gensoc: call do_exit after SoC is built

make.py

@@ -182,7 +182,8 @@ CPU type:  {}
 		for decorator in args.decorate:
 			soc = getattr(simplify, decorator)(soc)
 		build_kwargs = dict((k, autotype(v)) for k, v in args.build_option)
-		platform.build(soc, build_name=build_name, **build_kwargs)
+		vns = platform.build(soc, build_name=build_name, **build_kwargs)
+		soc.do_exit(vns)
 
 	if actions["load-bitstream"] or actions["flash-bitstream"] or actions["flash-bios"]:
 		prog = platform.create_programmer()

misoclib/gensoc/__init__.py

@@ -138,6 +138,9 @@ class GenSoC(Module):
 			t += clk_period_ns/2
 		return ceil(t/clk_period_ns)
 
+	def do_exit(self, vns):
+		pass
+
 class IntegratedBIOS:
 	def __init__(self, bios_size=0x8000):
 		self.submodules.rom = wishbone.SRAM(bios_size, read_only=True)