net: Add SKB DMA mapping helper functions.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/skb_dma_map.c b/net/core/skb_dma_map.c
new file mode 100644
index 0000000..1f49afc
--- /dev/null
+++ b/net/core/skb_dma_map.c
@@ -0,0 +1,66 @@
+/* skb_dma_map.c: DMA mapping helpers for socket buffers.
+ *
+ * Copyright (C) David S. Miller <davem@davemloft.net>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/dma-mapping.h>
+#include <linux/skbuff.h>
+
+int skb_dma_map(struct device *dev, struct sk_buff *skb,
+ enum dma_data_direction dir)
+{
+ struct skb_shared_info *sp = skb_shinfo(skb);
+ dma_addr_t map;
+ int i;
+
+ map = dma_map_single(dev, skb->data,
+ skb_headlen(skb), dir);
+ if (dma_mapping_error(dev, map))
+ goto out_err;
+
+ sp->dma_maps[0] = map;
+ for (i = 0; i < sp->nr_frags; i++) {
+ skb_frag_t *fp = &sp->frags[i];
+
+ map = dma_map_page(dev, fp->page, fp->page_offset,
+ fp->size, dir);
+ if (dma_mapping_error(dev, map))
+ goto unwind;
+ sp->dma_maps[i + 1] = map;
+ }
+ sp->num_dma_maps = i + 1;
+
+ return 0;
+
+unwind:
+ while (i-- >= 0) {
+ skb_frag_t *fp = &sp->frags[i];
+
+ dma_unmap_page(dev, sp->dma_maps[i + 1],
+ fp->size, dir);
+ }
+ dma_unmap_single(dev, sp->dma_maps[0],
+ skb_headlen(skb), dir);
+out_err:
+ return -ENOMEM;
+}
+EXPORT_SYMBOL(skb_dma_map);
+
+void skb_dma_unmap(struct device *dev, struct sk_buff *skb,
+ enum dma_data_direction dir)
+{
+ struct skb_shared_info *sp = skb_shinfo(skb);
+ int i;
+
+ dma_unmap_single(dev, sp->dma_maps[0],
+ skb_headlen(skb), dir);
+ for (i = 0; i < sp->nr_frags; i++) {
+ skb_frag_t *fp = &sp->frags[i];
+
+ dma_unmap_page(dev, sp->dma_maps[i + 1],
+ fp->size, dir);
+ }
+}
+EXPORT_SYMBOL(skb_dma_unmap);