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device_probing(3K)             DG/UX R4.11MU05            device_probing(3K)


NAME
       deviceprobing: iodofirstshortboardaccess,
       iodofirstlongboardaccess, ioperformreset - probe for and reset
       devices

SYNOPSIS
       #include "/usr/src/uts/aviion/ii/iuc.h"
       #include "/usr/src/uts/aviion/ii/iio.h"

       statustype   iodofirstshortboardaccess (
           bit16eptrtype     registerptr,             /*READWRITE*/
           bit16eptrtype     registercontentsptr,    /*READWRITE*/
           booleantype        writetoregister         /*READONLY*/
                                                    )

       statustype   iodofirstlongboardaccess (
           bit32eptrtype     registerptr,             /*READWRITE*/
           bit32eptrtype     registercontentsptr,    /*READWRITE*/
           booleantype        writetoregister         /*READONLY*/
                                                   )

       void          ioperformreset (
           ucresetenumtype      resettype            /*READONLY*/
                                      )

   where:
       registercontentsptr
                          A pointer to a 16- or 32-bit read/write buffer.
                          For a write operation, the routine writes the con­
                          tents of this buffer to the register.  For a read
                          operation, the routine stores in this buffer the
                          data read from the register.
       registerptr       Pointer to register on the board to be accessed.
       writetoregister  A boolean value indicating whether a routine is
                          reading from or writing to a register.  TRUE indi­
                          cates write; FALSE indicates read.
       resetvariety      An enumeration specifying which type of reset is
                          to be done.

DESCRIPTION
       The following routines are described in this man page:
       iodofirstshortboardaccess
              Check 16-bit-register board's presence
       iodofirstlongboardaccess
              Check 32-bit-register board's presence
       ioperformreset
              Perform specified type of reset

       A device driver's driverconfigure routine is responsible for verify­
       ing that the named device is attached and working.  Often, the only
       way to verify a device is to read various memory-mapped device con­
       trol registers that will contain known values if the device in ques­
       tion is present, but will generate a memory fault otherwise.  Since
       such a fault will cause a system panic or hang, it is important to
       use the kernel-supplied routines for the first such register access.
       These two routines are iodofirstlongboardaccess (for 32-bit reg­
       isters) and iodofirstshortboardaccess (for 16-bit registers).
       Both return the error IOENXIODEVICEDOESNOTEXIST if the register
       (and thus, the device) does not exist.  Note that if you must map the
       device registers (as described in memoryallocation(3K)), the mapping
       must be in effect before trying to access the device.

       Some types of integrated devices also need to be reinitialized to a
       known state before making them available to the rest of the system.
       The ioperformreset routine performs the specified type of device
       reset.  It uses the clock and await mechanisms, so it should not be
       used in an environment where they are unavailable (for example, dur­
       ing shutdown).  Reset is only supported for certain types of inte­
       grated devices; see the enumerated type ucresetenumtype in
       /usr/src/uts/aviion/ii/iuc.h for details.

DIAGNOSTICS
   Return Value
       For iodofirstlongboardaccess:
              OK     The register was accessed successfully.
              IOENXIODEVICEDOESNOTEXIST
                     The board is not accessible.

       For iodofirstshortboardaccess:
              OK     The register was accessed successfully.
              IOENXIODEVICEDOESNOTEXIST
                     The board is not accessible.

       For ioperformreset:
              None.

   Errors
       None.

   Abort Conditions
       For ioperformreset, panic may be invoked with the following error
       codes:
              IOPANICBADRESETTYPE
                     The parameter passed is not recognizable.

       For the other routines: none.

SEE ALSO
       deviceconfiguration(3K), memoryallocation(3K).
       Programming in the DG/UX Kernel Environment.


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