d5724f172f
This patch adds DMA_ATTR_NO_KERNEL_MAPPING attribute which lets the platform to avoid creating a kernel virtual mapping for the allocated buffer. On some architectures creating such mapping is non-trivial task and consumes very limited resources (like kernel virtual address space or dma consistent address space). Buffers allocated with this attribute can be only passed to user space by calling dma_mmap_attrs(). Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
79 lines
1.8 KiB
C
79 lines
1.8 KiB
C
#ifndef _DMA_ATTR_H
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#define _DMA_ATTR_H
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#include <linux/bitmap.h>
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#include <linux/bitops.h>
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#include <linux/bug.h>
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/**
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* an enum dma_attr represents an attribute associated with a DMA
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* mapping. The semantics of each attribute should be defined in
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* Documentation/DMA-attributes.txt.
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*/
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enum dma_attr {
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DMA_ATTR_WRITE_BARRIER,
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DMA_ATTR_WEAK_ORDERING,
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DMA_ATTR_WRITE_COMBINE,
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DMA_ATTR_NON_CONSISTENT,
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DMA_ATTR_NO_KERNEL_MAPPING,
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DMA_ATTR_MAX,
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};
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#define __DMA_ATTRS_LONGS BITS_TO_LONGS(DMA_ATTR_MAX)
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/**
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* struct dma_attrs - an opaque container for DMA attributes
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* @flags - bitmask representing a collection of enum dma_attr
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*/
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struct dma_attrs {
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unsigned long flags[__DMA_ATTRS_LONGS];
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};
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#define DEFINE_DMA_ATTRS(x) \
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struct dma_attrs x = { \
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.flags = { [0 ... __DMA_ATTRS_LONGS-1] = 0 }, \
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}
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static inline void init_dma_attrs(struct dma_attrs *attrs)
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{
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bitmap_zero(attrs->flags, __DMA_ATTRS_LONGS);
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}
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#ifdef CONFIG_HAVE_DMA_ATTRS
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/**
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* dma_set_attr - set a specific attribute
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* @attr: attribute to set
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* @attrs: struct dma_attrs (may be NULL)
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*/
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static inline void dma_set_attr(enum dma_attr attr, struct dma_attrs *attrs)
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{
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if (attrs == NULL)
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return;
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BUG_ON(attr >= DMA_ATTR_MAX);
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__set_bit(attr, attrs->flags);
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}
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/**
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* dma_get_attr - check for a specific attribute
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* @attr: attribute to set
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* @attrs: struct dma_attrs (may be NULL)
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*/
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static inline int dma_get_attr(enum dma_attr attr, struct dma_attrs *attrs)
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{
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if (attrs == NULL)
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return 0;
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BUG_ON(attr >= DMA_ATTR_MAX);
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return test_bit(attr, attrs->flags);
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}
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#else /* !CONFIG_HAVE_DMA_ATTRS */
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static inline void dma_set_attr(enum dma_attr attr, struct dma_attrs *attrs)
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{
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}
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static inline int dma_get_attr(enum dma_attr attr, struct dma_attrs *attrs)
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{
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return 0;
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}
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#endif /* CONFIG_HAVE_DMA_ATTRS */
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#endif /* _DMA_ATTR_H */
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