root/include/linux/dma-attrs.h

DEFINITIONS

1. init_dma_attrs
2. dma_set_attr
3. dma_get_attr
4. dma_set_attr
5. dma_get_attr

#ifndef _DMA_ATTR_H
#define _DMA_ATTR_H

#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/bug.h>

/**
 * an enum dma_attr represents an attribute associated with a DMA
 * mapping. The semantics of each attribute should be defined in
 * Documentation/DMA-attributes.txt.
 */
enum dma_attr {
        DMA_ATTR_WRITE_BARRIER,
        DMA_ATTR_WEAK_ORDERING,
        DMA_ATTR_MAX,
};

#define __DMA_ATTRS_LONGS BITS_TO_LONGS(DMA_ATTR_MAX)

/**
 * struct dma_attrs - an opaque container for DMA attributes
 * @flags - bitmask representing a collection of enum dma_attr
 */
struct dma_attrs {
        unsigned long flags[__DMA_ATTRS_LONGS];
};

#define DEFINE_DMA_ATTRS(x)                                     \
        struct dma_attrs x = {                                  \
                .flags = { [0 ... __DMA_ATTRS_LONGS-1] = 0 },   \
        }

static inline void init_dma_attrs(struct dma_attrs *attrs)
{
        bitmap_zero(attrs->flags, __DMA_ATTRS_LONGS);
}

#ifdef CONFIG_HAVE_DMA_ATTRS
/**
 * dma_set_attr - set a specific attribute
 * @attr: attribute to set
 * @attrs: struct dma_attrs (may be NULL)
 */
static inline void dma_set_attr(enum dma_attr attr, struct dma_attrs *attrs)
{
        if (attrs == NULL)
                return;
        BUG_ON(attr >= DMA_ATTR_MAX);
        __set_bit(attr, attrs->flags);
}

/**
 * dma_get_attr - check for a specific attribute
 * @attr: attribute to set
 * @attrs: struct dma_attrs (may be NULL)
 */
static inline int dma_get_attr(enum dma_attr attr, struct dma_attrs *attrs)
{
        if (attrs == NULL)
                return 0;
        BUG_ON(attr >= DMA_ATTR_MAX);
        return test_bit(attr, attrs->flags);
}
#else /* !CONFIG_HAVE_DMA_ATTRS */
static inline void dma_set_attr(enum dma_attr attr, struct dma_attrs *attrs)
{
}

static inline int dma_get_attr(enum dma_attr attr, struct dma_attrs *attrs)
{
        return 0;
}
#endif /* CONFIG_HAVE_DMA_ATTRS */
#endif /* _DMA_ATTR_H */