media: rcar-csi2: add Renesas R-Car MIPI CSI-2 receiver driver

A V4L2 driver for Renesas R-Car MIPI CSI-2 receiver. The driver
supports the R-Car Gen3 SoCs where separate CSI-2 hardware blocks are
connected between the video sources and the video grabbers (VIN).

Driver is based on a prototype by Koji Matsuoka in the Renesas BSP.
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/rcar-vin/Kconfig

+config VIDEO_RCAR_CSI2
+	tristate "R-Car MIPI CSI-2 Receiver"
+	depends on VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API && OF
+	depends on ARCH_RENESAS || COMPILE_TEST
+	select V4L2_FWNODE
+	help
+	  Support for Renesas R-Car MIPI CSI-2 receiver.
+	  Supports R-Car Gen3 SoCs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called rcar-csi2.
+
 config VIDEO_RCAR_VIN
 	tristate "R-Car Video Input (VIN) Driver"
 	depends on VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API && OF && HAS_DMA && MEDIA_CONTROLLER

drivers/media/platform/rcar-vin/Makefile

 rcar-vin-objs = rcar-core.o rcar-dma.o rcar-v4l2.o
 
+obj-$(CONFIG_VIDEO_RCAR_CSI2) += rcar-csi2.o
 obj-$(CONFIG_VIDEO_RCAR_VIN) += rcar-vin.o