dt-bindings: soc: imx8m: add DT Binding doc for soc unique ID

Add DT Binding doc for the Unique ID of i.MX 8M series.

Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alice Guo <alice.guo@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Documentation/devicetree/bindings/soc/imx/imx8m-soc.yaml

@@ -0,0 +1,86 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soc/imx/imx8m-soc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NXP i.MX8M Series SoC
+
+maintainers:
+  - Alice Guo <alice.guo@nxp.com>
+
+description: |
+  NXP i.MX8M series SoCs contain fuse entries from which SoC Unique ID can be
+  obtained.
+
+select:
+  properties:
+    compatible:
+      contains:
+        enum:
+          - fsl,imx8mm
+          - fsl,imx8mn
+          - fsl,imx8mp
+          - fsl,imx8mq
+  required:
+    - compatible
+
+patternProperties:
+  "^soc@[0-9a-f]+$":
+    type: object
+    properties:
+      compatible:
+        items:
+          - enum:
+              - fsl,imx8mm-soc
+              - fsl,imx8mn-soc
+              - fsl,imx8mp-soc
+              - fsl,imx8mq-soc
+          - const: simple-bus
+
+      "#address-cells":
+        const: 1
+
+      "#size-cells":
+        const: 1
+
+      ranges: true
+
+      dma-ranges: true
+
+      nvmem-cells:
+        maxItems: 1
+        description: Phandle to the SOC Unique ID provided by a nvmem node
+
+      nvmem-cell-names:
+        const: soc_unique_id
+
+    required:
+      - compatible
+      - nvmem-cells
+      - nvmem-cell-names
+
+    additionalProperties:
+      type: object
+
+additionalProperties: true
+
+examples:
+  - |
+    / {
+        model = "FSL i.MX8MM EVK board";
+        compatible = "fsl,imx8mm-evk", "fsl,imx8mm";
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        soc@0 {
+            compatible = "fsl,imx8mm-soc", "simple-bus";
+            #address-cells = <1>;
+            #size-cells = <1>;
+            ranges = <0x0 0x0 0x0 0x3e000000>;
+            nvmem-cells = <&imx8mm_uid>;
+            nvmem-cell-names = "soc_unique_id";
+        };
+    };
+
+...