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 adriver_t
structure. 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 associate 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
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.