dt-bindings: w1: UART 1-Wire bus

Add device tree binding for UART 1-Wire bus.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Christoph Winklhofer <cj.winklhofer@gmail.com>
Link: https://lore.kernel.org/r/20240209-w1-uart-v6-2-3e753c149196@gmail.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

diff --git a/Documentation/devicetree/bindings/w1/w1-uart.yaml b/Documentation/devicetree/bindings/w1/w1-uart.yaml
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+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/w1/w1-uart.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: UART 1-Wire Bus
+
+maintainers:
+  - Christoph Winklhofer <cj.winklhofer@gmail.com>
+
+description: |
+  UART 1-wire bus. Utilizes the UART interface via the Serial Device Bus
+  to create the 1-Wire timing patterns.
+
+  The UART peripheral must support full-duplex and operate in open-drain
+  mode. The timing patterns are generated by a specific combination of
+  baud-rate and transmitted byte, which corresponds to a 1-Wire read bit,
+  write bit or reset pulse.
+
+  The default baud-rate for reset and presence detection is 9600 and for
+  a 1-Wire read or write operation 115200. In case the actual baud-rate
+  is different from the requested one, the transmitted byte is adapted
+  to generate the 1-Wire timing patterns.
+
+  https://www.analog.com/en/technical-articles/using-a-uart-to-implement-a-1wire-bus-master.html
+
+properties:
+  compatible:
+    const: w1-uart
+
+  reset-bps:
+    default: 9600
+    description:
+      The baud rate for the 1-Wire reset and presence detect.
+
+  write-0-bps:
+    default: 115200
+    description:
+      The baud rate for the 1-Wire write-0 cycle.
+
+  write-1-bps:
+    default: 115200
+    description:
+      The baud rate for the 1-Wire write-1 and read cycle.
+
+required:
+  - compatible
+
+additionalProperties:
+  type: object
+
+examples:
+  - |
+    serial {
+        onewire {
+            compatible = "w1-uart";
+        };
+    };