toolhead: Add support for the M204 command

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

docs/G-Codes.md

@@ -15,6 +15,7 @@ Klipper supports the following standard G-Code commands:
 - Set position: `G92 [X<pos>] [Y<pos>] [Z<pos>] [E<pos>]`
 - Set speed factor override percentage: `M220 S<percent>`
 - Set extrude factor override percentage: `M221 S<percent>`
+- Set acceleration: `M204 S<value>`
 - Get extruder temperature: `M105`
 - Set extruder temperature: `M104 [T<index>] [S<temperature>]`
 - Set extruder temperature and wait: `M109 [T<index>] S<temperature>`

klippy/toolhead.py

@@ -238,6 +238,7 @@ class ToolHead:
         gcode = printer.lookup_object('gcode')
         gcode.register_command('SET_VELOCITY_LIMIT', self.cmd_SET_VELOCITY_LIMIT,
                                desc=self.cmd_SET_VELOCITY_LIMIT_help)
+        gcode.register_command('M204', self.cmd_M204)
     # Print time tracking
     def update_move_time(self, movetime):
         self.print_time += movetime
@@ -436,6 +437,10 @@ class ToolHead:
                    junction_deviation))
         self.printer.set_rollover_info("toolhead", "toolhead: %s" % (msg,))
         gcode.respond_info(msg)
+    def cmd_M204(self, params):
+        gcode = self.printer.lookup_object('gcode')
+        accel = gcode.get_float('S', params, above=0.)
+        self.max_accel = min(accel, self.config_max_accel)
 
 def add_printer_objects(printer, config):
     printer.add_object('toolhead', ToolHead(printer, config))