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scatterlist.h

#ifndef _ASM_SCATTERLIST_H
#define _ASM_SCATTERLIST_H

#include <asm/types.h>

/*
 * Drivers must set either ->address or (preferred) page and ->offset
 * to indicate where data must be transferred to/from.
 *
 * Using page is recommended since it handles highmem data as well as
 * low mem. ->address is restricted to data which has a virtual mapping, and
 * it will go away in the future. Updating to page can be automated very
 * easily -- something like
 *
 * sg->address = some_ptr;
 *
 * can be rewritten as
 *
 * sg_set_buf(sg, some_ptr, length);
 *
 * and that's it. There's no excuse for not highmem enabling YOUR driver. /jens
 */
struct scatterlist {
#ifdef CONFIG_DEBUG_SG
      unsigned long     sg_magic;
#endif
      unsigned long     page_link;
      unsigned int      offset;           /* for highmem, page offset */

      dma_addr_t  dma_address;
      unsigned int      length;
};

/*
 * These macros should be used after a pci_map_sg call has been done
 * to get bus addresses of each of the SG entries and their lengths.
 * You should only work with the number of sg entries pci_map_sg
 * returns, or alternatively stop on the first sg_dma_len(sg) which
 * is 0.
 */
#define sg_dma_address(sg)    ((sg)->dma_address)
#define sg_dma_len(sg)        ((sg)->length)

#define ISA_DMA_THRESHOLD (0xffffffffUL)

#endif /* !_ASM_SCATTERLIST_H */

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