devmap_default_access(9F)

NAME

     devmap_default_access - default driver memory  access  func-
     tion

SYNOPSIS

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

     int devmap_default_access(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).

PARAMETERS

     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.

     rw    Type of access.

DESCRIPTION

     devmap_default_access() is a function providing  the  seman-
     tics     of     devmap_access(9E).    The    drivers    call
     devmap_default_access() to handle the mappings that  do  not
     support   context   switching.   The   drivers  should  call
     devmap_do_ctxmgt(9F) for the mappings that  support  context
     management.

     devmap_default_access()   can   either   be   called    from
     devmap_access(9E)  or be used as the devmap_access(9E) entry
     point. The arguments dhp,  pvtp,  off,  len,  type,  and  rw
     are  provided  by the devmap_access(9E) entry point and must
     not be modified.

RETURN VALUES

     0     Successful completion.

     Non-zero
           An error occurred.

CONTEXT

     devmap_default_access() must be  called  from  the  driver's
     devmap_access(9E) entry point.

EXAMPLES

     Example 1: Using devmap_default_access in devmap_access.

     The    following    shows    an     example     of     using
     devmap_default_access()   in   the  devmap_access(9E)  entry
     point.

     ...
     #define OFF_DO_CTXMGT  0x40000000
     #define OFF_NORMAL     0x40100000
     #define CTXMGT_SIZE    0x100000
     #define NORMAL_SIZE    0x100000

     /*
      * Driver devmap_contextmgt(9E) callback function.
      */
     static int
     xx_context_mgt(devmap_cookie_t dhp, void *pvtp, offset_t offset,
         size_t length, uint_t type, uint_t rw)
     {
         ......
         /*
          * see devmap_contextmgt(9E) for an example
          */
     }

     /*
      * Driver devmap_access(9E) entry point
      */
     static int
     xxdevmap_access(devmap_cookie_t dhp, void *pvtp, offset_t off,
         size_t len, uint_t type, uint_t rw)
     {
         offset_t diff;
         int err;

         /*
          * check if off is within the range that supports
          * context management.
          */
         if ((diff = off - OFF_DO_CTXMG) >= 0 && diff < CTXMGT_SIZE) {
             /*
              * calculates the length for context switching
              */
             if ((len + off) > (OFF_DO_CTXMGT + CTXMGT_SIZE))
                 return (-1);
             /*
              * perform context switching
              */

             err = devmap_do_ctxmgt(dhp, pvtp, off, len, type,
                 rw,  xx_context_mgt);
         /*
          * check if off is within the range that does normal
          * memory mapping.
          */
         } else if ((diff = off - OFF_NORMAL) >= 0 && diff < NORMAL_SIZE) {
             if ((len + off) > (OFF_NORMAL + NORMAL_SIZE))
                 return (-1);
             err = devmap_default_access(dhp, pvtp, off, len, type, rw);
         } else
             return (-1);

         return (err);
     }

SEE ALSO

     devmap_access(9E),                     devmap_do_ctxmgt(9F),
     devmap_callback_ctl(9S)

     Writing Device Drivers