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_MAX,
  21 };
  22
  23 #define __DMA_ATTRS_LONGS BITS_TO_LONGS(DMA_ATTR_MAX)
  24
  25 /**
  26  * struct dma_attrs - an opaque container for DMA attributes
  27  * @flags - bitmask representing a collection of enum dma_attr
  28  */
  29 struct dma_attrs {
  30         unsigned long flags[__DMA_ATTRS_LONGS];
  31 };
  32
  33 #define DEFINE_DMA_ATTRS(x)                                     \
  34         struct dma_attrs x = {                                  \
  35                 .flags = { [0 ... __DMA_ATTRS_LONGS-1] = 0 },   \
  36         }
  37
  38 static inline void init_dma_attrs(struct dma_attrs *attrs)
  39 {
  40         bitmap_zero(attrs->flags, __DMA_ATTRS_LONGS);
  41 }
  42
  43 #ifdef CONFIG_HAVE_DMA_ATTRS
  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 #else /* !CONFIG_HAVE_DMA_ATTRS */
  70 static inline void dma_set_attr(enum dma_attr attr, struct dma_attrs *attrs)
  71 {
  72 }
  73
  74 static inline int dma_get_attr(enum dma_attr attr, struct dma_attrs *attrs)
  75 {
  76         return 0;
  77 }
  78 #endif /* CONFIG_HAVE_DMA_ATTRS */
  79 #endif /* _DMA_ATTR_H */