[PATCH net-next v6 2/6] dt-bindings: net: Add Realtek MDIO controller

[Chris Packham <chris.packham@alliedtelesis.co.nz>]

Add dtschema for the MDIO controller found in the RTL9300 SoCs. The
controller is slightly unusual in that direct MDIO communication is not
possible. We model the MDIO controller with the MDIO buses as child
nodes and the PHYs as children of the buses. The mapping of switch port
number to MDIO bus/addr requires the ethernet-ports sibling to provide
the mapping via the phy-handle property.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---

Notes:
    Changes in v6:
    - Remove realtek,port property. The driver will parse the ethernet-ports
      sibling node to figure out the mapping (do I need to mention that
      somewhere in this binding?).
    - Correct number of mdio buses. 4 possible buses numbered 0-3.
    Changes in v5:
    - Add back reg property to mdio-controller node
    - Make unit address in the node name required
    - Andrew suggested perhaps doing away with the realtek,port property and
      providing the overall mapping via an array of phandles. I've explored
      this a little, it is doable but I'm not sure it actually makes things
      any clearer when the portmap has gaps so I haven't made this change.
    Changes in v4:
    - Model the MDIO controller with the buses as child nodes. We still need
      to deal with the switch port number so this is represented with the
      "realtek,port" property which needs to be added to the MDIO bus
      children (i.e. the PHYs)
    - Because the above is quite a departure from earlier I've dropped the
      r-by
    Changes in v3:
    - Add r-by from Connor
    Changes in v2:
    - None

 .../bindings/net/realtek,rtl9301-mdio.yaml    | 86 +++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/realtek,rtl9301-mdio.yaml

diff --git a/Documentation/devicetree/bindings/net/realtek,rtl9301-mdio.yaml b/Documentation/devicetree/bindings/net/realtek,rtl9301-mdio.yaml
new file mode 100644
index 000000000000..02e4e33e9969
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/realtek,rtl9301-mdio.yaml
@@ -0,0 +1,86 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/realtek,rtl9301-mdio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Realtek RTL9300 MDIO Controller
+
+maintainers:
+  - Chris Packham <chris.packham@alliedtelesis.co.nz>
+
+properties:
+  compatible:
+    oneOf:
+      - items:
+          - enum:
+              - realtek,rtl9302b-mdio
+              - realtek,rtl9302c-mdio
+              - realtek,rtl9303-mdio
+          - const: realtek,rtl9301-mdio
+      - const: realtek,rtl9301-mdio
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+  reg:
+    maxItems: 1
+
+patternProperties:
+  '^mdio-bus@[0-3]$':
+    $ref: mdio.yaml#
+
+    properties:
+      reg:
+        maxItems: 1
+
+    required:
+      - reg
+
+    patternProperties:
+      '^ethernet-phy@[a-f0-9]+$':
+        type: object
+        $ref: ethernet-phy.yaml#
+        unevaluatedProperties: false
+
+    unevaluatedProperties: false
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    mdio-controller@ca00 {
+      compatible = "realtek,rtl9301-mdio";
+      reg = <0xca00 0x200>;
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      mdio-bus@0 {
+        reg = <0>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        ethernet-phy@0 {
+          compatible = "ethernet-phy-ieee802.3-c45";
+          reg = <0>;
+        };
+      };
+
+      mdio-bus@1 {
+        reg = <1>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        ethernet-phy@0 {
+          compatible = "ethernet-phy-ieee802.3-c45";
+          reg = <0>;
+        };
+      };
+    };
-- 
2.48.1