Re: [PARPORT] Example Code

From: Andrew Hogue (hogue@cs.yorku.ca)
Date: Wed Mar 28 2001 - 16:25:40 EST

  • Next message: Tim Waugh: "Re: [PARPORT] Example Code"

    Hi again,

    I was following the example of using ppdev in order to access the parallel
    port device file, i.e.
      int fd;
      fd = open("/dev/parport0",O_RDWR);

    but fd is returned as -1 and when I check the errno, it says ENODEV. In
    the man pages, it says the following:

                  "pathname refers to a device special file and no
                  corresponding device exists. (This is a Linux ker-
                  nel bug - in this situation ENXIO must be
                  returned.) "

    Why would this be the case? Is there something that needs to be done
    before trying to open the /dev/parport0 in order to let my program access
    this file?

    Also I would really like to use the outb() and inb() functions since I
    need to set certain pins according to the protocol of my device, is there
    a way to do this with the ppdev interface?

    Thanks, 

    -- 
Andrew Hogue
York University
Toronto, ON
CANADA

    On Wed, 28 Mar 2001, Tim Waugh wrote:

    > On Tue, Mar 27, 2001 at 06:49:50PM -0500, Andrew Hogue wrote:
>
> > I am new to writing drivers and would like to see a few simple examples in
> > C so that I could write a parallel port driver (preferably kernel level)
> > to access some custom hardware of mine.  I know the protocol (i.e. which
> > bits to set on which pins) in order to access my hardware and how to power
> > it up etc...
>
> drivers/char/lp.c
> drivers/net/plip.c
> drivers/media/video/cpia_pp.c
> drivers/block/paride/*
>
> Also, do 'make htmldocs' and take a look in Documentation/DocBook.
>
> Tim.
> */
>

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