Visit The New, Modern Unix Linux Community

Linux and UNIX Man Pages

Test Your Knowledge in Computers #416
Difficulty: Medium
JavaScript supports event-driven, functional, and imperative (including object-oriented and prototype-based) programming styles.
True or False?
Linux & Unix Commands - Search Man Pages

bus_child_present(9) [freebsd man page]

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 phys- ically 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_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 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

Check Out this Related Man Page

BUS_ACTIVATE_RESOURCE(9)				   BSD Kernel Developer's Manual				  BUS_ACTIVATE_RESOURCE(9)

NAME
bus_activate_resource, bus_deactivate_resource -- activate or deactivate a resource SYNOPSIS
#include <sys/param.h> #include <sys/bus.h> #include <machine/bus.h> #include <sys/rman.h> #include <machine/resource.h> int bus_activate_resource(device_t dev, int type, int rid, struct resource *r); int bus_deactivate_resource(device_t dev, int type, int rid, struct resource *r); DESCRIPTION
These functions activate or deactivate a previously allocated resource. In general, resources must be activated before they can be accessed by the driver so that the bus driver can map the resource into the devices space. The arguments are as follows: dev The device that requests ownership of the resource. Before allocation, the resource is owned by the parent bus. type The type of resource you want to allocate. It is one of: SYS_RES_IRQ for IRQs SYS_RES_DRQ for ISA DMA lines SYS_RES_IOPORT for I/O ports SYS_RES_MEMORY for I/O memory rid A pointer to a bus specific handle that identifies the resource being allocated. r A pointer to the struct resource returned by bus_alloc_resource(9). RETURN VALUES
Zero is returned on success, otherwise an error is returned. SEE ALSO
bus_alloc_resource(9), device(9), driver(9) AUTHORS
This manual page was written by Warner Losh <imp@FreeBSD.org>. BSD
March 28, 2003 BSD

Featured Tech Videos