linuxconsole-dev

Re: 'Phys:' field for keyboards (and other input devices)

[Brad M. <bmi...@xm...>]

> Right now i am putting together a system which (among other) uses
> a userspace mechanism to determine the vt which it should bind
> keyboards to. for conveniance i am useing the hotplug interface
> and consider extending hotplug to return vt numbers. 

i wrote an app a while ago that put up "press 0" and "press 1" etc on each head and used the result to map keyboards. (it was in conjunction with a failed attempt to patch the kernel for multihead)

i looked a bit and couldn't find the source, but you get the idea.

one problem is that two usb keyboards would come up in a random order and you'd have to do this at every boot and every time keyboards were plugged/unplugged. not fun. do usb keyboards have a serial number? (dreaming i'm sure)

brad

Re: 'Phys:' field for keyboards (and other input devices)

[Vojtech P. <vo...@su...>]

On Fri, Sep 27, 2002 at 01:22:39PM -0600, Brad Midgley wrote:
> > Right now i am putting together a system which (among other) uses
> > a userspace mechanism to determine the vt which it should bind
> > keyboards to. for conveniance i am useing the hotplug interface
> > and consider extending hotplug to return vt numbers. 
> 
> i wrote an app a while ago that put up "press 0" and "press 1" etc on each head and used the result to map keyboards. (it was in conjunction with a failed attempt to patch the kernel for multihead)
> 
> i looked a bit and couldn't find the source, but you get the idea.
> 
> one problem is that two usb keyboards would come up in a random order and you'd have to do this at every boot and every time keyboards were plugged/unplugged. not fun. do usb keyboards have a serial number? (dreaming i'm sure)

No, but they have the "PHYS" value readable from either /dev/input/event
devices using an ioctl, or from /proc/bus/input/devices. This reflects
which connector on the USB Hub they're connected to.

-- 
Vojtech Pavlik
SuSE Labs

Re: 'Phys:' field for keyboards (and other input devices)

[Brad H. <bh...@bi...>]

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On Tue, 8 Oct 2002 18:33, Vojtech Pavlik wrote:
> No, but they have the "PHYS" value readable from either /dev/input/event
> devices using an ioctl, or from /proc/bus/input/devices. This reflects
> which connector on the USB Hub they're connected to.
#include <stdlib.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <asm/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdint.h>

#include <linux/input.h>


int main (int argc, char **argv) {

  int fd = -1;
  char phys[256]= "Unknown";

  /* ioctl() requires a file descriptor, so we check we got one, and then open 
it */
  if (argc != 2) {
    fprintf(stderr, "usage: %s event-device - probably /dev/input/event0\n", 
argv[0]);
    exit(1);
  }
  if ((fd = open(argv[1], O_RDONLY)) < 0) {
    perror("evdev open");
    exit(1);
  }

  /* suck out the name information
   * return value is the length of the physical path, for success
   * or -EFAULT for failure
   */
  if(ioctl(fd, EVIOCGPHYS(sizeof(phys)), phys) < 0) {
      perror("event ioctl");
  }

  printf("The device on %s says it's physical path is %s\n", argv[1], phys);

  close(fd);

  exit(0);
}

Brad
- -- 
http://linux.conf.au. 22-25Jan2003. Perth, Aust. I'm registered. Are you?
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