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 <James.Bottomley@steeleye.com> |
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 */ |
25 | struct internal_container { |
26 | struct klist_node node; |
27 | struct attribute_container *cont; |
28 | struct device classdev; |
29 | }; |
30 | |
31 | static 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(dev: &ic->classdev); |
36 | } |
37 | |
38 | static 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(dev: &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 | */ |
53 | struct attribute_container * |
54 | attribute_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 | } |
60 | EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container); |
61 | |
62 | static LIST_HEAD(attribute_container_list); |
63 | |
64 | static 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 | */ |
72 | int |
73 | attribute_container_register(struct attribute_container *cont) |
74 | { |
75 | INIT_LIST_HEAD(list: &cont->node); |
76 | klist_init(k: &cont->containers, get: internal_container_klist_get, |
77 | put: internal_container_klist_put); |
78 | |
79 | mutex_lock(&attribute_container_mutex); |
80 | list_add_tail(new: &cont->node, head: &attribute_container_list); |
81 | mutex_unlock(lock: &attribute_container_mutex); |
82 | |
83 | return 0; |
84 | } |
85 | EXPORT_SYMBOL_GPL(attribute_container_register); |
86 | |
87 | /** |
88 | * attribute_container_unregister - remove a container registration |
89 | * |
90 | * @cont: previously registered container to remove |
91 | */ |
92 | int |
93 | attribute_container_unregister(struct attribute_container *cont) |
94 | { |
95 | int retval = -EBUSY; |
96 | |
97 | mutex_lock(&attribute_container_mutex); |
98 | spin_lock(lock: &cont->containers.k_lock); |
99 | if (!list_empty(head: &cont->containers.k_list)) |
100 | goto out; |
101 | retval = 0; |
102 | list_del(entry: &cont->node); |
103 | out: |
104 | spin_unlock(lock: &cont->containers.k_lock); |
105 | mutex_unlock(lock: &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(objp: 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(atc: cont)) |
153 | continue; |
154 | |
155 | if (!cont->match(cont, dev)) |
156 | continue; |
157 | |
158 | ic = kzalloc(size: 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(dev: &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(dev: &ic->classdev, name: "%s" , dev_name(dev)); |
170 | if (fn) |
171 | fn(cont, dev, &ic->classdev); |
172 | else |
173 | attribute_container_add_class_device(classdev: &ic->classdev); |
174 | klist_add_tail(n: &ic->node, k: &cont->containers); |
175 | } |
176 | mutex_unlock(lock: &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(atc: 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(n: &ic->node); |
228 | if (fn) |
229 | fn(cont, dev, &ic->classdev); |
230 | else { |
231 | attribute_container_remove_attrs(classdev: &ic->classdev); |
232 | device_unregister(dev: &ic->classdev); |
233 | } |
234 | } |
235 | } |
236 | mutex_unlock(lock: &attribute_container_mutex); |
237 | } |
238 | |
239 | static int |
240 | do_attribute_container_device_trigger_safe(struct device *dev, |
241 | struct attribute_container *cont, |
242 | int (*fn)(struct attribute_container *, |
243 | struct device *, struct device *), |
244 | int (*undo)(struct attribute_container *, |
245 | struct device *, struct device *)) |
246 | { |
247 | int ret; |
248 | struct internal_container *ic, *failed; |
249 | struct klist_iter iter; |
250 | |
251 | if (attribute_container_no_classdevs(atc: cont)) |
252 | return fn(cont, dev, NULL); |
253 | |
254 | klist_for_each_entry(ic, &cont->containers, node, &iter) { |
255 | if (dev == ic->classdev.parent) { |
256 | ret = fn(cont, dev, &ic->classdev); |
257 | if (ret) { |
258 | failed = ic; |
259 | klist_iter_exit(i: &iter); |
260 | goto fail; |
261 | } |
262 | } |
263 | } |
264 | return 0; |
265 | |
266 | fail: |
267 | if (!undo) |
268 | return ret; |
269 | |
270 | /* Attempt to undo the work partially done. */ |
271 | klist_for_each_entry(ic, &cont->containers, node, &iter) { |
272 | if (ic == failed) { |
273 | klist_iter_exit(i: &iter); |
274 | break; |
275 | } |
276 | if (dev == ic->classdev.parent) |
277 | undo(cont, dev, &ic->classdev); |
278 | } |
279 | return ret; |
280 | } |
281 | |
282 | /** |
283 | * attribute_container_device_trigger_safe - execute a trigger for each |
284 | * matching classdev or fail all of them. |
285 | * |
286 | * @dev: The generic device to run the trigger for |
287 | * @fn: the function to execute for each classdev. |
288 | * @undo: A function to undo the work previously done in case of error |
289 | * |
290 | * This function is a safe version of |
291 | * attribute_container_device_trigger. It stops on the first error and |
292 | * undo the partial work that has been done, on previous classdev. It |
293 | * is guaranteed that either they all succeeded, or none of them |
294 | * succeeded. |
295 | */ |
296 | int |
297 | attribute_container_device_trigger_safe(struct device *dev, |
298 | int (*fn)(struct attribute_container *, |
299 | struct device *, |
300 | struct device *), |
301 | int (*undo)(struct attribute_container *, |
302 | struct device *, |
303 | struct device *)) |
304 | { |
305 | struct attribute_container *cont, *failed = NULL; |
306 | int ret = 0; |
307 | |
308 | mutex_lock(&attribute_container_mutex); |
309 | |
310 | list_for_each_entry(cont, &attribute_container_list, node) { |
311 | |
312 | if (!cont->match(cont, dev)) |
313 | continue; |
314 | |
315 | ret = do_attribute_container_device_trigger_safe(dev, cont, |
316 | fn, undo); |
317 | if (ret) { |
318 | failed = cont; |
319 | break; |
320 | } |
321 | } |
322 | |
323 | if (ret && !WARN_ON(!undo)) { |
324 | list_for_each_entry(cont, &attribute_container_list, node) { |
325 | |
326 | if (failed == cont) |
327 | break; |
328 | |
329 | if (!cont->match(cont, dev)) |
330 | continue; |
331 | |
332 | do_attribute_container_device_trigger_safe(dev, cont, |
333 | fn: undo, NULL); |
334 | } |
335 | } |
336 | |
337 | mutex_unlock(lock: &attribute_container_mutex); |
338 | return ret; |
339 | |
340 | } |
341 | |
342 | /** |
343 | * attribute_container_device_trigger - execute a trigger for each matching classdev |
344 | * |
345 | * @dev: The generic device to run the trigger for |
346 | * @fn: the function to execute for each classdev. |
347 | * |
348 | * This function is for executing a trigger when you need to know both |
349 | * the container and the classdev. If you only care about the |
350 | * container, then use attribute_container_trigger() instead. |
351 | */ |
352 | void |
353 | attribute_container_device_trigger(struct device *dev, |
354 | int (*fn)(struct attribute_container *, |
355 | struct device *, |
356 | struct device *)) |
357 | { |
358 | struct attribute_container *cont; |
359 | |
360 | mutex_lock(&attribute_container_mutex); |
361 | list_for_each_entry(cont, &attribute_container_list, node) { |
362 | struct internal_container *ic; |
363 | struct klist_iter iter; |
364 | |
365 | if (!cont->match(cont, dev)) |
366 | continue; |
367 | |
368 | if (attribute_container_no_classdevs(atc: cont)) { |
369 | fn(cont, dev, NULL); |
370 | continue; |
371 | } |
372 | |
373 | klist_for_each_entry(ic, &cont->containers, node, &iter) { |
374 | if (dev == ic->classdev.parent) |
375 | fn(cont, dev, &ic->classdev); |
376 | } |
377 | } |
378 | mutex_unlock(lock: &attribute_container_mutex); |
379 | } |
380 | |
381 | /** |
382 | * attribute_container_trigger - trigger a function for each matching container |
383 | * |
384 | * @dev: The generic device to activate the trigger for |
385 | * @fn: the function to trigger |
386 | * |
387 | * This routine triggers a function that only needs to know the |
388 | * matching containers (not the classdev) associated with a device. |
389 | * It is more lightweight than attribute_container_device_trigger, so |
390 | * should be used in preference unless the triggering function |
391 | * actually needs to know the classdev. |
392 | */ |
393 | void |
394 | attribute_container_trigger(struct device *dev, |
395 | int (*fn)(struct attribute_container *, |
396 | struct device *)) |
397 | { |
398 | struct attribute_container *cont; |
399 | |
400 | mutex_lock(&attribute_container_mutex); |
401 | list_for_each_entry(cont, &attribute_container_list, node) { |
402 | if (cont->match(cont, dev)) |
403 | fn(cont, dev); |
404 | } |
405 | mutex_unlock(lock: &attribute_container_mutex); |
406 | } |
407 | |
408 | /** |
409 | * attribute_container_add_attrs - add attributes |
410 | * |
411 | * @classdev: The class device |
412 | * |
413 | * This simply creates all the class device sysfs files from the |
414 | * attributes listed in the container |
415 | */ |
416 | int |
417 | attribute_container_add_attrs(struct device *classdev) |
418 | { |
419 | struct attribute_container *cont = |
420 | attribute_container_classdev_to_container(classdev); |
421 | struct device_attribute **attrs = cont->attrs; |
422 | int i, error; |
423 | |
424 | BUG_ON(attrs && cont->grp); |
425 | |
426 | if (!attrs && !cont->grp) |
427 | return 0; |
428 | |
429 | if (cont->grp) |
430 | return sysfs_create_group(kobj: &classdev->kobj, grp: cont->grp); |
431 | |
432 | for (i = 0; attrs[i]; i++) { |
433 | sysfs_attr_init(&attrs[i]->attr); |
434 | error = device_create_file(device: classdev, entry: attrs[i]); |
435 | if (error) |
436 | return error; |
437 | } |
438 | |
439 | return 0; |
440 | } |
441 | |
442 | /** |
443 | * attribute_container_add_class_device - same function as device_add |
444 | * |
445 | * @classdev: the class device to add |
446 | * |
447 | * This performs essentially the same function as device_add except for |
448 | * attribute containers, namely add the classdev to the system and then |
449 | * create the attribute files |
450 | */ |
451 | int |
452 | attribute_container_add_class_device(struct device *classdev) |
453 | { |
454 | int error = device_add(dev: classdev); |
455 | |
456 | if (error) |
457 | return error; |
458 | return attribute_container_add_attrs(classdev); |
459 | } |
460 | |
461 | /** |
462 | * attribute_container_add_class_device_adapter - simple adapter for triggers |
463 | * |
464 | * @cont: the container to register. |
465 | * @dev: the generic device to activate the trigger for |
466 | * @classdev: the class device to add |
467 | * |
468 | * This function is identical to attribute_container_add_class_device except |
469 | * that it is designed to be called from the triggers |
470 | */ |
471 | int |
472 | attribute_container_add_class_device_adapter(struct attribute_container *cont, |
473 | struct device *dev, |
474 | struct device *classdev) |
475 | { |
476 | return attribute_container_add_class_device(classdev); |
477 | } |
478 | |
479 | /** |
480 | * attribute_container_remove_attrs - remove any attribute files |
481 | * |
482 | * @classdev: The class device to remove the files from |
483 | * |
484 | */ |
485 | void |
486 | attribute_container_remove_attrs(struct device *classdev) |
487 | { |
488 | struct attribute_container *cont = |
489 | attribute_container_classdev_to_container(classdev); |
490 | struct device_attribute **attrs = cont->attrs; |
491 | int i; |
492 | |
493 | if (!attrs && !cont->grp) |
494 | return; |
495 | |
496 | if (cont->grp) { |
497 | sysfs_remove_group(kobj: &classdev->kobj, grp: cont->grp); |
498 | return ; |
499 | } |
500 | |
501 | for (i = 0; attrs[i]; i++) |
502 | device_remove_file(dev: classdev, attr: attrs[i]); |
503 | } |
504 | |
505 | /** |
506 | * attribute_container_class_device_del - equivalent of class_device_del |
507 | * |
508 | * @classdev: the class device |
509 | * |
510 | * This function simply removes all the attribute files and then calls |
511 | * device_del. |
512 | */ |
513 | void |
514 | attribute_container_class_device_del(struct device *classdev) |
515 | { |
516 | attribute_container_remove_attrs(classdev); |
517 | device_del(dev: classdev); |
518 | } |
519 | |
520 | /** |
521 | * attribute_container_find_class_device - find the corresponding class_device |
522 | * |
523 | * @cont: the container |
524 | * @dev: the generic device |
525 | * |
526 | * Looks up the device in the container's list of class devices and returns |
527 | * the corresponding class_device. |
528 | */ |
529 | struct device * |
530 | attribute_container_find_class_device(struct attribute_container *cont, |
531 | struct device *dev) |
532 | { |
533 | struct device *cdev = NULL; |
534 | struct internal_container *ic; |
535 | struct klist_iter iter; |
536 | |
537 | klist_for_each_entry(ic, &cont->containers, node, &iter) { |
538 | if (ic->classdev.parent == dev) { |
539 | cdev = &ic->classdev; |
540 | /* FIXME: must exit iterator then break */ |
541 | klist_iter_exit(i: &iter); |
542 | break; |
543 | } |
544 | } |
545 | |
546 | return cdev; |
547 | } |
548 | EXPORT_SYMBOL_GPL(attribute_container_find_class_device); |
549 | |