forest_kitten_33: add minimal target and use es1.

Tested with:
./forest_kitten_33.py --uart-name=jtag_uart --build --load
litex/tools/litex_jtag_uart.py
lxterm /dev/pts/X

litex_boards/platforms/forest_kitten_33.py

@@ -46,7 +46,7 @@ class Platform(XilinxPlatform):
     default_clk_period = 1e9/200e6
 
     def __init__(self):
-        XilinxPlatform.__init__(self, "xcvu33p-fsvh2104-2L-e", _io, toolchain="vivado")
+        XilinxPlatform.__init__(self, "xcvu33p-fsvh2104-2L-e-es1", _io, toolchain="vivado")
 
     def create_programmer(self):
         return VivadoProgrammer()

litex_boards/targets/forest_kitten_33.py

@@ -0,0 +1,67 @@
+#!/usr/bin/env python3
+
+# This file is Copyright (c) 2020 Florent Kermarrec <florent@enjoy-digital.fr>
+# License: BSD
+
+import os
+import argparse
+
+from migen import *
+
+from litex_boards.platforms import forest_kitten_33
+
+from litex.soc.cores.clock import *
+from litex.soc.integration.soc_core import *
+from litex.soc.integration.builder import *
+from litex.soc.cores.led import LedChaser
+
+# CRG ----------------------------------------------------------------------------------------------
+
+class _CRG(Module):
+    def __init__(self, platform, sys_clk_freq):
+        self.clock_domains.cd_sys    = ClockDomain()
+
+        # # #
+
+        self.submodules.pll = pll = USMMCM(speedgrade=-2)
+        pll.register_clkin(platform.request("clk200"), 200e6)
+        pll.create_clkout(self.cd_sys, sys_clk_freq)
+
+# BaseSoC ------------------------------------------------------------------------------------------
+
+class BaseSoC(SoCCore):
+    def __init__(self, sys_clk_freq=int(125e6), **kwargs):
+        platform = forest_kitten_33.Platform()
+
+        # SoCCore ----------------------------------------------------------------------------------
+        SoCCore.__init__(self, platform, clk_freq=sys_clk_freq, **kwargs)
+
+        # CRG --------------------------------------------------------------------------------------
+        self.submodules.crg = _CRG(platform, sys_clk_freq)
+
+        # Leds -------------------------------------------------------------------------------------
+        self.submodules.leds = LedChaser(
+            pads         = Cat(*[platform.request("user_led", i) for i in range(7)]),
+            sys_clk_freq = sys_clk_freq)
+        self.add_csr("leds")
+
+# Build --------------------------------------------------------------------------------------------
+
+def main():
+    parser = argparse.ArgumentParser(description="LiteX SoC on Forest Kitten 33")
+    parser.add_argument("--build", action="store_true", help="Build bitstream")
+    parser.add_argument("--load",  action="store_true", help="Load bitstream")
+    builder_args(parser)
+    soc_core_args(parser)
+    args = parser.parse_args()
+
+    soc = BaseSoC(**soc_core_argdict(args))
+    builder = Builder(soc, **builder_argdict(args))
+    builder.build(run=args.build)
+
+    if args.load:
+        prog = soc.platform.create_programmer()
+        prog.load_bitstream(os.path.join(builder.gateware_dir, soc.build_name + ".bit"))
+
+if __name__ == "__main__":
+    main()