[PATCH 0/3 v6] dma: add dma_*map*_attrs() interfaces

[akepner]

v5-v6 changes:

- if CONFIG_HAVE_DMA_ATTRS isn't defined , use macros to 
  define dma_*map*_attrs() - this gets around a build problem 
  on alpha, and maybe other arches, too.

- fix ib_umem_get() call in drivers/infiniband/hw/nes/nes_verbs.c

--- 

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.

Signed-off-by: Arthur Kepner <akepner@xxxxxxx>

---

 arch/Kconfig                |    3 +
 arch/ia64/Kconfig           |    1 
 include/linux/dma-attrs.h   |   74 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/dma-mapping.h |   17 ++++++++++
 4 files changed, 95 insertions(+)

diff --git a/arch/Kconfig b/arch/Kconfig
index 694c9af..3ea332b 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -36,3 +36,6 @@ config HAVE_KPROBES
 
 config HAVE_KRETPROBES
 	def_bool n
+
+config HAVE_DMA_ATTRS
+	def_bool n
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 8fa3faf..985b267 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -19,6 +19,7 @@ config IA64
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
+	select HAVE_DMA_ATTRS
 	default y
 	help
 	  The Itanium Processor Family is Intel's 64-bit successor to
diff --git a/include/linux/dma-attrs.h b/include/linux/dma-attrs.h
index e69de29..5f151fb 100644
--- a/include/linux/dma-attrs.h
+++ 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)
+ */
+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)
+ */
+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 */
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 3320307..952e0f8 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -146,4 +146,21 @@ static inline void dmam_release_declared_memory(struct device *dev)
 }
 #endif /* ARCH_HAS_DMA_DECLARE_COHERENT_MEMORY */
 
+#ifndef CONFIG_HAVE_DMA_ATTRS
+struct dma_attrs;
+
+#define dma_map_single_attrs(dev, cpu_addr, size, dir, attrs) \
+	dma_map_single(dev, cpu_addr, size, dir)
+
+#define dma_unmap_single_attrs(dev, dma_addr, size, dir, attrs) \
+	dma_unmap_single(dev, dma_addr, size, dir)
+
+#define dma_map_sg_attrs(dev, sgl, nents, dir, attrs) \
+	dma_map_sg(dev, sgl, nents, dir)
+
+#define dma_unmap_sg_attrs(dev, sgl, nents, dir, attrs) \
+	dma_unmap_sg(dev, sgl, nents, dir)
+
+#endif /* CONFIG_HAVE_DMA_ATTRS */
+
 #endif
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