dt-bindings: serial: Add bindings for nvidia,tegra264-utc

The Tegra UTC (UART Trace Controller) allows multiple clients within
the Tegra SoC to share a physical UART interface. It supports up to 16
clients. Each client operates as an independent UART endpoint with a
dedicated interrupt and 128-character TX/RX FIFOs.

Add device tree binding documentation for the Tegra UTC client.

Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20250213125612.4705-2-kkartik@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/serial/nvidia,tegra264-utc.yaml

@@ -0,0 +1,73 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/serial/nvidia,tegra264-utc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NVIDIA Tegra UTC (UART Trace Controller) client
+
+maintainers:
+  - Kartik Rajput <kkartik@nvidia.com>
+  - Thierry Reding <thierry.reding@gmail.com>
+  - Jonathan Hunter <jonathanh@nvidia.com>
+
+description:
+  Represents a client interface of the Tegra UTC (UART Trace Controller). The
+  Tegra UTC allows multiple clients within the Tegra SoC to share a physical
+  UART interface. It supports up to 16 clients. Each client operates as an
+  independent UART endpoint with a dedicated interrupt and 128-character TX/RX
+  FIFOs.
+
+  The Tegra UTC clients use 8-N-1 configuration and operates on a baudrate
+  configured by the bootloader at the controller level.
+
+allOf:
+  - $ref: serial.yaml#
+
+properties:
+  compatible:
+    const: nvidia,tegra264-utc
+
+  reg:
+    items:
+      - description: TX region.
+      - description: RX region.
+
+  reg-names:
+    items:
+      - const: tx
+      - const: rx
+
+  interrupts:
+    maxItems: 1
+
+  tx-threshold:
+    minimum: 1
+    maximum: 128
+
+  rx-threshold:
+    minimum: 1
+    maximum: 128
+
+required:
+  - compatible
+  - reg
+  - reg-names
+  - interrupts
+  - tx-threshold
+  - rx-threshold
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    tegra_utc: serial@c4e0000 {
+        compatible = "nvidia,tegra264-utc";
+        reg = <0xc4e0000 0x8000>, <0xc4e8000 0x8000>;
+        reg-names = "tx", "rx";
+        interrupts = <GIC_SPI 514 IRQ_TYPE_LEVEL_HIGH>;
+        tx-threshold = <4>;
+        rx-threshold = <4>;
+    };