dt-bindings: display: add Amlogic Meson DRM Bindings

Amlogic Meson Display Controller

================================

The Amlogic Meson Display controller is composed of several components

that are going to be documented below:

DMC|---------------VPU (Video Processing Unit)----------------|------HHI------|

   | vd1   _______     _____________    _________________     |               |

D  |-------|      |----|            |   |                |    |   HDMI PLL    |

D  | vd2   | VIU  |    | Video Post |   | Video Encoders |<---|-----VCLK      |

R  |-------|      |----| Processing |   |                |    |               |

   | osd2  |      |    |            |---| Enci ----------|----|-----VDAC------|

R  |-------| CSC  |----| Scalers    |   | Encp ----------|----|----HDMI-TX----|

A  | osd1  |      |    | Blenders   |   | Encl ----------|----|---------------|

M  |-------|______|----|____________|   |________________|    |               |

___|__________________________________________________________|_______________|

VIU: Video Input Unit

---------------------

The Video Input Unit is in charge of the pixel scanout from the DDR memory.

It fetches the frames addresses, stride and parameters from the "Canvas" memory.

This part is also in charge of the CSC (Colorspace Conversion).

It can handle 2 OSD Planes and 2 Video Planes.

VPP: Video Post Processing

--------------------------

The Video Post Processing is in charge of the scaling and blending of the

various planes into a single pixel stream.

There is a special "pre-blending" used by the video planes with a dedicated

scaler and a "post-blending" to merge with the OSD Planes.

The OSD planes also have a dedicated scaler for one of the OSD.

VENC: Video Encoders

--------------------

The VENC is composed of the multiple pixel encoders :

 - ENCI : Interlace Video encoder for CVBS and Interlace HDMI

 - ENCP : Progressive Video Encoder for HDMI

 - ENCL : LCD LVDS Encoder

The VENC Unit gets a Pixel Clocks (VCLK) from a dedicated HDMI PLL and clock

tree and provides the scanout clock to the VPP and VIU.

The ENCI is connected to a single VDAC for Composite Output.

The ENCI and ENCP are connected to an on-chip HDMI Transceiver.

Device Tree Bindings:

---------------------

VPU: Video Processing Unit

--------------------------

Required properties:

- compatible: value should be different for each SoC family as :

	- GXBB (S905) : "amlogic,meson-gxbb-vpu"

	- GXL (S905X, S905D) : "amlogic,meson-gxl-vpu"

	- GXM (S912) : "amlogic,meson-gxm-vpu"

	followed by the common "amlogic,meson-gx-vpu"

- reg: base address and size of he following memory-mapped regions :

	- vpu

	- hhi

	- dmc

- reg-names: should contain the names of the previous memory regions

- interrupts: should contain the VENC Vsync interrupt number

Required nodes:

The connections to the VPU output video ports are modeled using the OF graph

bindings specified in Documentation/devicetree/bindings/graph.txt.

The following table lists for each supported model the port number

corresponding to each VPU output.

		Port 0		Port 1

-----------------------------------------

 S905 (GXBB)	CVBS VDAC	HDMI-TX

 S905X (GXL)	CVBS VDAC	HDMI-TX

 S905D (GXL)	CVBS VDAC	HDMI-TX

 S912 (GXM)	CVBS VDAC	HDMI-TX

Example:

tv-connector {

	compatible = "composite-video-connector";

	port {

		tv_connector_in: endpoint {

			remote-endpoint = <&cvbs_vdac_out>;

		};

	};

};

vpu: vpu@d0100000 {

	compatible = "amlogic,meson-gxbb-vpu";

	reg = <0x0 0xd0100000 0x0 0x100000>,

	      <0x0 0xc883c000 0x0 0x1000>,

	      <0x0 0xc8838000 0x0 0x1000>;

	reg-names = "vpu", "hhi", "dmc";

	interrupts = <GIC_SPI 3 IRQ_TYPE_EDGE_RISING>;

	#address-cells = <1>;

	#size-cells = <0>;

	/* CVBS VDAC output port */

	port@0 {

		reg = <0>;

		cvbs_vdac_out: endpoint {

			remote-endpoint = <&tv_connector_in>;

		};

	};

};