| 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 |