driver(9)

NAME

driver - structure describing a device driver

SYNOPSIS

#include <sys/param.h>
#include <sys/bus.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 struct 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 */
        { 0, 0 }
};
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, 0, 0);

DESCRIPTION

Each driver in the kernel is described by a driver_t struc

ture. The
structure 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 asso

ciate with a
device instance. Each driver will implement one or more

sets of methods
(called interfaces). The example driver implements the

standard "driver"
interface and the fictitious "bogo" interface.

When a driver is registered with the system (by the DRIV

ER_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 in

stances 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 han

dler 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 June 16, 1998

BSD