summaryrefslogtreecommitdiff
path: root/drivers/media/video/mt9t031.c
blob: d9c7c2fd698aaf215d6ab7f475142695667e6c28 (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
/*
 * Driver for MT9T031 CMOS Image Sensor from Micron
 *
 * Copyright (C) 2008, Guennadi Liakhovetski, DENX Software Engineering <lg@denx.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/videodev2.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/log2.h>

#include <media/v4l2-common.h>
#include <media/v4l2-chip-ident.h>
#include <media/soc_camera.h>

/* mt9t031 i2c address 0x5d
 * The platform has to define i2c_board_info
 * and call i2c_register_board_info() */

/* mt9t031 selected register addresses */
#define MT9T031_CHIP_VERSION		0x00
#define MT9T031_ROW_START		0x01
#define MT9T031_COLUMN_START		0x02
#define MT9T031_WINDOW_HEIGHT		0x03
#define MT9T031_WINDOW_WIDTH		0x04
#define MT9T031_HORIZONTAL_BLANKING	0x05
#define MT9T031_VERTICAL_BLANKING	0x06
#define MT9T031_OUTPUT_CONTROL		0x07
#define MT9T031_SHUTTER_WIDTH_UPPER	0x08
#define MT9T031_SHUTTER_WIDTH		0x09
#define MT9T031_PIXEL_CLOCK_CONTROL	0x0a
#define MT9T031_FRAME_RESTART		0x0b
#define MT9T031_SHUTTER_DELAY		0x0c
#define MT9T031_RESET			0x0d
#define MT9T031_READ_MODE_1		0x1e
#define MT9T031_READ_MODE_2		0x20
#define MT9T031_READ_MODE_3		0x21
#define MT9T031_ROW_ADDRESS_MODE	0x22
#define MT9T031_COLUMN_ADDRESS_MODE	0x23
#define MT9T031_GLOBAL_GAIN		0x35
#define MT9T031_CHIP_ENABLE		0xF8

#define MT9T031_MAX_HEIGHT		1536
#define MT9T031_MAX_WIDTH		2048
#define MT9T031_MIN_HEIGHT		2
#define MT9T031_MIN_WIDTH		2
#define MT9T031_HORIZONTAL_BLANK	142
#define MT9T031_VERTICAL_BLANK		25
#define MT9T031_COLUMN_SKIP		32
#define MT9T031_ROW_SKIP		20

#define MT9T031_BUS_PARAM	(SOCAM_PCLK_SAMPLE_RISING |	\
	SOCAM_PCLK_SAMPLE_FALLING | SOCAM_HSYNC_ACTIVE_HIGH |	\
	SOCAM_VSYNC_ACTIVE_HIGH | SOCAM_DATA_ACTIVE_HIGH |	\
	SOCAM_MASTER | SOCAM_DATAWIDTH_10)

static const struct soc_camera_data_format mt9t031_colour_formats[] = {
	{
		.name		= "Bayer (sRGB) 10 bit",
		.depth		= 10,
		.fourcc		= V4L2_PIX_FMT_SGRBG10,
		.colorspace	= V4L2_COLORSPACE_SRGB,
	}
};

struct mt9t031 {
	int model;	/* V4L2_IDENT_MT9T031* codes from v4l2-chip-ident.h */
	unsigned char autoexposure;
	u16 xskip;
	u16 yskip;
};

static int reg_read(struct i2c_client *client, const u8 reg)
{
	s32 data = i2c_smbus_read_word_data(client, reg);
	return data < 0 ? data : swab16(data);
}

static int reg_write(struct i2c_client *client, const u8 reg,
		     const u16 data)
{
	return i2c_smbus_write_word_data(client, reg, swab16(data));
}

static int reg_set(struct i2c_client *client, const u8 reg,
		   const u16 data)
{
	int ret;

	ret = reg_read(client, reg);
	if (ret < 0)
		return ret;
	return reg_write(client, reg, ret | data);
}

static int reg_clear(struct i2c_client *client, const u8 reg,
		     const u16 data)
{
	int ret;

	ret = reg_read(client, reg);
	if (ret < 0)
		return ret;
	return reg_write(client, reg, ret & ~data);
}

static int set_shutter(struct i2c_client *client, const u32 data)
{
	int ret;

	ret = reg_write(client, MT9T031_SHUTTER_WIDTH_UPPER, data >> 16);

	if (ret >= 0)
		ret = reg_write(client, MT9T031_SHUTTER_WIDTH, data & 0xffff);

	return ret;
}

static int get_shutter(struct i2c_client *client, u32 *data)
{
	int ret;

	ret = reg_read(client, MT9T031_SHUTTER_WIDTH_UPPER);
	*data = ret << 16;

	if (ret >= 0)
		ret = reg_read(client, MT9T031_SHUTTER_WIDTH);
	*data |= ret & 0xffff;

	return ret < 0 ? ret : 0;
}

static int mt9t031_init(struct soc_camera_device *icd)
{
	struct i2c_client *client = to_i2c_client(to_soc_camera_control(icd));
	struct soc_camera_link *icl = to_soc_camera_link(icd);
	int ret;

	if (icl->power) {
		ret = icl->power(&client->dev, 1);
		if (ret < 0) {
			dev_err(icd->vdev->parent,
				"Platform failed to power-on the camera.\n");
			return ret;
		}
	}

	/* Disable chip output, synchronous option update */
	ret = reg_write(client, MT9T031_RESET, 1);
	if (ret >= 0)
		ret = reg_write(client, MT9T031_RESET, 0);
	if (ret >= 0)
		ret = reg_clear(client, MT9T031_OUTPUT_CONTROL, 2);

	if (ret < 0 && icl->power)
		icl->power(&client->dev, 0);

	return ret >= 0 ? 0 : -EIO;
}

static int mt9t031_release(struct soc_camera_device *icd)
{
	struct i2c_client *client = to_i2c_client(to_soc_camera_control(icd));
	struct soc_camera_link *icl = to_soc_camera_link(icd);

	/* Disable the chip */
	reg_clear(client, MT9T031_OUTPUT_CONTROL, 2);

	if (icl->power)
		icl->power(&client->dev, 0);

	return 0;
}

static int mt9t031_start_capture(struct soc_camera_device *icd)
{
	struct i2c_client *client = to_i2c_client(to_soc_camera_control(icd));

	/* Switch to master "normal" mode */
	if (reg_set(client, MT9T031_OUTPUT_CONTROL, 2) < 0)
		return -EIO;
	return 0;
}

static int mt9t031_stop_capture(struct soc_camera_device *icd)
{
	struct i2c_client *client = to_i2c_client(to_soc_camera_control(icd));

	/* Stop sensor readout */
	if (reg_clear(client, MT9T031_OUTPUT_CONTROL, 2) < 0)
		return -EIO;
	return 0;
}

static int mt9t031_set_bus_param(struct soc_camera_device *icd,
				 unsigned long flags)
{
	struct i2c_client *client = to_i2c_client(to_soc_camera_control(icd));

	/* The caller should have queried our parameters, check anyway */
	if (flags & ~MT9T031_BUS_PARAM)
		return -EINVAL;

	if (flags & SOCAM_PCLK_SAMPLE_FALLING)
		reg_clear(client, MT9T031_PIXEL_CLOCK_CONTROL, 0x8000);
	else
		reg_set(client, MT9T031_PIXEL_CLOCK_CONTROL, 0x8000);

	return 0;
}

static unsigned long mt9t031_query_bus_param(struct soc_camera_device *icd)
{
	struct soc_camera_link *icl = to_soc_camera_link(icd);

	return soc_camera_apply_sensor_flags(icl, MT9T031_BUS_PARAM);
}

/* Round up minima and round down maxima */
static void recalculate_limits(struct soc_camera_device *icd,
			       u16 xskip, u16 yskip)
{
	icd->x_min = (MT9T031_COLUMN_SKIP + xskip - 1) / xskip;
	icd->y_min = (MT9T031_ROW_SKIP + yskip - 1) / yskip;
	icd->width_min = (MT9T031_MIN_WIDTH + xskip - 1) / xskip;
	icd->height_min = (MT9T031_MIN_HEIGHT + yskip - 1) / yskip;
	icd->width_max = MT9T031_MAX_WIDTH / xskip;
	icd->height_max = MT9T031_MAX_HEIGHT / yskip;
}

static int mt9t031_set_params(struct soc_camera_device *icd,
			      struct v4l2_rect *rect, u16 xskip, u16 yskip)
{
	struct i2c_client *client = to_i2c_client(to_soc_camera_control(icd));
	struct mt9t031 *mt9t031 = i2c_get_clientdata(client);
	int ret;
	u16 xbin, ybin, width, height, left, top;
	const u16 hblank = MT9T031_HORIZONTAL_BLANK,
		vblank = MT9T031_VERTICAL_BLANK;

	/* Make sure we don't exceed sensor limits */
	if (rect->left + rect->width > icd->width_max)
		rect->left = (icd->width_max - rect->width) / 2 + icd->x_min;

	if (rect->top + rect->height > icd->height_max)
		rect->top = (icd->height_max - rect->height) / 2 + icd->y_min;

	width = rect->width * xskip;
	height = rect->height * yskip;
	left = rect->left * xskip;
	top = rect->top * yskip;

	xbin = min(xskip, (u16)3);
	ybin = min(yskip, (u16)3);

	dev_dbg(&icd->dev, "xskip %u, width %u/%u, yskip %u, height %u/%u\n",
		xskip, width, rect->width, yskip, height, rect->height);

	/* Could just do roundup(rect->left, [xy]bin * 2); but this is cheaper */
	switch (xbin) {
	case 2:
		left = (left + 3) & ~3;
		break;
	case 3:
		left = roundup(left, 6);
	}

	switch (ybin) {
	case 2:
		top = (top + 3) & ~3;
		break;
	case 3:
		top = roundup(top, 6);
	}

	/* Disable register update, reconfigure atomically */
	ret = reg_set(client, MT9T031_OUTPUT_CONTROL, 1);
	if (ret < 0)
		return ret;

	/* Blanking and start values - default... */
	ret = reg_write(client, MT9T031_HORIZONTAL_BLANKING, hblank);
	if (ret >= 0)
		ret = reg_write(client, MT9T031_VERTICAL_BLANKING, vblank);

	if (yskip != mt9t031->yskip || xskip != mt9t031->xskip) {
		/* Binning, skipping */
		if (ret >= 0)
			ret = reg_write(client, MT9T031_COLUMN_ADDRESS_MODE,
					((xbin - 1) << 4) | (xskip - 1));
		if (ret >= 0)
			ret = reg_write(client, MT9T031_ROW_ADDRESS_MODE,
					((ybin - 1) << 4) | (yskip - 1));
	}
	dev_dbg(&icd->dev, "new physical left %u, top %u\n", left, top);

	/* The caller provides a supported format, as guaranteed by
	 * icd->try_fmt_cap(), soc_camera_s_crop() and soc_camera_cropcap() */
	if (ret >= 0)
		ret = reg_write(client, MT9T031_COLUMN_START, left);
	if (ret >= 0)
		ret = reg_write(client, MT9T031_ROW_START, top);
	if (ret >= 0)
		ret = reg_write(client, MT9T031_WINDOW_WIDTH, width - 1);
	if (ret >= 0)
		ret = reg_write(client, MT9T031_WINDOW_HEIGHT,
				height + icd->y_skip_top - 1);
	if (ret >= 0 && mt9t031->autoexposure) {
		ret = set_shutter(client, height + icd->y_skip_top + vblank);
		if (ret >= 0) {
			const u32 shutter_max = MT9T031_MAX_HEIGHT + vblank;
			const struct v4l2_queryctrl *qctrl =
				soc_camera_find_qctrl(icd->ops,
						      V4L2_CID_EXPOSURE);
			icd->exposure = (shutter_max / 2 + (height +
					 icd->y_skip_top + vblank - 1) *
					 (qctrl->maximum - qctrl->minimum)) /
				shutter_max + qctrl->minimum;
		}
	}

	/* Re-enable register update, commit all changes */
	if (ret >= 0)
		ret = reg_clear(client, MT9T031_OUTPUT_CONTROL, 1);

	return ret < 0 ? ret : 0;
}

static int mt9t031_set_crop(struct soc_camera_device *icd,
			    struct v4l2_rect *rect)
{
	struct i2c_client *client = to_i2c_client(to_soc_camera_control(icd));
	struct mt9t031 *mt9t031 = i2c_get_clientdata(client);

	/* CROP - no change in scaling, or in limits */
	return mt9t031_set_params(icd, rect, mt9t031->xskip, mt9t031->yskip);
}

static int mt9t031_set_fmt(struct soc_camera_device *icd,
			   struct v4l2_format *f)
{
	struct i2c_client *client = to_i2c_client(to_soc_camera_control(icd));
	struct mt9t031 *mt9t031 = i2c_get_clientdata(client);
	int ret;
	u16 xskip, yskip;
	struct v4l2_rect rect = {
		.left	= icd->x_current,
		.top	= icd->y_current,
		.width	= f->fmt.pix.width,
		.height	= f->fmt.pix.height,
	};

	/*
	 * try_fmt has put rectangle within limits.
	 * S_FMT - use binning and skipping for scaling, recalculate
	 * limits, used for cropping
	 */
	/* Is this more optimal than just a division? */
	for (xskip = 8; xskip > 1; xskip--)
		if (rect.width * xskip <= MT9T031_MAX_WIDTH)
			break;

	for (yskip = 8; yskip > 1; yskip--)
		if (rect.height * yskip <= MT9T031_MAX_HEIGHT)
			break;

	recalculate_limits(icd, xskip, yskip);

	ret = mt9t031_set_params(icd, &rect, xskip, yskip);
	if (!ret) {
		mt9t031->xskip = xskip;
		mt9t031->yskip = yskip;
	}

	return ret;
}

static int mt9t031_try_fmt(struct soc_camera_device *icd,
			   struct v4l2_format *f)
{
	struct v4l2_pix_format *pix = &f->fmt.pix;

	v4l_bound_align_image(
		&pix->width, MT9T031_MIN_WIDTH, MT9T031_MAX_WIDTH, 1,
		&pix->height, MT9T031_MIN_HEIGHT, MT9T031_MAX_HEIGHT, 1, 0);

	return 0;
}

static int mt9t031_get_chip_id(struct soc_camera_device *icd,
			       struct v4l2_dbg_chip_ident *id)
{
	struct i2c_client *client = to_i2c_client(to_soc_camera_control(icd));
	struct mt9t031 *mt9t031 = i2c_get_clientdata(client);

	if (id->match.type != V4L2_CHIP_MATCH_I2C_ADDR)
		return -EINVAL;

	if (id->match.addr != client->addr)
		return -ENODEV;

	id->ident	= mt9t031->model;
	id->revision	= 0;

	return 0;
}

#ifdef CONFIG_VIDEO_ADV_DEBUG
static int mt9t031_get_register(struct soc_camera_device *icd,
				struct v4l2_dbg_register *reg)
{
	struct i2c_client *client = to_i2c_client(to_soc_camera_control(icd));

	if (reg->match.type != V4L2_CHIP_MATCH_I2C_ADDR || reg->reg > 0xff)
		return -EINVAL;

	if (reg->match.addr != client->addr)
		return -ENODEV;

	reg->val = reg_read(client, reg->reg);

	if (reg->val > 0xffff)
		return -EIO;

	return 0;
}

static int mt9t031_set_register(struct soc_camera_device *icd,
				struct v4l2_dbg_register *reg)
{
	struct i2c_client *client = to_i2c_client(to_soc_camera_control(icd));

	if (reg->match.type != V4L2_CHIP_MATCH_I2C_ADDR || reg->reg > 0xff)
		return -EINVAL;

	if (reg->match.addr != client->addr)
		return -ENODEV;

	if (reg_write(client, reg->reg, reg->val) < 0)
		return -EIO;

	return 0;
}
#endif

static const struct v4l2_queryctrl mt9t031_controls[] = {
	{
		.id		= V4L2_CID_VFLIP,
		.type		= V4L2_CTRL_TYPE_BOOLEAN,
		.name		= "Flip Vertically",
		.minimum	= 0,
		.maximum	= 1,
		.step		= 1,
		.default_value	= 0,
	}, {
		.id		= V4L2_CID_HFLIP,
		.type		= V4L2_CTRL_TYPE_BOOLEAN,
		.name		= "Flip Horizontally",
		.minimum	= 0,
		.maximum	= 1,
		.step		= 1,
		.default_value	= 0,
	}, {
		.id		= V4L2_CID_GAIN,
		.type		= V4L2_CTRL_TYPE_INTEGER,
		.name		= "Gain",
		.minimum	= 0,
		.maximum	= 127,
		.step		= 1,
		.default_value	= 64,
		.flags		= V4L2_CTRL_FLAG_SLIDER,
	}, {
		.id		= V4L2_CID_EXPOSURE,
		.type		= V4L2_CTRL_TYPE_INTEGER,
		.name		= "Exposure",
		.minimum	= 1,
		.maximum	= 255,
		.step		= 1,
		.default_value	= 255,
		.flags		= V4L2_CTRL_FLAG_SLIDER,
	}, {
		.id		= V4L2_CID_EXPOSURE_AUTO,
		.type		= V4L2_CTRL_TYPE_BOOLEAN,
		.name		= "Automatic Exposure",
		.minimum	= 0,
		.maximum	= 1,
		.step		= 1,
		.default_value	= 1,
	}
};

static int mt9t031_get_control(struct soc_camera_device *, struct v4l2_control *);
static int mt9t031_set_control(struct soc_camera_device *, struct v4l2_control *);

static struct soc_camera_ops mt9t031_ops = {
	.owner			= THIS_MODULE,
	.init			= mt9t031_init,
	.release		= mt9t031_release,
	.start_capture		= mt9t031_start_capture,
	.stop_capture		= mt9t031_stop_capture,
	.set_crop		= mt9t031_set_crop,
	.set_fmt		= mt9t031_set_fmt,
	.try_fmt		= mt9t031_try_fmt,
	.set_bus_param		= mt9t031_set_bus_param,
	.query_bus_param	= mt9t031_query_bus_param,
	.controls		= mt9t031_controls,
	.num_controls		= ARRAY_SIZE(mt9t031_controls),
	.get_control		= mt9t031_get_control,
	.set_control		= mt9t031_set_control,
	.get_chip_id		= mt9t031_get_chip_id,
#ifdef CONFIG_VIDEO_ADV_DEBUG
	.get_register		= mt9t031_get_register,
	.set_register		= mt9t031_set_register,
#endif
};

static int mt9t031_get_control(struct soc_camera_device *icd, struct v4l2_control *ctrl)
{
	struct i2c_client *client = to_i2c_client(to_soc_camera_control(icd));
	struct mt9t031 *mt9t031 = i2c_get_clientdata(client);
	int data;

	switch (ctrl->id) {
	case V4L2_CID_VFLIP:
		data = reg_read(client, MT9T031_READ_MODE_2);
		if (data < 0)
			return -EIO;
		ctrl->value = !!(data & 0x8000);
		break;
	case V4L2_CID_HFLIP:
		data = reg_read(client, MT9T031_READ_MODE_2);
		if (data < 0)
			return -EIO;
		ctrl->value = !!(data & 0x4000);
		break;
	case V4L2_CID_EXPOSURE_AUTO:
		ctrl->value = mt9t031->autoexposure;
		break;
	}
	return 0;
}

static int mt9t031_set_control(struct soc_camera_device *icd, struct v4l2_control *ctrl)
{
	struct i2c_client *client = to_i2c_client(to_soc_camera_control(icd));
	struct mt9t031 *mt9t031 = i2c_get_clientdata(client);
	const struct v4l2_queryctrl *qctrl;
	int data;

	qctrl = soc_camera_find_qctrl(&mt9t031_ops, ctrl->id);

	if (!qctrl)
		return -EINVAL;

	switch (ctrl->id) {
	case V4L2_CID_VFLIP:
		if (ctrl->value)
			data = reg_set(client, MT9T031_READ_MODE_2, 0x8000);
		else
			data = reg_clear(client, MT9T031_READ_MODE_2, 0x8000);
		if (data < 0)
			return -EIO;
		break;
	case V4L2_CID_HFLIP:
		if (ctrl->value)
			data = reg_set(client, MT9T031_READ_MODE_2, 0x4000);
		else
			data = reg_clear(client, MT9T031_READ_MODE_2, 0x4000);
		if (data < 0)
			return -EIO;
		break;
	case V4L2_CID_GAIN:
		if (ctrl->value > qctrl->maximum || ctrl->value < qctrl->minimum)
			return -EINVAL;
		/* See Datasheet Table 7, Gain settings. */
		if (ctrl->value <= qctrl->default_value) {
			/* Pack it into 0..1 step 0.125, register values 0..8 */
			unsigned long range = qctrl->default_value - qctrl->minimum;
			data = ((ctrl->value - qctrl->minimum) * 8 + range / 2) / range;

			dev_dbg(&icd->dev, "Setting gain %d\n", data);
			data = reg_write(client, MT9T031_GLOBAL_GAIN, data);
			if (data < 0)
				return -EIO;
		} else {
			/* Pack it into 1.125..128 variable step, register values 9..0x7860 */
			/* We assume qctrl->maximum - qctrl->default_value - 1 > 0 */
			unsigned long range = qctrl->maximum - qctrl->default_value - 1;
			/* calculated gain: map 65..127 to 9..1024 step 0.125 */
			unsigned long gain = ((ctrl->value - qctrl->default_value - 1) *
					       1015 + range / 2) / range + 9;

			if (gain <= 32)		/* calculated gain 9..32 -> 9..32 */
				data = gain;
			else if (gain <= 64)	/* calculated gain 33..64 -> 0x51..0x60 */
				data = ((gain - 32) * 16 + 16) / 32 + 80;
			else
				/* calculated gain 65..1024 -> (1..120) << 8 + 0x60 */
				data = (((gain - 64 + 7) * 32) & 0xff00) | 0x60;

			dev_dbg(&icd->dev, "Setting gain from 0x%x to 0x%x\n",
				reg_read(client, MT9T031_GLOBAL_GAIN), data);
			data = reg_write(client, MT9T031_GLOBAL_GAIN, data);
			if (data < 0)
				return -EIO;
		}

		/* Success */
		icd->gain = ctrl->value;
		break;
	case V4L2_CID_EXPOSURE:
		/* mt9t031 has maximum == default */
		if (ctrl->value > qctrl->maximum || ctrl->value < qctrl->minimum)
			return -EINVAL;
		else {
			const unsigned long range = qctrl->maximum - qctrl->minimum;
			const u32 shutter = ((ctrl->value - qctrl->minimum) * 1048 +
					     range / 2) / range + 1;
			u32 old;

			get_shutter(client, &old);
			dev_dbg(&icd->dev, "Setting shutter width from %u to %u\n",
				old, shutter);
			if (set_shutter(client, shutter) < 0)
				return -EIO;
			icd->exposure = ctrl->value;
			mt9t031->autoexposure = 0;
		}
		break;
	case V4L2_CID_EXPOSURE_AUTO:
		if (ctrl->value) {
			const u16 vblank = MT9T031_VERTICAL_BLANK;
			const u32 shutter_max = MT9T031_MAX_HEIGHT + vblank;
			if (set_shutter(client, icd->height +
					icd->y_skip_top + vblank) < 0)
				return -EIO;
			qctrl = soc_camera_find_qctrl(icd->ops, V4L2_CID_EXPOSURE);
			icd->exposure = (shutter_max / 2 + (icd->height +
					 icd->y_skip_top + vblank - 1) *
					 (qctrl->maximum - qctrl->minimum)) /
				shutter_max + qctrl->minimum;
			mt9t031->autoexposure = 1;
		} else
			mt9t031->autoexposure = 0;
		break;
	}
	return 0;
}

/* Interface active, can use i2c. If it fails, it can indeed mean, that
 * this wasn't our capture interface, so, we wait for the right one */
static int mt9t031_video_probe(struct soc_camera_device *icd,
			       struct i2c_client *client)
{
	struct mt9t031 *mt9t031 = i2c_get_clientdata(client);
	s32 data;
	int ret;

	/* We must have a parent by now. And it cannot be a wrong one.
	 * So this entire test is completely redundant. */
	if (!icd->dev.parent ||
	    to_soc_camera_host(icd->dev.parent)->nr != icd->iface)
		return -ENODEV;

	/* Switch master clock on */
	ret = soc_camera_video_start(icd, &client->dev);
	if (ret)
		return ret;

	/* Enable the chip */
	data = reg_write(client, MT9T031_CHIP_ENABLE, 1);
	dev_dbg(&icd->dev, "write: %d\n", data);

	/* Read out the chip version register */
	data = reg_read(client, MT9T031_CHIP_VERSION);

	soc_camera_video_stop(icd);

	switch (data) {
	case 0x1621:
		mt9t031->model = V4L2_IDENT_MT9T031;
		icd->formats = mt9t031_colour_formats;
		icd->num_formats = ARRAY_SIZE(mt9t031_colour_formats);
		break;
	default:
		dev_err(&icd->dev,
			"No MT9T031 chip detected, register read %x\n", data);
		return -ENODEV;
	}

	dev_info(&icd->dev, "Detected a MT9T031 chip ID %x\n", data);

	return 0;
}

static int mt9t031_probe(struct i2c_client *client,
			 const struct i2c_device_id *did)
{
	struct mt9t031 *mt9t031;
	struct soc_camera_device *icd = client->dev.platform_data;
	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
	struct soc_camera_link *icl;
	int ret;

	if (!icd) {
		dev_err(&client->dev, "MT9T031: missing soc-camera data!\n");
		return -EINVAL;
	}

	icl = to_soc_camera_link(icd);
	if (!icl) {
		dev_err(&client->dev, "MT9T031 driver needs platform data\n");
		return -EINVAL;
	}

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA)) {
		dev_warn(&adapter->dev,
			 "I2C-Adapter doesn't support I2C_FUNC_SMBUS_WORD\n");
		return -EIO;
	}

	mt9t031 = kzalloc(sizeof(struct mt9t031), GFP_KERNEL);
	if (!mt9t031)
		return -ENOMEM;

	i2c_set_clientdata(client, mt9t031);

	/* Second stage probe - when a capture adapter is there */
	icd->ops	= &mt9t031_ops;
	icd->x_min	= MT9T031_COLUMN_SKIP;
	icd->y_min	= MT9T031_ROW_SKIP;
	icd->x_current	= icd->x_min;
	icd->y_current	= icd->y_min;
	icd->width_min	= MT9T031_MIN_WIDTH;
	icd->width_max	= MT9T031_MAX_WIDTH;
	icd->height_min	= MT9T031_MIN_HEIGHT;
	icd->height_max	= MT9T031_MAX_HEIGHT;
	icd->y_skip_top	= 0;
	/* Simulated autoexposure. If enabled, we calculate shutter width
	 * ourselves in the driver based on vertical blanking and frame width */
	mt9t031->autoexposure = 1;

	mt9t031->xskip = 1;
	mt9t031->yskip = 1;

	ret = mt9t031_video_probe(icd, client);
	if (ret) {
		icd->ops = NULL;
		i2c_set_clientdata(client, NULL);
		kfree(mt9t031);
	}

	return ret;
}

static int mt9t031_remove(struct i2c_client *client)
{
	struct mt9t031 *mt9t031 = i2c_get_clientdata(client);
	struct soc_camera_device *icd = client->dev.platform_data;

	icd->ops = NULL;
	i2c_set_clientdata(client, NULL);
	client->driver = NULL;
	kfree(mt9t031);

	return 0;
}

static const struct i2c_device_id mt9t031_id[] = {
	{ "mt9t031", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, mt9t031_id);

static struct i2c_driver mt9t031_i2c_driver = {
	.driver = {
		.name = "mt9t031",
	},
	.probe		= mt9t031_probe,
	.remove		= mt9t031_remove,
	.id_table	= mt9t031_id,
};

static int __init mt9t031_mod_init(void)
{
	return i2c_add_driver(&mt9t031_i2c_driver);
}

static void __exit mt9t031_mod_exit(void)
{
	i2c_del_driver(&mt9t031_i2c_driver);
}

module_init(mt9t031_mod_init);
module_exit(mt9t031_mod_exit);

MODULE_DESCRIPTION("Micron MT9T031 Camera driver");
MODULE_AUTHOR("Guennadi Liakhovetski <lg@denx.de>");
MODULE_LICENSE("GPL v2");