media: staging: media: Add support for the Allwinner A31 ISP

Some Allwinner platforms come with an Image Signal Processor, which
supports various features in order to enhance and transform data
received by image sensors into good-looking pictures. In most cases,
the data is raw bayer, which gets internally converted to RGB and
finally YUV, which is what the hardware produces.

This driver supports ISPs that are similar to the A31 ISP, which was
the first standalone ISP found in Allwinner platforms. Simpler ISP
blocks were found in the A10 and A20, where they are tied to a CSI
controller. Newer generations of Allwinner SoCs (starting with the
H6, H616, etc) come with a new camera subsystem and revised ISP.
Even though these previous and next-generation ISPs are somewhat
similar to the A31 ISP, they have enough significant differences to
be out of the scope of this driver.

While the ISP supports many features, including 3A and many
enhancement blocks, this implementation is limited to the following:
- V3s (V3/S3) platform support;
- Bayer media bus formats as input;
- Semi-planar YUV (NV12/NV21) as output;
- Debayering with per-component gain and offset configuration;
- 2D noise filtering with configurable coefficients.

Since many features are missing from the associated uAPI, the driver
is aimed to integrate staging until all features are properly
described.

On the technical side, it uses the v4l2 and media controller APIs,
with a video node for capture, a processor subdev and a video node
for parameters submission. A specific uAPI structure and associated
v4l2 meta format are used to configure parameters of the supported
modules.

One particular thing about the hardware is that configuration for
module registers needs to be stored in a DMA buffer and gets copied
to actual registers by the hardware at the next vsync, when instructed
by a flag. This is handled by the "state" mechanism in the driver.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

staging: add missing SPDX lines to Kconfig files

There are a few remaining drivers/staging/*/Kconfig files that do not
have SPDX identifiers in them. Add the correct GPL-2.0 identifier to
them to make scanning tools happy.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

media: platform: Add Cedrus VPU decoder driver

This introduces the Cedrus VPU driver that supports the VPU found in
Allwinner SoCs, also known as Video Engine. It is implemented through
a V4L2 M2M decoder device and a media device (used for media requests).
So far, it only supports MPEG-2 decoding.

Since this VPU is stateless, synchronization with media requests is
required in order to ensure consistency between frame headers that
contain metadata about the frame to process and the raw slice data that
is used to generate the frame.

This driver was made possible thanks to the long-standing effort
carried out by the linux-sunxi community in the interest of reverse
engineering, documenting and implementing support for the Allwinner VPU.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
[hans.verkuil@cisco.com: dropped obsolete MEDIA_REQUEST_API from Kconfig]
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>