arch/ppc-chrp/exec/cachepredma.c

   1 /*
   2     Copyright © 1995-2010, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: CachePreDMA() - 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 <aros/libcall.h>
  14
  15 #include "exec_intern.h"
  16
  17 /*****************************************************************************
  18
  19     NAME */
  20 #include <proto/exec.h>
  21 #include <proto/kernel.h>
  22
  23         AROS_LH3(APTR, CachePreDMA,
  24
  25 /*  SYNOPSIS */
  26         AROS_LHA(APTR,    address, A0),
  27         AROS_LHA(ULONG *, length,  A1),
  28         AROS_LHA(ULONG,   flags,  D0),
  29
  30 /*  LOCATION */
  31         struct ExecBase *, SysBase, 127, Exec)
  32
  33 /*  FUNCTION
  34         Do everything necessary to make CPU caches aware that a DMA
  35         will happen. Virtual memory systems will make it possible
  36         that your memory is not at one block and not at the address
  37         you thought. This function gives you all the information
  38         you need to split the DMA request up and to convert virtual
  39         to physical addresses.
  40
  41     INPUTS
  42         address - Virtual address of memory affected by the DMA
  43         *length - Number of bytes affected
  44         flags   - DMA_Continue    - This is a call to continue a
  45                                     request that was broken up.
  46                   DMA_ReadFromRAM - Indicate that the DMA goes from
  47                                     RAM to the device. Set this bit
  48                                     in both calls.
  49
  50     RESULT
  51         The physical address in memory.
  52         *length contains the number of contiguous bytes in physical
  53         memory.
  54
  55     NOTES
  56         DMA must follow a call to CachePreDMA() and must be followed
  57         by a call to CachePostDMA().
  58
  59     EXAMPLE
  60
  61     BUGS
  62
  63     SEE ALSO
  64         CachePostDMA()
  65
  66     INTERNALS
  67
  68 ******************************************************************************/
  69 {
  70     AROS_LIBFUNC_INIT
  71
  72     void *addr = KrnVirtualToPhysical(address);
  73
  74     /* At PreDMA stage only data caches need to be flushed */
  75     //if (flags & DMA_ReadFromRAM)
  76
  77     CacheClearE(address, *length, CACRF_ClearD);
  78
  79     return addr;
  80
  81     AROS_LIBFUNC_EXIT
  82 } /* CachePreDMA() */
  83