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AUTOCONF(9)                Kernel Developer's Manual               AUTOCONF(9)

NAME
     autoconf, config_search_loc, config_search_ia, config_found_sm_loc,
     config_found_ia, config_found, config_match, config_attach_loc,
     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 -- autoconfiguration
     framework

SYNOPSIS
     #include <sys/param.h>
     #include <sys/device.h>
     #include <sys/errno.h>

     cfdata_t
     config_search_loc(cfsubmatch_t func, device_t parent, const char *ia,
         const int *locs, void *aux);

     cfdata_t
     config_search_ia(cfsubmatch_t func, device_t parent, const char *ia,
         void *aux);

     device_t
     config_found_sm_loc(device_t parent, const char *ia, const int *locs,
         void *aux, cfprint_t print, cfsubmatch_t submatch);

     device_t
     config_found_ia(device_t parent, const char *ia, void *aux,
         cfprint_t print);

     device_t
     config_found(device_t parent, void *aux, cfprint_t print);

     int
     config_match(device_t parent, cfdata_t cf, void *aux);

     device_t
     config_attach_loc(device_t parent, cfdata_t cf, const int *locs,
         void *aux, cfprint_t print);

     device_t
     config_attach(device_t parent, cfdata_t cf, void *aux, cfprint_t print);

     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));

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(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.

FUNCTIONS
     config_search_loc(func, parent, ia, locs, aux)
              Performs indirect configuration of physical devices.
              config_search_loc() iterates over all potential children,
              calling the given function func for each one.  If func is NULL,
              config_search_loc() applies each child's match function instead.
              The argument parent is the pointer to the parent's device
              structure.  The argument ia is the interface attribute on which
              the potential children should attach.  It can be NULL, in which
              case all children attaching to any attribute are considered.
              The locs argument lists the locator values for the device and
              are passed to function func.  The given aux argument describes
              the device that has been found and is simply passed on through
              func to the child.  config_search_loc() 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_loc() for any positive matches.  If func
              is NULL, then the parent should record the return value from
              config_search_loc() and call config_attach_loc() 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_search_ia(func, parent, ia, aux)
              This function is equivalent to calling config_search_loc(func,
              parent, ia, locs, aux) with locs set to NULL.

     config_found_sm_loc(parent, ia, locs, aux, print, submatch)
              Performs direct configuration on a physical device.
              config_found_sm_loc() 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 argument ia is
              the name of the interface attribute on which the child will
              attach, per config(5) syntax.  The argument locs lists the
              locator values for the device.  The given aux argument describes
              the device that has been found.  config_found_sm_loc()
              internally uses config_search_loc(), passing on submatch, ia,
              locs and aux.  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.

              config_found_sm_loc() 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_ia(parent, ia, aux, print)
              This function is equivalent to calling
              config_found_sm_loc(parent, ia, locs, aux, print, submatch) with
              locs and submatch set to NULL.  It is provided for better source
              code readability with locator-less device buses.

     config_found(parent, aux, print)
              This function is equivalent to calling
              config_found_sm_loc(parent, ia, locs, aux, print, submatch) with
              ia, locs and submatch set to NULL and is provided for
              compatibility with older drivers.  New code should either make
              the interface attribute explicit or prefer an indirect method
              based on config_search_loc().

     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_loc(parent, cf, locs, 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_loc() returns
              the softc.  If unsuccessful, it returns NULL.

     config_attach(parent, cf, aux, print)
              This function is equivalent to calling config_attach_loc(parent,
              cf, locs, aux, print) with locs set to NULL.

     config_attach_pseudo(cf)
              Create an instance of a pseudo-device driver.  config(5) syntax
              allows the creation of pseudo-devices from which regular
              device_t instances can be created.  Such objects are similar to
              the devices that attach at the root of the device tree.

              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_loc() for
              regular devices.

     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
              context, allowing condition variables to be used while the
              device detaches itself.

     config_detach_children(dev, flags)
              Iterate through all attached devices, calling 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)
              Called by the parent to deactivate the child device 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)
              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(dev, func)
              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_mountroot(dev, func)
              Called by the child to defer the remainder of its configuration
              until the root file system is mounted.  At this point, the
              function func is called with the argument dev.  This is used for
              devices that need to load firmware image from a mounted file
              system.

     config_pending_incr()
              Increment the config_pending semaphore.  It is used to account
              for deferred configurations before mounting the root file
              system.

     config_pending_decr()
              Decrement the config_pending semaphore.  It is used to account
              for deferred configurations before mounting the root file
              system.

     config_finalize_register(dev, func)
              Register a function to be called after all real devices have
              been found.

              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.

CODE REFERENCES
     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(1), config(5), condvar(9), config(9), driver(9)

HISTORY
     Autoconfiguration first appeared in 4.1BSD.  The autoconfiguration
     framework was completely revised in 4.4BSD.  The detach and deactivate
     interfaces appeared in NetBSD 1.5.

NetBSD 7.1.2                   February 17, 2012                  NetBSD 7.1.2