There are 2 distinctive inputs already coded in CE2 inputs for keyboard and joystick (see attached image).
All you need to do is to map desired joystick input to listed joystick inputs.
If you insist of making your own input, insert comma between "value_down = 1.0 value_up = 0.0"
so it looks like this:
"value_down = 1.0, value_up = 0.0"
rendering the final code as:
{down = device_commands.Smoke, up = device_commands.Smoke, cockpit_device_id = devices.GENERAL, value_down = 1.0, value_up = 0.0, name = _('Smoke toggle'), category = _('3-pos')},