dt-bindings: i2c: i2c-mux-pinctrl: Convert to json-schema

Convert the pinctrl-based I2C mux bindings from the free-form text
format to json-schema.

Signed-off-by: Thierry Reding <[email protected]>
Signed-off-by: Rob Herring <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.yaml

@@ -0,0 +1,103 @@
+# SPDX-License-Identifier: GPL-2.0-only
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/i2c/i2c-mux-pinctrl.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Pinctrl-based I2C Bus Mux
+
+maintainers:
+  - Wolfram Sang <[email protected]>
+
+description: |
+  This binding describes an I2C bus multiplexer that uses pin multiplexing to route the I2C
+  signals, and represents the pin multiplexing configuration using the pinctrl device tree
+  bindings.
+
+                                 +-----+  +-----+
+                                 | dev |  | dev |
+    +------------------------+   +-----+  +-----+
+    | SoC                    |      |        |
+    |                   /----|------+--------+
+    |   +---+   +------+     | child bus A, on first set of pins
+    |   |I2C|---|Pinmux|     |
+    |   +---+   +------+     | child bus B, on second set of pins
+    |                   \----|------+--------+--------+
+    |                        |      |        |        |
+    +------------------------+  +-----+  +-----+  +-----+
+                                | dev |  | dev |  | dev |
+                                +-----+  +-----+  +-----+
+
+  For each named state defined in the pinctrl-names property, an I2C child bus will be created.
+  I2C child bus numbers are assigned based on the index into the pinctrl-names property.
+
+  The only exception is that no bus will be created for a state named "idle". If such a state is
+  defined, it must be the last entry in pinctrl-names. For example:
+
+    pinctrl-names = "ddc", "pta", "idle"  ->  ddc = bus 0, pta = bus 1
+    pinctrl-names = "ddc", "idle", "pta"  ->  Invalid ("idle" not last)
+    pinctrl-names = "idle", "ddc", "pta"  ->  Invalid ("idle" not last)
+
+  Whenever an access is made to a device on a child bus, the relevant pinctrl state will be
+  programmed into hardware.
+
+  If an idle state is defined, whenever an access is not being made to a device on a child bus,
+  the idle pinctrl state will be programmed into hardware.
+
+  If an idle state is not defined, the most recently used pinctrl state will be left programmed
+  into hardware whenever no access is being made of a device on a child bus.
+
+properties:
+  compatible:
+    const: i2c-mux-pinctrl
+
+  i2c-parent:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description: The phandle of the I2C bus that this multiplexer's master-side port is connected
+      to.
+
+allOf:
+  - $ref: i2c-mux.yaml
+
+unevaluatedProperties: false
+
+required:
+  - compatible
+  - i2c-parent
+
+examples:
+  - |
+    i2cmux {
+      compatible = "i2c-mux-pinctrl";
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      i2c-parent = <&i2c1>;
+
+      pinctrl-names = "ddc", "pta", "idle";
+      pinctrl-0 = <&state_i2cmux_ddc>;
+      pinctrl-1 = <&state_i2cmux_pta>;
+      pinctrl-2 = <&state_i2cmux_idle>;
+
+      i2c@0 {
+        reg = <0>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        eeprom@50 {
+          compatible = "atmel,24c02";
+          reg = <0x50>;
+        };
+      };
+
+      i2c@1 {
+        reg = <1>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        eeprom@50 {
+          compatible = "atmel,24c02";
+          reg = <0x50>;
+        };
+      };
+    };