Root/drivers/base/attribute_container.c

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 */
27struct internal_container {
28    struct klist_node node;
29    struct attribute_container *cont;
30    struct device classdev;
31};
32
33static 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
40static 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 */
55struct attribute_container *
56attribute_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}
62EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);
63
64static LIST_HEAD(attribute_container_list);
65
66static 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 */
74int
75attribute_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}
87EXPORT_SYMBOL_GPL(attribute_container_register);
88
89/**
90 * attribute_container_unregister - remove a container registration
91 *
92 * @cont: previously registered container to remove
93 */
94int
95attribute_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}
110EXPORT_SYMBOL_GPL(attribute_container_unregister);
111
112/* private function used as class release */
113static 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 */
141void
142attribute_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_printk(KERN_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, 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 */
206void
207attribute_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 */
250void
251attribute_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 */
291void
292attribute_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 */
314int
315attribute_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 */
349int
350attribute_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 */
364int
365attribute_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 */
378void
379attribute_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 */
406void
407attribute_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 */
422struct device *
423attribute_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}
441EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
442

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