aboutsummaryrefslogtreecommitdiff
path: root/samples/v4l/v4l2-pci-skeleton.c
blob: 93b76c3220fddc888397c0005507eeafdd1fb6a3 (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
/*
 * This is a V4L2 PCI Skeleton Driver. It gives an initial skeleton source
 * for use with other PCI drivers.
 *
 * This skeleton PCI driver assumes that the card has an S-Video connector as
 * input 0 and an HDMI connector as input 1.
 *
 * Copyright 2014 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
 *
 * This program is free software; you may redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kmod.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/interrupt.h>
#include <linux/videodev2.h>
#include <linux/v4l2-dv-timings.h>
#include <media/v4l2-device.h>
#include <media/v4l2-dev.h>
#include <media/v4l2-ioctl.h>
#include <media/v4l2-dv-timings.h>
#include <media/v4l2-ctrls.h>
#include <media/v4l2-event.h>
#include <media/videobuf2-v4l2.h>
#include <media/videobuf2-dma-contig.h>

MODULE_DESCRIPTION("V4L2 PCI Skeleton Driver");
MODULE_AUTHOR("Hans Verkuil");
MODULE_LICENSE("GPL v2");

/**
 * struct skeleton - All internal data for one instance of device
 * @pdev: PCI device
 * @v4l2_dev: top-level v4l2 device struct
 * @vdev: video node structure
 * @ctrl_handler: control handler structure
 * @lock: ioctl serialization mutex
 * @std: current SDTV standard
 * @timings: current HDTV timings
 * @format: current pix format
 * @input: current video input (0 = SDTV, 1 = HDTV)
 * @queue: vb2 video capture queue
 * @qlock: spinlock controlling access to buf_list and sequence
 * @buf_list: list of buffers queued for DMA
 * @sequence: frame sequence counter
 */
struct skeleton {
	struct pci_dev *pdev;
	struct v4l2_device v4l2_dev;
	struct video_device vdev;
	struct v4l2_ctrl_handler ctrl_handler;
	struct mutex lock;
	v4l2_std_id std;
	struct v4l2_dv_timings timings;
	struct v4l2_pix_format format;
	unsigned input;

	struct vb2_queue queue;

	spinlock_t qlock;
	struct list_head buf_list;
	unsigned field;
	unsigned sequence;
};

struct skel_buffer {
	struct vb2_buffer vb;
	struct list_head list;
};

static inline struct skel_buffer *to_skel_buffer(struct vb2_buffer *vb2)
{
	return container_of(vb2, struct skel_buffer, vb);
}

static const struct pci_device_id skeleton_pci_tbl[] = {
	/* { PCI_DEVICE(PCI_VENDOR_ID_, PCI_DEVICE_ID_) }, */
	{ 0, }
};
MODULE_DEVICE_TABLE(pci, skeleton_pci_tbl);

/*
 * HDTV: this structure has the capabilities of the HDTV receiver.
 * It is used to constrain the huge list of possible formats based
 * upon the hardware capabilities.
 */
static const struct v4l2_dv_timings_cap skel_timings_cap = {
	.type = V4L2_DV_BT_656_1120,
	/* keep this initialization for compatibility with GCC < 4.4.6 */
	.reserved = { 0 },
	V4L2_INIT_BT_TIMINGS(
		720, 1920,		/* min/max width */
		480, 1080,		/* min/max height */
		27000000, 74250000,	/* min/max pixelclock*/
		V4L2_DV_BT_STD_CEA861,	/* Supported standards */
		/* capabilities */
		V4L2_DV_BT_CAP_INTERLACED | V4L2_DV_BT_CAP_PROGRESSIVE
	)
};

/*
 * Supported SDTV standards. This does the same job as skel_timings_cap, but
 * for standard TV formats.
 */
#define SKEL_TVNORMS V4L2_STD_ALL

/*
 * Interrupt handler: typically interrupts happen after a new frame has been
 * captured. It is the job of the handler to remove the new frame from the
 * internal list and give it back to the vb2 framework, updating the sequence
 * counter, field and timestamp at the same time.
 */
static irqreturn_t skeleton_irq(int irq, void *dev_id)
{
#ifdef TODO
	struct skeleton *skel = dev_id;

	/* handle interrupt */

	/* Once a new frame has been captured, mark it as done like this: */
	if (captured_new_frame) {
		...
		spin_lock(&skel->qlock);
		list_del(&new_buf->list);
		spin_unlock(&skel->qlock);
		v4l2_get_timestamp(&new_buf->vb.v4l2_buf.timestamp);
		new_buf->vb.v4l2_buf.sequence = skel->sequence++;
		new_buf->vb.v4l2_buf.field = skel->field;
		if (skel->format.field == V4L2_FIELD_ALTERNATE) {
			if (skel->field == V4L2_FIELD_BOTTOM)
				skel->field = V4L2_FIELD_TOP;
			else if (skel->field == V4L2_FIELD_TOP)
				skel->field = V4L2_FIELD_BOTTOM;
		}
		vb2_buffer_done(&new_buf->vb, VB2_BUF_STATE_DONE);
	}
#endif
	return IRQ_HANDLED;
}

/*
 * Setup the constraints of the queue: besides setting the number of planes
 * per buffer and the size and allocation context of each plane, it also
 * checks if sufficient buffers have been allocated. Usually 3 is a good
 * minimum number: many DMA engines need a minimum of 2 buffers in the
 * queue and you need to have another available for userspace processing.
 */
static int queue_setup(struct vb2_queue *vq,
		       unsigned int *nbuffers, unsigned int *nplanes,
		       unsigned int sizes[], struct device *alloc_devs[])
{
	struct skeleton *skel = vb2_get_drv_priv(vq);

	skel->field = skel->format.field;
	if (skel->field == V4L2_FIELD_ALTERNATE) {
		/*
		 * You cannot use read() with FIELD_ALTERNATE since the field
		 * information (TOP/BOTTOM) cannot be passed back to the user.
		 */
		if (vb2_fileio_is_active(vq))
			return -EINVAL;
		skel->field = V4L2_FIELD_TOP;
	}

	if (vq->num_buffers + *nbuffers < 3)
		*nbuffers = 3 - vq->num_buffers;

	if (*nplanes)
		return sizes[0] < skel->format.sizeimage ? -EINVAL : 0;
	*nplanes = 1;
	sizes[0] = skel->format.sizeimage;
	return 0;
}

/*
 * Prepare the buffer for queueing to the DMA engine: check and set the
 * payload size.
 */
static int buffer_prepare(struct vb2_buffer *vb)
{
	struct skeleton *skel = vb2_get_drv_priv(vb->vb2_queue);
	unsigned long size = skel->format.sizeimage;

	if (vb2_plane_size(vb, 0) < size) {
		dev_err(&skel->pdev->dev, "buffer too small (%lu < %lu)\n",
			 vb2_plane_size(vb, 0), size);
		return -EINVAL;
	}

	vb2_set_plane_payload(vb, 0, size);
	return 0;
}

/*
 * Queue this buffer to the DMA engine.
 */
static void buffer_queue(struct vb2_buffer *vb)
{
	struct skeleton *skel = vb2_get_drv_priv(vb->vb2_queue);
	struct skel_buffer *buf = to_skel_buffer(vb);
	unsigned long flags;

	spin_lock_irqsave(&skel->qlock, flags);
	list_add_tail(&buf->list, &skel->buf_list);

	/* TODO: Update any DMA pointers if necessary */

	spin_unlock_irqrestore(&skel->qlock, flags);
}

static void return_all_buffers(struct skeleton *skel,
			       enum vb2_buffer_state state)
{
	struct skel_buffer *buf, *node;
	unsigned long flags;

	spin_lock_irqsave(&skel->qlock, flags);
	list_for_each_entry_safe(buf, node, &skel->buf_list, list) {
		vb2_buffer_done(&buf->vb, state);
		list_del(&buf->list);
	}
	spin_unlock_irqrestore(&skel->qlock, flags);
}

/*
 * Start streaming. First check if the minimum number of buffers have been
 * queued. If not, then return -ENOBUFS and the vb2 framework will call
 * this function again the next time a buffer has been queued until enough
 * buffers are available to actually start the DMA engine.
 */
static int start_streaming(struct vb2_queue *vq, unsigned int count)
{
	struct skeleton *skel = vb2_get_drv_priv(vq);
	int ret = 0;

	skel->sequence = 0;

	/* TODO: start DMA */

	if (ret) {
		/*
		 * In case of an error, return all active buffers to the
		 * QUEUED state
		 */
		return_all_buffers(skel, VB2_BUF_STATE_QUEUED);
	}
	return ret;
}

/*
 * Stop the DMA engine. Any remaining buffers in the DMA queue are dequeued
 * and passed on to the vb2 framework marked as STATE_ERROR.
 */
static void stop_streaming(struct vb2_queue *vq)
{
	struct skeleton *skel = vb2_get_drv_priv(vq);

	/* TODO: stop DMA */

	/* Release all active buffers */
	return_all_buffers(skel, VB2_BUF_STATE_ERROR);
}

/*
 * The vb2 queue ops. Note that since q->lock is set we can use the standard
 * vb2_ops_wait_prepare/finish helper functions. If q->lock would be NULL,
 * then this driver would have to provide these ops.
 */
static struct vb2_ops skel_qops = {
	.queue_setup		= queue_setup,
	.buf_prepare		= buffer_prepare,
	.buf_queue		= buffer_queue,
	.start_streaming	= start_streaming,
	.stop_streaming		= stop_streaming,
	.wait_prepare		= vb2_ops_wait_prepare,
	.wait_finish		= vb2_ops_wait_finish,
};

/*
 * Required ioctl querycap. Note that the version field is prefilled with
 * the version of the kernel.
 */
static int skeleton_querycap(struct file *file, void *priv,
			     struct v4l2_capability *cap)
{
	struct skeleton *skel = video_drvdata(file);

	strlcpy(cap->driver, KBUILD_MODNAME, sizeof(cap->driver));
	strlcpy(cap->card, "V4L2 PCI Skeleton", sizeof(cap->card));
	snprintf(cap->bus_info, sizeof(cap->bus_info), "PCI:%s",
		 pci_name(skel->pdev));
	return 0;
}

/*
 * Helper function to check and correct struct v4l2_pix_format. It's used
 * not only in VIDIOC_TRY/S_FMT, but also elsewhere if changes to the SDTV
 * standard, HDTV timings or the video input would require updating the
 * current format.
 */
static void skeleton_fill_pix_format(struct skeleton *skel,
				     struct v4l2_pix_format *pix)
{
	pix->pixelformat = V4L2_PIX_FMT_YUYV;
	if (skel->input == 0) {
		/* S-Video input */
		pix->width = 720;
		pix->height = (skel->std & V4L2_STD_525_60) ? 480 : 576;
		pix->field = V4L2_FIELD_INTERLACED;
		pix->colorspace = V4L2_COLORSPACE_SMPTE170M;
	} else {
		/* HDMI input */
		pix->width = skel->timings.bt.width;
		pix->height = skel->timings.bt.height;
		if (skel->timings.bt.interlaced) {
			pix->field = V4L2_FIELD_ALTERNATE;
			pix->height /= 2;
		} else {
			pix->field = V4L2_FIELD_NONE;
		}
		pix->colorspace = V4L2_COLORSPACE_REC709;
	}

	/*
	 * The YUYV format is four bytes for every two pixels, so bytesperline
	 * is width * 2.
	 */
	pix->bytesperline = pix->width * 2;
	pix->sizeimage = pix->bytesperline * pix->height;
	pix->priv = 0;
}

static int skeleton_try_fmt_vid_cap(struct file *file, void *priv,
				    struct v4l2_format *f)
{
	struct skeleton *skel = video_drvdata(file);
	struct v4l2_pix_format *pix = &f->fmt.pix;

	/*
	 * Due to historical reasons providing try_fmt with an unsupported
	 * pixelformat will return -EINVAL for video receivers. Webcam drivers,
	 * however, will silently correct the pixelformat. Some video capture
	 * applications rely on this behavior...
	 */
	if (pix->pixelformat != V4L2_PIX_FMT_YUYV)
		return -EINVAL;
	skeleton_fill_pix_format(skel, pix);
	return 0;
}

static int skeleton_s_fmt_vid_cap(struct file *file, void *priv,
				  struct v4l2_format *f)
{
	struct skeleton *skel = video_drvdata(file);
	int ret;

	ret = skeleton_try_fmt_vid_cap(file, priv, f);
	if (ret)
		return ret;

	/*
	 * It is not allowed to change the format while buffers for use with
	 * streaming have already been allocated.
	 */
	if (vb2_is_busy(&skel->queue))
		return -EBUSY;

	/* TODO: change format */
	skel->format = f->fmt.pix;
	return 0;
}

static int skeleton_g_fmt_vid_cap(struct file *file, void *priv,
				  struct v4l2_format *f)
{
	struct skeleton *skel = video_drvdata(file);

	f->fmt.pix = skel->format;
	return 0;
}

static int skeleton_enum_fmt_vid_cap(struct file *file, void *priv,
				     struct v4l2_fmtdesc *f)
{
	if (f->index != 0)
		return -EINVAL;

	f->pixelformat = V4L2_PIX_FMT_YUYV;
	return 0;
}

static int skeleton_s_std(struct file *file, void *priv, v4l2_std_id std)
{
	struct skeleton *skel = video_drvdata(file);

	/* S_STD is not supported on the HDMI input */
	if (skel->input)
		return -ENODATA;

	/*
	 * No change, so just return. Some applications call S_STD again after
	 * the buffers for streaming have been set up, so we have to allow for
	 * this behavior.
	 */
	if (std == skel->std)
		return 0;

	/*
	 * Changing the standard implies a format change, which is not allowed
	 * while buffers for use with streaming have already been allocated.
	 */
	if (vb2_is_busy(&skel->queue))
		return -EBUSY;

	/* TODO: handle changing std */

	skel->std = std;

	/* Update the internal format */
	skeleton_fill_pix_format(skel, &skel->format);
	return 0;
}

static int skeleton_g_std(struct file *file, void *priv, v4l2_std_id *std)
{
	struct skeleton *skel = video_drvdata(file);

	/* G_STD is not supported on the HDMI input */
	if (skel->input)
		return -ENODATA;

	*std = skel->std;
	return 0;
}

/*
 * Query the current standard as seen by the hardware. This function shall
 * never actually change the standard, it just detects and reports.
 * The framework will initially set *std to tvnorms (i.e. the set of
 * supported standards by this input), and this function should just AND
 * this value. If there is no signal, then *std should be set to 0.
 */
static int skeleton_querystd(struct file *file, void *priv, v4l2_std_id *std)
{
	struct skeleton *skel = video_drvdata(file);

	/* QUERY_STD is not supported on the HDMI input */
	if (skel->input)
		return -ENODATA;

#ifdef TODO
	/*
	 * Query currently seen standard. Initial value of *std is
	 * V4L2_STD_ALL. This function should look something like this:
	 */
	get_signal_info();
	if (no_signal) {
		*std = 0;
		return 0;
	}
	/* Use signal information to reduce the number of possible standards */
	if (signal_has_525_lines)
		*std &= V4L2_STD_525_60;
	else
		*std &= V4L2_STD_625_50;
#endif
	return 0;
}

static int skeleton_s_dv_timings(struct file *file, void *_fh,
				 struct v4l2_dv_timings *timings)
{
	struct skeleton *skel = video_drvdata(file);

	/* S_DV_TIMINGS is not supported on the S-Video input */
	if (skel->input == 0)
		return -ENODATA;

	/* Quick sanity check */
	if (!v4l2_valid_dv_timings(timings, &skel_timings_cap, NULL, NULL))
		return -EINVAL;

	/* Check if the timings are part of the CEA-861 timings. */
	if (!v4l2_find_dv_timings_cap(timings, &skel_timings_cap,
				      0, NULL, NULL))
		return -EINVAL;

	/* Return 0 if the new timings are the same as the current timings. */
	if (v4l2_match_dv_timings(timings, &skel->timings, 0, false))
		return 0;

	/*
	 * Changing the timings implies a format change, which is not allowed
	 * while buffers for use with streaming have already been allocated.
	 */
	if (vb2_is_busy(&skel->queue))
		return -EBUSY;

	/* TODO: Configure new timings */

	/* Save timings */
	skel->timings = *timings;

	/* Update the internal format */
	skeleton_fill_pix_format(skel, &skel->format);
	return 0;
}

static int skeleton_g_dv_timings(struct file *file, void *_fh,
				 struct v4l2_dv_timings *timings)
{
	struct skeleton *skel = video_drvdata(file);

	/* G_DV_TIMINGS is not supported on the S-Video input */
	if (skel->input == 0)
		return -ENODATA;

	*timings = skel->timings;
	return 0;
}

static int skeleton_enum_dv_timings(struct file *file, void *_fh,
				    struct v4l2_enum_dv_timings *timings)
{
	struct skeleton *skel = video_drvdata(file);

	/* ENUM_DV_TIMINGS is not supported on the S-Video input */
	if (skel->input == 0)
		return -ENODATA;

	return v4l2_enum_dv_timings_cap(timings, &skel_timings_cap,
					NULL, NULL);
}

/*
 * Query the current timings as seen by the hardware. This function shall
 * never actually change the timings, it just detects and reports.
 * If no signal is detected, then return -ENOLINK. If the hardware cannot
 * lock to the signal, then return -ENOLCK. If the signal is out of range
 * of the capabilities of the system (e.g., it is possible that the receiver
 * can lock but that the DMA engine it is connected to cannot handle
 * pixelclocks above a certain frequency), then -ERANGE is returned.
 */
static int skeleton_query_dv_timings(struct file *file, void *_fh,
				     struct v4l2_dv_timings *timings)
{
	struct skeleton *skel = video_drvdata(file);

	/* QUERY_DV_TIMINGS is not supported on the S-Video input */
	if (skel->input == 0)
		return -ENODATA;

#ifdef TODO
	/*
	 * Query currently seen timings. This function should look
	 * something like this:
	 */
	detect_timings();
	if (no_signal)
		return -ENOLINK;
	if (cannot_lock_to_signal)
		return -ENOLCK;
	if (signal_out_of_range_of_capabilities)
		return -ERANGE;

	/* Useful for debugging */
	v4l2_print_dv_timings(skel->v4l2_dev.name, "query_dv_timings:",
			timings, true);
#endif
	return 0;
}

static int skeleton_dv_timings_cap(struct file *file, void *fh,
				   struct v4l2_dv_timings_cap *cap)
{
	struct skeleton *skel = video_drvdata(file);

	/* DV_TIMINGS_CAP is not supported on the S-Video input */
	if (skel->input == 0)
		return -ENODATA;
	*cap = skel_timings_cap;
	return 0;
}

static int skeleton_enum_input(struct file *file, void *priv,
			       struct v4l2_input *i)
{
	if (i->index > 1)
		return -EINVAL;

	i->type = V4L2_INPUT_TYPE_CAMERA;
	if (i->index == 0) {
		i->std = SKEL_TVNORMS;
		strlcpy(i->name, "S-Video", sizeof(i->name));
		i->capabilities = V4L2_IN_CAP_STD;
	} else {
		i->std = 0;
		strlcpy(i->name, "HDMI", sizeof(i->name));
		i->capabilities = V4L2_IN_CAP_DV_TIMINGS;
	}
	return 0;
}

static int skeleton_s_input(struct file *file, void *priv, unsigned int i)
{
	struct skeleton *skel = video_drvdata(file);

	if (i > 1)
		return -EINVAL;

	/*
	 * Changing the input implies a format change, which is not allowed
	 * while buffers for use with streaming have already been allocated.
	 */
	if (vb2_is_busy(&skel->queue))
		return -EBUSY;

	skel->input = i;
	/*
	 * Update tvnorms. The tvnorms value is used by the core to implement
	 * VIDIOC_ENUMSTD so it has to be correct. If tvnorms == 0, then
	 * ENUMSTD will return -ENODATA.
	 */
	skel->vdev.tvnorms = i ? 0 : SKEL_TVNORMS;

	/* Update the internal format */
	skeleton_fill_pix_format(skel, &skel->format);
	return 0;
}

static int skeleton_g_input(struct file *file, void *priv, unsigned int *i)
{
	struct skeleton *skel = video_drvdata(file);

	*i = skel->input;
	return 0;
}

/* The control handler. */
static int skeleton_s_ctrl(struct v4l2_ctrl *ctrl)
{
	/*struct skeleton *skel =
		container_of(ctrl->handler, struct skeleton, ctrl_handler);*/

	switch (ctrl->id) {
	case V4L2_CID_BRIGHTNESS:
		/* TODO: set brightness to ctrl->val */
		break;
	case V4L2_CID_CONTRAST:
		/* TODO: set contrast to ctrl->val */
		break;
	case V4L2_CID_SATURATION:
		/* TODO: set saturation to ctrl->val */
		break;
	case V4L2_CID_HUE:
		/* TODO: set hue to ctrl->val */
		break;
	default:
		return -EINVAL;
	}
	return 0;
}

/* ------------------------------------------------------------------
	File operations for the device
   ------------------------------------------------------------------*/

static const struct v4l2_ctrl_ops skel_ctrl_ops = {
	.s_ctrl = skeleton_s_ctrl,
};

/*
 * The set of all supported ioctls. Note that all the streaming ioctls
 * use the vb2 helper functions that take care of all the locking and
 * that also do ownership tracking (i.e. only the filehandle that requested
 * the buffers can call the streaming ioctls, all other filehandles will
 * receive -EBUSY if they attempt to call the same streaming ioctls).
 *
 * The last three ioctls also use standard helper functions: these implement
 * standard behavior for drivers with controls.
 */
static const struct v4l2_ioctl_ops skel_ioctl_ops = {
	.vidioc_querycap = skeleton_querycap,
	.vidioc_try_fmt_vid_cap = skeleton_try_fmt_vid_cap,
	.vidioc_s_fmt_vid_cap = skeleton_s_fmt_vid_cap,
	.vidioc_g_fmt_vid_cap = skeleton_g_fmt_vid_cap,
	.vidioc_enum_fmt_vid_cap = skeleton_enum_fmt_vid_cap,

	.vidioc_g_std = skeleton_g_std,
	.vidioc_s_std = skeleton_s_std,
	.vidioc_querystd = skeleton_querystd,

	.vidioc_s_dv_timings = skeleton_s_dv_timings,
	.vidioc_g_dv_timings = skeleton_g_dv_timings,
	.vidioc_enum_dv_timings = skeleton_enum_dv_timings,
	.vidioc_query_dv_timings = skeleton_query_dv_timings,
	.vidioc_dv_timings_cap = skeleton_dv_timings_cap,

	.vidioc_enum_input = skeleton_enum_input,
	.vidioc_g_input = skeleton_g_input,
	.vidioc_s_input = skeleton_s_input,

	.vidioc_reqbufs = vb2_ioctl_reqbufs,
	.vidioc_create_bufs = vb2_ioctl_create_bufs,
	.vidioc_querybuf = vb2_ioctl_querybuf,
	.vidioc_qbuf = vb2_ioctl_qbuf,
	.vidioc_dqbuf = vb2_ioctl_dqbuf,
	.vidioc_expbuf = vb2_ioctl_expbuf,
	.vidioc_streamon = vb2_ioctl_streamon,
	.vidioc_streamoff = vb2_ioctl_streamoff,

	.vidioc_log_status = v4l2_ctrl_log_status,
	.vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
	.vidioc_unsubscribe_event = v4l2_event_unsubscribe,
};

/*
 * The set of file operations. Note that all these ops are standard core
 * helper functions.
 */
static const struct v4l2_file_operations skel_fops = {
	.owner = THIS_MODULE,
	.open = v4l2_fh_open,
	.release = vb2_fop_release,
	.unlocked_ioctl = video_ioctl2,
	.read = vb2_fop_read,
	.mmap = vb2_fop_mmap,
	.poll = vb2_fop_poll,
};

/*
 * The initial setup of this device instance. Note that the initial state of
 * the driver should be complete. So the initial format, standard, timings
 * and video input should all be initialized to some reasonable value.
 */
static int skeleton_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
{
	/* The initial timings are chosen to be 720p60. */
	static const struct v4l2_dv_timings timings_def =
		V4L2_DV_BT_CEA_1280X720P60;
	struct skeleton *skel;
	struct video_device *vdev;
	struct v4l2_ctrl_handler *hdl;
	struct vb2_queue *q;
	int ret;

	/* Enable PCI */
	ret = pci_enable_device(pdev);
	if (ret)
		return ret;
	ret = pci_set_dma_mask(pdev, DMA_BIT_MASK(32));
	if (ret) {
		dev_err(&pdev->dev, "no suitable DMA available.\n");
		goto disable_pci;
	}

	/* Allocate a new instance */
	skel = devm_kzalloc(&pdev->dev, sizeof(struct skeleton), GFP_KERNEL);
	if (!skel)
		return -ENOMEM;

	/* Allocate the interrupt */
	ret = devm_request_irq(&pdev->dev, pdev->irq,
			       skeleton_irq, 0, KBUILD_MODNAME, skel);
	if (ret) {
		dev_err(&pdev->dev, "request_irq failed\n");
		goto disable_pci;
	}
	skel->pdev = pdev;

	/* Fill in the initial format-related settings */
	skel->timings = timings_def;
	skel->std = V4L2_STD_625_50;
	skeleton_fill_pix_format(skel, &skel->format);

	/* Initialize the top-level structure */
	ret = v4l2_device_register(&pdev->dev, &skel->v4l2_dev);
	if (ret)
		goto disable_pci;

	mutex_init(&skel->lock);

	/* Add the controls */
	hdl = &skel->ctrl_handler;
	v4l2_ctrl_handler_init(hdl, 4);
	v4l2_ctrl_new_std(hdl, &skel_ctrl_ops,
			  V4L2_CID_BRIGHTNESS, 0, 255, 1, 127);
	v4l2_ctrl_new_std(hdl, &skel_ctrl_ops,
			  V4L2_CID_CONTRAST, 0, 255, 1, 16);
	v4l2_ctrl_new_std(hdl, &skel_ctrl_ops,
			  V4L2_CID_SATURATION, 0, 255, 1, 127);
	v4l2_ctrl_new_std(hdl, &skel_ctrl_ops,
			  V4L2_CID_HUE, -128, 127, 1, 0);
	if (hdl->error) {
		ret = hdl->error;
		goto free_hdl;
	}
	skel->v4l2_dev.ctrl_handler = hdl;

	/* Initialize the vb2 queue */
	q = &skel->queue;
	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	q->io_modes = VB2_MMAP | VB2_DMABUF | VB2_READ;
	q->dev = &pdev->dev;
	q->drv_priv = skel;
	q->buf_struct_size = sizeof(struct skel_buffer);
	q->ops = &skel_qops;
	q->mem_ops = &vb2_dma_contig_memops;
	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
	/*
	 * Assume that this DMA engine needs to have at least two buffers
	 * available before it can be started. The start_streaming() op
	 * won't be called until at least this many buffers are queued up.
	 */
	q->min_buffers_needed = 2;
	/*
	 * The serialization lock for the streaming ioctls. This is the same
	 * as the main serialization lock, but if some of the non-streaming
	 * ioctls could take a long time to execute, then you might want to
	 * have a different lock here to prevent VIDIOC_DQBUF from being
	 * blocked while waiting for another action to finish. This is
	 * generally not needed for PCI devices, but USB devices usually do
	 * want a separate lock here.
	 */
	q->lock = &skel->lock;
	/*
	 * Since this driver can only do 32-bit DMA we must make sure that
	 * the vb2 core will allocate the buffers in 32-bit DMA memory.
	 */
	q->gfp_flags = GFP_DMA32;
	ret = vb2_queue_init(q);
	if (ret)
		goto free_hdl;

	INIT_LIST_HEAD(&skel->buf_list);
	spin_lock_init(&skel->qlock);

	/* Initialize the video_device structure */
	vdev = &skel->vdev;
	strlcpy(vdev->name, KBUILD_MODNAME, sizeof(vdev->name));
	/*
	 * There is nothing to clean up, so release is set to an empty release
	 * function. The release callback must be non-NULL.
	 */
	vdev->release = video_device_release_empty;
	vdev->fops = &skel_fops,
	vdev->ioctl_ops = &skel_ioctl_ops,
	vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_READWRITE |
			    V4L2_CAP_STREAMING;
	/*
	 * The main serialization lock. All ioctls are serialized by this
	 * lock. Exception: if q->lock is set, then the streaming ioctls
	 * are serialized by that separate lock.
	 */
	vdev->lock = &skel->lock;
	vdev->queue = q;
	vdev->v4l2_dev = &skel->v4l2_dev;
	/* Supported SDTV standards, if any */
	vdev->tvnorms = SKEL_TVNORMS;
	video_set_drvdata(vdev, skel);

	ret = video_register_device(vdev, VFL_TYPE_GRABBER, -1);
	if (ret)
		goto free_hdl;

	dev_info(&pdev->dev, "V4L2 PCI Skeleton Driver loaded\n");
	return 0;

free_hdl:
	v4l2_ctrl_handler_free(&skel->ctrl_handler);
	v4l2_device_unregister(&skel->v4l2_dev);
disable_pci:
	pci_disable_device(pdev);
	return ret;
}

static void skeleton_remove(struct pci_dev *pdev)
{
	struct v4l2_device *v4l2_dev = pci_get_drvdata(pdev);
	struct skeleton *skel = container_of(v4l2_dev, struct skeleton, v4l2_dev);

	video_unregister_device(&skel->vdev);
	v4l2_ctrl_handler_free(&skel->ctrl_handler);
	v4l2_device_unregister(&skel->v4l2_dev);
	pci_disable_device(skel->pdev);
}

static struct pci_driver skeleton_driver = {
	.name = KBUILD_MODNAME,
	.probe = skeleton_probe,
	.remove = skeleton_remove,
	.id_table = skeleton_pci_tbl,
};

module_pci_driver(skeleton_driver);