Disable mouse or touchpad in xorg

Update: Apparently figuring out how to disable x input devices like mice, keyboards and touch pads is hard to find on the search engines, so I'm updating the post to make it more findable. (This post was originally called "Ubuntu karmic: 3dconnexion Space Navigator and xorg", but I just helped a friend of mine disable his EEE PC's elantech touch pad, and realized that the solution is general purpose.)

My friend always uses an external mouse with his laptop, and accidentally brushes the touch pad when he's typing. So he wanted to find a way to shut off the touch pad.

In Ubuntu Karmic Koala (9.10), xorg now autodetects my 3dConnexion Space Navigator and uses its events for mouse X and Y, which is not what I want.

I just discovered xinput, though, which is extremely cool. Thanks Philip Langdale and Frederic Lepied for writing it!

root@lg1:~# xinput list
...
"3Dconnexion SpaceNavigator"    id=9    [XExtensionPointer]
        Type is MOUSE
        Num_buttons is 5
        Num_axes is 6
        Mode is Relative
        Motion_buffer is 256
        Axis 0 :
                Min_value is -1
                Max_value is -1
                Resolution is 1
        Axis 1 :
                Min_value is -1
                Max_value is -1
                Resolution is 1
        Axis 2 :
                Min_value is -1
                Max_value is -1
                Resolution is 1
        Axis 3 :
                Min_value is -1
                Max_value is -1
                Resolution is 1
        Axis 4 :
                Min_value is -1
                Max_value is -1
                Resolution is 1
        Axis 5 :
                Min_value is -1
                Max_value is -1
                Resolution is 1


root@lg1:~# xinput list-props "3Dconnexion SpaceNavigator"
Device '3Dconnexion SpaceNavigator':
        Device Enabled (93):    1
        Evdev Reopen Attempts (227):    10
        Evdev Axis Inversion (228):     0, 0
        Evdev Axis Calibration (229):
        Evdev Axes Swap (230):  0
        Evdev Middle Button Emulation (231):    2
        Evdev Middle Button Timeout (232):      50
        Evdev Wheel Emulation (233):    0
        Evdev Wheel Emulation Axes (234):       0, 0, 4, 5
        Evdev Wheel Emulation Inertia (235):    10
        Evdev Wheel Emulation Timeout (236):    200
        Evdev Wheel Emulation Button (237):     4
        Evdev Drag Lock Buttons (238):  0

root@lg1:~# xinput get-feedbacks "3Dconnexion SpaceNavigator"
1 feedback class
PtrFeedbackClass id=0
        accelNum is 2
        accelDenom is 1
        threshold is 4

root@lg1:~# xinput set-ptr-feedback "3Dconnexion SpaceNavigator" 4 8 1  # very sensitive X pointer
root@lg1:~# xinput set-ptr-feedback "3Dconnexion SpaceNavigator" 4 1 8  # much less sensitive.

The threshold parameter doesn't seem to do anything.

Ah, here's the magic to make it stop influencing the pointer:

root@lg1:~# xinput set-int-prop "3Dconnexion SpaceNavigator" 93 8 0  # property 93 from list-props

Also works as:

root@lg1:~# xinput set-int-prop "3Dconnexion SpaceNavigator" "Device Enabled" 8 0
root@lg1:~# xinput set-int-prop "3Dconnexion SpaceNavigator" "Device Enabled" 8 1  # reenable

Unfortunately, I don't see any way to re-zero if it drifts (often happens when they're cold or hot or brand new), or turn on the LED. Here's C code to do it, though:

#include <sys/ioctl.h>
#include <error.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <linux/input.h>

main(int argc, char **argv) {
  
  int fd;
  int retval;
  struct input_event ev; /* the event */

  if (argc != 3) {
    printf("Usage: %s device 1|0\n", argv[0]);
    exit(2);
  }

  if ((fd = open(argv[1], O_WRONLY)) < 0) {
      perror("opening the file you specified");
      exit(1);
  }
 
  ev.type = EV_LED;
  ev.code = LED_MISC;
  ev.value = (argv[2][0] == '1') ? 1:0;
  write(fd, &ev, sizeof(struct input_event));
}