arch/m68k-all/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 extern void AROS_SLIB_ENTRY(CachePreDMA_00,Exec,127)(void);
  16 extern void AROS_SLIB_ENTRY(CachePreDMA_40,Exec,127)(void);
  17 /*****************************************************************************
  18
  19     NAME */
  20 #include <proto/exec.h>
  21
  22         AROS_LH3(APTR, CachePreDMA,
  23
  24 /*  SYNOPSIS */
  25         AROS_LHA(APTR,    address, A0),
  26         AROS_LHA(ULONG *, length,  A1),
  27         AROS_LHA(ULONG,   flags,  D0),
  28
  29 /*  LOCATION */
  30         struct ExecBase *, SysBase, 127, Exec)
  31
  32 /*  FUNCTION
  33         Do everything necessary to make CPU caches aware that a DMA
  34         will happen. Virtual memory systems will make it possible
  35         that your memory is not at one block and not at the address
  36         you thought. This function gives you all the information
  37         you need to split the DMA request up and to convert virtual
  38         to physical addresses.
  39
  40     INPUTS
  41         address - Virtual address of memory affected by the DMA
  42         *length - Number of bytes affected
  43         flags   - DMA_Continue    - This is a call to continue a
  44                                     request that was broken up.
  45                   DMA_ReadFromRAM - Indicate that the DMA goes from
  46                                     RAM to the device. Set this bit
  47                                     in both calls.
  48
  49     RESULT
  50         The physical address in memory.
  51         *length contains the number of contiguous bytes in physical
  52         memory.
  53
  54     NOTES
  55         DMA must follow a call to CachePreDMA() and must be followed
  56         by a call to CachePostDMA().
  57
  58     EXAMPLE
  59
  60     BUGS
  61
  62     SEE ALSO
  63         CachePostDMA()
  64
  65     INTERNALS
  66         This function should be replaced by a function in $(KERNEL).
  67
  68 ******************************************************************************/
  69 {
  70     AROS_LIBFUNC_INIT
  71     void (*func)(void);
  72
  73     /* When called the first time, this patches up the
  74      * Exec syscall table to directly point to the right routine.
  75      */
  76     Disable();
  77     if (SysBase->AttnFlags & AFF_68040) {
  78         /* 68040 support */
  79         func = AROS_SLIB_ENTRY(CachePreDMA_40, Exec, 127);
  80     } else {
  81         /* Everybody else (68000, 68010) */
  82         func = AROS_SLIB_ENTRY(CachePreDMA_00, Exec, 127);
  83     }
  84
  85     SetFunction((struct Library *)SysBase, -LIB_VECTSIZE * 127, func);
  86     Enable();
  87
  88     /* Call 'myself', which is now pointing to the correct routine */
  89     return CachePreDMA(address, length, flags);
  90
  91     AROS_LIBFUNC_EXIT
  92 } /* CachePreDMA() */