[PATCH v2 1/2] dt-bindings: i2c: Add i2c-shared-gpio

[Markus Stockhausen <markus.stockhausen@gmx.de>]

Document the driver for bitbanged gpio I2C busses
with shared SCL lines.

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
---
 .../bindings/i2c/i2c-gpio-shared.yaml         | 105 ++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-gpio-shared.yaml

diff --git a/Documentation/devicetree/bindings/i2c/i2c-gpio-shared.yaml b/Documentation/devicetree/bindings/i2c/i2c-gpio-shared.yaml
new file mode 100644
index 000000000000..4a21638bd842
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-gpio-shared.yaml
@@ -0,0 +1,105 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/i2c/i2c-gpio-shared.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Multiple GPIO bitbanged I2C buses with shared SCL
+
+maintainers:
+  - Markus Stockhausen <markus.stockhausen@gmx.de>
+
+description:
+  Bitbanging I2C bus driver that supports multiple independent I2C buses
+  sharing a single SCL line. Each child node represents one I2C bus with
+  its own SDA line. The index of each entry in the parent's sda-gpios
+  property must match the reg value of the corresponding child bus node.
+
+properties:
+  compatible:
+    const: i2c-gpio-shared
+
+  scl-gpios:
+    maxItems: 1
+    description:
+      GPIO used for the shared SCL signal. Must be configured as open-drain.
+
+  sda-gpios:
+    minItems: 2
+    maxItems: 32
+    description:
+      GPIOs used for the SDA signals of the individual I2C buses. The index
+      of the GPIO in this list corresponds to the 'reg' property of the
+      child bus nodes (e.g., the first GPIO is for the child with reg = <0>).
+      Must be configured as open-drain.
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+required:
+  - compatible
+  - scl-gpios
+  - sda-gpios
+  - "#address-cells"
+  - "#size-cells"
+
+patternProperties:
+  "^i2c@[0-9a-f]+$":
+    type: object
+    $ref: /schemas/i2c/i2c-controller.yaml#
+    unevaluatedProperties: false
+
+    properties:
+      reg:
+        items:
+          - minimum: 0
+            maximum: 31
+        description:
+          Index into the sda-gpios array used by this specific bus.
+
+      clock-frequency:
+        minimum: 1
+        maximum: 400000
+        default: 100000
+        description:
+          Desired I2C bus clock frequency in Hz.
+
+    required:
+      - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    i2c {
+        compatible = "i2c-gpio-shared";
+        scl-gpios = <&gpio1 31 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
+        sda-gpios = <&gpio1 6 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>,
+                    <&gpio1 7 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        i2c@0 {
+            reg = <0>;
+            clock-frequency = <100000>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            eeprom@50 {
+                compatible = "atmel,24c02";
+                reg = <0x50>;
+            };
+        };
+
+        i2c@1 {
+            reg = <1>;
+            clock-frequency = <400000>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+        };
+    };
-- 
2.54.0