summaryrefslogtreecommitdiffstats
path: root/include/media/videobuf2-core.h
blob: 955237ac503dccdee73311695b6224984ffd906f (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
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
/*
 * videobuf2-core.h - Video Buffer 2 Core Framework
 *
 * Copyright (C) 2010 Samsung Electronics
 *
 * Author: Pawel Osciak <pawel@osciak.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation.
 */
#ifndef _MEDIA_VIDEOBUF2_CORE_H
#define _MEDIA_VIDEOBUF2_CORE_H

#include <linux/mm_types.h>
#include <linux/mutex.h>
#include <linux/poll.h>
#include <linux/dma-buf.h>
#include <linux/bitops.h>
#include <media/media-request.h>
#include <media/frame_vector.h>

#define VB2_MAX_FRAME	(32)
#define VB2_MAX_PLANES	(8)

/**
 * enum vb2_memory - type of memory model used to make the buffers visible
 *	on userspace.
 *
 * @VB2_MEMORY_UNKNOWN:	Buffer status is unknown or it is not used yet on
 *			userspace.
 * @VB2_MEMORY_MMAP:	The buffers are allocated by the Kernel and it is
 *			memory mapped via mmap() ioctl. This model is
 *			also used when the user is using the buffers via
 *			read() or write() system calls.
 * @VB2_MEMORY_USERPTR:	The buffers was allocated in userspace and it is
 *			memory mapped via mmap() ioctl.
 * @VB2_MEMORY_DMABUF:	The buffers are passed to userspace via DMA buffer.
 */
enum vb2_memory {
	VB2_MEMORY_UNKNOWN	= 0,
	VB2_MEMORY_MMAP		= 1,
	VB2_MEMORY_USERPTR	= 2,
	VB2_MEMORY_DMABUF	= 4,
};

struct vb2_fileio_data;
struct vb2_threadio_data;
struct vb2_buffer;

/**
 * struct vb2_mem_ops - memory handling/memory allocator operations.
 * @alloc:	allocate video memory and, optionally, allocator private data,
 *		return ERR_PTR() on failure or a pointer to allocator private,
 *		per-buffer data on success; the returned private structure
 *		will then be passed as @buf_priv argument to other ops in this
 *		structure. The size argument to this function shall be
 *		*page aligned*.
 * @put:	inform the allocator that the buffer will no longer be used;
 *		usually will result in the allocator freeing the buffer (if
 *		no other users of this buffer are present); the @buf_priv
 *		argument is the allocator private per-buffer structure
 *		previously returned from the alloc callback.
 * @get_dmabuf: acquire userspace memory for a hardware operation; used for
 *		 DMABUF memory types.
 * @get_userptr: acquire userspace memory for a hardware operation; used for
 *		 USERPTR memory types; vaddr is the address passed to the
 *		 videobuf2 layer when queuing a video buffer of USERPTR type;
 *		 should return an allocator private per-buffer structure
 *		 associated with the buffer on success, ERR_PTR() on failure;
 *		 the returned private structure will then be passed as @buf_priv
 *		 argument to other ops in this structure.
 * @put_userptr: inform the allocator that a USERPTR buffer will no longer
 *		 be used.
 * @prepare:	called every time the buffer is passed from userspace to the
 *		driver, useful for cache synchronisation, optional.
 * @finish:	called every time the buffer is passed back from the driver
 *		to the userspace, also optional.
 * @attach_dmabuf: attach a shared &struct dma_buf for a hardware operation;
 *		   used for DMABUF memory types; dev is the alloc device
 *		   dbuf is the shared dma_buf; returns ERR_PTR() on failure;
 *		   allocator private per-buffer structure on success;
 *		   this needs to be used for further accesses to the buffer.
 * @detach_dmabuf: inform the exporter of the buffer that the current DMABUF
 *		   buffer is no longer used; the @buf_priv argument is the
 *		   allocator private per-buffer structure previously returned
 *		   from the attach_dmabuf callback.
 * @map_dmabuf: request for access to the dmabuf from allocator; the allocator
 *		of dmabuf is informed that this driver is going to use the
 *		dmabuf.
 * @unmap_dmabuf: releases access control to the dmabuf - allocator is notified
 *		  that this driver is done using the dmabuf for now.
 * @vaddr:	return a kernel virtual address to a given memory buffer
 *		associated with the passed private structure or NULL if no
 *		such mapping exists.
 * @cookie:	return allocator specific cookie for a given memory buffer
 *		associated with the passed private structure or NULL if not
 *		available.
 * @num_users:	return the current number of users of a memory buffer;
 *		return 1 if the videobuf2 layer (or actually the driver using
 *		it) is the only user.
 * @mmap:	setup a userspace mapping for a given memory buffer under
 *		the provided virtual memory region.
 *
 * Those operations are used by the videobuf2 core to implement the memory
 * handling/memory allocators for each type of supported streaming I/O method.
 *
 * .. note::
 *    #) Required ops for USERPTR types: get_userptr, put_userptr.
 *
 *    #) Required ops for MMAP types: alloc, put, num_users, mmap.
 *
 *    #) Required ops for read/write access types: alloc, put, num_users, vaddr.
 *
 *    #) Required ops for DMABUF types: attach_dmabuf, detach_dmabuf,
 *       map_dmabuf, unmap_dmabuf.
 */
struct vb2_mem_ops {
	void		*(*alloc)(struct vb2_buffer *vb,
				  struct device *dev,
				  unsigned long size);
	void		(*put)(void *buf_priv);
	struct dma_buf *(*get_dmabuf)(struct vb2_buffer *vb,
				      void *buf_priv,
				      unsigned long flags);

	void		*(*get_userptr)(struct vb2_buffer *vb,
					struct device *dev,
					unsigned long vaddr,
					unsigned long size);
	void		(*put_userptr)(void *buf_priv);

	void		(*prepare)(void *buf_priv);
	void		(*finish)(void *buf_priv);

	void		*(*attach_dmabuf)(struct vb2_buffer *vb,
					  struct device *dev,
					  struct dma_buf *dbuf,
					  unsigned long size);
	void		(*detach_dmabuf)(void *buf_priv);
	int		(*map_dmabuf)(void *buf_priv);
	void		(*unmap_dmabuf)(void *buf_priv);

	void		*(*vaddr)(struct vb2_buffer *vb, void *buf_priv);
	void		*(*cookie)(struct vb2_buffer *vb, void *buf_priv);

	unsigned int	(*num_users)(void *buf_priv);

	int		(*mmap)(void *buf_priv, struct vm_area_struct *vma);
};

/**
 * struct vb2_plane - plane information.
 * @mem_priv:	private data with this plane.
 * @dbuf:	dma_buf - shared buffer object.
 * @dbuf_mapped:	flag to show whether dbuf is mapped or not
 * @bytesused:	number of bytes occupied by data in the plane (payload).
 * @length:	size of this plane (NOT the payload) in bytes. The maximum
 *		valid size is MAX_UINT - PAGE_SIZE.
 * @min_length:	minimum required size of this plane (NOT the payload) in bytes.
 *		@length is always greater or equal to @min_length, and like
 *		@length, it is limited to MAX_UINT - PAGE_SIZE.
 * @m:		Union with memtype-specific data.
 * @m.offset:	when memory in the associated struct vb2_buffer is
 *		%VB2_MEMORY_MMAP, equals the offset from the start of
 *		the device memory for this plane (or is a "cookie" that
 *		should be passed to mmap() called on the video node).
 * @m.userptr:	when memory is %VB2_MEMORY_USERPTR, a userspace pointer
 *		pointing to this plane.
 * @m.fd:	when memory is %VB2_MEMORY_DMABUF, a userspace file
 *		descriptor associated with this plane.
 * @data_offset:	offset in the plane to the start of data; usually 0,
 *		unless there is a header in front of the data.
 *
 * Should contain enough information to be able to cover all the fields
 * of &struct v4l2_plane at videodev2.h.
 */
struct vb2_plane {
	void			*mem_priv;
	struct dma_buf		*dbuf;
	unsigned int		dbuf_mapped;
	unsigned int		bytesused;
	unsigned int		length;
	unsigned int		min_length;
	union {
		unsigned int	offset;
		unsigned long	userptr;
		int		fd;
	} m;
	unsigned int		data_offset;
};

/**
 * enum vb2_io_modes - queue access methods.
 * @VB2_MMAP:		driver supports MMAP with streaming API.
 * @VB2_USERPTR:	driver supports USERPTR with streaming API.
 * @VB2_READ:		driver supports read() style access.
 * @VB2_WRITE:		driver supports write() style access.
 * @VB2_DMABUF:		driver supports DMABUF with streaming API.
 */
enum vb2_io_modes {
	VB2_MMAP	= BIT(0),
	VB2_USERPTR	= BIT(1),
	VB2_READ	= BIT(2),
	VB2_WRITE	= BIT(3),
	VB2_DMABUF	= BIT(4),
};

/**
 * enum vb2_buffer_state - current video buffer state.
 * @VB2_BUF_STATE_DEQUEUED:	buffer under userspace control.
 * @VB2_BUF_STATE_IN_REQUEST:	buffer is queued in media request.
 * @VB2_BUF_STATE_PREPARING:	buffer is being prepared in videobuf2.
 * @VB2_BUF_STATE_QUEUED:	buffer queued in videobuf2, but not in driver.
 * @VB2_BUF_STATE_ACTIVE:	buffer queued in driver and possibly used
 *				in a hardware operation.
 * @VB2_BUF_STATE_DONE:		buffer returned from driver to videobuf2, but
 *				not yet dequeued to userspace.
 * @VB2_BUF_STATE_ERROR:	same as above, but the operation on the buffer
 *				has ended with an error, which will be reported
 *				to the userspace when it is dequeued.
 */
enum vb2_buffer_state {
	VB2_BUF_STATE_DEQUEUED,
	VB2_BUF_STATE_IN_REQUEST,
	VB2_BUF_STATE_PREPARING,
	VB2_BUF_STATE_QUEUED,
	VB2_BUF_STATE_ACTIVE,
	VB2_BUF_STATE_DONE,
	VB2_BUF_STATE_ERROR,
};

struct vb2_queue;

/**
 * struct vb2_buffer - represents a video buffer.
 * @vb2_queue:		pointer to &struct vb2_queue with the queue to
 *			which this driver belongs.
 * @index:		id number of the buffer.
 * @type:		buffer type.
 * @memory:		the method, in which the actual data is passed.
 * @num_planes:		number of planes in the buffer
 *			on an internal driver queue.
 * @timestamp:		frame timestamp in ns.
 * @request:		the request this buffer is associated with.
 * @req_obj:		used to bind this buffer to a request. This
 *			request object has a refcount.
 */
struct vb2_buffer {
	struct vb2_queue	*vb2_queue;
	unsigned int		index;
	unsigned int		type;
	unsigned int		memory;
	unsigned int		num_planes;
	u64			timestamp;
	struct media_request	*request;
	struct media_request_object	req_obj;

	/* private: internal use only
	 *
	 * state:		current buffer state; do not change
	 * synced:		this buffer has been synced for DMA, i.e. the
	 *			'prepare' memop was called. It is cleared again
	 *			after the 'finish' memop is called.
	 * prepared:		this buffer has been prepared, i.e. the
	 *			buf_prepare op was called. It is cleared again
	 *			after the 'buf_finish' op is called.
	 * copied_timestamp:	the timestamp of this capture buffer was copied
	 *			from an output buffer.
	 * skip_cache_sync_on_prepare: when set buffer's ->prepare() function
	 *			skips cache sync/invalidation.
	 * skip_cache_sync_on_finish: when set buffer's ->finish() function
	 *			skips cache sync/invalidation.
	 * planes:		per-plane information; do not change
	 * queued_entry:	entry on the queued buffers list, which holds
	 *			all buffers queued from userspace
	 * done_entry:		entry on the list that stores all buffers ready
	 *			to be dequeued to userspace
	 */
	enum vb2_buffer_state	state;
	unsigned int		synced:1;
	unsigned int		prepared:1;
	unsigned int		copied_timestamp:1;
	unsigned int		skip_cache_sync_on_prepare:1;
	unsigned int		skip_cache_sync_on_finish:1;

	struct vb2_plane	planes[VB2_MAX_PLANES];
	struct list_head	queued_entry;
	struct list_head	done_entry;
#ifdef CONFIG_VIDEO_ADV_DEBUG
	/*
	 * Counters for how often these buffer-related ops are
	 * called. Used to check for unbalanced ops.
	 */
	u32		cnt_mem_alloc;
	u32		cnt_mem_put;
	u32		cnt_mem_get_dmabuf;
	u32		cnt_mem_get_userptr;
	u32		cnt_mem_put_userptr;
	u32		cnt_mem_prepare;
	u32		cnt_mem_finish;
	u32		cnt_mem_attach_dmabuf;
	u32		cnt_mem_detach_dmabuf;
	u32		cnt_mem_map_dmabuf;
	u32		cnt_mem_unmap_dmabuf;
	u32		cnt_mem_vaddr;
	u32		cnt_mem_cookie;
	u32		cnt_mem_num_users;
	u32		cnt_mem_mmap;

	u32		cnt_buf_out_validate;
	u32		cnt_buf_init;
	u32		cnt_buf_prepare;
	u32		cnt_buf_finish;
	u32		cnt_buf_cleanup;
	u32		cnt_buf_queue;
	u32		cnt_buf_request_complete;

	/* This counts the number of calls to vb2_buffer_done() */
	u32		cnt_buf_done;
#endif
};

/**
 * struct vb2_ops - driver-specific callbacks.
 *
 * These operations are not called from interrupt context except where
 * mentioned specifically.
 *
 * @queue_setup:	called from VIDIOC_REQBUFS() and VIDIOC_CREATE_BUFS()
 *			handlers before memory allocation. It can be called
 *			twice: if the original number of requested buffers
 *			could not be allocated, then it will be called a
 *			second time with the actually allocated number of
 *			buffers to verify if that is OK.
 *			The driver should return the required number of buffers
 *			in \*num_buffers, the required number of planes per
 *			buffer in \*num_planes, the size of each plane should be
 *			set in the sizes\[\] array and optional per-plane
 *			allocator specific device in the alloc_devs\[\] array.
 *			When called from VIDIOC_REQBUFS(), \*num_planes == 0,
 *			the driver has to use the currently configured format to
 *			determine the plane sizes and \*num_buffers is the total
 *			number of buffers that are being allocated. When called
 *			from VIDIOC_CREATE_BUFS(), \*num_planes != 0 and it
 *			describes the requested number of planes and sizes\[\]
 *			contains the requested plane sizes. In this case
 *			\*num_buffers are being allocated additionally to
 *			the buffers already allocated. If either \*num_planes
 *			or the requested sizes are invalid callback must return %-EINVAL.
 * @wait_prepare:	release any locks taken while calling vb2 functions;
 *			it is called before an ioctl needs to wait for a new
 *			buffer to arrive; required to avoid a deadlock in
 *			blocking access type.
 * @wait_finish:	reacquire all locks released in the previous callback;
 *			required to continue operation after sleeping while
 *			waiting for a new buffer to arrive.
 * @buf_out_validate:	called when the output buffer is prepared or queued
 *			to a request; drivers can use this to validate
 *			userspace-provided information; this is required only
 *			for OUTPUT queues.
 * @buf_init:		called once after allocating a buffer (in MMAP case)
 *			or after acquiring a new USERPTR buffer; drivers may
 *			perform additional buffer-related initialization;
 *			initialization failure (return != 0) will prevent
 *			queue setup from completing successfully; optional.
 * @buf_prepare:	called every time the buffer is queued from userspace
 *			and from the VIDIOC_PREPARE_BUF() ioctl; drivers may
 *			perform any initialization required before each
 *			hardware operation in this callback; drivers can
 *			access/modify the buffer here as it is still synced for
 *			the CPU; drivers that support VIDIOC_CREATE_BUFS() must
 *			also validate the buffer size; if an error is returned,
 *			the buffer will not be queued in driver; optional.
 * @buf_finish:		called before every dequeue of the buffer back to
 *			userspace; the buffer is synced for the CPU, so drivers
 *			can access/modify the buffer contents; drivers may
 *			perform any operations required before userspace
 *			accesses the buffer; optional. The buffer state can be
 *			one of the following: %DONE and %ERROR occur while
 *			streaming is in progress, and the %PREPARED state occurs
 *			when the queue has been canceled and all pending
 *			buffers are being returned to their default %DEQUEUED
 *			state. Typically you only have to do something if the
 *			state is %VB2_BUF_STATE_DONE, since in all other cases
 *			the buffer contents will be ignored anyway.
 * @buf_cleanup:	called once before the buffer is freed; drivers may
 *			perform any additional cleanup; optional.
 * @prepare_streaming:	called once to prepare for 'streaming' state; this is
 *			where validation can be done to verify everything is
 *			okay and streaming resources can be claimed. It is
 *			called when the VIDIOC_STREAMON ioctl is called. The
 *			actual streaming starts when @start_streaming is called.
 *			Optional.
 * @start_streaming:	called once to enter 'streaming' state; the driver may
 *			receive buffers with @buf_queue callback
 *			before @start_streaming is called; the driver gets the
 *			number of already queued buffers in count parameter;
 *			driver can return an error if hardware fails, in that
 *			case all buffers that have been already given by
 *			the @buf_queue callback are to be returned by the driver
 *			by calling vb2_buffer_done() with %VB2_BUF_STATE_QUEUED.
 *			If you need a minimum number of buffers before you can
 *			start streaming, then set
 *			&vb2_queue->min_queued_buffers. If that is non-zero
 *			then @start_streaming won't be called until at least
 *			that many buffers have been queued up by userspace.
 * @stop_streaming:	called when 'streaming' state must be disabled; driver
 *			should stop any DMA transactions or wait until they
 *			finish and give back all buffers it got from &buf_queue
 *			callback by calling vb2_buffer_done() with either
 *			%VB2_BUF_STATE_DONE or %VB2_BUF_STATE_ERROR; may use
 *			vb2_wait_for_all_buffers() function
 * @unprepare_streaming:called as counterpart to @prepare_streaming; any claimed
 *			streaming resources can be released here. It is
 *			called when the VIDIOC_STREAMOFF ioctls is called or
 *			when the streaming filehandle is closed. Optional.
 * @buf_queue:		passes buffer vb to the driver; driver may start
 *			hardware operation on this buffer; driver should give
 *			the buffer back by calling vb2_buffer_done() function;
 *			it is always called after calling VIDIOC_STREAMON()
 *			ioctl; might be called before @start_streaming callback
 *			if user pre-queued buffers before calling
 *			VIDIOC_STREAMON().
 * @buf_request_complete: a buffer that was never queued to the driver but is
 *			associated with a queued request was canceled.
 *			The driver will have to mark associated objects in the
 *			request as completed; required if requests are
 *			supported.
 */
struct vb2_ops {
	int (*queue_setup)(struct vb2_queue *q,
			   unsigned int *num_buffers, unsigned int *num_planes,
			   unsigned int sizes[], struct device *alloc_devs[]);

	void (*wait_prepare)(struct vb2_queue *q);
	void (*wait_finish)(struct vb2_queue *q);

	int (*buf_out_validate)(struct vb2_buffer *vb);
	int (*buf_init)(struct vb2_buffer *vb);
	int (*buf_prepare)(struct vb2_buffer *vb);
	void (*buf_finish)(struct vb2_buffer *vb);
	void (*buf_cleanup)(struct vb2_buffer *vb);

	int (*prepare_streaming)(struct vb2_queue *q);
	int (*start_streaming)(struct vb2_queue *q, unsigned int count);
	void (*stop_streaming)(struct vb2_queue *q);
	void (*unprepare_streaming)(struct vb2_queue *q);

	void (*buf_queue)(struct vb2_buffer *vb);

	void (*buf_request_complete)(struct vb2_buffer *vb);
};

/**
 * struct vb2_buf_ops - driver-specific callbacks.
 *
 * @verify_planes_array: Verify that a given user space structure contains
 *			enough planes for the buffer. This is called
 *			for each dequeued buffer.
 * @init_buffer:	given a &vb2_buffer initialize the extra data after
 *			struct vb2_buffer.
 *			For V4L2 this is a &struct vb2_v4l2_buffer.
 * @fill_user_buffer:	given a &vb2_buffer fill in the userspace structure.
 *			For V4L2 this is a &struct v4l2_buffer.
 * @fill_vb2_buffer:	given a userspace structure, fill in the &vb2_buffer.
 *			If the userspace structure is invalid, then this op
 *			will return an error.
 * @copy_timestamp:	copy the timestamp from a userspace structure to
 *			the &struct vb2_buffer.
 */
struct vb2_buf_ops {
	int (*verify_planes_array)(struct vb2_buffer *vb, const void *pb);
	void (*init_buffer)(struct vb2_buffer *vb);
	void (*fill_user_buffer)(struct vb2_buffer *vb, void *pb);
	int (*fill_vb2_buffer)(struct vb2_buffer *vb, struct vb2_plane *planes);
	void (*copy_timestamp)(struct vb2_buffer *vb, const void *pb);
};

/**
 * struct vb2_queue - a videobuf2 queue.
 *
 * @type:	private buffer type whose content is defined by the vb2-core
 *		caller. For example, for V4L2, it should match
 *		the types defined on &enum v4l2_buf_type.
 * @io_modes:	supported io methods (see &enum vb2_io_modes).
 * @dev:	device to use for the default allocation context if the driver
 *		doesn't fill in the @alloc_devs array.
 * @dma_attrs:	DMA attributes to use for the DMA.
 * @bidirectional: when this flag is set the DMA direction for the buffers of
 *		this queue will be overridden with %DMA_BIDIRECTIONAL direction.
 *		This is useful in cases where the hardware (firmware) writes to
 *		a buffer which is mapped as read (%DMA_TO_DEVICE), or reads from
 *		buffer which is mapped for write (%DMA_FROM_DEVICE) in order
 *		to satisfy some internal hardware restrictions or adds a padding
 *		needed by the processing algorithm. In case the DMA mapping is
 *		not bidirectional but the hardware (firmware) trying to access
 *		the buffer (in the opposite direction) this could lead to an
 *		IOMMU protection faults.
 * @fileio_read_once:		report EOF after reading the first buffer
 * @fileio_write_immediately:	queue buffer after each write() call
 * @allow_zero_bytesused:	allow bytesused == 0 to be passed to the driver
 * @quirk_poll_must_check_waiting_for_buffers: Return %EPOLLERR at poll when QBUF
 *              has not been called. This is a vb1 idiom that has been adopted
 *              also by vb2.
 * @supports_requests: this queue supports the Request API.
 * @requires_requests: this queue requires the Request API. If this is set to 1,
 *		then supports_requests must be set to 1 as well.
 * @uses_qbuf:	qbuf was used directly for this queue. Set to 1 the first
 *		time this is called. Set to 0 when the queue is canceled.
 *		If this is 1, then you cannot queue buffers from a request.
 * @uses_requests: requests are used for this queue. Set to 1 the first time
 *		a request is queued. Set to 0 when the queue is canceled.
 *		If this is 1, then you cannot queue buffers directly.
 * @allow_cache_hints: when set user-space can pass cache management hints in
 *		order to skip cache flush/invalidation on ->prepare() or/and
 *		->finish().
 * @non_coherent_mem: when set queue will attempt to allocate buffers using
 *		non-coherent memory.
 * @lock:	pointer to a mutex that protects the &struct vb2_queue. The
 *		driver can set this to a mutex to let the v4l2 core serialize
 *		the queuing ioctls. If the driver wants to handle locking
 *		itself, then this should be set to NULL. This lock is not used
 *		by the videobuf2 core API.
 * @owner:	The filehandle that 'owns' the buffers, i.e. the filehandle
 *		that called reqbufs, create_buffers or started fileio.
 *		This field is not used by the videobuf2 core API, but it allows
 *		drivers to easily associate an owner filehandle with the queue.
 * @ops:	driver-specific callbacks
 * @mem_ops:	memory allocator specific callbacks
 * @buf_ops:	callbacks to deliver buffer information.
 *		between user-space and kernel-space.
 * @drv_priv:	driver private data.
 * @subsystem_flags: Flags specific to the subsystem (V4L2/DVB/etc.). Not used
 *		by the vb2 core.
 * @buf_struct_size: size of the driver-specific buffer structure;
 *		"0" indicates the driver doesn't want to use a custom buffer
 *		structure type. In that case a subsystem-specific struct
 *		will be used (in the case of V4L2 that is
 *		``sizeof(struct vb2_v4l2_buffer)``). The first field of the
 *		driver-specific buffer structure must be the subsystem-specific
 *		struct (vb2_v4l2_buffer in the case of V4L2).
 * @timestamp_flags: Timestamp flags; ``V4L2_BUF_FLAG_TIMESTAMP_*`` and
 *		``V4L2_BUF_FLAG_TSTAMP_SRC_*``
 * @gfp_flags:	additional gfp flags used when allocating the buffers.
 *		Typically this is 0, but it may be e.g. %GFP_DMA or %__GFP_DMA32
 *		to force the buffer allocation to a specific memory zone.
 * @min_queued_buffers: the minimum number of queued buffers needed before
 *		@start_streaming can be called. Used when a DMA engine
 *		cannot be started unless at least this number of buffers
 *		have been queued into the driver.
 *		VIDIOC_REQBUFS will ensure at least @min_queued_buffers + 1
 *		buffers will be allocated. Note that VIDIOC_CREATE_BUFS will not
 *		modify the requested buffer count.
 * @min_reqbufs_allocation: the minimum number of buffers to be allocated when
 *		calling VIDIOC_REQBUFS. Note that VIDIOC_CREATE_BUFS will *not*
 *		modify the requested buffer count and does not use this field.
 *		Drivers can set this if there has to be a certain number of
 *		buffers available for the hardware to work effectively.
 *		This allows calling VIDIOC_REQBUFS with a buffer count of 1 and
 *		it will be automatically adjusted to a workable	buffer count.
 *		If set, then @min_reqbufs_allocation must be larger than
 *		@min_queued_buffers + 1.
 *		If this field is > 3, then it is highly recommended that the
 *		driver implements the V4L2_CID_MIN_BUFFERS_FOR_CAPTURE/OUTPUT
 *		control.
 * @alloc_devs:	&struct device memory type/allocator-specific per-plane device
 */
/*
 * Private elements (won't appear at the uAPI book):
 * @mmap_lock:	private mutex used when buffers are allocated/freed/mmapped
 * @memory:	current memory type used
 * @dma_dir:	DMA mapping direction.
 * @bufs:	videobuf2 buffer structures. If it is non-NULL then
 *		bufs_bitmap is also non-NULL.
 * @bufs_bitmap: bitmap tracking whether each bufs[] entry is used
 * @max_num_buffers: upper limit of number of allocated/used buffers.
 *		     If set to 0 v4l2 core will change it VB2_MAX_FRAME
 *		     for backward compatibility.
 * @queued_list: list of buffers currently queued from userspace
 * @queued_count: number of buffers queued and ready for streaming.
 * @owned_by_drv_count: number of buffers owned by the driver
 * @done_list:	list of buffers ready to be dequeued to userspace
 * @done_lock:	lock to protect done_list list
 * @done_wq:	waitqueue for processes waiting for buffers ready to be dequeued
 * @streaming:	current streaming state
 * @start_streaming_called: @start_streaming was called successfully and we
 *		started streaming.
 * @error:	a fatal error occurred on the queue
 * @waiting_for_buffers: used in poll() to check if vb2 is still waiting for
 *		buffers. Only set for capture queues if qbuf has not yet been
 *		called since poll() needs to return %EPOLLERR in that situation.
 * @waiting_in_dqbuf: set by the core for the duration of a blocking DQBUF, when
 *		it has to wait for a buffer to become available with vb2_queue->lock
 *		released. Used to prevent destroying the queue by other threads.
 * @is_multiplanar: set if buffer type is multiplanar
 * @is_output:	set if buffer type is output
 * @is_busy:	set if at least one buffer has been allocated at some time.
 * @copy_timestamp: set if vb2-core should set timestamps
 * @last_buffer_dequeued: used in poll() and DQBUF to immediately return if the
 *		last decoded buffer was already dequeued. Set for capture queues
 *		when a buffer with the %V4L2_BUF_FLAG_LAST is dequeued.
 * @fileio:	file io emulator internal data, used only if emulator is active
 * @threadio:	thread io internal data, used only if thread is active
 * @name:	queue name, used for logging purpose. Initialized automatically
 *		if left empty by drivers.
 */
struct vb2_queue {
	unsigned int			type;
	unsigned int			io_modes;
	struct device			*dev;
	unsigned long			dma_attrs;
	unsigned int			bidirectional:1;
	unsigned int			fileio_read_once:1;
	unsigned int			fileio_write_immediately:1;
	unsigned int			allow_zero_bytesused:1;
	unsigned int		   quirk_poll_must_check_waiting_for_buffers:1;
	unsigned int			supports_requests:1;
	unsigned int			requires_requests:1;
	unsigned int			uses_qbuf:1;
	unsigned int			uses_requests:1;
	unsigned int			allow_cache_hints:1;
	unsigned int			non_coherent_mem:1;

	struct mutex			*lock;
	void				*owner;

	const struct vb2_ops		*ops;
	const struct vb2_mem_ops	*mem_ops;
	const struct vb2_buf_ops	*buf_ops;

	void				*drv_priv;
	u32				subsystem_flags;
	unsigned int			buf_struct_size;
	u32				timestamp_flags;
	gfp_t				gfp_flags;
	u32				min_queued_buffers;
	u32				min_reqbufs_allocation;

	struct device			*alloc_devs[VB2_MAX_PLANES];

	/* private: internal use only */
	struct mutex			mmap_lock;
	unsigned int			memory;
	enum dma_data_direction		dma_dir;
	struct vb2_buffer		**bufs;
	unsigned long			*bufs_bitmap;
	unsigned int			max_num_buffers;

	struct list_head		queued_list;
	unsigned int			queued_count;

	atomic_t			owned_by_drv_count;
	struct list_head		done_list;
	spinlock_t			done_lock;
	wait_queue_head_t		done_wq;

	unsigned int			streaming:1;
	unsigned int			start_streaming_called:1;
	unsigned int			error:1;
	unsigned int			waiting_for_buffers:1;
	unsigned int			waiting_in_dqbuf:1;
	unsigned int			is_multiplanar:1;
	unsigned int			is_output:1;
	unsigned int			is_busy:1;
	unsigned int			copy_timestamp:1;
	unsigned int			last_buffer_dequeued:1;

	struct vb2_fileio_data		*fileio;
	struct vb2_threadio_data	*threadio;

	char				name[32];

#ifdef CONFIG_VIDEO_ADV_DEBUG
	/*
	 * Counters for how often these queue-related ops are
	 * called. Used to check for unbalanced ops.
	 */
	u32				cnt_queue_setup;
	u32				cnt_wait_prepare;
	u32				cnt_wait_finish;
	u32				cnt_prepare_streaming;
	u32				cnt_start_streaming;
	u32				cnt_stop_streaming;
	u32				cnt_unprepare_streaming;
#endif
};

/**
 * vb2_queue_allows_cache_hints() - Return true if the queue allows cache
 * and memory consistency hints.
 *
 * @q:		pointer to &struct vb2_queue with videobuf2 queue
 */
static inline bool vb2_queue_allows_cache_hints(struct vb2_queue *q)
{
	return q->allow_cache_hints && q->memory == VB2_MEMORY_MMAP;
}

/**
 * vb2_plane_vaddr() - Return a kernel virtual address of a given plane.
 * @vb:		pointer to &struct vb2_buffer to which the plane in
 *		question belongs to.
 * @plane_no:	plane number for which the address is to be returned.
 *
 * This function returns a kernel virtual address of a given plane if
 * such a mapping exist, NULL otherwise.
 */
void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no);

/**
 * vb2_plane_cookie() - Return allocator specific cookie for the given plane.
 * @vb:		pointer to &struct vb2_buffer to which the plane in
 *		question belongs to.
 * @plane_no:	plane number for which the cookie is to be returned.
 *
 * This function returns an allocator specific cookie for a given plane if
 * available, NULL otherwise. The allocator should provide some simple static
 * inline function, which would convert this cookie to the allocator specific
 * type that can be used directly by the driver to access the buffer. This can
 * be for example physical address, pointer to scatter list or IOMMU mapping.
 */
void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no);

/**
 * vb2_buffer_done() - inform videobuf2 that an operation on a buffer
 *	is finished.
 * @vb:		pointer to &struct vb2_buffer to be used.
 * @state:	state of the buffer, as defined by &enum vb2_buffer_state.
 *		Either %VB2_BUF_STATE_DONE if the operation finished
 *		successfully, %VB2_BUF_STATE_ERROR if the operation finished
 *		with an error or %VB2_BUF_STATE_QUEUED.
 *
 * This function should be called by the driver after a hardware operation on
 * a buffer is finished and the buffer may be returned to userspace. The driver
 * cannot use this buffer anymore until it is queued back to it by videobuf
 * by the means of &vb2_ops->buf_queue callback. Only buffers previously queued
 * to the driver by &vb2_ops->buf_queue can be passed to this function.
 *
 * While streaming a buffer can only be returned in state DONE or ERROR.
 * The &vb2_ops->start_streaming op can also return them in case the DMA engine
 * cannot be started for some reason. In that case the buffers should be
 * returned with state QUEUED to put them back into the queue.
 */
void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state);

/**
 * vb2_discard_done() - discard all buffers marked as DONE.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 *
 * This function is intended to be used with suspend/resume operations. It
 * discards all 'done' buffers as they would be too old to be requested after
 * resume.
 *
 * Drivers must stop the hardware and synchronize with interrupt handlers and/or
 * delayed works before calling this function to make sure no buffer will be
 * touched by the driver and/or hardware.
 */
void vb2_discard_done(struct vb2_queue *q);

/**
 * vb2_wait_for_all_buffers() - wait until all buffers are given back to vb2.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 *
 * This function will wait until all buffers that have been given to the driver
 * by &vb2_ops->buf_queue are given back to vb2 with vb2_buffer_done(). It
 * doesn't call &vb2_ops->wait_prepare/&vb2_ops->wait_finish pair.
 * It is intended to be called with all locks taken, for example from
 * &vb2_ops->stop_streaming callback.
 */
int vb2_wait_for_all_buffers(struct vb2_queue *q);

/**
 * vb2_core_querybuf() - query video buffer information.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 * @vb:		pointer to struct &vb2_buffer.
 * @pb:		buffer struct passed from userspace.
 *
 * Videobuf2 core helper to implement VIDIOC_QUERYBUF() operation. It is called
 * internally by VB2 by an API-specific handler, like ``videobuf2-v4l2.h``.
 *
 * The passed buffer should have been verified.
 *
 * This function fills the relevant information for the userspace.
 *
 * Return: returns zero on success; an error code otherwise.
 */
void vb2_core_querybuf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb);

/**
 * vb2_core_reqbufs() - Initiate streaming.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 * @memory:	memory type, as defined by &enum vb2_memory.
 * @flags:	auxiliary queue/buffer management flags. Currently, the only
 *		used flag is %V4L2_MEMORY_FLAG_NON_COHERENT.
 * @count:	requested buffer count.
 *
 * Videobuf2 core helper to implement VIDIOC_REQBUF() operation. It is called
 * internally by VB2 by an API-specific handler, like ``videobuf2-v4l2.h``.
 *
 * This function:
 *
 * #) verifies streaming parameters passed from the userspace;
 * #) sets up the queue;
 * #) negotiates number of buffers and planes per buffer with the driver
 *    to be used during streaming;
 * #) allocates internal buffer structures (&struct vb2_buffer), according to
 *    the agreed parameters;
 * #) for MMAP memory type, allocates actual video memory, using the
 *    memory handling/allocation routines provided during queue initialization.
 *
 * If req->count is 0, all the memory will be freed instead.
 *
 * If the queue has been allocated previously by a previous vb2_core_reqbufs()
 * call and the queue is not busy, memory will be reallocated.
 *
 * Return: returns zero on success; an error code otherwise.
 */
int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
		     unsigned int flags, unsigned int *count);

/**
 * vb2_core_create_bufs() - Allocate buffers and any required auxiliary structs
 * @q: pointer to &struct vb2_queue with videobuf2 queue.
 * @memory: memory type, as defined by &enum vb2_memory.
 * @flags: auxiliary queue/buffer management flags.
 * @count: requested buffer count.
 * @requested_planes: number of planes requested.
 * @requested_sizes: array with the size of the planes.
 * @first_index: index of the first created buffer, all allocated buffers have
 *		 indices in the range [first_index..first_index+count-1]
 *
 * Videobuf2 core helper to implement VIDIOC_CREATE_BUFS() operation. It is
 * called internally by VB2 by an API-specific handler, like
 * ``videobuf2-v4l2.h``.
 *
 * This function:
 *
 * #) verifies parameter sanity;
 * #) calls the &vb2_ops->queue_setup queue operation;
 * #) performs any necessary memory allocations.
 *
 * Return: returns zero on success; an error code otherwise.
 */
int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
			 unsigned int flags, unsigned int *count,
			 unsigned int requested_planes,
			 const unsigned int requested_sizes[],
			 unsigned int *first_index);

/**
 * vb2_core_prepare_buf() - Pass ownership of a buffer from userspace
 *			to the kernel.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 * @vb:		pointer to struct &vb2_buffer.
 * @pb:		buffer structure passed from userspace to
 *		&v4l2_ioctl_ops->vidioc_prepare_buf handler in driver.
 *
 * Videobuf2 core helper to implement VIDIOC_PREPARE_BUF() operation. It is
 * called internally by VB2 by an API-specific handler, like
 * ``videobuf2-v4l2.h``.
 *
 * The passed buffer should have been verified.
 *
 * This function calls vb2_ops->buf_prepare callback in the driver
 * (if provided), in which driver-specific buffer initialization can
 * be performed.
 *
 * Return: returns zero on success; an error code otherwise.
 */
int vb2_core_prepare_buf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb);

/**
 * vb2_core_remove_bufs() -
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 * @start:	first index of the range of buffers to remove.
 * @count:	number of buffers to remove.
 *
 *  Return: returns zero on success; an error code otherwise.
 */
int vb2_core_remove_bufs(struct vb2_queue *q, unsigned int start, unsigned int count);

/**
 * vb2_core_qbuf() - Queue a buffer from userspace
 *
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 * @vb:		pointer to struct &vb2_buffer.
 * @pb:		buffer structure passed from userspace to
 *		v4l2_ioctl_ops->vidioc_qbuf handler in driver
 * @req:	pointer to &struct media_request, may be NULL.
 *
 * Videobuf2 core helper to implement VIDIOC_QBUF() operation. It is called
 * internally by VB2 by an API-specific handler, like ``videobuf2-v4l2.h``.
 *
 * This function:
 *
 * #) If @req is non-NULL, then the buffer will be bound to this
 *    media request and it returns. The buffer will be prepared and
 *    queued to the driver (i.e. the next two steps) when the request
 *    itself is queued.
 * #) if necessary, calls &vb2_ops->buf_prepare callback in the driver
 *    (if provided), in which driver-specific buffer initialization can
 *    be performed;
 * #) if streaming is on, queues the buffer in driver by the means of
 *    &vb2_ops->buf_queue callback for processing.
 *
 * Return: returns zero on success; an error code otherwise.
 */
int vb2_core_qbuf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb,
		  struct media_request *req);

/**
 * vb2_core_dqbuf() - Dequeue a buffer to the userspace
 * @q:		pointer to &struct vb2_queue with videobuf2 queue
 * @pindex:	pointer to the buffer index. May be NULL
 * @pb:		buffer structure passed from userspace to
 *		v4l2_ioctl_ops->vidioc_dqbuf handler in driver.
 * @nonblocking: if true, this call will not sleep waiting for a buffer if no
 *		 buffers ready for dequeuing are present. Normally the driver
 *		 would be passing (file->f_flags & O_NONBLOCK) here.
 *
 * Videobuf2 core helper to implement VIDIOC_DQBUF() operation. It is called
 * internally by VB2 by an API-specific handler, like ``videobuf2-v4l2.h``.
 *
 * This function:
 *
 * #) calls buf_finish callback in the driver (if provided), in which
 *    driver can perform any additional operations that may be required before
 *    returning the buffer to userspace, such as cache sync,
 * #) the buffer struct members are filled with relevant information for
 *    the userspace.
 *
 * Return: returns zero on success; an error code otherwise.
 */
int vb2_core_dqbuf(struct vb2_queue *q, unsigned int *pindex, void *pb,
		   bool nonblocking);

/**
 * vb2_core_streamon() - Implements VB2 stream ON logic
 *
 * @q:		pointer to &struct vb2_queue with videobuf2 queue
 * @type:	type of the queue to be started.
 *		For V4L2, this is defined by &enum v4l2_buf_type type.
 *
 * Videobuf2 core helper to implement VIDIOC_STREAMON() operation. It is called
 * internally by VB2 by an API-specific handler, like ``videobuf2-v4l2.h``.
 *
 * Return: returns zero on success; an error code otherwise.
 */
int vb2_core_streamon(struct vb2_queue *q, unsigned int type);

/**
 * vb2_core_streamoff() - Implements VB2 stream OFF logic
 *
 * @q:		pointer to &struct vb2_queue with videobuf2 queue
 * @type:	type of the queue to be started.
 *		For V4L2, this is defined by &enum v4l2_buf_type type.
 *
 * Videobuf2 core helper to implement VIDIOC_STREAMOFF() operation. It is
 * called internally by VB2 by an API-specific handler, like
 * ``videobuf2-v4l2.h``.
 *
 * Return: returns zero on success; an error code otherwise.
 */
int vb2_core_streamoff(struct vb2_queue *q, unsigned int type);

/**
 * vb2_core_expbuf() - Export a buffer as a file descriptor.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 * @fd:		pointer to the file descriptor associated with DMABUF
 *		(set by driver).
 * @type:	buffer type.
 * @vb:		pointer to struct &vb2_buffer.
 * @plane:	index of the plane to be exported, 0 for single plane queues
 * @flags:	file flags for newly created file, as defined at
 *		include/uapi/asm-generic/fcntl.h.
 *		Currently, the only used flag is %O_CLOEXEC.
 *		is supported, refer to manual of open syscall for more details.
 *
 *
 * Videobuf2 core helper to implement VIDIOC_EXPBUF() operation. It is called
 * internally by VB2 by an API-specific handler, like ``videobuf2-v4l2.h``.
 *
 * Return: returns zero on success; an error code otherwise.
 */
int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type,
		    struct vb2_buffer *vb, unsigned int plane, unsigned int flags);

/**
 * vb2_core_queue_init() - initialize a videobuf2 queue
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 *		This structure should be allocated in driver
 *
 * The &vb2_queue structure should be allocated by the driver. The driver is
 * responsible of clearing it's content and setting initial values for some
 * required entries before calling this function.
 *
 * .. note::
 *
 *    The following fields at @q should be set before calling this function:
 *    &vb2_queue->ops, &vb2_queue->mem_ops, &vb2_queue->type.
 */
int vb2_core_queue_init(struct vb2_queue *q);

/**
 * vb2_core_queue_release() - stop streaming, release the queue and free memory
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 *
 * This function stops streaming and performs necessary clean ups, including
 * freeing video buffer memory. The driver is responsible for freeing
 * the &struct vb2_queue itself.
 */
void vb2_core_queue_release(struct vb2_queue *q);

/**
 * vb2_queue_error() - signal a fatal error on the queue
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 *
 * Flag that a fatal unrecoverable error has occurred and wake up all processes
 * waiting on the queue. Polling will now set %EPOLLERR and queuing and dequeuing
 * buffers will return %-EIO.
 *
 * The error flag will be cleared when canceling the queue, either from
 * vb2_streamoff() or vb2_queue_release(). Drivers should thus not call this
 * function before starting the stream, otherwise the error flag will remain set
 * until the queue is released when closing the device node.
 */
void vb2_queue_error(struct vb2_queue *q);

/**
 * vb2_mmap() - map video buffers into application address space.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 * @vma:	pointer to &struct vm_area_struct with the vma passed
 *		to the mmap file operation handler in the driver.
 *
 * Should be called from mmap file operation handler of a driver.
 * This function maps one plane of one of the available video buffers to
 * userspace. To map whole video memory allocated on reqbufs, this function
 * has to be called once per each plane per each buffer previously allocated.
 *
 * When the userspace application calls mmap, it passes to it an offset returned
 * to it earlier by the means of &v4l2_ioctl_ops->vidioc_querybuf handler.
 * That offset acts as a "cookie", which is then used to identify the plane
 * to be mapped.
 *
 * This function finds a plane with a matching offset and a mapping is performed
 * by the means of a provided memory operation.
 *
 * The return values from this function are intended to be directly returned
 * from the mmap handler in driver.
 */
int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma);

#ifndef CONFIG_MMU
/**
 * vb2_get_unmapped_area - map video buffers into application address space.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 * @addr:	memory address.
 * @len:	buffer size.
 * @pgoff:	page offset.
 * @flags:	memory flags.
 *
 * This function is used in noMMU platforms to propose address mapping
 * for a given buffer. It's intended to be used as a handler for the
 * &file_operations->get_unmapped_area operation.
 *
 * This is called by the mmap() syscall routines will call this
 * to get a proposed address for the mapping, when ``!CONFIG_MMU``.
 */
unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
				    unsigned long addr,
				    unsigned long len,
				    unsigned long pgoff,
				    unsigned long flags);
#endif

/**
 * vb2_core_poll() - implements poll syscall() logic.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 * @file:	&struct file argument passed to the poll
 *		file operation handler.
 * @wait:	&poll_table wait argument passed to the poll
 *		file operation handler.
 *
 * This function implements poll file operation handler for a driver.
 * For CAPTURE queues, if a buffer is ready to be dequeued, the userspace will
 * be informed that the file descriptor of a video device is available for
 * reading.
 * For OUTPUT queues, if a buffer is ready to be dequeued, the file descriptor
 * will be reported as available for writing.
 *
 * The return values from this function are intended to be directly returned
 * from poll handler in driver.
 */
__poll_t vb2_core_poll(struct vb2_queue *q, struct file *file,
			   poll_table *wait);

/**
 * vb2_read() - implements read() syscall logic.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 * @data:	pointed to target userspace buffer
 * @count:	number of bytes to read
 * @ppos:	file handle position tracking pointer
 * @nonblock:	mode selector (1 means blocking calls, 0 means nonblocking)
 */
size_t vb2_read(struct vb2_queue *q, char __user *data, size_t count,
		loff_t *ppos, int nonblock);
/**
 * vb2_write() - implements write() syscall logic.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 * @data:	pointed to target userspace buffer
 * @count:	number of bytes to write
 * @ppos:	file handle position tracking pointer
 * @nonblock:	mode selector (1 means blocking calls, 0 means nonblocking)
 */
size_t vb2_write(struct vb2_queue *q, const char __user *data, size_t count,
		loff_t *ppos, int nonblock);

/**
 * typedef vb2_thread_fnc - callback function for use with vb2_thread.
 *
 * @vb: pointer to struct &vb2_buffer.
 * @priv: pointer to a private data.
 *
 * This is called whenever a buffer is dequeued in the thread.
 */
typedef int (*vb2_thread_fnc)(struct vb2_buffer *vb, void *priv);

/**
 * vb2_thread_start() - start a thread for the given queue.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 * @fnc:	&vb2_thread_fnc callback function.
 * @priv:	priv pointer passed to the callback function.
 * @thread_name:the name of the thread. This will be prefixed with "vb2-".
 *
 * This starts a thread that will queue and dequeue until an error occurs
 * or vb2_thread_stop() is called.
 *
 * .. attention::
 *
 *   This function should not be used for anything else but the videobuf2-dvb
 *   support. If you think you have another good use-case for this, then please
 *   contact the linux-media mailing list first.
 */
int vb2_thread_start(struct vb2_queue *q, vb2_thread_fnc fnc, void *priv,
		     const char *thread_name);

/**
 * vb2_thread_stop() - stop the thread for the given queue.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 */
int vb2_thread_stop(struct vb2_queue *q);

/**
 * vb2_is_streaming() - return streaming status of the queue.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 */
static inline bool vb2_is_streaming(struct vb2_queue *q)
{
	return q->streaming;
}

/**
 * vb2_fileio_is_active() - return true if fileio is active.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 *
 * This returns true if read() or write() is used to stream the data
 * as opposed to stream I/O. This is almost never an important distinction,
 * except in rare cases. One such case is that using read() or write() to
 * stream a format using %V4L2_FIELD_ALTERNATE is not allowed since there
 * is no way you can pass the field information of each buffer to/from
 * userspace. A driver that supports this field format should check for
 * this in the &vb2_ops->queue_setup op and reject it if this function returns
 * true.
 */
static inline bool vb2_fileio_is_active(struct vb2_queue *q)
{
	return q->fileio;
}

/**
 * vb2_get_num_buffers() - get the number of buffer in a queue
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 */
static inline unsigned int vb2_get_num_buffers(struct vb2_queue *q)
{
	if (q->bufs_bitmap)
		return bitmap_weight(q->bufs_bitmap, q->max_num_buffers);

	return 0;
}

/**
 * vb2_is_busy() - return busy status of the queue.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 *
 * This function checks if queue has any buffers allocated.
 */
static inline bool vb2_is_busy(struct vb2_queue *q)
{
	return !!q->is_busy;
}

/**
 * vb2_get_drv_priv() - return driver private data associated with the queue.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 */
static inline void *vb2_get_drv_priv(struct vb2_queue *q)
{
	return q->drv_priv;
}

/**
 * vb2_set_plane_payload() - set bytesused for the plane @plane_no.
 * @vb:		pointer to &struct vb2_buffer to which the plane in
 *		question belongs to.
 * @plane_no:	plane number for which payload should be set.
 * @size:	payload in bytes.
 */
static inline void vb2_set_plane_payload(struct vb2_buffer *vb,
				 unsigned int plane_no, unsigned long size)
{
	/*
	 * size must never be larger than the buffer length, so
	 * warn and clamp to the buffer length if that's the case.
	 */
	if (plane_no < vb->num_planes) {
		if (WARN_ON_ONCE(size > vb->planes[plane_no].length))
			size = vb->planes[plane_no].length;
		vb->planes[plane_no].bytesused = size;
	}
}

/**
 * vb2_get_plane_payload() - get bytesused for the plane plane_no
 * @vb:		pointer to &struct vb2_buffer to which the plane in
 *		question belongs to.
 * @plane_no:	plane number for which payload should be set.
 */
static inline unsigned long vb2_get_plane_payload(struct vb2_buffer *vb,
				 unsigned int plane_no)
{
	if (plane_no < vb->num_planes)
		return vb->planes[plane_no].bytesused;
	return 0;
}

/**
 * vb2_plane_size() - return plane size in bytes.
 * @vb:		pointer to &struct vb2_buffer to which the plane in
 *		question belongs to.
 * @plane_no:	plane number for which size should be returned.
 */
static inline unsigned long
vb2_plane_size(struct vb2_buffer *vb, unsigned int plane_no)
{
	if (plane_no < vb->num_planes)
		return vb->planes[plane_no].length;
	return 0;
}

/**
 * vb2_start_streaming_called() - return streaming status of driver.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 */
static inline bool vb2_start_streaming_called(struct vb2_queue *q)
{
	return q->start_streaming_called;
}

/**
 * vb2_clear_last_buffer_dequeued() - clear last buffer dequeued flag of queue.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 */
static inline void vb2_clear_last_buffer_dequeued(struct vb2_queue *q)
{
	q->last_buffer_dequeued = false;
}

/**
 * vb2_get_buffer() - get a buffer from a queue
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 * @index:	buffer index
 *
 * This function obtains a buffer from a queue, by its index.
 * Keep in mind that there is no refcounting involved in this
 * operation, so the buffer lifetime should be taken into
 * consideration.
 */
static inline struct vb2_buffer *vb2_get_buffer(struct vb2_queue *q,
						unsigned int index)
{
	if (!q->bufs)
		return NULL;

	if (index >= q->max_num_buffers)
		return NULL;

	if (test_bit(index, q->bufs_bitmap))
		return q->bufs[index];
	return NULL;
}

/*
 * The following functions are not part of the vb2 core API, but are useful
 * functions for videobuf2-*.
 */

/**
 * vb2_buffer_in_use() - return true if the buffer is in use and
 * the queue cannot be freed (by the means of VIDIOC_REQBUFS(0)) call.
 *
 * @vb:		buffer for which plane size should be returned.
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 */
bool vb2_buffer_in_use(struct vb2_queue *q, struct vb2_buffer *vb);

/**
 * vb2_verify_memory_type() - Check whether the memory type and buffer type
 * passed to a buffer operation are compatible with the queue.
 *
 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 * @memory:	memory model, as defined by enum &vb2_memory.
 * @type:	private buffer type whose content is defined by the vb2-core
 *		caller. For example, for V4L2, it should match
 *		the types defined on enum &v4l2_buf_type.
 */
int vb2_verify_memory_type(struct vb2_queue *q,
		enum vb2_memory memory, unsigned int type);

/**
 * vb2_request_object_is_buffer() - return true if the object is a buffer
 *
 * @obj:	the request object.
 */
bool vb2_request_object_is_buffer(struct media_request_object *obj);

/**
 * vb2_request_buffer_cnt() - return the number of buffers in the request
 *
 * @req:	the request.
 */
unsigned int vb2_request_buffer_cnt(struct media_request *req);

#endif /* _MEDIA_VIDEOBUF2_CORE_H */