此节是韦东山第三期学习资料
当插入一个网上买的UVC时，内核UVC驱动会打印出下面的Log信息出来
对应的UVC驱动位于：/drivers/media/usb/uvc
当插入的UVC与uvc_ids匹配了，就会调用uvc_probe函数枚举设备
struct uvc_driver uvc_driver = {
.driver = {
.name = "uvcvideo",
.probe = uvc_probe,
.disconnect = uvc_disconnect,
.suspend = uvc_suspend,
.resume = uvc_resume,
.reset_resume = uvc_reset_resume,
.id_table = uvc_ids,
.supports_autosuspend = 1,
},
};
在uvc_probe函数中，
uvc_probe
->v4l2_device_register
->uvc_register_chains
->uvc_register_terms
->uuv_register_video
->video_register_device // 注册video_device，video_device使用cdev方式注册，cdev_ops = v4l2_fops
虚拟视频驱动vivid.c分析：
1、分配video_device
2、设置video_device结构体
3、注册video_device结构体
代码位置：linux/drivers/platform/vivid
vivid-core.c
static const struct v4l2_file_operations vivid_fops = {
.owner = THIS_MODULE,
.open = v4l2_fh_open,
.release = vivid_fop_release,
.read = vb2_fop_read,
.write = vb2_fop_write,
.poll = vb2_fop_poll,
.unlocked_ioctl = video_ioctl2,
.mmap = vb2_fop_mmap,
};
static const struct v4l2_file_operations vivid_radio_fops = {
.owner = THIS_MODULE,
.open = v4l2_fh_open,
.release = vivid_fop_release,
.read = vivid_radio_read,
.write = vivid_radio_write,
.poll = vivid_radio_poll,
.unlocked_ioctl = video_ioctl2,
};
static const struct v4l2_ioctl_ops vivid_ioctl_ops = {
.vidioc_querycap = vidioc_querycap,
.vidioc_enum_fmt_vid_cap = vidioc_enum_fmt_vid,
.vidioc_g_fmt_vid_cap = vidioc_g_fmt_vid_cap,
.vidioc_try_fmt_vid_cap = vidioc_try_fmt_vid_cap,
.vidioc_s_fmt_vid_cap = vidioc_s_fmt_vid_cap,
.vidioc_enum_fmt_vid_cap_mplane = vidioc_enum_fmt_vid_mplane,
.vidioc_g_fmt_vid_cap_mplane = vidioc_g_fmt_vid_cap_mplane,
.vidioc_try_fmt_vid_cap_mplane = vidioc_try_fmt_vid_cap_mplane,
.vidioc_s_fmt_vid_cap_mplane = vidioc_s_fmt_vid_cap_mplane,
.vidioc_enum_fmt_vid_out = vidioc_enum_fmt_vid,
.vidioc_g_fmt_vid_out = vidioc_g_fmt_vid_out,
.vidioc_try_fmt_vid_out = vidioc_try_fmt_vid_out,
.vidioc_s_fmt_vid_out = vidioc_s_fmt_vid_out,
.vidioc_enum_fmt_vid_out_mplane = vidioc_enum_fmt_vid_mplane,
.vidioc_g_fmt_vid_out_mplane = vidioc_g_fmt_vid_out_mplane,
.vidioc_try_fmt_vid_out_mplane = vidioc_try_fmt_vid_out_mplane,
.vidioc_s_fmt_vid_out_mplane = vidioc_s_fmt_vid_out_mplane,
.vidioc_g_selection = vidioc_g_selection,
.vidioc_s_selection = vidioc_s_selection,
.vidioc_cropcap = vidioc_cropcap,
.vidioc_g_fmt_vbi_cap = vidioc_g_fmt_vbi_cap,
.vidioc_try_fmt_vbi_cap = vidioc_g_fmt_vbi_cap,
.vidioc_s_fmt_vbi_cap = vidioc_s_fmt_vbi_cap,
.vidioc_g_fmt_sliced_vbi_cap = vidioc_g_fmt_sliced_vbi_cap,
.vidioc_try_fmt_sliced_vbi_cap = vidioc_try_fmt_sliced_vbi_cap,
.vidioc_s_fmt_sliced_vbi_cap = vidioc_s_fmt_sliced_vbi_cap,
.vidioc_g_sliced_vbi_cap = vidioc_g_sliced_vbi_cap,
.vidioc_g_fmt_vbi_out = vidioc_g_fmt_vbi_out,
.vidioc_try_fmt_vbi_out = vidioc_g_fmt_vbi_out,
.vidioc_s_fmt_vbi_out = vidioc_s_fmt_vbi_out,
.vidioc_g_fmt_sliced_vbi_out = vidioc_g_fmt_sliced_vbi_out,
.vidioc_try_fmt_sliced_vbi_out = vidioc_try_fmt_sliced_vbi_out,
.vidioc_s_fmt_sliced_vbi_out = vidioc_s_fmt_sliced_vbi_out,
.vidioc_enum_fmt_sdr_cap = vidioc_enum_fmt_sdr_cap,
.vidioc_g_fmt_sdr_cap = vidioc_g_fmt_sdr_cap,
.vidioc_try_fmt_sdr_cap = vidioc_g_fmt_sdr_cap,
.vidioc_s_fmt_sdr_cap = vidioc_g_fmt_sdr_cap,
.vidioc_overlay = vidioc_overlay,
.vidioc_enum_framesizes = vidioc_enum_framesizes,
.vidioc_enum_frameintervals = vidioc_enum_frameintervals,
.vidioc_g_parm = vidioc_g_parm,
.vidioc_s_parm = vidioc_s_parm,
.vidioc_enum_fmt_vid_overlay = vidioc_enum_fmt_vid_overlay,
.vidioc_g_fmt_vid_overlay = vidioc_g_fmt_vid_overlay,
.vidioc_try_fmt_vid_overlay = vidioc_try_fmt_vid_overlay,
.vidioc_s_fmt_vid_overlay = vidioc_s_fmt_vid_overlay,
.vidioc_g_fmt_vid_out_overlay = vidioc_g_fmt_vid_out_overlay,
.vidioc_try_fmt_vid_out_overlay = vidioc_try_fmt_vid_out_overlay,
.vidioc_s_fmt_vid_out_overlay = vidioc_s_fmt_vid_out_overlay,
.vidioc_g_fbuf = vidioc_g_fbuf,
.vidioc_s_fbuf = vidioc_s_fbuf,
.vidioc_reqbufs = vb2_ioctl_reqbufs,
.vidioc_create_bufs = vb2_ioctl_create_bufs,
.vidioc_prepare_buf = vb2_ioctl_prepare_buf,
.vidioc_querybuf = vb2_ioctl_querybuf,
.vidioc_qbuf = vb2_ioctl_qbuf,
.vidioc_dqbuf = vb2_ioctl_dqbuf,
.vidioc_expbuf = vb2_ioctl_expbuf,
.vidioc_streamon = vb2_ioctl_streamon,
.vidioc_streamoff = vb2_ioctl_streamoff,
.vidioc_enum_input = vidioc_enum_input,
.vidioc_g_input = vidioc_g_input,
.vidioc_s_input = vidioc_s_input,
.vidioc_s_audio = vidioc_s_audio,
.vidioc_g_audio = vidioc_g_audio,
.vidioc_enumaudio = vidioc_enumaudio,
.vidioc_s_frequency = vidioc_s_frequency,
.vidioc_g_frequency = vidioc_g_frequency,
.vidioc_s_tuner = vidioc_s_tuner,
.vidioc_g_tuner = vidioc_g_tuner,
.vidioc_s_modulator = vidioc_s_modulator,
.vidioc_g_modulator = vidioc_g_modulator,
.vidioc_s_hw_freq_seek = vidioc_s_hw_freq_seek,
.vidioc_enum_freq_bands = vidioc_enum_freq_bands,
.vidioc_enum_output = vidioc_enum_output,
.vidioc_g_output = vidioc_g_output,
.vidioc_s_output = vidioc_s_output,
.vidioc_s_audout = vidioc_s_audout,
.vidioc_g_audout = vidioc_g_audout,
.vidioc_enumaudout = vidioc_enumaudout,
.vidioc_querystd = vidioc_querystd,
.vidioc_g_std = vidioc_g_std,
.vidioc_s_std = vidioc_s_std,
.vidioc_s_dv_timings = vidioc_s_dv_timings,
.vidioc_g_dv_timings = vidioc_g_dv_timings,
.vidioc_query_dv_timings = vidioc_query_dv_timings,
.vidioc_enum_dv_timings = vidioc_enum_dv_timings,
.vidioc_dv_timings_cap = vidioc_dv_timings_cap,
.vidioc_g_edid = vidioc_g_edid,
.vidioc_s_edid = vidioc_s_edid,
.vidioc_log_status = v4l2_ctrl_log_status,
.vidioc_subscribe_event = vidioc_subscribe_event,
.vidioc_unsubscribe_event = v4l2_event_unsubscribe,
};
vivid_init
->vivid_probe
->vivid_create_instance
->设置ctrl（用于app的ioctl）：事先添加属性
例如dev->brightness = v4l2_ctrl_new_std(hdl_user_vid, &vivid_user_vid_ctrl_ops,
V4L2_CID_BRIGHTNESS, 0, 255, 1, 128);
->v4l2_device_register // 不是主要，主要初始化一些东西，比如自旋锁，引用计数
->video_register_device(vfd, VFL_TYPE_GRABBER, vid_cap_nr[inst]); // 根据不同的功能，实现不同的节点注册
->__video_register_device
vdev->cdev = cdev_alloc();
vdev->cdev->ops = &v4l2_fops;
cdev_add
分析vivid的open、read、write、ioctl过程：
app: open("/dev/video0",...)
--------------------------------------------------------------------------------
drv: v4l2_open
vdev = video_devdata(filp); // 根据次设备号从数组中得到video_device
ret = vdev->fops->open(filp); // 也就是vivid_fops->v4l2_fh_open函数
app: ioctl
--------------------------------------------------------------------------------
drv: v4l2_fops.unlocked_ioctl
v4l2-ioctl
struct video_device vdev = video_devdata(filp);
ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
video_ioctl2
video_usercopy(file, cmd, arg, __video_do_ioctl);
__video_do_ioctl
struct video_device *vfd = video_devdata(file);
根据app传入的cmn来获取设置某些属性
如何填写v4l2驱动： 1、分配设置注册v4l2_device：v4l2_device_register，得到v4l2_device（辅助作用，提供自旋锁引用计数） 2、分配设置注册一个video_device结构体，video_register_device，video_device.v4l2_device指向第一步分配的v4l2_device 3、video_device.v4l2_file_operations会被上层应用调用到的open/read/ioctl所调用 4、video_device.v4l2_ioctl_ops会被上层应用调用到的ioctl所间接调用 5、app可以通过ioctl来设置亮度等等信息，驱动程序使用v4l2_ctrl属性来表示接收存储设置到硬件 属性：v4l2_ctrl 管理：v4l2_ctrl_handler 初始化一个v4l2_ctrl_hander：v4l2_ctrl_handler_init 添加v4l2_ctrl属性项：v4l2_ctrl_new_std和v4l2_ctrl_new_custom，创建个个v4l2_ctrl，放入v4l2_ctrl_handler管理的链表 6、v4l2_dev.ctrl_handler和video_dev->v4l2_dev相关联
v4l2_vtrl_handler的使用过程：
IOCTL_INFO_FNC(VIDIOC_QUERYCTRL, v4l_queryctrl, v4l_print_queryctrl, INFO_FL_CTRL | INFO_FL _CLEAR(v4l2_queryctrl, id)),
->
static int v4l_queryctrl(const struct v4l2_ioctl_ops *ops,
struct file *file, void *fh, void *arg)
{
struct video_device *vfd = video_devdata(file);
struct v4l2_queryctrl *p = arg;
struct v4l2_fh *vfh =
test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) ? fh : NULL;
if (vfh && vfh->ctrl_handler)
return v4l2_queryctrl(vfh->ctrl_handler, p);
if (vfd->ctrl_handler)
return v4l2_queryctrl(vfd->ctrl_handler, p);
if (ops->vidioc_queryctrl)
return ops->vidioc_queryctrl(file, fh, p);
return -ENOTTY;
}
标签：vid,框架,fmt,cap,vidioc,UVC,v4l2,out From： https://www.cnblogs.com/lethe1203/p/18111343