net: Add SKB DMA mapping helper functions.

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 67 insertions, 0 deletions

diff --git a/net/core/Makefile b/net/core/Makefile
index b1332f6d0042..26a37cb31923 100644
--- a/net/core/Makefile
+++ b/net/core/Makefile
@@ -6,6 +6,7 @@ obj-y := sock.o request_sock.o skbuff.o iovec.o datagram.o stream.o scm.o \
          gen_stats.o gen_estimator.o net_namespace.o
 
 obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
+obj-$(CONFIG_HAS_DMA) += skb_dma_map.o
 
 obj-y                += dev.o ethtool.o dev_mcast.o dst.o netevent.o \
                         neighbour.o rtnetlink.o utils.o link_watch.o filter.o
diff --git a/net/core/skb_dma_map.c b/net/core/skb_dma_map.c
new file mode 100644
index 000000000000..1f49afcd8e86
--- /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);