Kernel Functions for Drivers                 ddigetdevstate(9F)



NAME
     ddigetdevstate - Check device state

SYNOPSIS
     #include 
     #include 

     ddidevstatet ddigetdevstate(devinfot *dip);


INTERFACE LEVEL
     Solaris DI specific (Solaris DI)

PARAMETERS
     dip     Pointer to the device's devinfo structure


DESCRIPTION
     The ddigetdevstate() 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
     DIDEVSTATEOFLINE     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.


     DIDEVSTATEDOWN         The device is online but  unusable
                              due to a fault.


     DIDEVSTATEQUIESCED     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.


     DIDEVSTATEDEGRADED     The device is online but only able
                              to  provide  a  partial or degraded
                              service, due to a fault.


     DIDEVSTATEUP           The device  is  online  and  fully
                              operational.





SunOS 5.11         Last change: 13 August 1999                  1






Kernel Functions for Drivers                 ddigetdevstate(9F)



CONTEXT
     The ddigetdevstate() 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, indi-
     cating 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  exam-
     ple,  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), ddidevreportfault(9F)
























SunOS 5.11         Last change: 13 August 1999                  2