x86: introduce pci-dma.c

This patch introduces pci-dma.c, a common file for pci dma
between i386 and x86_64. As a start, dma_set_mask() is the same
between architectures, and is placed there.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
new file mode 100644
index 0000000..f1c24d8
--- /dev/null
+++ b/arch/x86/kernel/pci-dma.c
@@ -0,0 +1,14 @@
+#include <linux/dma-mapping.h>
+
+int dma_set_mask(struct device *dev, u64 mask)
+{
+	if (!dev->dma_mask || !dma_supported(dev, mask))
+		return -EIO;
+
+	*dev->dma_mask = mask;
+
+	return 0;
+}
+EXPORT_SYMBOL(dma_set_mask);
+
+