Create a new child device of
arguments specify the name and unit number of the device.
If the name is unknown then the caller should pass
If the unit is unknown then the caller should pass
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.
In any event, only the name of the device is stored so that one may
safely unload/load a driver bound to that name.
This allows busses which can uniquely identify device instances (such
as PCI) to allow each driver to check each device instance for a
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
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
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),
should be used to specify a partial ordering.
The new device will be added before any existing device with a greater
is used, then the new child will be added as if its order was zero.
When adding a device in the context of
routine should be used to ensure that the device has not already been
added to the tree.
Because the device name and
are associated at probe time (not child addition time), previous
instances of the driver (say in a module that was later unloaded) may
have already added the instance.
Authors of bus drivers must likewise be careful when adding children
when they are loaded and unloaded to avoid duplication of children
Identify routines should use