projects/linux·blob v4.1 · refs

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1/*
2 * Componentized device handling.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * This is work in progress. We gather up the component devices into a list,
9 * and bind them when instructed. At the moment, we're specific to the DRM
10 * subsystem, and only handles one master device, but this doesn't have to be
11 * the case.
12 */
13#include <linux/component.h>
14#include <linux/device.h>
15#include <linux/kref.h>
16#include <linux/list.h>
17#include <linux/module.h>
18#include <linux/mutex.h>
19#include <linux/slab.h>
20
21struct component_match {
22 size_t alloc;
23 size_t num;
24 struct {
25 void *data;
26 int (*fn)(struct device *, void *);
27 } compare[0];
28};
29
30struct master {
31 struct list_head node;
32 struct list_head components;
33 bool bound;
34
35 const struct component_master_ops *ops;
36 struct device *dev;
37 struct component_match *match;
38};
39
40struct component {
41 struct list_head node;
42 struct list_head master_node;
43 struct master *master;
44 bool bound;
45
46 const struct component_ops *ops;
47 struct device *dev;
48};
49
50static DEFINE_MUTEX(component_mutex);
51static LIST_HEAD(component_list);
52static LIST_HEAD(masters);
53
54static struct master *__master_find(struct device *dev,
55 const struct component_master_ops *ops)
56{
57 struct master *m;
58
59 list_for_each_entry(m, &masters, node)
60 if (m->dev == dev && (!ops || m->ops == ops))
61 return m;
62
63 return NULL;
64}
65
66/* Attach an unattached component to a master. */
67static void component_attach_master(struct master *master, struct component *c)
68{
69 c->master = master;
70
71 list_add_tail(&c->master_node, &master->components);
72}
73
74/* Detach a component from a master. */
75static void component_detach_master(struct master *master, struct component *c)
76{
77 list_del(&c->master_node);
78
79 c->master = NULL;
80}
81
82/*
83 * Add a component to a master, finding the component via the compare
84 * function and compare data. This is safe to call for duplicate matches
85 * and will not result in the same component being added multiple times.
86 */
87int component_master_add_child(struct master *master,
88 int (*compare)(struct device *, void *), void *compare_data)
89{
90 struct component *c;
91 int ret = -ENXIO;
92
93 list_for_each_entry(c, &component_list, node) {
94 if (c->master && c->master != master)
95 continue;
96
97 if (compare(c->dev, compare_data)) {
98 if (!c->master)
99 component_attach_master(master, c);
100 ret = 0;
101 break;
102 }
103 }
104
105 return ret;
106}
107EXPORT_SYMBOL_GPL(component_master_add_child);
108
109static int find_components(struct master *master)
110{
111 struct component_match *match = master->match;
112 size_t i;
113 int ret = 0;
114
115 if (!match) {
116 /*
117 * Search the list of components, looking for components that
118 * belong to this master, and attach them to the master.
119 */
120 return master->ops->add_components(master->dev, master);
121 }
122
123 /*
124 * Scan the array of match functions and attach
125 * any components which are found to this master.
126 */
127 for (i = 0; i < match->num; i++) {
128 ret = component_master_add_child(master,
129 match->compare[i].fn,
130 match->compare[i].data);
131 if (ret)
132 break;
133 }
134 return ret;
135}
136
137/* Detach all attached components from this master */
138static void master_remove_components(struct master *master)
139{
140 while (!list_empty(&master->components)) {
141 struct component *c = list_first_entry(&master->components,
142 struct component, master_node);
143
144 WARN_ON(c->master != master);
145
146 component_detach_master(master, c);
147 }
148}
149
150/*
151 * Try to bring up a master. If component is NULL, we're interested in
152 * this master, otherwise it's a component which must be present to try
153 * and bring up the master.
154 *
155 * Returns 1 for successful bringup, 0 if not ready, or -ve errno.
156 */
157static int try_to_bring_up_master(struct master *master,
158 struct component *component)
159{
160 int ret;
161
162 if (master->bound)
163 return 0;
164
165 /*
166 * Search the list of components, looking for components that
167 * belong to this master, and attach them to the master.
168 */
169 if (find_components(master)) {
170 /* Failed to find all components */
171 ret = 0;
172 goto out;
173 }
174
175 if (component && component->master != master) {
176 ret = 0;
177 goto out;
178 }
179
180 if (!devres_open_group(master->dev, NULL, GFP_KERNEL)) {
181 ret = -ENOMEM;
182 goto out;
183 }
184
185 /* Found all components */
186 ret = master->ops->bind(master->dev);
187 if (ret < 0) {
188 devres_release_group(master->dev, NULL);
189 dev_info(master->dev, "master bind failed: %d\n", ret);
190 goto out;
191 }
192
193 master->bound = true;
194 return 1;
195
196out:
197 master_remove_components(master);
198
199 return ret;
200}
201
202static int try_to_bring_up_masters(struct component *component)
203{
204 struct master *m;
205 int ret = 0;
206
207 list_for_each_entry(m, &masters, node) {
208 ret = try_to_bring_up_master(m, component);
209 if (ret != 0)
210 break;
211 }
212
213 return ret;
214}
215
216static void take_down_master(struct master *master)
217{
218 if (master->bound) {
219 master->ops->unbind(master->dev);
220 devres_release_group(master->dev, NULL);
221 master->bound = false;
222 }
223
224 master_remove_components(master);
225}
226
227static size_t component_match_size(size_t num)
228{
229 return offsetof(struct component_match, compare[num]);
230}
231
232static struct component_match *component_match_realloc(struct device *dev,
233 struct component_match *match, size_t num)
234{
235 struct component_match *new;
236
237 if (match && match->alloc == num)
238 return match;
239
240 new = devm_kmalloc(dev, component_match_size(num), GFP_KERNEL);
241 if (!new)
242 return ERR_PTR(-ENOMEM);
243
244 if (match) {
245 memcpy(new, match, component_match_size(min(match->num, num)));
246 devm_kfree(dev, match);
247 } else {
248 new->num = 0;
249 }
250
251 new->alloc = num;
252
253 return new;
254}
255
256/*
257 * Add a component to be matched.
258 *
259 * The match array is first created or extended if necessary.
260 */
261void component_match_add(struct device *dev, struct component_match **matchptr,
262 int (*compare)(struct device *, void *), void *compare_data)
263{
264 struct component_match *match = *matchptr;
265
266 if (IS_ERR(match))
267 return;
268
269 if (!match || match->num == match->alloc) {
270 size_t new_size = match ? match->alloc + 16 : 15;
271
272 match = component_match_realloc(dev, match, new_size);
273
274 *matchptr = match;
275
276 if (IS_ERR(match))
277 return;
278 }
279
280 match->compare[match->num].fn = compare;
281 match->compare[match->num].data = compare_data;
282 match->num++;
283}
284EXPORT_SYMBOL(component_match_add);
285
286int component_master_add_with_match(struct device *dev,
287 const struct component_master_ops *ops,
288 struct component_match *match)
289{
290 struct master *master;
291 int ret;
292
293 if (ops->add_components && match)
294 return -EINVAL;
295
296 if (match) {
297 /* Reallocate the match array for its true size */
298 match = component_match_realloc(dev, match, match->num);
299 if (IS_ERR(match))
300 return PTR_ERR(match);
301 }
302
303 master = kzalloc(sizeof(*master), GFP_KERNEL);
304 if (!master)
305 return -ENOMEM;
306
307 master->dev = dev;
308 master->ops = ops;
309 master->match = match;
310 INIT_LIST_HEAD(&master->components);
311
312 /* Add to the list of available masters. */
313 mutex_lock(&component_mutex);
314 list_add(&master->node, &masters);
315
316 ret = try_to_bring_up_master(master, NULL);
317
318 if (ret < 0) {
319 /* Delete off the list if we weren't successful */
320 list_del(&master->node);
321 kfree(master);
322 }
323 mutex_unlock(&component_mutex);
324
325 return ret < 0 ? ret : 0;
326}
327EXPORT_SYMBOL_GPL(component_master_add_with_match);
328
329int component_master_add(struct device *dev,
330 const struct component_master_ops *ops)
331{
332 return component_master_add_with_match(dev, ops, NULL);
333}
334EXPORT_SYMBOL_GPL(component_master_add);
335
336void component_master_del(struct device *dev,
337 const struct component_master_ops *ops)
338{
339 struct master *master;
340
341 mutex_lock(&component_mutex);
342 master = __master_find(dev, ops);
343 if (master) {
344 take_down_master(master);
345
346 list_del(&master->node);
347 kfree(master);
348 }
349 mutex_unlock(&component_mutex);
350}
351EXPORT_SYMBOL_GPL(component_master_del);
352
353static void component_unbind(struct component *component,
354 struct master *master, void *data)
355{
356 WARN_ON(!component->bound);
357
358 component->ops->unbind(component->dev, master->dev, data);
359 component->bound = false;
360
361 /* Release all resources claimed in the binding of this component */
362 devres_release_group(component->dev, component);
363}
364
365void component_unbind_all(struct device *master_dev, void *data)
366{
367 struct master *master;
368 struct component *c;
369
370 WARN_ON(!mutex_is_locked(&component_mutex));
371
372 master = __master_find(master_dev, NULL);
373 if (!master)
374 return;
375
376 list_for_each_entry_reverse(c, &master->components, master_node)
377 component_unbind(c, master, data);
378}
379EXPORT_SYMBOL_GPL(component_unbind_all);
380
381static int component_bind(struct component *component, struct master *master,
382 void *data)
383{
384 int ret;
385
386 /*
387 * Each component initialises inside its own devres group.
388 * This allows us to roll-back a failed component without
389 * affecting anything else.
390 */
391 if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
392 return -ENOMEM;
393
394 /*
395 * Also open a group for the device itself: this allows us
396 * to release the resources claimed against the sub-device
397 * at the appropriate moment.
398 */
399 if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
400 devres_release_group(master->dev, NULL);
401 return -ENOMEM;
402 }
403
404 dev_dbg(master->dev, "binding %s (ops %ps)\n",
405 dev_name(component->dev), component->ops);
406
407 ret = component->ops->bind(component->dev, master->dev, data);
408 if (!ret) {
409 component->bound = true;
410
411 /*
412 * Close the component device's group so that resources
413 * allocated in the binding are encapsulated for removal
414 * at unbind. Remove the group on the DRM device as we
415 * can clean those resources up independently.
416 */
417 devres_close_group(component->dev, NULL);
418 devres_remove_group(master->dev, NULL);
419
420 dev_info(master->dev, "bound %s (ops %ps)\n",
421 dev_name(component->dev), component->ops);
422 } else {
423 devres_release_group(component->dev, NULL);
424 devres_release_group(master->dev, NULL);
425
426 dev_err(master->dev, "failed to bind %s (ops %ps): %d\n",
427 dev_name(component->dev), component->ops, ret);
428 }
429
430 return ret;
431}
432
433int component_bind_all(struct device *master_dev, void *data)
434{
435 struct master *master;
436 struct component *c;
437 int ret = 0;
438
439 WARN_ON(!mutex_is_locked(&component_mutex));
440
441 master = __master_find(master_dev, NULL);
442 if (!master)
443 return -EINVAL;
444
445 list_for_each_entry(c, &master->components, master_node) {
446 ret = component_bind(c, master, data);
447 if (ret)
448 break;
449 }
450
451 if (ret != 0) {
452 list_for_each_entry_continue_reverse(c, &master->components,
453 master_node)
454 component_unbind(c, master, data);
455 }
456
457 return ret;
458}
459EXPORT_SYMBOL_GPL(component_bind_all);
460
461int component_add(struct device *dev, const struct component_ops *ops)
462{
463 struct component *component;
464 int ret;
465
466 component = kzalloc(sizeof(*component), GFP_KERNEL);
467 if (!component)
468 return -ENOMEM;
469
470 component->ops = ops;
471 component->dev = dev;
472
473 dev_dbg(dev, "adding component (ops %ps)\n", ops);
474
475 mutex_lock(&component_mutex);
476 list_add_tail(&component->node, &component_list);
477
478 ret = try_to_bring_up_masters(component);
479 if (ret < 0) {
480 list_del(&component->node);
481
482 kfree(component);
483 }
484 mutex_unlock(&component_mutex);
485
486 return ret < 0 ? ret : 0;
487}
488EXPORT_SYMBOL_GPL(component_add);
489
490void component_del(struct device *dev, const struct component_ops *ops)
491{
492 struct component *c, *component = NULL;
493
494 mutex_lock(&component_mutex);
495 list_for_each_entry(c, &component_list, node)
496 if (c->dev == dev && c->ops == ops) {
497 list_del(&c->node);
498 component = c;
499 break;
500 }
501
502 if (component && component->master)
503 take_down_master(component->master);
504
505 mutex_unlock(&component_mutex);
506
507 WARN_ON(!component);
508 kfree(component);
509}
510EXPORT_SYMBOL_GPL(component_del);
511
512MODULE_LICENSE("GPL v2");