media: staging: media: omap4iss: Added SPDX license identifiers

Added missing SPDX license identifiers to all files of the omap4iss
driver.

Most files already have license texts which clearly state them to be
licensed under GPL 2.0 or later. SPDX identifiers were added accordingly.

Some files do not have any license text. SPDX identifiers for GPL 2.0
were added to them, in accordance with the default license of the
kernel.

Signed-off-by: Daniel Graefe <daniel.graefe@fau.de>
Signed-off-by: Roman Sommer <roman.sommer@fau.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

[media] v4l: omap4iss: Replace outdated OMAP4 control pad API with syscon

The omap4_ctrl_pad_readl and omap4_ctrl_pad_writel functions have been
removed by commit efde234674d9 but are still used by the OMAP4 ISS
driver, resulting in a compilation breakage:

drivers/staging/media/omap4iss/iss_csiphy.c: In function 'omap4iss_csiphy_config':
drivers/staging/media/omap4iss/iss_csiphy.c:167:2: error: implicit declaration of function 'omap4_ctrl_pad_writel' [-Werror=implicit-function-declaration]
omap4_ctrl_pad_writel(cam_rx_ctrl,

Fix the problem by using the syscon API to reaplace the control pad API.
Lookup the syscon instance by compatible name for now as the OMAP4 ISS
driver doesn't support DT yet.

Fixes: efde234674d9 ("ARM: OMAP4+: control: remove support for legacy pad read/write")

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sakari Alius <sakari.ailus@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

[media] v4l: omap4iss: Convert hexadecimal constants to lower case

The Linux kernel recommends lower case for hexadecimal constants.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

[media] v4l: omap4iss: csi: Create and use register access functions

Replace the direct readl/writel calls with helper functions.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

[media] v4l: omap4iss: csi2: Enable automatic ULP mode transition

Automatically switch between ULP and ON states based on ULPM signal from
complex I/O.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

[media] v4l: omap4iss: Restrict line lengths to 80 characters where possible

Pure CodingStyle fixes.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

[media] v4l: omap4iss: Replace printk by dev_err

dev_err is preferred over printk(KERN_ERR) when a device pointer is
available.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

[media] v4l: omap4iss: Add support for OMAP4 camera interface - CSI receivers

This adds a very simplistic driver to utilize the CSI2A interface inside
the ISS subsystem in OMAP4, and dump the data to memory.
Check Documentation/video4linux/omap4_camera.txt for details.
This commit adds CSI receivers support.

Signed-off-by: Sergio Aguirre <sergio.a.aguirre@gmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>