driver(9) - FreeBSD 15.1-RELEASE and Ports.quarterly Manual Pages

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DRIVER(9)		    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)
     };

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

DESCRIPTION
     Each driver in the kernel is described by a driver_t structure.  The struc-
     ture  contains  the  name of the device, a pointer to a list of methods, 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 in-
     stance.  Each driver will implement one or more sets of methods (called in-
     terfaces).  The example driver implements the standard  "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 dri-
     ver  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_IDEN-
     TIFY(9), DEVICE_PROBE(9), DEVICE_SHUTDOWN(9), DRIVER_MODULE(9)

HISTORY
     The driver framework first appeared in FreeBSD 2.2.7.

AUTHORS
     This manual page was written by Doug Rabson.

FreeBSD 15.1			 April 19, 2022 		       DRIVER(9)
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