dt-bindings: display: imx: add bindings for DCSS

Add bindings for iMX8MQ Display Controller Subsystem.
Signed-off-by: Laurentiu Palcu <laurentiu.palcu@nxp.com>
Reviewed-by: Guido Günther <agx@sigxcpu.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20200731081836.3048-6-laurentiu.palcu@oss.nxp.com

Documentation/devicetree/bindings/display/imx/nxp,imx8mq-dcss.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+# Copyright 2019 NXP
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/display/imx/nxp,imx8mq-dcss.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: iMX8MQ Display Controller Subsystem (DCSS)
+
+maintainers:
+  - Laurentiu Palcu <laurentiu.palcu@nxp.com>
+
+description:
+
+  The DCSS (display controller sub system) is used to source up to three
+  display buffers, compose them, and drive a display using HDMI 2.0a(with HDCP
+  2.2) or MIPI-DSI. The DCSS is intended to support up to 4kp60 displays. HDR10
+  image processing capabilities are included to provide a solution capable of
+  driving next generation high dynamic range displays.
+
+properties:
+  compatible:
+    const: nxp,imx8mq-dcss
+
+  reg:
+    items:
+      - description: DCSS base address and size, up to IRQ steer start
+      - description: DCSS BLKCTL base address and size
+
+  interrupts:
+    items:
+      - description: Context loader completion and error interrupt
+      - description: DTG interrupt used to signal context loader trigger time
+      - description: DTG interrupt for Vblank
+
+  interrupt-names:
+    items:
+      - const: ctxld
+      - const: ctxld_kick
+      - const: vblank
+
+  clocks:
+    items:
+      - description: Display APB clock for all peripheral PIO access interfaces
+      - description: Display AXI clock needed by DPR, Scaler, RTRAM_CTRL
+      - description: RTRAM clock
+      - description: Pixel clock, can be driven either by HDMI phy clock or MIPI
+      - description: DTRC clock, needed by video decompressor
+
+  clock-names:
+    items:
+      - const: apb
+      - const: axi
+      - const: rtrm
+      - const: pix
+      - const: dtrc
+
+  assigned-clocks:
+    items:
+      - description: Phandle and clock specifier of IMX8MQ_CLK_DISP_AXI_ROOT
+      - description: Phandle and clock specifier of IMX8MQ_CLK_DISP_RTRM
+      - description: Phandle and clock specifier of either IMX8MQ_VIDEO2_PLL1_REF_SEL or
+                     IMX8MQ_VIDEO_PLL1_REF_SEL
+
+  assigned-clock-parents:
+    items:
+      - description: Phandle and clock specifier of IMX8MQ_SYS1_PLL_800M
+      - description: Phandle and clock specifier of IMX8MQ_SYS1_PLL_800M
+      - description: Phandle and clock specifier of IMX8MQ_CLK_27M
+
+  assigned-clock-rates:
+    items:
+      - description: Must be 800 MHz
+      - description: Must be 400 MHz
+
+  port:
+    type: object
+    description:
+      A port node pointing to the input port of a HDMI/DP or MIPI display bridge.
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/imx8mq-clock.h>
+    dcss: display-controller@32e00000 {
+        compatible = "nxp,imx8mq-dcss";
+        reg = <0x32e00000 0x2d000>, <0x32e2f000 0x1000>;
+        interrupts = <6>, <8>, <9>;
+        interrupt-names = "ctxld", "ctxld_kick", "vblank";
+        interrupt-parent = <&irqsteer>;
+        clocks = <&clk IMX8MQ_CLK_DISP_APB_ROOT>, <&clk IMX8MQ_CLK_DISP_AXI_ROOT>,
+                 <&clk IMX8MQ_CLK_DISP_RTRM_ROOT>, <&clk IMX8MQ_VIDEO2_PLL_OUT>,
+                 <&clk IMX8MQ_CLK_DISP_DTRC>;
+        clock-names = "apb", "axi", "rtrm", "pix", "dtrc";
+        assigned-clocks = <&clk IMX8MQ_CLK_DISP_AXI>, <&clk IMX8MQ_CLK_DISP_RTRM>,
+                          <&clk IMX8MQ_VIDEO2_PLL1_REF_SEL>;
+        assigned-clock-parents = <&clk IMX8MQ_SYS1_PLL_800M>, <&clk IMX8MQ_SYS1_PLL_800M>,
+                                 <&clk IMX8MQ_CLK_27M>;
+        assigned-clock-rates = <800000000>,
+                               <400000000>;
+        port {
+            dcss_out: endpoint {
+                remote-endpoint = <&hdmi_in>;
+            };
+        };
+    };
+