NAME
device_add_child,
device_add_child_ordered —
add a new device as a child of an
existing device
SYNOPSIS
#include
<sys/param.h>
#include <sys/bus.h>
device_t
device_add_child(device_t
dev, const char
*name, int
unit);
device_t
device_add_child_ordered(device_t
dev, int order,
const char *name,
int unit);
DESCRIPTION
Create a new child device of dev. The name and unit arguments specify the name and unit number of the device. If the name is unknown then the caller should passNULL. If the unit is unknown then the
caller should pass -1 and the system will choose the
next available unit number.
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.
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 chance of probing the device, the driver name should be specified as the device name.
Normally unit numbers will be chosen automatically by the system
and a unit number of -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.
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 order argument of
device_add_child_ordered()
should be used to specify a partial ordering. The new device will be added
before any existing device with a greater order. If
device_add_child()
is used, then the new child will be added as if its order was zero.
RETURN VALUES
The new device if successful, NULL otherwise.
SEE ALSO
AUTHORS
This man page was written by Doug Rabson.