platforms: add arty_symbiflow

Signed-off-by: Mariusz Glebocki <mglebocki@antmicro.com>

litex/boards/platforms/arty_symbiflow.py

@@ -0,0 +1,35 @@
+# This file is Copyright (c) 2015-2019 Florent Kermarrec <florent@enjoy-digital.fr>
+# This file is Copyright (c) 2020 Antmicro <www.antmicro.com>
+# License: BSD
+
+from litex.build.generic_platform import *
+from litex.build.xilinx import XilinxPlatform
+from litex.build.openocd import OpenOCD
+from litex.boards.platforms.arty import _io, _connectors
+
+# Platform -----------------------------------------------------------------------------------------
+
+class Platform(XilinxPlatform):
+    default_clk_name   = "clk100"
+    default_clk_period = 1e9/100e6
+
+    def __init__(self, variant="a7-35"):
+        device = {
+            "a7-35":  {"part": "xc7a35tcsg324-1", "symbiflow-device": "xc7a50t_test"},
+        }[variant]
+        XilinxPlatform.__init__(self, device["part"], _io, _connectors, toolchain="symbiflow")
+        self.toolchain.symbiflow_device = device["symbiflow-device"]
+
+    def create_programmer(self):
+        bscan_spi = "bscan_spi_xc7a100t.bit" if "xc7a100t" in self.device else "bscan_spi_xc7a35t.bit"
+        return OpenOCD("openocd_xc7_ft2232.cfg", bscan_spi)
+
+    def do_finalize(self, fragment):
+        # Prevent GenericPlatform from creating period constraint on input clock
+        pass
+
+    def add_period_constraint(self, clk, period, phase=0):
+        if clk is None: return
+        if hasattr(clk, "p"):
+            clk = clk.p
+        self.toolchain.add_period_constraint(self, clk, period, phase)