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_maps[0] = 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 + 1] = map;
  32         }
  33         sp->num_dma_maps = i + 1;
  34
  35         return 0;
  36
  37 unwind:
  38         while (--i >= 0) {
  39                 skb_frag_t *fp = &sp->frags[i];
  40
  41                 dma_unmap_page(dev, sp->dma_maps[i + 1],
  42                                fp->size, dir);
  43         }
  44         dma_unmap_single(dev, sp->dma_maps[0],
  45                          skb_headlen(skb), dir);
  46 out_err:
  47         return -ENOMEM;
  48 }
  49 EXPORT_SYMBOL(skb_dma_map);
  50
  51 void skb_dma_unmap(struct device *dev, struct sk_buff *skb,
  52                    enum dma_data_direction dir)
  53 {
  54         struct skb_shared_info *sp = skb_shinfo(skb);
  55         int i;
  56
  57         dma_unmap_single(dev, sp->dma_maps[0],
  58                          skb_headlen(skb), dir);
  59         for (i = 0; i < sp->nr_frags; i++) {
  60                 skb_frag_t *fp = &sp->frags[i];
  61
  62                 dma_unmap_page(dev, sp->dma_maps[i + 1],
  63                                fp->size, dir);
  64         }
  65 }
  66 EXPORT_SYMBOL(skb_dma_unmap);