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BUS_CHILD_PRESENT(9)	 BSD Kernel Developer's	Manual	  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 physi-
     cally accessible at this time.  While the notion of accessible varies
     from bus to bus, generally	hardware that is not accessible	cannot be ac-
     cessed via	the bus_space*() methods that would otherwise be used to ac-
     cess the device.

     This does not ask the question "does this device have children?" 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 sys-
     tem.  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);

SEE ALSO
     device(9),	driver(9)

AUTHORS
     This manual page was written by Warner Losh <imp@FreeBSD.org>.

BSD				March 27, 2003				   BSD

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | EXAMPLES | SEE ALSO | AUTHORS

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