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 */
26 struct internal_container {
27 	struct klist_node node;
28 	struct attribute_container *cont;
29 	struct device classdev;
30 };
31 
32 static 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 
39 static 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  */
54 struct attribute_container *
55 attribute_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 }
61 EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);
62 
63 static LIST_HEAD(attribute_container_list);
64 
65 static 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  */
73 int
74 attribute_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 }
86 EXPORT_SYMBOL_GPL(attribute_container_register);
87 
88 /**
89  * attribute_container_unregister - remove a container registration
90  *
91  * @cont: previously registered container to remove
92  */
93 int
94 attribute_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 }
109 EXPORT_SYMBOL_GPL(attribute_container_unregister);
110 
111 /* private function used as class release */
112 static 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  */
140 void
141 attribute_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  */
205 void
206 attribute_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 
239 /**
240  * attribute_container_device_trigger - execute a trigger for each matching classdev
241  *
242  * @dev:  The generic device to run the trigger for
243  * @fn	  the function to execute for each classdev.
244  *
245  * This funcion is for executing a trigger when you need to know both
246  * the container and the classdev.  If you only care about the
247  * container, then use attribute_container_trigger() instead.
248  */
249 void
250 attribute_container_device_trigger(struct device *dev,
251 				   int (*fn)(struct attribute_container *,
252 					     struct device *,
253 					     struct device *))
254 {
255 	struct attribute_container *cont;
256 
257 	mutex_lock(&attribute_container_mutex);
258 	list_for_each_entry(cont, &attribute_container_list, node) {
259 		struct internal_container *ic;
260 		struct klist_iter iter;
261 
262 		if (!cont->match(cont, dev))
263 			continue;
264 
265 		if (attribute_container_no_classdevs(cont)) {
266 			fn(cont, dev, NULL);
267 			continue;
268 		}
269 
270 		klist_for_each_entry(ic, &cont->containers, node, &iter) {
271 			if (dev == ic->classdev.parent)
272 				fn(cont, dev, &ic->classdev);
273 		}
274 	}
275 	mutex_unlock(&attribute_container_mutex);
276 }
277 
278 /**
279  * attribute_container_trigger - trigger a function for each matching container
280  *
281  * @dev:  The generic device to activate the trigger for
282  * @fn:	  the function to trigger
283  *
284  * This routine triggers a function that only needs to know the
285  * matching containers (not the classdev) associated with a device.
286  * It is more lightweight than attribute_container_device_trigger, so
287  * should be used in preference unless the triggering function
288  * actually needs to know the classdev.
289  */
290 void
291 attribute_container_trigger(struct device *dev,
292 			    int (*fn)(struct attribute_container *,
293 				      struct device *))
294 {
295 	struct attribute_container *cont;
296 
297 	mutex_lock(&attribute_container_mutex);
298 	list_for_each_entry(cont, &attribute_container_list, node) {
299 		if (cont->match(cont, dev))
300 			fn(cont, dev);
301 	}
302 	mutex_unlock(&attribute_container_mutex);
303 }
304 
305 /**
306  * attribute_container_add_attrs - add attributes
307  *
308  * @classdev: The class device
309  *
310  * This simply creates all the class device sysfs files from the
311  * attributes listed in the container
312  */
313 int
314 attribute_container_add_attrs(struct device *classdev)
315 {
316 	struct attribute_container *cont =
317 		attribute_container_classdev_to_container(classdev);
318 	struct device_attribute **attrs = cont->attrs;
319 	int i, error;
320 
321 	BUG_ON(attrs && cont->grp);
322 
323 	if (!attrs && !cont->grp)
324 		return 0;
325 
326 	if (cont->grp)
327 		return sysfs_create_group(&classdev->kobj, cont->grp);
328 
329 	for (i = 0; attrs[i]; i++) {
330 		sysfs_attr_init(&attrs[i]->attr);
331 		error = device_create_file(classdev, attrs[i]);
332 		if (error)
333 			return error;
334 	}
335 
336 	return 0;
337 }
338 
339 /**
340  * attribute_container_add_class_device - same function as device_add
341  *
342  * @classdev:	the class device to add
343  *
344  * This performs essentially the same function as device_add except for
345  * attribute containers, namely add the classdev to the system and then
346  * create the attribute files
347  */
348 int
349 attribute_container_add_class_device(struct device *classdev)
350 {
351 	int error = device_add(classdev);
352 	if (error)
353 		return error;
354 	return attribute_container_add_attrs(classdev);
355 }
356 
357 /**
358  * attribute_container_add_class_device_adapter - simple adapter for triggers
359  *
360  * This function is identical to attribute_container_add_class_device except
361  * that it is designed to be called from the triggers
362  */
363 int
364 attribute_container_add_class_device_adapter(struct attribute_container *cont,
365 					     struct device *dev,
366 					     struct device *classdev)
367 {
368 	return attribute_container_add_class_device(classdev);
369 }
370 
371 /**
372  * attribute_container_remove_attrs - remove any attribute files
373  *
374  * @classdev: The class device to remove the files from
375  *
376  */
377 void
378 attribute_container_remove_attrs(struct device *classdev)
379 {
380 	struct attribute_container *cont =
381 		attribute_container_classdev_to_container(classdev);
382 	struct device_attribute **attrs = cont->attrs;
383 	int i;
384 
385 	if (!attrs && !cont->grp)
386 		return;
387 
388 	if (cont->grp) {
389 		sysfs_remove_group(&classdev->kobj, cont->grp);
390 		return ;
391 	}
392 
393 	for (i = 0; attrs[i]; i++)
394 		device_remove_file(classdev, attrs[i]);
395 }
396 
397 /**
398  * attribute_container_class_device_del - equivalent of class_device_del
399  *
400  * @classdev: the class device
401  *
402  * This function simply removes all the attribute files and then calls
403  * device_del.
404  */
405 void
406 attribute_container_class_device_del(struct device *classdev)
407 {
408 	attribute_container_remove_attrs(classdev);
409 	device_del(classdev);
410 }
411 
412 /**
413  * attribute_container_find_class_device - find the corresponding class_device
414  *
415  * @cont:	the container
416  * @dev:	the generic device
417  *
418  * Looks up the device in the container's list of class devices and returns
419  * the corresponding class_device.
420  */
421 struct device *
422 attribute_container_find_class_device(struct attribute_container *cont,
423 				      struct device *dev)
424 {
425 	struct device *cdev = NULL;
426 	struct internal_container *ic;
427 	struct klist_iter iter;
428 
429 	klist_for_each_entry(ic, &cont->containers, node, &iter) {
430 		if (ic->classdev.parent == dev) {
431 			cdev = &ic->classdev;
432 			/* FIXME: must exit iterator then break */
433 			klist_iter_exit(&iter);
434 			break;
435 		}
436 	}
437 
438 	return cdev;
439 }
440 EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
441