linux/include/asm-generic/scatterlist.h

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#ifndef __ASM_GENERIC_SCATTERLIST_H
#define __ASM_GENERIC_SCATTERLIST_H
#include <linux/types.h>
struct scatterlist {
#ifdef CONFIG_DEBUG_SG
unsigned long sg_magic;
#endif
unsigned long page_link;
unsigned int offset;
unsigned int length;
dma_addr_t dma_address;
unsigned int dma_length;
};
/*
* These macros should be used after a dma_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)
#ifndef sg_dma_len
/*
* Normally, you have an iommu on 64 bit machines, but not on 32 bit
* machines. Architectures that are differnt should override this.
*/
#if __BITS_PER_LONG == 64
#define sg_dma_len(sg) ((sg)->dma_length)
#else
#define sg_dma_len(sg) ((sg)->length)
#endif /* 64 bit */
#endif /* sg_dma_len */
#ifndef ISA_DMA_THRESHOLD
#define ISA_DMA_THRESHOLD (~0UL)
#endif
#define ARCH_HAS_SG_CHAIN
#endif /* __ASM_GENERIC_SCATTERLIST_H */