了解视频驱动的帮帮小弟！（源码贴）

Question

我现在做关于sensor的驱动调试，需要调试的是mt9p031的sensor，目前只有一个关于mt9v011的程序实例，本人不知道该如何入手解决问题，现在手上的资料有mt9p031和mt9v011的 datesheet。其他就没什么了，本人目前将mt9v011的驱动加入到开发板上，但什么都不显示，是否还需要相关的应用程序开启摄像头呢？
请各位高手帮帮小弟，跪谢了！
/*
* mt9v011 -Micron 1/4-Inch VGA Digital Image Sensor
*
* Copyright (c) 2009 Mauro Carvalho Chehab (mchehab@redhat.com)
* This code is placed under the terms of the GNU General Public License v2
*/

#include <linux/i2c.h>
#include <linux/videodev2.h>
#include <linux/delay.h>
#include <asm/div64.h>
#include <media/v4l2-device.h>
#include "mt9v011.h"
#include <media/v4l2-i2c-drv.h>
#include <media/v4l2-chip-ident.h>

MODULE_DESCRIPTION("Micron mt9v011 sensor driver";
MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>";
MODULE_LICENSE("GPL";

static int debug;
module_param(debug, int, 0);
MODULE_PARM_DESC(debug, "Debug level (0-2)";

/* supported controls */
static struct v4l2_queryctrl mt9v011_qctrl[] = {
        {
                .id = V4L2_CID_GAIN,
                .type = V4L2_CTRL_TYPE_INTEGER,
                .name = "Gain",
                .minimum = 0,
                .maximum = (1 << 10) - 1,
                .step = 1,
                .default_value = 0x0020,
                .flags = 0,
        }, {
                .id = V4L2_CID_RED_BALANCE,
                .type = V4L2_CTRL_TYPE_INTEGER,
                .name = "Red Balance",
                .minimum = -1 << 9,
                .maximum = (1 << 9) - 1,
                .step = 1,
                .default_value = 0,
                .flags = 0,
        }, {
                .id = V4L2_CID_BLUE_BALANCE,
                .type = V4L2_CTRL_TYPE_INTEGER,
                .name = "Blue Balance",
                .minimum = -1 << 9,
                .maximum = (1 << 9) - 1,
                .step = 1,
                .default_value = 0,
                .flags = 0,
        }, {
                .id      = V4L2_CID_HFLIP,
                .type    = V4L2_CTRL_TYPE_BOOLEAN,
                .name    = "Mirror",
                .minimum = 0,
                .maximum = 1,
                .step    = 1,
                .default_value = 0,
                .flags = 0,
        }, {
                .id      = V4L2_CID_VFLIP,
                .type    = V4L2_CTRL_TYPE_BOOLEAN,
                .name    = "Vflip",
                .minimum = 0,
                .maximum = 1,
                .step    = 1,
                .default_value = 0,
                .flags = 0,
        }, {
        }
};

struct mt9v011 {
        struct v4l2_subdev sd;
        unsigned width, height;
        unsigned xtal;
        unsigned hflip:1;
        unsigned vflip:1;

        u16 global_gain, red_bal, blue_bal;
};

static inline struct mt9v011 *to_mt9v011(struct v4l2_subdev *sd)
{
        return container_of(sd, struct mt9v011, sd);
}

static int mt9v011_read(struct v4l2_subdev *sd, unsigned char addr)
{
        struct i2c_client *c = v4l2_get_subdevdata(sd);
        __be16 buffer;
        int rc, val;

        rc = i2c_master_send(c, &addr, 1);
        if (rc != 1)
                v4l2_dbg(0, debug, sd,
                         "i2c i/o error: rc == %d (should be 1)\n", rc);

        msleep(10);

        rc = i2c_master_recv(c, (char *)&buffer, 2);
        if (rc != 2)
                v4l2_dbg(0, debug, sd,
                         "i2c i/o error: rc == %d (should be 2)\n", rc);

        val = be16_to_cpu(buffer);

        v4l2_dbg(2, debug, sd, "mt9v011: read 0x%02x = 0x%04x\n", addr, val);

        return val;
}

static void mt9v011_write(struct v4l2_subdev *sd, unsigned char addr,
                                 u16 value)
{
        struct i2c_client *c = v4l2_get_subdevdata(sd);
        unsigned char buffer[3];
        int rc;

        buffer[0] = addr;
        buffer[1] = value >> 8;
        buffer[2] = value & 0xff;

        v4l2_dbg(2, debug, sd,
                 "mt9v011: writing 0x%02x 0x%04x\n", buffer[0], value);
        rc = i2c_master_send(c, buffer, 3);
        if (rc != 3)
                v4l2_dbg(0, debug, sd,
                         "i2c i/o error: rc == %d (should be 3)\n", rc);
}

struct i2c_reg_value {
        unsigned char reg;
        u16           value;
};

/*
* Values used at the original driver
* Some values are marked as Reserved at the datasheet
*/
static const struct i2c_reg_value mt9v011_init_default[] = {
                { R0D_MT9V011_RESET, 0x0001 },
                { R0D_MT9V011_RESET, 0x0000 },

                { R0C_MT9V011_SHUTTER_DELAY, 0x0000 },
                { R09_MT9V011_SHUTTER_WIDTH, 0x1fc },

                { R0A_MT9V011_CLK_SPEED, 0x0000 },
                { R1E_MT9V011_DIGITAL_ZOOM,  0x0000 },

                { R07_MT9V011_OUT_CTRL, 0x0002 },        /* chip enable */
};

static void set_balance(struct v4l2_subdev *sd)
{
        struct mt9v011 *core = to_mt9v011(sd);
        u16 green1_gain, green2_gain, blue_gain, red_gain;

        green1_gain = core->global_gain;
        green2_gain = core->global_gain;

        blue_gain = core->global_gain +
                    core->global_gain * core->blue_bal / (1 << 9);

        red_gain = core->global_gain +
                   core->global_gain * core->blue_bal / (1 << 9);

        mt9v011_write(sd, R2B_MT9V011_GREEN_1_GAIN, green1_gain);
        mt9v011_write(sd, R2E_MT9V011_GREEN_2_GAIN,  green1_gain);
        mt9v011_write(sd, R2C_MT9V011_BLUE_GAIN, blue_gain);
        mt9v011_write(sd, R2D_MT9V011_RED_GAIN, red_gain);
}

static void calc_fps(struct v4l2_subdev *sd, u32 *numerator, u32 *denominator)
{
        struct mt9v011 *core = to_mt9v011(sd);
        unsigned height, width, hblank, vblank, speed;
        unsigned row_time, t_time;
        u64 frames_per_ms;
        unsigned tmp;

        height = mt9v011_read(sd, R03_MT9V011_HEIGHT);
        width = mt9v011_read(sd, R04_MT9V011_WIDTH);
        hblank = mt9v011_read(sd, R05_MT9V011_HBLANK);
        vblank = mt9v011_read(sd, R06_MT9V011_VBLANK);
        speed = mt9v011_read(sd, R0A_MT9V011_CLK_SPEED);

        row_time = (width + 113 + hblank) * (speed + 2);
        t_time = row_time * (height + vblank + 1);

        frames_per_ms = core->xtal * 1000l;
        do_div(frames_per_ms, t_time);
        tmp = frames_per_ms;

        v4l2_dbg(1, debug, sd, "rogrammed to %u.%03u fps (%d pixel clcks)\n",
                tmp / 1000, tmp % 1000, t_time);

        if (numerator && denominator) {
                *numerator = 1000;
                *denominator = (u32)frames_per_ms;
        }
}

static u16 calc_speed(struct v4l2_subdev *sd, u32 numerator, u32 denominator)
{
        struct mt9v011 *core = to_mt9v011(sd);
        unsigned height, width, hblank, vblank;
        unsigned row_time, line_time;
        u64 t_time, speed;

        /* Avoid bogus calculus */
        if (!numerator || !denominator)
                return 0;

        height = mt9v011_read(sd, R03_MT9V011_HEIGHT);
        width = mt9v011_read(sd, R04_MT9V011_WIDTH);
        hblank = mt9v011_read(sd, R05_MT9V011_HBLANK);
        vblank = mt9v011_read(sd, R06_MT9V011_VBLANK);

        row_time = width + 113 + hblank;
        line_time = height + vblank + 1;

        t_time = core->xtal * ((u64)numerator);
        /* round to the closest value */
        t_time += denominator / 2;
        do_div(t_time, denominator);

        speed = t_time;
        do_div(speed, row_time * line_time);

        /* Avoid having a negative value for speed */
        if (speed < 2)
                speed = 0;
        else
                speed -= 2;

        /* Avoid speed overflow */
        if (speed > 15)
                return 15;

        return (u16)speed;
}

static void set_res(struct v4l2_subdev *sd)
{
        struct mt9v011 *core = to_mt9v011(sd);
        unsigned vstart, hstart;

        /*
         * The mt9v011 doesn't have scaling. So, in order to select the desired
         * resolution, we're cropping at the middle of the sensor.
         * hblank and vblank should be adjusted, in order to warrant that
         * we'll preserve the line timings for 30 fps, no matter what resolution
         * is selected.
         * NOTE: datasheet says that width (and height) should be filled with
         * width-1. However, this doesn't work, since one pixel per line will
         * be missing.
         */

        hstart = 14 + (640 - core->width) / 2;
        mt9v011_write(sd, R02_MT9V011_COLSTART, hstart);
        mt9v011_write(sd, R04_MT9V011_WIDTH, core->width);
        mt9v011_write(sd, R05_MT9V011_HBLANK, 771 - core->width);

        vstart = 8 + (480 - core->height) / 2;
        mt9v011_write(sd, R01_MT9V011_ROWSTART, vstart);
        mt9v011_write(sd, R03_MT9V011_HEIGHT, core->height);
        mt9v011_write(sd, R06_MT9V011_VBLANK, 508 - core->height);

        calc_fps(sd, NULL, NULL);
};

static void set_read_mode(struct v4l2_subdev *sd)
{
        struct mt9v011 *core = to_mt9v011(sd);
        unsigned mode = 0x1000;

        if (core->hflip)
                mode |= 0x4000;

        if (core->vflip)
                mode |= 0x8000;

        mt9v011_write(sd, R20_MT9V011_READ_MODE, mode);
}

static int mt9v011_reset(struct v4l2_subdev *sd, u32 val)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(mt9v011_init_default); i++)
                mt9v011_write(sd, mt9v011_init_default.reg,
                               mt9v011_init_default.value);

        set_balance(sd);
        set_res(sd);
        set_read_mode(sd);

        return 0;
};

static int mt9v011_g_ctrl(struct v4l2_subdev *sd, struct v4l2_control *ctrl)
{
        struct mt9v011 *core = to_mt9v011(sd);

        v4l2_dbg(1, debug, sd, "g_ctrl called\n";

        switch (ctrl->id) {
        case V4L2_CID_GAIN:
                ctrl->value = core->global_gain;
                return 0;
        case V4L2_CID_RED_BALANCE:
                ctrl->value = core->red_bal;
                return 0;
        case V4L2_CID_BLUE_BALANCE:
                ctrl->value = core->blue_bal;
                return 0;
        case V4L2_CID_HFLIP:
                ctrl->value = core->hflip ? 1 : 0;
                return 0;
        case V4L2_CID_VFLIP:
                ctrl->value = core->vflip ? 1 : 0;
                return 0;
        }
        return -EINVAL;
}

static int mt9v011_queryctrl(struct v4l2_subdev *sd, struct v4l2_queryctrl *qc)
{
        int i;

        v4l2_dbg(1, debug, sd, "queryctrl called\n";

        for (i = 0; i < ARRAY_SIZE(mt9v011_qctrl); i++)
                if (qc->id && qc->id == mt9v011_qctrl.id) {
                        memcpy(qc, &(mt9v011_qctrl),
                               sizeof(*qc));
                        return 0;
                }

        return -EINVAL;
}

static int mt9v011_s_ctrl(struct v4l2_subdev *sd, struct v4l2_control *ctrl)
{
        struct mt9v011 *core = to_mt9v011(sd);
        u8 i, n;
        n = ARRAY_SIZE(mt9v011_qctrl);

        for (i = 0; i < n; i++) {
                if (ctrl->id != mt9v011_qctrl.id)
                        continue;
                if (ctrl->value < mt9v011_qctrl.minimum ||
                    ctrl->value > mt9v011_qctrl.maximum)
                        return -ERANGE;
                v4l2_dbg(1, debug, sd, "s_ctrl: id=%d, value=%d\n",
                                        ctrl->id, ctrl->value);
                break;
        }

        switch (ctrl->id) {
        case V4L2_CID_GAIN:
                core->global_gain = ctrl->value;
                break;
        case V4L2_CID_RED_BALANCE:
                core->red_bal = ctrl->value;
                break;
        case V4L2_CID_BLUE_BALANCE:
                core->blue_bal = ctrl->value;
                break;
        case V4L2_CID_HFLIP:
                core->hflip = ctrl->value;
                set_read_mode(sd);
                return 0;
        case V4L2_CID_VFLIP:
                core->vflip = ctrl->value;
                set_read_mode(sd);
                return 0;
        default:
                return -EINVAL;
        }

        set_balance(sd);

        return 0;
}

static int mt9v011_enum_fmt(struct v4l2_subdev *sd, struct v4l2_fmtdesc *fmt)
{
        if (fmt->index > 0)
                return -EINVAL;

        fmt->flags = 0;
        strcpy(fmt->description, "8 bpp Bayer GRGR..BGBG";
        fmt->pixelformat = V4L2_PIX_FMT_SGRBG8;

        return 0;
}

static int mt9v011_try_fmt(struct v4l2_subdev *sd, struct v4l2_format *fmt)
{
        struct v4l2_pix_format *pix = &fmt->fmt.pix;

        if (pix->pixelformat != V4L2_PIX_FMT_SGRBG
                return -EINVAL;

        v4l_bound_align_image(&pix->width, 48, 639, 1,
                              &pix->height, 32, 480, 1, 0);

        return 0;
}

static int mt9v011_g_parm(struct v4l2_subdev *sd, struct v4l2_streamparm *parms)
{
        struct v4l2_captureparm *cp = &parms->parm.capture;

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

        memset(cp, 0, sizeof(struct v4l2_captureparm));
        cp->capability = V4L2_CAP_TIMEPERFRAME;
        calc_fps(sd,
                 &cp->timeperframe.numerator,
                 &cp->timeperframe.denominator);

        return 0;
}

static int mt9v011_s_parm(struct v4l2_subdev *sd, struct v4l2_streamparm *parms)
{
        struct v4l2_captureparm *cp = &parms->parm.capture;
        struct v4l2_fract *tpf = &cp->timeperframe;
        u16 speed;

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

        speed = calc_speed(sd, tpf->numerator, tpf->denominator);

        mt9v011_write(sd, R0A_MT9V011_CLK_SPEED, speed);
        v4l2_dbg(1, debug, sd, "Setting speed to %d\n", speed);

        /* Recalculate and update fps info */
        calc_fps(sd, &tpf->numerator, &tpf->denominator);

        return 0;
}

static int mt9v011_s_fmt(struct v4l2_subdev *sd, struct v4l2_format *fmt)
{
        struct v4l2_pix_format *pix = &fmt->fmt.pix;
        struct mt9v011 *core = to_mt9v011(sd);
        int rc;

        rc = mt9v011_try_fmt(sd, fmt);
        if (rc < 0)
                return -EINVAL;

        core->width = pix->width;
        core->height = pix->height;

        set_res(sd);

        return 0;
}

static int mt9v011_s_config(struct v4l2_subdev *sd, int dumb, void *data)
{
        struct mt9v011 *core = to_mt9v011(sd);
        unsigned *xtal = data;

        v4l2_dbg(1, debug, sd, "s_config called\n";

        if (xtal) {
                core->xtal = *xtal;
                v4l2_dbg(1, debug, sd, "xtal set to %d.%03d MHz\n",
                         *xtal / 1000000, (*xtal / 1000) % 1000);
        }

        return 0;
}

#ifdef CONFIG_VIDEO_ADV_DEBUG
static int mt9v011_g_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, ®->match))
                return -EINVAL;
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        reg->val = mt9v011_read(sd, reg->reg & 0xff);
        reg->size = 2;

        return 0;
}

static int mt9v011_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, ®->match))
                return -EINVAL;
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        mt9v011_write(sd, reg->reg & 0xff, reg->val & 0xffff);

        return 0;
}
#endif

static int mt9v011_g_chip_ident(struct v4l2_subdev *sd,
                                struct v4l2_dbg_chip_ident *chip)
{
        u16 version;
        struct i2c_client *client = v4l2_get_subdevdata(sd);

        version = mt9v011_read(sd, R00_MT9V011_CHIP_VERSION);

        return v4l2_chip_ident_i2c_client(client, chip, V4L2_IDENT_MT9V011,
                                          version);
}

static const struct v4l2_subdev_core_ops mt9v011_core_ops = {
        .queryctrl = mt9v011_queryctrl,
        .g_ctrl = mt9v011_g_ctrl,
        .s_ctrl = mt9v011_s_ctrl,
        .reset = mt9v011_reset,
        .s_config = mt9v011_s_config,
        .g_chip_ident = mt9v011_g_chip_ident,
#ifdef CONFIG_VIDEO_ADV_DEBUG
        .g_register = mt9v011_g_register,
        .s_register = mt9v011_s_register,
#endif
};

static const struct v4l2_subdev_video_ops mt9v011_video_ops = {
        .enum_fmt = mt9v011_enum_fmt,
        .try_fmt = mt9v011_try_fmt,
        .s_fmt = mt9v011_s_fmt,
        .g_parm = mt9v011_g_parm,
        .s_parm = mt9v011_s_parm,
};

static const struct v4l2_subdev_ops mt9v011_ops = {
        .core  = &mt9v011_core_ops,
        .video = &mt9v011_video_ops,
};

/****************************************************************************
                        I2C Client & Driver
****************************************************************************/

static int mt9v011_probe(struct i2c_client *c,
                         const struct i2c_device_id *id)
{
        u16 version;
        struct mt9v011 *core;
        struct v4l2_subdev *sd;

        /* Check if the adapter supports the needed features */
        if (!i2c_check_functionality(c->adapter,
             I2C_FUNC_SMBUS_READ_BYTE | I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
                return -EIO;

        core = kzalloc(sizeof(struct mt9v011), GFP_KERNEL);
        if (!core)
                return -ENOMEM;

        sd = &core->sd;
        v4l2_i2c_subdev_init(sd, c, &mt9v011_ops);

        /* Check if the sensor is really a MT9V011 */
        version = mt9v011_read(sd, R00_MT9V011_CHIP_VERSION);
        if ((version != MT9V011_VERSION) &&
            (version != MT9V011_REV_B_VERSION)) {
                v4l2_info(sd, "*** unknown micron chip detected (0x%04x).\n",
                          version);
                kfree(core);
                return -EINVAL;
        }

        core->global_gain = 0x0024;
        core->width  = 640;
        core->height = 480;
        core->xtal = 27000000;        /* Hz */

        v4l_info(c, "chip found @ 0x%02x (%s - chip version 0x%04x)\n",
                 c->addr << 1, c->adapter->name, version);

        return 0;
}

static int mt9v011_remove(struct i2c_client *c)
{
        struct v4l2_subdev *sd = i2c_get_clientdata(c);

        v4l2_dbg(1, debug, sd,
                "mt9v011.c: removing mt9v011 adapter on address 0x%x\n",
                c->addr << 1);

        v4l2_device_unregister_subdev(sd);
        kfree(to_mt9v011(sd));
        return 0;
}

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

static const struct i2c_device_id mt9v011_id[] = {
        { "mt9v011", 0 },
        { }
};
MODULE_DEVICE_TABLE(i2c, mt9v011_id);

static struct v4l2_i2c_driver_data v4l2_i2c_data = {
        .name = "mt9v011",
        .probe = mt9v011_probe,
        .remove = mt9v011_remove,
        .id_table = mt9v011_id,
};