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|man pages section 9: DDI and DKI Kernel Functions Oracle Solaris 10 1/13 Information Library|
- Check device state
#include <sys/ddi.h> #include <sys/sunddi.h> ddi_devstate_t ddi_get_devstate(dev_info_t *dip);
Solaris DDI specific (Solaris DDI)
Pointer to the device's dev_info structure
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.
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.
The device is online but unusable due to a fault.
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.
The device is online but only able to provide a partial or degraded service, due to a fault.
The device is online and fully operational.
The ddi_get_devstate() function may be called from user, kernel, or interrupt context.
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.