Describe the SGMII/SerDes PHY present on the Qualcomm sa8255p platforms.
This is essentially the same hardware as sa8775p rev3 but the PHY is
managed by firmware over SCMI.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
 .../bindings/phy/qcom,sa8255p-dwmac-sgmii-phy.yaml | 50 ++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/Documentation/devicetree/bindings/phy/qcom,sa8255p-dwmac-sgmii-phy.yaml b/Documentation/devicetree/bindings/phy/qcom,sa8255p-dwmac-sgmii-phy.yaml
new file mode 100644
index 0000000000000000000000000000000000000000..9e846e381555514bb32177f884abf0cf2c942948
--- /dev/null
+++ b/Documentation/devicetree/bindings/phy/qcom,sa8255p-dwmac-sgmii-phy.yaml
@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/phy/qcom,sa8255p-dwmac-sgmii-phy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm SerDes/SGMII ethernet PHY controller (firmware managed)
+
+maintainers:
+  - Bartosz Golaszewski <brgl@kernel.org>
+
+description:
+  The SerDes PHY sits between the MAC and the external PHY and provides
+  separate Rx Tx lines.
+
+properties:
+  compatible:
+    const: qcom,sa8255p-dwmac-sgmii-phy
+
+  reg:
+    items:
+      - description: serdes
+
+  power-domains:
+    maxItems: 1
+
+  power-domain-names:
+    maxItems: 1
+
+  "#phy-cells":
+    const: 0
+
+required:
+  - compatible
+  - reg
+  - "#phy-cells"
+  - power-domains
+  - power-domain-names
+
+additionalProperties: false
+
+examples:
+  - |
+    phy@8901000 {
+        compatible = "qcom,sa8255p-dwmac-sgmii-phy";
+        reg = <0x08901000 0xe10>;
+        #phy-cells = <0>;
+        power-domains = <&scmi7_dvfs 0>;
+        power-domain-names = "serdes";
+    };

-- 
2.47.3