dt-bindings: net: adin: document phy clock output properties

The ADIN1300 supports generating certain clocks on its GP_CLK pin, as
well as providing the reference clock on CLK25_REF.

Add DT properties to configure both pins.

Technically the phy also supports a recovered 125MHz clock for
synchronous ethernet. However SyncE should be configured dynamically at
runtime, so it is explicitly omitted in this binding.

Signed-off-by: Josua Mayer <josua@solid-run.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/devicetree/bindings/net/adi,adin.yaml

@@ -36,6 +36,21 @@ properties:
     enum: [ 4, 8, 12, 16, 20, 24 ]
     default: 8
 
+  adi,phy-output-clock:
+    description: Select clock output on GP_CLK pin. Two clocks are available:
+      A 25MHz reference and a free-running 125MHz.
+      The phy can alternatively automatically switch between the reference and
+      the 125MHz clocks based on its internal state.
+    $ref: /schemas/types.yaml#/definitions/string
+    enum:
+      - 25mhz-reference
+      - 125mhz-free-running
+      - adaptive-free-running
+
+  adi,phy-output-reference-clock:
+    description: Enable 25MHz reference clock output on CLK25_REF pin.
+    type: boolean
+
 unevaluatedProperties: false
 
 examples: