freebsd-skq/share/man/man9/device_get_state.9
2001-01-16 09:32:40 +00:00

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.\" Copyright (c) 1998 Doug Rabson
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.Dd June 16, 1998
.Dt DEVICE_GET_STATE 9
.Os FreeBSD
.Sh NAME
.Nm device_get_state ,
.Nm device_busy ,
.Nm device_unbusy ,
.Nm device_is_alive
.Nd manipulate device state
.Sh SYNOPSIS
.Fd #include <sys/param.h>
.Fd #include <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
.Pp
The current state of a device is accessed by calling
.Xr device_get_state 9
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
.Xr device_is_alive 9
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
.Xr device_busy 9
is called and decremented when
.Xr device_unbusy 9
is called. Both routines return an error if the device state is less
than
.Dv DS_ATTACHED .
.Pp
When
.Xr device_busy 9
is called on a device in the
.Dv DS_ATTACHED
state, the device changes to the
.Dv DS_BUSY
state.
When
.Xr device_unbusy 9
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 .