freebsd man page for bus_read_ivar

BUS_READ_IVAR(9)					   BSD Kernel Developer's Manual					  BUS_READ_IVAR(9)

NAME
     BUS_READ_IVAR, BUS_WRITE_IVAR -- manipulate bus-specific device instance variables

SYNOPSIS
     #include <sys/param.h>
     #include <sys/bus.h>

     int
     BUS_READ_IVAR(device_t dev, device_t child, int index, uintptr_t *result);

     int
     BUS_WRITE_IVAR(device_t dev, device_t child, int index, uintptr_t value);

DESCRIPTION
     These two methods manage a bus specific set of instance variables of a child device.  The intention is that each different type of bus
     defines a set of appropriate instance variables (such as ports and irqs for ISA bus etc.)

     This information could be given to the child device as a struct but that makes it hard for a bus to add or remove variables without forcing
     an edit and recompile for all drivers which may not be possible for vendor supplied binary drivers.

RETURN VALUES
     Zero is returned on success, otherwise an appropriate error is returned.

SEE ALSO
     device(9), driver(9)

AUTHORS
     This manual page was written by Doug Rabson.

BSD
								   June 16, 1998							       BSD