[PATCH] rx checksum support for gige nForce ethernet

[Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>]

Hi,

With help from nVidia I have added rx checksumming to the forcedeth 
driver. It's only supported by the gigabit version of the chipset.

Please test it - it works for me. Depends on the previous patches to 
2.6.8-rc3-mm1, but rejects against 2.6.8-rc3-mm1 should be trivial.

--
   Manfred

// $Header$
// Kernel Version:
//  VERSION = 2
//  PATCHLEVEL = 6
//  SUBLEVEL = 8
//  EXTRAVERSION =-rc3-mm1
--- 2.6/drivers/net/forcedeth.c 2004-08-07 13:09:21.512115128 +0200
+++ build-2.6/drivers/net/forcedeth.c   2004-08-07 13:15:37.308985320 +0200
@@ -78,6 +78,7 @@
  *     0.29: 28 Jul 2004: Add jumbo frame support. Add reset into nv_close,
  *                        previous code clobbered kfree'd memory.
  *     0.30: 07 Aug 2004: Add backup timer for link change notification.
+ *     0.31: 07 Aug 2004: rx checksum support
  *
  * Known bugs:
  * We suspect that on some hardware no TX done interrupts are generated.
@@ -89,7 +90,7 @@
  * DEV_NEED_TIMERIRQ will not harm you on sane hardware, only generating a few
  * superfluous timer interrupts from the nic.
  */
-#define FORCEDETH_VERSION              "0.30"
+#define FORCEDETH_VERSION              "0.31"
 #define DRV_NAME                       "forcedeth"
 
 #include <linux/module.h>
@@ -219,6 +220,7 @@ enum {
 #define NVREG_TXRXCTL_BIT2     0x0004
 #define NVREG_TXRXCTL_IDLE     0x0008
 #define NVREG_TXRXCTL_RESET    0x0010
+#define NVREG_TXRXCTL_RXCHECK  0x0400
        NvRegMIIStatus = 0x180,
 #define NVREG_MIISTAT_ERROR            0x0001
 #define NVREG_MIISTAT_LINKCHANGE       0x0008
@@ -315,6 +317,10 @@ struct ring_desc {
 #define NV_RX_ERROR            (1<<30)
 #define NV_RX_AVAIL            (1<<31)
 
+#define NV_RX2_CHECKSUMMASK    (0x1C000000)
+#define NV_RX2_CHECKSUMOK1     (0x10000000)
+#define NV_RX2_CHECKSUMOK2     (0x14000000)
+#define NV_RX2_CHECKSUMOK3     (0x18000000)
 #define NV_RX2_DESCRIPTORVALID (1<<29)
 #define NV_RX2_SUBSTRACT1      (1<<25)
 #define NV_RX2_ERROR1          (1<<18)
@@ -377,8 +383,15 @@ struct ring_desc {
 #define POLL_WAIT      (1+HZ/100)
 #define LINK_TIMEOUT   (3*HZ)
 
+/* 
+ * desc_ver values:
+ * This field has two purposes:
+ * - Newer nics uses a different ring layout. The layout is selected by
+ *   comparing np->desc_ver with DESC_VER_xy.
+ * - It contains bits that are forced on when writing to NvRegTxRxControl.
+ */
 #define DESC_VER_1     0x0
-#define DESC_VER_2     0x02100
+#define DESC_VER_2     (0x02100|NVREG_TXRXCTL_RXCHECK)
 
 /* PHY defines */
 #define PHY_OUI_MARVELL        0x5043
@@ -1200,6 +1213,15 @@ static void nv_rx_process(struct net_dev
                                        goto next_pkt;
                                }
                        }
+                       Flags &= NV_RX2_CHECKSUMMASK;
+                       if (Flags == NV_RX2_CHECKSUMOK1 ||
+                                       Flags == NV_RX2_CHECKSUMOK2 ||
+                                       Flags == NV_RX2_CHECKSUMOK3) {
+                               dprintk(KERN_DEBUG "%s: hw checksum hit!.\n", 
dev->name);
+                               np->rx_skbuff[i]->ip_summed = 
CHECKSUM_UNNECESSARY;
+                       } else {
+                               dprintk(KERN_DEBUG "%s: hwchecksum miss!.\n", 
dev->name);
+                       }
                }
                /* got a valid packet - forward it to the network core */
                skb = np->rx_skbuff[i];