ddi_get_devstate(9f) [sunos man page]

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)

quiesce(9E)							Driver Entry Points						       quiesce(9E)

NAME

       quiesce - quiesce a device

SYNOPSIS

       #include <sys/ddi.h>
       #include <sys/sunddi.h>

       int prefixquiesce(dev_info_t *dip);

       int ddi_quiesce_not_needed(dev_info_t *dip);

INTERFACE LEVEL

       Solaris DDI specific (Solaris DDI)

PARAMETERS

       dip    A pointer to the device's dev_info structure.

DESCRIPTION

       The  quiesce() function quiesces a device so that the device no longer generates interrupts, modifies or accesses memory. The driver should
       reset the device to a hardware state from which the device can be correctly configured by the driver's attach() routine	without  a  system
       power cycle or being configured by the firmware. For devices with a defined reset state configuration, the driver should return that device
       to that state as part of the quiesce operation. Fast Reboot, where firmware is bypassed when booting to a new OS image, is such a case.

       quiesce() is only called for an attached device instance as one of the final operations of a reboot sequence, and no other  thread  can	be
       active  for this device. The system guarantees that no other driver entry point is active or invoked while quiesce() is invoked. The system
       also guarantees that no timeout or taskq is invoked. The system is single-threaded and can not be interrupted. Therefore, the driver's qui-
       esce()  implementation must not use locks or timeouts, or rely on them being called. The driver must discard all outstanding I/O instead of
       waiting for completion. At the conclusion of the quiesce() operation, the driver must guarantee that the device no  longer  has	access	to
       memory or interrupts.

       The  only  DDI  interfaces  that  can  be  called  by  the  quiesce() implementation are non-blocking functions, such as the ddi_get*() and
       ddi_put*() functions.

       If quiesce() determines a particular instance of the device cannot be quiesced when requested because of some exceptional  condition,  qui-
       esce() returns DDI_FAILURE. This rarely happens.

       If  a  driver  has  previously  implemented  the  obsolete reset() interface, its functionality must be merged into quiesce(). The driver's
       reset() routine is no longer called if an implementation of quiesce() is present.

       ddi_quiesce_not_needed() always returns DDI_SUCCESS. A driver can set its devo_quiesce device function to ddi_quiesce_not_needed() to indi-
       cate that the device it manages does not need to be quiesced.

RETURN VALUES

       quiesce() returns the following:

       DDI_SUCCESS    The device has been successfully quiesced.

       DDI_FAILURE    The operation failed.

CONTEXT

       This function is called from kernel context only.

SEE ALSO

       reboot(1M),   uadmin(1M),   uadmin(2),  attach(9E),  detach(9E),  ddi_add_intr(9F),  ddi_map_regs(9F),  pci_config_setup(9F),  timeout(9F),
       dev_ops(9S)

NOTES

       When quiesce() is called, the system is single-threaded, therefore the driver's quiesce() implementation must not be blocked. For  example,
       the implementation must not create or tear down mappings, call FMA functions, or create or cancel callbacks.

SunOS 5.11							    16 Sep 2008 						       quiesce(9E)