arch/.unmaintained/dummy/cachepredma.c

   1 |*****************************************************************************
   2 |
   3 |   NAME
   4 |
   5 |       __AROS_LH3(APTR, CachePreDMA,
   6 |
   7 |   SYNOPSIS
   8 |       __AROS_LA(APTR,    address, A0),
   9 |       __AROS_LA(ULONG *, length,  A1),
  10 |       __AROS_LA(ULONG,   flags,  D0),
  11 |
  12 |   LOCATION
  13 |       struct ExecBase *, SysBase, 127, Exec)
  14 |
  15 |   FUNCTION
  16 |       Do everything necessary to make CPU caches aware that a DMA will happen.
  17 |       Virtual memory systems will make it possible that your memory isn't at
  18 |       one block and not at the address you thought. This function gives you
  19 |       all the information you need to split the DMA request up and to convert
  20 |       virtual to physical addresses.
  21 |
  22 |   INPUTS
  23 |       address - Virtual address of memory affected by the DMA
  24 |       *length - Number of bytes affected
  25 |       flags   - DMA_Continue    - This is a call to continue a request that
  26 |                                   was broken up.
  27 |                 DMA_ReadFromRAM - Indicate that the DMA goes from RAM
  28 |                                   to the device. Set this bit in bot calls.
  29 |
  30 |   RESULT
  31 |       The physical address in memory.
  32 |       *length contains the number of contiguous bytes in physical memory.
  33 |
  34 |   NOTES
  35 |       DMA must follow a call to CachePreDMA() and must be followed
  36 |       by a call to CachePostDMA().
  37 |
  38 |   EXAMPLE
  39 |
  40 |   BUGS
  41 |
  42 |   SEE ALSO
  43 |       CachePostDMA()
  44 |
  45 |   INTERNALS
  46 |
  47 |   HISTORY
  48 |
  49 |******************************************************************************
  50
  51         | Simple 68000s have no chaches
  52         .globl  _Exec_CachePreDMA
  53 _Exec_CachePreDMA:
  54         rts
  55