arch/xtensa/include/asm/dma.h

   1 /*
   2  * include/asm-xtensa/dma.h
   3  *
   4  * This file is subject to the terms and conditions of the GNU General Public
   5  * License.  See the file "COPYING" in the main directory of this archive
   6  * for more details.
   7  *
   8  * Copyright (C) 2003 - 2005 Tensilica Inc.
   9  */
  10
  11 #ifndef _XTENSA_DMA_H
  12 #define _XTENSA_DMA_H
  13
  14 #include <asm/io.h>             /* need byte IO */
  15
  16 /*
  17  * This is only to be defined if we have PC-like DMA.
  18  * By default this is not true on an Xtensa processor,
  19  * however on boards with a PCI bus, such functionality
  20  * might be emulated externally.
  21  *
  22  * NOTE:  there still exists driver code that assumes
  23  * this is defined, eg. drivers/sound/soundcard.c (as of 2.4).
  24  */
  25 #define MAX_DMA_CHANNELS        8
  26
  27 /*
  28  * The maximum virtual address to which DMA transfers
  29  * can be performed on this platform.
  30  *
  31  * NOTE: This is board (platform) specific, not processor-specific!
  32  *
  33  * NOTE: This assumes DMA transfers can only be performed on
  34  *      the section of physical memory contiguously mapped in virtual
  35  *      space for the kernel.  For the Xtensa architecture, this
  36  *      means the maximum possible size of this DMA area is
  37  *      the size of the statically mapped kernel segment
  38  *      (XCHAL_KSEG_{CACHED,BYPASS}_SIZE), ie. 128 MB.
  39  *
  40  * NOTE: When the entire KSEG area is DMA capable, we subtract
  41  *      one from the max address so that the virt_to_phys() macro
  42  *      works correctly on the address (otherwise the address
  43  *      enters another area, and virt_to_phys() may not return
  44  *      the value desired).
  45  */
  46
  47 #ifndef MAX_DMA_ADDRESS
  48 #define MAX_DMA_ADDRESS         (PAGE_OFFSET + XCHAL_KIO_SIZE - 1)
  49 #endif
  50
  51 /* Reserve and release a DMA channel */
  52 extern int request_dma(unsigned int dmanr, const char * device_id);
  53 extern void free_dma(unsigned int dmanr);
  54
  55 #ifdef CONFIG_PCI
  56 extern int isa_dma_bridge_buggy;
  57 #else
  58 #define isa_dma_bridge_buggy    (0)
  59 #endif
  60
  61
  62 #endif