summaryrefslogtreecommitdiffstats
path: root/include/media/media-entity.h
blob: fe485d367985650a1c4a88ff86e1c10b71d82ea3 (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
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
/*
 * Media entity
 *
 * Copyright (C) 2010 Nokia Corporation
 *
 * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
 *	     Sakari Ailus <sakari.ailus@iki.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifndef _MEDIA_ENTITY_H
#define _MEDIA_ENTITY_H

#include <linux/bitmap.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/media.h>

/* Enums used internally at the media controller to represent graphs */

/**
 * enum media_gobj_type - type of a graph object
 *
 * @MEDIA_GRAPH_ENTITY:		Identify a media entity
 * @MEDIA_GRAPH_PAD:		Identify a media pad
 * @MEDIA_GRAPH_LINK:		Identify a media link
 * @MEDIA_GRAPH_INTF_DEVNODE:	Identify a media Kernel API interface via
 *				a device node
 */
enum media_gobj_type {
	MEDIA_GRAPH_ENTITY,
	MEDIA_GRAPH_PAD,
	MEDIA_GRAPH_LINK,
	MEDIA_GRAPH_INTF_DEVNODE,
};

#define MEDIA_BITS_PER_TYPE		8
#define MEDIA_BITS_PER_ID		(32 - MEDIA_BITS_PER_TYPE)
#define MEDIA_ID_MASK			 GENMASK_ULL(MEDIA_BITS_PER_ID - 1, 0)

/* Structs to represent the objects that belong to a media graph */

/**
 * struct media_gobj - Define a graph object.
 *
 * @mdev:	Pointer to the struct media_device that owns the object
 * @id:		Non-zero object ID identifier. The ID should be unique
 *		inside a media_device, as it is composed by
 *		%MEDIA_BITS_PER_TYPE to store the type plus
 *		%MEDIA_BITS_PER_ID to store the ID
 * @list:	List entry stored in one of the per-type mdev object lists
 *
 * All objects on the media graph should have this struct embedded
 */
struct media_gobj {
	struct media_device	*mdev;
	u32			id;
	struct list_head	list;
};

#define MEDIA_ENTITY_ENUM_MAX_DEPTH	16

/**
 * struct media_entity_enum - An enumeration of media entities.
 *
 * @bmap:	Bit map in which each bit represents one entity at struct
 *		media_entity->internal_idx.
 * @idx_max:	Number of bits in bmap
 */
struct media_entity_enum {
	unsigned long *bmap;
	int idx_max;
};

/**
 * struct media_entity_graph - Media graph traversal state
 *
 * @stack:		Graph traversal stack; the stack contains information
 *			on the path the media entities to be walked and the
 *			links through which they were reached.
 * @ent_enum:		Visited entities
 * @top:		The top of the stack
 */
struct media_entity_graph {
	struct {
		struct media_entity *entity;
		struct list_head *link;
	} stack[MEDIA_ENTITY_ENUM_MAX_DEPTH];

	struct media_entity_enum ent_enum;
	int top;
};

/*
 * struct media_pipeline - Media pipeline related information
 *
 * @streaming_count:	Streaming start count - streaming stop count
 * @graph:		Media graph walk during pipeline start / stop
 */
struct media_pipeline {
	int streaming_count;
	struct media_entity_graph graph;
};

/**
 * struct media_link - A link object part of a media graph.
 *
 * @graph_obj:	Embedded structure containing the media object common data
 * @list:	Linked list associated with an entity or an interface that
 *		owns the link.
 * @gobj0:	Part of a union. Used to get the pointer for the first
 *		graph_object of the link.
 * @source:	Part of a union. Used only if the first object (gobj0) is
 *		a pad. In that case, it represents the source pad.
 * @intf:	Part of a union. Used only if the first object (gobj0) is
 *		an interface.
 * @gobj1:	Part of a union. Used to get the pointer for the second
 *		graph_object of the link.
 * @source:	Part of a union. Used only if the second object (gobj1) is
 *		a pad. In that case, it represents the sink pad.
 * @entity:	Part of a union. Used only if the second object (gobj1) is
 *		an entity.
 * @reverse:	Pointer to the link for the reverse direction of a pad to pad
 *		link.
 * @flags:	Link flags, as defined in uapi/media.h (MEDIA_LNK_FL_*)
 * @is_backlink: Indicate if the link is a backlink.
 */
struct media_link {
	struct media_gobj graph_obj;
	struct list_head list;
	union {
		struct media_gobj *gobj0;
		struct media_pad *source;
		struct media_interface *intf;
	};
	union {
		struct media_gobj *gobj1;
		struct media_pad *sink;
		struct media_entity *entity;
	};
	struct media_link *reverse;
	unsigned long flags;
	bool is_backlink;
};

/**
 * struct media_pad - A media pad graph object.
 *
 * @graph_obj:	Embedded structure containing the media object common data
 * @entity:	Entity this pad belongs to
 * @index:	Pad index in the entity pads array, numbered from 0 to n
 * @flags:	Pad flags, as defined in uapi/media.h (MEDIA_PAD_FL_*)
 */
struct media_pad {
	struct media_gobj graph_obj;	/* must be first field in struct */
	struct media_entity *entity;
	u16 index;
	unsigned long flags;
};

/**
 * struct media_entity_operations - Media entity operations
 * @link_setup:		Notify the entity of link changes. The operation can
 *			return an error, in which case link setup will be
 *			cancelled. Optional.
 * @link_validate:	Return whether a link is valid from the entity point of
 *			view. The media_entity_pipeline_start() function
 *			validates all links by calling this operation. Optional.
 */
struct media_entity_operations {
	int (*link_setup)(struct media_entity *entity,
			  const struct media_pad *local,
			  const struct media_pad *remote, u32 flags);
	int (*link_validate)(struct media_link *link);
};

/**
 * struct media_entity - A media entity graph object.
 *
 * @graph_obj:	Embedded structure containing the media object common data.
 * @name:	Entity name.
 * @function:	Entity main function, as defined in uapi/media.h
 *		(MEDIA_ENT_F_*)
 * @flags:	Entity flags, as defined in uapi/media.h (MEDIA_ENT_FL_*)
 * @num_pads:	Number of sink and source pads.
 * @num_links:	Total number of links, forward and back, enabled and disabled.
 * @num_backlinks: Number of backlinks
 * @internal_idx: An unique internal entity specific number. The numbers are
 *		re-used if entities are unregistered or registered again.
 * @pads:	Pads array with the size defined by @num_pads.
 * @links:	List of data links.
 * @ops:	Entity operations.
 * @stream_count: Stream count for the entity.
 * @use_count:	Use count for the entity.
 * @pipe:	Pipeline this entity belongs to.
 * @info:	Union with devnode information.  Kept just for backward
 *		compatibility.
 * @major:	Devnode major number (zero if not applicable). Kept just
 *		for backward compatibility.
 * @minor:	Devnode minor number (zero if not applicable). Kept just
 *		for backward compatibility.
 *
 * NOTE: @stream_count and @use_count reference counts must never be
 * negative, but are signed integers on purpose: a simple WARN_ON(<0) check
 * can be used to detect reference count bugs that would make them negative.
 */
struct media_entity {
	struct media_gobj graph_obj;	/* must be first field in struct */
	const char *name;
	u32 function;
	unsigned long flags;

	u16 num_pads;
	u16 num_links;
	u16 num_backlinks;
	int internal_idx;

	struct media_pad *pads;
	struct list_head links;

	const struct media_entity_operations *ops;

	/* Reference counts must never be negative, but are signed integers on
	 * purpose: a simple WARN_ON(<0) check can be used to detect reference
	 * count bugs that would make them negative.
	 */
	int stream_count;
	int use_count;

	struct media_pipeline *pipe;

	union {
		struct {
			u32 major;
			u32 minor;
		} dev;
	} info;
};

/**
 * struct media_interface - A media interface graph object.
 *
 * @graph_obj:		embedded graph object
 * @links:		List of links pointing to graph entities
 * @type:		Type of the interface as defined in the
 *			uapi/media/media.h header, e. g.
 *			MEDIA_INTF_T_*
 * @flags:		Interface flags as defined in uapi/media/media.h
 */
struct media_interface {
	struct media_gobj		graph_obj;
	struct list_head		links;
	u32				type;
	u32				flags;
};

/**
 * struct media_intf_devnode - A media interface via a device node.
 *
 * @intf:	embedded interface object
 * @major:	Major number of a device node
 * @minor:	Minor number of a device node
 */
struct media_intf_devnode {
	struct media_interface		intf;

	/* Should match the fields at media_v2_intf_devnode */
	u32				major;
	u32				minor;
};

/**
 * media_entity_id() - return the media entity graph object id
 *
 * @entity:	pointer to entity
 */
static inline u32 media_entity_id(struct media_entity *entity)
{
	return entity->graph_obj.id;
}

/**
 * media_type() - return the media object type
 *
 * @gobj:	pointer to the media graph object
 */
static inline enum media_gobj_type media_type(struct media_gobj *gobj)
{
	return gobj->id >> MEDIA_BITS_PER_ID;
}

/**
 * media_id() - return the media object ID
 *
 * @gobj:	pointer to the media graph object
 */
static inline u32 media_id(struct media_gobj *gobj)
{
	return gobj->id & MEDIA_ID_MASK;
}

/**
 * media_gobj_gen_id() - encapsulates type and ID on at the object ID
 *
 * @type:	object type as define at enum &media_gobj_type.
 * @local_id:	next ID, from struct &media_device.@id.
 */
static inline u32 media_gobj_gen_id(enum media_gobj_type type, u64 local_id)
{
	u32 id;

	id = type << MEDIA_BITS_PER_ID;
	id |= local_id & MEDIA_ID_MASK;

	return id;
}

/**
 * is_media_entity_v4l2_io() - identify if the entity main function
 *			       is a V4L2 I/O
 *
 * @entity:	pointer to entity
 *
 * Return: true if the entity main function is one of the V4L2 I/O types
 *	(video, VBI or SDR radio); false otherwise.
 */
static inline bool is_media_entity_v4l2_io(struct media_entity *entity)
{
	if (!entity)
		return false;

	switch (entity->function) {
	case MEDIA_ENT_F_IO_V4L:
	case MEDIA_ENT_F_IO_VBI:
	case MEDIA_ENT_F_IO_SWRADIO:
		return true;
	default:
		return false;
	}
}

/**
 * is_media_entity_v4l2_subdev - return true if the entity main function is
 *				 associated with the V4L2 API subdev usage
 *
 * @entity:	pointer to entity
 *
 * This is an ancillary function used by subdev-based V4L2 drivers.
 * It checks if the entity function is one of functions used by a V4L2 subdev,
 * e. g. camera-relatef functions, analog TV decoder, TV tuner, V4L2 DSPs.
 */
static inline bool is_media_entity_v4l2_subdev(struct media_entity *entity)
{
	if (!entity)
		return false;

	switch (entity->function) {
	case MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN:
	case MEDIA_ENT_F_CAM_SENSOR:
	case MEDIA_ENT_F_FLASH:
	case MEDIA_ENT_F_LENS:
	case MEDIA_ENT_F_ATV_DECODER:
	case MEDIA_ENT_F_TUNER:
		return true;

	default:
		return false;
	}
}

/**
 * __media_entity_enum_init - Initialise an entity enumeration
 *
 * @ent_enum: Entity enumeration to be initialised
 * @idx_max: Maximum number of entities in the enumeration
 *
 * Return: Returns zero on success or a negative error code.
 */
__must_check int __media_entity_enum_init(struct media_entity_enum *ent_enum,
					  int idx_max);

/**
 * media_entity_enum_cleanup - Release resources of an entity enumeration
 *
 * @ent_enum: Entity enumeration to be released
 */
void media_entity_enum_cleanup(struct media_entity_enum *ent_enum);

/**
 * media_entity_enum_zero - Clear the entire enum
 *
 * @ent_enum: Entity enumeration to be cleared
 */
static inline void media_entity_enum_zero(struct media_entity_enum *ent_enum)
{
	bitmap_zero(ent_enum->bmap, ent_enum->idx_max);
}

/**
 * media_entity_enum_set - Mark a single entity in the enum
 *
 * @ent_enum: Entity enumeration
 * @entity: Entity to be marked
 */
static inline void media_entity_enum_set(struct media_entity_enum *ent_enum,
					 struct media_entity *entity)
{
	if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
		return;

	__set_bit(entity->internal_idx, ent_enum->bmap);
}

/**
 * media_entity_enum_clear - Unmark a single entity in the enum
 *
 * @ent_enum: Entity enumeration
 * @entity: Entity to be unmarked
 */
static inline void media_entity_enum_clear(struct media_entity_enum *ent_enum,
					   struct media_entity *entity)
{
	if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
		return;

	__clear_bit(entity->internal_idx, ent_enum->bmap);
}

/**
 * media_entity_enum_test - Test whether the entity is marked
 *
 * @ent_enum: Entity enumeration
 * @entity: Entity to be tested
 *
 * Returns true if the entity was marked.
 */
static inline bool media_entity_enum_test(struct media_entity_enum *ent_enum,
					  struct media_entity *entity)
{
	if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
		return true;

	return test_bit(entity->internal_idx, ent_enum->bmap);
}

/**
 * media_entity_enum_test - Test whether the entity is marked, and mark it
 *
 * @ent_enum: Entity enumeration
 * @entity: Entity to be tested
 *
 * Returns true if the entity was marked, and mark it before doing so.
 */
static inline bool
media_entity_enum_test_and_set(struct media_entity_enum *ent_enum,
			       struct media_entity *entity)
{
	if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
		return true;

	return __test_and_set_bit(entity->internal_idx, ent_enum->bmap);
}

/**
 * media_entity_enum_empty - Test whether the entire enum is empty
 *
 * @ent_enum: Entity enumeration
 *
 * Returns true if the entity was marked.
 */
static inline bool media_entity_enum_empty(struct media_entity_enum *ent_enum)
{
	return bitmap_empty(ent_enum->bmap, ent_enum->idx_max);
}

/**
 * media_entity_enum_intersects - Test whether two enums intersect
 *
 * @ent_enum1: First entity enumeration
 * @ent_enum2: Second entity enumeration
 *
 * Returns true if entity enumerations e and f intersect, otherwise false.
 */
static inline bool media_entity_enum_intersects(
	struct media_entity_enum *ent_enum1,
	struct media_entity_enum *ent_enum2)
{
	WARN_ON(ent_enum1->idx_max != ent_enum2->idx_max);

	return bitmap_intersects(ent_enum1->bmap, ent_enum2->bmap,
				 min(ent_enum1->idx_max, ent_enum2->idx_max));
}

#define gobj_to_entity(gobj) \
		container_of(gobj, struct media_entity, graph_obj)

#define gobj_to_pad(gobj) \
		container_of(gobj, struct media_pad, graph_obj)

#define gobj_to_link(gobj) \
		container_of(gobj, struct media_link, graph_obj)

#define gobj_to_link(gobj) \
		container_of(gobj, struct media_link, graph_obj)

#define gobj_to_pad(gobj) \
		container_of(gobj, struct media_pad, graph_obj)

#define gobj_to_intf(gobj) \
		container_of(gobj, struct media_interface, graph_obj)

#define intf_to_devnode(intf) \
		container_of(intf, struct media_intf_devnode, intf)

/**
 *  media_gobj_create - Initialize a graph object
 *
 * @mdev:	Pointer to the media_device that contains the object
 * @type:	Type of the object
 * @gobj:	Pointer to the graph object
 *
 * This routine initializes the embedded struct media_gobj inside a
 * media graph object. It is called automatically if media_*_create()
 * calls are used. However, if the object (entity, link, pad, interface)
 * is embedded on some other object, this function should be called before
 * registering the object at the media controller.
 */
void media_gobj_create(struct media_device *mdev,
		    enum media_gobj_type type,
		    struct media_gobj *gobj);

/**
 *  media_gobj_destroy - Stop using a graph object on a media device
 *
 * @gobj:	Pointer to the graph object
 *
 * This should be called by all routines like media_device_unregister()
 * that remove/destroy media graph objects.
 */
void media_gobj_destroy(struct media_gobj *gobj);

/**
 * media_entity_pads_init() - Initialize the entity pads
 *
 * @entity:	entity where the pads belong
 * @num_pads:	total number of sink and source pads
 * @pads:	Array of @num_pads pads.
 *
 * The pads array is managed by the entity driver and passed to
 * media_entity_pads_init() where its pointer will be stored in the entity
 * structure.
 *
 * If no pads are needed, drivers could either directly fill
 * &media_entity->@num_pads with 0 and &media_entity->@pads with NULL or call
 * this function that will do the same.
 *
 * As the number of pads is known in advance, the pads array is not allocated
 * dynamically but is managed by the entity driver. Most drivers will embed the
 * pads array in a driver-specific structure, avoiding dynamic allocation.
 *
 * Drivers must set the direction of every pad in the pads array before calling
 * media_entity_pads_init(). The function will initialize the other pads fields.
 */
int media_entity_pads_init(struct media_entity *entity, u16 num_pads,
		      struct media_pad *pads);

/**
 * media_entity_cleanup() - free resources associated with an entity
 *
 * @entity:	entity where the pads belong
 *
 * This function must be called during the cleanup phase after unregistering
 * the entity (currently, it does nothing).
 */
static inline void media_entity_cleanup(struct media_entity *entity) {};

/**
 * media_create_pad_link() - creates a link between two entities.
 *
 * @source:	pointer to &media_entity of the source pad.
 * @source_pad:	number of the source pad in the pads array
 * @sink:	pointer to &media_entity of the sink pad.
 * @sink_pad:	number of the sink pad in the pads array.
 * @flags:	Link flags, as defined in include/uapi/linux/media.h.
 *
 * Valid values for flags:
 * A %MEDIA_LNK_FL_ENABLED flag indicates that the link is enabled and can be
 *	used to transfer media data. When two or more links target a sink pad,
 *	only one of them can be enabled at a time.
 *
 * A %MEDIA_LNK_FL_IMMUTABLE flag indicates that the link enabled state can't
 *	be modified at runtime. If %MEDIA_LNK_FL_IMMUTABLE is set, then
 *	%MEDIA_LNK_FL_ENABLED must also be set since an immutable link is
 *	always enabled.
 *
 * NOTE:
 *
 * Before calling this function, media_entity_pads_init() and
 * media_device_register_entity() should be called previously for both ends.
 */
__must_check int media_create_pad_link(struct media_entity *source,
			u16 source_pad, struct media_entity *sink,
			u16 sink_pad, u32 flags);

/**
 * media_create_pad_links() - creates a link between two entities.
 *
 * @mdev: Pointer to the media_device that contains the object
 * @source_function: Function of the source entities. Used only if @source is
 *	NULL.
 * @source: pointer to &media_entity of the source pad. If NULL, it will use
 * 	all entities that matches the @sink_function.
 * @source_pad: number of the source pad in the pads array
 * @sink_function: Function of the sink entities. Used only if @sink is NULL.
 * @sink: pointer to &media_entity of the sink pad. If NULL, it will use
 * 	all entities that matches the @sink_function.
 * @sink_pad: number of the sink pad in the pads array.
 * @flags: Link flags, as defined in include/uapi/linux/media.h.
 * @allow_both_undefined: if true, then both @source and @sink can be NULL.
 *	In such case, it will create a crossbar between all entities that
 *	matches @source_function to all entities that matches @sink_function.
 *	If false, it will return 0 and won't create any link if both @source
 *	and @sink are NULL.
 *
 * Valid values for flags:
 * A %MEDIA_LNK_FL_ENABLED flag indicates that the link is enabled and can be
 *	used to transfer media data. If multiple links are created and this
 *	flag is passed as an argument, only the first created link will have
 *	this flag.
 *
 * A %MEDIA_LNK_FL_IMMUTABLE flag indicates that the link enabled state can't
 *	be modified at runtime. If %MEDIA_LNK_FL_IMMUTABLE is set, then
 *	%MEDIA_LNK_FL_ENABLED must also be set since an immutable link is
 *	always enabled.
 *
 * It is common for some devices to have multiple source and/or sink entities
 * of the same type that should be linked. While media_create_pad_link()
 * creates link by link, this function is meant to allow 1:n, n:1 and even
 * cross-bar (n:n) links.
 *
 * NOTE: Before calling this function, media_entity_pads_init() and
 * media_device_register_entity() should be called previously for the entities
 * to be linked.
 */
int media_create_pad_links(const struct media_device *mdev,
			   const u32 source_function,
			   struct media_entity *source,
			   const u16 source_pad,
			   const u32 sink_function,
			   struct media_entity *sink,
			   const u16 sink_pad,
			   u32 flags,
			   const bool allow_both_undefined);

void __media_entity_remove_links(struct media_entity *entity);

/**
 * media_entity_remove_links() - remove all links associated with an entity
 *
 * @entity:	pointer to &media_entity
 *
 * Note: this is called automatically when an entity is unregistered via
 * media_device_register_entity().
 */
void media_entity_remove_links(struct media_entity *entity);

/**
 * __media_entity_setup_link - Configure a media link without locking
 * @link: The link being configured
 * @flags: Link configuration flags
 *
 * The bulk of link setup is handled by the two entities connected through the
 * link. This function notifies both entities of the link configuration change.
 *
 * If the link is immutable or if the current and new configuration are
 * identical, return immediately.
 *
 * The user is expected to hold link->source->parent->mutex. If not,
 * media_entity_setup_link() should be used instead.
 */
int __media_entity_setup_link(struct media_link *link, u32 flags);

/**
 * media_entity_setup_link() - changes the link flags properties in runtime
 *
 * @link:	pointer to &media_link
 * @flags:	the requested new link flags
 *
 * The only configurable property is the %MEDIA_LNK_FL_ENABLED link flag
 * flag to enable/disable a link. Links marked with the
 * %MEDIA_LNK_FL_IMMUTABLE link flag can not be enabled or disabled.
 *
 * When a link is enabled or disabled, the media framework calls the
 * link_setup operation for the two entities at the source and sink of the
 * link, in that order. If the second link_setup call fails, another
 * link_setup call is made on the first entity to restore the original link
 * flags.
 *
 * Media device drivers can be notified of link setup operations by setting the
 * media_device::link_notify pointer to a callback function. If provided, the
 * notification callback will be called before enabling and after disabling
 * links.
 *
 * Entity drivers must implement the link_setup operation if any of their links
 * is non-immutable. The operation must either configure the hardware or store
 * the configuration information to be applied later.
 *
 * Link configuration must not have any side effect on other links. If an
 * enabled link at a sink pad prevents another link at the same pad from
 * being enabled, the link_setup operation must return -EBUSY and can't
 * implicitly disable the first enabled link.
 *
 * NOTE: the valid values of the flags for the link is the same as described
 * on media_create_pad_link(), for pad to pad links or the same as described
 * on media_create_intf_link(), for interface to entity links.
 */
int media_entity_setup_link(struct media_link *link, u32 flags);

/**
 * media_entity_find_link - Find a link between two pads
 * @source: Source pad
 * @sink: Sink pad
 *
 * Return a pointer to the link between the two entities. If no such link
 * exists, return NULL.
 */
struct media_link *media_entity_find_link(struct media_pad *source,
		struct media_pad *sink);

/**
 * media_entity_remote_pad - Find the pad at the remote end of a link
 * @pad: Pad at the local end of the link
 *
 * Search for a remote pad connected to the given pad by iterating over all
 * links originating or terminating at that pad until an enabled link is found.
 *
 * Return a pointer to the pad at the remote end of the first found enabled
 * link, or NULL if no enabled link has been found.
 */
struct media_pad *media_entity_remote_pad(struct media_pad *pad);

/**
 * media_entity_get - Get a reference to the parent module
 *
 * @entity: The entity
 *
 * Get a reference to the parent media device module.
 *
 * The function will return immediately if @entity is NULL.
 *
 * Return a pointer to the entity on success or NULL on failure.
 */
struct media_entity *media_entity_get(struct media_entity *entity);

__must_check int media_entity_graph_walk_init(
	struct media_entity_graph *graph, struct media_device *mdev);

/**
 * media_entity_graph_walk_cleanup - Release resources used by graph walk.
 *
 * @graph: Media graph structure that will be used to walk the graph
 */
void media_entity_graph_walk_cleanup(struct media_entity_graph *graph);

/**
 * media_entity_put - Release the reference to the parent module
 *
 * @entity: The entity
 *
 * Release the reference count acquired by media_entity_get().
 *
 * The function will return immediately if @entity is NULL.
 */
void media_entity_put(struct media_entity *entity);

/**
 * media_entity_graph_walk_start - Start walking the media graph at a given entity
 * @graph: Media graph structure that will be used to walk the graph
 * @entity: Starting entity
 *
 * Before using this function, media_entity_graph_walk_init() must be
 * used to allocate resources used for walking the graph. This
 * function initializes the graph traversal structure to walk the
 * entities graph starting at the given entity. The traversal
 * structure must not be modified by the caller during graph
 * traversal. After the graph walk, the resources must be released
 * using media_entity_graph_walk_cleanup().
 */
void media_entity_graph_walk_start(struct media_entity_graph *graph,
				   struct media_entity *entity);

/**
 * media_entity_graph_walk_next - Get the next entity in the graph
 * @graph: Media graph structure
 *
 * Perform a depth-first traversal of the given media entities graph.
 *
 * The graph structure must have been previously initialized with a call to
 * media_entity_graph_walk_start().
 *
 * Return the next entity in the graph or NULL if the whole graph have been
 * traversed.
 */
struct media_entity *
media_entity_graph_walk_next(struct media_entity_graph *graph);

/**
 * media_entity_pipeline_start - Mark a pipeline as streaming
 * @entity: Starting entity
 * @pipe: Media pipeline to be assigned to all entities in the pipeline.
 *
 * Mark all entities connected to a given entity through enabled links, either
 * directly or indirectly, as streaming. The given pipeline object is assigned to
 * every entity in the pipeline and stored in the media_entity pipe field.
 *
 * Calls to this function can be nested, in which case the same number of
 * media_entity_pipeline_stop() calls will be required to stop streaming. The
 * pipeline pointer must be identical for all nested calls to
 * media_entity_pipeline_start().
 */
__must_check int media_entity_pipeline_start(struct media_entity *entity,
					     struct media_pipeline *pipe);

/**
 * media_entity_pipeline_stop - Mark a pipeline as not streaming
 * @entity: Starting entity
 *
 * Mark all entities connected to a given entity through enabled links, either
 * directly or indirectly, as not streaming. The media_entity pipe field is
 * reset to NULL.
 *
 * If multiple calls to media_entity_pipeline_start() have been made, the same
 * number of calls to this function are required to mark the pipeline as not
 * streaming.
 */
void media_entity_pipeline_stop(struct media_entity *entity);

/**
 * media_devnode_create() - creates and initializes a device node interface
 *
 * @mdev:	pointer to struct &media_device
 * @type:	type of the interface, as given by MEDIA_INTF_T_* macros
 *		as defined in the uapi/media/media.h header.
 * @flags:	Interface flags as defined in uapi/media/media.h.
 * @major:	Device node major number.
 * @minor:	Device node minor number.
 *
 * Return: if succeeded, returns a pointer to the newly allocated
 *	&media_intf_devnode pointer.
 */
struct media_intf_devnode *
__must_check media_devnode_create(struct media_device *mdev,
				  u32 type, u32 flags,
				  u32 major, u32 minor);
/**
 * media_devnode_remove() - removes a device node interface
 *
 * @devnode:	pointer to &media_intf_devnode to be freed.
 *
 * When a device node interface is removed, all links to it are automatically
 * removed.
 */
void media_devnode_remove(struct media_intf_devnode *devnode);
struct media_link *

/**
 * media_create_intf_link() - creates a link between an entity and an interface
 *
 * @entity:	pointer to %media_entity
 * @intf:	pointer to %media_interface
 * @flags:	Link flags, as defined in include/uapi/linux/media.h.
 *
 *
 * Valid values for flags:
 * The %MEDIA_LNK_FL_ENABLED flag indicates that the interface is connected to
 *	the entity hardware. That's the default value for interfaces. An
 *	interface may be disabled if the hardware is busy due to the usage
 *	of some other interface that it is currently controlling the hardware.
 *	A typical example is an hybrid TV device that handle only one type of
 *	stream on a given time. So, when the digital TV is streaming,
 *	the V4L2 interfaces won't be enabled, as such device is not able to
 *	also stream analog TV or radio.
 *
 * Note:
 *
 * Before calling this function, media_devnode_create() should be called for
 * the interface and media_device_register_entity() should be called for the
 * interface that will be part of the link.
 */
__must_check media_create_intf_link(struct media_entity *entity,
				    struct media_interface *intf,
				    u32 flags);
/**
 * __media_remove_intf_link() - remove a single interface link
 *
 * @link:	pointer to &media_link.
 *
 * Note: this is an unlocked version of media_remove_intf_link()
 */
void __media_remove_intf_link(struct media_link *link);

/**
 * media_remove_intf_link() - remove a single interface link
 *
 * @link:	pointer to &media_link.
 *
 * Note: prefer to use this one, instead of __media_remove_intf_link()
 */
void media_remove_intf_link(struct media_link *link);

/**
 * __media_remove_intf_links() - remove all links associated with an interface
 *
 * @intf:	pointer to &media_interface
 *
 * Note: this is an unlocked version of media_remove_intf_links().
 */
void __media_remove_intf_links(struct media_interface *intf);

/**
 * media_remove_intf_links() - remove all links associated with an interface
 *
 * @intf:	pointer to &media_interface
 *
 * Notes:
 *
 * this is called automatically when an entity is unregistered via
 * media_device_register_entity() and by media_devnode_remove().
 *
 * Prefer to use this one, instead of __media_remove_intf_links().
 */
void media_remove_intf_links(struct media_interface *intf);

#define media_entity_call(entity, operation, args...)			\
	(((entity)->ops && (entity)->ops->operation) ?			\
	 (entity)->ops->operation((entity) , ##args) : -ENOIOCTLCMD)

#endif