aboutsummaryrefslogtreecommitdiff
path: root/drivers/base/component.c
blob: 532a3a5d8f633368380c5e45fd3f4fb204f2e8e0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
// SPDX-License-Identifier: GPL-2.0
/*
 * Componentized device handling.
 *
 * This is work in progress.  We gather up the component devices into a list,
 * and bind them when instructed.  At the moment, we're specific to the DRM
 * subsystem, and only handles one master device, but this doesn't have to be
 * the case.
 */
#include <linux/component.h>
#include <linux/device.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/debugfs.h>

/**
 * DOC: overview
 *
 * The component helper allows drivers to collect a pile of sub-devices,
 * including their bound drivers, into an aggregate driver. Various subsystems
 * already provide functions to get hold of such components, e.g.
 * of_clk_get_by_name(). The component helper can be used when such a
 * subsystem-specific way to find a device is not available: The component
 * helper fills the niche of aggregate drivers for specific hardware, where
 * further standardization into a subsystem would not be practical. The common
 * example is when a logical device (e.g. a DRM display driver) is spread around
 * the SoC on various components (scanout engines, blending blocks, transcoders
 * for various outputs and so on).
 *
 * The component helper also doesn't solve runtime dependencies, e.g. for system
 * suspend and resume operations. See also :ref:`device links<device_link>`.
 *
 * Components are registered using component_add() and unregistered with
 * component_del(), usually from the driver's probe and disconnect functions.
 *
 * Aggregate drivers first assemble a component match list of what they need
 * using component_match_add(). This is then registered as an aggregate driver
 * using component_master_add_with_match(), and unregistered using
 * component_master_del().
 */

struct component;

struct component_match_array {
	void *data;
	int (*compare)(struct device *, void *);
	int (*compare_typed)(struct device *, int, void *);
	void (*release)(struct device *, void *);
	struct component *component;
	bool duplicate;
};

struct component_match {
	size_t alloc;
	size_t num;
	struct component_match_array *compare;
};

struct master {
	struct list_head node;
	bool bound;

	const struct component_master_ops *ops;
	struct device *dev;
	struct component_match *match;
	struct dentry *dentry;
};

struct component {
	struct list_head node;
	struct master *master;
	bool bound;

	const struct component_ops *ops;
	int subcomponent;
	struct device *dev;
};

static DEFINE_MUTEX(component_mutex);
static LIST_HEAD(component_list);
static LIST_HEAD(masters);

#ifdef CONFIG_DEBUG_FS

static struct dentry *component_debugfs_dir;

static int component_devices_show(struct seq_file *s, void *data)
{
	struct master *m = s->private;
	struct component_match *match = m->match;
	size_t i;

	mutex_lock(&component_mutex);
	seq_printf(s, "%-40s %20s\n", "master name", "status");
	seq_puts(s, "-------------------------------------------------------------\n");
	seq_printf(s, "%-40s %20s\n\n",
		   dev_name(m->dev), m->bound ? "bound" : "not bound");

	seq_printf(s, "%-40s %20s\n", "device name", "status");
	seq_puts(s, "-------------------------------------------------------------\n");
	for (i = 0; i < match->num; i++) {
		struct device *d = (struct device *)match->compare[i].data;

		seq_printf(s, "%-40s %20s\n", dev_name(d),
			   match->compare[i].component ?
			   "registered" : "not registered");
	}
	mutex_unlock(&component_mutex);

	return 0;
}

DEFINE_SHOW_ATTRIBUTE(component_devices);

static int __init component_debug_init(void)
{
	component_debugfs_dir = debugfs_create_dir("device_component", NULL);

	return 0;
}

core_initcall(component_debug_init);

static void component_master_debugfs_add(struct master *m)
{
	m->dentry = debugfs_create_file(dev_name(m->dev), 0444,
					component_debugfs_dir,
					m, &component_devices_fops);
}

static void component_master_debugfs_del(struct master *m)
{
	debugfs_remove(m->dentry);
	m->dentry = NULL;
}

#else

static void component_master_debugfs_add(struct master *m)
{ }

static void component_master_debugfs_del(struct master *m)
{ }

#endif

static struct master *__master_find(struct device *dev,
	const struct component_master_ops *ops)
{
	struct master *m;

	list_for_each_entry(m, &masters, node)
		if (m->dev == dev && (!ops || m->ops == ops))
			return m;

	return NULL;
}

static struct component *find_component(struct master *master,
	struct component_match_array *mc)
{
	struct component *c;

	list_for_each_entry(c, &component_list, node) {
		if (c->master && c->master != master)
			continue;

		if (mc->compare && mc->compare(c->dev, mc->data))
			return c;

		if (mc->compare_typed &&
		    mc->compare_typed(c->dev, c->subcomponent, mc->data))
			return c;
	}

	return NULL;
}

static int find_components(struct master *master)
{
	struct component_match *match = master->match;
	size_t i;
	int ret = 0;

	/*
	 * Scan the array of match functions and attach
	 * any components which are found to this master.
	 */
	for (i = 0; i < match->num; i++) {
		struct component_match_array *mc = &match->compare[i];
		struct component *c;

		dev_dbg(master->dev, "Looking for component %zu\n", i);

		if (match->compare[i].component)
			continue;

		c = find_component(master, mc);
		if (!c) {
			ret = -ENXIO;
			break;
		}

		dev_dbg(master->dev, "found component %s, duplicate %u\n", dev_name(c->dev), !!c->master);

		/* Attach this component to the master */
		match->compare[i].duplicate = !!c->master;
		match->compare[i].component = c;
		c->master = master;
	}
	return ret;
}

/* Detach component from associated master */
static void remove_component(struct master *master, struct component *c)
{
	size_t i;

	/* Detach the component from this master. */
	for (i = 0; i < master->match->num; i++)
		if (master->match->compare[i].component == c)
			master->match->compare[i].component = NULL;
}

/*
 * Try to bring up a master.  If component is NULL, we're interested in
 * this master, otherwise it's a component which must be present to try
 * and bring up the master.
 *
 * Returns 1 for successful bringup, 0 if not ready, or -ve errno.
 */
static int try_to_bring_up_master(struct master *master,
	struct component *component)
{
	int ret;

	dev_dbg(master->dev, "trying to bring up master\n");

	if (find_components(master)) {
		dev_dbg(master->dev, "master has incomplete components\n");
		return 0;
	}

	if (component && component->master != master) {
		dev_dbg(master->dev, "master is not for this component (%s)\n",
			dev_name(component->dev));
		return 0;
	}

	if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
		return -ENOMEM;

	/* Found all components */
	ret = master->ops->bind(master->dev);
	if (ret < 0) {
		devres_release_group(master->dev, NULL);
		dev_info(master->dev, "master bind failed: %d\n", ret);
		return ret;
	}

	master->bound = true;
	return 1;
}

static int try_to_bring_up_masters(struct component *component)
{
	struct master *m;
	int ret = 0;

	list_for_each_entry(m, &masters, node) {
		if (!m->bound) {
			ret = try_to_bring_up_master(m, component);
			if (ret != 0)
				break;
		}
	}

	return ret;
}

static void take_down_master(struct master *master)
{
	if (master->bound) {
		master->ops->unbind(master->dev);
		devres_release_group(master->dev, NULL);
		master->bound = false;
	}
}

static void component_match_release(struct device *master,
	struct component_match *match)
{
	unsigned int i;

	for (i = 0; i < match->num; i++) {
		struct component_match_array *mc = &match->compare[i];

		if (mc->release)
			mc->release(master, mc->data);
	}

	kfree(match->compare);
}

static void devm_component_match_release(struct device *dev, void *res)
{
	component_match_release(dev, res);
}

static int component_match_realloc(struct device *dev,
	struct component_match *match, size_t num)
{
	struct component_match_array *new;

	if (match->alloc == num)
		return 0;

	new = kmalloc_array(num, sizeof(*new), GFP_KERNEL);
	if (!new)
		return -ENOMEM;

	if (match->compare) {
		memcpy(new, match->compare, sizeof(*new) *
					    min(match->num, num));
		kfree(match->compare);
	}
	match->compare = new;
	match->alloc = num;

	return 0;
}

static void __component_match_add(struct device *master,
	struct component_match **matchptr,
	void (*release)(struct device *, void *),
	int (*compare)(struct device *, void *),
	int (*compare_typed)(struct device *, int, void *),
	void *compare_data)
{
	struct component_match *match = *matchptr;

	if (IS_ERR(match))
		return;

	if (!match) {
		match = devres_alloc(devm_component_match_release,
				     sizeof(*match), GFP_KERNEL);
		if (!match) {
			*matchptr = ERR_PTR(-ENOMEM);
			return;
		}

		devres_add(master, match);

		*matchptr = match;
	}

	if (match->num == match->alloc) {
		size_t new_size = match->alloc + 16;
		int ret;

		ret = component_match_realloc(master, match, new_size);
		if (ret) {
			*matchptr = ERR_PTR(ret);
			return;
		}
	}

	match->compare[match->num].compare = compare;
	match->compare[match->num].compare_typed = compare_typed;
	match->compare[match->num].release = release;
	match->compare[match->num].data = compare_data;
	match->compare[match->num].component = NULL;
	match->num++;
}

/**
 * component_match_add_release - add a component match entry with release callback
 * @master: device with the aggregate driver
 * @matchptr: pointer to the list of component matches
 * @release: release function for @compare_data
 * @compare: compare function to match against all components
 * @compare_data: opaque pointer passed to the @compare function
 *
 * Adds a new component match to the list stored in @matchptr, which the @master
 * aggregate driver needs to function. The list of component matches pointed to
 * by @matchptr must be initialized to NULL before adding the first match. This
 * only matches against components added with component_add().
 *
 * The allocated match list in @matchptr is automatically released using devm
 * actions, where upon @release will be called to free any references held by
 * @compare_data, e.g. when @compare_data is a &device_node that must be
 * released with of_node_put().
 *
 * See also component_match_add() and component_match_add_typed().
 */
void component_match_add_release(struct device *master,
	struct component_match **matchptr,
	void (*release)(struct device *, void *),
	int (*compare)(struct device *, void *), void *compare_data)
{
	__component_match_add(master, matchptr, release, compare, NULL,
			      compare_data);
}
EXPORT_SYMBOL(component_match_add_release);

/**
 * component_match_add_typed - add a component match entry for a typed component
 * @master: device with the aggregate driver
 * @matchptr: pointer to the list of component matches
 * @compare_typed: compare function to match against all typed components
 * @compare_data: opaque pointer passed to the @compare function
 *
 * Adds a new component match to the list stored in @matchptr, which the @master
 * aggregate driver needs to function. The list of component matches pointed to
 * by @matchptr must be initialized to NULL before adding the first match. This
 * only matches against components added with component_add_typed().
 *
 * The allocated match list in @matchptr is automatically released using devm
 * actions.
 *
 * See also component_match_add_release() and component_match_add_typed().
 */
void component_match_add_typed(struct device *master,
	struct component_match **matchptr,
	int (*compare_typed)(struct device *, int, void *), void *compare_data)
{
	__component_match_add(master, matchptr, NULL, NULL, compare_typed,
			      compare_data);
}
EXPORT_SYMBOL(component_match_add_typed);

static void free_master(struct master *master)
{
	struct component_match *match = master->match;
	int i;

	component_master_debugfs_del(master);
	list_del(&master->node);

	if (match) {
		for (i = 0; i < match->num; i++) {
			struct component *c = match->compare[i].component;
			if (c)
				c->master = NULL;
		}
	}

	kfree(master);
}

/**
 * component_master_add_with_match - register an aggregate driver
 * @dev: device with the aggregate driver
 * @ops: callbacks for the aggregate driver
 * @match: component match list for the aggregate driver
 *
 * Registers a new aggregate driver consisting of the components added to @match
 * by calling one of the component_match_add() functions. Once all components in
 * @match are available, it will be assembled by calling
 * &component_master_ops.bind from @ops. Must be unregistered by calling
 * component_master_del().
 */
int component_master_add_with_match(struct device *dev,
	const struct component_master_ops *ops,
	struct component_match *match)
{
	struct master *master;
	int ret;

	/* Reallocate the match array for its true size */
	ret = component_match_realloc(dev, match, match->num);
	if (ret)
		return ret;

	master = kzalloc(sizeof(*master), GFP_KERNEL);
	if (!master)
		return -ENOMEM;

	master->dev = dev;
	master->ops = ops;
	master->match = match;

	component_master_debugfs_add(master);
	/* Add to the list of available masters. */
	mutex_lock(&component_mutex);
	list_add(&master->node, &masters);

	ret = try_to_bring_up_master(master, NULL);

	if (ret < 0)
		free_master(master);

	mutex_unlock(&component_mutex);

	return ret < 0 ? ret : 0;
}
EXPORT_SYMBOL_GPL(component_master_add_with_match);

/**
 * component_master_del - unregister an aggregate driver
 * @dev: device with the aggregate driver
 * @ops: callbacks for the aggregate driver
 *
 * Unregisters an aggregate driver registered with
 * component_master_add_with_match(). If necessary the aggregate driver is first
 * disassembled by calling &component_master_ops.unbind from @ops.
 */
void component_master_del(struct device *dev,
	const struct component_master_ops *ops)
{
	struct master *master;

	mutex_lock(&component_mutex);
	master = __master_find(dev, ops);
	if (master) {
		take_down_master(master);
		free_master(master);
	}
	mutex_unlock(&component_mutex);
}
EXPORT_SYMBOL_GPL(component_master_del);

static void component_unbind(struct component *component,
	struct master *master, void *data)
{
	WARN_ON(!component->bound);

	component->ops->unbind(component->dev, master->dev, data);
	component->bound = false;

	/* Release all resources claimed in the binding of this component */
	devres_release_group(component->dev, component);
}

/**
 * component_unbind_all - unbind all components of an aggregate driver
 * @master_dev: device with the aggregate driver
 * @data: opaque pointer, passed to all components
 *
 * Unbinds all components of the aggregate @dev by passing @data to their
 * &component_ops.unbind functions. Should be called from
 * &component_master_ops.unbind.
 */
void component_unbind_all(struct device *master_dev, void *data)
{
	struct master *master;
	struct component *c;
	size_t i;

	WARN_ON(!mutex_is_locked(&component_mutex));

	master = __master_find(master_dev, NULL);
	if (!master)
		return;

	/* Unbind components in reverse order */
	for (i = master->match->num; i--; )
		if (!master->match->compare[i].duplicate) {
			c = master->match->compare[i].component;
			component_unbind(c, master, data);
		}
}
EXPORT_SYMBOL_GPL(component_unbind_all);

static int component_bind(struct component *component, struct master *master,
	void *data)
{
	int ret;

	/*
	 * Each component initialises inside its own devres group.
	 * This allows us to roll-back a failed component without
	 * affecting anything else.
	 */
	if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
		return -ENOMEM;

	/*
	 * Also open a group for the device itself: this allows us
	 * to release the resources claimed against the sub-device
	 * at the appropriate moment.
	 */
	if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
		devres_release_group(master->dev, NULL);
		return -ENOMEM;
	}

	dev_dbg(master->dev, "binding %s (ops %ps)\n",
		dev_name(component->dev), component->ops);

	ret = component->ops->bind(component->dev, master->dev, data);
	if (!ret) {
		component->bound = true;

		/*
		 * Close the component device's group so that resources
		 * allocated in the binding are encapsulated for removal
		 * at unbind.  Remove the group on the DRM device as we
		 * can clean those resources up independently.
		 */
		devres_close_group(component->dev, NULL);
		devres_remove_group(master->dev, NULL);

		dev_info(master->dev, "bound %s (ops %ps)\n",
			 dev_name(component->dev), component->ops);
	} else {
		devres_release_group(component->dev, NULL);
		devres_release_group(master->dev, NULL);

		dev_err(master->dev, "failed to bind %s (ops %ps): %d\n",
			dev_name(component->dev), component->ops, ret);
	}

	return ret;
}

/**
 * component_bind_all - bind all components of an aggregate driver
 * @master_dev: device with the aggregate driver
 * @data: opaque pointer, passed to all components
 *
 * Binds all components of the aggregate @dev by passing @data to their
 * &component_ops.bind functions. Should be called from
 * &component_master_ops.bind.
 */
int component_bind_all(struct device *master_dev, void *data)
{
	struct master *master;
	struct component *c;
	size_t i;
	int ret = 0;

	WARN_ON(!mutex_is_locked(&component_mutex));

	master = __master_find(master_dev, NULL);
	if (!master)
		return -EINVAL;

	/* Bind components in match order */
	for (i = 0; i < master->match->num; i++)
		if (!master->match->compare[i].duplicate) {
			c = master->match->compare[i].component;
			ret = component_bind(c, master, data);
			if (ret)
				break;
		}

	if (ret != 0) {
		for (; i > 0; i--)
			if (!master->match->compare[i - 1].duplicate) {
				c = master->match->compare[i - 1].component;
				component_unbind(c, master, data);
			}
	}

	return ret;
}
EXPORT_SYMBOL_GPL(component_bind_all);

static int __component_add(struct device *dev, const struct component_ops *ops,
	int subcomponent)
{
	struct component *component;
	int ret;

	component = kzalloc(sizeof(*component), GFP_KERNEL);
	if (!component)
		return -ENOMEM;

	component->ops = ops;
	component->dev = dev;
	component->subcomponent = subcomponent;

	dev_dbg(dev, "adding component (ops %ps)\n", ops);

	mutex_lock(&component_mutex);
	list_add_tail(&component->node, &component_list);

	ret = try_to_bring_up_masters(component);
	if (ret < 0) {
		if (component->master)
			remove_component(component->master, component);
		list_del(&component->node);

		kfree(component);
	}
	mutex_unlock(&component_mutex);

	return ret < 0 ? ret : 0;
}

/**
 * component_add_typed - register a component
 * @dev: component device
 * @ops: component callbacks
 * @subcomponent: nonzero identifier for subcomponents
 *
 * Register a new component for @dev. Functions in @ops will be call when the
 * aggregate driver is ready to bind the overall driver by calling
 * component_bind_all(). See also &struct component_ops.
 *
 * @subcomponent must be nonzero and is used to differentiate between multiple
 * components registerd on the same device @dev. These components are match
 * using component_match_add_typed().
 *
 * The component needs to be unregistered at driver unload/disconnect by
 * calling component_del().
 *
 * See also component_add().
 */
int component_add_typed(struct device *dev, const struct component_ops *ops,
	int subcomponent)
{
	if (WARN_ON(subcomponent == 0))
		return -EINVAL;

	return __component_add(dev, ops, subcomponent);
}
EXPORT_SYMBOL_GPL(component_add_typed);

/**
 * component_add - register a component
 * @dev: component device
 * @ops: component callbacks
 *
 * Register a new component for @dev. Functions in @ops will be called when the
 * aggregate driver is ready to bind the overall driver by calling
 * component_bind_all(). See also &struct component_ops.
 *
 * The component needs to be unregistered at driver unload/disconnect by
 * calling component_del().
 *
 * See also component_add_typed() for a variant that allows multipled different
 * components on the same device.
 */
int component_add(struct device *dev, const struct component_ops *ops)
{
	return __component_add(dev, ops, 0);
}
EXPORT_SYMBOL_GPL(component_add);

/**
 * component_del - unregister a component
 * @dev: component device
 * @ops: component callbacks
 *
 * Unregister a component added with component_add(). If the component is bound
 * into an aggregate driver, this will force the entire aggregate driver, including
 * all its components, to be unbound.
 */
void component_del(struct device *dev, const struct component_ops *ops)
{
	struct component *c, *component = NULL;

	mutex_lock(&component_mutex);
	list_for_each_entry(c, &component_list, node)
		if (c->dev == dev && c->ops == ops) {
			list_del(&c->node);
			component = c;
			break;
		}

	if (component && component->master) {
		take_down_master(component->master);
		remove_component(component->master, component);
	}

	mutex_unlock(&component_mutex);

	WARN_ON(!component);
	kfree(component);
}
EXPORT_SYMBOL_GPL(component_del);

MODULE_LICENSE("GPL v2");