NAME

       ieee1284_get_irq_fd, ieee1284_clear_irq - interrupt notification

SYNOPSIS

       #include <ieee1284.h>

       int ieee1284_get_irq_fd(struct parport *port);

       int ieee1284_clear_irq(struct parport *port, unsigned int *count);

DESCRIPTION

       If the port has a configured interrupt line and the port type supports interrupt
       notification, it is possible to obtain a file descriptor that may be used for select(2) or
       poll(2). Any event (readable, writable or exception) means that an interrupt has been
       triggered. No operations other than select or poll may be performed on the file
       descriptor.

       The port must be open in order to call ieee1284_get_irq_fd, and must be claimed when using
       select or poll.

       The caller must not close the file descriptor, and may not use it at all when the port is
       not claimed.

       When an interrupt has been detected, the caller must call ieee1284_clear_irq to clear the
       interrupt condition, at which point the number of interrupts raised can be obtained by
       supplying a non-NULL count.

RETURN VALUE

       For ieee1284_get_irq_fd: If the return value is negative then it is an error code listed
       below. Otherwise it is a valid file descriptor.

       E1284_NOTAVAIL
           No such file descriptor is available.

       E1284_INVALIDPORT
           The port parameter is invalid (for instance, perhaps the port is not open).

       For ieee1284_clear_irq:

       E1284_OK
           The interrupt has been cleared. If count was not NULL the count of interrupts has been
           atomically stored to count and reset.

       E1284_NOTAVAIL
           The count parameter was not NULL but interrupt counting is not supported on this type
           of port. The interrupt has been cleared.

       E1284_SYS
           There was a problem clearing the interrupt.

       E1284_INVALIDPORT
           The port parameter is invalid (for instance, perhaps the port is not claimed).

AUTHOR

       Tim Waugh <twaugh@redhat.com>
           Author.

COPYRIGHT

       Copyright © 2001-2003 Tim Waugh

                                            09/18/2007                     IEEE1284_GET_IRQ_FD(3)