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
Fa dev
check to see if the
hardware represented by
Fa dev
is still physically accessible at this time.
While the notion of accessible 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 children?''
which can better be answered by
device_get_children9.
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 determined.
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);
