[PATCH v3 1/3] dt-bindings: i2c: Add RTL9300 I2C controller

[Chris Packham <chris.packham@alliedtelesis.co.nz>]

Add dtschema for the I2C controller on the RTL9300 SoC. The I2C
controllers on this SoC are part of the "switch" block which is
represented here as a syscon node. The SCL pins are dependent on the I2C
controller (GPIO8 for the first controller, GPIO 17 for the second). The
SDA pins can be assigned to either one of the I2C controllers (but not
both).

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---

Notes:
    Changes in v3:
    - Remove parent node in example
    - put unevaluatedProperties after required
    - Add #address-cells and #size-cells
    
    Changes in v2:
    - Use reg property for controller registers
    - Remove global-control-offset (will be hard coded in driver)
    - Integrated the multiplexing function. Child nodes now represent the
      available SDA lines

 .../bindings/i2c/realtek,rtl9300-i2c.yaml     | 80 +++++++++++++++++++
 MAINTAINERS                                   |  6 ++
 2 files changed, 86 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/realtek,rtl9300-i2c.yaml

diff --git a/Documentation/devicetree/bindings/i2c/realtek,rtl9300-i2c.yaml b/Documentation/devicetree/bindings/i2c/realtek,rtl9300-i2c.yaml
new file mode 100644
index 000000000000..979ec22e81f1
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/realtek,rtl9300-i2c.yaml
@@ -0,0 +1,80 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/i2c/realtek,rtl9300-i2c.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Realtek RTL I2C Controller
+
+maintainers:
+  - Chris Packham <chris.packham@alliedtelesis.co.nz>
+
+description:
+  The RTL9300 SoC has two I2C controllers. Each of these has an SCL line (which
+  if not-used for SCL can be a GPIO). There are 8 common SDA lines that can be
+  assigned to either I2C controller.
+
+properties:
+  compatible:
+    const: realtek,rtl9300-i2c
+
+  reg:
+    description: Register offset and size this I2C controller.
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+patternProperties:
+  '^i2c@[0-7]$':
+    $ref: /schemas/i2c/i2c-controller.yaml
+    unevaluatedProperties: false
+
+    properties:
+      reg:
+        description: The SDA pin associated with the I2C bus.
+        maxItems: 1
+
+    required:
+      - reg
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    i2c@36c {
+      compatible = "realtek,rtl9300-i2c";
+      reg = <0x36c 0x14>;
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      i2c@0 {
+        reg = <0>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+        gpio@20 {
+          compatible = "nxp,pca9555";
+          gpio-controller;
+          #gpio-cells = <2>;
+          reg = <0x20>;
+        };
+      };
+
+      i2c@2 {
+        reg = <2>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+        gpio@20 {
+          compatible = "nxp,pca9555";
+          gpio-controller;
+          #gpio-cells = <2>;
+          reg = <0x20>;
+        };
+      };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index f328373463b0..ccb1125444f4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19887,6 +19887,12 @@ S:	Maintained
 T:	git https://github.com/pkshih/rtw.git
 F:	drivers/net/wireless/realtek/rtl8xxxu/
 
+RTL9300 I2C DRIVER (rtl9300-i2c)
+M:	Chris Packham <chris.packham@alliedtelesis.co.nz>
+L:	linux-i2c@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/i2c/realtek,rtl9300-i2c.yaml
+
 RTRS TRANSPORT DRIVERS
 M:	Md. Haris Iqbal <haris.iqbal@ionos.com>
 M:	Jack Wang <jinpu.wang@ionos.com>
-- 
2.46.1