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.\" $FreeBSD: src/share/man/man9/device_get_state.9,v 1.3.2.5 2001/12/17 11:30:18 ru Exp $
.\"
.Dd June 16, 1998
.Dt DEVICE_GET_STATE 9
.Os
.Sh NAME
.Nm device_get_state ,
.Nm device_busy ,
.Nm device_unbusy ,
.Nm device_is_alive
.Nd manipulate device state
.Sh SYNOPSIS
.In sys/param.h
.In sys/bus.h
.Ft device_state_t
.Fn device_get_state "device_t dev"
.Ft void
.Fn device_busy "device_t dev"
.Ft void
.Fn device_unbusy "device_t dev"
.Ft int
.Fn device_is_alive "device_t dev"
.Sh DESCRIPTION
The current state of a device is accessed by calling
.Fn device_get_state
which returns
.Dv DS_NOTPRESENT ,
.Dv DS_ALIVE ,
.Dv DS_ATTACHED
or
.Dv DS_BUSY
(described in
.Xr device 9 ) .
To test see if a device was successfully probed, call
.Fn device_is_alive
which simply returns if the state is greater or equal to
.Dv DS_ALIVE .
.Pp
Each device has a busy count which is incremented when
.Fn device_busy
is called and decremented when
.Fn device_unbusy
is called.  Both routines return an error if the device state is less
than
.Dv DS_ATTACHED .
.Pp
When
.Fn device_busy
is called on a device in the
.Dv DS_ATTACHED
state, the device changes to the
.Dv DS_BUSY
state.
When
.Fn device_unbusy
is called and after decrementing, the busy count for the device is
zero, the device changes to the
.Dv DS_ATTACHED
state.
.Sh SEE ALSO
.Xr device 9
.Sh AUTHORS
This man page was written by
.An Doug Rabson .