Copyright (c) 1998 Doug Rabson
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$FreeBSD: head/share/man/man9/device_add_child.9 54032 1999-12-02 16:31:12Z n_hibma $
.Dd June 16, 1998 .Dt DEVICE_ADD_CHILD 9 .Os FreeBSD .Sh NAME .Nm device_add_child , .Nm device_add_child_ordered .Nd add a new device as a child of an existing device .Sh SYNOPSIS .Fd #include <sys/param.h> .Fd #include <sys/bus.h> .Ft int .Fn device_add_child "device_t dev" "const char *name" "int unit" "void *ivars" .Ft int .Fn device_add_child_ordered "device_t dev" "int order" "const char *name" "int unit" "void *ivars" .Sh DESCRIPTION
p Create a new child device of .Fa dev . The .Fa name and .Fa unit arguments specify the name and unit number of the device. If the name is unknown then the caller should pass .Dv NULL . If the unit is unknown then the caller should pass .Dv -1 and the system will choose the next available unit number. If there is any bus-specific data associated with the new child device (i.e. port numbers, irq settings etc.) then this should be supplied as the .Fa ivars argument.
p The name of the device is used to determine which drivers might be appropriate for the device. If a name is specified then only drivers of that name are probed. If no name is given then all drivers for the owning bus are probed.
p This allows busses which can uniquely identify device instances (such as PCI) to allow each driver to check each device instance for a match. For busses which rely on supplied probe hints where only one driver can have a change of probing the device, the driver name should specified as the device name.
p Normally unit numbers will be chosen automatically by the system and a unit number of .Dv -1 should be given. When a specific unit number is desired (e.g. for wiring a particular piece of hardware to a pre-configured unit number), that unit should be passed. If the specified unit number is already allocated, a new unit will be allocated and a diagnostic message printed.
p If the devices attached to a bus must be probed in a specific order (e.g. for the ISA bus some devices are sensitive to failed probe attempts of unrelated drivers and therefore must be probed first), the .Fa order argument of .Xr device_add_child_ordered 9 should be used to specify a partial ordering. The new device will be added before any existing device with a greater order. If .Xr device_add_child 9 is used, then the new child will be added as if its order was zero. .Sh RETURN VALUES The new device if successful, NULL otherwise. .Sh SEE ALSO .Xr device 9 .Sh AUTHORS This man page was written by .An Doug Rabson .