eth: Add GMII PHY interface module

Signed-off-by: Alex Forencich <alex@alexforencich.com>

rtl/eth/taxi_gmii_phy_if.f

@@ -0,0 +1,5 @@
+taxi_gmii_phy_if.sv
+../io/taxi_ssio_sdr_in.sv
+../io/taxi_ssio_sdr_out.sv
+../io/taxi_oddr.sv
+../sync/taxi_sync_reset.sv

rtl/eth/taxi_gmii_phy_if.sv

@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: CERN-OHL-S-2.0
+/*
+
+Copyright (c) 2015-2025 FPGA Ninja, LLC
+
+Authors:
+- Alex Forencich
+
+*/
+
+`resetall
+`timescale 1ns / 1ps
+`default_nettype none
+
+/*
+ * GMII PHY interface
+ */
+module taxi_gmii_phy_if #
+(
+    // simulation (set to avoid vendor primitives)
+    parameter logic SIM = 1'b0,
+    // vendor ("GENERIC", "XILINX", "ALTERA")
+    parameter VENDOR = "XILINX",
+    // device family
+    parameter FAMILY = "virtex7"
+)
+(
+    input  wire logic        gtx_clk,
+    input  wire logic        gtx_rst,
+
+    /*
+     * GMII interface to MAC
+     */
+    output wire logic        mac_gmii_rx_clk,
+    output wire logic        mac_gmii_rx_rst,
+    output wire logic [7:0]  mac_gmii_rxd,
+    output wire logic        mac_gmii_rx_dv,
+    output wire logic        mac_gmii_rx_er,
+    output wire logic        mac_gmii_tx_clk,
+    output wire logic        mac_gmii_tx_rst,
+    input  wire logic [7:0]  mac_gmii_txd,
+    input  wire logic        mac_gmii_tx_en,
+    input  wire logic        mac_gmii_tx_er,
+
+    /*
+     * GMII interface to PHY
+     */
+    input  wire logic        phy_gmii_rx_clk,
+    input  wire logic [7:0]  phy_gmii_rxd,
+    input  wire logic        phy_gmii_rx_dv,
+    input  wire logic        phy_gmii_rx_er,
+    input  wire logic        phy_mii_tx_clk,
+    output wire logic        phy_gmii_tx_clk,
+    output wire logic [7:0]  phy_gmii_txd,
+    output wire logic        phy_gmii_tx_en,
+    output wire logic        phy_gmii_tx_er,
+
+    /*
+     * Control
+     */
+    input  wire logic        mii_select
+);
+
+taxi_ssio_sdr_in #(
+    .SIM(SIM),
+    .VENDOR(VENDOR),
+    .FAMILY(FAMILY),
+    .WIDTH(10)
+)
+rx_ssio_sdr_inst (
+    .input_clk(phy_gmii_rx_clk),
+    .input_d({phy_gmii_rxd, phy_gmii_rx_dv, phy_gmii_rx_er}),
+    .output_clk(mac_gmii_rx_clk),
+    .output_q({mac_gmii_rxd, mac_gmii_rx_dv, mac_gmii_rx_er})
+);
+
+taxi_ssio_sdr_out #(
+    .SIM(SIM),
+    .VENDOR(VENDOR),
+    .FAMILY(FAMILY),
+    .WIDTH(10)
+)
+tx_ssio_sdr_inst (
+    .clk(mac_gmii_tx_clk),
+    .input_d({mac_gmii_txd, mac_gmii_tx_en, mac_gmii_tx_er}),
+    .output_clk(phy_gmii_tx_clk),
+    .output_q({phy_gmii_txd, phy_gmii_tx_en, phy_gmii_tx_er})
+);
+
+if (!SIM && VENDOR == "XILINX") begin
+    // Xilinx/AMD device support
+
+    BUFGMUX
+    gmii_bufgmux_inst (
+        .I0(gtx_clk),
+        .I1(phy_mii_tx_clk),
+        .S(mii_select),
+        .O(mac_gmii_tx_clk)
+    );
+
+end else begin
+    // generic/simulation implementation (no vendor primitives)
+
+    assign mac_gmii_tx_clk = mii_select ? phy_mii_tx_clk : gtx_clk;
+
+end
+
+// reset sync
+taxi_sync_reset #(
+    .N(4)
+)
+tx_reset_sync_inst (
+    .clk(mac_gmii_tx_clk),
+    .rst(gtx_rst),
+    .out(mac_gmii_tx_rst)
+);
+
+taxi_sync_reset #(
+    .N(4)
+)
+rx_reset_sync_inst (
+    .clk(mac_gmii_rx_clk),
+    .rst(gtx_rst),
+    .out(mac_gmii_rx_rst)
+);
+
+endmodule
+
+`resetall