autoconf(9)
- NetBSD Manual Pages
AUTOCONF(9) NetBSD Kernel Developer's Manual AUTOCONF(9)
NAME
autoconf, config_search, config_found_sm, config_found, config_match,
config_attach, config_detach, config_activate, config_deactivate,
config_defer, config_interrupts, config_pending_incr, config_pending_decr
-- autoconfiguration framework
SYNOPSIS
#include <sys/param.h>
#include <sys/device.h>
#include <sys/errno.h>
struct cfdata *
config_search(cfmatch_t func, struct device *parent, void *aux);
struct device *
config_found_sm(struct device *parent, void *aux, cfprint_t print,
cfmatch_t submatch);
struct device *
config_found(struct device *parent, void *aux, cfprint_t print);
int
config_match(struct device *parent, struct cfdata *cf, void *aux);
struct device *
config_attach(struct device *parent, struct cfdata *cf, void *aux,
cfprint_t print);
int
config_detach(struct device *dev, int flags);
int
config_activate(struct device *dev);
int
config_deactivate(struct device *dev);
int
config_defer(struct device *dev, void (*func)(struct device *));
void
config_interrupts(struct device *dev, void (*func)(struct device *));
void
config_pending_incr();
void
config_pending_decr();
DESCRIPTION
Autoconfiguration is the process of matching hardware devices with an
appropriate device driver. In its most basic form, autoconfiguration
consists of the recursive process of finding and attaching all devices on
a bus, including other busses.
The autoconfiguration framework supports direct configuration where the
bus driver can determine the devices present. The autoconfiguration
framework also supports indirect configuration where the drivers must
probe the bus looking for the presence of a device. Direct configuration
is preferred since it can find hardware regardless of the presence of
proper drivers.
The autoconfiguration process occurs at system bootstrap and is driven by
a table generated from a ``machine description'' file by config(8). For
a description of the config(8) ``device definition'' language, see
config(9).
Each device must have a name consisting of an alphanumeric string that
ends with a unit number. The unit number identifies an instance of the
driver. Device data structures are allocated dynamically during autocon-
figuration, giving a unique address for each instance.
FUNCTIONS
config_search(func, parent, aux)
Performs indirect configuration of physical devices.
config_search() iterates over all potential children, calling
the given function func for each one. If func is NULL,
config_search() applies each child's match function instead.
The argument parent is the pointer to the parent's device struc-
ture. The given aux argument describes the device that has been
found and is simply passed on through func to the child.
config_search() returns a pointer to the best-matched child or
NULL otherwise.
The role of func is to call the match function for each device
and call config_attach() for any positive matches. If func is
NULL, then the parent should record the return value from
config_search() and call config_attach() itself.
Note that this function is designed so that it can be used to
apply an arbitrary function to all potential children. In this
case callers may choose to ignore the return value.
config_found_sm(parent, aux, print, submatch)
Performs direct configuration on a physical device.
config_found_sm() is called by the parent and in turn calls the
submatch function to call the match function as determined by
the configuration table. If submatch is NULL, the driver match
functions are called directly. The argument parent is the
pointer to the parent's device structure. The given aux argu-
ment describes the device that has been found. The softc struc-
ture for the matched device will be allocated, and the appropri-
ate driver attach function will be called. If the device is
matched, the system prints the name of the child and parent
devices, and then calls the print function to produce additional
information if desired. If no driver takes a match, the same
print function is called to complain. The print function is
called with the aux argument and, if the matches failed, the
full name (including unit number) of the parent device, other-
wise NULL. The print function must return an integer value.
Two special strings, ``not configured'' and ``unsupported'' will
be appended automatically to non-driver reports if the return
value is UNCONF or UNSUPP respectively; otherwise the function
should return the value QUIET.
config_found_sm() returns a pointer to the attached device's
softc structure if the device is attached, NULL otherwise. Most
callers can ignore this value, since the system will already
have printed a diagnostic.
config_found(parent, aux, print)
This function is equivalent to calling config_found_sm(parent,
aux, print, submatch) with submatch set to NULL and is provided
for compatibility with older drivers.
config_match(parent, cf, aux)
Match a device. Invokes the drivers match function according to
the configuration table. The config_match() function returns a
nonzero integer indicating the confidence of supporting this
device and a value of 0 if the driver doesn't support the
device.
config_attach(parent, cf, aux, print)
Attach a found device. Allocates the memory for the softc
structure and calls the drivers attach function according to the
configuration table. If successful, config_attach() returns the
softc. If unsuccessful, it returns NULL.
config_detach(dev, flags)
Called by the parent to detach the child device. The second
argument flags contains detachment flags. Valid values are
DETACH_FORCE (force detachment (e.g., because of hardware
removal)) and DETACH_QUIET (do not print a notice).
config_detach() returns zero if successful and an error code
otherwise. config_detach() is always called from a thread con-
text, allowing ltsleep(9) to be called while the device detaches
itself.
config_activate(dev)
Called by the parent to activate the child device dev. It is
called to activate resources and initialise other kernel subsys-
tems (such as the network subsystem). config_activate() is
called from interrupt context after the device has been
attached.
config_deactivate(dev)
Called by the parent to deactivate the child device dev.
config_deactivate() is called from interrupt context to immedi-
ately relinquish resources and notify dependent kernel subsys-
tems that the device is about to be detached. At some later
point config_detach() will be called to finalise the removal of
the device.
config_defer(dev, func)
Called by the child to defer the remainder of its configuration
until all its parent's devices have been attached. At this
point, the function func is called with the argument dev.
config_interrupts(struct device *dev, void (*func)(struct device *))
Called by the child to defer the remainder of its configuration
until interrupts are enabled. At this point, the function func
is called with the argument dev.
config_pending_incr()
Increment the config_pending semaphore. It is used to account
for deferred configurations before mounting the root file sys-
tem.
config_pending_decr()
Decrement the config_pending semaphore. It is used to account
for deferred configurations before mounting the root file sys-
tem.
CODE REFERENCES
This section describes places within the NetBSD source tree where actual
code implementing or using the autoconfiguration framework can be found.
All pathnames are relative to /usr/src.
The autoconfiguration framework itself is implemented within the file
sys/kern/subr_autoconf.c. Data structures and function prototypes for
the framework are located in sys/sys/device.h.
SEE ALSO
config(8), config(9), driver(9)
HISTORY
Autoconfiguration first appeared in 4.1BSD. The autoconfiguration frame-
work was completely revised in 4.4BSD. The detach and activate/deacti-
vate interfaces appeared in NetBSD 1.5.
NetBSD 3.0 October 5, 2002 NetBSD 3.0
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