projects/linux·blob v5.0 · refs

595 lines · 13.3 KiB

1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Componentized device handling.
4 *
5 * This is work in progress. We gather up the component devices into a list,
6 * and bind them when instructed. At the moment, we're specific to the DRM
7 * subsystem, and only handles one master device, but this doesn't have to be
8 * the case.
9 */
10#include <linux/component.h>
11#include <linux/device.h>
12#include <linux/kref.h>
13#include <linux/list.h>
14#include <linux/module.h>
15#include <linux/mutex.h>
16#include <linux/slab.h>
17#include <linux/debugfs.h>
18
19struct component;
20
21struct component_match_array {
22 void *data;
23 int (*compare)(struct device *, void *);
24 void (*release)(struct device *, void *);
25 struct component *component;
26 bool duplicate;
27};
28
29struct component_match {
30 size_t alloc;
31 size_t num;
32 struct component_match_array *compare;
33};
34
35struct master {
36 struct list_head node;
37 bool bound;
38
39 const struct component_master_ops *ops;
40 struct device *dev;
41 struct component_match *match;
42 struct dentry *dentry;
43};
44
45struct component {
46 struct list_head node;
47 struct master *master;
48 bool bound;
49
50 const struct component_ops *ops;
51 struct device *dev;
52};
53
54static DEFINE_MUTEX(component_mutex);
55static LIST_HEAD(component_list);
56static LIST_HEAD(masters);
57
58#ifdef CONFIG_DEBUG_FS
59
60static struct dentry *component_debugfs_dir;
61
62static int component_devices_show(struct seq_file *s, void *data)
63{
64 struct master *m = s->private;
65 struct component_match *match = m->match;
66 size_t i;
67
68 mutex_lock(&component_mutex);
69 seq_printf(s, "%-40s %20s\n", "master name", "status");
70 seq_puts(s, "-------------------------------------------------------------\n");
71 seq_printf(s, "%-40s %20s\n\n",
72 dev_name(m->dev), m->bound ? "bound" : "not bound");
73
74 seq_printf(s, "%-40s %20s\n", "device name", "status");
75 seq_puts(s, "-------------------------------------------------------------\n");
76 for (i = 0; i < match->num; i++) {
77 struct device *d = (struct device *)match->compare[i].data;
78
79 seq_printf(s, "%-40s %20s\n", dev_name(d),
80 match->compare[i].component ?
81 "registered" : "not registered");
82 }
83 mutex_unlock(&component_mutex);
84
85 return 0;
86}
87
88DEFINE_SHOW_ATTRIBUTE(component_devices);
89
90static int __init component_debug_init(void)
91{
92 component_debugfs_dir = debugfs_create_dir("device_component", NULL);
93
94 return 0;
95}
96
97core_initcall(component_debug_init);
98
99static void component_master_debugfs_add(struct master *m)
100{
101 m->dentry = debugfs_create_file(dev_name(m->dev), 0444,
102 component_debugfs_dir,
103 m, &component_devices_fops);
104}
105
106static void component_master_debugfs_del(struct master *m)
107{
108 debugfs_remove(m->dentry);
109 m->dentry = NULL;
110}
111
112#else
113
114static void component_master_debugfs_add(struct master *m)
115{ }
116
117static void component_master_debugfs_del(struct master *m)
118{ }
119
120#endif
121
122static struct master *__master_find(struct device *dev,
123 const struct component_master_ops *ops)
124{
125 struct master *m;
126
127 list_for_each_entry(m, &masters, node)
128 if (m->dev == dev && (!ops || m->ops == ops))
129 return m;
130
131 return NULL;
132}
133
134static struct component *find_component(struct master *master,
135 int (*compare)(struct device *, void *), void *compare_data)
136{
137 struct component *c;
138
139 list_for_each_entry(c, &component_list, node) {
140 if (c->master && c->master != master)
141 continue;
142
143 if (compare(c->dev, compare_data))
144 return c;
145 }
146
147 return NULL;
148}
149
150static int find_components(struct master *master)
151{
152 struct component_match *match = master->match;
153 size_t i;
154 int ret = 0;
155
156 /*
157 * Scan the array of match functions and attach
158 * any components which are found to this master.
159 */
160 for (i = 0; i < match->num; i++) {
161 struct component_match_array *mc = &match->compare[i];
162 struct component *c;
163
164 dev_dbg(master->dev, "Looking for component %zu\n", i);
165
166 if (match->compare[i].component)
167 continue;
168
169 c = find_component(master, mc->compare, mc->data);
170 if (!c) {
171 ret = -ENXIO;
172 break;
173 }
174
175 dev_dbg(master->dev, "found component %s, duplicate %u\n", dev_name(c->dev), !!c->master);
176
177 /* Attach this component to the master */
178 match->compare[i].duplicate = !!c->master;
179 match->compare[i].component = c;
180 c->master = master;
181 }
182 return ret;
183}
184
185/* Detach component from associated master */
186static void remove_component(struct master *master, struct component *c)
187{
188 size_t i;
189
190 /* Detach the component from this master. */
191 for (i = 0; i < master->match->num; i++)
192 if (master->match->compare[i].component == c)
193 master->match->compare[i].component = NULL;
194}
195
196/*
197 * Try to bring up a master. If component is NULL, we're interested in
198 * this master, otherwise it's a component which must be present to try
199 * and bring up the master.
200 *
201 * Returns 1 for successful bringup, 0 if not ready, or -ve errno.
202 */
203static int try_to_bring_up_master(struct master *master,
204 struct component *component)
205{
206 int ret;
207
208 dev_dbg(master->dev, "trying to bring up master\n");
209
210 if (find_components(master)) {
211 dev_dbg(master->dev, "master has incomplete components\n");
212 return 0;
213 }
214
215 if (component && component->master != master) {
216 dev_dbg(master->dev, "master is not for this component (%s)\n",
217 dev_name(component->dev));
218 return 0;
219 }
220
221 if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
222 return -ENOMEM;
223
224 /* Found all components */
225 ret = master->ops->bind(master->dev);
226 if (ret < 0) {
227 devres_release_group(master->dev, NULL);
228 dev_info(master->dev, "master bind failed: %d\n", ret);
229 return ret;
230 }
231
232 master->bound = true;
233 return 1;
234}
235
236static int try_to_bring_up_masters(struct component *component)
237{
238 struct master *m;
239 int ret = 0;
240
241 list_for_each_entry(m, &masters, node) {
242 if (!m->bound) {
243 ret = try_to_bring_up_master(m, component);
244 if (ret != 0)
245 break;
246 }
247 }
248
249 return ret;
250}
251
252static void take_down_master(struct master *master)
253{
254 if (master->bound) {
255 master->ops->unbind(master->dev);
256 devres_release_group(master->dev, NULL);
257 master->bound = false;
258 }
259}
260
261static void component_match_release(struct device *master,
262 struct component_match *match)
263{
264 unsigned int i;
265
266 for (i = 0; i < match->num; i++) {
267 struct component_match_array *mc = &match->compare[i];
268
269 if (mc->release)
270 mc->release(master, mc->data);
271 }
272
273 kfree(match->compare);
274}
275
276static void devm_component_match_release(struct device *dev, void *res)
277{
278 component_match_release(dev, res);
279}
280
281static int component_match_realloc(struct device *dev,
282 struct component_match *match, size_t num)
283{
284 struct component_match_array *new;
285
286 if (match->alloc == num)
287 return 0;
288
289 new = kmalloc_array(num, sizeof(*new), GFP_KERNEL);
290 if (!new)
291 return -ENOMEM;
292
293 if (match->compare) {
294 memcpy(new, match->compare, sizeof(*new) *
295 min(match->num, num));
296 kfree(match->compare);
297 }
298 match->compare = new;
299 match->alloc = num;
300
301 return 0;
302}
303
304/*
305 * Add a component to be matched, with a release function.
306 *
307 * The match array is first created or extended if necessary.
308 */
309void component_match_add_release(struct device *master,
310 struct component_match **matchptr,
311 void (*release)(struct device *, void *),
312 int (*compare)(struct device *, void *), void *compare_data)
313{
314 struct component_match *match = *matchptr;
315
316 if (IS_ERR(match))
317 return;
318
319 if (!match) {
320 match = devres_alloc(devm_component_match_release,
321 sizeof(*match), GFP_KERNEL);
322 if (!match) {
323 *matchptr = ERR_PTR(-ENOMEM);
324 return;
325 }
326
327 devres_add(master, match);
328
329 *matchptr = match;
330 }
331
332 if (match->num == match->alloc) {
333 size_t new_size = match->alloc + 16;
334 int ret;
335
336 ret = component_match_realloc(master, match, new_size);
337 if (ret) {
338 *matchptr = ERR_PTR(ret);
339 return;
340 }
341 }
342
343 match->compare[match->num].compare = compare;
344 match->compare[match->num].release = release;
345 match->compare[match->num].data = compare_data;
346 match->compare[match->num].component = NULL;
347 match->num++;
348}
349EXPORT_SYMBOL(component_match_add_release);
350
351static void free_master(struct master *master)
352{
353 struct component_match *match = master->match;
354 int i;
355
356 component_master_debugfs_del(master);
357 list_del(&master->node);
358
359 if (match) {
360 for (i = 0; i < match->num; i++) {
361 struct component *c = match->compare[i].component;
362 if (c)
363 c->master = NULL;
364 }
365 }
366
367 kfree(master);
368}
369
370int component_master_add_with_match(struct device *dev,
371 const struct component_master_ops *ops,
372 struct component_match *match)
373{
374 struct master *master;
375 int ret;
376
377 /* Reallocate the match array for its true size */
378 ret = component_match_realloc(dev, match, match->num);
379 if (ret)
380 return ret;
381
382 master = kzalloc(sizeof(*master), GFP_KERNEL);
383 if (!master)
384 return -ENOMEM;
385
386 master->dev = dev;
387 master->ops = ops;
388 master->match = match;
389
390 component_master_debugfs_add(master);
391 /* Add to the list of available masters. */
392 mutex_lock(&component_mutex);
393 list_add(&master->node, &masters);
394
395 ret = try_to_bring_up_master(master, NULL);
396
397 if (ret < 0)
398 free_master(master);
399
400 mutex_unlock(&component_mutex);
401
402 return ret < 0 ? ret : 0;
403}
404EXPORT_SYMBOL_GPL(component_master_add_with_match);
405
406void component_master_del(struct device *dev,
407 const struct component_master_ops *ops)
408{
409 struct master *master;
410
411 mutex_lock(&component_mutex);
412 master = __master_find(dev, ops);
413 if (master) {
414 take_down_master(master);
415 free_master(master);
416 }
417 mutex_unlock(&component_mutex);
418}
419EXPORT_SYMBOL_GPL(component_master_del);
420
421static void component_unbind(struct component *component,
422 struct master *master, void *data)
423{
424 WARN_ON(!component->bound);
425
426 component->ops->unbind(component->dev, master->dev, data);
427 component->bound = false;
428
429 /* Release all resources claimed in the binding of this component */
430 devres_release_group(component->dev, component);
431}
432
433void component_unbind_all(struct device *master_dev, void *data)
434{
435 struct master *master;
436 struct component *c;
437 size_t i;
438
439 WARN_ON(!mutex_is_locked(&component_mutex));
440
441 master = __master_find(master_dev, NULL);
442 if (!master)
443 return;
444
445 /* Unbind components in reverse order */
446 for (i = master->match->num; i--; )
447 if (!master->match->compare[i].duplicate) {
448 c = master->match->compare[i].component;
449 component_unbind(c, master, data);
450 }
451}
452EXPORT_SYMBOL_GPL(component_unbind_all);
453
454static int component_bind(struct component *component, struct master *master,
455 void *data)
456{
457 int ret;
458
459 /*
460 * Each component initialises inside its own devres group.
461 * This allows us to roll-back a failed component without
462 * affecting anything else.
463 */
464 if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
465 return -ENOMEM;
466
467 /*
468 * Also open a group for the device itself: this allows us
469 * to release the resources claimed against the sub-device
470 * at the appropriate moment.
471 */
472 if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
473 devres_release_group(master->dev, NULL);
474 return -ENOMEM;
475 }
476
477 dev_dbg(master->dev, "binding %s (ops %ps)\n",
478 dev_name(component->dev), component->ops);
479
480 ret = component->ops->bind(component->dev, master->dev, data);
481 if (!ret) {
482 component->bound = true;
483
484 /*
485 * Close the component device's group so that resources
486 * allocated in the binding are encapsulated for removal
487 * at unbind. Remove the group on the DRM device as we
488 * can clean those resources up independently.
489 */
490 devres_close_group(component->dev, NULL);
491 devres_remove_group(master->dev, NULL);
492
493 dev_info(master->dev, "bound %s (ops %ps)\n",
494 dev_name(component->dev), component->ops);
495 } else {
496 devres_release_group(component->dev, NULL);
497 devres_release_group(master->dev, NULL);
498
499 dev_err(master->dev, "failed to bind %s (ops %ps): %d\n",
500 dev_name(component->dev), component->ops, ret);
501 }
502
503 return ret;
504}
505
506int component_bind_all(struct device *master_dev, void *data)
507{
508 struct master *master;
509 struct component *c;
510 size_t i;
511 int ret = 0;
512
513 WARN_ON(!mutex_is_locked(&component_mutex));
514
515 master = __master_find(master_dev, NULL);
516 if (!master)
517 return -EINVAL;
518
519 /* Bind components in match order */
520 for (i = 0; i < master->match->num; i++)
521 if (!master->match->compare[i].duplicate) {
522 c = master->match->compare[i].component;
523 ret = component_bind(c, master, data);
524 if (ret)
525 break;
526 }
527
528 if (ret != 0) {
529 for (; i > 0; i--)
530 if (!master->match->compare[i - 1].duplicate) {
531 c = master->match->compare[i - 1].component;
532 component_unbind(c, master, data);
533 }
534 }
535
536 return ret;
537}
538EXPORT_SYMBOL_GPL(component_bind_all);
539
540int component_add(struct device *dev, const struct component_ops *ops)
541{
542 struct component *component;
543 int ret;
544
545 component = kzalloc(sizeof(*component), GFP_KERNEL);
546 if (!component)
547 return -ENOMEM;
548
549 component->ops = ops;
550 component->dev = dev;
551
552 dev_dbg(dev, "adding component (ops %ps)\n", ops);
553
554 mutex_lock(&component_mutex);
555 list_add_tail(&component->node, &component_list);
556
557 ret = try_to_bring_up_masters(component);
558 if (ret < 0) {
559 if (component->master)
560 remove_component(component->master, component);
561 list_del(&component->node);
562
563 kfree(component);
564 }
565 mutex_unlock(&component_mutex);
566
567 return ret < 0 ? ret : 0;
568}
569EXPORT_SYMBOL_GPL(component_add);
570
571void component_del(struct device *dev, const struct component_ops *ops)
572{
573 struct component *c, *component = NULL;
574
575 mutex_lock(&component_mutex);
576 list_for_each_entry(c, &component_list, node)
577 if (c->dev == dev && c->ops == ops) {
578 list_del(&c->node);
579 component = c;
580 break;
581 }
582
583 if (component && component->master) {
584 take_down_master(component->master);
585 remove_component(component->master, component);
586 }
587
588 mutex_unlock(&component_mutex);
589
590 WARN_ON(!component);
591 kfree(component);
592}
593EXPORT_SYMBOL_GPL(component_del);
594
595MODULE_LICENSE("GPL v2");