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authorArthur Kepner <akepner@sgi.com>2008-04-29 12:00:30 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-29 19:06:11 +0400
commit74bc7ceebfa1c84ddd3a843ebfb56df013bf7ef5 (patch)
tree548155250fbc7410273125019c70a7c5c085e895 /include/linux/dma-attrs.h
parentd2ba7e2ae206e9ab24e8937d99d0d5513bfd08e5 (diff)
downloadlinux-74bc7ceebfa1c84ddd3a843ebfb56df013bf7ef5.tar.xz
dma: add dma_*map*_attrs() interfaces
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>
Diffstat (limited to 'include/linux/dma-attrs.h')
-rw-r--r--include/linux/dma-attrs.h74
1 files changed, 74 insertions, 0 deletions
diff --git a/include/linux/dma-attrs.h b/include/linux/dma-attrs.h
new file mode 100644
index 000000000000..1677e2bfa00c
--- /dev/null
+++ b/include/linux/dma-attrs.h
@@ -0,0 +1,74 @@
+#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_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 */