parport_claim — claim access to a parallel port device
| int parport_claim ( | struct pardevice * dev ); | 
   This function will not block and so can be used from interrupt
   context.  If parport_claim succeeds in claiming access to
   the port it returns zero and the port is available to use.  It
   may fail (returning non-zero) if the port is in use by another
   driver and that driver is not willing to relinquish control of
   the port.