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

NAME
     device_attach, device_detach, device_probe, device_probe_and_attach -- man-
     age device's connection to a device driver

SYNOPSIS
     #include <sys/param.h>
     #include <sys/bus.h>

     int
     device_attach(device_t dev);

     int
     device_detach(device_t dev);

     int
     device_probe(device_t dev);

     int
     device_probe_and_attach(device_t dev);

DESCRIPTION
     These  functions  manage  the relationship between a device and device dri-
     vers.

     device_probe() invokes the DEVICE_PROBE(9) method of each	suitable  driver
     and  to  find the driver with the best match for dev.  If a matching driver
     is found, dev is set to the DS_ALIVE state and zero is returned.  If dev is
     already attached to a device driver or has been  disabled	via  device_dis-
     able(9), then it will not be probed and -1 is returned.

     device_attach()  fully  attaches  a  device  driver  to dev.  This function
     prints a description of the device and invokes the DEVICE_ATTACH(9) method.
     If the DEVICE_ATTACH(9) method succeeds, dev  is  set  to	the  DS_ATTACHED
     state  and  zero  is  returned.   If  the	DEVICE_ATTACH(9)  method  fails,
     BUS_CHILD_DETACHED(9) is called and an error value is returned.

     If the device name and unit are disabled by a  hint,  device_attach()  dis-
     ables the device, demotes it to the DS_NOTPRESENT state, and returns ENXIO.
     The  device  retains its device name and unit and can be re-enabled via de-
     vctl(8).

     device_probe_and_attach() is a wrapper function around  device_probe()  and
     device_attach()  that  fully  initialises	a device.  If dev is already at-
     tached or disabled, device_probe_and_attach() leaves the  device  unchanged
     and  returns  zero.  Otherwise, device_probe() is used to identify a device
     driver for dev and device_attach() finalizes attaching the driver	to  dev.
     Device  drivers  should  generally use this function to initialize a device
     rather than direct calls to device_probe() and device_attach().

     device_detach() detaches the device driver from dev.  This function invokes
     the DEVICE_DETACH(9) method to tear down device driver state for  dev.   If
     the method fails, its error value is returned and dev remains attached.  If
     the method succeeds, otherwise, BUS_CHILD_DETACHED(9) is called, the device
     is  set  to  the DS_NOTPRESENT state, and zero is returned.  If a device is
     busy, device_detach() fails with EBUSY and leaving dev unchanged.

RETURN VALUES
     Zero is returned on success, otherwise an appropriate  error  is  returned.
     In  addition,  device_probe()  returns -1 if dev is disabled or already at-
     tached.

SEE ALSO
     devctl(8), BUS_CHILD_DETACHED(9), device(9),  DEVICE_ATTACH(9),  DEVICE_DE-
     TACH(9), DEVICE_PROBE(9), driver(9)

AUTHORS
     This manual page was written by Doug Rabson.

FreeBSD 15.1			February 5, 2025      DEVICE_PROBE_AND_ATTACH(9)
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