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

illumos DDI specific (illumos 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 possible.
If appropriate, it should return an error to its caller, indicating that
the device has failed (for example, a driver's read(9E) routine 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)

August 13, 1999 DDI_GET_DEVSTATE(9F)