'\" te
.\"  Copyright (c) 2000, Sun Microsystems, Inc.  All Rights Reserved
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.  See the License for the specific language governing permissions and limitations under the License.
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.TH ddi_get_devstate 9F "13 August 1999" "SunOS 5.11" "Kernel Functions for Drivers"
.SH NAME
ddi_get_devstate \- Check device state
.SH SYNOPSIS
.LP
.nf
#include <sys/ddi.h> 
#include <sys/sunddi.h>

\fBddi_devstate_t\fR \fBddi_get_devstate\fR(\fBdev_info_t *\fR\fIdip\fR);
.fi

.SH INTERFACE LEVEL
.sp
.LP
Solaris DDI specific (Solaris DDI)
.SH PARAMETERS
.sp
.ne 2
.mk
.na
\fB\fIdip\fR \fR
.ad
.RS 8n
.rt  
Pointer to the device's \fBdev_info\fR structure
.RE

.SH DESCRIPTION
.sp
.LP
The \fBddi_get_devstate()\fR function returns a value indicating the state of
the device specified by \fB dip\fR, 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.
.SH RETURN VALUES
.sp
.ne 2
.mk
.na
\fB\fBDDI_DEVSTATE_OFFLINE\fR\fR
.ad
.RS 25n
.rt  
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.
.RE

.sp
.ne 2
.mk
.na
\fB\fBDDI_DEVSTATE_DOWN\fR\fR
.ad
.RS 25n
.rt  
 The device is online but unusable due to a fault.
.RE

.sp
.ne 2
.mk
.na
\fB\fBDDI_DEVSTATE_QUIESCED\fR\fR
.ad
.RS 25n
.rt  
 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.
.RE

.sp
.ne 2
.mk
.na
\fB\fBDDI_DEVSTATE_DEGRADED\fR\fR
.ad
.RS 25n
.rt  
 The device is online but only able to provide a partial or degraded service,
due to a fault.
.RE

.sp
.ne 2
.mk
.na
\fB\fBDDI_DEVSTATE_UP\fR\fR
.ad
.RS 25n
.rt  
 The device is online and fully operational.
.RE

.SH CONTEXT
.sp
.LP
The \fBddi_get_devstate()\fR function may be called from user, kernel, or
interrupt context.
.SH NOTES
.sp
.LP
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 \fBread\fR(9E) routine would return \fBEIO\fR).
.sp
.LP
Depending on the driver, some non-I/O operations (for example, calls to the
driver's \fBioctl\fR(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, \fBEAGAIN\fR).
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.
.SH SEE ALSO
.sp
.LP
\fBattach\fR(9E),  \fBioctl\fR(9E), \fBopen\fR(9E), \fBread\fR(9E),
\fBstrategy\fR(9E), \fBwrite\fR(9E), \fBddi_dev_report_fault\fR(9F)