74bc7ceebf
Introduce new interfaces, dma_*map*_attrs(), for passing architecture-specific
attributes when memory is mapped and unmapped for DMA. Give the interfaces
default implementations which ignore attributes. Also introduce the
dma_{set|get}_attr() interfaces for setting and retrieving individual
attributes. Define one attribute, DMA_ATTR_WRITE_BARRIER, in anticipation of
its use by ia64/sn. Select whether architectures implement arch-specific
versions of the dma_*map*_attrs() interfaces via HAVE_DMA_ATTRS in Kconfig.
[markn@au1.ibm.com: dma_{set,get}_attr() have to be static inline]
Signed-off-by: Arthur Kepner <akepner@sgi.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Jes Sorensen <jes@sgi.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Roland Dreier <rdreier@cisco.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: David Miller <davem@davemloft.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Grant Grundler <grundler@parisc-linux.org>
Cc: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Mark Nelson <markn@au1.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
74 lines
1.7 KiB
C
74 lines
1.7 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_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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