4b9347dcbe
This patch adds DMA_ATTR_FORCE_CONTIGUOUS attribute to the DMA-mapping subsystem. By default DMA-mapping subsystem is allowed to assemble the buffer allocated by dma_alloc_attrs() function from individual pages if it can be mapped as contiguous chunk into device dma address space. By specifing this attribute the allocated buffer is forced to be contiguous also in physical memory. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
80 lines
1.8 KiB
C
80 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_SKIP_CPU_SYNC,
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DMA_ATTR_FORCE_CONTIGUOUS,
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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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