AUTOCONF(9) | Kernel Developer's Manual | AUTOCONF(9) |
autoconf
, config_search
,
config_found
, config_match
,
config_attach
,
config_attach_pseudo
,
config_detach
,
config_detach_children
,
config_deactivate
,
config_defer
,
config_interrupts
,
config_mountroot
,
config_pending_incr
,
config_pending_decr
,
config_finalize_register
—
#include <sys/param.h>
#include <sys/device.h>
#include <sys/errno.h>
cfdata_t
config_search
(device_t
parent, void *aux,
const struct cfargs
*);
device_t
config_found
(device_t
parent, void *aux,
cfprint_t print,
const struct cfargs
*);
int
config_match
(device_t
parent, cfdata_t
cf, void *aux);
int
config_probe
(device_t
parent, cfdata_t
cf, void *aux);
device_t
config_attach
(device_t
parent, cfdata_t
cf, void *aux,
cfprint_t print,
const struct cfargs
*);
device_t
config_attach_pseudo
(cfdata_t
cf);
int
config_detach
(device_t
dev, int
flags);
int
config_detach_children
(device_t
dev, int
flags);
int
config_deactivate
(device_t
dev);
int
config_defer
(device_t
dev, void
(*func)(device_t));
void
config_interrupts
(device_t
dev, void
(*func)(device_t));
void
config_mountroot
(device_t
dev, void
(*func)(device_t));
void
config_pending_incr
();
void
config_pending_decr
();
int
config_finalize_register
(device_t
dev, int
(*func)(device_t));
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(1). For a description of the config(1) “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 autoconfiguration, giving a unique address for each instance.
Several of the autoconfiguration functions take a strongly-typed
variadic list of arguments to pass information from driver autoconfiguration
functions to the kernel's autoconfiguration system. This list is constructed
using the CFARGS
() macro, like this example:
config_search(self, NULL, CFARGS(.search = mainbus_search, .iattr = "mainbus"));
Each tag is followed by a tag-specific value.
DIAGNOSTIC
option, this may result in an assertion
panic.If no arguments are to be passed, the special value
CFARGS_NONE
may be used in place of the
CFARGS
() macro.
config_search
(parent,
aux, cfargs)Performs indirect configuration of physical devices.
config_search
() iterates over all potential
children, calling the given search function If no search function is
specified, applies the potential child's match function instead. The
argument parent is the pointer to the parent's
device structure. If an interface attribute is specified, only potential
children eligible to attach to that interface attribute will be
consulted. If specified, the locators argument lists the locator values
for the device and are passed to the search function. The given
aux argument describes the device that has been
found and is simply passed on through the search function to the child.
config_search
() returns a pointer to the
configuration data that indicates the best-matched child or
NULL
otherwise.
The role of the search function is to call
config_probe
() for each potential child and call
config_attach
() for any positive matches. If no
search function is specified, 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
(parent,
aux, print,
cfargs)Performs direct configuration on a physical device.
config_found
() is called by the parent and in
turn calls the specified submatch function as determined by the
configuration table. The submatch function compares user-specified
locators from the machine description file against those specifying a
found device, calling config_match
() if they
match (including wildcard matching). If a submatch function is not
specified, then driver match functions are called directly. The argument
parent is the pointer to the parent's device
structure. If an interface attribute is specified, only potential
children eligible to attach to that interface attribute will be
consulted. If specified, the locators argument lists the locator values
for the found device and may be used by the submatch function and will
be recorded in the device structure of the child device. The given
aux argument describes the device that has been
found. config_found
() internally uses
config_search
(). The softc
structure for the matched device will be allocated, and the appropriate
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, otherwise 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
. If a device
handle is specified, that handle will be associated with the resulting
child device structure if a driver matches.
config_found
() returns a pointer to
the attached device's device structure if the
device is attached, NULL
otherwise. Most callers
can ignore this value, since the system will already have printed a
diagnostic.
config_match
(parent,
cf, aux)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_probe
(parent,
cf, aux)config_probe
() function returns a nonzero integer
to indicate a successful probe and a value of 0 otherwise. Unlike
config_match
(), the return value of
config_probe
() is not intended to reflect a
confidence value.config_attach
(parent,
cf, aux,
print, cfargs)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 a pointer to the
device structure. If unsuccessful, it returns
NULL
.
config_attach_pseudo
(cf)The caller is expected to allocate and fill the
cfdata_t object and pass it to
config_attach_pseudo
(). The content of that
object is similar to what is returned by
config_search
() for regular devices.
config_detach
(dev,
flags)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
context, allowing condition variables to be used while the device detaches
itself.config_detach_children
(dev,
flags)config_detach
() for each child of
dev, passing flags. If
detaching any child results in an error, the iteration will halt and any
remaining devices will not be detached.
config_detach_children
() returns zero if
successful and an error code otherwise.config_deactivate
(dev)config_deactivate
() is
called from interrupt context to immediately relinquish resources and
notify dependent kernel subsystems 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)config_interrupts
(dev,
func)config_mountroot
(dev,
func)config_pending_incr
()config_pending_decr
()config_finalize_register
(dev,
func)Registered functions are all executed until all of them return 0. The callbacks should return 0 to indicate they do not require to be called another time, but they should be aware that they still might be in case one of them returns 1.
August 7, 2021 | NetBSD 10.0 |