rom/exec/cachepostdma.c

   1 /*
   2     Copyright © 1995-2010, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: CachePostDMA() - Do what is necessary for DMA.
   6     Lang: english
   7 */
   8
   9 #define DEBUG 0
  10
  11 #include <aros/debug.h>
  12 #include <exec/types.h>
  13 #include <exec/execbase.h>
  14 #include <aros/libcall.h>
  15
  16 /*****************************************************************************
  17
  18     NAME */
  19 #include <proto/exec.h>
  20
  21         AROS_LH3(void, CachePostDMA,
  22
  23 /*  SYNOPSIS */
  24         AROS_LHA(APTR,    address, A0),
  25         AROS_LHA(ULONG *, length,  A1),
  26         AROS_LHA(ULONG,   flags,  D0),
  27
  28 /*  LOCATION */
  29         struct ExecBase *, SysBase, 128, Exec)
  30
  31 /*  FUNCTION
  32         Do everything necessary to make CPU caches aware that a DMA has
  33         happened.
  34
  35     INPUTS
  36         address - Virtual address of memory affected by the DMA
  37         *length - Number of bytes affected
  38         flags   - DMA_NoModify    - Indicate that the memory did not change.
  39                   DMA_ReadFromRAM - Indicate that the DMA goes from RAM
  40                                     to the device. Set this bit in
  41                                     both calls.
  42
  43     RESULT
  44
  45     NOTES
  46         DMA must follow a call to CachePreDMA() and must be followed
  47         by a call to CachePostDMA().
  48
  49     EXAMPLE
  50
  51     BUGS
  52
  53     SEE ALSO
  54         CachePreDMA()
  55
  56     INTERNALS
  57
  58 ******************************************************************************/
  59 {
  60     AROS_LIBFUNC_INIT
  61
  62     /*
  63      * Due to the strong cache coherency of x86 systems this function
  64      * is actually not needed. CPU snoops the address lines and
  65      * invalidate all cache which is out-of-date. It is valid for both
  66      * D and I caches). Even a BM-DMA transfer are perfectly safe here.
  67      */
  68
  69     AROS_LIBFUNC_EXIT
  70 } /* CachePostDMA */
  71