[PARPORT] User level custom ECP protocols -- where do I start?

Greg Nelson (ghn@qtmsys.com)
Tue, 8 Feb 2000 15:14:10 -0500 (EST)

I'm embarking on a project which will require me to interface a Linux
box to some custom hardware (outside of my control) which uses a form
of IEEE-1284 ECP communications. (It is non-compliant in that it ONLY
supports ECP mode, not byte mode or nibble mode or anything else.)

I have a system set up with a bleeding edge (2.3.42) kernel, which
appears to have greatly enhanced ECP support relative to 2.2.x. I've
looked through the kernel sources and through the linux-parport
archives, and I haven't been able to figure out what to do next.
There are really two questions I have:

1) Can a "user mode" parallel port driver be written as an
   application, or does it have to be built as a kernel module in
   order to access and control the port? (If not, I'm pretty sure
   I've seen some of the module source code, so I can try to work from
   there, but the thought of debugging code within the kernel gives me
   the heebie-jeebies.)

2) If yes, are any of the following available, and can someone give me
   pointers to where to find them or what they might be called?

   A) Sample application code which manipulates the new /dev/parport
      device through ioctls or other means to read and write data over

   B) A list of exposed parport ioctls and what they do.

   C) A kernel source code file which implements the ioctls from which
      I can derive this (I don't know my way around the kernel source
      code hierarchy well enough to know where to look for this

I hope this is not too naive of a question, but most of the discussion
in the archive seems to be about 2.2 kernels and about building
modules to support various parallel port mass storage devices, so I
wasn't sure how to make the leap to where I'm going.

Greg Nelson

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