dt-bindings: net: add DAPU Telecom DAP8211R(I) PHY binding

Add device tree binding documentation for the DAPU Telecom DAP8211R(I)
Gigabit Ethernet PHY.

The PHY supports TX and RX clock delays in 150 ps steps from 0 to 2250 ps,
with a default of 1950 ps if not specified.

Signed-off-by: Artem Shimko <a.shimko.dev@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Link: https://patch.msgid.link/20260805085540.452260-3-a.shimko.dev@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/devicetree/bindings/net/dptel,dap8211r.yaml

@@ -0,0 +1,62 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/dptel,dap8211r.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: DAPU Telecom DAP8211R(I) Gigabit Ethernet PHY
+
+maintainers:
+  - Artem Shimko <a.shimko.dev@gmail.com>
+
+description: |
+  The DAP8211R(I) is a Gigabit Ethernet PHY with RGMII interface,
+  supporting IEEE 802.3az Energy Efficient Ethernet, IEEE 1588 SyncE,
+  and an internal packet generator for diagnostics.
+
+  Specifications:
+    - 10BASE-Te, 100BASE-TX, 1000BASE-T
+    - RGMII with configurable TX/RX clock delays (150 ps steps, 0-2250 ps)
+    - IEEE 802.3az-2010 Energy Efficient Ethernet
+    - IEEE 1588 SyncE support
+    - Internal packet generator and checker for link diagnostics
+
+allOf:
+  - $ref: ethernet-phy.yaml#
+
+properties:
+  compatible:
+    const: ethernet-phy-id0008.011b
+
+  reg:
+    maxItems: 1
+
+  rx-internal-delay-ps:
+    description:
+      RGMII RX clock delay in picoseconds (0 to maximum).
+    multipleOf: 150
+    maximum: 2250
+    default: 1950
+
+  tx-internal-delay-ps:
+    description:
+      RGMII TX clock delay in picoseconds (0 to maximum).
+    multipleOf: 150
+    maximum: 2250
+    default: 1950
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    mdio {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        ethernet-phy@1 {
+            compatible = "ethernet-phy-id0008.011b";
+            reg = <1>;
+            rx-internal-delay-ps = <1950>;
+            tx-internal-delay-ps = <1950>;
+        };
+    };