device_get_state(9)

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 at

tached, 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_AT

TACHED.

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.

BSD June 16, 1998

BSD