dt-bindings: i2c: Add Apple I2C controller bindings

The Apple I2C controller is based on the PASemi I2C controller.
It is present on Apple SoCs such as the M1.
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sven Peter <sven@svenpeter.dev>
Acked-by: Olof Johansson <olof@lixom.net>
Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

Documentation/devicetree/bindings/i2c/apple,i2c.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/i2c/apple,i2c.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: Apple/PASemi I2C controller
+
+maintainers:
+  - Sven Peter <sven@svenpeter.dev>
+
+description: |
+  Apple SoCs such as the M1 come with a I2C controller based on the one found
+  in machines with P. A. Semi's PWRficient processors.
+  The bus is used to communicate with e.g. USB PD chips or the speaker
+  amp.
+
+allOf:
+  - $ref: /schemas/i2c/i2c-controller.yaml#
+
+properties:
+  compatible:
+    enum:
+      - apple,t8103-i2c
+      - apple,i2c
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: I2C bus reference clock
+
+  interrupts:
+    maxItems: 1
+
+  clock-frequency:
+    description: |
+      Desired I2C bus clock frequency in Hz. If not specified, 100 kHz will be
+      used. This frequency is generated by dividing the reference clock.
+      Allowed values are between ref_clk/(16*4) and ref_clk/(16*255).
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - interrupts
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    i2c@35010000 {
+      compatible = "apple,t8103-i2c";
+      reg = <0x35010000 0x4000>;
+      interrupt-parent = <&aic>;
+      interrupts = <0 627 4>;
+      clocks = <&ref_clk>;
+      #address-cells = <1>;
+      #size-cells = <0>;
+    };