summaryrefslogtreecommitdiffstats
path: root/kernel/drivers/input/touchscreen/sur40.c
blob: a24eba5ea843e632af7e07962e520d2271f7ae6b (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
/*
 * Surface2.0/SUR40/PixelSense input driver
 *
 * Copyright (c) 2014 by Florian 'floe' Echtler <floe@butterbrot.org>
 *
 * Derived from the USB Skeleton driver 1.1,
 * Copyright (c) 2003 Greg Kroah-Hartman (greg@kroah.com)
 *
 * and from the Apple USB BCM5974 multitouch driver,
 * Copyright (c) 2008 Henrik Rydberg (rydberg@euromail.se)
 *
 * and from the generic hid-multitouch driver,
 * Copyright (c) 2010-2012 Stephane Chatty <chatty@enac.fr>
 *
 * and from the v4l2-pci-skeleton driver,
 * Copyright (c) Copyright 2014 Cisco Systems, Inc.
 *
 * 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; either version 2 of
 * the License, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/completion.h>
#include <linux/uaccess.h>
#include <linux/usb.h>
#include <linux/printk.h>
#include <linux/input-polldev.h>
#include <linux/input/mt.h>
#include <linux/usb/input.h>
#include <linux/videodev2.h>
#include <media/v4l2-device.h>
#include <media/v4l2-dev.h>
#include <media/v4l2-ioctl.h>
#include <media/videobuf2-dma-sg.h>

/* read 512 bytes from endpoint 0x86 -> get header + blobs */
struct sur40_header {

	__le16 type;       /* always 0x0001 */
	__le16 count;      /* count of blobs (if 0: continue prev. packet) */

	__le32 packet_id;  /* unique ID for all packets in one frame */

	__le32 timestamp;  /* milliseconds (inc. by 16 or 17 each frame) */
	__le32 unknown;    /* "epoch?" always 02/03 00 00 00 */

} __packed;

struct sur40_blob {

	__le16 blob_id;

	u8 action;         /* 0x02 = enter/exit, 0x03 = update (?) */
	u8 unknown;        /* always 0x01 or 0x02 (no idea what this is?) */

	__le16 bb_pos_x;   /* upper left corner of bounding box */
	__le16 bb_pos_y;

	__le16 bb_size_x;  /* size of bounding box */
	__le16 bb_size_y;

	__le16 pos_x;      /* finger tip position */
	__le16 pos_y;

	__le16 ctr_x;      /* centroid position */
	__le16 ctr_y;

	__le16 axis_x;     /* somehow related to major/minor axis, mostly: */
	__le16 axis_y;     /* axis_x == bb_size_y && axis_y == bb_size_x */

	__le32 angle;      /* orientation in radians relative to x axis -
	                      actually an IEEE754 float, don't use in kernel */

	__le32 area;       /* size in pixels/pressure (?) */

	u8 padding[32];

} __packed;

/* combined header/blob data */
struct sur40_data {
	struct sur40_header header;
	struct sur40_blob   blobs[];
} __packed;

/* read 512 bytes from endpoint 0x82 -> get header below
 * continue reading 16k blocks until header.size bytes read */
struct sur40_image_header {
	__le32 magic;     /* "SUBF" */
	__le32 packet_id;
	__le32 size;      /* always 0x0007e900 = 960x540 */
	__le32 timestamp; /* milliseconds (increases by 16 or 17 each frame) */
	__le32 unknown;   /* "epoch?" always 02/03 00 00 00 */
} __packed;

/* version information */
#define DRIVER_SHORT   "sur40"
#define DRIVER_LONG    "Samsung SUR40"
#define DRIVER_AUTHOR  "Florian 'floe' Echtler <floe@butterbrot.org>"
#define DRIVER_DESC    "Surface2.0/SUR40/PixelSense input driver"

/* vendor and device IDs */
#define ID_MICROSOFT 0x045e
#define ID_SUR40     0x0775

/* sensor resolution */
#define SENSOR_RES_X 1920
#define SENSOR_RES_Y 1080

/* touch data endpoint */
#define TOUCH_ENDPOINT 0x86

/* video data endpoint */
#define VIDEO_ENDPOINT 0x82

/* video header fields */
#define VIDEO_HEADER_MAGIC 0x46425553
#define VIDEO_PACKET_SIZE  16384

/* polling interval (ms) */
#define POLL_INTERVAL 10

/* maximum number of contacts FIXME: this is a guess? */
#define MAX_CONTACTS 64

/* control commands */
#define SUR40_GET_VERSION 0xb0 /* 12 bytes string    */
#define SUR40_UNKNOWN1    0xb3 /*  5 bytes           */
#define SUR40_UNKNOWN2    0xc1 /* 24 bytes           */

#define SUR40_GET_STATE   0xc5 /*  4 bytes state (?) */
#define SUR40_GET_SENSORS 0xb1 /*  8 bytes sensors   */

/* master device state */
struct sur40_state {

	struct usb_device *usbdev;
	struct device *dev;
	struct input_polled_dev *input;

	struct v4l2_device v4l2;
	struct video_device vdev;
	struct mutex lock;

	struct vb2_queue queue;
	struct vb2_alloc_ctx *alloc_ctx;
	struct list_head buf_list;
	spinlock_t qlock;
	int sequence;

	struct sur40_data *bulk_in_buffer;
	size_t bulk_in_size;
	u8 bulk_in_epaddr;

	char phys[64];
};

struct sur40_buffer {
	struct vb2_buffer vb;
	struct list_head list;
};

/* forward declarations */
static const struct video_device sur40_video_device;
static const struct v4l2_pix_format sur40_video_format;
static const struct vb2_queue sur40_queue;
static void sur40_process_video(struct sur40_state *sur40);

/*
 * Note: an earlier, non-public version of this driver used USB_RECIP_ENDPOINT
 * here by mistake which is very likely to have corrupted the firmware EEPROM
 * on two separate SUR40 devices. Thanks to Alan Stern who spotted this bug.
 * Should you ever run into a similar problem, the background story to this
 * incident and instructions on how to fix the corrupted EEPROM are available
 * at https://floe.butterbrot.org/matrix/hacking/surface/brick.html
*/

/* command wrapper */
static int sur40_command(struct sur40_state *dev,
			 u8 command, u16 index, void *buffer, u16 size)
{
	return usb_control_msg(dev->usbdev, usb_rcvctrlpipe(dev->usbdev, 0),
			       command,
			       USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
			       0x00, index, buffer, size, 1000);
}

/* Initialization routine, called from sur40_open */
static int sur40_init(struct sur40_state *dev)
{
	int result;
	u8 buffer[24];

	/* stupidly replay the original MS driver init sequence */
	result = sur40_command(dev, SUR40_GET_VERSION, 0x00, buffer, 12);
	if (result < 0)
		return result;

	result = sur40_command(dev, SUR40_GET_VERSION, 0x01, buffer, 12);
	if (result < 0)
		return result;

	result = sur40_command(dev, SUR40_GET_VERSION, 0x02, buffer, 12);
	if (result < 0)
		return result;

	result = sur40_command(dev, SUR40_UNKNOWN2,    0x00, buffer, 24);
	if (result < 0)
		return result;

	result = sur40_command(dev, SUR40_UNKNOWN1,    0x00, buffer,  5);
	if (result < 0)
		return result;

	result = sur40_command(dev, SUR40_GET_VERSION, 0x03, buffer, 12);

	/*
	 * Discard the result buffer - no known data inside except
	 * some version strings, maybe extract these sometime...
	 */

	return result;
}

/*
 * Callback routines from input_polled_dev
 */

/* Enable the device, polling will now start. */
static void sur40_open(struct input_polled_dev *polldev)
{
	struct sur40_state *sur40 = polldev->private;

	dev_dbg(sur40->dev, "open\n");
	sur40_init(sur40);
}

/* Disable device, polling has stopped. */
static void sur40_close(struct input_polled_dev *polldev)
{
	struct sur40_state *sur40 = polldev->private;

	dev_dbg(sur40->dev, "close\n");
	/*
	 * There is no known way to stop the device, so we simply
	 * stop polling.
	 */
}

/*
 * This function is called when a whole contact has been processed,
 * so that it can assign it to a slot and store the data there.
 */
static void sur40_report_blob(struct sur40_blob *blob, struct input_dev *input)
{
	int wide, major, minor;

	int bb_size_x = le16_to_cpu(blob->bb_size_x);
	int bb_size_y = le16_to_cpu(blob->bb_size_y);

	int pos_x = le16_to_cpu(blob->pos_x);
	int pos_y = le16_to_cpu(blob->pos_y);

	int ctr_x = le16_to_cpu(blob->ctr_x);
	int ctr_y = le16_to_cpu(blob->ctr_y);

	int slotnum = input_mt_get_slot_by_key(input, blob->blob_id);
	if (slotnum < 0 || slotnum >= MAX_CONTACTS)
		return;

	input_mt_slot(input, slotnum);
	input_mt_report_slot_state(input, MT_TOOL_FINGER, 1);
	wide = (bb_size_x > bb_size_y);
	major = max(bb_size_x, bb_size_y);
	minor = min(bb_size_x, bb_size_y);

	input_report_abs(input, ABS_MT_POSITION_X, pos_x);
	input_report_abs(input, ABS_MT_POSITION_Y, pos_y);
	input_report_abs(input, ABS_MT_TOOL_X, ctr_x);
	input_report_abs(input, ABS_MT_TOOL_Y, ctr_y);

	/* TODO: use a better orientation measure */
	input_report_abs(input, ABS_MT_ORIENTATION, wide);
	input_report_abs(input, ABS_MT_TOUCH_MAJOR, major);
	input_report_abs(input, ABS_MT_TOUCH_MINOR, minor);
}

/* core function: poll for new input data */
static void sur40_poll(struct input_polled_dev *polldev)
{
	struct sur40_state *sur40 = polldev->private;
	struct input_dev *input = polldev->input;
	int result, bulk_read, need_blobs, packet_blobs, i;
	u32 uninitialized_var(packet_id);

	struct sur40_header *header = &sur40->bulk_in_buffer->header;
	struct sur40_blob *inblob = &sur40->bulk_in_buffer->blobs[0];

	dev_dbg(sur40->dev, "poll\n");

	need_blobs = -1;

	do {

		/* perform a blocking bulk read to get data from the device */
		result = usb_bulk_msg(sur40->usbdev,
			usb_rcvbulkpipe(sur40->usbdev, sur40->bulk_in_epaddr),
			sur40->bulk_in_buffer, sur40->bulk_in_size,
			&bulk_read, 1000);

		dev_dbg(sur40->dev, "received %d bytes\n", bulk_read);

		if (result < 0) {
			dev_err(sur40->dev, "error in usb_bulk_read\n");
			return;
		}

		result = bulk_read - sizeof(struct sur40_header);

		if (result % sizeof(struct sur40_blob) != 0) {
			dev_err(sur40->dev, "transfer size mismatch\n");
			return;
		}

		/* first packet? */
		if (need_blobs == -1) {
			need_blobs = le16_to_cpu(header->count);
			dev_dbg(sur40->dev, "need %d blobs\n", need_blobs);
			packet_id = le32_to_cpu(header->packet_id);
		}

		/*
		 * Sanity check. when video data is also being retrieved, the
		 * packet ID will usually increase in the middle of a series
		 * instead of at the end.
		 */
		if (packet_id != header->packet_id)
			dev_warn(sur40->dev, "packet ID mismatch\n");

		packet_blobs = result / sizeof(struct sur40_blob);
		dev_dbg(sur40->dev, "received %d blobs\n", packet_blobs);

		/* packets always contain at least 4 blobs, even if empty */
		if (packet_blobs > need_blobs)
			packet_blobs = need_blobs;

		for (i = 0; i < packet_blobs; i++) {
			need_blobs--;
			dev_dbg(sur40->dev, "processing blob\n");
			sur40_report_blob(&(inblob[i]), input);
		}

	} while (need_blobs > 0);

	input_mt_sync_frame(input);
	input_sync(input);

	sur40_process_video(sur40);
}

/* deal with video data */
static void sur40_process_video(struct sur40_state *sur40)
{

	struct sur40_image_header *img = (void *)(sur40->bulk_in_buffer);
	struct sur40_buffer *new_buf;
	struct usb_sg_request sgr;
	struct sg_table *sgt;
	int result, bulk_read;

	if (!vb2_start_streaming_called(&sur40->queue))
		return;

	/* get a new buffer from the list */
	spin_lock(&sur40->qlock);
	if (list_empty(&sur40->buf_list)) {
		dev_dbg(sur40->dev, "buffer queue empty\n");
		spin_unlock(&sur40->qlock);
		return;
	}
	new_buf = list_entry(sur40->buf_list.next, struct sur40_buffer, list);
	list_del(&new_buf->list);
	spin_unlock(&sur40->qlock);

	/* retrieve data via bulk read */
	result = usb_bulk_msg(sur40->usbdev,
			usb_rcvbulkpipe(sur40->usbdev, VIDEO_ENDPOINT),
			sur40->bulk_in_buffer, sur40->bulk_in_size,
			&bulk_read, 1000);

	if (result < 0) {
		dev_err(sur40->dev, "error in usb_bulk_read\n");
		goto err_poll;
	}

	if (bulk_read != sizeof(struct sur40_image_header)) {
		dev_err(sur40->dev, "received %d bytes (%zd expected)\n",
			bulk_read, sizeof(struct sur40_image_header));
		goto err_poll;
	}

	if (le32_to_cpu(img->magic) != VIDEO_HEADER_MAGIC) {
		dev_err(sur40->dev, "image magic mismatch\n");
		goto err_poll;
	}

	if (le32_to_cpu(img->size) != sur40_video_format.sizeimage) {
		dev_err(sur40->dev, "image size mismatch\n");
		goto err_poll;
	}

	sgt = vb2_dma_sg_plane_desc(&new_buf->vb, 0);

	result = usb_sg_init(&sgr, sur40->usbdev,
		usb_rcvbulkpipe(sur40->usbdev, VIDEO_ENDPOINT), 0,
		sgt->sgl, sgt->nents, sur40_video_format.sizeimage, 0);
	if (result < 0) {
		dev_err(sur40->dev, "error %d in usb_sg_init\n", result);
		goto err_poll;
	}

	usb_sg_wait(&sgr);
	if (sgr.status < 0) {
		dev_err(sur40->dev, "error %d in usb_sg_wait\n", sgr.status);
		goto err_poll;
	}

	/* mark as finished */
	v4l2_get_timestamp(&new_buf->vb.v4l2_buf.timestamp);
	new_buf->vb.v4l2_buf.sequence = sur40->sequence++;
	new_buf->vb.v4l2_buf.field = V4L2_FIELD_NONE;
	vb2_buffer_done(&new_buf->vb, VB2_BUF_STATE_DONE);
	return;

err_poll:
	vb2_buffer_done(&new_buf->vb, VB2_BUF_STATE_ERROR);
}

/* Initialize input device parameters. */
static void sur40_input_setup(struct input_dev *input_dev)
{
	__set_bit(EV_KEY, input_dev->evbit);
	__set_bit(EV_ABS, input_dev->evbit);

	input_set_abs_params(input_dev, ABS_MT_POSITION_X,
			     0, SENSOR_RES_X, 0, 0);
	input_set_abs_params(input_dev, ABS_MT_POSITION_Y,
			     0, SENSOR_RES_Y, 0, 0);

	input_set_abs_params(input_dev, ABS_MT_TOOL_X,
			     0, SENSOR_RES_X, 0, 0);
	input_set_abs_params(input_dev, ABS_MT_TOOL_Y,
			     0, SENSOR_RES_Y, 0, 0);

	/* max value unknown, but major/minor axis
	 * can never be larger than screen */
	input_set_abs_params(input_dev, ABS_MT_TOUCH_MAJOR,
			     0, SENSOR_RES_X, 0, 0);
	input_set_abs_params(input_dev, ABS_MT_TOUCH_MINOR,
			     0, SENSOR_RES_Y, 0, 0);

	input_set_abs_params(input_dev, ABS_MT_ORIENTATION, 0, 1, 0, 0);

	input_mt_init_slots(input_dev, MAX_CONTACTS,
			    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
}

/* Check candidate USB interface. */
static int sur40_probe(struct usb_interface *interface,
		       const struct usb_device_id *id)
{
	struct usb_device *usbdev = interface_to_usbdev(interface);
	struct sur40_state *sur40;
	struct usb_host_interface *iface_desc;
	struct usb_endpoint_descriptor *endpoint;
	struct input_polled_dev *poll_dev;
	int error;

	/* Check if we really have the right interface. */
	iface_desc = &interface->altsetting[0];
	if (iface_desc->desc.bInterfaceClass != 0xFF)
		return -ENODEV;

	/* Use endpoint #4 (0x86). */
	endpoint = &iface_desc->endpoint[4].desc;
	if (endpoint->bEndpointAddress != TOUCH_ENDPOINT)
		return -ENODEV;

	/* Allocate memory for our device state and initialize it. */
	sur40 = kzalloc(sizeof(struct sur40_state), GFP_KERNEL);
	if (!sur40)
		return -ENOMEM;

	poll_dev = input_allocate_polled_device();
	if (!poll_dev) {
		error = -ENOMEM;
		goto err_free_dev;
	}

	/* initialize locks/lists */
	INIT_LIST_HEAD(&sur40->buf_list);
	spin_lock_init(&sur40->qlock);
	mutex_init(&sur40->lock);

	/* Set up polled input device control structure */
	poll_dev->private = sur40;
	poll_dev->poll_interval = POLL_INTERVAL;
	poll_dev->open = sur40_open;
	poll_dev->poll = sur40_poll;
	poll_dev->close = sur40_close;

	/* Set up regular input device structure */
	sur40_input_setup(poll_dev->input);

	poll_dev->input->name = DRIVER_LONG;
	usb_to_input_id(usbdev, &poll_dev->input->id);
	usb_make_path(usbdev, sur40->phys, sizeof(sur40->phys));
	strlcat(sur40->phys, "/input0", sizeof(sur40->phys));
	poll_dev->input->phys = sur40->phys;
	poll_dev->input->dev.parent = &interface->dev;

	sur40->usbdev = usbdev;
	sur40->dev = &interface->dev;
	sur40->input = poll_dev;

	/* use the bulk-in endpoint tested above */
	sur40->bulk_in_size = usb_endpoint_maxp(endpoint);
	sur40->bulk_in_epaddr = endpoint->bEndpointAddress;
	sur40->bulk_in_buffer = kmalloc(sur40->bulk_in_size, GFP_KERNEL);
	if (!sur40->bulk_in_buffer) {
		dev_err(&interface->dev, "Unable to allocate input buffer.");
		error = -ENOMEM;
		goto err_free_polldev;
	}

	/* register the polled input device */
	error = input_register_polled_device(poll_dev);
	if (error) {
		dev_err(&interface->dev,
			"Unable to register polled input device.");
		goto err_free_buffer;
	}

	/* register the video master device */
	snprintf(sur40->v4l2.name, sizeof(sur40->v4l2.name), "%s", DRIVER_LONG);
	error = v4l2_device_register(sur40->dev, &sur40->v4l2);
	if (error) {
		dev_err(&interface->dev,
			"Unable to register video master device.");
		goto err_unreg_v4l2;
	}

	/* initialize the lock and subdevice */
	sur40->queue = sur40_queue;
	sur40->queue.drv_priv = sur40;
	sur40->queue.lock = &sur40->lock;

	/* initialize the queue */
	error = vb2_queue_init(&sur40->queue);
	if (error)
		goto err_unreg_v4l2;

	sur40->alloc_ctx = vb2_dma_sg_init_ctx(sur40->dev);
	if (IS_ERR(sur40->alloc_ctx)) {
		dev_err(sur40->dev, "Can't allocate buffer context");
		goto err_unreg_v4l2;
	}

	sur40->vdev = sur40_video_device;
	sur40->vdev.v4l2_dev = &sur40->v4l2;
	sur40->vdev.lock = &sur40->lock;
	sur40->vdev.queue = &sur40->queue;
	video_set_drvdata(&sur40->vdev, sur40);

	error = video_register_device(&sur40->vdev, VFL_TYPE_GRABBER, -1);
	if (error) {
		dev_err(&interface->dev,
			"Unable to register video subdevice.");
		goto err_unreg_video;
	}

	/* we can register the device now, as it is ready */
	usb_set_intfdata(interface, sur40);
	dev_dbg(&interface->dev, "%s is now attached\n", DRIVER_DESC);

	return 0;

err_unreg_video:
	video_unregister_device(&sur40->vdev);
err_unreg_v4l2:
	v4l2_device_unregister(&sur40->v4l2);
err_free_buffer:
	kfree(sur40->bulk_in_buffer);
err_free_polldev:
	input_free_polled_device(sur40->input);
err_free_dev:
	kfree(sur40);

	return error;
}

/* Unregister device & clean up. */
static void sur40_disconnect(struct usb_interface *interface)
{
	struct sur40_state *sur40 = usb_get_intfdata(interface);

	video_unregister_device(&sur40->vdev);
	v4l2_device_unregister(&sur40->v4l2);
	vb2_dma_sg_cleanup_ctx(sur40->alloc_ctx);

	input_unregister_polled_device(sur40->input);
	input_free_polled_device(sur40->input);
	kfree(sur40->bulk_in_buffer);
	kfree(sur40);

	usb_set_intfdata(interface, NULL);
	dev_dbg(&interface->dev, "%s is now disconnected\n", DRIVER_DESC);
}

/*
 * 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 sur40_queue_setup(struct vb2_queue *q, const struct v4l2_format *fmt,
		       unsigned int *nbuffers, unsigned int *nplanes,
		       unsigned int sizes[], void *alloc_ctxs[])
{
	struct sur40_state *sur40 = vb2_get_drv_priv(q);

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

	if (fmt && fmt->fmt.pix.sizeimage < sur40_video_format.sizeimage)
		return -EINVAL;

	*nplanes = 1;
	sizes[0] = fmt ? fmt->fmt.pix.sizeimage : sur40_video_format.sizeimage;
	alloc_ctxs[0] = sur40->alloc_ctx;

	return 0;
}

/*
 * Prepare the buffer for queueing to the DMA engine: check and set the
 * payload size.
 */
static int sur40_buffer_prepare(struct vb2_buffer *vb)
{
	struct sur40_state *sur40 = vb2_get_drv_priv(vb->vb2_queue);
	unsigned long size = sur40_video_format.sizeimage;

	if (vb2_plane_size(vb, 0) < size) {
		dev_err(&sur40->usbdev->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 sur40_buffer_queue(struct vb2_buffer *vb)
{
	struct sur40_state *sur40 = vb2_get_drv_priv(vb->vb2_queue);
	struct sur40_buffer *buf = (struct sur40_buffer *)vb;

	spin_lock(&sur40->qlock);
	list_add_tail(&buf->list, &sur40->buf_list);
	spin_unlock(&sur40->qlock);
}

static void return_all_buffers(struct sur40_state *sur40,
			       enum vb2_buffer_state state)
{
	struct sur40_buffer *buf, *node;

	spin_lock(&sur40->qlock);
	list_for_each_entry_safe(buf, node, &sur40->buf_list, list) {
		vb2_buffer_done(&buf->vb, state);
		list_del(&buf->list);
	}
	spin_unlock(&sur40->qlock);
}

/*
 * 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 sur40_start_streaming(struct vb2_queue *vq, unsigned int count)
{
	struct sur40_state *sur40 = vb2_get_drv_priv(vq);

	sur40->sequence = 0;
	return 0;
}

/*
 * 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 sur40_stop_streaming(struct vb2_queue *vq)
{
	struct sur40_state *sur40 = vb2_get_drv_priv(vq);

	/* Release all active buffers */
	return_all_buffers(sur40, VB2_BUF_STATE_ERROR);
}

/* V4L ioctl */
static int sur40_vidioc_querycap(struct file *file, void *priv,
				 struct v4l2_capability *cap)
{
	struct sur40_state *sur40 = video_drvdata(file);

	strlcpy(cap->driver, DRIVER_SHORT, sizeof(cap->driver));
	strlcpy(cap->card, DRIVER_LONG, sizeof(cap->card));
	usb_make_path(sur40->usbdev, cap->bus_info, sizeof(cap->bus_info));
	cap->device_caps = V4L2_CAP_VIDEO_CAPTURE |
		V4L2_CAP_READWRITE |
		V4L2_CAP_STREAMING;
	cap->capabilities = cap->device_caps | V4L2_CAP_DEVICE_CAPS;
	return 0;
}

static int sur40_vidioc_enum_input(struct file *file, void *priv,
				   struct v4l2_input *i)
{
	if (i->index != 0)
		return -EINVAL;
	i->type = V4L2_INPUT_TYPE_CAMERA;
	i->std = V4L2_STD_UNKNOWN;
	strlcpy(i->name, "In-Cell Sensor", sizeof(i->name));
	i->capabilities = 0;
	return 0;
}

static int sur40_vidioc_s_input(struct file *file, void *priv, unsigned int i)
{
	return (i == 0) ? 0 : -EINVAL;
}

static int sur40_vidioc_g_input(struct file *file, void *priv, unsigned int *i)
{
	*i = 0;
	return 0;
}

static int sur40_vidioc_fmt(struct file *file, void *priv,
			    struct v4l2_format *f)
{
	f->fmt.pix = sur40_video_format;
	return 0;
}

static int sur40_vidioc_enum_fmt(struct file *file, void *priv,
				 struct v4l2_fmtdesc *f)
{
	if (f->index != 0)
		return -EINVAL;
	strlcpy(f->description, "8-bit greyscale", sizeof(f->description));
	f->pixelformat = V4L2_PIX_FMT_GREY;
	f->flags = 0;
	return 0;
}

static const struct usb_device_id sur40_table[] = {
	{ USB_DEVICE(ID_MICROSOFT, ID_SUR40) },  /* Samsung SUR40 */
	{ }                                      /* terminating null entry */
};
MODULE_DEVICE_TABLE(usb, sur40_table);

/* V4L2 structures */
static const struct vb2_ops sur40_queue_ops = {
	.queue_setup		= sur40_queue_setup,
	.buf_prepare		= sur40_buffer_prepare,
	.buf_queue		= sur40_buffer_queue,
	.start_streaming	= sur40_start_streaming,
	.stop_streaming		= sur40_stop_streaming,
	.wait_prepare		= vb2_ops_wait_prepare,
	.wait_finish		= vb2_ops_wait_finish,
};

static const struct vb2_queue sur40_queue = {
	.type = V4L2_BUF_TYPE_VIDEO_CAPTURE,
	/*
	 * VB2_USERPTR in currently not enabled: passing a user pointer to
	 * dma-sg will result in segment sizes that are not a multiple of
	 * 512 bytes, which is required by the host controller.
	*/
	.io_modes = VB2_MMAP | VB2_READ | VB2_DMABUF,
	.buf_struct_size = sizeof(struct sur40_buffer),
	.ops = &sur40_queue_ops,
	.mem_ops = &vb2_dma_sg_memops,
	.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC,
	.min_buffers_needed = 3,
};

static const struct v4l2_file_operations sur40_video_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,
};

static const struct v4l2_ioctl_ops sur40_video_ioctl_ops = {

	.vidioc_querycap	= sur40_vidioc_querycap,

	.vidioc_enum_fmt_vid_cap = sur40_vidioc_enum_fmt,
	.vidioc_try_fmt_vid_cap	= sur40_vidioc_fmt,
	.vidioc_s_fmt_vid_cap	= sur40_vidioc_fmt,
	.vidioc_g_fmt_vid_cap	= sur40_vidioc_fmt,

	.vidioc_enum_input	= sur40_vidioc_enum_input,
	.vidioc_g_input		= sur40_vidioc_g_input,
	.vidioc_s_input		= sur40_vidioc_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,
};

static const struct video_device sur40_video_device = {
	.name = DRIVER_LONG,
	.fops = &sur40_video_fops,
	.ioctl_ops = &sur40_video_ioctl_ops,
	.release = video_device_release_empty,
};

static const struct v4l2_pix_format sur40_video_format = {
	.pixelformat = V4L2_PIX_FMT_GREY,
	.width  = SENSOR_RES_X / 2,
	.height = SENSOR_RES_Y / 2,
	.field = V4L2_FIELD_NONE,
	.colorspace = V4L2_COLORSPACE_SRGB,
	.bytesperline = SENSOR_RES_X / 2,
	.sizeimage = (SENSOR_RES_X/2) * (SENSOR_RES_Y/2),
};

/* USB-specific object needed to register this driver with the USB subsystem. */
static struct usb_driver sur40_driver = {
	.name = DRIVER_SHORT,
	.probe = sur40_probe,
	.disconnect = sur40_disconnect,
	.id_table = sur40_table,
};

module_usb_driver(sur40_driver);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");