mcu: Add support for connecting to devices on a CAN bus

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

docs/Config_Reference.md

@@ -39,9 +39,16 @@ Configuration of the primary micro-controller.
 serial:
 #   The serial port to connect to the MCU. If unsure (or if it
 #   changes) see the "Where's my serial port?" section of the FAQ.
-#   This parameter must be provided.
+#   This parameter must be provided when using a serial port.
 #baud: 250000
 #   The baud rate to use. The default is 250000.
+#canbus_uuid:
+#   If using a device connected to a CAN bus then this sets the unique
+#   chip identifier to connect to. This value must be provided when using
+#   CAN bus for communication.
+#canbus_interface:
+#   If using a device connected to a CAN bus then this sets the CAN
+#   network interface to use. The default is 'can0'.
 #pin_map:
 #   This option may be used to enable Arduino pin name aliases. The
 #   default is to not enable the aliases.

klippy/extras/canbus_ids.py

@@ -0,0 +1,24 @@
+# Support for tracking canbus node ids
+#
+# Copyright (C) 2021  Kevin O'Connor <kevin@koconnor.net>
+#
+# This file may be distributed under the terms of the GNU GPLv3 license.
+
+class PrinterCANBus:
+    def __init__(self, config):
+        self.printer = config.get_printer()
+        self.ids = {}
+    def add_uuid(self, config, canbus_uuid, canbus_iface):
+        if canbus_uuid in self.ids:
+            raise config.error("Duplicate canbus_uuid")
+        new_id = len(self.ids)
+        self.ids[canbus_uuid] = new_id
+        return new_id
+    def get_nodeid(self, canbus_uuid):
+        if canbus_uuid not in self.ids:
+            raise self.printer.config_error("Unknown canbus_uuid %s"
+                                            % (canbus_uuid,))
+        return self.ids[canbus_uuid]
+
+def load_config(config):
+    return PrinterCANBus(config)

klippy/mcu.py

@@ -415,12 +415,20 @@ class MCU:
         if self._name.startswith('mcu '):
             self._name = self._name[4:]
         # Serial port
-        self._serialport = config.get('serial')
+        self._serial = serialhdl.SerialReader(self._reactor)
         self._baud = 0
+        self._canbus_iface = None
+        canbus_uuid = config.get('canbus_uuid', None)
+        if canbus_uuid is not None:
+            self._serialport = canbus_uuid
+            self._canbus_iface = config.get('canbus_interface', 'can0')
+            cbid = self._printer.load_object(config, 'canbus_ids')
+            cbid.add_uuid(config, canbus_uuid, self._canbus_iface)
+        else:
+            self._serialport = config.get('serial')
             if not (self._serialport.startswith("/dev/rpmsg_")
                     or self._serialport.startswith("/tmp/klipper_host_")):
                 self._baud = config.getint('baud', 250000, minval=2400)
-        self._serial = serialhdl.SerialReader(self._reactor)
         # Restarts
         restart_methods = [None, 'arduino', 'cheetah', 'command', 'rpi_usb']
         self._restart_method = 'command'
@@ -617,7 +625,12 @@ class MCU:
                 # Try toggling usb power
                 self._check_restart("enable power")
             try:
-                if self._baud:
+                if self._canbus_iface is not None:
+                    cbid = self._printer.lookup_object('canbus_ids')
+                    nodeid = cbid.get_nodeid(self._serialport)
+                    self._serial.connect_canbus(self._serialport, nodeid,
+                                                self._canbus_iface)
+                elif self._baud:
                     # Cheetah boards require RTS to be deasserted
                     # else a reset will trigger the built-in bootloader.
                     rts = (resmeth != "cheetah")