This MDIO hardware is based on a Microsemi design supported in Linux by
mdio-mscc-miim.c. However, The register interface is completely different
with pic64hpsc, hence the need for separate documentation.

The hardware supports C22 and C45.

The documentation recommends an input clock of 156.25MHz and a prescaler
of 39, which yields an MDIO clock of 1.95MHz.

The hardware supports an interrupt pin to signal transaction completion
which is not strictly needed as the software can also poll a "TRIGGER"
bit for this.

Signed-off-by: Charles Perry <charles.perry@microchip.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
---

Notes:
    Changes in v5:
      - Collect Conor's Acked-by
      - Remove the "|" in "description: |" (Rob)
      - Don't mention how many instances of the MDIO controller there are (Rob)
      - Hex addresses are now in lowercase (Rob)
      - Drop the phy DT label in the example (Rob)
    
    Changes in v4: none
    Changes in v3: none
    
    Changes in v2:
      - Make "clocks" and "interrupts" required (Andrew)
      - Add a default value to "clock-frequency" (Andrew)
    
    Changes in v5: none
    Changes in v4: none
    Changes in v3: none
    
    Changes in v2:
      - Make "clocks" and "interrupts" required (Andrew)
      - Add a default value to "clock-frequency" (Andrew)

 .../net/microchip,pic64hpsc-mdio.yaml         | 68 +++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/microchip,pic64hpsc-mdio.yaml

diff --git a/Documentation/devicetree/bindings/net/microchip,pic64hpsc-mdio.yaml b/Documentation/devicetree/bindings/net/microchip,pic64hpsc-mdio.yaml
new file mode 100644
index 000000000000..20f29b71566b
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/microchip,pic64hpsc-mdio.yaml
@@ -0,0 +1,68 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/microchip,pic64hpsc-mdio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip PIC64-HPSC/HX MDIO controller
+
+maintainers:
+  - Charles Perry <charles.perry@microchip.com>
+
+description:
+  This is the MDIO bus controller present in Microchip PIC64-HPSC/HX SoCs. It
+  supports C22 and C45 register access and is named "MDIO Initiator" in the
+  documentation.
+
+allOf:
+  - $ref: mdio.yaml#
+
+properties:
+  compatible:
+    oneOf:
+      - const: microchip,pic64hpsc-mdio
+      - items:
+          - const: microchip,pic64hx-mdio
+          - const: microchip,pic64hpsc-mdio
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-frequency:
+    default: 2500000
+
+  interrupts:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - interrupts
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    bus {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        mdio@4000c21e000 {
+            compatible = "microchip,pic64hpsc-mdio";
+            reg = <0x400 0x0c21e000 0x0 0x1000>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+            clocks = <&svc_clk>;
+            interrupt-parent = <&saplic0>;
+            interrupts = <168 IRQ_TYPE_LEVEL_HIGH>;
+
+            ethernet-phy@0 {
+                reg = <0>;
+            };
+        };
+    };
-- 
2.47.3