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

GPIO-based I2C Bus Mux

This binding describes an I2C bus multiplexer that uses GPIOs to

route the I2C signals.

                                  +-----+  +-----+

                                  | dev |  | dev |

    +------------+                +-----+  +-----+

    | SoC        |                   |        |

    |            |          /--------+--------+

    |   +------+ |  +------+    child bus A, on GPIO value set to 0

    |   | I2C  |-|--| Mux  |

    |   +------+ |  +--+---+    child bus B, on GPIO value set to 1

    |            |     |    \----------+--------+--------+

    |   +------+ |     |               |        |        |

    |   | GPIO |-|-----+            +-----+  +-----+  +-----+

    |   +------+ |                  | dev |  | dev |  | dev |

    +------------+                  +-----+  +-----+  +-----+

Required properties:

- compatible: i2c-mux-gpio

- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side

  port is connected to.

- mux-gpios: list of gpios used to control the muxer

* Standard I2C mux properties. See i2c-mux.yaml in this directory.

* I2C child bus nodes. See i2c-mux.yaml in this directory.

Optional properties:

- idle-state: value to set the muxer to when idle. When no value is

  given, it defaults to the last value used.

For each i2c child node, an I2C child bus will be created. They will

be numbered based on their order in the device tree.

Whenever an access is made to a device on a child bus, the value set

in the relevant node's reg property will be output using the list of

GPIOs, the first in the list holding the least-significant value.

If an idle state is defined, using the idle-state (optional) property,

whenever an access is not being made to a device on a child bus, the

GPIOs will be set according to the idle value.

If an idle state is not defined, the most recently used value will be

left programmed into hardware whenever no access is being made to a

device on a child bus.

Example:

	i2cmux {

		compatible = "i2c-mux-gpio";

		#address-cells = <1>;

		#size-cells = <0>;

		mux-gpios = <&gpio1 22 0 &gpio1 23 0>;

		i2c-parent = <&i2c1>;

		i2c@1 {

			reg = <1>;

			#address-cells = <1>;

			#size-cells = <0>;

			ssd1307: oled@3c {

				compatible = "solomon,ssd1307fb-i2c";

				reg = <0x3c>;

				pwms = <&pwm 4 3000>;

				reset-gpios = <&gpio2 7 1>;

			};

		};

		i2c@3 {

			reg = <3>;

			#address-cells = <1>;

			#size-cells = <0>;

			pca9555: pca9555@20 {

				compatible = "nxp,pca9555";

				gpio-controller;

				#gpio-cells = <2>;

				reg = <0x20>;

			};

		};

	};

# SPDX-License-Identifier: GPL-2.0-only

%YAML 1.2

---

$id: http://devicetree.org/schemas/i2c/i2c-mux-gpio.yaml#

$schema: http://devicetree.org/meta-schemas/core.yaml#

title: GPIO-based I2C Bus Mux

maintainers:

  - Wolfram Sang <wsa@kernel.org>

description: |

  This binding describes an I2C bus multiplexer that uses GPIOs to route the I2C signals.

                                  +-----+  +-----+

                                  | dev |  | dev |

    +------------+                +-----+  +-----+

    | SoC        |                   |        |

    |            |          /--------+--------+

    |   +------+ |  +------+    child bus A, on GPIO value set to 0

    |   | I2C  |-|--| Mux  |

    |   +------+ |  +--+---+    child bus B, on GPIO value set to 1

    |            |     |    \----------+--------+--------+

    |   +------+ |     |               |        |        |

    |   | GPIO |-|-----+            +-----+  +-----+  +-----+

    |   +------+ |                  | dev |  | dev |  | dev |

    +------------+                  +-----+  +-----+  +-----+

  For each I2C child node, an I2C child bus will be created. They will be numbered based on their

  order in the device tree.

  Whenever an access is made to a device on a child bus, the value set in the relevant node's reg

  property will be output using the list of GPIOs, the first in the list holding the least-

  significant value.

  If an idle state is defined, using the idle-state (optional) property, whenever an access is not

  being made to a device on a child bus, the GPIOs will be set according to the idle value.

  If an idle state is not defined, the most recently used value will be left programmed into

  hardware whenever no access is being made to a device on a child bus.

properties:

  compatible:

    const: i2c-mux-gpio

  i2c-parent:

    description: phandle of the I2C bus that this multiplexer's master-side port is connected to

    $ref: "/schemas/types.yaml#/definitions/phandle"

  mux-gpios:

    description: list of GPIOs used to control the muxer

    minItems: 1

    maxItems: 4  # Should be enough

  idle-state:

    description: Value to set the muxer to when idle. When no value is given, it defaults to the

      last value used.

    $ref: "/schemas/types.yaml#/definitions/uint32"

allOf:

  - $ref: i2c-mux.yaml

unevaluatedProperties: false

required:

  - compatible

  - i2c-parent

  - mux-gpios

examples:

  - |

    i2cmux {

      compatible = "i2c-mux-gpio";

      #address-cells = <1>;

      #size-cells = <0>;

      mux-gpios = <&gpio1 22 0>, <&gpio1 23 0>;

      i2c-parent = <&i2c1>;

      i2c@1 {

        reg = <1>;

        #address-cells = <1>;

        #size-cells = <0>;

        ssd1307: oled@3c {

          compatible = "solomon,ssd1307fb-i2c";

          reg = <0x3c>;

          pwms = <&pwm 4 3000>;

          reset-gpios = <&gpio2 7 1>;

        };

      };

      i2c@3 {

        reg = <3>;

        #address-cells = <1>;

        #size-cells = <0>;

        pca9555: pca9555@20 {

          compatible = "nxp,pca9555";

          gpio-controller;

          #gpio-cells = <2>;

          reg = <0x20>;

        };

      };

    };