include/linux/dma-attrs.h

   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_ALLOC_SINGLE_PAGES,
  22         DMA_ATTR_MAX,
  23 };
  24
  25 #define __DMA_ATTRS_LONGS BITS_TO_LONGS(DMA_ATTR_MAX)
  26
  27 /**
  28  * struct dma_attrs - an opaque container for DMA attributes
  29  * @flags - bitmask representing a collection of enum dma_attr
  30  */
  31 struct dma_attrs {
  32         unsigned long flags[__DMA_ATTRS_LONGS];
  33 };
  34
  35 #define DEFINE_DMA_ATTRS(x)                                     \
  36         struct dma_attrs x = {                                  \
  37                 .flags = { [0 ... __DMA_ATTRS_LONGS-1] = 0 },   \
  38         }
  39
  40 static inline void init_dma_attrs(struct dma_attrs *attrs)
  41 {
  42         bitmap_zero(attrs->flags, __DMA_ATTRS_LONGS);
  43 }
  44
  45 /**
  46  * dma_set_attr - set a specific attribute
  47  * @attr: attribute to set
  48  * @attrs: struct dma_attrs (may be NULL)
  49  */
  50 static inline void dma_set_attr(enum dma_attr attr, struct dma_attrs *attrs)
  51 {
  52         if (attrs == NULL)
  53                 return;
  54         BUG_ON(attr >= DMA_ATTR_MAX);
  55         __set_bit(attr, attrs->flags);
  56 }
  57
  58 /**
  59  * dma_get_attr - check for a specific attribute
  60  * @attr: attribute to set
  61  * @attrs: struct dma_attrs (may be NULL)
  62  */
  63 static inline int dma_get_attr(enum dma_attr attr, struct dma_attrs *attrs)
  64 {
  65         if (attrs == NULL)
  66                 return 0;
  67         BUG_ON(attr >= DMA_ATTR_MAX);
  68         return test_bit(attr, attrs->flags);
  69 }
  70
  71 #endif /* _DMA_ATTR_H */