Title: [7670] branches/2009R1/drivers/net/bfin_mac.c: Task[#5621] Deduce Ethernet FCS from hardware IP payload checksum.
- Revision
- 7670
- Author
- sonicz
- Date
- 2009-10-19 04:57:16 -0400 (Mon, 19 Oct 2009)
Log Message
Task[#5621] Deduce Ethernet FCS from hardware IP payload checksum.
IP checksum is based on 16-bit one's complement algorithm.
To deduce a value from checksum is equal to add its complement.
Modified Paths
Diff
Modified: branches/2009R1/drivers/net/bfin_mac.c (7669 => 7670)
--- branches/2009R1/drivers/net/bfin_mac.c 2009-10-16 12:35:20 UTC (rev 7669)
+++ branches/2009R1/drivers/net/bfin_mac.c 2009-10-19 08:57:16 UTC (rev 7670)
@@ -675,10 +675,16 @@
return 0;
}
+#define ETH_FCS_LENGTH 4
+
static void bfin_mac_rx(struct net_device *dev)
{
struct sk_buff *skb, *new_skb;
unsigned short len;
+#if defined(BFIN_MAC_CSUM_OFFLOAD)
+ unsigned int i;
+ unsigned char fcs[ETH_FCS_LENGTH];
+#endif
/* allocate a new skb for next time receive */
skb = current_rx_ptr->skb;
@@ -701,12 +707,22 @@
current_rx_ptr->desc_a.start_addr = (unsigned long)new_skb->data - 2;
len = (unsigned short)((current_rx_ptr->status.status_word) & RX_FRLEN);
+ /* Deduce Ethernet FCS length from Ethernet payload length */
+ len -= ETH_FCS_LENGTH;
skb_put(skb, len);
dev->last_rx = jiffies;
skb->protocol = eth_type_trans(skb, dev);
#if defined(BFIN_MAC_CSUM_OFFLOAD)
skb->csum = current_rx_ptr->status.ip_payload_csum;
+ /*
+ * Deduce Ethernet FCS from hardware generated IP payload checksum.
+ * IP checksum is based on 16-bit one's complement algorithm.
+ * To deduce a value from checksum is equal to add its complement.
+ */
+ for (i = 0; i < ETH_FCS_LENGTH; i++)
+ fcs[i] = ~skb->data[skb->len + i];
+ skb->csum = csum_partial(fcs, ETH_FCS_LENGTH, skb->csum);
skb->ip_summed = CHECKSUM_COMPLETE;
#endif
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