build.plat: add default_rst, to be used with default_clk.

diff --git a/nmigen/build/plat.py b/nmigen/build/plat.py
index ef39d23004c854c29f6ccbd6dfb3d79e5213efb3..f11dce63e0346f3629b047b34a7fc901d749f45a 100644 (file)
--- a/nmigen/build/plat.py
+++ b/nmigen/build/plat.py
@@ -21,6 +21,7 @@ class Platform(ResourceManager, metaclass=ABCMeta):
     resources   = abstractproperty()
     connectors  = abstractproperty()
     default_clk = None
+    default_rst = None
 
     def __init__(self):
         super().__init__(self.resources, self.connectors)