dma-attrs.h

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#ifndef _DMA_ATTR_H
#define _DMA_ATTR_H

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

enum dma_attr {
    DMA_ATTR_WRITE_BARRIER,
    DMA_ATTR_WEAK_ORDERING,
    DMA_ATTR_WRITE_COMBINE,
    DMA_ATTR_NON_CONSISTENT,
    DMA_ATTR_NO_KERNEL_MAPPING,
    DMA_ATTR_SKIP_CPU_SYNC,
    DMA_ATTR_MAX,
};

#define __DMA_ATTRS_LONGS BITS_TO_LONGS(DMA_ATTR_MAX)

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

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);
}

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 */