include/asm-mn10300/scatterlist.h

   1 /* MN10300 Scatterlist definitions
   2  *
   3  * Copyright (C) 2007 Matsushita Electric Industrial Co., Ltd.
   4  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11 #ifndef _ASM_SCATTERLIST_H
  12 #define _ASM_SCATTERLIST_H
  13
  14 #include <asm/types.h>
  15
  16 /*
  17  * Drivers must set either ->address or (preferred) page and ->offset
  18  * to indicate where data must be transferred to/from.
  19  *
  20  * Using page is recommended since it handles highmem data as well as
  21  * low mem. ->address is restricted to data which has a virtual mapping, and
  22  * it will go away in the future. Updating to page can be automated very
  23  * easily -- something like
  24  *
  25  * sg->address = some_ptr;
  26  *
  27  * can be rewritten as
  28  *
  29  * sg_set_page(virt_to_page(some_ptr));
  30  * sg->offset = (unsigned long) some_ptr & ~PAGE_MASK;
  31  *
  32  * and that's it. There's no excuse for not highmem enabling YOUR driver. /jens
  33  */
  34 struct scatterlist {
  35 #ifdef CONFIG_DEBUG_SG
  36         unsigned long   sg_magic;
  37 #endif
  38         unsigned long   page_link;
  39         unsigned int    offset;         /* for highmem, page offset */
  40         dma_addr_t      dma_address;
  41         unsigned int    length;
  42 };
  43
  44 #define ISA_DMA_THRESHOLD (0x00ffffff)
  45
  46 #endif /* _ASM_SCATTERLIST_H */