一、攝像頭平臺層? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ??

drivers\media\video\mxc\capture\mxc_v4l2_capture.c

module_init(camera_init);

隨后，進行加載下一個驅動，如果遇到攝像頭設備層對應驅動，舉例adv7180解碼芯片

drivers\media\video\mxc\capture\adv7180.c

module_init(adv7180_init);

static __init int?adv7180_init(void)
{
?　　u8 err = i2c_add_driver(&adv7180_i2c_driver);

return err;
}

static struct i2c_driver?adv7180_i2c_driver?= {
?　　.driver = {
???? 　　.owner = THIS_MODULE,
???? 　　.name = "adv7180",
???? 　},
?　　.probe = adv7180_probe,
?　　.remove = adv7180_detach,
?　　.id_table =?adv7180_id,
};

static __init int?camera_init(void)
{

u8 err = platform_driver_register(&mxc_v4l2_driver);//將mxc_v4l2_driver這個驅動注冊到platform平臺上面，如果有匹配的設備的話，就會調用到mxc_v4l2_driver里面的probe函數
return err;
}

static struct platform_driver?mxc_v4l2_driver?= {
?　　.driver = {
???? 　　.name = "mxc_v4l2_capture",
???? },
?　　.probe =?mxc_v4l2_probe,
?　　.remove = mxc_v4l2_remove,
?　　.suspend = mxc_v4l2_suspend,
?　　.resume = mxc_v4l2_resume,
?　　.shutdown = NULL,
};

/*

*struct?platform_device?{
?*??const char?* name;
?*??int??id;
?*??struct device?dev;
?*??u32??num_resources;
?*??struct resource?* resource;
?*??const struct platform_device_id?*id_entry;
?*??struct mfd_cell *mfd_cell;
?*??struct pdev_archdata?archdata;
?*};

*/

static int?mxc_v4l2_probe(struct?platform_device?*pdev)

{

...

cam_data *cam = kmalloc(sizeof(cam_data), GFP_KERNEL);

init_camera_struct(cam, pdev);//初始化cam_data結構體

v4l2_int_device_register(cam->self);

...

}

/*私有數據的結構體關系

*struct cam_data???????　　　　drivers\media\video\mxc\capture\mxc_v4l2_capture.h
?*->struct video_device?????　　include\media\v4l2-dev.h?
?*?? ->struct device　　　　　　include\linux\device.h
?*???? ->struct device_private???drivers\base\base.h
?*?????? ->void *driver_data;

*/

static void?init_camera_struct(cam_data *cam, struct platform_device *pdev)

{

...

cam->video_dev = video_device_alloc();//分配一個video_device結構體

*(cam->video_dev) = mxc_v4l_template;//設置ops操作->v4l2_file_operations->mxc_v4l_ioctl->mxc_v4l_do_ioctl->VIDIOC_*_IOCTL:{...}

video_set_drvdata(cam->video_dev, cam);//將cam設置為cam->video_dev的私有數據->dev_set_drvdata ->?dev->p->driver_data = data;

cam->crop_bounds.left = 0;?????　　　　　　//這里只是初始化crop參數默認值

cam->crop_bounds.width = 640;

cam->crop_bounds.top = 0;

cam->crop_bounds.height = 480;

cam->crop_current = cam->crop_defrect = cam->crop_bounds;

cam->enc_callback = camera_callback;

cam->self = kmalloc(sizeof(struct v4l2_int_device), GFP_KERNEL);

cam->self->module = THIS_MODULE;
cam->self->type = v4l2_int_type_master;
cam->self->u.master = &mxc_v4l2_master;//后面會調用

...

}

int?v4l2_int_device_register(struct v4l2_int_device *d)
{
?　　...
v4l2_int_device_try_attach_all();

...
}

void?v4l2_int_device_try_attach_all(void)

{

struct v4l2_int_device *m, *s;

list_for_each_entry(m, &int_list, head)?
{

if (m->type != v4l2_int_type_master) continue;//從int_list鏈表中取出type類型為v4l2_int_type_master的結構體保存在m中

list_for_each_entry(s, &int_list, head)?
{

if (s->type != v4l2_int_type_slave)continue;//從int_list鏈表中取出type類型為v4l2_int_type_slave的結構體保存在s中

if (s->u.slave->master)continue;//如果存在s->u.slave->master則跳過繼續(xù)尋找

s->u.slave->master = m;//找到master設備和第一個沒有設置master的slave設備，并將從設備的master設置為找到的master

if (m->u.master->attach(s))//調用m的u.master->atach(s)函數，即cam->self->u.master = &mxc_v4l2_master;設置的函數

{

...

}

}

}

}

static struct v4l2_int_master?mxc_v4l2_master?= {
.attach =?mxc_v4l2_master_attach,
.detach = mxc_v4l2_master_detach,
};

static int?mxc_v4l2_master_attach(struct v4l2_int_device *slave)

{

...

cam->crop_bounds.top = cam->crop_bounds.left = 0;//crop參數都是根據slave結構體來設置的,這里是根據真正slave設備中獲取到的參數來填充crop參數
?　　cam->crop_bounds.width = cam_fmt.fmt.pix.width;
?　　cam->crop_bounds.height = cam_fmt.fmt.pix.height;

cam->crop_defrect.top = cam->crop_defrect.left = 0;
?cam->crop_defrect.width = cam_fmt.fmt.pix.width;
?　　cam->crop_defrect.height = cam_fmt.fmt.pix.height;

cam->crop_current.top = cam->crop_current.left = 0;
?　　cam->crop_current.width = cam_fmt.fmt.pix.width;
?　　cam->crop_current.height = cam_fmt.fmt.pix.height;

...

}

?