diff --git a/host/dmctl/.gitignore b/host/dmctl/.gitignore
new file mode 100644
index 0000000..e689877
--- /dev/null
+++ b/host/dmctl/.gitignore
@@ -0,0 +1,3 @@
+__pycache__/
+
+*.pyc
diff --git a/host/dmctl/__init__.py b/host/dmctl/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/host/dmctl/commands.py b/host/dmctl/commands.py
new file mode 100644
index 0000000..084b84d
--- /dev/null
+++ b/host/dmctl/commands.py
@@ -0,0 +1,57 @@
+
+from typing import *
+
+from .connection import *
+
+
+def get_device_info(conn: DmjDevice) -> int:
+    return 0
+
+
+def get_mode_info(conn: DmjDevice, mode: Optional[int]) -> int:
+    return 0
+
+
+def set_mode(conn: DmjDevice, mode: int) -> int:
+    return 0
+
+
+# ---
+
+
+def uart_hw_flowctl_get(conn: DmjDevice) -> int:
+    return 0
+
+
+def uart_hw_flowctl_set(conn: DmjDevice, v: bool) -> int:
+    return 0
+
+
+# ---
+
+
+def tempsensor_get(conn: DmjDevice) -> int:
+    return 0
+
+
+def tempsensor_set(conn, v: int) -> int:
+    return 0
+
+
+# ---
+
+
+def jtag_scan(conn) -> int:
+    return 0
+
+
+# ---
+
+
+def sump_overclock_get(conn) -> int:
+    return 0
+
+
+def sump_overclock_set(conn, v: int) -> int:
+    return 0
+
diff --git a/host/dmctl/connection.py b/host/dmctl/connection.py
new file mode 100644
index 0000000..84883b7
--- /dev/null
+++ b/host/dmctl/connection.py
@@ -0,0 +1,111 @@
+
+from __future__ import annotations
+
+import os
+
+import abc
+from typing import *
+
+# TODO: EVERYTHING
+# * implement connecting to a device
+# * implement lower-level device commands
+# * implement device commands
+
+
+class DevConn(abc.ABC):
+    def read(self, nb: int) -> bytes:
+        raise NotImplementedError()
+
+    def write(self, b: bytes):
+        raise NotImplementedError()
+
+    def __enter__(self):
+        raise NotImplementedError()
+
+    def __exit__(self, type, value, tb):
+        raise NotImplementedError()
+
+
+class UsbConn(DevConn):
+    def try_find() -> Optional[UsbConn]:
+        return None
+
+    def is_usbdev_path(conn: str) -> bool:
+        return None
+
+    def try_open(conn: str) -> Union[UsbConn, str]:
+        return "Could not open USB device '%s'" % conn
+
+
+    def __init__(self):
+        pass
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, type, value, tb):
+        pass
+
+
+class ChardevConn(DevConn):
+    def try_find() -> Optional[ChardevConn]:
+        return None
+
+    def is_chardev_path(conn: str) -> bool:
+        return None
+
+    def try_open(conn: str) -> Union[ChardevConn, str]:
+        return "Could not open character device '%s'" % conn
+
+
+    def __init__(self, fd):
+        self._fd = fd
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, type, value, tb):
+        os.close(self._fd)
+        self._fd = -1
+
+
+class DmjDevice:
+    def __init__(self, conn: DevConn):
+        self._conn = conn
+
+    def __enter__(self):
+        self._conn.__enter__()
+        return self
+
+    def __exit__(self, type, value, tb):
+        self._conn.__exit__(type, value, tb)
+
+
+def connect(conn: Optional[str]) -> Union[DmjDevice, str]:
+    if conn is None:
+        attempt = ChardevConn.try_find()
+        if attempt is not None:
+            return DmjDevice(attempt)
+
+        attempt = UsbConn.try_find()
+        if attempt is not None:
+            return DmjDevice(attempt)
+
+        return "no device specified, and none could be found"
+
+    if ChardevConn.is_chardev_path(conn):
+        attempt = ChardevConn.try_open(conn)
+        if isinstance(attempt, str):
+            return attempt
+        else:
+            return DmjDevice(attempt)
+
+    if UsbConn.is_usbdev_path(conn):
+        attempt = UsbConn.try_open(conn)
+        if isinstance(attempt, str):
+            return attempt
+        else:
+            return DmjDevice(attempt)
+
+    return "connection string '%s' not recognised" % conn
+