bus_read_ivar(9)

NAME

BUS_READ_IVAR, BUS_WRITE_IVAR - manipulate bus-specific de

vice 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