device_get_state, device_busy, device_unbusy, device_is_alive, device_is_attached — manipulate device

       This manual page was written by Doug Rabson.

Debian                                            June 16, 1998                              DEVICE_GET_STATE(9)

       The current state of a device is accessed by  calling  device_get_state()  which  returns  DS_NOTPRESENT,
       DS_ALIVE,  DS_ATTACHED  or  DS_BUSY  (described  in device(9)).  To test see if a device was successfully
       probed, call device_is_alive() which simply returns if the state is greater or  equal  to  DS_ALIVE.   To
       test  see  if  a  device was successfully attached, call device_is_attached() which simply returns if the
       state is greater or equal to DS_ATTACHED.

       Each device has a busy count which is incremented when  device_busy()  is  called  and  decremented  when
       device_unbusy() is called.  Both routines return an error if the device state is less than DS_ATTACHED.

       When  device_busy()  is  called  on  a device in the DS_ATTACHED state, the device changes to the DS_BUSY
       state.  When device_unbusy() is called and after decrementing, the busy count for the device is zero, the
       device changes to the DS_ATTACHED state.

       device_get_state,  device_busy,  device_unbusy,  device_is_alive,  device_is_attached — manipulate device
       state

device(9)

#include<sys/param.h>#include<sys/bus.h>device_state_tdevice_get_state(device_tdev);

       voiddevice_busy(device_tdev);

       voiddevice_unbusy(device_tdev);

       intdevice_is_alive(device_tdev);

       intdevice_is_attached(device_tdev);