bus_child_present(9)

NAME

bus_child_present - ask the bus driver to see if this device

is still
really present

SYNOPSIS

#include <sys/param.h>
#include <sys/bus.h>
#include <machine/bus.h>
#include <sys/rman.h>
#include <machine/resource.h>
int
bus_child_present(device_t dev);

DESCRIPTION

The bus_child_present() function requests that the parent

device driver
of dev check to see if the hardware represented by dev is

still physically accessible at this time. While the notion of accessi

ble varies
from bus to bus, generally hardware that is not accessible

cannot be
accessed via the bus_space*() methods that would otherwise

be used to
access the device.

This does not ask the question ``does this device have chil

dren?'' which
can better be answered by device_get_children(9).

RETURN VALUES

A zero return value indicates that the device is not present

in the system. A non-zero return value indicates that the device is

present in the
system, or that the state of the device cannot be deter

mined.

EXAMPLES

This is some example code. It only calls stop when the

dc(4) device is
actually present.

device_t dev;
dc_softc *sc;

sc = device_get_softc(dev);
if (bus_child_present(dev))

dc_stop(sc);

SEE ALSO

device(9), driver(9)

AUTHORS

This manual page was written by Warner Losh <imp@FreeB

SD.org>.

BSD March 27, 2003

BSD