mt9t031.c

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/*
 * Driver for MT9T031 CMOS Image Sensor from Micron
 *
 * Copyright (C) 2008, Guennadi Liakhovetski, DENX Software Engineering <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/log2.h>
#include <linux/pm.h>
#include <linux/slab.h>
#include <linux/v4l2-mediabus.h>
#include <linux/videodev2.h>
#include <linux/module.h>

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

/*
 * ATTENTION: this driver still cannot be used outside of the soc-camera
 * framework because of its PM implementation, using the video_device node.
 * If hardware becomes available for testing, alternative PM approaches shall
 * be considered and tested.
 */

/*
 * mt9t031 i2c address 0x5d
 * The platform has to define i2c_board_info and link to it from
 * struct soc_camera_link
 */

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

#define MT9T031_MAX_HEIGHT      1536
#define MT9T031_MAX_WIDTH       2048
#define MT9T031_MIN_HEIGHT      2
#define MT9T031_MIN_WIDTH       18
#define MT9T031_HORIZONTAL_BLANK    142
#define MT9T031_VERTICAL_BLANK      25
#define MT9T031_COLUMN_SKIP     32
#define MT9T031_ROW_SKIP        20

struct mt9t031 {
    struct v4l2_subdev subdev;
    struct v4l2_ctrl_handler hdl;
    struct {
        /* exposure/auto-exposure cluster */
        struct v4l2_ctrl *autoexposure;
        struct v4l2_ctrl *exposure;
    };
    struct v4l2_rect rect;  /* Sensor window */
    int model;  /* V4L2_IDENT_MT9T031* codes from v4l2-chip-ident.h */
    u16 xskip;
    u16 yskip;
    unsigned int total_h;
    unsigned short y_skip_top;  /* Lines to skip at the top */
};

static struct mt9t031 *to_mt9t031(const struct i2c_client *client)
{
    return container_of(i2c_get_clientdata(client), struct mt9t031, subdev);
}

static int reg_read(struct i2c_client *client, const u8 reg)
{
    return i2c_smbus_read_word_swapped(client, reg);
}

static int reg_write(struct i2c_client *client, const u8 reg,
             const u16 data)
{
    return i2c_smbus_write_word_swapped(client, reg, data);
}

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

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

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

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

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

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

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

    return ret;
}

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

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

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

    return ret < 0 ? ret : 0;
}

static int mt9t031_idle(struct i2c_client *client)
{
    int ret;

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

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

static int mt9t031_s_stream(struct v4l2_subdev *sd, int enable)
{
    struct i2c_client *client = v4l2_get_subdevdata(sd);
    int ret;

    if (enable)
        /* Switch to master "normal" mode */
        ret = reg_set(client, MT9T031_OUTPUT_CONTROL, 2);
    else
        /* Stop sensor readout */
        ret = reg_clear(client, MT9T031_OUTPUT_CONTROL, 2);

    if (ret < 0)
        return -EIO;

    return 0;
}

/* target must be _even_ */
static u16 mt9t031_skip(s32 *source, s32 target, s32 max)
{
    unsigned int skip;

    if (*source < target + target / 2) {
        *source = target;
        return 1;
    }

    skip = min(max, *source + target / 2) / target;
    if (skip > 8)
        skip = 8;
    *source = target * skip;

    return skip;
}

/* rect is the sensor rectangle, the caller guarantees parameter validity */
static int mt9t031_set_params(struct i2c_client *client,
                  struct v4l2_rect *rect, u16 xskip, u16 yskip)
{
    struct mt9t031 *mt9t031 = to_mt9t031(client);
    int ret;
    u16 xbin, ybin;
    const u16 hblank = MT9T031_HORIZONTAL_BLANK,
        vblank = MT9T031_VERTICAL_BLANK;

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

    /*
     * Could just do roundup(rect->left, [xy]bin * 2); but this is cheaper.
     * There is always a valid suitably aligned value. The worst case is
     * xbin = 3, width = 2048. Then we will start at 36, the last read out
     * pixel will be 2083, which is < 2085 - first black pixel.
     *
     * MT9T031 datasheet imposes window left border alignment, depending on
     * the selected xskip. Failing to conform to this requirement produces
     * dark horizontal stripes in the image. However, even obeying to this
     * requirement doesn't eliminate the stripes in all configurations. They
     * appear "locally reproducibly," but can differ between tests under
     * different lighting conditions.
     */
    switch (xbin) {
    case 1:
        rect->left &= ~1;
        break;
    case 2:
        rect->left &= ~3;
        break;
    case 3:
        rect->left = rect->left > roundup(MT9T031_COLUMN_SKIP, 6) ?
            (rect->left / 6) * 6 : roundup(MT9T031_COLUMN_SKIP, 6);
    }

    rect->top &= ~1;

    dev_dbg(&client->dev, "skip %u:%u, rect %ux%u@%u:%u\n",
        xskip, yskip, rect->width, rect->height, rect->left, rect->top);

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

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

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

    /*
     * The caller provides a supported format, as guaranteed by
     * .try_mbus_fmt(), soc_camera_s_crop() and soc_camera_cropcap()
     */
    if (ret >= 0)
        ret = reg_write(client, MT9T031_COLUMN_START, rect->left);
    if (ret >= 0)
        ret = reg_write(client, MT9T031_ROW_START, rect->top);
    if (ret >= 0)
        ret = reg_write(client, MT9T031_WINDOW_WIDTH, rect->width - 1);
    if (ret >= 0)
        ret = reg_write(client, MT9T031_WINDOW_HEIGHT,
                rect->height + mt9t031->y_skip_top - 1);
    if (ret >= 0 && v4l2_ctrl_g_ctrl(mt9t031->autoexposure) == V4L2_EXPOSURE_AUTO) {
        mt9t031->total_h = rect->height + mt9t031->y_skip_top + vblank;

        ret = set_shutter(client, mt9t031->total_h);
    }

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

    if (ret >= 0) {
        mt9t031->rect = *rect;
        mt9t031->xskip = xskip;
        mt9t031->yskip = yskip;
    }

    return ret < 0 ? ret : 0;
}

static int mt9t031_s_crop(struct v4l2_subdev *sd, const struct v4l2_crop *a)
{
    struct v4l2_rect rect = a->c;
    struct i2c_client *client = v4l2_get_subdevdata(sd);
    struct mt9t031 *mt9t031 = to_mt9t031(client);

    rect.width = ALIGN(rect.width, 2);
    rect.height = ALIGN(rect.height, 2);

    soc_camera_limit_side(&rect.left, &rect.width,
             MT9T031_COLUMN_SKIP, MT9T031_MIN_WIDTH, MT9T031_MAX_WIDTH);

    soc_camera_limit_side(&rect.top, &rect.height,
             MT9T031_ROW_SKIP, MT9T031_MIN_HEIGHT, MT9T031_MAX_HEIGHT);

    return mt9t031_set_params(client, &rect, mt9t031->xskip, mt9t031->yskip);
}

static int mt9t031_g_crop(struct v4l2_subdev *sd, struct v4l2_crop *a)
{
    struct i2c_client *client = v4l2_get_subdevdata(sd);
    struct mt9t031 *mt9t031 = to_mt9t031(client);

    a->c    = mt9t031->rect;
    a->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

    return 0;
}

static int mt9t031_cropcap(struct v4l2_subdev *sd, struct v4l2_cropcap *a)
{
    a->bounds.left          = MT9T031_COLUMN_SKIP;
    a->bounds.top           = MT9T031_ROW_SKIP;
    a->bounds.width         = MT9T031_MAX_WIDTH;
    a->bounds.height        = MT9T031_MAX_HEIGHT;
    a->defrect          = a->bounds;
    a->type             = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    a->pixelaspect.numerator    = 1;
    a->pixelaspect.denominator  = 1;

    return 0;
}

static int mt9t031_g_fmt(struct v4l2_subdev *sd,
             struct v4l2_mbus_framefmt *mf)
{
    struct i2c_client *client = v4l2_get_subdevdata(sd);
    struct mt9t031 *mt9t031 = to_mt9t031(client);

    mf->width   = mt9t031->rect.width / mt9t031->xskip;
    mf->height  = mt9t031->rect.height / mt9t031->yskip;
    mf->code    = V4L2_MBUS_FMT_SBGGR10_1X10;
    mf->colorspace  = V4L2_COLORSPACE_SRGB;
    mf->field   = V4L2_FIELD_NONE;

    return 0;
}

static int mt9t031_s_fmt(struct v4l2_subdev *sd,
             struct v4l2_mbus_framefmt *mf)
{
    struct i2c_client *client = v4l2_get_subdevdata(sd);
    struct mt9t031 *mt9t031 = to_mt9t031(client);
    u16 xskip, yskip;
    struct v4l2_rect rect = mt9t031->rect;

    /*
     * try_fmt has put width and height within limits.
     * S_FMT: use binning and skipping for scaling
     */
    xskip = mt9t031_skip(&rect.width, mf->width, MT9T031_MAX_WIDTH);
    yskip = mt9t031_skip(&rect.height, mf->height, MT9T031_MAX_HEIGHT);

    mf->code    = V4L2_MBUS_FMT_SBGGR10_1X10;
    mf->colorspace  = V4L2_COLORSPACE_SRGB;

    /* mt9t031_set_params() doesn't change width and height */
    return mt9t031_set_params(client, &rect, xskip, yskip);
}

/*
 * If a user window larger than sensor window is requested, we'll increase the
 * sensor window.
 */
static int mt9t031_try_fmt(struct v4l2_subdev *sd,
               struct v4l2_mbus_framefmt *mf)
{
    v4l_bound_align_image(
        &mf->width, MT9T031_MIN_WIDTH, MT9T031_MAX_WIDTH, 1,
        &mf->height, MT9T031_MIN_HEIGHT, MT9T031_MAX_HEIGHT, 1, 0);

    mf->code    = V4L2_MBUS_FMT_SBGGR10_1X10;
    mf->colorspace  = V4L2_COLORSPACE_SRGB;

    return 0;
}

static int mt9t031_g_chip_ident(struct v4l2_subdev *sd,
                struct v4l2_dbg_chip_ident *id)
{
    struct i2c_client *client = v4l2_get_subdevdata(sd);
    struct mt9t031 *mt9t031 = to_mt9t031(client);

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

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

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

    return 0;
}

#ifdef CONFIG_VIDEO_ADV_DEBUG
static int mt9t031_g_register(struct v4l2_subdev *sd,
                  struct v4l2_dbg_register *reg)
{
    struct i2c_client *client = v4l2_get_subdevdata(sd);

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

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

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

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

    return 0;
}

static int mt9t031_s_register(struct v4l2_subdev *sd,
                  struct v4l2_dbg_register *reg)
{
    struct i2c_client *client = v4l2_get_subdevdata(sd);

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

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

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

    return 0;
}
#endif

static int mt9t031_g_volatile_ctrl(struct v4l2_ctrl *ctrl)
{
    struct mt9t031 *mt9t031 = container_of(ctrl->handler,
                           struct mt9t031, hdl);
    const u32 shutter_max = MT9T031_MAX_HEIGHT + MT9T031_VERTICAL_BLANK;
    s32 min, max;

    switch (ctrl->id) {
    case V4L2_CID_EXPOSURE_AUTO:
        min = mt9t031->exposure->minimum;
        max = mt9t031->exposure->maximum;
        mt9t031->exposure->val =
            (shutter_max / 2 + (mt9t031->total_h - 1) * (max - min))
                / shutter_max + min;
        break;
    }
    return 0;
}

static int mt9t031_s_ctrl(struct v4l2_ctrl *ctrl)
{
    struct mt9t031 *mt9t031 = container_of(ctrl->handler,
                           struct mt9t031, hdl);
    struct v4l2_subdev *sd = &mt9t031->subdev;
    struct i2c_client *client = v4l2_get_subdevdata(sd);
    struct v4l2_ctrl *exp = mt9t031->exposure;
    int data;

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

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

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

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

    case V4L2_CID_EXPOSURE_AUTO:
        if (ctrl->val == V4L2_EXPOSURE_MANUAL) {
            unsigned int range = exp->maximum - exp->minimum;
            unsigned int shutter = ((exp->val - exp->minimum) * 1048 +
                         range / 2) / range + 1;
            u32 old;

            get_shutter(client, &old);
            dev_dbg(&client->dev, "Set shutter from %u to %u\n",
                old, shutter);
            if (set_shutter(client, shutter) < 0)
                return -EIO;
        } else {
            const u16 vblank = MT9T031_VERTICAL_BLANK;
            mt9t031->total_h = mt9t031->rect.height +
                mt9t031->y_skip_top + vblank;

            if (set_shutter(client, mt9t031->total_h) < 0)
                return -EIO;
        }
        return 0;
    default:
        return -EINVAL;
    }
    return 0;
}

/*
 * Power Management:
 * This function does nothing for now but must be present for pm to work
 */
static int mt9t031_runtime_suspend(struct device *dev)
{
    return 0;
}

/*
 * Power Management:
 * COLUMN_ADDRESS_MODE and ROW_ADDRESS_MODE are not rewritten if unchanged
 * they are however changed at reset if the platform hook is present
 * thus we rewrite them with the values stored by the driver
 */
static int mt9t031_runtime_resume(struct device *dev)
{
    struct video_device *vdev = to_video_device(dev);
    struct v4l2_subdev *sd = soc_camera_vdev_to_subdev(vdev);
    struct i2c_client *client = v4l2_get_subdevdata(sd);
    struct mt9t031 *mt9t031 = to_mt9t031(client);

    int ret;
    u16 xbin, ybin;

    xbin = min(mt9t031->xskip, (u16)3);
    ybin = min(mt9t031->yskip, (u16)3);

    ret = reg_write(client, MT9T031_COLUMN_ADDRESS_MODE,
        ((xbin - 1) << 4) | (mt9t031->xskip - 1));
    if (ret < 0)
        return ret;

    ret = reg_write(client, MT9T031_ROW_ADDRESS_MODE,
        ((ybin - 1) << 4) | (mt9t031->yskip - 1));
    if (ret < 0)
        return ret;

    return 0;
}

static struct dev_pm_ops mt9t031_dev_pm_ops = {
    .runtime_suspend    = mt9t031_runtime_suspend,
    .runtime_resume     = mt9t031_runtime_resume,
};

static struct device_type mt9t031_dev_type = {
    .name   = "MT9T031",
    .pm = &mt9t031_dev_pm_ops,
};

static int mt9t031_s_power(struct v4l2_subdev *sd, int on)
{
    struct i2c_client *client = v4l2_get_subdevdata(sd);
    struct soc_camera_link *icl = soc_camera_i2c_to_link(client);
    struct video_device *vdev = soc_camera_i2c_to_vdev(client);
    int ret;

    if (on) {
        ret = soc_camera_power_on(&client->dev, icl);
        if (ret < 0)
            return ret;
        vdev->dev.type = &mt9t031_dev_type;
    } else {
        vdev->dev.type = NULL;
        soc_camera_power_off(&client->dev, icl);
    }

    return 0;
}

/*
 * Interface active, can use i2c. If it fails, it can indeed mean, that
 * this wasn't our capture interface, so, we wait for the right one
 */
static int mt9t031_video_probe(struct i2c_client *client)
{
    struct mt9t031 *mt9t031 = to_mt9t031(client);
    s32 data;
    int ret;

    ret = mt9t031_s_power(&mt9t031->subdev, 1);
    if (ret < 0)
        return ret;

    ret = mt9t031_idle(client);
    if (ret < 0) {
        dev_err(&client->dev, "Failed to initialise the camera\n");
        goto done;
    }

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

    switch (data) {
    case 0x1621:
        mt9t031->model = V4L2_IDENT_MT9T031;
        break;
    default:
        dev_err(&client->dev,
            "No MT9T031 chip detected, register read %x\n", data);
        ret = -ENODEV;
        goto done;
    }

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

    ret = v4l2_ctrl_handler_setup(&mt9t031->hdl);

done:
    mt9t031_s_power(&mt9t031->subdev, 0);

    return ret;
}

static int mt9t031_g_skip_top_lines(struct v4l2_subdev *sd, u32 *lines)
{
    struct i2c_client *client = v4l2_get_subdevdata(sd);
    struct mt9t031 *mt9t031 = to_mt9t031(client);

    *lines = mt9t031->y_skip_top;

    return 0;
}

static const struct v4l2_ctrl_ops mt9t031_ctrl_ops = {
    .g_volatile_ctrl = mt9t031_g_volatile_ctrl,
    .s_ctrl = mt9t031_s_ctrl,
};

static struct v4l2_subdev_core_ops mt9t031_subdev_core_ops = {
    .g_chip_ident   = mt9t031_g_chip_ident,
    .s_power    = mt9t031_s_power,
#ifdef CONFIG_VIDEO_ADV_DEBUG
    .g_register = mt9t031_g_register,
    .s_register = mt9t031_s_register,
#endif
};

static int mt9t031_enum_fmt(struct v4l2_subdev *sd, unsigned int index,
                enum v4l2_mbus_pixelcode *code)
{
    if (index)
        return -EINVAL;

    *code = V4L2_MBUS_FMT_SBGGR10_1X10;
    return 0;
}

static int mt9t031_g_mbus_config(struct v4l2_subdev *sd,
                struct v4l2_mbus_config *cfg)
{
    struct i2c_client *client = v4l2_get_subdevdata(sd);
    struct soc_camera_link *icl = soc_camera_i2c_to_link(client);

    cfg->flags = V4L2_MBUS_MASTER | V4L2_MBUS_PCLK_SAMPLE_RISING |
        V4L2_MBUS_PCLK_SAMPLE_FALLING | V4L2_MBUS_HSYNC_ACTIVE_HIGH |
        V4L2_MBUS_VSYNC_ACTIVE_HIGH | V4L2_MBUS_DATA_ACTIVE_HIGH;
    cfg->type = V4L2_MBUS_PARALLEL;
    cfg->flags = soc_camera_apply_board_flags(icl, cfg);

    return 0;
}

static int mt9t031_s_mbus_config(struct v4l2_subdev *sd,
                const struct v4l2_mbus_config *cfg)
{
    struct i2c_client *client = v4l2_get_subdevdata(sd);
    struct soc_camera_link *icl = soc_camera_i2c_to_link(client);

    if (soc_camera_apply_board_flags(icl, cfg) &
        V4L2_MBUS_PCLK_SAMPLE_FALLING)
        return reg_clear(client, MT9T031_PIXEL_CLOCK_CONTROL, 0x8000);
    else
        return reg_set(client, MT9T031_PIXEL_CLOCK_CONTROL, 0x8000);
}

static struct v4l2_subdev_video_ops mt9t031_subdev_video_ops = {
    .s_stream   = mt9t031_s_stream,
    .s_mbus_fmt = mt9t031_s_fmt,
    .g_mbus_fmt = mt9t031_g_fmt,
    .try_mbus_fmt   = mt9t031_try_fmt,
    .s_crop     = mt9t031_s_crop,
    .g_crop     = mt9t031_g_crop,
    .cropcap    = mt9t031_cropcap,
    .enum_mbus_fmt  = mt9t031_enum_fmt,
    .g_mbus_config  = mt9t031_g_mbus_config,
    .s_mbus_config  = mt9t031_s_mbus_config,
};

static struct v4l2_subdev_sensor_ops mt9t031_subdev_sensor_ops = {
    .g_skip_top_lines   = mt9t031_g_skip_top_lines,
};

static struct v4l2_subdev_ops mt9t031_subdev_ops = {
    .core   = &mt9t031_subdev_core_ops,
    .video  = &mt9t031_subdev_video_ops,
    .sensor = &mt9t031_subdev_sensor_ops,
};

static int mt9t031_probe(struct i2c_client *client,
             const struct i2c_device_id *did)
{
    struct mt9t031 *mt9t031;
    struct soc_camera_link *icl = soc_camera_i2c_to_link(client);
    struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
    int ret;

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

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

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

    v4l2_i2c_subdev_init(&mt9t031->subdev, client, &mt9t031_subdev_ops);
    v4l2_ctrl_handler_init(&mt9t031->hdl, 5);
    v4l2_ctrl_new_std(&mt9t031->hdl, &mt9t031_ctrl_ops,
            V4L2_CID_VFLIP, 0, 1, 1, 0);
    v4l2_ctrl_new_std(&mt9t031->hdl, &mt9t031_ctrl_ops,
            V4L2_CID_HFLIP, 0, 1, 1, 0);
    v4l2_ctrl_new_std(&mt9t031->hdl, &mt9t031_ctrl_ops,
            V4L2_CID_GAIN, 0, 127, 1, 64);

    /*
     * Simulated autoexposure. If enabled, we calculate shutter width
     * ourselves in the driver based on vertical blanking and frame width
     */
    mt9t031->autoexposure = v4l2_ctrl_new_std_menu(&mt9t031->hdl,
            &mt9t031_ctrl_ops, V4L2_CID_EXPOSURE_AUTO, 1, 0,
            V4L2_EXPOSURE_AUTO);
    mt9t031->exposure = v4l2_ctrl_new_std(&mt9t031->hdl, &mt9t031_ctrl_ops,
            V4L2_CID_EXPOSURE, 1, 255, 1, 255);

    mt9t031->subdev.ctrl_handler = &mt9t031->hdl;
    if (mt9t031->hdl.error) {
        int err = mt9t031->hdl.error;

        kfree(mt9t031);
        return err;
    }
    v4l2_ctrl_auto_cluster(2, &mt9t031->autoexposure,
                V4L2_EXPOSURE_MANUAL, true);

    mt9t031->y_skip_top = 0;
    mt9t031->rect.left  = MT9T031_COLUMN_SKIP;
    mt9t031->rect.top   = MT9T031_ROW_SKIP;
    mt9t031->rect.width = MT9T031_MAX_WIDTH;
    mt9t031->rect.height    = MT9T031_MAX_HEIGHT;

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

    ret = mt9t031_video_probe(client);
    if (ret) {
        v4l2_ctrl_handler_free(&mt9t031->hdl);
        kfree(mt9t031);
    }

    return ret;
}

static int mt9t031_remove(struct i2c_client *client)
{
    struct mt9t031 *mt9t031 = to_mt9t031(client);

    v4l2_device_unregister_subdev(&mt9t031->subdev);
    v4l2_ctrl_handler_free(&mt9t031->hdl);
    kfree(mt9t031);

    return 0;
}

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

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

module_i2c_driver(mt9t031_i2c_driver);

MODULE_DESCRIPTION("Micron MT9T031 Camera driver");
MODULE_AUTHOR("Guennadi Liakhovetski <[email protected]>");
MODULE_LICENSE("GPL v2");