CSI is a submodule of IVSC which can route camera sensor data
to the outbound MIPI CSI-2 interface.

The interface communicating with firmware is via MEI. There is
a separate MEI UUID, which this driver uses to enumerate.

To route camera sensor data to host, the information of link
frequency and number of data lanes is sent to firmware by
sending MEI command when starting stream.

CSI also provides a privacy mode. When privacy mode is turned
on, camera sensor can't be used. This means that both IVSC and
host Image Processing Unit(IPU) can't get image data. And when
this mode is turned on, user is notified via v4l2 control
callback.

Link: https://lore.kernel.org/linux-media/20230803115550.1601965-2-sakari.ailus@linux.intel.comSigned-off-by: Wentong Wu <wentong.wu@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>