dt-bindings: phy: qcom,m31: Document qcom,m31 USB phy

Document the M31 USB2 phy present in IPQ5332.
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Co-developed-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
Signed-off-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>
Link: https://lore.kernel.org/r/44a31cf0361df8db527684c7fb3b38e6ece950c1.1691999761.git.quic_varada@quicinc.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/qcom,ipq5332-usb-hsphy.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/phy/qcom,ipq5332-usb-hsphy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: M31 USB PHY
+
+maintainers:
+  - Sricharan Ramabadhran <quic_srichara@quicinc.com>
+  - Varadarajan Narayanan <quic_varada@quicinc.com>
+
+description:
+  USB M31 PHY (https://www.m31tech.com) found in Qualcomm
+  IPQ5018, IPQ5332 SoCs.
+
+properties:
+  compatible:
+    items:
+      - const: qcom,ipq5332-usb-hsphy
+
+  "#phy-cells":
+    const: 0
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    items:
+      - const: cfg_ahb
+
+  resets:
+    maxItems: 1
+
+  vdd-supply:
+    description:
+      Phandle to 5V regulator supply to PHY digital circuit.
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/qcom,ipq5332-gcc.h>
+    usb-phy@7b000 {
+        compatible = "qcom,ipq5332-usb-hsphy";
+        reg = <0x0007b000 0x12c>;
+
+        clocks = <&gcc GCC_USB0_PHY_CFG_AHB_CLK>;
+        clock-names = "cfg_ahb";
+
+        #phy-cells = <0>;
+
+        resets = <&gcc GCC_QUSB2_0_PHY_BCR>;
+
+        vdd-supply = <&regulator_fixed_5p0>;
+    };