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 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 	get_device(&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 	put_device(&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 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 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  */
141 void
142 attribute_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  */
206 void
207 attribute_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  */
250 void
251 attribute_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  */
291 void
292 attribute_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  */
314 int
315 attribute_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  */
349 int
350 attribute_container_add_class_device(struct device *classdev)
351 {
352 	int error = 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 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 device *classdev)
380 {
381 	struct attribute_container *cont =
382 		attribute_container_classdev_to_container(classdev);
383 	struct 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 		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  * device_del.
405  */
406 void
407 attribute_container_class_device_del(struct device *classdev)
408 {
409 	attribute_container_remove_attrs(classdev);
410 	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 device *
423 attribute_container_find_class_device(struct attribute_container *cont,
424 				      struct device *dev)
425 {
426 	struct 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.parent == 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