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DEVICE_GET_STATE(9) | Kernel Developer's Manual | DEVICE_GET_STATE(9) |
NAME¶
device_get_state, device_busy, device_unbusy, device_is_alive, device_is_attached — manipulate device stateSYNOPSIS¶
#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 returnsDS_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.June 16, 1998 | Debian |