how "extra-controls" of v4l2src property works

I have to pass exposure time using gstreamer pipeline.
After some online reading i found that we can send it using "extra-controls" property of v4l2src.
How this property mapped with V4L2_CID_PRIVATE_BASE or how to map this property with any v4l2 camera driver.
If i want configurable property in camera driver using gstreamer pipeline then how to achieve that?