/*
 * 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.
 *
 * Copyright 2006-7 Jonathan Corbet <corbet@lwn.net>
 *
 * 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/slab.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/videodev2.h>
#include <media/v4l2-device.h>
#include <media/v4l2-chip-ident.h>
#include <media/v4l2-mediabus.h>
#include <media/ov7670.h>

MODULE_AUTHOR("Jonathan Corbet <corbet@lwn.net>");
MODULE_DESCRIPTION("A low-level driver for OmniVision ov7670 sensors");
MODULE_LICENSE("GPL");

static bool debug;
module_param(debug, bool, 0644);
MODULE_PARM_DESC(debug, "Debug level (0-1)");

/*
 * 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 */

/*
 * This matrix defines how the colors are generated, must be
 * tweaked to adjust hue and saturation.
 *
 * Order: v-red, v-green, v-blue, u-red, u-green, u-blue
 *
 * They are nine-bit signed quantities, with the sign bit
 * stored in 0x58.  Sign for v-red is bit 0, and up from there.
 */
#define REG_CMATRIX_BASE 0x4f
#define   CMATRIX_LEN 6
#define REG_CMATRIX_SIGN 0x58


#define REG_BRIGHT      0x55    /* Brightness */
#define REG_CONTRAS     0x56    /* Contrast control */

#define REG_GFIX        0x69    /* Fix gain control */

#define REG_REG76       0x76    /* OV's name */
#define   R76_BLKPCOR     0x80    /* Black pixel correction enable */
#define   R76_WHTPCOR     0x40    /* White pixel correction enable */

#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 */


/*
 * Information we maintain about a known sensor.
 */
struct ov7670_format_struct;  /* coming later */
struct ov7670_info {
        struct v4l2_subdev sd;
        struct ov7670_format_struct *fmt;  /* Current format */
        unsigned char sat;              /* Saturation value */
        int hue;                        /* Hue value */
        int min_width;                  /* Filter out smaller sizes */
        int min_height;                 /* Filter out smaller sizes */
        int clock_speed;                /* External clock speed (MHz) */
        u8 clkrc;                       /* Clock divider value */
        bool use_smbus;                 /* Use smbus I/O instead of I2C */
};

static inline struct ov7670_info *to_state(struct v4l2_subdev *sd)
{
        return container_of(sd, struct ov7670_info, sd);
}



/*
 * 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 (30 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 },
        { 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|COM11_HZAUTO },
        { 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 },

        { 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 },        /* CCIR601 */
        { REG_COM15, COM15_R00FF },
        { REG_COM9, 0x18 }, /* 4x gain ceiling; 0x8 is reserved bit */
        { 0x4f, 0x80 },         /* "matrix coefficient 1" */
        { 0x50, 0x80 },         /* "matrix coefficient 2" */
        { 0x51, 0    },         /* vb */
        { 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 },      /* CCIR601 */
        { REG_COM15, COM15_RGB565 },
        { REG_COM9, 0x38 },     /* 16x gain ceiling; 0x8 is reserved bit */
        { 0x4f, 0xb3 },         /* "matrix coefficient 1" */
        { 0x50, 0xb3 },         /* "matrix coefficient 2" */
        { 0x51, 0    },         /* vb */
        { 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, 0x0 },      /* CCIR601 */
        { 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" */
        { 0x51, 0    },         /* vb */
        { 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 },
};

static struct regval_list ov7670_fmt_raw[] = {
        { REG_COM7, COM7_BAYER },
        { REG_COM13, 0x08 }, /* No gamma, magic rsvd bit */
        { REG_COM16, 0x3d }, /* Edge enhancement, denoise */
        { REG_REG76, 0xe1 }, /* Pix correction, magic rsvd */
        { 0xff, 0xff },
};



/*
 * Low-level register I/O.
 *
 * Note that there are two versions of these.  On the XO 1, the
 * i2c controller only does SMBUS, so that's what we use.  The
 * ov7670 is not really an SMBUS device, though, so the communication
 * is not always entirely reliable.
 */
static int ov7670_read_smbus(struct v4l2_subdev *sd, unsigned char reg,
                unsigned char *value)
{
        struct i2c_client *client = v4l2_get_subdevdata(sd);
        int ret;

        ret = i2c_smbus_read_byte_data(client, reg);
        if (ret >= 0) {
                *value = (unsigned char)ret;
                ret = 0;
        }
        return ret;
}


static int ov7670_write_smbus(struct v4l2_subdev *sd, unsigned char reg,
                unsigned char value)
{
        struct i2c_client *client = v4l2_get_subdevdata(sd);
        int ret = i2c_smbus_write_byte_data(client, reg, value);

        if (reg == REG_COM7 && (value & COM7_RESET))
                msleep(5);  /* Wait for reset to run */
        return ret;
}

/*
 * On most platforms, we'd rather do straight i2c I/O.
 */
static int ov7670_read_i2c(struct v4l2_subdev *sd, unsigned char reg,
                unsigned char *value)
{
        struct i2c_client *client = v4l2_get_subdevdata(sd);
        u8 data = reg;
        struct i2c_msg msg;
        int ret;

        /*
         * Send out the register address...
         */
        msg.addr = client->addr;
        msg.flags = 0;
        msg.len = 1;
        msg.buf = &data;
        ret = i2c_transfer(client->adapter, &msg, 1);
        if (ret < 0) {
                printk(KERN_ERR "Error %d on register write\n", ret);
                return ret;
        }
        /*
         * ...then read back the result.
         */
        msg.flags = I2C_M_RD;
        ret = i2c_transfer(client->adapter, &msg, 1);
        if (ret >= 0) {
                *value = data;
                ret = 0;
        }
        return ret;
}


static int ov7670_write_i2c(struct v4l2_subdev *sd, unsigned char reg,
                unsigned char value)
{
        struct i2c_client *client = v4l2_get_subdevdata(sd);
        struct i2c_msg msg;
        unsigned char data[2] = { reg, value };
        int ret;

        msg.addr = client->addr;
        msg.flags = 0;
        msg.len = 2;
        msg.buf = data;
        ret = i2c_transfer(client->adapter, &msg, 1);
        if (ret > 0)
                ret = 0;
        if (reg == REG_COM7 && (value & COM7_RESET))
                msleep(5);  /* Wait for reset to run */
        return ret;
}

static int ov7670_read(struct v4l2_subdev *sd, unsigned char reg,
                unsigned char *value)
{
        struct ov7670_info *info = to_state(sd);
        if (info->use_smbus)
                return ov7670_read_smbus(sd, reg, value);
        else
                return ov7670_read_i2c(sd, reg, value);
}

static int ov7670_write(struct v4l2_subdev *sd, unsigned char reg,
                unsigned char value)
{
        struct ov7670_info *info = to_state(sd);
        if (info->use_smbus)
                return ov7670_write_smbus(sd, reg, value);
        else
                return ov7670_write_i2c(sd, reg, value);
}

/*
 * Write a list of register settings; ff/ff stops the process.
 */
static int ov7670_write_array(struct v4l2_subdev *sd, struct regval_list *vals)
{
        while (vals->reg_num != 0xff || vals->value != 0xff) {
                int ret = ov7670_write(sd, vals->reg_num, vals->value);
                if (ret < 0)
                        return ret;
                vals++;
        }
        return 0;
}


/*
 * Stuff that knows about the sensor.
 */
static int ov7670_reset(struct v4l2_subdev *sd, u32 val)
{
        ov7670_write(sd, REG_COM7, COM7_RESET);
        msleep(1);
        return 0;
}


static int ov7670_init(struct v4l2_subdev *sd, u32 val)
{
        return ov7670_write_array(sd, ov7670_default_regs);
}



static int ov7670_detect(struct v4l2_subdev *sd)
{
        unsigned char v;
        int ret;

        ret = ov7670_init(sd, 0);
        if (ret < 0)
                return ret;
        ret = ov7670_read(sd, REG_MIDH, &v);
        if (ret < 0)
                return ret;
        if (v != 0x7f) /* OV manuf. id. */
                return -ENODEV;
        ret = ov7670_read(sd, 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(sd, REG_PID, &v);
        if (ret < 0)
                return ret;
        if (v != 0x76)  /* PID + VER = 0x76 / 0x73 */
                return -ENODEV;
        ret = ov7670_read(sd, REG_VER, &v);
        if (ret < 0)
                return ret;
        if (v != 0x73)  /* PID + VER = 0x76 / 0x73 */
                return -ENODEV;
        return 0;
}


/*
 * Store information about the video data format.  The color matrix
 * is deeply tied into the format, so keep the relevant values here.
 * The magic matrix numbers come from OmniVision.
 */
static struct ov7670_format_struct {
        enum v4l2_mbus_pixelcode mbus_code;
        enum v4l2_colorspace colorspace;
        struct regval_list *regs;
        int cmatrix[CMATRIX_LEN];
} ov7670_formats[] = {
        {
                .mbus_code      = V4L2_MBUS_FMT_YUYV8_2X8,
                .colorspace     = V4L2_COLORSPACE_JPEG,
                .regs           = ov7670_fmt_yuv422,
                .cmatrix        = { 128, -128, 0, -34, -94, 128 },
        },
        {
                .mbus_code      = V4L2_MBUS_FMT_RGB444_2X8_PADHI_LE,
                .colorspace     = V4L2_COLORSPACE_SRGB,
                .regs           = ov7670_fmt_rgb444,
                .cmatrix        = { 179, -179, 0, -61, -176, 228 },
        },
        {
                .mbus_code      = V4L2_MBUS_FMT_RGB565_2X8_LE,
                .colorspace     = V4L2_COLORSPACE_SRGB,
                .regs           = ov7670_fmt_rgb565,
                .cmatrix        = { 179, -179, 0, -61, -176, 228 },
        },
        {
                .mbus_code      = V4L2_MBUS_FMT_SBGGR8_1X8,
                .colorspace     = V4L2_COLORSPACE_SRGB,
                .regs           = ov7670_fmt_raw,
                .cmatrix        = { 0, 0, 0, 0, 0, 0 },
        },
};
#define N_OV7670_FMTS ARRAY_SIZE(ov7670_formats)


/*
 * Then there is the issue of window sizes.  Try to capture the info here.
 */

/*
 * QCIF mode is done (by OV) in a very strange way - it actually looks like
 * VGA with weird scaling options - they do *not* use the canned QCIF mode
 * which is allegedly provided by the sensor.  So here's the weird register
 * settings.
 */
static struct regval_list ov7670_qcif_regs[] = {
        { REG_COM3, COM3_SCALEEN|COM3_DCWEN },
        { REG_COM3, COM3_DCWEN },
        { REG_COM14, COM14_DCWEN | 0x01},
        { 0x73, 0xf1 },
        { 0xa2, 0x52 },
        { 0x7b, 0x1c },
        { 0x7c, 0x28 },
        { 0x7d, 0x3c },
        { 0x7f, 0x69 },
        { REG_COM9, 0x38 },
        { 0xa1, 0x0b },
        { 0x74, 0x19 },
        { 0x9a, 0x80 },
        { 0x43, 0x14 },
        { REG_COM13, 0xc0 },
        { 0xff, 0xff },
};

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... */
        struct regval_list *regs; /* Regs to tweak */
/* 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,
                .regs           = NULL,
        },
        /* CIF */
        {
                .width          = CIF_WIDTH,
                .height         = CIF_HEIGHT,
                .com7_bit       = COM7_FMT_CIF,
                .hstart         = 170,          /* Empirically determined */
                .hstop          =  90,
                .vstart         =  14,
                .vstop          = 494,
                .regs           = NULL,
        },
        /* QVGA */
        {
                .width          = QVGA_WIDTH,
                .height         = QVGA_HEIGHT,
                .com7_bit       = COM7_FMT_QVGA,
                .hstart         = 168,          /* Empirically determined */
                .hstop          =  24,
                .vstart         =  12,
                .vstop          = 492,
                .regs           = NULL,
        },
        /* QCIF */
        {
                .width          = QCIF_WIDTH,
                .height         = QCIF_HEIGHT,
                .com7_bit       = COM7_FMT_VGA, /* see comment above */
                .hstart         = 456,          /* Empirically determined */
                .hstop          =  24,
                .vstart         =  14,
                .vstop          = 494,
                .regs           = ov7670_qcif_regs,
        },
};

#define N_WIN_SIZES (ARRAY_SIZE(ov7670_win_sizes))


/*
 * Store a set of start/stop values into the camera.
 */
static int ov7670_set_hw(struct v4l2_subdev *sd, 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(sd, REG_HSTART, (hstart >> 3) & 0xff);
        ret += ov7670_write(sd, REG_HSTOP, (hstop >> 3) & 0xff);
        ret += ov7670_read(sd, REG_HREF, &v);
        v = (v & 0xc0) | ((hstop & 0x7) << 3) | (hstart & 0x7);
        msleep(10);
        ret += ov7670_write(sd, REG_HREF, v);
/*
 * Vertical: similar arrangement, but only 10 bits.
 */
        ret += ov7670_write(sd, REG_VSTART, (vstart >> 2) & 0xff);
        ret += ov7670_write(sd, REG_VSTOP, (vstop >> 2) & 0xff);
        ret += ov7670_read(sd, REG_VREF, &v);
        v = (v & 0xf0) | ((vstop & 0x3) << 2) | (vstart & 0x3);
        msleep(10);
        ret += ov7670_write(sd, REG_VREF, v);
        return ret;
}


static int ov7670_enum_mbus_fmt(struct v4l2_subdev *sd, unsigned index,
                                        enum v4l2_mbus_pixelcode *code)
{
        if (index >= N_OV7670_FMTS)
                return -EINVAL;

        *code = ov7670_formats[index].mbus_code;
        return 0;
}

static int ov7670_try_fmt_internal(struct v4l2_subdev *sd,
                struct v4l2_mbus_framefmt *fmt,
                struct ov7670_format_struct **ret_fmt,
                struct ov7670_win_size **ret_wsize)
{
        int index;
        struct ov7670_win_size *wsize;

        for (index = 0; index < N_OV7670_FMTS; index++)
                if (ov7670_formats[index].mbus_code == fmt->code)
                        break;
        if (index >= N_OV7670_FMTS) {
                /* default to first format */
                index = 0;
                fmt->code = ov7670_formats[0].mbus_code;
        }
        if (ret_fmt != NULL)
                *ret_fmt = ov7670_formats + index;
        /*
         * Fields: the OV devices claim to be progressive.
         */
        fmt->field = V4L2_FIELD_NONE;
        /*
         * 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 (fmt->width >= wsize->width && fmt->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.
         */
        fmt->width = wsize->width;
        fmt->height = wsize->height;
        fmt->colorspace = ov7670_formats[index].colorspace;
        return 0;
}

static int ov7670_try_mbus_fmt(struct v4l2_subdev *sd,
                            struct v4l2_mbus_framefmt *fmt)
{
        return ov7670_try_fmt_internal(sd, fmt, NULL, NULL);
}

/*
 * Set a format.
 */
static int ov7670_s_mbus_fmt(struct v4l2_subdev *sd,
                          struct v4l2_mbus_framefmt *fmt)
{
        struct ov7670_format_struct *ovfmt;
        struct ov7670_win_size *wsize;
        struct ov7670_info *info = to_state(sd);
        unsigned char com7;
        int ret;

        ret = ov7670_try_fmt_internal(sd, 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(sd, REG_COM7, com7);
        /*
         * Now write the rest of the array.  Also store start/stops
         */
        ov7670_write_array(sd, ovfmt->regs + 1);
        ov7670_set_hw(sd, wsize->hstart, wsize->hstop, wsize->vstart,
                        wsize->vstop);
        ret = 0;
        if (wsize->regs)
                ret = ov7670_write_array(sd, wsize->regs);
        info->fmt = ovfmt;

        /*
         * If we're running RGB565, we must rewrite clkrc after setting
         * the other parameters or the image looks poor.  If we're *not*
         * doing RGB565, we must not rewrite clkrc or the image looks
         * *really* poor.
         *
         * (Update) Now that we retain clkrc state, we should be able
         * to write it unconditionally, and that will make the frame
         * rate persistent too.
         */
        if (ret == 0)
                ret = ov7670_write(sd, REG_CLKRC, info->clkrc);
        return 0;
}

/*
 * Implement G/S_PARM.  There is a "high quality" mode we could try
 * to do someday; for now, we just do the frame rate tweak.
 */
static int ov7670_g_parm(struct v4l2_subdev *sd, struct v4l2_streamparm *parms)
{
        struct v4l2_captureparm *cp = &parms->parm.capture;
        struct ov7670_info *info = to_state(sd);

        if (parms->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
                return -EINVAL;

        memset(cp, 0, sizeof(struct v4l2_captureparm));
        cp->capability = V4L2_CAP_TIMEPERFRAME;
        cp->timeperframe.numerator = 1;
        cp->timeperframe.denominator = info->clock_speed;
        if ((info->clkrc & CLK_EXT) == 0 && (info->clkrc & CLK_SCALE) > 1)
                cp->timeperframe.denominator /= (info->clkrc & CLK_SCALE);
        return 0;
}

static int ov7670_s_parm(struct v4l2_subdev *sd, struct v4l2_streamparm *parms)
{
        struct v4l2_captureparm *cp = &parms->parm.capture;
        struct v4l2_fract *tpf = &cp->timeperframe;
        struct ov7670_info *info = to_state(sd);
        int div;

        if (parms->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
                return -EINVAL;
        if (cp->extendedmode != 0)
                return -EINVAL;

        if (tpf->numerator == 0 || tpf->denominator == 0)
                div = 1;  /* Reset to full rate */
        else
                div = (tpf->numerator * info->clock_speed) / tpf->denominator;
        if (div == 0)
                div = 1;
        else if (div > CLK_SCALE)
                div = CLK_SCALE;
        info->clkrc = (info->clkrc & 0x80) | div;
        tpf->numerator = 1;
        tpf->denominator = info->clock_speed / div;
        return ov7670_write(sd, REG_CLKRC, info->clkrc);
}


/*
 * Frame intervals.  Since frame rates are controlled with the clock
 * divider, we can only do 30/n for integer n values.  So no continuous
 * or stepwise options.  Here we just pick a handful of logical values.
 */

static int ov7670_frame_rates[] = { 30, 15, 10, 5, 1 };

static int ov7670_enum_frameintervals(struct v4l2_subdev *sd,
                struct v4l2_frmivalenum *interval)
{
        if (interval->index >= ARRAY_SIZE(ov7670_frame_rates))
                return -EINVAL;
        interval->type = V4L2_FRMIVAL_TYPE_DISCRETE;
        interval->discrete.numerator = 1;
        interval->discrete.denominator = ov7670_frame_rates[interval->index];
        return 0;
}

/*
 * Frame size enumeration
 */
static int ov7670_enum_framesizes(struct v4l2_subdev *sd,
                struct v4l2_frmsizeenum *fsize)
{
        struct ov7670_info *info = to_state(sd);
        int i;
        int num_valid = -1;
        __u32 index = fsize->index;

        /*
         * If a minimum width/height was requested, filter out the capture
         * windows that fall outside that.
         */
        for (i = 0; i < N_WIN_SIZES; i++) {
                struct ov7670_win_size *win = &ov7670_win_sizes[index];
                if (info->min_width && win->width < info->min_width)
                        continue;
                if (info->min_height && win->height < info->min_height)
                        continue;
                if (index == ++num_valid) {
                        fsize->type = V4L2_FRMSIZE_TYPE_DISCRETE;
                        fsize->discrete.width = win->width;
                        fsize->discrete.height = win->height;
                        return 0;
                }
        }

        return -EINVAL;
}

/*
 * Code for dealing with controls.
 */

static int ov7670_store_cmatrix(struct v4l2_subdev *sd,
                int matrix[CMATRIX_LEN])
{
        int i, ret;
        unsigned char signbits = 0;

        /*
         * Weird crap seems to exist in the upper part of
         * the sign bits register, so let's preserve it.
         */
        ret = ov7670_read(sd, REG_CMATRIX_SIGN, &signbits);
        signbits &= 0xc0;

        for (i = 0; i < CMATRIX_LEN; i++) {
                unsigned char raw;

                if (matrix[i] < 0) {
                        signbits |= (1 << i);
                        if (matrix[i] < -255)
                                raw = 0xff;
                        else
                                raw = (-1 * matrix[i]) & 0xff;
                }
                else {
                        if (matrix[i] > 255)
                                raw = 0xff;
                        else
                                raw = matrix[i] & 0xff;
                }
                ret += ov7670_write(sd, REG_CMATRIX_BASE + i, raw);
        }
        ret += ov7670_write(sd, REG_CMATRIX_SIGN, signbits);
        return ret;
}


/*
 * Hue also requires messing with the color matrix.  It also requires
 * trig functions, which tend not to be well supported in the kernel.
 * So here is a simple table of sine values, 0-90 degrees, in steps
 * of five degrees.  Values are multiplied by 1000.

 *
 * The following naive approximate trig functions require an argument
 * carefully limited to -180 <= theta <= 180.
 */
#define SIN_STEP 5
static const int ov7670_sin_table[] = {
           0,    87,   173,   258,   342,   422,
         499,   573,   642,   707,   766,   819,
         866,   906,   939,   965,   984,   996,
        1000
};

static int ov7670_sine(int theta)
{
        int chs = 1;
        int sine;

        if (theta < 0) {
                theta = -theta;
                chs = -1;
        }
        if (theta <= 90)
                sine = ov7670_sin_table[theta/SIN_STEP];
        else {
                theta -= 90;
                sine = 1000 - ov7670_sin_table[theta/SIN_STEP];
        }
        return sine*chs;
}

static int ov7670_cosine(int theta)
{
        theta = 90 - theta;
        if (theta > 180)
                theta -= 360;
        else if (theta < -180)
                theta += 360;
        return ov7670_sine(theta);
}




static void ov7670_calc_cmatrix(struct ov7670_info *info,
                int matrix[CMATRIX_LEN])
{
        int i;
        /*
         * Apply the current saturation setting first.
         */
        for (i = 0; i < CMATRIX_LEN; i++)
                matrix[i] = (info->fmt->cmatrix[i]*info->sat) >> 7;
        /*
         * Then, if need be, rotate the hue value.
         */
        if (info->hue != 0) {
                int sinth, costh, tmpmatrix[CMATRIX_LEN];

                memcpy(tmpmatrix, matrix, CMATRIX_LEN*sizeof(int));
                sinth = ov7670_sine(info->hue);
                costh = ov7670_cosine(info->hue);

                matrix[0] = (matrix[3]*sinth + matrix[0]*costh)/1000;
                matrix[1] = (matrix[4]*sinth + matrix[1]*costh)/1000;
                matrix[2] = (matrix[5]*sinth + matrix[2]*costh)/1000;
                matrix[3] = (matrix[3]*costh - matrix[0]*sinth)/1000;
                matrix[4] = (matrix[4]*costh - matrix[1]*sinth)/1000;
                matrix[5] = (matrix[5]*costh - matrix[2]*sinth)/1000;
        }
}



static int ov7670_s_sat(struct v4l2_subdev *sd, int value)
{
        struct ov7670_info *info = to_state(sd);
        int matrix[CMATRIX_LEN];
        int ret;

        info->sat = value;
        ov7670_calc_cmatrix(info, matrix);
        ret = ov7670_store_cmatrix(sd, matrix);
        return ret;
}

static int ov7670_g_sat(struct v4l2_subdev *sd, __s32 *value)
{
        struct ov7670_info *info = to_state(sd);

        *value = info->sat;
        return 0;
}

static int ov7670_s_hue(struct v4l2_subdev *sd, int value)
{
        struct ov7670_info *info = to_state(sd);
        int matrix[CMATRIX_LEN];
        int ret;

        if (value < -180 || value > 180)
                return -EINVAL;
        info->hue = value;
        ov7670_calc_cmatrix(info, matrix);
        ret = ov7670_store_cmatrix(sd, matrix);
        return ret;
}


static int ov7670_g_hue(struct v4l2_subdev *sd, __s32 *value)
{
        struct ov7670_info *info = to_state(sd);

        *value = info->hue;
        return 0;
}


/*
 * 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;
        return 128 - (v & 0x7f);
}


static unsigned char ov7670_abs_to_sm(unsigned char v)
{
        if (v > 127)
                return v & 0x7f;
        return (128 - v) | 0x80;
}

static int ov7670_s_brightness(struct v4l2_subdev *sd, int value)
{
        unsigned char com8 = 0, v;
        int ret;

        ov7670_read(sd, REG_COM8, &com8);
        com8 &= ~COM8_AEC;
        ov7670_write(sd, REG_COM8, com8);
        v = ov7670_abs_to_sm(value);
        ret = ov7670_write(sd, REG_BRIGHT, v);
        return ret;
}

static int ov7670_g_brightness(struct v4l2_subdev *sd, __s32 *value)
{
        unsigned char v = 0;
        int ret = ov7670_read(sd, REG_BRIGHT, &v);

        *value = ov7670_sm_to_abs(v);
        return ret;
}

static int ov7670_s_contrast(struct v4l2_subdev *sd, int value)
{
        return ov7670_write(sd, REG_CONTRAS, (unsigned char) value);
}

static int ov7670_g_contrast(struct v4l2_subdev *sd, __s32 *value)
{
        unsigned char v = 0;
        int ret = ov7670_read(sd, REG_CONTRAS, &v);

        *value = v;
        return ret;
}

static int ov7670_g_hflip(struct v4l2_subdev *sd, __s32 *value)
{
        int ret;
        unsigned char v = 0;

        ret = ov7670_read(sd, REG_MVFP, &v);
        *value = (v & MVFP_MIRROR) == MVFP_MIRROR;
        return ret;
}


static int ov7670_s_hflip(struct v4l2_subdev *sd, int value)
{
        unsigned char v = 0;
        int ret;

        ret = ov7670_read(sd, REG_MVFP, &v);
        if (value)
                v |= MVFP_MIRROR;
        else
                v &= ~MVFP_MIRROR;
        msleep(10);  /* FIXME */
        ret += ov7670_write(sd, REG_MVFP, v);
        return ret;
}



static int ov7670_g_vflip(struct v4l2_subdev *sd, __s32 *value)
{
        int ret;
        unsigned char v = 0;

        ret = ov7670_read(sd, REG_MVFP, &v);
        *value = (v & MVFP_FLIP) == MVFP_FLIP;
        return ret;
}


static int ov7670_s_vflip(struct v4l2_subdev *sd, int value)
{
        unsigned char v = 0;
        int ret;

        ret = ov7670_read(sd, REG_MVFP, &v);
        if (value)
                v |= MVFP_FLIP;
        else
                v &= ~MVFP_FLIP;
        msleep(10);  /* FIXME */
        ret += ov7670_write(sd, REG_MVFP, v);
        return ret;
}

/*
 * GAIN is split between REG_GAIN and REG_VREF[7:6].  If one believes
 * the data sheet, the VREF parts should be the most significant, but
 * experience shows otherwise.  There seems to be little value in
 * messing with the VREF bits, so we leave them alone.
 */
static int ov7670_g_gain(struct v4l2_subdev *sd, __s32 *value)
{
        int ret;
        unsigned char gain;

        ret = ov7670_read(sd, REG_GAIN, &gain);
        *value = gain;
        return ret;
}

static int ov7670_s_gain(struct v4l2_subdev *sd, int value)
{
        int ret;
        unsigned char com8;

        ret = ov7670_write(sd, REG_GAIN, value & 0xff);
        /* Have to turn off AGC as well */
        if (ret == 0) {
                ret = ov7670_read(sd, REG_COM8, &com8);
                ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AGC);
        }
        return ret;
}

/*
 * Tweak autogain.
 */
static int ov7670_g_autogain(struct v4l2_subdev *sd, __s32 *value)
{
        int ret;
        unsigned char com8;

        ret = ov7670_read(sd, REG_COM8, &com8);
        *value = (com8 & COM8_AGC) != 0;
        return ret;
}

static int ov7670_s_autogain(struct v4l2_subdev *sd, int value)
{
        int ret;
        unsigned char com8;

        ret = ov7670_read(sd, REG_COM8, &com8);
        if (ret == 0) {
                if (value)
                        com8 |= COM8_AGC;
                else
                        com8 &= ~COM8_AGC;
                ret = ov7670_write(sd, REG_COM8, com8);
        }
        return ret;
}

/*
 * Exposure is spread all over the place: top 6 bits in AECHH, middle
 * 8 in AECH, and two stashed in COM1 just for the hell of it.
 */
static int ov7670_g_exp(struct v4l2_subdev *sd, __s32 *value)
{
        int ret;
        unsigned char com1, aech, aechh;

        ret = ov7670_read(sd, REG_COM1, &com1) +
                ov7670_read(sd, REG_AECH, &aech) +
                ov7670_read(sd, REG_AECHH, &aechh);
        *value = ((aechh & 0x3f) << 10) | (aech << 2) | (com1 & 0x03);
        return ret;
}

static int ov7670_s_exp(struct v4l2_subdev *sd, int value)
{
        int ret;
        unsigned char com1, com8, aech, aechh;

        ret = ov7670_read(sd, REG_COM1, &com1) +
                ov7670_read(sd, REG_COM8, &com8);
                ov7670_read(sd, REG_AECHH, &aechh);
        if (ret)
                return ret;

        com1 = (com1 & 0xfc) | (value & 0x03);
        aech = (value >> 2) & 0xff;
        aechh = (aechh & 0xc0) | ((value >> 10) & 0x3f);
        ret = ov7670_write(sd, REG_COM1, com1) +
                ov7670_write(sd, REG_AECH, aech) +
                ov7670_write(sd, REG_AECHH, aechh);
        /* Have to turn off AEC as well */
        if (ret == 0)
                ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AEC);
        return ret;
}

/*
 * Tweak autoexposure.
 */
static int ov7670_g_autoexp(struct v4l2_subdev *sd, __s32 *value)
{
        int ret;
        unsigned char com8;
        enum v4l2_exposure_auto_type *atype = (enum v4l2_exposure_auto_type *) value;

        ret = ov7670_read(sd, REG_COM8, &com8);
        if (com8 & COM8_AEC)
                *atype = V4L2_EXPOSURE_AUTO;
        else
                *atype = V4L2_EXPOSURE_MANUAL;
        return ret;
}

static int ov7670_s_autoexp(struct v4l2_subdev *sd,
                enum v4l2_exposure_auto_type value)
{
        int ret;
        unsigned char com8;

        ret = ov7670_read(sd, REG_COM8, &com8);
        if (ret == 0) {
                if (value == V4L2_EXPOSURE_AUTO)
                        com8 |= COM8_AEC;
                else
                        com8 &= ~COM8_AEC;
                ret = ov7670_write(sd, REG_COM8, com8);
        }
        return ret;
}



static int ov7670_queryctrl(struct v4l2_subdev *sd,
                struct v4l2_queryctrl *qc)
{
        /* Fill in min, max, step and default value for these controls. */
        switch (qc->id) {
        case V4L2_CID_BRIGHTNESS:
                return v4l2_ctrl_query_fill(qc, 0, 255, 1, 128);
        case V4L2_CID_CONTRAST:
                return v4l2_ctrl_query_fill(qc, 0, 127, 1, 64);
        case V4L2_CID_VFLIP:
        case V4L2_CID_HFLIP:
                return v4l2_ctrl_query_fill(qc, 0, 1, 1, 0);
        case V4L2_CID_SATURATION:
                return v4l2_ctrl_query_fill(qc, 0, 256, 1, 128);
        case V4L2_CID_HUE:
                return v4l2_ctrl_query_fill(qc, -180, 180, 5, 0);
        case V4L2_CID_GAIN:
                return v4l2_ctrl_query_fill(qc, 0, 255, 1, 128);
        case V4L2_CID_AUTOGAIN:
                return v4l2_ctrl_query_fill(qc, 0, 1, 1, 1);
        case V4L2_CID_EXPOSURE:
                return v4l2_ctrl_query_fill(qc, 0, 65535, 1, 500);
        case V4L2_CID_EXPOSURE_AUTO:
                return v4l2_ctrl_query_fill(qc, 0, 1, 1, 0);
        }
        return -EINVAL;
}

static int ov7670_g_ctrl(struct v4l2_subdev *sd, struct v4l2_control *ctrl)
{
        switch (ctrl->id) {
        case V4L2_CID_BRIGHTNESS:
                return ov7670_g_brightness(sd, &ctrl->value);
        case V4L2_CID_CONTRAST:
                return ov7670_g_contrast(sd, &ctrl->value);
        case V4L2_CID_SATURATION:
                return ov7670_g_sat(sd, &ctrl->value);
        case V4L2_CID_HUE:
                return ov7670_g_hue(sd, &ctrl->value);
        case V4L2_CID_VFLIP:
                return ov7670_g_vflip(sd, &ctrl->value);
        case V4L2_CID_HFLIP:
                return ov7670_g_hflip(sd, &ctrl->value);
        case V4L2_CID_GAIN:
                return ov7670_g_gain(sd, &ctrl->value);
        case V4L2_CID_AUTOGAIN:
                return ov7670_g_autogain(sd, &ctrl->value);
        case V4L2_CID_EXPOSURE:
                return ov7670_g_exp(sd, &ctrl->value);
        case V4L2_CID_EXPOSURE_AUTO:
                return ov7670_g_autoexp(sd, &ctrl->value);
        }
        return -EINVAL;
}

static int ov7670_s_ctrl(struct v4l2_subdev *sd, struct v4l2_control *ctrl)
{
        switch (ctrl->id) {
        case V4L2_CID_BRIGHTNESS:
                return ov7670_s_brightness(sd, ctrl->value);
        case V4L2_CID_CONTRAST:
                return ov7670_s_contrast(sd, ctrl->value);
        case V4L2_CID_SATURATION:
                return ov7670_s_sat(sd, ctrl->value);
        case V4L2_CID_HUE:
                return ov7670_s_hue(sd, ctrl->value);
        case V4L2_CID_VFLIP:
                return ov7670_s_vflip(sd, ctrl->value);
        case V4L2_CID_HFLIP:
                return ov7670_s_hflip(sd, ctrl->value);
        case V4L2_CID_GAIN:
                return ov7670_s_gain(sd, ctrl->value);
        case V4L2_CID_AUTOGAIN:
                return ov7670_s_autogain(sd, ctrl->value);
        case V4L2_CID_EXPOSURE:
                return ov7670_s_exp(sd, ctrl->value);
        case V4L2_CID_EXPOSURE_AUTO:
                return ov7670_s_autoexp(sd,
                                (enum v4l2_exposure_auto_type) ctrl->value);
        }
        return -EINVAL;
}

static int ov7670_g_chip_ident(struct v4l2_subdev *sd,
                struct v4l2_dbg_chip_ident *chip)
{
        struct i2c_client *client = v4l2_get_subdevdata(sd);

        return v4l2_chip_ident_i2c_client(client, chip, V4L2_IDENT_OV7670, 0);
}

#ifdef CONFIG_VIDEO_ADV_DEBUG
static int ov7670_g_register(struct v4l2_subdev *sd, struct v4l2_dbg_register *reg)
{
        struct i2c_client *client = v4l2_get_subdevdata(sd);
        unsigned char val = 0;
        int ret;

        if (!v4l2_chip_match_i2c_client(client, &reg->match))
                return -EINVAL;
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
        ret = ov7670_read(sd, reg->reg & 0xff, &val);
        reg->val = val;
        reg->size = 1;
        return ret;
}

static int ov7670_s_register(struct v4l2_subdev *sd, struct v4l2_dbg_register *reg)
{
        struct i2c_client *client = v4l2_get_subdevdata(sd);

        if (!v4l2_chip_match_i2c_client(client, &reg->match))
                return -EINVAL;
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
        ov7670_write(sd, reg->reg & 0xff, reg->val & 0xff);
        return 0;
}
#endif

/* ----------------------------------------------------------------------- */

static const struct v4l2_subdev_core_ops ov7670_core_ops = {
        .g_chip_ident = ov7670_g_chip_ident,
        .g_ctrl = ov7670_g_ctrl,
        .s_ctrl = ov7670_s_ctrl,
        .queryctrl = ov7670_queryctrl,
        .reset = ov7670_reset,
        .init = ov7670_init,
#ifdef CONFIG_VIDEO_ADV_DEBUG
        .g_register = ov7670_g_register,
        .s_register = ov7670_s_register,
#endif
};

static const struct v4l2_subdev_video_ops ov7670_video_ops = {
        .enum_mbus_fmt = ov7670_enum_mbus_fmt,
        .try_mbus_fmt = ov7670_try_mbus_fmt,
        .s_mbus_fmt = ov7670_s_mbus_fmt,
        .s_parm = ov7670_s_parm,
        .g_parm = ov7670_g_parm,
        .enum_frameintervals = ov7670_enum_frameintervals,
        .enum_framesizes = ov7670_enum_framesizes,
};

static const struct v4l2_subdev_ops ov7670_ops = {
        .core = &ov7670_core_ops,
        .video = &ov7670_video_ops,
};

/* ----------------------------------------------------------------------- */

static int ov7670_probe(struct i2c_client *client,
                        const struct i2c_device_id *id)
{
        struct v4l2_subdev *sd;
        struct ov7670_info *info;
        int ret;

        info = kzalloc(sizeof(struct ov7670_info), GFP_KERNEL);
        if (info == NULL)
                return -ENOMEM;
        sd = &info->sd;
        v4l2_i2c_subdev_init(sd, client, &ov7670_ops);

        info->clock_speed = 30; /* default: a guess */
        if (client->dev.platform_data) {
                struct ov7670_config *config = client->dev.platform_data;

                /*
                 * Must apply configuration before initializing device, because it
                 * selects I/O method.
                 */
                info->min_width = config->min_width;
                info->min_height = config->min_height;
                info->use_smbus = config->use_smbus;

                if (config->clock_speed)
                        info->clock_speed = config->clock_speed;
        }

        /* Make sure it's an ov7670 */
        ret = ov7670_detect(sd);
        if (ret) {
                v4l_dbg(1, debug, client,
                        "chip found @ 0x%x (%s) is not an ov7670 chip.\n",
                        client->addr << 1, client->adapter->name);
                kfree(info);
                return ret;
        }
        v4l_info(client, "chip found @ 0x%02x (%s)\n",
                        client->addr << 1, client->adapter->name);

        info->fmt = &ov7670_formats[0];
        info->sat = 128;        /* Review this */
        info->clkrc = info->clock_speed / 30;
        return 0;
}


static int ov7670_remove(struct i2c_client *client)
{
        struct v4l2_subdev *sd = i2c_get_clientdata(client);

        v4l2_device_unregister_subdev(sd);
        kfree(to_state(sd));
        return 0;
}

static const struct i2c_device_id ov7670_id[] = {
        { "ov7670", 0 },
        { }
};
MODULE_DEVICE_TABLE(i2c, ov7670_id);

static struct i2c_driver ov7670_driver = {
        .driver = {
                .owner  = THIS_MODULE,
                .name   = "ov7670",
        },
        .probe          = ov7670_probe,
        .remove         = ov7670_remove,
        .id_table       = ov7670_id,
};

module_i2c_driver(ov7670_driver);