dt-bindings: display: Document Renesas RZ/G2L DU bindings

The RZ/G2L LCD controller is composed of Frame Compression Processor
(FCPVD), Video Signal Processor (VSPD), and Display Unit (DU).

The DU module supports the following hardware features
− Display Parallel Interface (DPI) and MIPI LINK Video Interface
− Display timing master
− Generates video timings
− Selecting the polarity of output DCLK, HSYNC, VSYNC, and DE
− Supports Progressive
− Input data format (from VSPD): RGB888, RGB666
− Output data format: same as Input data format
− Supporting Full HD (1920 pixels x 1080 lines) for MIPI-DSI Output
− Supporting WXGA (1280 pixels x 800 lines) for Parallel Output

This patch documents the DU module found on RZ/G2L LCDC.
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Link: https://lore.kernel.org/r/20240218164840.57662-2-biju.das.jz@bp.renesas.comSigned-off-by: Maxime Ripard <mripard@kernel.org>

Documentation/devicetree/bindings/display/renesas,rzg2l-du.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/renesas,rzg2l-du.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Renesas RZ/G2L Display Unit (DU)
+
+maintainers:
+  - Biju Das <biju.das.jz@bp.renesas.com>
+  - Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
+
+description: |
+  These DT bindings describe the Display Unit embedded in the Renesas RZ/G2L
+  and RZ/V2L SoCs.
+
+properties:
+  compatible:
+    enum:
+      - renesas,r9a07g044-du # RZ/G2{L,LC}
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: Main clock
+      - description: Register access clock
+      - description: Video clock
+
+  clock-names:
+    items:
+      - const: aclk
+      - const: pclk
+      - const: vclk
+
+  resets:
+    maxItems: 1
+
+  power-domains:
+    maxItems: 1
+
+  ports:
+    $ref: /schemas/graph.yaml#/properties/ports
+    description: |
+      The connections to the DU output video ports are modeled using the OF
+      graph bindings. The number of ports and their assignment are
+      model-dependent. Each port shall have a single endpoint.
+
+    patternProperties:
+      "^port@[0-1]$":
+        $ref: /schemas/graph.yaml#/properties/port
+        unevaluatedProperties: false
+
+    required:
+      - port@0
+
+    unevaluatedProperties: false
+
+  renesas,vsps:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    items:
+      items:
+        - description: phandle to VSP instance that serves the DU channel
+        - description: Channel index identifying the LIF instance in that VSP
+    description:
+      A list of phandle and channel index tuples to the VSPs that handle the
+      memory interfaces for the DU channels.
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - clock-names
+  - resets
+  - power-domains
+  - ports
+  - renesas,vsps
+
+additionalProperties: false
+
+examples:
+  # RZ/G2L DU
+  - |
+    #include <dt-bindings/clock/r9a07g044-cpg.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    display@10890000 {
+        compatible = "renesas,r9a07g044-du";
+        reg = <0x10890000 0x10000>;
+        interrupts = <GIC_SPI 152 IRQ_TYPE_LEVEL_HIGH>;
+        clocks = <&cpg CPG_MOD R9A07G044_LCDC_CLK_A>,
+                 <&cpg CPG_MOD R9A07G044_LCDC_CLK_P>,
+                 <&cpg CPG_MOD R9A07G044_LCDC_CLK_D>;
+        clock-names = "aclk", "pclk", "vclk";
+        resets = <&cpg R9A07G044_LCDC_RESET_N>;
+        power-domains = <&cpg>;
+
+        renesas,vsps = <&vspd0 0>;
+
+        ports {
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            port@0 {
+                reg = <0>;
+                endpoint {
+                    remote-endpoint = <&dsi0_in>;
+                };
+            };
+            port@1 {
+                reg = <1>;
+            };
+        };
+    };
+
+...