ddi_get_devstate(9F) Kernel Functions for Drivers ddi_get_devstate(9F)
NAME
ddi_get_devstate - Check device state
SYNOPSIS
#include <sys/ddi.h>
#include <sys/sunddi.h>
ddi_devstate_t ddi_get_devstate(dev_info_t *dip);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI)
PARAMETERS
dip Pointer to the device's dev_info structure
DESCRIPTION
The ddi_get_devstate() function returns a value indicating the state of the device specified by dip, as derived from the configuration
operations that have been performed on it (or on the bus on which it resides) and any fault reports relating to it.
RETURN VALUES
DDI_DEVSTATE_OFFLINE
The device is offline. In this state, the device driver is not attached, nor will it be attached automatically. The device cannot be
used until it is brought online.
DDI_DEVSTATE_DOWN
The device is online but unusable due to a fault.
DDI_DEVSTATE_QUIESCED
The bus on which the device resides has been quiesced. This is not a fault, but no operations on the device should be performed while
the bus remains quiesced.
DDI_DEVSTATE_DEGRADED
The device is online but only able to provide a partial or degraded service, due to a fault.
DDI_DEVSTATE_UP
The device is online and fully operational.
CONTEXT
The ddi_get_devstate() function may be called from user, kernel, or interrupt context.
NOTES
A device driver should call this function to check its own state at each major entry point, and before committing resources to a requested
operation. If a driver discovers that its device is already down, it should perform required cleanup actions and return as soon as possi-
ble. If appropriate, it should return an error to its caller, indicating that the device has failed (for example, a driver's read(9E) rou-
tine would return EIO).
Depending on the driver, some non-I/O operations (for example, calls to the driver's ioctl(9E) routine) may still succeed; only functions
which would require fully accessible and operational hardware will necessarily fail. If the bus on which the device resides is quiesced,
the driver may return a value indicating the operation should be retried later (for example, EAGAIN). Alternatively, for some classes of
device, it may be appropriate for the driver to enqueue the operation and service it once the bus has been unquiesced. Note that not all
busses support the quiesce/unquiesce operations, so this value may never be seen by some drivers.
SEE ALSO
attach(9E), ioctl(9E), open(9E), read(9E), strategy(9E), write(9E), ddi_dev_report_fault(9F)
SunOS 5.10 13 August 1999 ddi_get_devstate(9F)