Manual Pages for UNIX Operating System command usage for man devmap_contextmgt

Driver Entry Points                         devmap_contextmgt(9E)



NAME
     devmap_contextmgt - driver  callback  function  for  context
     management

SYNOPSIS
     #include 
     #include 



     int devmap_contextmgt(devmap_cookie_t dhp, void *pvtp,
          offset_t off, size_t len, uint_t type, uint_t rw);


INTERFACE LEVEL
     Solaris DDI specific (Solaris DDI).

ARGUMENTS
     dhp      An opaque mapping handle that the  system  uses  to
              describe the mapping.


     pvtp     Driver private mapping data.


     off      User offset within the  logical  device  memory  at
              which the access begins.


     len      Length (in bytes) of the memory being accessed.


     type     Type of access operation. Possible values are:

              DEVMAP_ACCESS     Memory access.


              DEVMAP_LOCK       Lock the memory being accessed.


              DEVMAP_UNLOCK     Unlock the memory being accessed.



     rw       Direction of access. Possible values are:

              DEVMAP_READ      Read access attempted.


              DEVMAP_WRITE     Write access attempted.





SunOS 5.11          Last change: 16 Jan 1997                    1






Driver Entry Points                         devmap_contextmgt(9E)



DESCRIPTION
     devmap_contextmgt() is a driver-supplied function that  per-
     forms  device  context  switching  on  a   mapping.   Device
     drivers  pass  devmap_contextmgt()   as   an   argument   to
     devmap_do_ctxmgt(9F)  in the  devmap_access(9E) entry point.
     The system will  call  devmap_contextmgt()  when  memory  is
     accessed.  The  system  expects  devmap_contextmgt() to load
     the memory address translations of the  mapping  by  calling
     devmap_load(9F) before returning.


     dhp uniquely identifies the mapping and is used as an  argu-
     ment  to   devmap_load(9F)  to validate the mapping. off and
     len define the range to be affected  by  the  operations  in
     devmap_contextmgt().


     The driver must check if there is already  a  mapping  esta-
     blished  at  off  that  needs  to  be unloaded. If a mapping
     exists    at    off,    devmap_contextmgt()    must     call
     devmap_unload(9F)  on the current mapping. devmap_unload(9F)
     must be followed by devmap_load() on the mapping  that  gen-
     erated  this  call to devmap_contextmgt(). devmap_unload(9F)
     unloads  the   current   mapping   so   that   a   call   to
     devmap_access(9E),   which   causes   the   system  to  call
     devmap_contextmgt(), will be generated  the  next  time  the
     mapping is accessed.


     pvtp is a pointer to the driver's private mapping data  that
     was  allocated  and  initialized in the devmap_map(9E) entry
     point. type  defines  the  type  of  operation  that  device
     drivers  should  perform  on  the memory object.  If type is
     either DEVMAP_LOCK or DEVMAP_UNLOCK, the  length  passed  to
     either  devmap_unload(9F) or devmap_load(9F) must be same as
     len. rw specifies the access direction on the memory object.


     A non-zero return value from   devmap_contextmgt()  will  be
     returned   to    devmap_access(9E)   and   will   cause  the
     corresponding operation to fail. The failure may result in a
     SIGSEGV or SIGBUS signal being delivered to the process.

RETURN VALUES
     0           Successful completion.


     Non-zero    An error occurred.


EXAMPLES




SunOS 5.11          Last change: 16 Jan 1997                    2






Driver Entry Points                         devmap_contextmgt(9E)



     Example 1 managing a device context


     The following shows an example of managing a device context.


       struct xxcontext cur_ctx;
       static int
       xxdevmap_contextmgt(devmap_cookie_t dhp, void *pvtp, offset_t off,
            size_t len, uint_t type, uint_t rw)
       {
           devmap_cookie_t cur_dhp;
           struct xxpvtdata *p;
           struct xxpvtdata *pvp = (struct xxpvtdata *)pvtp;
           struct xx_softc  *softc = pvp->softc;
           int    err;

           mutex_enter(&softc->mutex);

           /*
            * invalidate the translations of current context before
            * switching context.
            */
           if (cur_ctx != NULL && cur_ctx != pvp->ctx) {
               p = cur_ctx->pvt;
               cur_dhp = p->dhp;
               if ((err = devmap_unload(cur_dhp, off, len)) != 0)
                   return (err);
           }
           /* Switch device context - device dependent*/
           ...
           /* Make handle the new current mapping */
           cur_ctx = pvp->ctx;

           /*
            * Load the address translations of the calling context.
            */
           err = devmap_load(pvp->dhp, off, len, type, rw);

           mutex_exit(&softc->mutex);

           return (err);
       }


SEE ALSO
     devmap_access(9E),   devmap_do_ctxmgt(9F)   devmap_load(9F),
     devmap_unload(9F)


     Writing Device Drivers




SunOS 5.11          Last change: 16 Jan 1997                    3