projects/linux·blob master · refs

505 lines · 13.1 KiB

1// SPDX-License-Identifier: GPL-2.0
2/*
3 * attribute_container.c - implementation of a simple container for classes
4 *
5 * Copyright (c) 2005 - James Bottomley <[email protected]>
6 *
7 * The basic idea here is to enable a device to be attached to an
8 * aritrary numer of classes without having to allocate storage for them.
9 * Instead, the contained classes select the devices they need to attach
10 * to via a matching function.
11 */
12
13#include <linux/attribute_container.h>
14#include <linux/device.h>
15#include <linux/kernel.h>
16#include <linux/slab.h>
17#include <linux/list.h>
18#include <linux/module.h>
19#include <linux/mutex.h>
20
21#include "base.h"
22
23/* This is a private structure used to tie the classdev and the
24 * container .. it should never be visible outside this file */
25struct internal_container {
26 struct klist_node node;
27 struct attribute_container *cont;
28 struct device classdev;
29};
30
31static void internal_container_klist_get(struct klist_node *n)
32{
33 struct internal_container *ic =
34 container_of(n, struct internal_container, node);
35 get_device(&ic->classdev);
36}
37
38static void internal_container_klist_put(struct klist_node *n)
39{
40 struct internal_container *ic =
41 container_of(n, struct internal_container, node);
42 put_device(&ic->classdev);
43}
44
45
46/**
47 * attribute_container_classdev_to_container - given a classdev, return the container
48 *
49 * @classdev: the class device created by attribute_container_add_device.
50 *
51 * Returns the container associated with this classdev.
52 */
53struct attribute_container *
54attribute_container_classdev_to_container(struct device *classdev)
55{
56 struct internal_container *ic =
57 container_of(classdev, struct internal_container, classdev);
58 return ic->cont;
59}
60EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);
61
62static LIST_HEAD(attribute_container_list);
63
64static DEFINE_MUTEX(attribute_container_mutex);
65
66/**
67 * attribute_container_register - register an attribute container
68 *
69 * @cont: The container to register. This must be allocated by the
70 * callee and should also be zeroed by it.
71 */
72void
73attribute_container_register(struct attribute_container *cont)
74{
75 INIT_LIST_HEAD(&cont->node);
76 klist_init(&cont->containers, internal_container_klist_get,
77 internal_container_klist_put);
78
79 mutex_lock(&attribute_container_mutex);
80 list_add_tail(&cont->node, &attribute_container_list);
81 mutex_unlock(&attribute_container_mutex);
82}
83EXPORT_SYMBOL_GPL(attribute_container_register);
84
85/**
86 * attribute_container_unregister - remove a container registration
87 *
88 * @cont: previously registered container to remove
89 */
90int
91attribute_container_unregister(struct attribute_container *cont)
92{
93 int retval = -EBUSY;
94
95 mutex_lock(&attribute_container_mutex);
96 spin_lock(&cont->containers.k_lock);
97 if (!list_empty(&cont->containers.k_list))
98 goto out;
99 retval = 0;
100 list_del(&cont->node);
101 out:
102 spin_unlock(&cont->containers.k_lock);
103 mutex_unlock(&attribute_container_mutex);
104 return retval;
105
106}
107EXPORT_SYMBOL_GPL(attribute_container_unregister);
108
109/* private function used as class release */
110static void attribute_container_release(struct device *classdev)
111{
112 struct internal_container *ic
113 = container_of(classdev, struct internal_container, classdev);
114 struct device *dev = classdev->parent;
115
116 kfree(ic);
117 put_device(dev);
118}
119
120/**
121 * attribute_container_add_device - see if any container is interested in dev
122 *
123 * @dev: device to add attributes to
124 * @fn: function to trigger addition of class device.
125 *
126 * This function allocates storage for the class device(s) to be
127 * attached to dev (one for each matching attribute_container). If no
128 * fn is provided, the code will simply register the class device via
129 * device_add. If a function is provided, it is expected to add
130 * the class device at the appropriate time. One of the things that
131 * might be necessary is to allocate and initialise the classdev and
132 * then add it a later time. To do this, call this routine for
133 * allocation and initialisation and then use
134 * attribute_container_device_trigger() to call device_add() on
135 * it. Note: after this, the class device contains a reference to dev
136 * which is not relinquished until the release of the classdev.
137 */
138void
139attribute_container_add_device(struct device *dev,
140 int (*fn)(struct attribute_container *,
141 struct device *,
142 struct device *))
143{
144 struct attribute_container *cont;
145
146 mutex_lock(&attribute_container_mutex);
147 list_for_each_entry(cont, &attribute_container_list, node) {
148 struct internal_container *ic;
149
150 if (attribute_container_no_classdevs(cont))
151 continue;
152
153 if (!cont->match(cont, dev))
154 continue;
155
156 ic = kzalloc_obj(*ic);
157 if (!ic) {
158 dev_err(dev, "failed to allocate class container\n");
159 continue;
160 }
161
162 ic->cont = cont;
163 device_initialize(&ic->classdev);
164 ic->classdev.parent = get_device(dev);
165 ic->classdev.class = cont->class;
166 cont->class->dev_release = attribute_container_release;
167 dev_set_name(&ic->classdev, "%s", dev_name(dev));
168 if (fn)
169 fn(cont, dev, &ic->classdev);
170 else
171 attribute_container_add_class_device(&ic->classdev);
172 klist_add_tail(&ic->node, &cont->containers);
173 }
174 mutex_unlock(&attribute_container_mutex);
175}
176
177/* FIXME: can't break out of this unless klist_iter_exit is also
178 * called before doing the break
179 */
180#define klist_for_each_entry(pos, head, member, iter) \
181 for (klist_iter_init(head, iter); (pos = ({ \
182 struct klist_node *n = klist_next(iter); \
183 n ? container_of(n, typeof(*pos), member) : \
184 ({ klist_iter_exit(iter) ; NULL; }); \
185 })) != NULL;)
186
187
188/**
189 * attribute_container_remove_device - make device eligible for removal.
190 *
191 * @dev: The generic device
192 * @fn: A function to call to remove the device
193 *
194 * This routine triggers device removal. If fn is NULL, then it is
195 * simply done via device_unregister (note that if something
196 * still has a reference to the classdev, then the memory occupied
197 * will not be freed until the classdev is released). If you want a
198 * two phase release: remove from visibility and then delete the
199 * device, then you should use this routine with a fn that calls
200 * device_del() and then use attribute_container_device_trigger()
201 * to do the final put on the classdev.
202 */
203void
204attribute_container_remove_device(struct device *dev,
205 void (*fn)(struct attribute_container *,
206 struct device *,
207 struct device *))
208{
209 struct attribute_container *cont;
210
211 mutex_lock(&attribute_container_mutex);
212 list_for_each_entry(cont, &attribute_container_list, node) {
213 struct internal_container *ic;
214 struct klist_iter iter;
215
216 if (attribute_container_no_classdevs(cont))
217 continue;
218
219 if (!cont->match(cont, dev))
220 continue;
221
222 klist_for_each_entry(ic, &cont->containers, node, &iter) {
223 if (dev != ic->classdev.parent)
224 continue;
225 klist_del(&ic->node);
226 if (fn)
227 fn(cont, dev, &ic->classdev);
228 else {
229 attribute_container_remove_attrs(&ic->classdev);
230 device_unregister(&ic->classdev);
231 }
232 }
233 }
234 mutex_unlock(&attribute_container_mutex);
235}
236
237static int
238do_attribute_container_device_trigger_safe(struct device *dev,
239 struct attribute_container *cont,
240 int (*fn)(struct attribute_container *,
241 struct device *, struct device *),
242 int (*undo)(struct attribute_container *,
243 struct device *, struct device *))
244{
245 int ret;
246 struct internal_container *ic, *failed;
247 struct klist_iter iter;
248
249 if (attribute_container_no_classdevs(cont))
250 return fn(cont, dev, NULL);
251
252 klist_for_each_entry(ic, &cont->containers, node, &iter) {
253 if (dev == ic->classdev.parent) {
254 ret = fn(cont, dev, &ic->classdev);
255 if (ret) {
256 failed = ic;
257 klist_iter_exit(&iter);
258 goto fail;
259 }
260 }
261 }
262 return 0;
263
264fail:
265 if (!undo)
266 return ret;
267
268 /* Attempt to undo the work partially done. */
269 klist_for_each_entry(ic, &cont->containers, node, &iter) {
270 if (ic == failed) {
271 klist_iter_exit(&iter);
272 break;
273 }
274 if (dev == ic->classdev.parent)
275 undo(cont, dev, &ic->classdev);
276 }
277 return ret;
278}
279
280/**
281 * attribute_container_device_trigger_safe - execute a trigger for each
282 * matching classdev or fail all of them.
283 *
284 * @dev: The generic device to run the trigger for
285 * @fn: the function to execute for each classdev.
286 * @undo: A function to undo the work previously done in case of error
287 *
288 * This function is a safe version of
289 * attribute_container_device_trigger. It stops on the first error and
290 * undo the partial work that has been done, on previous classdev. It
291 * is guaranteed that either they all succeeded, or none of them
292 * succeeded.
293 */
294int
295attribute_container_device_trigger_safe(struct device *dev,
296 int (*fn)(struct attribute_container *,
297 struct device *,
298 struct device *),
299 int (*undo)(struct attribute_container *,
300 struct device *,
301 struct device *))
302{
303 struct attribute_container *cont, *failed = NULL;
304 int ret = 0;
305
306 mutex_lock(&attribute_container_mutex);
307
308 list_for_each_entry(cont, &attribute_container_list, node) {
309
310 if (!cont->match(cont, dev))
311 continue;
312
313 ret = do_attribute_container_device_trigger_safe(dev, cont,
314 fn, undo);
315 if (ret) {
316 failed = cont;
317 break;
318 }
319 }
320
321 if (ret && !WARN_ON(!undo)) {
322 list_for_each_entry(cont, &attribute_container_list, node) {
323
324 if (failed == cont)
325 break;
326
327 if (!cont->match(cont, dev))
328 continue;
329
330 do_attribute_container_device_trigger_safe(dev, cont,
331 undo, NULL);
332 }
333 }
334
335 mutex_unlock(&attribute_container_mutex);
336 return ret;
337
338}
339
340/**
341 * attribute_container_device_trigger - execute a trigger for each matching classdev
342 *
343 * @dev: The generic device to run the trigger for
344 * @fn: the function to execute for each classdev.
345 *
346 * This function is for executing a trigger when you need to know both
347 * the container and the classdev.
348 */
349void
350attribute_container_device_trigger(struct device *dev,
351 int (*fn)(struct attribute_container *,
352 struct device *,
353 struct device *))
354{
355 struct attribute_container *cont;
356
357 mutex_lock(&attribute_container_mutex);
358 list_for_each_entry(cont, &attribute_container_list, node) {
359 struct internal_container *ic;
360 struct klist_iter iter;
361
362 if (!cont->match(cont, dev))
363 continue;
364
365 if (attribute_container_no_classdevs(cont)) {
366 fn(cont, dev, NULL);
367 continue;
368 }
369
370 klist_for_each_entry(ic, &cont->containers, node, &iter) {
371 if (dev == ic->classdev.parent)
372 fn(cont, dev, &ic->classdev);
373 }
374 }
375 mutex_unlock(&attribute_container_mutex);
376}
377
378/**
379 * attribute_container_add_attrs - add attributes
380 *
381 * @classdev: The class device
382 *
383 * This simply creates all the class device sysfs files from the
384 * attributes listed in the container
385 */
386int
387attribute_container_add_attrs(struct device *classdev)
388{
389 struct attribute_container *cont =
390 attribute_container_classdev_to_container(classdev);
391 struct device_attribute **attrs = cont->attrs;
392 int i, error;
393
394 BUG_ON(attrs && cont->grp);
395
396 if (!attrs && !cont->grp)
397 return 0;
398
399 if (cont->grp)
400 return sysfs_create_group(&classdev->kobj, cont->grp);
401
402 for (i = 0; attrs[i]; i++) {
403 sysfs_attr_init(&attrs[i]->attr);
404 error = device_create_file(classdev, attrs[i]);
405 if (error)
406 return error;
407 }
408
409 return 0;
410}
411
412/**
413 * attribute_container_add_class_device - same function as device_add
414 *
415 * @classdev: the class device to add
416 *
417 * This performs essentially the same function as device_add except for
418 * attribute containers, namely add the classdev to the system and then
419 * create the attribute files
420 */
421int
422attribute_container_add_class_device(struct device *classdev)
423{
424 int error = device_add(classdev);
425
426 if (error)
427 return error;
428
429 error = attribute_container_add_attrs(classdev);
430 if (error)
431 device_del(classdev);
432
433 return error;
434}
435
436/**
437 * attribute_container_remove_attrs - remove any attribute files
438 *
439 * @classdev: The class device to remove the files from
440 *
441 */
442void
443attribute_container_remove_attrs(struct device *classdev)
444{
445 struct attribute_container *cont =
446 attribute_container_classdev_to_container(classdev);
447 struct device_attribute **attrs = cont->attrs;
448 int i;
449
450 if (!attrs && !cont->grp)
451 return;
452
453 if (cont->grp) {
454 sysfs_remove_group(&classdev->kobj, cont->grp);
455 return ;
456 }
457
458 for (i = 0; attrs[i]; i++)
459 device_remove_file(classdev, attrs[i]);
460}
461
462/**
463 * attribute_container_class_device_del - equivalent of class_device_del
464 *
465 * @classdev: the class device
466 *
467 * This function simply removes all the attribute files and then calls
468 * device_del.
469 */
470void
471attribute_container_class_device_del(struct device *classdev)
472{
473 attribute_container_remove_attrs(classdev);
474 device_del(classdev);
475}
476
477/**
478 * attribute_container_find_class_device - find the corresponding class_device
479 *
480 * @cont: the container
481 * @dev: the generic device
482 *
483 * Looks up the device in the container's list of class devices and returns
484 * the corresponding class_device.
485 */
486struct device *
487attribute_container_find_class_device(struct attribute_container *cont,
488 struct device *dev)
489{
490 struct device *cdev = NULL;
491 struct internal_container *ic;
492 struct klist_iter iter;
493
494 klist_for_each_entry(ic, &cont->containers, node, &iter) {
495 if (ic->classdev.parent == dev) {
496 cdev = &ic->classdev;
497 /* FIXME: must exit iterator then break */
498 klist_iter_exit(&iter);
499 break;
500 }
501 }
502
503 return cdev;
504}
505EXPORT_SYMBOL_GPL(attribute_container_find_class_device);