net/core/skb_dma_map.c

   1 /* skb_dma_map.c: DMA mapping helpers for socket buffers.
   2  *
   3  * Copyright (C) David S. Miller <davem@davemloft.net>
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/module.h>
   8 #include <linux/dma-mapping.h>
   9 #include <linux/skbuff.h>
  10
  11 int skb_dma_map(struct device *dev, struct sk_buff *skb,
  12                 enum dma_data_direction dir)
  13 {
  14         struct skb_shared_info *sp = skb_shinfo(skb);
  15         dma_addr_t map;
  16         int i;
  17
  18         map = dma_map_single(dev, skb->data,
  19                              skb_headlen(skb), dir);
  20         if (dma_mapping_error(dev, map))
  21                 goto out_err;
  22
  23         sp->dma_head = map;
  24         for (i = 0; i < sp->nr_frags; i++) {
  25                 skb_frag_t *fp = &sp->frags[i];
  26
  27                 map = dma_map_page(dev, fp->page, fp->page_offset,
  28                                    fp->size, dir);
  29                 if (dma_mapping_error(dev, map))
  30                         goto unwind;
  31                 sp->dma_maps[i] = map;
  32         }
  33
  34         return 0;
  35
  36 unwind:
  37         while (--i >= 0) {
  38                 skb_frag_t *fp = &sp->frags[i];
  39
  40                 dma_unmap_page(dev, sp->dma_maps[i],
  41                                fp->size, dir);
  42         }
  43         dma_unmap_single(dev, sp->dma_head,
  44                          skb_headlen(skb), dir);
  45 out_err:
  46         return -ENOMEM;
  47 }
  48 EXPORT_SYMBOL(skb_dma_map);
  49
  50 void skb_dma_unmap(struct device *dev, struct sk_buff *skb,
  51                    enum dma_data_direction dir)
  52 {
  53         struct skb_shared_info *sp = skb_shinfo(skb);
  54         int i;
  55
  56         dma_unmap_single(dev, sp->dma_head,
  57                          skb_headlen(skb), dir);
  58         for (i = 0; i < sp->nr_frags; i++) {
  59                 skb_frag_t *fp = &sp->frags[i];
  60
  61                 dma_unmap_page(dev, sp->dma_maps[i],
  62                                fp->size, dir);
  63         }
  64 }
  65 EXPORT_SYMBOL(skb_dma_unmap);