liteeth_gen: Add specific A7_1000BASEX support and example configuration.

Adapted from known working targets but untested on hardware.

examples/udp_a7_gtp_sgmii.yml

@@ -0,0 +1,26 @@
+#
+# This file is part of LiteEth.
+#
+# Copyright (c) 2020-2024 Florent Kermarrec <florent@enjoy-digital.fr>
+# SPDX-License-Identifier: BSD-2-Clause
+
+# PHY ----------------------------------------------------------------------
+phy       : A7_1000BASEX
+vendor    : xilinx
+toolchain : vivado
+
+# Core ---------------------------------------------------------------------
+refclk_freq : 200e6
+clk_freq    : 25e6
+core        : udp
+data_width  : 32
+dhcp        : True
+
+# UDP Ports --------------------------------------------------------------------
+udp_ports:   {
+  "udp0": {
+    "data_width"    : 32,
+    "tx_fifo_depth" : 1024,
+    "rx_fifo_depth" : 1024,
+  },
+}

liteeth/gen.py

@@ -284,6 +284,27 @@ class PHYCore(SoCMini):
             liteeth_phys.USP_GTY_1000BASEX,
         ]:
             ethphy_pads = platform.request("sgmii")
+            # Artix7.
+            if phy in [liteeth_phys.A7_1000BASEX]:
+                assert core_config.get("refclk_freq", 0) == 200e6
+                from liteeth.phy.a7_gtp import QPLLSettings, QPLL
+                qpll_settings = QPLLSettings(
+                    refclksel  = 0b001,
+                    fbdiv      = 4,
+                    fbdiv_45   = 5,
+                    refclk_div = 1
+                )
+                qpll = QPLL(ethphy_pads.refclk, qpll_settings)
+                ethphy = phy(
+                    qpll_channel = qpll.channels[0],
+                    data_pads    = ethphy_pads,
+                    sys_clk_freq = self.clk_freq,
+                    with_csr     = False,
+                    rx_polarity  = 0, # Add support to liteeth_gen if useful.
+                    tx_polarity  = 0, # Add support to liteeth_gen if useful.
+                )
+            # Other 7-Series/Ultrascale(+).
+            else:
                 ethphy = phy(
                     refclk_or_clk_pads = ethphy_pads.refclk,
                     data_pads          = ethphy_pads,