parport_find_number — find a parallel port by number
| struct parport * parport_find_number ( | int number ); | 
   This returns the parallel port with the specified number, or
   NULL if there is none.
   
   There is an implicit parport_get_port done already; to throw
   away the reference to the port that parport_find_number
   gives you, use parport_put_port.