The AC300 companion IC exposes the Fast Ethernet PHY control registers
through a separate non-PHY Clause 22 address. The manual defines the
control address as the link-PHY address plus 16, giving address ranges
of 16-23 and 0-7 respectively.

Describe the control endpoint, its required VCC1 supply, its 24, 25 or
27 MHz input clock, interface mode and calibration cell.

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
 .../bindings/net/x-powers,ac300-ephy-ctl.yaml      | 77 ++++++++++++++++++++++
 1 file changed, 77 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/x-powers,ac300-ephy-ctl.yaml b/Documentation/devicetree/bindings/net/x-powers,ac300-ephy-ctl.yaml
new file mode 100644
index 000000000000..a6634fcfafd4
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/x-powers,ac300-ephy-ctl.yaml
@@ -0,0 +1,77 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/x-powers,ac300-ephy-ctl.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: X-Powers AC300 Ethernet PHY control interface
+
+maintainers:
+  - James Hilliard <james.hilliard1@gmail.com>
+
+description:
+  The AC300 Fast Ethernet PHY has a separate control interface accessed as a
+  non-PHY Clause 22 device. Its address is 16 plus the address of the link PHY.
+
+properties:
+  compatible:
+    const: x-powers,ac300-ephy-ctl
+
+  reg:
+    minimum: 16
+    maximum: 23
+
+  clocks:
+    maxItems: 1
+    description:
+      AC300 input clock. Its configured rate must be 24, 25, or 27 MHz and
+      determines the corresponding EPHY_CLK_SEL value.
+
+  vcc1-supply:
+    description:
+      3.3 V supply for the AC300 I/O, bandgap, Ethernet PHY analog front end,
+      and internal digital LDO
+
+  nvmem-cells:
+    maxItems: 1
+    description:
+      SoC SID cell containing the Ethernet PHY calibration value written to
+      the AC300 BGS_EFFUSE field after adding 3 modulo 16, as prescribed by
+      the vendor initialization sequence.
+
+  nvmem-cell-names:
+    const: calibration
+
+  phy-mode:
+    enum:
+      - mii
+      - rmii
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - vcc1-supply
+  - nvmem-cells
+  - nvmem-cell-names
+  - phy-mode
+
+additionalProperties: false
+
+examples:
+  - |
+    mdio {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        ethernet-phy-control@10 {
+            compatible = "x-powers,ac300-ephy-ctl";
+            reg = <0x10>;
+            clocks = <&pwm 5>;
+            vcc1-supply = <&reg_3v3>;
+            nvmem-cells = <&ephy_calibration>;
+            nvmem-cell-names = "calibration";
+            phy-mode = "rmii";
+        };
+    };
+...

-- 
2.53.0