1 files changed, 60 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/pci-dma.c b/arch/x86_64/kernel/pci-dma.c
new file mode 100644
index 000000000000..cab471cf3edb
--- /dev/null
+++ b/arch/x86_64/kernel/pci-dma.c
@@ -0,0 +1,60 @@
+/*
+ * Dynamic DMA mapping support.
+ */
+
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/pci.h>
+#include <linux/module.h>
+#include <asm/io.h>
+
+/* Map a set of buffers described by scatterlist in streaming
+ * mode for DMA.  This is the scatter-gather version of the
+ * above pci_map_single interface.  Here the scatter gather list
+ * elements are each tagged with the appropriate dma address
+ * and length.  They are obtained via sg_dma_{address,length}(SG).
+ *
+ * NOTE: An implementation may be able to use a smaller number of
+ *       DMA address/length pairs than there are SG table elements.
+ *       (for example via virtual mapping capabilities)
+ *       The routine returns the number of addr/length pairs actually
+ *       used, at most nents.
+ *
+ * Device ownership issues as mentioned above for pci_map_single are
+ * the same here.
+ */
+int dma_map_sg(struct device *hwdev, struct scatterlist *sg,
+               int nents, int direction)
+{
+        int i;
+
+        BUG_ON(direction == DMA_NONE);
+        for (i = 0; i < nents; i++ ) {
+                struct scatterlist *s = &sg[i];
+                BUG_ON(!s->page); 
+                s->dma_address = virt_to_bus(page_address(s->page) +s->offset);
+                s->dma_length = s->length;
+        }
+        return nents;
+}
+
+EXPORT_SYMBOL(dma_map_sg);
+
+/* Unmap a set of streaming mode DMA translations.
+ * Again, cpu read rules concerning calls here are the same as for
+ * pci_unmap_single() above.
+ */
+void dma_unmap_sg(struct device *dev, struct scatterlist *sg,
+                  int nents, int dir)
+{
+        int i;
+        for (i = 0; i < nents; i++) { 
+                struct scatterlist *s = &sg[i];
+                BUG_ON(s->page == NULL); 
+                BUG_ON(s->dma_address == 0); 
+                dma_unmap_single(dev, s->dma_address, s->dma_length, dir);
+        } 
+}
+
+EXPORT_SYMBOL(dma_unmap_sg);