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)