribute_container *,
144 struct device *,
145 struct class_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_printk(KERN_ERR, dev, "failed to allocate class container\n");
162 continue;
163 }
164
165 ic->cont = cont;
166 class_device_initialize(&ic->classdev);
167 ic->classdev.dev = get_device(dev);
168 ic->classdev.class = cont->class;
169 cont->class->release = attribute_container_release;
170 strcpy(ic->classdev.class_id, dev->bus_id);
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 class_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 * class_device_del() and then use
204 * attribute_container_device_trigger() to do the final put on the
205 * classdev.
206 */
207 void
208 attribute_container_remove_device(struct device *dev,
209 void (*fn)(struct attribute_container *,
210 struct device *,
211 struct class_device *))
212 {
213 struct attribute_container *cont;
214
215 mutex_lock(&attribute_container_mutex);
216 list_for_each_entry(cont, &attribute_container_list, node) {
217 struct internal_container *ic;
218 struct klist_iter iter;
219
220 if (attribute_container_no_classdevs(cont))
221 continue;
222
223 if (!cont->match(cont, dev))
224 continue;
225
226 klist_for_each_entry(ic, &cont->containers, node, &iter) {
227 if (dev != ic->classdev.dev)
228 continue;
229 klist_del(&ic->node);
230 if (fn)
231 fn(cont, dev, &ic->classdev);
232 else {
233 attribute_container_remove_attrs(&ic->classdev);
234 class_device_unregister(&ic->classdev);
235 }
236 }
237 }
238 mutex_unlock(&attribute_container_mutex);
239 }
240
241 /**
242 * attribute_container_device_trigger - execute a trigger for each matching classdev
243 *
244 * @dev: The generic device to run the trigger for
245 * @fn the function to execute for each classdev.
246 *
247 * This funcion is for executing a trigger when you need to know both
248 * the container and the classdev. If you only care about the
249 * container, then use attribute_container_trigger() instead.
250 */
251 void
252 attribute_container_device_trigger(struct device *dev,
253 int (*fn)(struct attribute_container *,
254 struct device *,
255 struct class_device *))
256 {
257 struct attribute_container *cont;
258
259 mutex_lock(&attribute_container_mutex);
260 list_for_each_entry(cont, &attribute_container_list, node) {
261 struct internal_container *ic;
262 struct klist_iter iter;
263
264 if (!cont->match(cont, dev))
265 continue;
266
267 if (attribute_container_no_classdevs(cont)) {
268 fn(cont, dev, NULL);
269 continue;
270 }
271
272 klist_for_each_entry(ic, &cont->containers, node, &iter) {
273 if (dev == ic->classdev.dev)
274 fn(cont, dev, &ic->classdev);
275 }
276 }
277 mutex_unlock(&attribute_container_mutex);
278 }
279
280 /**
281 * attribute_container_trigger - trigger a function for each matching container
282 *
283 * @dev: The generic device to activate the trigger for
284 * @fn: the function to trigger
285 *
286 * This routine triggers a function that only needs to know the
287 * matching containers (not the classdev) associated with a device.
288 * It is more lightweight than attribute_container_device_trigger, so
289 * should be used in preference unless the triggering function
290 * actually needs to know the classdev.
291 */
292 void
293 attribute_container_trigger(struct device *dev,
294 int (*fn)(struct attribute_container *,
295 struct device *))
296 {
297 struct attribute_container *cont;
298
299 mutex_lock(&attribute_container_mutex);
300 list_for_each_entry(cont, &attribute_container_list, node) {
301 if (cont->match(cont, dev))
302 fn(cont, dev);
303 }
304 mutex_unlock(&attribute_container_mutex);
305 }
306
307 /**
308 * attribute_container_add_attrs - add attributes
309 *
310 * @classdev: The class device
311 *
312 * This simply creates all the class device sysfs files from the
313 * attributes listed in the container
314 */
315 int
316 attribute_container_add_attrs(struct class_device *classdev)
317 {
318 struct attribute_container *cont =
319 attribute_container_classdev_to_container(classdev);
320 struct class_device_attribute **attrs = cont->attrs;
321 int i, error;
322
323 BUG_ON(attrs && cont->grp);
324
325 if (!attrs && !cont->grp)
326 return 0;
327
328 if (cont->grp)
329 return sysfs_create_group(&classdev->kobj, cont->grp);
330
331 for (i = 0; attrs[i]; i++) {
332 error = class_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 class_device_add
342 *
343 * @classdev: the class device to add
344 *
345 * This performs essentially the same function as class_device_add except for
346 * attribute containers, namely add the classdev to the system and then
347 * create the attribute files
348 */
349 int
350 attribute_container_add_class_device(struct class_device *classdev)
351 {
352 int error = class_device_add(classdev);
353 if (error)
354 return error;
355 return attribute_container_add_attrs(classdev);
356 }
357
358 /**
359 * attribute_container_add_class_device_adapter - simple adapter for triggers
360 *
361 * This function is identical to attribute_container_add_class_device except
362 * that it is designed to be called from the triggers
363 */
364 int
365 attribute_container_add_class_device_adapter(struct attribute_container *cont,
366 struct device *dev,
367 struct class_device *classdev)
368 {
369 return attribute_container_add_class_device(classdev);
370 }
371
372 /**
373 * attribute_container_remove_attrs - remove any attribute files
374 *
375 * @classdev: The class device to remove the files from
376 *
377 */
378 void
379 attribute_container_remove_attrs(struct class_device *classdev)
380 {
381 struct attribute_container *cont =
382 attribute_container_classdev_to_container(classdev);
383 struct class_device_attribute **attrs = cont->attrs;
384 int i;
385
386 if (!attrs && !cont->grp)
387 return;
388
389 if (cont->grp) {
390 sysfs_remove_group(&classdev->kobj, cont->grp);
391 return ;
392 }
393
394 for (i = 0; attrs[i]; i++)
395 class_device_remove_file(classdev, attrs[i]);
396 }
397
398 /**
399 * attribute_container_class_device_del - equivalent of class_device_del
400 *
401 * @classdev: the class device
402 *
403 * This function simply removes all the attribute files and then calls
404 * class_device_del.
405 */
406 void
407 attribute_container_class_device_del(struct class_device *classdev)
408 {
409 attribute_container_remove_attrs(classdev);
410 class_device_del(classdev);
411 }
412
413 /**
414 * attribute_container_find_class_device - find the corresponding class_device
415 *
416 * @cont: the container
417 * @dev: the generic device
418 *
419 * Looks up the device in the container's list of class devices and returns
420 * the corresponding class_device.
421 */
422 struct class_device *
423 attribute_container_find_class_device(struct attribute_container *cont,
424 struct device *dev)
425 {
426 struct class_device *cdev = NULL;
427 struct internal_container *ic;
428 struct klist_iter iter;
429
430 klist_for_each_entry(ic, &cont->containers, node, &iter) {
431 if (ic->classdev.dev == dev) {
432 cdev = &ic->classdev;
433 /* FIXME: must exit iterator then break */
434 klist_iter_exit(&iter);
435 break;
436 }
437 }
438
439 return cdev;
440 }
441 EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
442
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