dma: add dma_*map*_attrs() interfaces

v4-v5 changes:

- select HAVE_DMA_ATTRS via Kconfig
- changed the name DMA_ATTR_BARRIER to DMA_ATTR_WRITE_BARRIER
- changed struct dma_attrs to be a wrapper around a bitmap
- kernel-doc-ified some comments
- recombined the lib/swiotlb.c patch into the ia64-arch patch (they need to go in together, or other forward decls are needed)

---

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.

---

 arch/Kconfig                |    3 +
 arch/ia64/Kconfig           |    1 
 include/linux/dma-attrs.h   |   74 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/dma-mapping.h |   35 ++++++++++++++++++++
 4 files changed, 113 insertions(+)

index 694c9af..3ea332b 100644
@@ -36,3 +36,6 @@ config HAVE_KPROBES
 
 config HAVE_KRETPROBES
 	def_bool n
+
+config HAVE_DMA_ATTRS
+	def_bool n

index 8fa3faf..985b267 100644
@@ -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

index 3320307..f757d63 100644
@@ -146,4 +146,39 @@ 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;
+
+static inline 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)
+{
+	return dma_map_single(dev, cpu_addr, size, dir);
+}
+
+static inline 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)
+{
+	return dma_unmap_single(dev, dma_addr, size, dir);
+}
+
+static inline int dma_map_sg_attrs(struct device *dev, struct scatterlist *sgl,
+				   int nents, enum dma_data_direction dir,
+				   struct dma_attrs *attrs)
+{
+	return dma_map_sg(dev, sgl, nents, dir);
+}
+
+static inline void dma_unmap_sg_attrs(struct device *dev,
+				      struct scatterlist *sgl, int nents,
+				      enum dma_data_direction dir,
+				      struct dma_attrs *attrs)
+{
+	return dma_unmap_sg(dev, sgl, nents, dir);
+}
+#endif /* CONFIG_HAVE_DMA_ATTRS */
+
 #endif

alpha allmodconfig:

In file included from include/asm/pci.h:7,

                 from include/linux/pci.h:953,
                 from include/asm/core_mcpcia.h:9,
                 from include/asm/io.h:226,
                 from arch/alpha/kernel/asm-offsets.c:11:

include/linux/dma-mapping.h: In function 'dma_map_single_attrs':
include/linux/dma-mapping.h:157: error: implicit declaration of function 'pci_map_single' include/linux/dma-mapping.h:157: error: implicit declaration of function 'alpha_gendev_to_pci' include/linux/dma-mapping.h: In function 'dma_unmap_single_attrs':
include/linux/dma-mapping.h:165: error: implicit declaration of function 'pci_unmap_single' include/linux/dma-mapping.h:165: warning: 'return' with a value, in function returning void include/linux/dma-mapping.h: In function 'dma_map_sg_attrs':
include/linux/dma-mapping.h:172: error: implicit declaration of function 'pci_map_sg' include/linux/dma-mapping.h: In function 'dma_unmap_sg_attrs':
include/linux/dma-mapping.h:180: error: implicit declaration of function 'pci_unmap_sg' include/linux/dma-mapping.h:180: warning: 'return' with a value, in function returning void In file included from include/linux/pci.h:953,

                 from include/asm/core_mcpcia.h:9,
                 from include/asm/io.h:226,
                 from arch/alpha/kernel/asm-offsets.c:11:

We're in include hell, I think. alpha defined CONFIG_HAS_DMA, so it has already included asm/dma-mapping.h, which defines pci_map_single(). But I suspect that the compiler skipped that inclusion because it was recursive. Or something.

I will point you at http://userweb.kernel.org/~akpm/cross-compilers/ and run away, sorry.

Yeah.

Alpha did some macro substitutions differently than on the other platforms I had built and tested with.

The simple fix is to convert the new _attrs()* functions in include/linux/dma-mapping.h into macros.

An updated patch follows. Built for alpha, ia64, x86_64. Tested on ia64 and x86_64.

Arthur