driver(9) [freebsd man page]

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

NAME

     driver -- structure describing a device driver

SYNOPSIS

     #include <sys/param.h>
     #include <sys/kernel.h>
     #include <sys/bus.h>
     #include <sys/module.h>

     static int foo_probe(device_t);
     static int foo_attach(device_t);
     static int foo_detach(device_t);
     static int foo_frob(device_t, int, int);
     static int foo_twiddle(device_t, char *);

     static device_method_t foo_methods[] = {
	     /* Methods from the device interface */
	     DEVMETHOD(device_probe,	     foo_probe),
	     DEVMETHOD(device_attach,	     foo_attach),
	     DEVMETHOD(device_detach,	     foo_detach),

	     /* Methods from the bogo interface */
	     DEVMETHOD(bogo_frob,	     foo_frob),
	     DEVMETHOD(bogo_twiddle,	     foo_twiddle),

	     /* Terminate method list */
	     DEVMETHOD_END
     };

     static driver_t foo_driver = {
	     "foo",
	     foo_methods,
	     sizeof(struct foo_softc)
     };

     static devclass_t foo_devclass;

     DRIVER_MODULE(foo, bogo, foo_driver, foo_devclass, NULL, NULL);

DESCRIPTION

     Each driver in the kernel is described by a driver_t structure.  The structure contains the name of the device, a pointer to a list of meth-
     ods, an indication of the kind of device which the driver implements and the size of the private data which the driver needs to associate
     with a device instance.  Each driver will implement one or more sets of methods (called interfaces).  The example driver implements the stan-
     dard "driver" interface and the fictitious "bogo" interface.

     When a driver is registered with the system (by the DRIVER_MODULE macro, see DRIVER_MODULE(9)), it is added to the list of drivers contained
     in the devclass of its parent bus type.  For instance all PCI drivers would be contained in the devclass named "pci" and all ISA drivers
     would be in the devclass named "isa".  The reason the drivers are not held in the device object of the parent bus is to handle multiple
     instances of a given type of bus.	The DRIVER_MODULE macro will also create the devclass with the name of the driver and can optionally call
     extra initialisation code in the driver by specifying an extra module event handler and argument as the last two arguments.

SEE ALSO

     devclass(9), device(9), DEVICE_ATTACH(9), DEVICE_DETACH(9), DEVICE_IDENTIFY(9), DEVICE_PROBE(9), DEVICE_SHUTDOWN(9), DRIVER_MODULE(9)

AUTHORS

     This manual page was written by Doug Rabson.

BSD
								 November 22, 2011							       BSD

Check Out this Related 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

Linux and UNIX Man Pages

driver(9) [freebsd man page]

Check Out this Related Man Page