x86: implement dma_map_single through dma_ops

That's already the name of the game for x86_64. For i386,
we add a pci-base_32.c, that will hold the default operations.
The function call itself goes through dma-mapping.h , the common
header

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/Makefile

@@ -26,6 +26,7 @@ obj-y			+= pci-dma_$(BITS).o  bootflag.o e820_$(BITS).o
 obj-y			+= quirks.o i8237.o topology.o kdebugfs.o
 obj-y			+= alternative.o i8253.o
 obj-$(CONFIG_X86_64)	+= pci-nommu_64.o bugs_64.o
+obj-$(CONFIG_X86_32)	+= pci-base_32.o
 obj-y			+= tsc_$(BITS).o io_delay.o rtc.o
 
 obj-$(CONFIG_X86_TRAMPOLINE)	+= trampoline.o

arch/x86/kernel/pci-base_32.c

@@ -0,0 +1,20 @@
+#include <linux/mm.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/dma-mapping.h>
+#include <asm/dma-mapping.h>
+
+static dma_addr_t pci32_map_single(struct device *dev, void *ptr,
+				   size_t size, int direction)
+{
+	WARN_ON(size == 0);
+	flush_write_buffers();
+	return virt_to_phys(ptr);
+}
+
+static const struct dma_mapping_ops pci32_dma_ops = {
+	.map_single = pci32_map_single,
+};
+
+const struct dma_mapping_ops *dma_ops = &pci32_dma_ops;
+EXPORT_SYMBOL(dma_ops);

include/asm-x86/dma-mapping.h

@@ -50,10 +50,20 @@ struct dma_mapping_ops {
 	int		is_phys;
 };
 
+extern const struct dma_mapping_ops *dma_ops;
+
 #ifdef CONFIG_X86_32
 # include "dma-mapping_32.h"
 #else
 # include "dma-mapping_64.h"
 #endif
 
+static inline dma_addr_t
+dma_map_single(struct device *hwdev, void *ptr, size_t size,
+	       int direction)
+{
+	BUG_ON(!valid_dma_direction(direction));
+	return dma_ops->map_single(hwdev, ptr, size, direction);
+}
+
 #endif

include/asm-x86/dma-mapping_32.h

@@ -17,16 +17,6 @@ void *dma_alloc_coherent(struct device *dev, size_t size,
 void dma_free_coherent(struct device *dev, size_t size,
 			 void *vaddr, dma_addr_t dma_handle);
 
-static inline dma_addr_t
-dma_map_single(struct device *dev, void *ptr, size_t size,
-	       enum dma_data_direction direction)
-{
-	BUG_ON(!valid_dma_direction(direction));
-	WARN_ON(size == 0);
-	flush_write_buffers();
-	return virt_to_phys(ptr);
-}
-
 static inline void
 dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 		 enum dma_data_direction direction)

include/asm-x86/dma-mapping_64.h

@@ -2,7 +2,6 @@
 #define _X8664_DMA_MAPPING_H 1
 
 extern dma_addr_t bad_dma_address;
-extern const struct dma_mapping_ops* dma_ops;
 extern int iommu_merge;
 
 static inline int dma_mapping_error(dma_addr_t dma_addr)
@@ -24,14 +23,6 @@ extern void *dma_alloc_coherent(struct device *dev, size_t size,
 extern void dma_free_coherent(struct device *dev, size_t size, void *vaddr,
 			      dma_addr_t dma_handle);
 
-static inline dma_addr_t
-dma_map_single(struct device *hwdev, void *ptr, size_t size,
-	       int direction)
-{
-	BUG_ON(!valid_dma_direction(direction));
-	return dma_ops->map_single(hwdev, ptr, size, direction);
-}
-
 static inline void
 dma_unmap_single(struct device *dev, dma_addr_t addr,size_t size,
 		 int direction)