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  1. #ifndef _DMA_ATTR_H
  2. #define _DMA_ATTR_H
  3.  
  4. #include <linux/bitmap.h>
  5. #include <linux/bitops.h>
  6. #include <linux/bug.h>
  7.  
  8. /**
  9.  * an enum dma_attr represents an attribute associated with a DMA
  10.  * mapping. The semantics of each attribute should be defined in
  11.  * Documentation/DMA-attributes.txt.
  12.  */
  13. enum dma_attr {
  14.         DMA_ATTR_WRITE_BARRIER,
  15.         DMA_ATTR_WEAK_ORDERING,
  16.         DMA_ATTR_WRITE_COMBINE,
  17.         DMA_ATTR_NON_CONSISTENT,
  18.         DMA_ATTR_NO_KERNEL_MAPPING,
  19.         DMA_ATTR_SKIP_CPU_SYNC,
  20.         DMA_ATTR_FORCE_CONTIGUOUS,
  21.         DMA_ATTR_MAX,
  22. };
  23.  
  24. #define __DMA_ATTRS_LONGS BITS_TO_LONGS(DMA_ATTR_MAX)
  25.  
  26. /**
  27.  * struct dma_attrs - an opaque container for DMA attributes
  28.  * @flags - bitmask representing a collection of enum dma_attr
  29.  */
  30. struct dma_attrs {
  31.         unsigned long flags[__DMA_ATTRS_LONGS];
  32. };
  33.  
  34. #define DEFINE_DMA_ATTRS(x)                                     \
  35.         struct dma_attrs x = {                                  \
  36.                 .flags = { [0 ... __DMA_ATTRS_LONGS-1] = 0 },   \
  37.         }
  38.  
  39. static inline void init_dma_attrs(struct dma_attrs *attrs)
  40. {
  41.         bitmap_zero(attrs->flags, __DMA_ATTRS_LONGS);
  42. }
  43.  
  44. /**
  45.  * dma_set_attr - set a specific attribute
  46.  * @attr: attribute to set
  47.  * @attrs: struct dma_attrs (may be NULL)
  48.  */
  49. static inline void dma_set_attr(enum dma_attr attr, struct dma_attrs *attrs)
  50. {
  51.         if (attrs == NULL)
  52.                 return;
  53.         BUG_ON(attr >= DMA_ATTR_MAX);
  54.         __set_bit(attr, attrs->flags);
  55. }
  56.  
  57. /**
  58.  * dma_get_attr - check for a specific attribute
  59.  * @attr: attribute to set
  60.  * @attrs: struct dma_attrs (may be NULL)
  61.  */
  62. static inline int dma_get_attr(enum dma_attr attr, struct dma_attrs *attrs)
  63. {
  64.         if (attrs == NULL)
  65.                 return 0;
  66.         BUG_ON(attr >= DMA_ATTR_MAX);
  67.         return test_bit(attr, attrs->flags);
  68. }
  69.  
  70. #endif /* _DMA_ATTR_H */
  71.