ddi_devmap_segmap(9F)

NAME

     devmap_setup, ddi_devmap_segmap - set up a user  mapping  to
     device memory using the devmap framework

SYNOPSIS

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

     int devmap_setup(dev_t dev,  offset_t  off,  ddi_as_handle_t
     as,  caddr_t *addrp, size_tlen, uint_t prot, uint_t maxprot,
     uint_t flags, cred_t *cred);

     int ddi_devmap_segmap(dev_t dev, off_t off,  ddi_as_handle_t
     as,  caddr_t  *addrp, off_tlen, uint_t prot, uint_t maxprot,
     uint_t flags, cred_t *cred);

INTERFACE LEVEL

     Solaris DDI specific (Solaris DDI).

PARAMETERS

     dev   Device whose memory is to be mapped.

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

     as    An opaque data structure that  describes  the  address
           space into which the device memory should be mapped.

     addrp Pointer to the starting address in the  address  space
           into which the device memory should be mapped.

     len   Length (in bytes) of the memory to be mapped.

     prot  A bit field that specifies the protections. Some  pos-
           sible settings combinations are:

           PROT_READ
                 Read access is desired.

           PROT_WRITE
                 Write access is desired.

           PROT_EXEC
                 Execute access is desired.

           PROT_USER
                 User-level access is  desired  (the  mapping  is
                 being  done  as  a  result  of  a mmap(2) system
                 call).

           PROT_ALL
                 All access is desired.

     maxprot
           Maximum protection flag possible  for  attempted  map-
           ping; the PROT_WRITE bit may be masked out if the user
           opened the special file read-only.

     flags Flags indicating type of mapping. The following  flags
           can be specified:

           MAP_PRIVATE
                 Changes are private.

           MAP_SHARED
                 Changes should be shared.

           MAP_FIXED
                 The user specified an address in  *addrp  rather
                 than letting the system choose an address.

     cred  Pointer to the user credential structure.

DESCRIPTION

     devmap_setup() and ddi_devmap_segmap() allow device  drivers
     to  use the devmap framework to set up user mappings to dev-
     ice memory.  The devmap framework  provides  several  advan-
     tages over the default device mapping framework that is used
     by ddi_segmap(9F) or  ddi_segmap_setup(9F).  Device  drivers
     should use the devmap framework, if the driver wants to:

        o  use an optimal MMU pagesize to minimize address trans-
           lations,

        o  conserve kernel resources,

        o  receive callbacks to manage events on the mapping,

        o  export kernel memory to applications,

        o  set up device contexts for the  user  mapping  if  the
           device requires context switching,

        o  assign device access attributes to the  user  mapping,
           or

        o  change the maximum protection for the mapping.

     devmap_setup() must be called in the segmap(9E) entry  point
     to    establish    the    mapping   for   the   application.
     ddi_devmap_segmap() can be called in, or  be  used  as,  the
     segmap(9E)    entry    point.    The   differences   between
     devmap_setup() and ddi_devmap_segmap() are in the data  type
     used for off and len.
     When   setting   up   the   mapping,    devmap_setup()   and
     ddi_devmap_segmap() call the devmap(9E) entry point to vali-
     date the range to be mapped. The devmap(9E) entry point also
     translates  the  logical offset (as seen by the application)
     to the  corresponding  physical  offset  within  the  device
     address  space.  If  the  driver  does  not  provide its own
     devmap(9E) entry point,  EINVAL  will  be  returned  to  the
     mmap(2) system call.

RETURN VALUES

     0     Successful completion.

     Non-zero
           An error occurred.  The return value of devmap_setup()
           and ddi_devmap_segmap() should be used directly in the
           segmap(9E) entry point.

CONTEXT

     devmap_setup() and ddi_devmap_segmap() can  be  called  from
     user or kernel context only.

SEE ALSO

     mmap(2),     devmap(9E),     segmap(9E),     ddi_segmap(9F),
     ddi_segmap_setup(9F), cb_ops(9S)

     Writing Device Drivers