Document the new dma_{un}map_{single|sg}_attrs() functions.
Signed-off-by: Arthur Kepner <[EMAIL PROTECTED]>
--
DMA-API.txt | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 63 insertions(+)
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index b939ebb..fad05e0 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -395,6 +395,69 @@ Notes: You must do this:
See also dma_map_single().
+dma_addr_t
+dma_map_single_attrs(struct device *dev, void *cpu_addr, size_t size,
+ enum dma_data_direction dir,
+ struct dma_attrs* attrs)
+
+void
+dma_unmap_single_attrs(struct device *dev, dma_addr_t dma_addr,
+ size_t size, enum dma_data_direction dir,
+ struct dma_attrs* attrs)
+
+int
+dma_map_sg_attrs(struct device *dev, struct scatterlist *sgl,
+ int nents, enum dma_data_direction dir,
+ struct dma_attrs *attrs)
+
+void
+dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sgl,
+ int nents, enum dma_data_direction dir,
+ struct dma_attrs *attrs)
+
+The four functions above are just like the counterpart functions
+without the _attrs suffixes, except that they pass an optional
+struct dma_attrs*.
+
+struct dma_attrs encapsulates a set of "dma attributes". For the
+definition of struct dma_attrs see linux/dma-attrs.h.
+
+The interpretation of dma attributes is architecture-specific.
+
+If struct dma_attrs* is NULL, the semantics of each of these
+functions is identical to those of the corresponding function
+without the _attrs suffix. As a result dma_map_single_attrs()
+can generally replace dma_map_single(), etc.
+
+As an example of the use of the *_attrs functions, here's how
+you could pass an attribute DMA_ATTR_FOO when mapping memory
+for DMA:
+
+#include <linux/dma-attrs.h>
+/* DMA_ATTR_FOO should be defined in linux/dma-attrs.h */
+...
+
+ DECLARE_DMA_ATTRS(attrs);
+ dma_set_attr(&attrs, DMA_ATTR_FOO);
+ ....
+ n = dma_map_sg_attrs(dev, sg, nents, DMA_TO_DEVICE, &attr);
+ ....
+
+Architectures that care about DMA_ATTR_FOO would check for its
+presence in their implementations of the mapping and unmapping
+routines, e.g.:
+
+void whizco_dma_map_sg_attrs(struct device *dev, dma_addr_t dma_addr,
+ size_t size, enum dma_data_direction dir,
+ struct dma_attrs* attrs)
+{
+ ....
+ int foo = dma_get_attr(attrs, DMA_ATTR_FOO);
+ ....
+ if (foo)
+ /* twizzle the frobnozzle */
+ ....
+
Part II - Advanced dma_ usage
-----------------------------
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