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NAME

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

SYNOPSIS

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

     device_state_t
     device_get_state(device_t dev);

     void
     device_busy(device_t dev);

     void
     device_unbusy(device_t dev);

     int
     device_is_alive(device_t dev);

     int
     device_is_attached(device_t dev);

DESCRIPTION

     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.

SEE ALSO

     device(9)

AUTHORS

     This manual page was written by Doug Rabson.