dt-bindings: display: mediatek: padding: Add MT8188

Padding is a new hardware module on MediaTek MT8188,
add dt-bindings for it.
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Documentation/devicetree/bindings/display/mediatek/mediatek,padding.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/mediatek/mediatek,padding.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: MediaTek Display Padding
+
+maintainers:
+  - Chun-Kuang Hu <chunkuang.hu@kernel.org>
+  - Philipp Zabel <p.zabel@pengutronix.de>
+
+description:
+  Padding provides ability to add pixels to width and height of a layer with
+  specified colors. Due to hardware design, Mixer in VDOSYS1 requires
+  width of a layer to be 2-pixel-align, or 4-pixel-align when ETHDR is enabled,
+  we need Padding to deal with odd width.
+  Please notice that even if the Padding is in bypass mode, settings in
+  register must be cleared to 0, or undefined behaviors could happen.
+
+properties:
+  compatible:
+    const: mediatek,mt8188-disp-padding
+
+  reg:
+    maxItems: 1
+
+  power-domains:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: Padding's clocks
+
+  mediatek,gce-client-reg:
+    description:
+      GCE (Global Command Engine) is a multi-core micro processor that helps
+      its clients to execute commands without interrupting CPU. This property
+      describes GCE client's information that is composed by 4 fields.
+      1. Phandle of the GCE (there may be several GCE processors)
+      2. Sub-system ID defined in the dt-binding like a user ID
+         (Please refer to include/dt-bindings/gce/<chip>-gce.h)
+      3. Offset from base address of the subsys you are at
+      4. Size of the register the client needs
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    items:
+      items:
+        - description: Phandle of the GCE
+        - description: Subsys ID defined in the dt-binding
+        - description: Offset from base address of the subsys
+        - description: Size of register
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - power-domains
+  - clocks
+  - mediatek,gce-client-reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/clock/mediatek,mt8188-clk.h>
+    #include <dt-bindings/power/mediatek,mt8188-power.h>
+    #include <dt-bindings/gce/mt8195-gce.h>
+
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        padding0: padding@1c11d000 {
+            compatible = "mediatek,mt8188-disp-padding";
+            reg = <0 0x1c11d000 0 0x1000>;
+            clocks = <&vdosys1 CLK_VDO1_PADDING0>;
+            power-domains = <&spm MT8188_POWER_DOMAIN_VDOSYS1>;
+            mediatek,gce-client-reg = <&gce0 SUBSYS_1c11XXXX 0xd000 0x1000>;
+        };
+    };