projects/linux·blob v5.13 · refs

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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/mutex.h>
15#include <linux/slab.h>
16#include <linux/debugfs.h>
17
18/**
19 * DOC: overview
20 *
21 * The component helper allows drivers to collect a pile of sub-devices,
22 * including their bound drivers, into an aggregate driver. Various subsystems
23 * already provide functions to get hold of such components, e.g.
24 * of_clk_get_by_name(). The component helper can be used when such a
25 * subsystem-specific way to find a device is not available: The component
26 * helper fills the niche of aggregate drivers for specific hardware, where
27 * further standardization into a subsystem would not be practical. The common
28 * example is when a logical device (e.g. a DRM display driver) is spread around
29 * the SoC on various components (scanout engines, blending blocks, transcoders
30 * for various outputs and so on).
31 *
32 * The component helper also doesn't solve runtime dependencies, e.g. for system
33 * suspend and resume operations. See also :ref:`device links<device_link>`.
34 *
35 * Components are registered using component_add() and unregistered with
36 * component_del(), usually from the driver's probe and disconnect functions.
37 *
38 * Aggregate drivers first assemble a component match list of what they need
39 * using component_match_add(). This is then registered as an aggregate driver
40 * using component_master_add_with_match(), and unregistered using
41 * component_master_del().
42 */
43
44struct component;
45
46struct component_match_array {
47 void *data;
48 int (*compare)(struct device *, void *);
49 int (*compare_typed)(struct device *, int, void *);
50 void (*release)(struct device *, void *);
51 struct component *component;
52 bool duplicate;
53};
54
55struct component_match {
56 size_t alloc;
57 size_t num;
58 struct component_match_array *compare;
59};
60
61struct master {
62 struct list_head node;
63 bool bound;
64
65 const struct component_master_ops *ops;
66 struct device *dev;
67 struct component_match *match;
68};
69
70struct component {
71 struct list_head node;
72 struct master *master;
73 bool bound;
74
75 const struct component_ops *ops;
76 int subcomponent;
77 struct device *dev;
78};
79
80static DEFINE_MUTEX(component_mutex);
81static LIST_HEAD(component_list);
82static LIST_HEAD(masters);
83
84#ifdef CONFIG_DEBUG_FS
85
86static struct dentry *component_debugfs_dir;
87
88static int component_devices_show(struct seq_file *s, void *data)
89{
90 struct master *m = s->private;
91 struct component_match *match = m->match;
92 size_t i;
93
94 mutex_lock(&component_mutex);
95 seq_printf(s, "%-40s %20s\n", "master name", "status");
96 seq_puts(s, "-------------------------------------------------------------\n");
97 seq_printf(s, "%-40s %20s\n\n",
98 dev_name(m->dev), m->bound ? "bound" : "not bound");
99
100 seq_printf(s, "%-40s %20s\n", "device name", "status");
101 seq_puts(s, "-------------------------------------------------------------\n");
102 for (i = 0; i < match->num; i++) {
103 struct component *component = match->compare[i].component;
104
105 seq_printf(s, "%-40s %20s\n",
106 component ? dev_name(component->dev) : "(unknown)",
107 component ? (component->bound ? "bound" : "not bound") : "not registered");
108 }
109 mutex_unlock(&component_mutex);
110
111 return 0;
112}
113
114DEFINE_SHOW_ATTRIBUTE(component_devices);
115
116static int __init component_debug_init(void)
117{
118 component_debugfs_dir = debugfs_create_dir("device_component", NULL);
119
120 return 0;
121}
122
123core_initcall(component_debug_init);
124
125static void component_master_debugfs_add(struct master *m)
126{
127 debugfs_create_file(dev_name(m->dev), 0444, component_debugfs_dir, m,
128 &component_devices_fops);
129}
130
131static void component_master_debugfs_del(struct master *m)
132{
133 debugfs_remove(debugfs_lookup(dev_name(m->dev), component_debugfs_dir));
134}
135
136#else
137
138static void component_master_debugfs_add(struct master *m)
139{ }
140
141static void component_master_debugfs_del(struct master *m)
142{ }
143
144#endif
145
146static struct master *__master_find(struct device *dev,
147 const struct component_master_ops *ops)
148{
149 struct master *m;
150
151 list_for_each_entry(m, &masters, node)
152 if (m->dev == dev && (!ops || m->ops == ops))
153 return m;
154
155 return NULL;
156}
157
158static struct component *find_component(struct master *master,
159 struct component_match_array *mc)
160{
161 struct component *c;
162
163 list_for_each_entry(c, &component_list, node) {
164 if (c->master && c->master != master)
165 continue;
166
167 if (mc->compare && mc->compare(c->dev, mc->data))
168 return c;
169
170 if (mc->compare_typed &&
171 mc->compare_typed(c->dev, c->subcomponent, mc->data))
172 return c;
173 }
174
175 return NULL;
176}
177
178static int find_components(struct master *master)
179{
180 struct component_match *match = master->match;
181 size_t i;
182 int ret = 0;
183
184 /*
185 * Scan the array of match functions and attach
186 * any components which are found to this master.
187 */
188 for (i = 0; i < match->num; i++) {
189 struct component_match_array *mc = &match->compare[i];
190 struct component *c;
191
192 dev_dbg(master->dev, "Looking for component %zu\n", i);
193
194 if (match->compare[i].component)
195 continue;
196
197 c = find_component(master, mc);
198 if (!c) {
199 ret = -ENXIO;
200 break;
201 }
202
203 dev_dbg(master->dev, "found component %s, duplicate %u\n", dev_name(c->dev), !!c->master);
204
205 /* Attach this component to the master */
206 match->compare[i].duplicate = !!c->master;
207 match->compare[i].component = c;
208 c->master = master;
209 }
210 return ret;
211}
212
213/* Detach component from associated master */
214static void remove_component(struct master *master, struct component *c)
215{
216 size_t i;
217
218 /* Detach the component from this master. */
219 for (i = 0; i < master->match->num; i++)
220 if (master->match->compare[i].component == c)
221 master->match->compare[i].component = NULL;
222}
223
224/*
225 * Try to bring up a master. If component is NULL, we're interested in
226 * this master, otherwise it's a component which must be present to try
227 * and bring up the master.
228 *
229 * Returns 1 for successful bringup, 0 if not ready, or -ve errno.
230 */
231static int try_to_bring_up_master(struct master *master,
232 struct component *component)
233{
234 int ret;
235
236 dev_dbg(master->dev, "trying to bring up master\n");
237
238 if (find_components(master)) {
239 dev_dbg(master->dev, "master has incomplete components\n");
240 return 0;
241 }
242
243 if (component && component->master != master) {
244 dev_dbg(master->dev, "master is not for this component (%s)\n",
245 dev_name(component->dev));
246 return 0;
247 }
248
249 if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
250 return -ENOMEM;
251
252 /* Found all components */
253 ret = master->ops->bind(master->dev);
254 if (ret < 0) {
255 devres_release_group(master->dev, NULL);
256 if (ret != -EPROBE_DEFER)
257 dev_info(master->dev, "master bind failed: %d\n", ret);
258 return ret;
259 }
260
261 master->bound = true;
262 return 1;
263}
264
265static int try_to_bring_up_masters(struct component *component)
266{
267 struct master *m;
268 int ret = 0;
269
270 list_for_each_entry(m, &masters, node) {
271 if (!m->bound) {
272 ret = try_to_bring_up_master(m, component);
273 if (ret != 0)
274 break;
275 }
276 }
277
278 return ret;
279}
280
281static void take_down_master(struct master *master)
282{
283 if (master->bound) {
284 master->ops->unbind(master->dev);
285 devres_release_group(master->dev, NULL);
286 master->bound = false;
287 }
288}
289
290static void component_match_release(struct device *master,
291 struct component_match *match)
292{
293 unsigned int i;
294
295 for (i = 0; i < match->num; i++) {
296 struct component_match_array *mc = &match->compare[i];
297
298 if (mc->release)
299 mc->release(master, mc->data);
300 }
301
302 kfree(match->compare);
303}
304
305static void devm_component_match_release(struct device *dev, void *res)
306{
307 component_match_release(dev, res);
308}
309
310static int component_match_realloc(struct device *dev,
311 struct component_match *match, size_t num)
312{
313 struct component_match_array *new;
314
315 if (match->alloc == num)
316 return 0;
317
318 new = kmalloc_array(num, sizeof(*new), GFP_KERNEL);
319 if (!new)
320 return -ENOMEM;
321
322 if (match->compare) {
323 memcpy(new, match->compare, sizeof(*new) *
324 min(match->num, num));
325 kfree(match->compare);
326 }
327 match->compare = new;
328 match->alloc = num;
329
330 return 0;
331}
332
333static void __component_match_add(struct device *master,
334 struct component_match **matchptr,
335 void (*release)(struct device *, void *),
336 int (*compare)(struct device *, void *),
337 int (*compare_typed)(struct device *, int, void *),
338 void *compare_data)
339{
340 struct component_match *match = *matchptr;
341
342 if (IS_ERR(match))
343 return;
344
345 if (!match) {
346 match = devres_alloc(devm_component_match_release,
347 sizeof(*match), GFP_KERNEL);
348 if (!match) {
349 *matchptr = ERR_PTR(-ENOMEM);
350 return;
351 }
352
353 devres_add(master, match);
354
355 *matchptr = match;
356 }
357
358 if (match->num == match->alloc) {
359 size_t new_size = match->alloc + 16;
360 int ret;
361
362 ret = component_match_realloc(master, match, new_size);
363 if (ret) {
364 *matchptr = ERR_PTR(ret);
365 return;
366 }
367 }
368
369 match->compare[match->num].compare = compare;
370 match->compare[match->num].compare_typed = compare_typed;
371 match->compare[match->num].release = release;
372 match->compare[match->num].data = compare_data;
373 match->compare[match->num].component = NULL;
374 match->num++;
375}
376
377/**
378 * component_match_add_release - add a component match entry with release callback
379 * @master: device with the aggregate driver
380 * @matchptr: pointer to the list of component matches
381 * @release: release function for @compare_data
382 * @compare: compare function to match against all components
383 * @compare_data: opaque pointer passed to the @compare function
384 *
385 * Adds a new component match to the list stored in @matchptr, which the @master
386 * aggregate driver needs to function. The list of component matches pointed to
387 * by @matchptr must be initialized to NULL before adding the first match. This
388 * only matches against components added with component_add().
389 *
390 * The allocated match list in @matchptr is automatically released using devm
391 * actions, where upon @release will be called to free any references held by
392 * @compare_data, e.g. when @compare_data is a &device_node that must be
393 * released with of_node_put().
394 *
395 * See also component_match_add() and component_match_add_typed().
396 */
397void component_match_add_release(struct device *master,
398 struct component_match **matchptr,
399 void (*release)(struct device *, void *),
400 int (*compare)(struct device *, void *), void *compare_data)
401{
402 __component_match_add(master, matchptr, release, compare, NULL,
403 compare_data);
404}
405EXPORT_SYMBOL(component_match_add_release);
406
407/**
408 * component_match_add_typed - add a component match entry for a typed component
409 * @master: device with the aggregate driver
410 * @matchptr: pointer to the list of component matches
411 * @compare_typed: compare function to match against all typed components
412 * @compare_data: opaque pointer passed to the @compare function
413 *
414 * Adds a new component match to the list stored in @matchptr, which the @master
415 * aggregate driver needs to function. The list of component matches pointed to
416 * by @matchptr must be initialized to NULL before adding the first match. This
417 * only matches against components added with component_add_typed().
418 *
419 * The allocated match list in @matchptr is automatically released using devm
420 * actions.
421 *
422 * See also component_match_add_release() and component_match_add_typed().
423 */
424void component_match_add_typed(struct device *master,
425 struct component_match **matchptr,
426 int (*compare_typed)(struct device *, int, void *), void *compare_data)
427{
428 __component_match_add(master, matchptr, NULL, NULL, compare_typed,
429 compare_data);
430}
431EXPORT_SYMBOL(component_match_add_typed);
432
433static void free_master(struct master *master)
434{
435 struct component_match *match = master->match;
436 int i;
437
438 component_master_debugfs_del(master);
439 list_del(&master->node);
440
441 if (match) {
442 for (i = 0; i < match->num; i++) {
443 struct component *c = match->compare[i].component;
444 if (c)
445 c->master = NULL;
446 }
447 }
448
449 kfree(master);
450}
451
452/**
453 * component_master_add_with_match - register an aggregate driver
454 * @dev: device with the aggregate driver
455 * @ops: callbacks for the aggregate driver
456 * @match: component match list for the aggregate driver
457 *
458 * Registers a new aggregate driver consisting of the components added to @match
459 * by calling one of the component_match_add() functions. Once all components in
460 * @match are available, it will be assembled by calling
461 * &component_master_ops.bind from @ops. Must be unregistered by calling
462 * component_master_del().
463 */
464int component_master_add_with_match(struct device *dev,
465 const struct component_master_ops *ops,
466 struct component_match *match)
467{
468 struct master *master;
469 int ret;
470
471 /* Reallocate the match array for its true size */
472 ret = component_match_realloc(dev, match, match->num);
473 if (ret)
474 return ret;
475
476 master = kzalloc(sizeof(*master), GFP_KERNEL);
477 if (!master)
478 return -ENOMEM;
479
480 master->dev = dev;
481 master->ops = ops;
482 master->match = match;
483
484 component_master_debugfs_add(master);
485 /* Add to the list of available masters. */
486 mutex_lock(&component_mutex);
487 list_add(&master->node, &masters);
488
489 ret = try_to_bring_up_master(master, NULL);
490
491 if (ret < 0)
492 free_master(master);
493
494 mutex_unlock(&component_mutex);
495
496 return ret < 0 ? ret : 0;
497}
498EXPORT_SYMBOL_GPL(component_master_add_with_match);
499
500/**
501 * component_master_del - unregister an aggregate driver
502 * @dev: device with the aggregate driver
503 * @ops: callbacks for the aggregate driver
504 *
505 * Unregisters an aggregate driver registered with
506 * component_master_add_with_match(). If necessary the aggregate driver is first
507 * disassembled by calling &component_master_ops.unbind from @ops.
508 */
509void component_master_del(struct device *dev,
510 const struct component_master_ops *ops)
511{
512 struct master *master;
513
514 mutex_lock(&component_mutex);
515 master = __master_find(dev, ops);
516 if (master) {
517 take_down_master(master);
518 free_master(master);
519 }
520 mutex_unlock(&component_mutex);
521}
522EXPORT_SYMBOL_GPL(component_master_del);
523
524static void component_unbind(struct component *component,
525 struct master *master, void *data)
526{
527 WARN_ON(!component->bound);
528
529 if (component->ops && component->ops->unbind)
530 component->ops->unbind(component->dev, master->dev, data);
531 component->bound = false;
532
533 /* Release all resources claimed in the binding of this component */
534 devres_release_group(component->dev, component);
535}
536
537/**
538 * component_unbind_all - unbind all components of an aggregate driver
539 * @master_dev: device with the aggregate driver
540 * @data: opaque pointer, passed to all components
541 *
542 * Unbinds all components of the aggregate @dev by passing @data to their
543 * &component_ops.unbind functions. Should be called from
544 * &component_master_ops.unbind.
545 */
546void component_unbind_all(struct device *master_dev, void *data)
547{
548 struct master *master;
549 struct component *c;
550 size_t i;
551
552 WARN_ON(!mutex_is_locked(&component_mutex));
553
554 master = __master_find(master_dev, NULL);
555 if (!master)
556 return;
557
558 /* Unbind components in reverse order */
559 for (i = master->match->num; i--; )
560 if (!master->match->compare[i].duplicate) {
561 c = master->match->compare[i].component;
562 component_unbind(c, master, data);
563 }
564}
565EXPORT_SYMBOL_GPL(component_unbind_all);
566
567static int component_bind(struct component *component, struct master *master,
568 void *data)
569{
570 int ret;
571
572 /*
573 * Each component initialises inside its own devres group.
574 * This allows us to roll-back a failed component without
575 * affecting anything else.
576 */
577 if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
578 return -ENOMEM;
579
580 /*
581 * Also open a group for the device itself: this allows us
582 * to release the resources claimed against the sub-device
583 * at the appropriate moment.
584 */
585 if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
586 devres_release_group(master->dev, NULL);
587 return -ENOMEM;
588 }
589
590 dev_dbg(master->dev, "binding %s (ops %ps)\n",
591 dev_name(component->dev), component->ops);
592
593 ret = component->ops->bind(component->dev, master->dev, data);
594 if (!ret) {
595 component->bound = true;
596
597 /*
598 * Close the component device's group so that resources
599 * allocated in the binding are encapsulated for removal
600 * at unbind. Remove the group on the DRM device as we
601 * can clean those resources up independently.
602 */
603 devres_close_group(component->dev, NULL);
604 devres_remove_group(master->dev, NULL);
605
606 dev_info(master->dev, "bound %s (ops %ps)\n",
607 dev_name(component->dev), component->ops);
608 } else {
609 devres_release_group(component->dev, NULL);
610 devres_release_group(master->dev, NULL);
611
612 if (ret != -EPROBE_DEFER)
613 dev_err(master->dev, "failed to bind %s (ops %ps): %d\n",
614 dev_name(component->dev), component->ops, ret);
615 }
616
617 return ret;
618}
619
620/**
621 * component_bind_all - bind all components of an aggregate driver
622 * @master_dev: device with the aggregate driver
623 * @data: opaque pointer, passed to all components
624 *
625 * Binds all components of the aggregate @dev by passing @data to their
626 * &component_ops.bind functions. Should be called from
627 * &component_master_ops.bind.
628 */
629int component_bind_all(struct device *master_dev, void *data)
630{
631 struct master *master;
632 struct component *c;
633 size_t i;
634 int ret = 0;
635
636 WARN_ON(!mutex_is_locked(&component_mutex));
637
638 master = __master_find(master_dev, NULL);
639 if (!master)
640 return -EINVAL;
641
642 /* Bind components in match order */
643 for (i = 0; i < master->match->num; i++)
644 if (!master->match->compare[i].duplicate) {
645 c = master->match->compare[i].component;
646 ret = component_bind(c, master, data);
647 if (ret)
648 break;
649 }
650
651 if (ret != 0) {
652 for (; i > 0; i--)
653 if (!master->match->compare[i - 1].duplicate) {
654 c = master->match->compare[i - 1].component;
655 component_unbind(c, master, data);
656 }
657 }
658
659 return ret;
660}
661EXPORT_SYMBOL_GPL(component_bind_all);
662
663static int __component_add(struct device *dev, const struct component_ops *ops,
664 int subcomponent)
665{
666 struct component *component;
667 int ret;
668
669 component = kzalloc(sizeof(*component), GFP_KERNEL);
670 if (!component)
671 return -ENOMEM;
672
673 component->ops = ops;
674 component->dev = dev;
675 component->subcomponent = subcomponent;
676
677 dev_dbg(dev, "adding component (ops %ps)\n", ops);
678
679 mutex_lock(&component_mutex);
680 list_add_tail(&component->node, &component_list);
681
682 ret = try_to_bring_up_masters(component);
683 if (ret < 0) {
684 if (component->master)
685 remove_component(component->master, component);
686 list_del(&component->node);
687
688 kfree(component);
689 }
690 mutex_unlock(&component_mutex);
691
692 return ret < 0 ? ret : 0;
693}
694
695/**
696 * component_add_typed - register a component
697 * @dev: component device
698 * @ops: component callbacks
699 * @subcomponent: nonzero identifier for subcomponents
700 *
701 * Register a new component for @dev. Functions in @ops will be call when the
702 * aggregate driver is ready to bind the overall driver by calling
703 * component_bind_all(). See also &struct component_ops.
704 *
705 * @subcomponent must be nonzero and is used to differentiate between multiple
706 * components registerd on the same device @dev. These components are match
707 * using component_match_add_typed().
708 *
709 * The component needs to be unregistered at driver unload/disconnect by
710 * calling component_del().
711 *
712 * See also component_add().
713 */
714int component_add_typed(struct device *dev, const struct component_ops *ops,
715 int subcomponent)
716{
717 if (WARN_ON(subcomponent == 0))
718 return -EINVAL;
719
720 return __component_add(dev, ops, subcomponent);
721}
722EXPORT_SYMBOL_GPL(component_add_typed);
723
724/**
725 * component_add - register a component
726 * @dev: component device
727 * @ops: component callbacks
728 *
729 * Register a new component for @dev. Functions in @ops will be called when the
730 * aggregate driver is ready to bind the overall driver by calling
731 * component_bind_all(). See also &struct component_ops.
732 *
733 * The component needs to be unregistered at driver unload/disconnect by
734 * calling component_del().
735 *
736 * See also component_add_typed() for a variant that allows multipled different
737 * components on the same device.
738 */
739int component_add(struct device *dev, const struct component_ops *ops)
740{
741 return __component_add(dev, ops, 0);
742}
743EXPORT_SYMBOL_GPL(component_add);
744
745/**
746 * component_del - unregister a component
747 * @dev: component device
748 * @ops: component callbacks
749 *
750 * Unregister a component added with component_add(). If the component is bound
751 * into an aggregate driver, this will force the entire aggregate driver, including
752 * all its components, to be unbound.
753 */
754void component_del(struct device *dev, const struct component_ops *ops)
755{
756 struct component *c, *component = NULL;
757
758 mutex_lock(&component_mutex);
759 list_for_each_entry(c, &component_list, node)
760 if (c->dev == dev && c->ops == ops) {
761 list_del(&c->node);
762 component = c;
763 break;
764 }
765
766 if (component && component->master) {
767 take_down_master(component->master);
768 remove_component(component->master, component);
769 }
770
771 mutex_unlock(&component_mutex);
772
773 WARN_ON(!component);
774 kfree(component);
775}
776EXPORT_SYMBOL_GPL(component_del);