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_MAX,
  16 };
  17
  18 #define __DMA_ATTRS_LONGS BITS_TO_LONGS(DMA_ATTR_MAX)
  19
  20 /**
  21  * struct dma_attrs - an opaque container for DMA attributes
  22  * @flags - bitmask representing a collection of enum dma_attr
  23  */
  24 struct dma_attrs {
  25         unsigned long flags[__DMA_ATTRS_LONGS];
  26 };
  27
  28 #define DEFINE_DMA_ATTRS(x)                                     \
  29         struct dma_attrs x = {                                  \
  30                 .flags = { [0 ... __DMA_ATTRS_LONGS-1] = 0 },   \
  31         }
  32
  33 static inline void init_dma_attrs(struct dma_attrs *attrs)
  34 {
  35         bitmap_zero(attrs->flags, __DMA_ATTRS_LONGS);
  36 }
  37
  38 #ifdef CONFIG_HAVE_DMA_ATTRS
  39 /**
  40  * dma_set_attr - set a specific attribute
  41  * @attr: attribute to set
  42  * @attrs: struct dma_attrs (may be NULL)
  43  */
  44 static inline void dma_set_attr(enum dma_attr attr, struct dma_attrs *attrs)
  45 {
  46         if (attrs == NULL)
  47                 return;
  48         BUG_ON(attr >= DMA_ATTR_MAX);
  49         __set_bit(attr, attrs->flags);
  50 }
  51
  52 /**
  53  * dma_get_attr - check for a specific attribute
  54  * @attr: attribute to set
  55  * @attrs: struct dma_attrs (may be NULL)
  56  */
  57 static inline int dma_get_attr(enum dma_attr attr, struct dma_attrs *attrs)
  58 {
  59         if (attrs == NULL)
  60                 return 0;
  61         BUG_ON(attr >= DMA_ATTR_MAX);
  62         return test_bit(attr, attrs->flags);
  63 }
  64 #else /* !CONFIG_HAVE_DMA_ATTRS */
  65 static inline void dma_set_attr(enum dma_attr attr, struct dma_attrs *attrs)
  66 {
  67 }
  68
  69 static inline int dma_get_attr(enum dma_attr attr, struct dma_attrs *attrs)
  70 {
  71         return 0;
  72 }
  73 #endif /* CONFIG_HAVE_DMA_ATTRS */
  74 #endif /* _DMA_ATTR_H */