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
19/**
20 * DOC: overview
21 *
22 * The component helper allows drivers to collect a pile of sub-devices,
23 * including their bound drivers, into an aggregate driver. Various subsystems
24 * already provide functions to get hold of such components, e.g.
25 * of_clk_get_by_name(). The component helper can be used when such a
26 * subsystem-specific way to find a device is not available: The component
27 * helper fills the niche of aggregate drivers for specific hardware, where
28 * further standardization into a subsystem would not be practical. The common
29 * example is when a logical device (e.g. a DRM display driver) is spread around
30 * the SoC on various components (scanout engines, blending blocks, transcoders
31 * for various outputs and so on).
32 *
33 * The component helper also doesn't solve runtime dependencies, e.g. for system
34 * suspend and resume operations. See also :ref:`device links<device_link>`.
35 *
36 * Components are registered using component_add() and unregistered with
37 * component_del(), usually from the driver's probe and disconnect functions.
38 *
39 * Aggregate drivers first assemble a component match list of what they need
40 * using component_match_add(). This is then registered as an aggregate driver
41 * using component_master_add_with_match(), and unregistered using
42 * component_master_del().
43 */
44
45struct component;
46
47struct component_match_array {
48 void *data;
49 int (*compare)(struct device *, void *);
50 int (*compare_typed)(struct device *, int, void *);
51 void (*release)(struct device *, void *);
52 struct component *component;
53 bool duplicate;
54};
55
56struct component_match {
57 size_t alloc;
58 size_t num;
59 struct component_match_array *compare;
60};
61
62struct master {
63 struct list_head node;
64 bool bound;
65
66 const struct component_master_ops *ops;
67 struct device *dev;
68 struct component_match *match;
69 struct dentry *dentry;
70};
71
72struct component {
73 struct list_head node;
74 struct master *master;
75 bool bound;
76
77 const struct component_ops *ops;
78 int subcomponent;
79 struct device *dev;
80};
81
82static DEFINE_MUTEX(component_mutex);
83static LIST_HEAD(component_list);
84static LIST_HEAD(masters);
85
86#ifdef CONFIG_DEBUG_FS
87
88static struct dentry *component_debugfs_dir;
89
90static int component_devices_show(struct seq_file *s, void *data)
91{
92 struct master *m = s->private;
93 struct component_match *match = m->match;
94 size_t i;
95
96 mutex_lock(&component_mutex);
97 seq_printf(s, "%-40s %20s\n", "master name", "status");
98 seq_puts(s, "-------------------------------------------------------------\n");
99 seq_printf(s, "%-40s %20s\n\n",
100 dev_name(m->dev), m->bound ? "bound" : "not bound");
101
102 seq_printf(s, "%-40s %20s\n", "device name", "status");
103 seq_puts(s, "-------------------------------------------------------------\n");
104 for (i = 0; i < match->num; i++) {
105 struct device *d = (struct device *)match->compare[i].data;
106
107 seq_printf(s, "%-40s %20s\n", dev_name(d),
108 match->compare[i].component ?
109 "registered" : "not registered");
110 }
111 mutex_unlock(&component_mutex);
112
113 return 0;
114}
115
116DEFINE_SHOW_ATTRIBUTE(component_devices);
117
118static int __init component_debug_init(void)
119{
120 component_debugfs_dir = debugfs_create_dir("device_component", NULL);
121
122 return 0;
123}
124
125core_initcall(component_debug_init);
126
127static void component_master_debugfs_add(struct master *m)
128{
129 m->dentry = debugfs_create_file(dev_name(m->dev), 0444,
130 component_debugfs_dir,
131 m, &component_devices_fops);
132}
133
134static void component_master_debugfs_del(struct master *m)
135{
136 debugfs_remove(m->dentry);
137 m->dentry = NULL;
138}
139
140#else
141
142static void component_master_debugfs_add(struct master *m)
143{ }
144
145static void component_master_debugfs_del(struct master *m)
146{ }
147
148#endif
149
150static struct master *__master_find(struct device *dev,
151 const struct component_master_ops *ops)
152{
153 struct master *m;
154
155 list_for_each_entry(m, &masters, node)
156 if (m->dev == dev && (!ops || m->ops == ops))
157 return m;
158
159 return NULL;
160}
161
162static struct component *find_component(struct master *master,
163 struct component_match_array *mc)
164{
165 struct component *c;
166
167 list_for_each_entry(c, &component_list, node) {
168 if (c->master && c->master != master)
169 continue;
170
171 if (mc->compare && mc->compare(c->dev, mc->data))
172 return c;
173
174 if (mc->compare_typed &&
175 mc->compare_typed(c->dev, c->subcomponent, mc->data))
176 return c;
177 }
178
179 return NULL;
180}
181
182static int find_components(struct master *master)
183{
184 struct component_match *match = master->match;
185 size_t i;
186 int ret = 0;
187
188 /*
189 * Scan the array of match functions and attach
190 * any components which are found to this master.
191 */
192 for (i = 0; i < match->num; i++) {
193 struct component_match_array *mc = &match->compare[i];
194 struct component *c;
195
196 dev_dbg(master->dev, "Looking for component %zu\n", i);
197
198 if (match->compare[i].component)
199 continue;
200
201 c = find_component(master, mc);
202 if (!c) {
203 ret = -ENXIO;
204 break;
205 }
206
207 dev_dbg(master->dev, "found component %s, duplicate %u\n", dev_name(c->dev), !!c->master);
208
209 /* Attach this component to the master */
210 match->compare[i].duplicate = !!c->master;
211 match->compare[i].component = c;
212 c->master = master;
213 }
214 return ret;
215}
216
217/* Detach component from associated master */
218static void remove_component(struct master *master, struct component *c)
219{
220 size_t i;
221
222 /* Detach the component from this master. */
223 for (i = 0; i < master->match->num; i++)
224 if (master->match->compare[i].component == c)
225 master->match->compare[i].component = NULL;
226}
227
228/*
229 * Try to bring up a master. If component is NULL, we're interested in
230 * this master, otherwise it's a component which must be present to try
231 * and bring up the master.
232 *
233 * Returns 1 for successful bringup, 0 if not ready, or -ve errno.
234 */
235static int try_to_bring_up_master(struct master *master,
236 struct component *component)
237{
238 int ret;
239
240 dev_dbg(master->dev, "trying to bring up master\n");
241
242 if (find_components(master)) {
243 dev_dbg(master->dev, "master has incomplete components\n");
244 return 0;
245 }
246
247 if (component && component->master != master) {
248 dev_dbg(master->dev, "master is not for this component (%s)\n",
249 dev_name(component->dev));
250 return 0;
251 }
252
253 if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
254 return -ENOMEM;
255
256 /* Found all components */
257 ret = master->ops->bind(master->dev);
258 if (ret < 0) {
259 devres_release_group(master->dev, NULL);
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 component->ops->unbind(component->dev, master->dev, data);
533 component->bound = false;
534
535 /* Release all resources claimed in the binding of this component */
536 devres_release_group(component->dev, component);
537}
538
539/**
540 * component_unbind_all - unbind all components of an aggregate driver
541 * @master_dev: device with the aggregate driver
542 * @data: opaque pointer, passed to all components
543 *
544 * Unbinds all components of the aggregate @dev by passing @data to their
545 * &component_ops.unbind functions. Should be called from
546 * &component_master_ops.unbind.
547 */
548void component_unbind_all(struct device *master_dev, void *data)
549{
550 struct master *master;
551 struct component *c;
552 size_t i;
553
554 WARN_ON(!mutex_is_locked(&component_mutex));
555
556 master = __master_find(master_dev, NULL);
557 if (!master)
558 return;
559
560 /* Unbind components in reverse order */
561 for (i = master->match->num; i--; )
562 if (!master->match->compare[i].duplicate) {
563 c = master->match->compare[i].component;
564 component_unbind(c, master, data);
565 }
566}
567EXPORT_SYMBOL_GPL(component_unbind_all);
568
569static int component_bind(struct component *component, struct master *master,
570 void *data)
571{
572 int ret;
573
574 /*
575 * Each component initialises inside its own devres group.
576 * This allows us to roll-back a failed component without
577 * affecting anything else.
578 */
579 if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
580 return -ENOMEM;
581
582 /*
583 * Also open a group for the device itself: this allows us
584 * to release the resources claimed against the sub-device
585 * at the appropriate moment.
586 */
587 if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
588 devres_release_group(master->dev, NULL);
589 return -ENOMEM;
590 }
591
592 dev_dbg(master->dev, "binding %s (ops %ps)\n",
593 dev_name(component->dev), component->ops);
594
595 ret = component->ops->bind(component->dev, master->dev, data);
596 if (!ret) {
597 component->bound = true;
598
599 /*
600 * Close the component device's group so that resources
601 * allocated in the binding are encapsulated for removal
602 * at unbind. Remove the group on the DRM device as we
603 * can clean those resources up independently.
604 */
605 devres_close_group(component->dev, NULL);
606 devres_remove_group(master->dev, NULL);
607
608 dev_info(master->dev, "bound %s (ops %ps)\n",
609 dev_name(component->dev), component->ops);
610 } else {
611 devres_release_group(component->dev, NULL);
612 devres_release_group(master->dev, NULL);
613
614 dev_err(master->dev, "failed to bind %s (ops %ps): %d\n",
615 dev_name(component->dev), component->ops, ret);
616 }
617
618 return ret;
619}
620
621/**
622 * component_bind_all - bind all components of an aggregate driver
623 * @master_dev: device with the aggregate driver
624 * @data: opaque pointer, passed to all components
625 *
626 * Binds all components of the aggregate @dev by passing @data to their
627 * &component_ops.bind functions. Should be called from
628 * &component_master_ops.bind.
629 */
630int component_bind_all(struct device *master_dev, void *data)
631{
632 struct master *master;
633 struct component *c;
634 size_t i;
635 int ret = 0;
636
637 WARN_ON(!mutex_is_locked(&component_mutex));
638
639 master = __master_find(master_dev, NULL);
640 if (!master)
641 return -EINVAL;
642
643 /* Bind components in match order */
644 for (i = 0; i < master->match->num; i++)
645 if (!master->match->compare[i].duplicate) {
646 c = master->match->compare[i].component;
647 ret = component_bind(c, master, data);
648 if (ret)
649 break;
650 }
651
652 if (ret != 0) {
653 for (; i > 0; i--)
654 if (!master->match->compare[i - 1].duplicate) {
655 c = master->match->compare[i - 1].component;
656 component_unbind(c, master, data);
657 }
658 }
659
660 return ret;
661}
662EXPORT_SYMBOL_GPL(component_bind_all);
663
664static int __component_add(struct device *dev, const struct component_ops *ops,
665 int subcomponent)
666{
667 struct component *component;
668 int ret;
669
670 component = kzalloc(sizeof(*component), GFP_KERNEL);
671 if (!component)
672 return -ENOMEM;
673
674 component->ops = ops;
675 component->dev = dev;
676 component->subcomponent = subcomponent;
677
678 dev_dbg(dev, "adding component (ops %ps)\n", ops);
679
680 mutex_lock(&component_mutex);
681 list_add_tail(&component->node, &component_list);
682
683 ret = try_to_bring_up_masters(component);
684 if (ret < 0) {
685 if (component->master)
686 remove_component(component->master, component);
687 list_del(&component->node);
688
689 kfree(component);
690 }
691 mutex_unlock(&component_mutex);
692
693 return ret < 0 ? ret : 0;
694}
695
696/**
697 * component_add_typed - register a component
698 * @dev: component device
699 * @ops: component callbacks
700 * @subcomponent: nonzero identifier for subcomponents
701 *
702 * Register a new component for @dev. Functions in @ops will be call when the
703 * aggregate driver is ready to bind the overall driver by calling
704 * component_bind_all(). See also &struct component_ops.
705 *
706 * @subcomponent must be nonzero and is used to differentiate between multiple
707 * components registerd on the same device @dev. These components are match
708 * using component_match_add_typed().
709 *
710 * The component needs to be unregistered at driver unload/disconnect by
711 * calling component_del().
712 *
713 * See also component_add().
714 */
715int component_add_typed(struct device *dev, const struct component_ops *ops,
716 int subcomponent)
717{
718 if (WARN_ON(subcomponent == 0))
719 return -EINVAL;
720
721 return __component_add(dev, ops, subcomponent);
722}
723EXPORT_SYMBOL_GPL(component_add_typed);
724
725/**
726 * component_add - register a component
727 * @dev: component device
728 * @ops: component callbacks
729 *
730 * Register a new component for @dev. Functions in @ops will be called when the
731 * aggregate driver is ready to bind the overall driver by calling
732 * component_bind_all(). See also &struct component_ops.
733 *
734 * The component needs to be unregistered at driver unload/disconnect by
735 * calling component_del().
736 *
737 * See also component_add_typed() for a variant that allows multipled different
738 * components on the same device.
739 */
740int component_add(struct device *dev, const struct component_ops *ops)
741{
742 return __component_add(dev, ops, 0);
743}
744EXPORT_SYMBOL_GPL(component_add);
745
746/**
747 * component_del - unregister a component
748 * @dev: component device
749 * @ops: component callbacks
750 *
751 * Unregister a component added with component_add(). If the component is bound
752 * into an aggregate driver, this will force the entire aggregate driver, including
753 * all its components, to be unbound.
754 */
755void component_del(struct device *dev, const struct component_ops *ops)
756{
757 struct component *c, *component = NULL;
758
759 mutex_lock(&component_mutex);
760 list_for_each_entry(c, &component_list, node)
761 if (c->dev == dev && c->ops == ops) {
762 list_del(&c->node);
763 component = c;
764 break;
765 }
766
767 if (component && component->master) {
768 take_down_master(component->master);
769 remove_component(component->master, component);
770 }
771
772 mutex_unlock(&component_mutex);
773
774 WARN_ON(!component);
775 kfree(component);
776}
777EXPORT_SYMBOL_GPL(component_del);
778
779MODULE_LICENSE("GPL v2");
780