dt-bindings: net: Add T-HEAD dwmac support

Add documentation to describe the DesginWare-based GMAC controllers in
the T-HEAD TH1520 SoC.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Signed-off-by: Drew Fustini <dfustini@tenstorrent.com>
Link: https://patch.msgid.link/20241103-th1520-gmac-v7-1-ef094a30169c@tenstorrent.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/devicetree/bindings/net/snps,dwmac.yaml

@@ -101,6 +101,7 @@ properties:
         - snps,dwxgmac-2.10
         - starfive,jh7100-dwmac
         - starfive,jh7110-dwmac
+        - thead,th1520-gmac
 
   reg:
     minItems: 1

Documentation/devicetree/bindings/net/thead,th1520-gmac.yaml

@@ -0,0 +1,110 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/thead,th1520-gmac.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: T-HEAD TH1520 GMAC Ethernet controller
+
+maintainers:
+  - Drew Fustini <dfustini@tenstorrent.com>
+
+description: |
+  The TH1520 GMAC is described in the TH1520 Peripheral Interface User Manual
+  https://git.beagleboard.org/beaglev-ahead/beaglev-ahead/-/tree/main/docs
+
+  Features include
+    - Compliant with IEEE802.3 Specification
+    - IEEE 1588-2008 standard for precision networked clock synchronization
+    - Supports 10/100/1000Mbps data transfer rate
+    - Supports RGMII/MII interface
+    - Preamble and start of frame data (SFD) insertion in Transmit path
+    - Preamble and SFD deletion in the Receive path
+    - Automatic CRC and pad generation options for receive frames
+    - MDIO master interface for PHY device configuration and management
+
+  The GMAC Registers consists of two parts
+    - APB registers are used to configure clock frequency/clock enable/clock
+      direction/PHY interface type.
+    - AHB registers are use to configure GMAC core (DesignWare Core part).
+      GMAC core register consists of DMA registers and GMAC registers.
+
+select:
+  properties:
+    compatible:
+      contains:
+        enum:
+          - thead,th1520-gmac
+  required:
+    - compatible
+
+allOf:
+  - $ref: snps,dwmac.yaml#
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - thead,th1520-gmac
+      - const: snps,dwmac-3.70a
+
+  reg:
+    items:
+      - description: DesignWare GMAC IP core registers
+      - description: GMAC APB registers
+
+  reg-names:
+    items:
+      - const: dwmac
+      - const: apb
+
+  clocks:
+    items:
+      - description: GMAC main clock
+      - description: Peripheral registers interface clock
+
+  clock-names:
+    items:
+      - const: stmmaceth
+      - const: pclk
+
+  interrupts:
+    items:
+      - description: Combined signal for various interrupt events
+
+  interrupt-names:
+    items:
+      - const: macirq
+
+required:
+  - clocks
+  - clock-names
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    gmac0: ethernet@e7070000 {
+        compatible = "thead,th1520-gmac", "snps,dwmac-3.70a";
+        reg = <0xe7070000 0x2000>, <0xec003000 0x1000>;
+        reg-names = "dwmac", "apb";
+        clocks = <&clk 1>, <&clk 2>;
+        clock-names = "stmmaceth", "pclk";
+        interrupts = <66>;
+        interrupt-names = "macirq";
+        phy-mode = "rgmii-id";
+        snps,fixed-burst;
+        snps,axi-config = <&stmmac_axi_setup>;
+        snps,pbl = <32>;
+        phy-handle = <&phy0>;
+
+        mdio {
+            #address-cells = <1>;
+            #size-cells = <0>;
+            compatible = "snps,dwmac-mdio";
+
+            phy0: ethernet-phy@0 {
+                reg = <0>;
+            };
+        };
+    };

MAINTAINERS

@@ -19845,6 +19845,7 @@ L:	linux-riscv@lists.infradead.org
 S:	Maintained
 T:	git https://github.com/pdp7/linux.git
 F:	Documentation/devicetree/bindings/clock/thead,th1520-clk-ap.yaml
+F:	Documentation/devicetree/bindings/net/thead,th1520-gmac.yaml
 F:	arch/riscv/boot/dts/thead/
 F:	drivers/clk/thead/clk-th1520-ap.c
 F:	include/dt-bindings/clock/thead,th1520-clk-ap.h