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 */
26 struct internal_container {
27 	struct klist_node node;
28 	struct attribute_container *cont;
29 	struct class_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 	class_device_get(&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 	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  */
54 struct attribute_container *
55 attribute_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 }
61 EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);
62 
63 static struct list_head attribute_container_list;
64 
65 static DECLARE_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 	down(&attribute_container_mutex);
81 	list_add_tail(&cont->node, &attribute_container_list);
82 	up(&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 	down(&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 	up(&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 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  */
140 void
141 attribute_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 	down(&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 	up(&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 class_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  * class_device_del() and then use
203  * attribute_container_device_trigger() to do the final put on the
204  * classdev.
205  */
206 void
207 attribute_container_remove_device(struct device *dev,
208 				  void (*fn)(struct attribute_container *,
209 					     struct device *,
210 					     struct class_device *))
211 {
212 	struct attribute_container *cont;
213 
214 	down(&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.dev)
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 				class_device_unregister(&ic->classdev);
234 			}
235 		}
236 	}
237 	up(&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 class_device *))
255 {
256 	struct attribute_container *cont;
257 
258 	down(&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.dev)
273 				fn(cont, dev, &ic->classdev);
274 		}
275 	}
276 	up(&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 	down(&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 	up(&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 class_device *classdev)
316 {
317 	struct attribute_container *cont =
318 		attribute_container_classdev_to_container(classdev);
319 	struct class_device_attribute **attrs =	cont->attrs;
320 	int i, error;
321 
322 	if (!attrs)
323 		return 0;
324 
325 	for (i = 0; attrs[i]; i++) {
326 		error = class_device_create_file(classdev, attrs[i]);
327 		if (error)
328 			return error;
329 	}
330 
331 	return 0;
332 }
333 
334 /**
335  * attribute_container_add_class_device - same function as class_device_add
336  *
337  * @classdev:	the class device to add
338  *
339  * This performs essentially the same function as class_device_add except for
340  * attribute containers, namely add the classdev to the system and then
341  * create the attribute files
342  */
343 int
344 attribute_container_add_class_device(struct class_device *classdev)
345 {
346 	int error = class_device_add(classdev);
347 	if (error)
348 		return error;
349 	return attribute_container_add_attrs(classdev);
350 }
351 
352 /**
353  * attribute_container_add_class_device_adapter - simple adapter for triggers
354  *
355  * This function is identical to attribute_container_add_class_device except
356  * that it is designed to be called from the triggers
357  */
358 int
359 attribute_container_add_class_device_adapter(struct attribute_container *cont,
360 					     struct device *dev,
361 					     struct class_device *classdev)
362 {
363 	return attribute_container_add_class_device(classdev);
364 }
365 
366 /**
367  * attribute_container_remove_attrs - remove any attribute files
368  *
369  * @classdev: The class device to remove the files from
370  *
371  */
372 void
373 attribute_container_remove_attrs(struct class_device *classdev)
374 {
375 	struct attribute_container *cont =
376 		attribute_container_classdev_to_container(classdev);
377 	struct class_device_attribute **attrs =	cont->attrs;
378 	int i;
379 
380 	if (!attrs)
381 		return;
382 
383 	for (i = 0; attrs[i]; i++)
384 		class_device_remove_file(classdev, attrs[i]);
385 }
386 
387 /**
388  * attribute_container_class_device_del - equivalent of class_device_del
389  *
390  * @classdev: the class device
391  *
392  * This function simply removes all the attribute files and then calls
393  * class_device_del.
394  */
395 void
396 attribute_container_class_device_del(struct class_device *classdev)
397 {
398 	attribute_container_remove_attrs(classdev);
399 	class_device_del(classdev);
400 }
401 
402 /**
403  * attribute_container_find_class_device - find the corresponding class_device
404  *
405  * @cont:	the container
406  * @dev:	the generic device
407  *
408  * Looks up the device in the container's list of class devices and returns
409  * the corresponding class_device.
410  */
411 struct class_device *
412 attribute_container_find_class_device(struct attribute_container *cont,
413 				      struct device *dev)
414 {
415 	struct class_device *cdev = NULL;
416 	struct internal_container *ic;
417 	struct klist_iter iter;
418 
419 	klist_for_each_entry(ic, &cont->containers, node, &iter) {
420 		if (ic->classdev.dev == dev) {
421 			cdev = &ic->classdev;
422 			/* FIXME: must exit iterator then break */
423 			klist_iter_exit(&iter);
424 			break;
425 		}
426 	}
427 
428 	return cdev;
429 }
430 EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
431 
432 int __init
433 attribute_container_init(void)
434 {
435 	INIT_LIST_HEAD(&attribute_container_list);
436 	return 0;
437 }
438