man pages section 9: DDI and DKI Kernel Functions

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Updated: July 2014
 
 

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 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)