parport_unregister_driver — deregister a parallel port device driver
| void parport_unregister_driver ( | struct parport_driver * drv ); | 
   This should be called by a parallel port device driver that
   has registered itself using parport_register_driver when it
   is about to be unloaded.
   
   When it returns, the driver's attach routine will no longer
   be called, and for each port that attach was called for, the
   detach routine will have been called.
   
   All the driver's attach and detach calls are guaranteed to have
   finished by the time this function returns.