Okay, so I can't use any of the standard serial ports for my needs as ttyS0 and ttyS2 don't have any control signals (only TD and RD) and ttyS1's control singals are all in use for other things when in DC mode.

I notice that there is "tuner level" and "tuner signal" on pins 4 and 3 of the sled connector (pins 1 and 2 of the tuner connector) respectively.

Are these both inputs to the Empeg and is it possible to read either of these using ioctl? If so, what would the code look like (as in, what is the name of the device and what is the name of the request argument to ioctl)?