Using the serial port for GPIO.

[Scott Garman]

Has anyone here ever used the Linux serial port drivers as general 
purpose I/O? By that I mean not using the port for RS-232 protocol 
communications, but querying and setting the levels of individual pins 
on the port. This is for an embedded systems project I'm working on.

If I have no other options, my plan is to write a /proc kernel driver so 
user space programs can get access to this information, but I have a 
strong feeling that this kind of thing has been done many times before, 
and may even be possible with existing utilities that I just don't know 
about.

setserial, for example, allows you to configure the port and IRQ that a 
serial device is set to. I want something just a bit higher-level than 
that, to be able to read/set the RTS pin, for example.

The serial devices I'm working with are plain vanilla 16550 UARTs on 
common PC hardware.

Thanks,

Scott

PS - Information on doing the same thing via the parallel port would 
also be very relevant to me.

-- 
Scott Garman
sgarman at iname dot com