diff --git a/software/glasgow/gateware/stream.py b/software/glasgow/gateware/stream.py
new file mode 100644
index 000000000..59f1bfcad
--- /dev/null
+++ b/software/glasgow/gateware/stream.py
@@ -0,0 +1,72 @@
+from amaranth.hdl import *
+from amaranth._utils import final
+from amaranth.lib import wiring
+from amaranth.lib.wiring import In, Out
+
+
+@final
+class Signature(wiring.Signature):
+    def __init__(self, payload_shape: 'ShapeLike', *, always_valid=False, always_ready=False):
+        Shape.cast(payload_shape)
+        self._payload_shape = payload_shape
+        self._always_valid = bool(always_valid)
+        self._always_ready = bool(always_ready)
+
+        super().__init__({
+            "payload": Out(payload_shape),
+            "valid": Out(1),
+            "ready": In(1)
+        })
+
+    # payload_shape intentionally not introspectable (for now)
+
+    @property
+    def always_valid(self):
+        return self._always_valid
+
+    @property
+    def always_ready(self):
+        return self._always_ready
+
+    def __eq__(self, other):
+        return (type(other) is type(self) and
+            other._payload_shape == self._payload_shape and
+            other.always_valid == self.always_valid and
+            other.always_ready == self.always_ready)
+
+    def create(self, *, path=None, src_loc_at=0):
+        return Interface(self, path=path, src_loc_at=1 + src_loc_at)
+
+    def __repr__(self):
+        always_valid_repr = "" if not self._always_valid else ", always_valid=True"
+        always_ready_repr = "" if not self._always_ready else ", always_ready=True"
+        return f"stream.Signature({self._payload_shape!r}{always_valid_repr}{always_ready_repr})"
+
+
+@final
+class Interface:
+    payload: Signal
+    valid: 'Signal | Const'
+    ready: 'Signal | Const'
+
+    def __init__(self, signature: Signature, *, path=None, src_loc_at=0):
+        if not isinstance(signature, Signature):
+            raise TypeError(f"Signature of stream.Interface must be a stream.Signature, not "
+                            f"{signature!r}")
+        self._signature = signature
+        self.__dict__.update(signature.members.create(path=path, src_loc_at=1 + src_loc_at))
+        if signature.always_valid:
+            self.valid = Const(1)
+        if signature.always_ready:
+            self.ready = Const(1)
+
+    @property
+    def signature(self):
+        return self._signature
+
+    @property
+    def p(self):
+        return self.payload
+
+    def __repr__(self):
+        return f"stream.Interface(payload={self.payload!r}, valid={self.valid!r}, ready={self.ready!r})"