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ov7670.c

/*
 * 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/delay.h>
#include <linux/videodev.h>
#include <media/v4l2-common.h>
#include <media/v4l2-chip-ident.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

/*
 * Our nominal (default) frame rate.
 */
#define OV7670_FRAME_RATE 30

/*
 * 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 ov7670_format_struct *fmt;  /* Current format */
      unsigned char sat;            /* Saturation value */
      int hue;                /* Hue value */
};




/*
 * 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 },
      { 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 },
      { 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, 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" */
      { 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.
 */

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)
{
      int ret = i2c_smbus_write_byte_data(c, reg, value);
      if (reg == REG_COM7 && (value & COM7_RESET))
            msleep(2);  /* Wait for reset to run */
      return ret;
}


/*
 * 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;
}


/*
 * 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 nubmers come from OmniVision.
 */
static struct ov7670_format_struct {
      __u8 *desc;
      __u32 pixelformat;
      struct regval_list *regs;
      int cmatrix[CMATRIX_LEN];
      int bpp;   /* Bytes per pixel */
} ov7670_formats[] = {
      {
            .desc       = "YUYV 4:2:2",
            .pixelformat      = V4L2_PIX_FMT_YUYV,
            .regs             = ov7670_fmt_yuv422,
            .cmatrix    = { 128, -128, 0, -34, -94, 128 },
            .bpp        = 2,
      },
      {
            .desc       = "RGB 444",
            .pixelformat      = V4L2_PIX_FMT_RGB444,
            .regs       = ov7670_fmt_rgb444,
            .cmatrix    = { 179, -179, 0, -61, -176, 228 },
            .bpp        = 2,
      },
      {
            .desc       = "RGB 565",
            .pixelformat      = V4L2_PIX_FMT_RGB565,
            .regs       = ov7670_fmt_rgb565,
            .cmatrix    = { 179, -179, 0, -61, -176, 228 },
            .bpp        = 2,
      },
      {
            .desc       = "Raw RGB Bayer",
            .pixelformat      = V4L2_PIX_FMT_SBGGR8,
            .regs             = ov7670_fmt_raw,
            .cmatrix    = { 0, 0, 0, 0, 0, 0 },
            .bpp        = 1
      },
};
#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           = 164,            /* Empirically determined */
            .hstop            =  20,
            .vstart           =  14,
            .vstop            = 494,
            .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 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*ov7670_formats[index].bpp;
      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;
      struct ov7670_info *info = i2c_get_clientdata(c);
      unsigned char com7, clkrc;

      ret = ov7670_try_fmt(c, fmt, &ovfmt, &wsize);
      if (ret)
            return ret;
      /*
       * HACK: if we're running rgb565 we need to grab then rewrite
       * CLKRC.  If we're *not*, however, then rewriting clkrc hoses
       * the colors.
       */
      if (fmt->fmt.pix.pixelformat == V4L2_PIX_FMT_RGB565) {
            ret = ov7670_read(c, REG_CLKRC, &clkrc);
            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);
      ret = 0;
      if (wsize->regs)
            ret = ov7670_write_array(c, wsize->regs);
      info->fmt = ovfmt;

      if (fmt->fmt.pix.pixelformat == V4L2_PIX_FMT_RGB565 && ret == 0)
            ret = ov7670_write(c, REG_CLKRC, clkrc);
      return ret;
}

/*
 * 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 i2c_client *c, struct v4l2_streamparm *parms)
{
      struct v4l2_captureparm *cp = &parms->parm.capture;
      unsigned char clkrc;
      int ret;

      if (parms->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
            return -EINVAL;
      ret = ov7670_read(c, REG_CLKRC, &clkrc);
      if (ret < 0)
            return ret;
      memset(cp, 0, sizeof(struct v4l2_captureparm));
      cp->capability = V4L2_CAP_TIMEPERFRAME;
      cp->timeperframe.numerator = 1;
      cp->timeperframe.denominator = OV7670_FRAME_RATE;
      if ((clkrc & CLK_EXT) == 0 && (clkrc & CLK_SCALE) > 1)
            cp->timeperframe.denominator /= (clkrc & CLK_SCALE);
      return 0;
}

static int ov7670_s_parm(struct i2c_client *c, struct v4l2_streamparm *parms)
{
      struct v4l2_captureparm *cp = &parms->parm.capture;
      struct v4l2_fract *tpf = &cp->timeperframe;
      unsigned char clkrc;
      int ret, div;

      if (parms->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
            return -EINVAL;
      if (cp->extendedmode != 0)
            return -EINVAL;
      /*
       * CLKRC has a reserved bit, so let's preserve it.
       */
      ret = ov7670_read(c, REG_CLKRC, &clkrc);
      if (ret < 0)
            return ret;
      if (tpf->numerator == 0 || tpf->denominator == 0)
            div = 1;  /* Reset to full rate */
      else
            div = (tpf->numerator*OV7670_FRAME_RATE)/tpf->denominator;
      if (div == 0)
            div = 1;
      else if (div > CLK_SCALE)
            div = CLK_SCALE;
      clkrc = (clkrc & 0x80) | div;
      tpf->numerator = 1;
      tpf->denominator = OV7670_FRAME_RATE/div;
      return ov7670_write(c, REG_CLKRC, clkrc);
}



/*
 * Code for dealing with controls.
 */





static int ov7670_store_cmatrix(struct i2c_client *client,
            int matrix[CMATRIX_LEN])
{
      int i, ret;
      unsigned char signbits;

      /*
       * Weird crap seems to exist in the upper part of
       * the sign bits register, so let's preserve it.
       */
      ret = ov7670_read(client, 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(client, REG_CMATRIX_BASE + i, raw);
      }
      ret += ov7670_write(client, 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_t_sat(struct i2c_client *client, int value)
{
      struct ov7670_info *info = i2c_get_clientdata(client);
      int matrix[CMATRIX_LEN];
      int ret;

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

static int ov7670_q_sat(struct i2c_client *client, __s32 *value)
{
      struct ov7670_info *info = i2c_get_clientdata(client);

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

static int ov7670_t_hue(struct i2c_client *client, int value)
{
      struct ov7670_info *info = i2c_get_clientdata(client);
      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(client, matrix);
      return ret;
}


static int ov7670_q_hue(struct i2c_client *client, __s32 *value)
{
      struct ov7670_info *info = i2c_get_clientdata(client);

      *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;
      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, int value)
{
      unsigned char com8, v;
      int ret;

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

static int ov7670_q_brightness(struct i2c_client *client, __s32 *value)
{
      unsigned char v;
      int ret = ov7670_read(client, REG_BRIGHT, &v);

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

static int ov7670_t_contrast(struct i2c_client *client, int value)
{
      return ov7670_write(client, REG_CONTRAS, (unsigned char) value);
}

static int ov7670_q_contrast(struct i2c_client *client, __s32 *value)
{
      unsigned char v;
      int ret = ov7670_read(client, REG_CONTRAS, &v);

      *value = v;
      return ret;
}

static int ov7670_q_hflip(struct i2c_client *client, __s32 *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, int 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, __s32 *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, int 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, __s32 *value);
      int (*tweak)(struct i2c_client *c, int 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_SATURATION,
                  .type = V4L2_CTRL_TYPE_INTEGER,
                  .name = "Saturation",
                  .minimum = 0,
                  .maximum = 256,
                  .step = 1,
                  .default_value = 0x80,
                  .flags = V4L2_CTRL_FLAG_SLIDER
            },
            .tweak = ov7670_t_sat,
            .query = ov7670_q_sat,
      },
      {
            .qc = {
                  .id = V4L2_CID_HUE,
                  .type = V4L2_CTRL_TYPE_INTEGER,
                  .name = "HUE",
                  .minimum = -180,
                  .maximum = 180,
                  .step = 5,
                  .default_value = 0,
                  .flags = V4L2_CTRL_FLAG_SLIDER
            },
            .tweak = ov7670_t_hue,
            .query = ov7670_q_hue,
      },
      {
            .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 (ARRAY_SIZE(ov7670_controls))

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;

      if (octrl == NULL)
            return -EINVAL;
      ret = octrl->query(client, &ctrl->value);
      if (ret >= 0)
            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);
      int ret;

      if (octrl == NULL)
            return -EINVAL;
      ret =  octrl->tweak(client, ctrl->value);
      if (ret >= 0)
            return 0;
      return ret;
}






/*
 * Basic i2c stuff.
 */
static struct i2c_driver ov7670_driver;

static int ov7670_attach(struct i2c_adapter *adapter)
{
      int ret;
      struct i2c_client *client;
      struct ov7670_info *info;

      /*
       * For now: only deal with adapters we recognize.
       */
      if (adapter->id != I2C_HW_SMBUS_CAFE)
            return -ENODEV;

      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");
      /*
       * Set up our info structure.
       */
      info = kzalloc(sizeof (struct ov7670_info), GFP_KERNEL);
      if (! info) {
            ret = -ENOMEM;
            goto out_free;
      }
      info->fmt = &ov7670_formats[0];
      info->sat = 128;  /* Review this */
      i2c_set_clientdata(client, info);

      /*
       * Make sure it's an ov7670
       */
      ret = ov7670_detect(client);
      if (ret)
            goto out_free_info;
      ret = i2c_attach_client(client);
      if (ret)
            goto out_free_info;
      return 0;

  out_free_info:
      kfree(info);
  out_free:
      kfree(client);
      return ret;
}


static int ov7670_detach(struct i2c_client *client)
{
      i2c_detach_client(client);
      kfree(i2c_get_clientdata(client));
      kfree(client);
      return 0;
}


static int ov7670_command(struct i2c_client *client, unsigned int cmd,
            void *arg)
{
      switch (cmd) {
      case VIDIOC_G_CHIP_IDENT:
            return v4l2_chip_ident_i2c_client(client, arg, V4L2_IDENT_OV7670, 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);
      case VIDIOC_S_PARM:
            return ov7670_s_parm(client, (struct v4l2_streamparm *) arg);
      case VIDIOC_G_PARM:
            return ov7670_g_parm(client, (struct v4l2_streamparm *) arg);
      }
      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);

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