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_MAX,
  17 };
  18
  19 #define __DMA_ATTRS_LONGS BITS_TO_LONGS(DMA_ATTR_MAX)
  20
  21 /**
  22  * struct dma_attrs - an opaque container for DMA attributes
  23  * @flags - bitmask representing a collection of enum dma_attr
  24  */
  25 struct dma_attrs {
  26         unsigned long flags[__DMA_ATTRS_LONGS];
  27 };
  28
  29 #define DEFINE_DMA_ATTRS(x)                                     \
  30         struct dma_attrs x = {                                  \
  31                 .flags = { [0 ... __DMA_ATTRS_LONGS-1] = 0 },   \
  32         }
  33
  34 static inline void init_dma_attrs(struct dma_attrs *attrs)
  35 {
  36         bitmap_zero(attrs->flags, __DMA_ATTRS_LONGS);
  37 }
  38
  39 #ifdef CONFIG_HAVE_DMA_ATTRS
  40 /**
  41  * dma_set_attr - set a specific attribute
  42  * @attr: attribute to set
  43  * @attrs: struct dma_attrs (may be NULL)
  44  */
  45 static inline void dma_set_attr(enum dma_attr attr, struct dma_attrs *attrs)
  46 {
  47         if (attrs == NULL)
  48                 return;
  49         BUG_ON(attr >= DMA_ATTR_MAX);
  50         __set_bit(attr, attrs->flags);
  51 }
  52
  53 /**
  54  * dma_get_attr - check for a specific attribute
  55  * @attr: attribute to set
  56  * @attrs: struct dma_attrs (may be NULL)
  57  */
  58 static inline int dma_get_attr(enum dma_attr attr, struct dma_attrs *attrs)
  59 {
  60         if (attrs == NULL)
  61                 return 0;
  62         BUG_ON(attr >= DMA_ATTR_MAX);
  63         return test_bit(attr, attrs->flags);
  64 }
  65 #else /* !CONFIG_HAVE_DMA_ATTRS */
  66 static inline void dma_set_attr(enum dma_attr attr, struct dma_attrs *attrs)
  67 {
  68 }
  69
  70 static inline int dma_get_attr(enum dma_attr attr, struct dma_attrs *attrs)
  71 {
  72         return 0;
  73 }
  74 #endif /* CONFIG_HAVE_DMA_ATTRS */
  75 #endif /* _DMA_ATTR_H */