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_MAX,
  19 };
  20
  21 #define __DMA_ATTRS_LONGS BITS_TO_LONGS(DMA_ATTR_MAX)
  22
  23 /**
  24  * struct dma_attrs - an opaque container for DMA attributes
  25  * @flags - bitmask representing a collection of enum dma_attr
  26  */
  27 struct dma_attrs {
  28         unsigned long flags[__DMA_ATTRS_LONGS];
  29 };
  30
  31 #define DEFINE_DMA_ATTRS(x)                                     \
  32         struct dma_attrs x = {                                  \
  33                 .flags = { [0 ... __DMA_ATTRS_LONGS-1] = 0 },   \
  34         }
  35
  36 static inline void init_dma_attrs(struct dma_attrs *attrs)
  37 {
  38         bitmap_zero(attrs->flags, __DMA_ATTRS_LONGS);
  39 }
  40
  41 #ifdef CONFIG_HAVE_DMA_ATTRS
  42 /**
  43  * dma_set_attr - set a specific attribute
  44  * @attr: attribute to set
  45  * @attrs: struct dma_attrs (may be NULL)
  46  */
  47 static inline void dma_set_attr(enum dma_attr attr, struct dma_attrs *attrs)
  48 {
  49         if (attrs == NULL)
  50                 return;
  51         BUG_ON(attr >= DMA_ATTR_MAX);
  52         __set_bit(attr, attrs->flags);
  53 }
  54
  55 /**
  56  * dma_get_attr - check for a specific attribute
  57  * @attr: attribute to set
  58  * @attrs: struct dma_attrs (may be NULL)
  59  */
  60 static inline int dma_get_attr(enum dma_attr attr, struct dma_attrs *attrs)
  61 {
  62         if (attrs == NULL)
  63                 return 0;
  64         BUG_ON(attr >= DMA_ATTR_MAX);
  65         return test_bit(attr, attrs->flags);
  66 }
  67 #else /* !CONFIG_HAVE_DMA_ATTRS */
  68 static inline void dma_set_attr(enum dma_attr attr, struct dma_attrs *attrs)
  69 {
  70 }
  71
  72 static inline int dma_get_attr(enum dma_attr attr, struct dma_attrs *attrs)
  73 {
  74         return 0;
  75 }
  76 #endif /* CONFIG_HAVE_DMA_ATTRS */
  77 #endif /* _DMA_ATTR_H */