Introduce `mdio-parent-bus` property in the ksz DSA bindings to
reference the parent MDIO bus when the internal MDIO bus is attached to
it, bypassing the main management interface.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
 .../devicetree/bindings/net/dsa/microchip,ksz.yaml       | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml b/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml
index a4e463819d4d7..121a4bbd147be 100644
--- a/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml
+++ b/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml
@@ -84,6 +84,15 @@ properties:
   mdio:
     $ref: /schemas/net/mdio.yaml#
     unevaluatedProperties: false
+    properties:
+      mdio-parent-bus:
+        $ref: /schemas/types.yaml#/definitions/phandle
+        description:
+          Phandle pointing to the MDIO bus controller connected to the
+          secondary MDIO interface. This property should be used when
+          the internal MDIO bus is accessed via a secondary MDIO
+          interface rather than the primary management interface.
+
     patternProperties:
       "^ethernet-phy@[0-9a-f]$":
         type: object
-- 
2.39.5