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device_identify(9) [debian man page]

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

NAME
DEVICE_IDENTIFY -- identify a device, register it SYNOPSIS
#include <sys/param.h> #include <sys/bus.h> void DEVICE_IDENTIFY(driver_t *driver, device_t parent); DESCRIPTION
The identify function for a device is only needed for devices on busses that cannot identify their children independently, e.g. the ISA bus. It is used to recognize the device (usually done by accessing non-ambiguous registers in the hardware) and to tell the kernel about it and thus creating a new device instance. BUS_ADD_CHILD(9) is used to register the device as a child of the bus. The device's resources (such as IRQ and I/O ports) are registered with the kernel by calling bus_set_resource() for each resource (refer to bus_set_resource(9) for more information). Since the device tree and the device driver tree are disjoint, the DEVICE_IDENTIFY() routine needs to take this into account. If you load and unload your device driver that has the identify routine, the child node has the potential for adding the same node multiple times unless specific measure are taken to preclude that possibility. EXAMPLES
The following pseudo-code shows an example of a function that probes for a piece of hardware and registers it and its resource (an I/O port) with the kernel. void foo_identify(driver_t *driver, device_t parent) { device_t child; retrieve_device_information; if (devices matches one of your supported devices && not already in device tree) { child = BUS_ADD_CHILD(parent, 0, "foo", -1); bus_set_resource(child, SYS_RES_IOPORT, 0, FOO_IOADDR, 1); } } SEE ALSO
BUS_ADD_CHILD(9), bus_set_resource(9), device(9), device_add_child(9), DEVICE_ATTACH(9), DEVICE_DETACH(9), DEVICE_PROBE(9), DEVICE_SHUTDOWN(9) AUTHORS
This manual page was written by Alexander Langer <alex@FreeBSD.org>. BSD
May 13, 2004 BSD

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

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 pass NULL. If the unit is unknown then the caller should pass -1 and the system will choose the next available unit num- ber. 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 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 speci- fied 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 par- tial 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. When adding a device in the context of DEVICE_IDENTIFY(9) routine, the device_find_child(9) routine should be used to ensure that the device has not already been added to the tree. Because the device name and devclass_t are associated at probe time (not child addition time), pre- vious 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 devices. Identify routines should use BUS_ADD_CHILD(9) instead of device_add_child(9). RETURN VALUES
The new device if successful, NULL otherwise. SEE ALSO
BUS_ADD_CHILD(9), device(9), device_find_child(9), DEVICE_IDENTIFY(9) AUTHORS
This manual page was written by Doug Rabson. BSD September 12, 2006 BSD
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