media: dt-bindings: media: Document bindings for the Cedrus VPU driver

This adds a device-tree binding document that specifies the properties
used by the Cedrus VPU driver, as well as examples.
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/devicetree/bindings/media/cedrus.txt

+Device-tree bindings for the VPU found in Allwinner SoCs, referred to as the
+Video Engine (VE) in Allwinner literature.
+
+The VPU can only access the first 256 MiB of DRAM, that are DMA-mapped starting
+from the DRAM base. This requires specific memory allocation and handling.
+
+Required properties:
+- compatible		: must be one of the following compatibles:
+			- "allwinner,sun4i-a10-video-engine"
+			- "allwinner,sun5i-a13-video-engine"
+			- "allwinner,sun7i-a20-video-engine"
+			- "allwinner,sun8i-a33-video-engine"
+			- "allwinner,sun8i-h3-video-engine"
+- reg			: register base and length of VE;
+- clocks		: list of clock specifiers, corresponding to entries in
+			  the clock-names property;
+- clock-names		: should contain "ahb", "mod" and "ram" entries;
+- resets		: phandle for reset;
+- interrupts		: VE interrupt number;
+- allwinner,sram	: SRAM region to use with the VE.
+
+Optional properties:
+- memory-region		: CMA pool to use for buffers allocation instead of the
+			  default CMA pool.
+
+Example:
+
+reserved-memory {
+	#address-cells = <1>;
+	#size-cells = <1>;
+	ranges;
+
+	/* Address must be kept in the lower 256 MiBs of DRAM for VE. */
+	cma_pool: cma@4a000000 {
+		compatible = "shared-dma-pool";
+		size = <0x6000000>;
+		alloc-ranges = <0x4a000000 0x6000000>;
+		reusable;
+		linux,cma-default;
+	};
+};
+
+video-codec@1c0e000 {
+	compatible = "allwinner,sun7i-a20-video-engine";
+	reg = <0x01c0e000 0x1000>;
+
+	clocks = <&ccu CLK_AHB_VE>, <&ccu CLK_VE>,
+		 <&ccu CLK_DRAM_VE>;
+	clock-names = "ahb", "mod", "ram";
+
+	resets = <&ccu RST_VE>;
+	interrupts = <GIC_SPI 53 IRQ_TYPE_LEVEL_HIGH>;
+	allwinner,sram = <&ve_sram 1>;
+};