qeth: exploit HW TX checksumming

OSA supports HW TX checksumming in layer 3 mode. Enable this
feature and remove software fallback used for TSO. Cleanup
checksum bits to indicate OSA can do checksumming only for
IPv4 TCP and UDP.

Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 69 insertions, 26 deletions

diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h
index fcd005aad98..bab0febf072 100644
--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -351,7 +351,7 @@ enum qeth_header_ids {
 #define QETH_HDR_EXT_SRC_MAC_ADDR     0x08
 #define QETH_HDR_EXT_CSUM_HDR_REQ     0x10
 #define QETH_HDR_EXT_CSUM_TRANSP_REQ  0x20
-#define QETH_HDR_EXT_UDP_TSO          0x40 /*bit off for TCP*/
+#define QETH_HDR_EXT_UDP              0x40 /*bit off for TCP*/
 
 static inline int qeth_is_last_sbale(struct qdio_buffer_element *sbale)
 {
@@ -630,6 +630,7 @@ struct qeth_card_info {
         int unique_id;
         struct qeth_card_blkt blkt;
         __u32 csum_mask;
+        __u32 tx_csum_mask;
         enum qeth_ipa_promisc_modes promisc_mode;
 };
 
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index 35b6d3d2bd7..8bcad24ccf3 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -54,16 +54,16 @@ int qeth_l3_set_large_send(struct qeth_card *card,
         if (card->options.large_send == QETH_LARGE_SEND_TSO) {
                 if (qeth_is_supported(card, IPA_OUTBOUND_TSO)) {
                         card->dev->features |= NETIF_F_TSO | NETIF_F_SG |
-                                        NETIF_F_HW_CSUM;
+                                        NETIF_F_IP_CSUM;
                 } else {
                         card->dev->features &= ~(NETIF_F_TSO | NETIF_F_SG |
-                                        NETIF_F_HW_CSUM);
+                                        NETIF_F_IP_CSUM);
                         card->options.large_send = QETH_LARGE_SEND_NO;
                         rc = -EOPNOTSUPP;
                 }
         } else {
                 card->dev->features &= ~(NETIF_F_TSO | NETIF_F_SG |
-                                        NETIF_F_HW_CSUM);
+                                        NETIF_F_IP_CSUM);
                 card->options.large_send = QETH_LARGE_SEND_NO;
         }
         return rc;
@@ -1108,6 +1108,13 @@ static int qeth_l3_default_setassparms_cb(struct qeth_card *card,
                 card->info.csum_mask = cmd->data.setassparms.data.flags_32bit;
                 QETH_DBF_TEXT_(TRACE, 3, "csum:%d", card->info.csum_mask);
         }
+        if (cmd->data.setassparms.hdr.assist_no == IPA_OUTBOUND_CHECKSUM &&
+            cmd->data.setassparms.hdr.command_code == IPA_CMD_ASS_START) {
+                card->info.tx_csum_mask =
+                        cmd->data.setassparms.data.flags_32bit;
+                QETH_DBF_TEXT_(TRACE, 3, "tcsu:%d", card->info.tx_csum_mask);
+        }
+
         return 0;
 }
 
@@ -1536,6 +1543,28 @@ static int qeth_l3_start_ipa_checksum(struct qeth_card *card)
         return rc;
 }
 
+static int qeth_l3_start_ipa_tx_checksum(struct qeth_card *card)
+{
+        int rc = 0;
+
+        if (!qeth_is_supported(card, IPA_OUTBOUND_CHECKSUM))
+                return rc;
+        rc = qeth_l3_send_simple_setassparms(card, IPA_OUTBOUND_CHECKSUM,
+                          IPA_CMD_ASS_START, 0);
+        if (rc)
+                goto err_out;
+        rc = qeth_l3_send_simple_setassparms(card, IPA_OUTBOUND_CHECKSUM,
+                          IPA_CMD_ASS_ENABLE, card->info.tx_csum_mask);
+        if (rc)
+                goto err_out;
+        dev_info(&card->gdev->dev, "HW TX Checksumming enabled\n");
+        return rc;
+err_out:
+        dev_warn(&card->gdev->dev, "Enabling HW TX checksumming for %s "
+                "failed, using SW TX checksumming\n", QETH_CARD_IFNAME(card));
+        return rc;
+}
+
 static int qeth_l3_start_ipa_tso(struct qeth_card *card)
 {
         int rc;
@@ -1578,6 +1607,7 @@ static int qeth_l3_start_ipassists(struct qeth_card *card)
         qeth_l3_start_ipa_ipv6(card);           /* go on*/
         qeth_l3_start_ipa_broadcast(card);              /* go on*/
         qeth_l3_start_ipa_checksum(card);               /* go on*/
+        qeth_l3_start_ipa_tx_checksum(card);
         qeth_l3_start_ipa_tso(card);            /* go on*/
         return 0;
 }
@@ -2817,6 +2847,21 @@ static void qeth_l3_fill_header(struct qeth_card *card, struct qeth_hdr *hdr,
         }
 }
 
+static inline void qeth_l3_hdr_csum(struct qeth_card *card,
+                struct qeth_hdr *hdr, struct sk_buff *skb)
+{
+        struct iphdr *iph = ip_hdr(skb);
+
+        /* tcph->check contains already the pseudo hdr checksum
+         * so just set the header flags
+         */
+        if (iph->protocol == IPPROTO_UDP)
+                hdr->hdr.l3.ext_flags |= QETH_HDR_EXT_UDP;
+        hdr->hdr.l3.ext_flags |= QETH_HDR_EXT_CSUM_TRANSP_REQ;
+        if (card->options.performance_stats)
+                card->perf_stats.tx_csum++;
+}
+
 static void qeth_tso_fill_header(struct qeth_card *card,
                 struct qeth_hdr *qhdr, struct sk_buff *skb)
 {
@@ -2852,21 +2897,6 @@ static void qeth_tso_fill_header(struct qeth_card *card,
         }
 }
 
-static void qeth_tx_csum(struct sk_buff *skb)
-{
-        __wsum csum;
-        int offset;
-
-        skb_set_transport_header(skb, skb->csum_start - skb_headroom(skb));
-        offset = skb->csum_start - skb_headroom(skb);
-        BUG_ON(offset >= skb_headlen(skb));
-        csum = skb_checksum(skb, offset, skb->len - offset, 0);
-
-        offset += skb->csum_offset;
-        BUG_ON(offset + sizeof(__sum16) > skb_headlen(skb));
-        *(__sum16 *)(skb->data + offset) = csum_fold(csum);
-}
-
 static inline int qeth_l3_tso_elements(struct sk_buff *skb)
 {
         unsigned long tcpd = (unsigned long)tcp_hdr(skb) +
@@ -2923,12 +2953,6 @@ static int qeth_l3_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
         if (skb_is_gso(skb))
                 large_send = card->options.large_send;
-        else
-                if (skb->ip_summed == CHECKSUM_PARTIAL) {
-                        qeth_tx_csum(skb);
-                        if (card->options.performance_stats)
-                                card->perf_stats.tx_csum++;
-                }
 
         if ((card->info.type == QETH_CARD_TYPE_IQD) && (!large_send) &&
             (skb_shinfo(skb)->nr_frags == 0)) {
@@ -3007,6 +3031,9 @@ static int qeth_l3_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
                                                 cast_type);
                         hdr->hdr.l3.length = new_skb->len - data_offset;
                 }
+
+                if (skb->ip_summed == CHECKSUM_PARTIAL)
+                        qeth_l3_hdr_csum(card, hdr, new_skb);
         }
 
         elems = qeth_get_elements_no(card, (void *)hdr, new_skb,
@@ -3132,10 +3159,25 @@ static int qeth_l3_ethtool_set_tso(struct net_device *dev, u32 data)
         return rc;
 }
 
+static int qeth_l3_ethtool_set_tx_csum(struct net_device *dev, u32 data)
+{
+        struct qeth_card *card = dev->ml_priv;
+
+        if (data) {
+                if (qeth_is_supported(card, IPA_OUTBOUND_CHECKSUM))
+                        dev->features |= NETIF_F_IP_CSUM;
+                else
+                        return -EPERM;
+        } else
+                dev->features &= ~NETIF_F_IP_CSUM;
+
+        return 0;
+}
+
 static const struct ethtool_ops qeth_l3_ethtool_ops = {
         .get_link = ethtool_op_get_link,
         .get_tx_csum = ethtool_op_get_tx_csum,
-        .set_tx_csum = ethtool_op_set_tx_hw_csum,
+        .set_tx_csum = qeth_l3_ethtool_set_tx_csum,
         .get_rx_csum = qeth_l3_ethtool_get_rx_csum,
         .set_rx_csum = qeth_l3_ethtool_set_rx_csum,
         .get_sg      = ethtool_op_get_sg,