projects/linux·blob v5.8 · 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 struct dentry *dentry;
69};
70
71struct component {
72 struct list_head node;
73 struct master *master;
74 bool bound;
75
76 const struct component_ops *ops;
77 int subcomponent;
78 struct device *dev;
79};
80
81static DEFINE_MUTEX(component_mutex);
82static LIST_HEAD(component_list);
83static LIST_HEAD(masters);
84
85#ifdef CONFIG_DEBUG_FS
86
87static struct dentry *component_debugfs_dir;
88
89static int component_devices_show(struct seq_file *s, void *data)
90{
91 struct master *m = s->private;
92 struct component_match *match = m->match;
93 size_t i;
94
95 mutex_lock(&component_mutex);
96 seq_printf(s, "%-40s %20s\n", "master name", "status");
97 seq_puts(s, "-------------------------------------------------------------\n");
98 seq_printf(s, "%-40s %20s\n\n",
99 dev_name(m->dev), m->bound ? "bound" : "not bound");
100
101 seq_printf(s, "%-40s %20s\n", "device name", "status");
102 seq_puts(s, "-------------------------------------------------------------\n");
103 for (i = 0; i < match->num; i++) {
104 struct component *component = match->compare[i].component;
105
106 seq_printf(s, "%-40s %20s\n",
107 component ? dev_name(component->dev) : "(unknown)",
108 component ? (component->bound ? "bound" : "not bound") : "not registered");
109 }
110 mutex_unlock(&component_mutex);
111
112 return 0;
113}
114
115DEFINE_SHOW_ATTRIBUTE(component_devices);
116
117static int __init component_debug_init(void)
118{
119 component_debugfs_dir = debugfs_create_dir("device_component", NULL);
120
121 return 0;
122}
123
124core_initcall(component_debug_init);
125
126static void component_master_debugfs_add(struct master *m)
127{
128 m->dentry = debugfs_create_file(dev_name(m->dev), 0444,
129 component_debugfs_dir,
130 m, &component_devices_fops);
131}
132
133static void component_master_debugfs_del(struct master *m)
134{
135 debugfs_remove(m->dentry);
136 m->dentry = NULL;
137}
138
139#else
140
141static void component_master_debugfs_add(struct master *m)
142{ }
143
144static void component_master_debugfs_del(struct master *m)
145{ }
146
147#endif
148
149static struct master *__master_find(struct device *dev,
150 const struct component_master_ops *ops)
151{
152 struct master *m;
153
154 list_for_each_entry(m, &masters, node)
155 if (m->dev == dev && (!ops || m->ops == ops))
156 return m;
157
158 return NULL;
159}
160
161static struct component *find_component(struct master *master,
162 struct component_match_array *mc)
163{
164 struct component *c;
165
166 list_for_each_entry(c, &component_list, node) {
167 if (c->master && c->master != master)
168 continue;
169
170 if (mc->compare && mc->compare(c->dev, mc->data))
171 return c;
172
173 if (mc->compare_typed &&
174 mc->compare_typed(c->dev, c->subcomponent, mc->data))
175 return c;
176 }
177
178 return NULL;
179}
180
181static int find_components(struct master *master)
182{
183 struct component_match *match = master->match;
184 size_t i;
185 int ret = 0;
186
187 /*
188 * Scan the array of match functions and attach
189 * any components which are found to this master.
190 */
191 for (i = 0; i < match->num; i++) {
192 struct component_match_array *mc = &match->compare[i];
193 struct component *c;
194
195 dev_dbg(master->dev, "Looking for component %zu\n", i);
196
197 if (match->compare[i].component)
198 continue;
199
200 c = find_component(master, mc);
201 if (!c) {
202 ret = -ENXIO;
203 break;
204 }
205
206 dev_dbg(master->dev, "found component %s, duplicate %u\n", dev_name(c->dev), !!c->master);
207
208 /* Attach this component to the master */
209 match->compare[i].duplicate = !!c->master;
210 match->compare[i].component = c;
211 c->master = master;
212 }
213 return ret;
214}
215
216/* Detach component from associated master */
217static void remove_component(struct master *master, struct component *c)
218{
219 size_t i;
220
221 /* Detach the component from this master. */
222 for (i = 0; i < master->match->num; i++)
223 if (master->match->compare[i].component == c)
224 master->match->compare[i].component = NULL;
225}
226
227/*
228 * Try to bring up a master. If component is NULL, we're interested in
229 * this master, otherwise it's a component which must be present to try
230 * and bring up the master.
231 *
232 * Returns 1 for successful bringup, 0 if not ready, or -ve errno.
233 */
234static int try_to_bring_up_master(struct master *master,
235 struct component *component)
236{
237 int ret;
238
239 dev_dbg(master->dev, "trying to bring up master\n");
240
241 if (find_components(master)) {
242 dev_dbg(master->dev, "master has incomplete components\n");
243 return 0;
244 }
245
246 if (component && component->master != master) {
247 dev_dbg(master->dev, "master is not for this component (%s)\n",
248 dev_name(component->dev));
249 return 0;
250 }
251
252 if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
253 return -ENOMEM;
254
255 /* Found all components */
256 ret = master->ops->bind(master->dev);
257 if (ret < 0) {
258 devres_release_group(master->dev, NULL);
259 if (ret != -EPROBE_DEFER)
260 dev_info(master->dev, "master bind failed: %d\n", ret);
261 return ret;
262 }
263
264 master->bound = true;
265 return 1;
266}
267
268static int try_to_bring_up_masters(struct component *component)
269{
270 struct master *m;
271 int ret = 0;
272
273 list_for_each_entry(m, &masters, node) {
274 if (!m->bound) {
275 ret = try_to_bring_up_master(m, component);
276 if (ret != 0)
277 break;
278 }
279 }
280
281 return ret;
282}
283
284static void take_down_master(struct master *master)
285{
286 if (master->bound) {
287 master->ops->unbind(master->dev);
288 devres_release_group(master->dev, NULL);
289 master->bound = false;
290 }
291}
292
293static void component_match_release(struct device *master,
294 struct component_match *match)
295{
296 unsigned int i;
297
298 for (i = 0; i < match->num; i++) {
299 struct component_match_array *mc = &match->compare[i];
300
301 if (mc->release)
302 mc->release(master, mc->data);
303 }
304
305 kfree(match->compare);
306}
307
308static void devm_component_match_release(struct device *dev, void *res)
309{
310 component_match_release(dev, res);
311}
312
313static int component_match_realloc(struct device *dev,
314 struct component_match *match, size_t num)
315{
316 struct component_match_array *new;
317
318 if (match->alloc == num)
319 return 0;
320
321 new = kmalloc_array(num, sizeof(*new), GFP_KERNEL);
322 if (!new)
323 return -ENOMEM;
324
325 if (match->compare) {
326 memcpy(new, match->compare, sizeof(*new) *
327 min(match->num, num));
328 kfree(match->compare);
329 }
330 match->compare = new;
331 match->alloc = num;
332
333 return 0;
334}
335
336static void __component_match_add(struct device *master,
337 struct component_match **matchptr,
338 void (*release)(struct device *, void *),
339 int (*compare)(struct device *, void *),
340 int (*compare_typed)(struct device *, int, void *),
341 void *compare_data)
342{
343 struct component_match *match = *matchptr;
344
345 if (IS_ERR(match))
346 return;
347
348 if (!match) {
349 match = devres_alloc(devm_component_match_release,
350 sizeof(*match), GFP_KERNEL);
351 if (!match) {
352 *matchptr = ERR_PTR(-ENOMEM);
353 return;
354 }
355
356 devres_add(master, match);
357
358 *matchptr = match;
359 }
360
361 if (match->num == match->alloc) {
362 size_t new_size = match->alloc + 16;
363 int ret;
364
365 ret = component_match_realloc(master, match, new_size);
366 if (ret) {
367 *matchptr = ERR_PTR(ret);
368 return;
369 }
370 }
371
372 match->compare[match->num].compare = compare;
373 match->compare[match->num].compare_typed = compare_typed;
374 match->compare[match->num].release = release;
375 match->compare[match->num].data = compare_data;
376 match->compare[match->num].component = NULL;
377 match->num++;
378}
379
380/**
381 * component_match_add_release - add a component match entry with release callback
382 * @master: device with the aggregate driver
383 * @matchptr: pointer to the list of component matches
384 * @release: release function for @compare_data
385 * @compare: compare function to match against all components
386 * @compare_data: opaque pointer passed to the @compare function
387 *
388 * Adds a new component match to the list stored in @matchptr, which the @master
389 * aggregate driver needs to function. The list of component matches pointed to
390 * by @matchptr must be initialized to NULL before adding the first match. This
391 * only matches against components added with component_add().
392 *
393 * The allocated match list in @matchptr is automatically released using devm
394 * actions, where upon @release will be called to free any references held by
395 * @compare_data, e.g. when @compare_data is a &device_node that must be
396 * released with of_node_put().
397 *
398 * See also component_match_add() and component_match_add_typed().
399 */
400void component_match_add_release(struct device *master,
401 struct component_match **matchptr,
402 void (*release)(struct device *, void *),
403 int (*compare)(struct device *, void *), void *compare_data)
404{
405 __component_match_add(master, matchptr, release, compare, NULL,
406 compare_data);
407}
408EXPORT_SYMBOL(component_match_add_release);
409
410/**
411 * component_match_add_typed - add a component match entry for a typed component
412 * @master: device with the aggregate driver
413 * @matchptr: pointer to the list of component matches
414 * @compare_typed: compare function to match against all typed components
415 * @compare_data: opaque pointer passed to the @compare function
416 *
417 * Adds a new component match to the list stored in @matchptr, which the @master
418 * aggregate driver needs to function. The list of component matches pointed to
419 * by @matchptr must be initialized to NULL before adding the first match. This
420 * only matches against components added with component_add_typed().
421 *
422 * The allocated match list in @matchptr is automatically released using devm
423 * actions.
424 *
425 * See also component_match_add_release() and component_match_add_typed().
426 */
427void component_match_add_typed(struct device *master,
428 struct component_match **matchptr,
429 int (*compare_typed)(struct device *, int, void *), void *compare_data)
430{
431 __component_match_add(master, matchptr, NULL, NULL, compare_typed,
432 compare_data);
433}
434EXPORT_SYMBOL(component_match_add_typed);
435
436static void free_master(struct master *master)
437{
438 struct component_match *match = master->match;
439 int i;
440
441 component_master_debugfs_del(master);
442 list_del(&master->node);
443
444 if (match) {
445 for (i = 0; i < match->num; i++) {
446 struct component *c = match->compare[i].component;
447 if (c)
448 c->master = NULL;
449 }
450 }
451
452 kfree(master);
453}
454
455/**
456 * component_master_add_with_match - register an aggregate driver
457 * @dev: device with the aggregate driver
458 * @ops: callbacks for the aggregate driver
459 * @match: component match list for the aggregate driver
460 *
461 * Registers a new aggregate driver consisting of the components added to @match
462 * by calling one of the component_match_add() functions. Once all components in
463 * @match are available, it will be assembled by calling
464 * &component_master_ops.bind from @ops. Must be unregistered by calling
465 * component_master_del().
466 */
467int component_master_add_with_match(struct device *dev,
468 const struct component_master_ops *ops,
469 struct component_match *match)
470{
471 struct master *master;
472 int ret;
473
474 /* Reallocate the match array for its true size */
475 ret = component_match_realloc(dev, match, match->num);
476 if (ret)
477 return ret;
478
479 master = kzalloc(sizeof(*master), GFP_KERNEL);
480 if (!master)
481 return -ENOMEM;
482
483 master->dev = dev;
484 master->ops = ops;
485 master->match = match;
486
487 component_master_debugfs_add(master);
488 /* Add to the list of available masters. */
489 mutex_lock(&component_mutex);
490 list_add(&master->node, &masters);
491
492 ret = try_to_bring_up_master(master, NULL);
493
494 if (ret < 0)
495 free_master(master);
496
497 mutex_unlock(&component_mutex);
498
499 return ret < 0 ? ret : 0;
500}
501EXPORT_SYMBOL_GPL(component_master_add_with_match);
502
503/**
504 * component_master_del - unregister an aggregate driver
505 * @dev: device with the aggregate driver
506 * @ops: callbacks for the aggregate driver
507 *
508 * Unregisters an aggregate driver registered with
509 * component_master_add_with_match(). If necessary the aggregate driver is first
510 * disassembled by calling &component_master_ops.unbind from @ops.
511 */
512void component_master_del(struct device *dev,
513 const struct component_master_ops *ops)
514{
515 struct master *master;
516
517 mutex_lock(&component_mutex);
518 master = __master_find(dev, ops);
519 if (master) {
520 take_down_master(master);
521 free_master(master);
522 }
523 mutex_unlock(&component_mutex);
524}
525EXPORT_SYMBOL_GPL(component_master_del);
526
527static void component_unbind(struct component *component,
528 struct master *master, void *data)
529{
530 WARN_ON(!component->bound);
531
532 if (component->ops && component->ops->unbind)
533 component->ops->unbind(component->dev, master->dev, data);
534 component->bound = false;
535
536 /* Release all resources claimed in the binding of this component */
537 devres_release_group(component->dev, component);
538}
539
540/**
541 * component_unbind_all - unbind all components of an aggregate driver
542 * @master_dev: device with the aggregate driver
543 * @data: opaque pointer, passed to all components
544 *
545 * Unbinds all components of the aggregate @dev by passing @data to their
546 * &component_ops.unbind functions. Should be called from
547 * &component_master_ops.unbind.
548 */
549void component_unbind_all(struct device *master_dev, void *data)
550{
551 struct master *master;
552 struct component *c;
553 size_t i;
554
555 WARN_ON(!mutex_is_locked(&component_mutex));
556
557 master = __master_find(master_dev, NULL);
558 if (!master)
559 return;
560
561 /* Unbind components in reverse order */
562 for (i = master->match->num; i--; )
563 if (!master->match->compare[i].duplicate) {
564 c = master->match->compare[i].component;
565 component_unbind(c, master, data);
566 }
567}
568EXPORT_SYMBOL_GPL(component_unbind_all);
569
570static int component_bind(struct component *component, struct master *master,
571 void *data)
572{
573 int ret;
574
575 /*
576 * Each component initialises inside its own devres group.
577 * This allows us to roll-back a failed component without
578 * affecting anything else.
579 */
580 if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
581 return -ENOMEM;
582
583 /*
584 * Also open a group for the device itself: this allows us
585 * to release the resources claimed against the sub-device
586 * at the appropriate moment.
587 */
588 if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
589 devres_release_group(master->dev, NULL);
590 return -ENOMEM;
591 }
592
593 dev_dbg(master->dev, "binding %s (ops %ps)\n",
594 dev_name(component->dev), component->ops);
595
596 ret = component->ops->bind(component->dev, master->dev, data);
597 if (!ret) {
598 component->bound = true;
599
600 /*
601 * Close the component device's group so that resources
602 * allocated in the binding are encapsulated for removal
603 * at unbind. Remove the group on the DRM device as we
604 * can clean those resources up independently.
605 */
606 devres_close_group(component->dev, NULL);
607 devres_remove_group(master->dev, NULL);
608
609 dev_info(master->dev, "bound %s (ops %ps)\n",
610 dev_name(component->dev), component->ops);
611 } else {
612 devres_release_group(component->dev, NULL);
613 devres_release_group(master->dev, NULL);
614
615 if (ret != -EPROBE_DEFER)
616 dev_err(master->dev, "failed to bind %s (ops %ps): %d\n",
617 dev_name(component->dev), component->ops, ret);
618 }
619
620 return ret;
621}
622
623/**
624 * component_bind_all - bind all components of an aggregate driver
625 * @master_dev: device with the aggregate driver
626 * @data: opaque pointer, passed to all components
627 *
628 * Binds all components of the aggregate @dev by passing @data to their
629 * &component_ops.bind functions. Should be called from
630 * &component_master_ops.bind.
631 */
632int component_bind_all(struct device *master_dev, void *data)
633{
634 struct master *master;
635 struct component *c;
636 size_t i;
637 int ret = 0;
638
639 WARN_ON(!mutex_is_locked(&component_mutex));
640
641 master = __master_find(master_dev, NULL);
642 if (!master)
643 return -EINVAL;
644
645 /* Bind components in match order */
646 for (i = 0; i < master->match->num; i++)
647 if (!master->match->compare[i].duplicate) {
648 c = master->match->compare[i].component;
649 ret = component_bind(c, master, data);
650 if (ret)
651 break;
652 }
653
654 if (ret != 0) {
655 for (; i > 0; i--)
656 if (!master->match->compare[i - 1].duplicate) {
657 c = master->match->compare[i - 1].component;
658 component_unbind(c, master, data);
659 }
660 }
661
662 return ret;
663}
664EXPORT_SYMBOL_GPL(component_bind_all);
665
666static int __component_add(struct device *dev, const struct component_ops *ops,
667 int subcomponent)
668{
669 struct component *component;
670 int ret;
671
672 component = kzalloc(sizeof(*component), GFP_KERNEL);
673 if (!component)
674 return -ENOMEM;
675
676 component->ops = ops;
677 component->dev = dev;
678 component->subcomponent = subcomponent;
679
680 dev_dbg(dev, "adding component (ops %ps)\n", ops);
681
682 mutex_lock(&component_mutex);
683 list_add_tail(&component->node, &component_list);
684
685 ret = try_to_bring_up_masters(component);
686 if (ret < 0) {
687 if (component->master)
688 remove_component(component->master, component);
689 list_del(&component->node);
690
691 kfree(component);
692 }
693 mutex_unlock(&component_mutex);
694
695 return ret < 0 ? ret : 0;
696}
697
698/**
699 * component_add_typed - register a component
700 * @dev: component device
701 * @ops: component callbacks
702 * @subcomponent: nonzero identifier for subcomponents
703 *
704 * Register a new component for @dev. Functions in @ops will be call when the
705 * aggregate driver is ready to bind the overall driver by calling
706 * component_bind_all(). See also &struct component_ops.
707 *
708 * @subcomponent must be nonzero and is used to differentiate between multiple
709 * components registerd on the same device @dev. These components are match
710 * using component_match_add_typed().
711 *
712 * The component needs to be unregistered at driver unload/disconnect by
713 * calling component_del().
714 *
715 * See also component_add().
716 */
717int component_add_typed(struct device *dev, const struct component_ops *ops,
718 int subcomponent)
719{
720 if (WARN_ON(subcomponent == 0))
721 return -EINVAL;
722
723 return __component_add(dev, ops, subcomponent);
724}
725EXPORT_SYMBOL_GPL(component_add_typed);
726
727/**
728 * component_add - register a component
729 * @dev: component device
730 * @ops: component callbacks
731 *
732 * Register a new component for @dev. Functions in @ops will be called when the
733 * aggregate driver is ready to bind the overall driver by calling
734 * component_bind_all(). See also &struct component_ops.
735 *
736 * The component needs to be unregistered at driver unload/disconnect by
737 * calling component_del().
738 *
739 * See also component_add_typed() for a variant that allows multipled different
740 * components on the same device.
741 */
742int component_add(struct device *dev, const struct component_ops *ops)
743{
744 return __component_add(dev, ops, 0);
745}
746EXPORT_SYMBOL_GPL(component_add);
747
748/**
749 * component_del - unregister a component
750 * @dev: component device
751 * @ops: component callbacks
752 *
753 * Unregister a component added with component_add(). If the component is bound
754 * into an aggregate driver, this will force the entire aggregate driver, including
755 * all its components, to be unbound.
756 */
757void component_del(struct device *dev, const struct component_ops *ops)
758{
759 struct component *c, *component = NULL;
760
761 mutex_lock(&component_mutex);
762 list_for_each_entry(c, &component_list, node)
763 if (c->dev == dev && c->ops == ops) {
764 list_del(&c->node);
765 component = c;
766 break;
767 }
768
769 if (component && component->master) {
770 take_down_master(component->master);
771 remove_component(component->master, component);
772 }
773
774 mutex_unlock(&component_mutex);
775
776 WARN_ON(!component);
777 kfree(component);
778}
779EXPORT_SYMBOL_GPL(component_del);