V4L/DVB (4798): OmniVision OV7670 driver

This patch adds a V4L2 driver for the OmniVision OV7670 camera.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 1002 insertions, 0 deletions

diff --git a/drivers/media/video/ov7670.c b/drivers/media/video/ov7670.c
new file mode 100644
index 000000000000..382aa83b73c5
--- /dev/null
+++ b/drivers/media/video/ov7670.c
@@ -0,0 +1,1002 @@
+/*
+ * A V4L2 driver for OmniVision OV7670 cameras.
+ *
+ * Copyright 2006 One Laptop Per Child Association, Inc.  Written
+ * by Jonathan Corbet with substantial inspiration from Mark
+ * McClelland's ovcamchip code.
+ *
+ * This file may be distributed under the terms of the GNU General
+ * Public License, version 2.
+ */
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/videodev.h>
+#include <media/v4l2-common.h>
+#include <linux/i2c.h>
+
+
+MODULE_AUTHOR("Jonathan Corbet <corbet@lwn.net.");
+MODULE_DESCRIPTION("A low-level driver for OmniVision ov7670 sensors");
+MODULE_LICENSE("GPL");
+
+/*
+ * Basic window sizes.  These probably belong somewhere more globally
+ * useful.
+ */
+#define VGA_WIDTH	640
+#define VGA_HEIGHT	480
+#define QVGA_WIDTH	320
+#define QVGA_HEIGHT	240
+#define CIF_WIDTH	352
+#define CIF_HEIGHT	288
+#define QCIF_WIDTH	176
+#define	QCIF_HEIGHT	144
+
+/*
+ * The 7670 sits on i2c with ID 0x42
+ */
+#define OV7670_I2C_ADDR 0x42
+
+/* Registers */
+#define REG_GAIN	0x00	/* Gain lower 8 bits (rest in vref) */
+#define REG_BLUE	0x01	/* blue gain */
+#define REG_RED		0x02	/* red gain */
+#define REG_VREF	0x03	/* Pieces of GAIN, VSTART, VSTOP */
+#define REG_COM1	0x04	/* Control 1 */
+#define  COM1_CCIR656	  0x40  /* CCIR656 enable */
+#define REG_BAVE	0x05	/* U/B Average level */
+#define REG_GbAVE	0x06	/* Y/Gb Average level */
+#define REG_AECHH	0x07	/* AEC MS 5 bits */
+#define REG_RAVE	0x08	/* V/R Average level */
+#define REG_COM2	0x09	/* Control 2 */
+#define  COM2_SSLEEP	  0x10	/* Soft sleep mode */
+#define REG_PID		0x0a	/* Product ID MSB */
+#define REG_VER		0x0b	/* Product ID LSB */
+#define REG_COM3	0x0c	/* Control 3 */
+#define  COM3_SWAP	  0x40	  /* Byte swap */
+#define  COM3_SCALEEN	  0x08	  /* Enable scaling */
+#define  COM3_DCWEN	  0x04	  /* Enable downsamp/crop/window */
+#define REG_COM4	0x0d	/* Control 4 */
+#define REG_COM5	0x0e	/* All "reserved" */
+#define REG_COM6	0x0f	/* Control 6 */
+#define REG_AECH	0x10	/* More bits of AEC value */
+#define REG_CLKRC	0x11	/* Clocl control */
+#define   CLK_EXT	  0x40	  /* Use external clock directly */
+#define   CLK_SCALE	  0x3f	  /* Mask for internal clock scale */
+#define REG_COM7	0x12	/* Control 7 */
+#define   COM7_RESET	  0x80	  /* Register reset */
+#define   COM7_FMT_MASK	  0x38
+#define   COM7_FMT_VGA	  0x00
+#define	  COM7_FMT_CIF	  0x20	  /* CIF format */
+#define   COM7_FMT_QVGA	  0x10	  /* QVGA format */
+#define   COM7_FMT_QCIF	  0x08	  /* QCIF format */
+#define	  COM7_RGB	  0x04	  /* bits 0 and 2 - RGB format */
+#define	  COM7_YUV	  0x00	  /* YUV */
+#define	  COM7_BAYER	  0x01	  /* Bayer format */
+#define	  COM7_PBAYER	  0x05	  /* "Processed bayer" */
+#define REG_COM8	0x13	/* Control 8 */
+#define   COM8_FASTAEC	  0x80	  /* Enable fast AGC/AEC */
+#define   COM8_AECSTEP	  0x40	  /* Unlimited AEC step size */
+#define   COM8_BFILT	  0x20	  /* Band filter enable */
+#define   COM8_AGC	  0x04	  /* Auto gain enable */
+#define   COM8_AWB	  0x02	  /* White balance enable */
+#define   COM8_AEC	  0x01	  /* Auto exposure enable */
+#define REG_COM9	0x14	/* Control 9  - gain ceiling */
+#define REG_COM10	0x15	/* Control 10 */
+#define   COM10_HSYNC	  0x40	  /* HSYNC instead of HREF */
+#define   COM10_PCLK_HB	  0x20	  /* Suppress PCLK on horiz blank */
+#define   COM10_HREF_REV  0x08	  /* Reverse HREF */
+#define   COM10_VS_LEAD	  0x04	  /* VSYNC on clock leading edge */
+#define   COM10_VS_NEG	  0x02	  /* VSYNC negative */
+#define   COM10_HS_NEG	  0x01	  /* HSYNC negative */
+#define REG_HSTART	0x17	/* Horiz start high bits */
+#define REG_HSTOP	0x18	/* Horiz stop high bits */
+#define REG_VSTART	0x19	/* Vert start high bits */
+#define REG_VSTOP	0x1a	/* Vert stop high bits */
+#define REG_PSHFT	0x1b	/* Pixel delay after HREF */
+#define REG_MIDH	0x1c	/* Manuf. ID high */
+#define REG_MIDL	0x1d	/* Manuf. ID low */
+#define REG_MVFP	0x1e	/* Mirror / vflip */
+#define   MVFP_MIRROR	  0x20	  /* Mirror image */
+#define   MVFP_FLIP	  0x10	  /* Vertical flip */
+
+#define REG_AEW		0x24	/* AGC upper limit */
+#define REG_AEB		0x25	/* AGC lower limit */
+#define REG_VPT		0x26	/* AGC/AEC fast mode op region */
+#define REG_HSYST	0x30	/* HSYNC rising edge delay */
+#define REG_HSYEN	0x31	/* HSYNC falling edge delay */
+#define REG_HREF	0x32	/* HREF pieces */
+#define REG_TSLB	0x3a	/* lots of stuff */
+#define   TSLB_YLAST	  0x04	  /* UYVY or VYUY - see com13 */
+#define REG_COM11	0x3b	/* Control 11 */
+#define   COM11_NIGHT	  0x80	  /* NIght mode enable */
+#define   COM11_NMFR	  0x60	  /* Two bit NM frame rate */
+#define   COM11_HZAUTO	  0x10	  /* Auto detect 50/60 Hz */
+#define	  COM11_50HZ	  0x08	  /* Manual 50Hz select */
+#define   COM11_EXP	  0x02
+#define REG_COM12	0x3c	/* Control 12 */
+#define   COM12_HREF	  0x80	  /* HREF always */
+#define REG_COM13	0x3d	/* Control 13 */
+#define   COM13_GAMMA	  0x80	  /* Gamma enable */
+#define	  COM13_UVSAT	  0x40	  /* UV saturation auto adjustment */
+#define   COM13_UVSWAP	  0x01	  /* V before U - w/TSLB */
+#define REG_COM14	0x3e	/* Control 14 */
+#define   COM14_DCWEN	  0x10	  /* DCW/PCLK-scale enable */
+#define REG_EDGE	0x3f	/* Edge enhancement factor */
+#define REG_COM15	0x40	/* Control 15 */
+#define   COM15_R10F0	  0x00	  /* Data range 10 to F0 */
+#define	  COM15_R01FE	  0x80	  /*            01 to FE */
+#define   COM15_R00FF	  0xc0	  /*            00 to FF */
+#define   COM15_RGB565	  0x10	  /* RGB565 output */
+#define   COM15_RGB555	  0x30	  /* RGB555 output */
+#define REG_COM16	0x41	/* Control 16 */
+#define   COM16_AWBGAIN   0x08	  /* AWB gain enable */
+#define REG_COM17	0x42	/* Control 17 */
+#define   COM17_AECWIN	  0xc0	  /* AEC window - must match COM4 */
+#define   COM17_CBAR	  0x08	  /* DSP Color bar */
+
+#define REG_BRIGHT	0x55	/* Brightness */
+#define REG_CONTRAS	0x56	/* Contrast control */
+
+#define REG_GFIX	0x69	/* Fix gain control */
+
+#define REG_RGB444	0x8c	/* RGB 444 control */
+#define   R444_ENABLE	  0x02	  /* Turn on RGB444, overrides 5x5 */
+#define   R444_RGBX	  0x01	  /* Empty nibble at end */
+
+#define REG_HAECC1	0x9f	/* Hist AEC/AGC control 1 */
+#define REG_HAECC2	0xa0	/* Hist AEC/AGC control 2 */
+
+#define REG_BD50MAX	0xa5	/* 50hz banding step limit */
+#define REG_HAECC3	0xa6	/* Hist AEC/AGC control 3 */
+#define REG_HAECC4	0xa7	/* Hist AEC/AGC control 4 */
+#define REG_HAECC5	0xa8	/* Hist AEC/AGC control 5 */
+#define REG_HAECC6	0xa9	/* Hist AEC/AGC control 6 */
+#define REG_HAECC7	0xaa	/* Hist AEC/AGC control 7 */
+#define REG_BD60MAX	0xab	/* 60hz banding step limit */
+
+
+/*
+ * The default register settings, as obtained from OmniVision.  There
+ * is really no making sense of most of these - lots of "reserved" values
+ * and such.
+ *
+ * These settings give VGA YUYV.
+ */
+
+struct regval_list {
+	unsigned char reg_num;
+	unsigned char value;
+};
+
+static struct regval_list ov7670_default_regs[] = {
+	{ REG_COM7, COM7_RESET },
+/*
+ * Clock scale: 3 = 15fps
+ *              2 = 20fps
+ *              1 = 30fps
+ */
+	{ REG_CLKRC, 0x1 },	/* OV: clock scale (15 fps) */
+	{ REG_TSLB,  0x04 },	/* OV */
+	{ REG_COM7, 0 },	/* VGA */
+	/*
+	 * Set the hardware window.  These values from OV don't entirely
+	 * make sense - hstop is less than hstart.  But they work...
+	 */
+	{ REG_HSTART, 0x13 },	{ REG_HSTOP, 0x01 },
+	{ REG_HREF, 0xb6 },	{ REG_VSTART, 0x02 },
+	{ REG_VSTOP, 0x7a },	{ REG_VREF, 0x0a },
+
+	{ REG_COM3, 0 },	{ REG_COM14, 0 },
+	/* Mystery scaling numbers */
+	{ 0x70, 0x3a },		{ 0x71, 0x35 },
+	{ 0x72, 0x11 },		{ 0x73, 0xf0 },
+	{ 0xa2, 0x02 },		{ REG_COM10, 0x0 },
+
+	/* Gamma curve values */
+	{ 0x7a, 0x20 },		{ 0x7b, 0x10 },
+	{ 0x7c, 0x1e },		{ 0x7d, 0x35 },
+	{ 0x7e, 0x5a },		{ 0x7f, 0x69 },
+	{ 0x80, 0x76 },		{ 0x81, 0x80 },
+	{ 0x82, 0x88 },		{ 0x83, 0x8f },
+	{ 0x84, 0x96 },		{ 0x85, 0xa3 },
+	{ 0x86, 0xaf },		{ 0x87, 0xc4 },
+	{ 0x88, 0xd7 },		{ 0x89, 0xe8 },
+
+	/* AGC and AEC parameters.  Note we start by disabling those features,
+	   then turn them only after tweaking the values. */
+	{ REG_COM8, COM8_FASTAEC | COM8_AECSTEP | COM8_BFILT },
+	{ REG_GAIN, 0 },	{ REG_AECH, 0 },
+	{ REG_COM4, 0x40 }, /* magic reserved bit */
+	{ REG_COM9, 0x18 }, /* 4x gain + magic rsvd bit */
+	{ REG_BD50MAX, 0x05 },	{ REG_BD60MAX, 0x07 },
+	{ REG_AEW, 0x95 },	{ REG_AEB, 0x33 },
+	{ REG_VPT, 0xe3 },	{ REG_HAECC1, 0x78 },
+	{ REG_HAECC2, 0x68 },	{ 0xa1, 0x03 }, /* magic */
+	{ REG_HAECC3, 0xd8 },	{ REG_HAECC4, 0xd8 },
+	{ REG_HAECC5, 0xf0 },	{ REG_HAECC6, 0x90 },
+	{ REG_HAECC7, 0x94 },
+	{ REG_COM8, COM8_FASTAEC|COM8_AECSTEP|COM8_BFILT|COM8_AGC|COM8_AEC },
+
+	/* Almost all of these are magic "reserved" values.  */
+	{ REG_COM5, 0x61 },	{ REG_COM6, 0x4b },
+	{ 0x16, 0x02 },		{ REG_MVFP, 0x07|MVFP_MIRROR },
+	{ 0x21, 0x02 },		{ 0x22, 0x91 },
+	{ 0x29, 0x07 },		{ 0x33, 0x0b },
+	{ 0x35, 0x0b },		{ 0x37, 0x1d },
+	{ 0x38, 0x71 },		{ 0x39, 0x2a },
+	{ REG_COM12, 0x78 },	{ 0x4d, 0x40 },
+	{ 0x4e, 0x20 },		{ REG_GFIX, 0 },
+	{ 0x6b, 0x4a },		{ 0x74, 0x10 },
+	{ 0x8d, 0x4f },		{ 0x8e, 0 },
+	{ 0x8f, 0 },		{ 0x90, 0 },
+	{ 0x91, 0 },		{ 0x96, 0 },
+	{ 0x9a, 0 },		{ 0xb0, 0x84 },
+	{ 0xb1, 0x0c },		{ 0xb2, 0x0e },
+	{ 0xb3, 0x82 },		{ 0xb8, 0x0a },
+
+	/* More reserved magic, some of which tweaks white balance */
+	{ 0x43, 0x0a },		{ 0x44, 0xf0 },
+	{ 0x45, 0x34 },		{ 0x46, 0x58 },
+	{ 0x47, 0x28 },		{ 0x48, 0x3a },
+	{ 0x59, 0x88 },		{ 0x5a, 0x88 },
+	{ 0x5b, 0x44 },		{ 0x5c, 0x67 },
+	{ 0x5d, 0x49 },		{ 0x5e, 0x0e },
+	{ 0x6c, 0x0a },		{ 0x6d, 0x55 },
+	{ 0x6e, 0x11 },		{ 0x6f, 0x9f }, /* "9e for advance AWB" */
+	{ 0x6a, 0x40 },		{ REG_BLUE, 0x40 },
+	{ REG_RED, 0x60 },
+	{ REG_COM8, COM8_FASTAEC|COM8_AECSTEP|COM8_BFILT|COM8_AGC|COM8_AEC|COM8_AWB },
+
+	/* Matrix coefficients */
+	{ 0x4f, 0x80 },		{ 0x50, 0x80 },
+	{ 0x51, 0 },		{ 0x52, 0x22 },
+	{ 0x53, 0x5e },		{ 0x54, 0x80 },
+	{ 0x58, 0x9e },
+
+	{ REG_COM16, COM16_AWBGAIN },	{ REG_EDGE, 0 },
+	{ 0x75, 0x05 },		{ 0x76, 0xe1 },
+	{ 0x4c, 0 },		{ 0x77, 0x01 },
+	{ REG_COM13, 0xc3 },	{ 0x4b, 0x09 },
+	{ 0xc9, 0x60 },		{ REG_COM16, 0x38 },
+	{ 0x56, 0x40 },
+
+	{ 0x34, 0x11 },		{ REG_COM11, COM11_EXP },
+	{ 0xa4, 0x88 },		{ 0x96, 0 },
+	{ 0x97, 0x30 },		{ 0x98, 0x20 },
+	{ 0x99, 0x30 },		{ 0x9a, 0x84 },
+	{ 0x9b, 0x29 },		{ 0x9c, 0x03 },
+	{ 0x9d, 0x4c },		{ 0x9e, 0x3f },
+	{ 0x78, 0x04 },
+
+	/* Extra-weird stuff.  Some sort of multiplexor register */
+	{ 0x79, 0x01 },		{ 0xc8, 0xf0 },
+	{ 0x79, 0x0f },		{ 0xc8, 0x00 },
+	{ 0x79, 0x10 },		{ 0xc8, 0x7e },
+	{ 0x79, 0x0a },		{ 0xc8, 0x80 },
+	{ 0x79, 0x0b },		{ 0xc8, 0x01 },
+	{ 0x79, 0x0c },		{ 0xc8, 0x0f },
+	{ 0x79, 0x0d },		{ 0xc8, 0x20 },
+	{ 0x79, 0x09 },		{ 0xc8, 0x80 },
+	{ 0x79, 0x02 },		{ 0xc8, 0xc0 },
+	{ 0x79, 0x03 },		{ 0xc8, 0x40 },
+	{ 0x79, 0x05 },		{ 0xc8, 0x30 },
+	{ 0x79, 0x26 },
+
+	/* Not sure if these should be here */
+	{ 0xf1, 0x10 },		{ 0x0f, 0x1d },
+	{ 0x0f, 0x1f },
+
+	{ 0xff, 0xff },	/* END MARKER */
+};
+
+
+/*
+ * Here we'll try to encapsulate the changes for just the output
+ * video format.
+ *
+ * RGB656 and YUV422 come from OV; RGB444 is homebrewed.
+ *
+ * IMPORTANT RULE: the first entry must be for COM7, see ov7670_s_fmt for why.
+ */
+
+
+static struct regval_list ov7670_fmt_yuv422[] = {
+	{ REG_COM7, 0x0 },  /* Selects YUV mode */
+	{ REG_RGB444, 0 },	/* No RGB444 please */
+	{ REG_COM1, 0 },
+	{ REG_COM15, COM15_R00FF },
+	{ REG_COM9, 0x18 }, /* 4x gain ceiling; 0x8 is reserved bit */
+	{ 0x4f, 0x80 }, 	/* "matrix coefficient 1" */
+	{ 0x50, 0x80 }, 	/* "matrix coefficient 2" */
+	{ 0x52, 0x22 }, 	/* "matrix coefficient 4" */
+	{ 0x53, 0x5e }, 	/* "matrix coefficient 5" */
+	{ 0x54, 0x80 }, 	/* "matrix coefficient 6" */
+	{ REG_COM13, COM13_GAMMA|COM13_UVSAT },
+	{ 0xff, 0xff },
+};
+
+static struct regval_list ov7670_fmt_rgb565[] = {
+	{ REG_COM7, COM7_RGB },	/* Selects RGB mode */
+	{ REG_RGB444, 0 },	/* No RGB444 please */
+	{ REG_COM1, 0x0 },
+	{ REG_COM15, COM15_RGB565 },
+	{ REG_COM9, 0x38 }, 	/* 16x gain ceiling; 0x8 is reserved bit */
+	{ 0x4f, 0xb3 }, 	/* "matrix coefficient 1" */
+	{ 0x50, 0xb3 }, 	/* "matrix coefficient 2" */
+	{ 0x52, 0x3d }, 	/* "matrix coefficient 4" */
+	{ 0x53, 0xa7 }, 	/* "matrix coefficient 5" */
+	{ 0x54, 0xe4 }, 	/* "matrix coefficient 6" */
+	{ REG_COM13, COM13_GAMMA|COM13_UVSAT },
+	{ 0xff, 0xff },
+};
+
+static struct regval_list ov7670_fmt_rgb444[] = {
+	{ REG_COM7, COM7_RGB },	/* Selects RGB mode */
+	{ REG_RGB444, R444_ENABLE },	/* Enable xxxxrrrr ggggbbbb */
+	{ REG_COM1, 0x40 },	/* Magic reserved bit */
+	{ REG_COM15, COM15_R01FE|COM15_RGB565 }, /* Data range needed? */
+	{ REG_COM9, 0x38 }, 	/* 16x gain ceiling; 0x8 is reserved bit */
+	{ 0x4f, 0xb3 }, 	/* "matrix coefficient 1" */
+	{ 0x50, 0xb3 }, 	/* "matrix coefficient 2" */
+	{ 0x52, 0x3d }, 	/* "matrix coefficient 4" */
+	{ 0x53, 0xa7 }, 	/* "matrix coefficient 5" */
+	{ 0x54, 0xe4 }, 	/* "matrix coefficient 6" */
+	{ REG_COM13, COM13_GAMMA|COM13_UVSAT|0x2 },  /* Magic rsvd bit */
+	{ 0xff, 0xff },
+};
+
+
+
+
+/*
+ * Low-level register I/O.
+ */
+
+static int ov7670_read(struct i2c_client *c, unsigned char reg,
+		unsigned char *value)
+{
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(c, reg);
+	if (ret > 0)
+		*value = (unsigned char) ret;
+	return ret;
+}
+
+
+static int ov7670_write(struct i2c_client *c, unsigned char reg,
+		unsigned char value)
+{
+	return i2c_smbus_write_byte_data(c, reg, value);
+}
+
+
+/*
+ * Write a list of register settings; ff/ff stops the process.
+ */
+static int ov7670_write_array(struct i2c_client *c, struct regval_list *vals)
+{
+	while (vals->reg_num != 0xff || vals->value != 0xff) {
+		int ret = ov7670_write(c, vals->reg_num, vals->value);
+		if (ret < 0)
+			return ret;
+		vals++;
+	}
+	return 0;
+}
+
+
+/*
+ * Stuff that knows about the sensor.
+ */
+static void ov7670_reset(struct i2c_client *client)
+{
+	ov7670_write(client, REG_COM7, COM7_RESET);
+	msleep(1);
+}
+
+
+static int ov7670_init(struct i2c_client *client)
+{
+	return ov7670_write_array(client, ov7670_default_regs);
+}
+
+
+
+static int ov7670_detect(struct i2c_client *client)
+{
+	unsigned char v;
+	int ret;
+
+	ret = ov7670_init(client);
+	if (ret < 0)
+		return ret;
+	ret = ov7670_read(client, REG_MIDH, &v);
+	if (ret < 0)
+		return ret;
+	if (v != 0x7f) /* OV manuf. id. */
+		return -ENODEV;
+	ret = ov7670_read(client, REG_MIDL, &v);
+	if (ret < 0)
+		return ret;
+	if (v != 0xa2)
+		return -ENODEV;
+	/*
+	 * OK, we know we have an OmniVision chip...but which one?
+	 */
+	ret = ov7670_read(client, REG_PID, &v);
+	if (ret < 0)
+		return ret;
+	if (v != 0x76)  /* PID + VER = 0x76 / 0x73 */
+		return -ENODEV;
+	ret = ov7670_read(client, REG_VER, &v);
+	if (ret < 0)
+		return ret;
+	if (v != 0x73)  /* PID + VER = 0x76 / 0x73 */
+		return -ENODEV;
+	return 0;
+}
+
+
+
+
+
+static struct ov7670_format_struct {
+	__u8 *desc;
+	__u32 pixelformat;
+	struct regval_list *regs;
+} ov7670_formats[] = {
+	{
+		.desc		= "YUYV 4:2:2",
+		.pixelformat	= V4L2_PIX_FMT_YUYV,
+		.regs 		= ov7670_fmt_yuv422,
+	},
+	{
+		.desc		= "RGB 444",
+		.pixelformat	= V4L2_PIX_FMT_RGB444,
+		.regs		= ov7670_fmt_rgb444,
+	},
+	{
+		.desc		= "RGB 565",
+		.pixelformat	= V4L2_PIX_FMT_RGB565,
+		.regs		= ov7670_fmt_rgb565,
+	},
+	/*
+	 * Pretend we do RGB32.  This is here on the assumption that the
+	 * upper layer will reformat RGB444 appropriately.
+	 *
+	 * The entire purpose for this thing's existence is to enable easy
+	 * display of RGB444 for debugging purposes.  It will come out soon.
+	 */
+	{
+		.desc		= "RGB32 (faked)",
+		.pixelformat	= V4L2_PIX_FMT_RGB32,
+		.regs		= ov7670_fmt_rgb444,
+	},
+};
+#define N_OV7670_FMTS (sizeof(ov7670_formats)/sizeof(ov7670_formats[0]))
+
+/*
+ * All formats we support are 2 bytes/pixel.
+ */
+#define BYTES_PER_PIXEL 2
+
+/*
+ * Then there is the issue of window sizes.  Try to capture the info here.
+ */
+static struct ov7670_win_size {
+	int	width;
+	int	height;
+	unsigned char com7_bit;
+	int	hstart;		/* Start/stop values for the camera.  Note */
+	int	hstop;		/* that they do not always make complete */
+	int	vstart;		/* sense to humans, but evidently the sensor */
+	int	vstop;		/* will do the right thing... */
+/* h/vref stuff */
+} ov7670_win_sizes[] = {
+	/* VGA */
+	{
+		.width		= VGA_WIDTH,
+		.height		= VGA_HEIGHT,
+		.com7_bit	= COM7_FMT_VGA,
+		.hstart		= 158,		/* These values from */
+		.hstop		=  14,		/* Omnivision */
+		.vstart		=  10,
+		.vstop		= 490,
+	},
+	/* CIF */
+	{
+		.width		= CIF_WIDTH,
+		.height		= CIF_HEIGHT,
+		.com7_bit	= COM7_FMT_CIF,
+		.hstart		= 170,		/* Empirically determined */
+		.hstop		=  90,
+		.vstart		=  14,
+		.vstop		= 494,
+	},
+	/* QVGA */
+	{
+		.width		= QVGA_WIDTH,
+		.height		= QVGA_HEIGHT,
+		.com7_bit	= COM7_FMT_QVGA,
+		.hstart		= 164,		/* Empirically determined */
+		.hstop		=  20,
+		.vstart		=  14,
+		.vstop		= 494,
+	},
+};
+
+#define N_WIN_SIZES (sizeof(ov7670_win_sizes)/sizeof(ov7670_win_sizes[0]))
+
+
+/*
+ * Store a set of start/stop values into the camera.
+ */
+static int ov7670_set_hw(struct i2c_client *client, int hstart, int hstop,
+		int vstart, int vstop)
+{
+	int ret;
+	unsigned char v;
+/*
+ * Horizontal: 11 bits, top 8 live in hstart and hstop.  Bottom 3 of
+ * hstart are in href[2:0], bottom 3 of hstop in href[5:3].  There is
+ * a mystery "edge offset" value in the top two bits of href.
+ */
+	ret =  ov7670_write(client, REG_HSTART, (hstart >> 3) & 0xff);
+	ret += ov7670_write(client, REG_HSTOP, (hstop >> 3) & 0xff);
+	ret += ov7670_read(client, REG_HREF, &v);
+	v = (v & 0xc0) | ((hstop & 0x7) << 3) | (hstart & 0x7);
+	msleep(10);
+	ret += ov7670_write(client, REG_HREF, v);
+/*
+ * Vertical: similar arrangement, but only 10 bits.
+ */
+	ret += ov7670_write(client, REG_VSTART, (vstart >> 2) & 0xff);
+	ret += ov7670_write(client, REG_VSTOP, (vstop >> 2) & 0xff);
+	ret += ov7670_read(client, REG_VREF, &v);
+	v = (v & 0xf0) | ((vstop & 0x3) << 2) | (vstart & 0x3);
+	msleep(10);
+	ret += ov7670_write(client, REG_VREF, v);
+	return ret;
+}
+
+
+static int ov7670_enum_fmt(struct i2c_client *c, struct v4l2_fmtdesc *fmt)
+{
+	struct ov7670_format_struct *ofmt;
+
+	if (fmt->index >= N_OV7670_FMTS)
+		return -EINVAL;
+
+	ofmt = ov7670_formats + fmt->index;
+	fmt->flags = 0;
+	strcpy(fmt->description, ofmt->desc);
+	fmt->pixelformat = ofmt->pixelformat;
+	return 0;
+}
+
+
+static int ov7670_try_fmt(struct i2c_client *c, struct v4l2_format *fmt,
+		struct ov7670_format_struct **ret_fmt,
+		struct ov7670_win_size **ret_wsize)
+{
+	int index;
+	struct ov7670_win_size *wsize;
+	struct v4l2_pix_format *pix = &fmt->fmt.pix;
+
+	for (index = 0; index < N_OV7670_FMTS; index++)
+		if (ov7670_formats[index].pixelformat == pix->pixelformat)
+			break;
+	if (index >= N_OV7670_FMTS)
+		return -EINVAL;
+	if (ret_fmt != NULL)
+		*ret_fmt = ov7670_formats + index;
+	/*
+	 * Fields: the OV devices claim to be progressive.
+	 */
+	if (pix->field == V4L2_FIELD_ANY)
+		pix->field = V4L2_FIELD_NONE;
+	else if (pix->field != V4L2_FIELD_NONE)
+		return -EINVAL;
+	/*
+	 * Round requested image size down to the nearest
+	 * we support, but not below the smallest.
+	 */
+	for (wsize = ov7670_win_sizes; wsize < ov7670_win_sizes + N_WIN_SIZES;
+	     wsize++)
+		if (pix->width >= wsize->width && pix->height >= wsize->height)
+			break;
+	if (wsize > ov7670_win_sizes + N_WIN_SIZES)
+		wsize--;   /* Take the smallest one */
+	if (ret_wsize != NULL)
+		*ret_wsize = wsize;
+	/*
+	 * Note the size we'll actually handle.
+	 */
+	pix->width = wsize->width;
+	pix->height = wsize->height;
+	pix->bytesperline = pix->width*BYTES_PER_PIXEL;
+	if (pix->pixelformat == V4L2_PIX_FMT_RGB32)
+		pix->bytesperline *= 2;
+	pix->sizeimage = pix->height*pix->bytesperline;
+	return 0;
+
+}
+
+/*
+ * Set a format.
+ */
+static int ov7670_s_fmt(struct i2c_client *c, struct v4l2_format *fmt)
+{
+	int ret;
+	struct ov7670_format_struct *ovfmt;
+	struct ov7670_win_size *wsize;
+	unsigned char com7;
+
+	ret = ov7670_try_fmt(c, fmt, &ovfmt, &wsize);
+	if (ret)
+		return ret;
+	/*
+	 * COM7 is a pain in the ass, it doesn't like to be read then
+	 * quickly written afterward.  But we have everything we need
+	 * to set it absolutely here, as long as the format-specific
+	 * register sets list it first.
+	 */
+	com7 = ovfmt->regs[0].value;
+	com7 |= wsize->com7_bit;
+	ov7670_write(c, REG_COM7, com7);
+	/*
+	 * Now write the rest of the array.  Also store start/stops
+	 */
+	ov7670_write_array(c, ovfmt->regs + 1);
+	ov7670_set_hw(c, wsize->hstart, wsize->hstop, wsize->vstart,
+			wsize->vstop);
+	return 0;
+}
+
+/*
+ * Code for dealing with controls.
+ */
+
+/*
+ * Some weird registers seem to store values in a sign/magnitude format!
+ */
+static unsigned char ov7670_sm_to_abs(unsigned char v)
+{
+	if ((v & 0x80) == 0)
+		return v + 128;
+	else
+		return 128 - (v & 0x7f);
+}
+
+
+static unsigned char ov7670_abs_to_sm(unsigned char v)
+{
+	if (v > 127)
+		return v & 0x7f;
+	else
+		return (128 - v) | 0x80;
+}
+
+static int ov7670_t_brightness(struct i2c_client *client, unsigned char value)
+{
+	unsigned char com8;
+	int ret;
+
+	ov7670_read(client, REG_COM8, &com8);
+	com8 &= ~COM8_AEC;
+	ov7670_write(client, REG_COM8, com8);
+	value = ov7670_abs_to_sm(value);
+	ret = ov7670_write(client, REG_BRIGHT, value);
+	return ret;
+}
+
+static int ov7670_q_brightness(struct i2c_client *client, unsigned char *value)
+{
+	int ret;
+	ret = ov7670_read(client, REG_BRIGHT, value);
+	*value = ov7670_sm_to_abs(*value);
+	return ret;
+}
+
+static int ov7670_t_contrast(struct i2c_client *client, unsigned char value)
+{
+	return ov7670_write(client, REG_CONTRAS, value);
+}
+
+static int ov7670_q_contrast(struct i2c_client *client, unsigned char *value)
+{
+	return ov7670_read(client, REG_CONTRAS, value);
+}
+
+static int ov7670_q_hflip(struct i2c_client *client, unsigned char *value)
+{
+	int ret;
+	unsigned char v;
+
+	ret = ov7670_read(client, REG_MVFP, &v);
+	*value = (v & MVFP_MIRROR) == MVFP_MIRROR;
+	return ret;
+}
+
+
+static int ov7670_t_hflip(struct i2c_client *client, unsigned char value)
+{
+	unsigned char v;
+	int ret;
+
+	ret = ov7670_read(client, REG_MVFP, &v);
+	if (value)
+		v |= MVFP_MIRROR;
+	else
+		v &= ~MVFP_MIRROR;
+	msleep(10);  /* FIXME */
+	ret += ov7670_write(client, REG_MVFP, v);
+	return ret;
+}
+
+
+
+static int ov7670_q_vflip(struct i2c_client *client, unsigned char *value)
+{
+	int ret;
+	unsigned char v;
+
+	ret = ov7670_read(client, REG_MVFP, &v);
+	*value = (v & MVFP_FLIP) == MVFP_FLIP;
+	return ret;
+}
+
+
+static int ov7670_t_vflip(struct i2c_client *client, unsigned char value)
+{
+	unsigned char v;
+	int ret;
+
+	ret = ov7670_read(client, REG_MVFP, &v);
+	if (value)
+		v |= MVFP_FLIP;
+	else
+		v &= ~MVFP_FLIP;
+	msleep(10);  /* FIXME */
+	ret += ov7670_write(client, REG_MVFP, v);
+	return ret;
+}
+
+
+static struct ov7670_control {
+	struct v4l2_queryctrl qc;
+	int (*query)(struct i2c_client *c, unsigned char *value);
+	int (*tweak)(struct i2c_client *c, unsigned char value);
+} ov7670_controls[] =
+{
+	{
+		.qc = {
+			.id = V4L2_CID_BRIGHTNESS,
+			.type = V4L2_CTRL_TYPE_INTEGER,
+			.name = "Brightness",
+			.minimum = 0,
+			.maximum = 255,
+			.step = 1,
+			.default_value = 0x80,
+			.flags = V4L2_CTRL_FLAG_SLIDER
+		},
+		.tweak = ov7670_t_brightness,
+		.query = ov7670_q_brightness,
+	},
+	{
+		.qc = {
+			.id = V4L2_CID_CONTRAST,
+			.type = V4L2_CTRL_TYPE_INTEGER,
+			.name = "Contrast",
+			.minimum = 0,
+			.maximum = 127,
+			.step = 1,
+			.default_value = 0x40,   /* XXX ov7670 spec */
+			.flags = V4L2_CTRL_FLAG_SLIDER
+		},
+		.tweak = ov7670_t_contrast,
+		.query = ov7670_q_contrast,
+	},
+	{
+		.qc = {
+			.id = V4L2_CID_VFLIP,
+			.type = V4L2_CTRL_TYPE_BOOLEAN,
+			.name = "Vertical flip",
+			.minimum = 0,
+			.maximum = 1,
+			.step = 1,
+			.default_value = 0,
+		},
+		.tweak = ov7670_t_vflip,
+		.query = ov7670_q_vflip,
+	},
+	{
+		.qc = {
+			.id = V4L2_CID_HFLIP,
+			.type = V4L2_CTRL_TYPE_BOOLEAN,
+			.name = "Horizontal mirror",
+			.minimum = 0,
+			.maximum = 1,
+			.step = 1,
+			.default_value = 0,
+		},
+		.tweak = ov7670_t_hflip,
+		.query = ov7670_q_hflip,
+	},
+};
+#define N_CONTROLS (sizeof(ov7670_controls)/sizeof(ov7670_controls[0]))
+
+static struct ov7670_control *ov7670_find_control(__u32 id)
+{
+	int i;
+
+	for (i = 0; i < N_CONTROLS; i++)
+		if (ov7670_controls[i].qc.id == id)
+			return ov7670_controls + i;
+	return NULL;
+}
+
+
+static int ov7670_queryctrl(struct i2c_client *client,
+		struct v4l2_queryctrl *qc)
+{
+	struct ov7670_control *ctrl = ov7670_find_control(qc->id);
+
+	if (ctrl == NULL)
+		return -EINVAL;
+	*qc = ctrl->qc;
+	return 0;
+}
+
+static int ov7670_g_ctrl(struct i2c_client *client, struct v4l2_control *ctrl)
+{
+	struct ov7670_control *octrl = ov7670_find_control(ctrl->id);
+	int ret;
+	unsigned char v;
+
+	if (octrl == NULL)
+		return -EINVAL;
+	ret = octrl->query(client, &v);
+	if (ret >= 0) {
+		ctrl->value = v;
+		return 0;
+	}
+	return ret;
+}
+
+static int ov7670_s_ctrl(struct i2c_client *client, struct v4l2_control *ctrl)
+{
+	struct ov7670_control *octrl = ov7670_find_control(ctrl->id);
+
+	if (octrl == NULL)
+		return -EINVAL;
+	return octrl->tweak(client, ctrl->value);
+}
+
+
+
+
+
+
+
+/*
+ * Basic i2c stuff.
+ */
+static struct i2c_driver ov7670_driver;
+
+static int ov7670_attach(struct i2c_adapter *adapter)
+{
+	int ret;
+	struct i2c_client *client;
+
+	printk(KERN_ERR "ov7670 attach, id = %d\n", adapter->id);
+	/*
+	 * For now: only deal with adapters we recognize.
+	 */
+	if (adapter->id != I2C_HW_SMBUS_CAFE)
+		return -ENODEV;
+
+	printk(KERN_ERR "ov7670 accepting\n");
+	client = kzalloc(sizeof (struct i2c_client), GFP_KERNEL);
+	if (! client)
+		return -ENOMEM;
+	client->adapter = adapter;
+	client->addr = OV7670_I2C_ADDR;
+	client->driver = &ov7670_driver,
+	strcpy(client->name, "OV7670");
+	/* Do we need clientdata? */
+
+	/*
+	 * Make sure it's an ov7670
+	 */
+	ret = ov7670_detect(client);
+	printk(KERN_ERR "detect result is %d\n", ret);
+	if (ret)
+		goto out_free;
+	i2c_attach_client(client);
+	return 0;
+
+  out_free:
+	kfree(client);
+	return ret;
+}
+
+
+static int ov7670_detach(struct i2c_client *client)
+{
+	i2c_detach_client(client);
+	kfree(client);
+	return 0;
+}
+
+
+static int ov7670_command(struct i2c_client *client, unsigned int cmd,
+		void *arg)
+{
+	switch (cmd) {
+	case VIDIOC_INT_G_CHIP_IDENT:
+		* (enum v4l2_chip_ident *) arg = V4L2_IDENT_OV7670;
+		return 0;
+
+	case VIDIOC_INT_RESET:
+		ov7670_reset(client);
+		return 0;
+
+	case VIDIOC_INT_INIT:
+		return ov7670_init(client);
+
+	case VIDIOC_ENUM_FMT:
+		return ov7670_enum_fmt(client, (struct v4l2_fmtdesc *) arg);
+	case VIDIOC_TRY_FMT:
+		return ov7670_try_fmt(client, (struct v4l2_format *) arg, NULL, NULL);
+	case VIDIOC_S_FMT:
+		return ov7670_s_fmt(client, (struct v4l2_format *) arg);
+	case VIDIOC_QUERYCTRL:
+		return ov7670_queryctrl(client, (struct v4l2_queryctrl *) arg);
+	case VIDIOC_S_CTRL:
+		return ov7670_s_ctrl(client, (struct v4l2_control *) arg);
+	case VIDIOC_G_CTRL:
+		return ov7670_g_ctrl(client, (struct v4l2_control *) arg);
+	/* Todo:
+	   g/s_parm
+	   initialization
+	*/
+	}
+	return -EINVAL;
+}
+
+
+
+static struct i2c_driver ov7670_driver = {
+	.driver = {
+		.name = "ov7670",
+	},
+	.id 		= I2C_DRIVERID_OV7670,
+	.class 		= I2C_CLASS_CAM_DIGITAL,
+	.attach_adapter = ov7670_attach,
+	.detach_client	= ov7670_detach,
+	.command	= ov7670_command,
+};
+
+
+/*
+ * Module initialization
+ */
+static int __init ov7670_mod_init(void)
+{
+	printk(KERN_NOTICE "OmniVision ov7670 sensor driver, at your service\n");
+	return i2c_add_driver(&ov7670_driver);
+}
+
+static void __exit ov7670_mod_exit(void)
+{
+	i2c_del_driver(&ov7670_driver);
+}
+
+module_init(ov7670_mod_init);
+module_exit(ov7670_mod_exit);