Copyright (c) 2003 M. Warner Losh
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$FreeBSD: head/share/man/man9/bus_child_present.9 112737 2003-03-28 07:09:17Z imp $
.Dd March 27, 2003 .Dt BUS_CHILD_PRESENT 9 .Os .Sh NAME .Nm bus_child_present .Nd Ask the bus driver to see if this device is still really present. .Sh SYNOPSIS n sys/param.h n sys/bus.h
p n machine/bus.h n sys/rman.h n machine/resource.h .Ft int .Fn bus_child_present "device_t dev" .Sh DESCRIPTION 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 acceessible cannot be accessed via the bus_space methods that would otherwise be used to acceess the device.
p This does not ask the question 'does this device have children?' which can better be answered by .Xr device_get_children 9 . .Sh 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. .Sh EXAMPLES This is some example code. It only calls stop when the dc device is actually present. d -literal device_t dev; dc_softc *sc; sc = device_get_softc(dev); if (bus_child_present(dev)) dc_stop(sc); .Ed .Sh SEE ALSO .Xr device 9 , .Xr driver 9 .Sh AUTHORS .An -nosplit This man page was written by .An Warner Losh Aq imp@FreeBSD.org .