diff --git a/migen/pytholite/io.py b/migen/pytholite/io.py
index 89effa637..04fb171ee 100644
--- a/migen/pytholite/io.py
+++ b/migen/pytholite/io.py
@@ -1,8 +1,10 @@
 import ast
+from itertools import zip_longest
 
 from migen.fhdl.structure import *
 from migen.uio.ioo import UnifiedIOObject
 from migen.actorlib.sim import *
+from migen.bus import wishbone
 from migen.bus.transactions import *
 from migen.pytholite.fsm import *
 from migen.pytholite.expr import ExprCompiler
@@ -32,14 +34,12 @@ class _TokenPullExprCompiler(ExprCompiler):
 		
 		return signal
 
-def gen_df_io(compiler, modelname, to_model, from_model):
-	if len(to_model) == 1 or len(to_model) == 2:
-		epname = ast.literal_eval(to_model[0])
-		ep = compiler.ioo.endpoints[epname]
-	else:
-		raise TypeError("Token() takes 1 or 2 arguments")
+def _gen_df_io(compiler, modelname, to_model, from_model):
+	epname = ast.literal_eval(to_model["endpoint"])
+	values = to_model["value"]
+	ep = compiler.ioo.endpoints[epname]
 	
-	if len(to_model) == 1:
+	if isinstance(values, ast.Name) and values.id == "None":
 		# token pull from sink
 		if not isinstance(ep, Sink):
 			raise TypeError("Attempted to pull from source")
@@ -59,11 +59,10 @@ def gen_df_io(compiler, modelname, to_model, from_model):
 			raise TypeError("Attempted to push to sink")
 		if from_model:
 			raise TypeError("Attempted to read from pushed token")
-		d = to_model[1]
-		if not isinstance(d, ast.Dict):
+		if not isinstance(values, ast.Dict):
 			raise NotImplementedError
 		state = []
-		for akey, value in zip(d.keys, d.values):
+		for akey, value in zip(values.keys, values.values):
 			key = ast.literal_eval(akey)
 			signal = getattr(ep.token, key)
 			state.append(signal.eq(compiler.ec.visit_expr(value)))
@@ -73,8 +72,79 @@ def gen_df_io(compiler, modelname, to_model, from_model):
 		]
 		return [state], [state]
 
-def gen_io(compiler, modelname, model, to_model, from_model):
+def _gen_wishbone_io(compiler, modelname, model, to_model, from_model, bus):
+	state = [
+		bus.cyc.eq(1),
+		bus.stb.eq(1),
+		bus.adr.eq(compiler.ec.visit_expr(to_model["address"])),
+	]
+	
+	if model == TWrite:
+		state.append(bus.we.eq(1))
+		if from_model:
+			raise TypeError("Attempted to read from write transaction")
+	else:
+		state.append(bus.we.eq(0))
+		# TODO
+	state.append(If(~bus.ack, AbstractNextState(state)))
+	return [state], [state]
+
+def _gen_bus_io(compiler, modelname, model, to_model, from_model):
+	busname = ast.literal_eval(to_model["busname"])
+	if busname is None:
+		if len(compiler.ioo.buses) != 1:
+			raise TypeError("Bus name not specified")
+		bus = list(compiler.ioo.buses.values())[0]
+	else:
+		bus = compiler.ioo.buses[busname]
+	if isinstance(bus, wishbone.Interface):
+		return _gen_wishbone_io(compiler, modelname, model, to_model, from_model, bus)
+	else:
+		raise NotImplementedError("Unsupported bus")
+
+def _decode_args(desc, args, args_kw):
+	d = {}
+	argnames = set()
+	for param, value in zip_longest(desc, args):
+		if param is None:
+			raise TypeError("Too many arguments")
+		if isinstance(param, tuple):
+			name, default = param
+		else:
+			name, default = param, None
+		
+		# build the set of argument names at the same time
+		argnames.add(name)
+		
+		if value is None:
+			if default is None:
+				raise TypeError("No default value for parameter " + name)
+			else:
+				d[name] = default
+		else:
+			d[name] = value
+	for akw in args_kw:
+		if akw.arg not in argnames:
+			raise TypeError("Parameter " + akw.arg + " does not exist")
+		d[akw.arg] = akw.value
+	return d
+
+def gen_io(compiler, modelname, model, to_model, to_model_kw, from_model):
 	if model == Token:
-		return gen_df_io(compiler, modelname, to_model, from_model)
+		desc = [
+			"endpoint",
+			("value", ast.Name("None", ast.Load())),
+		]
+		args = _decode_args(desc, to_model, to_model_kw)
+		return _gen_df_io(compiler, modelname, args, from_model)
+	elif model == TRead or model == TWrite:
+		desc = [
+			"address",
+			("data", ast.Num(0)),
+			("sel", ast.Name("None", ast.Load())),
+			("busname", ast.Name("None", ast.Load()))
+		]
+		args = _decode_args(desc, to_model, to_model_kw)
+		return _gen_bus_io(compiler, modelname, model, args, from_model)
 	else:
 		raise NotImplementedError