net-next: dsa: add Qualcomm tag RX/TX handler

Add support for the 2-bytes Qualcomm tag that gigabit switches such as
the QCA8337/N might insert when receiving packets, or that we need
to insert while targeting specific switch ports. The tag is inserted
directly behind the ethernet header.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: John Crispin <john@phrozen.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 147 insertions, 0 deletions

diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
index ff7736f7ff42..96e47c539bee 100644
--- a/net/dsa/Kconfig
+++ b/net/dsa/Kconfig
@@ -38,4 +38,7 @@ config NET_DSA_TAG_EDSA
 config NET_DSA_TAG_TRAILER
         bool
 
+config NET_DSA_TAG_QCA
+        bool
+
 endif
diff --git a/net/dsa/Makefile b/net/dsa/Makefile
index 8af4ded70f1c..a3380ed0e0be 100644
--- a/net/dsa/Makefile
+++ b/net/dsa/Makefile
@@ -7,3 +7,4 @@ dsa_core-$(CONFIG_NET_DSA_TAG_BRCM) += tag_brcm.o
 dsa_core-$(CONFIG_NET_DSA_TAG_DSA) += tag_dsa.o
 dsa_core-$(CONFIG_NET_DSA_TAG_EDSA) += tag_edsa.o
 dsa_core-$(CONFIG_NET_DSA_TAG_TRAILER) += tag_trailer.o
+dsa_core-$(CONFIG_NET_DSA_TAG_QCA) += tag_qca.o
diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index d8d267e9a872..66e31acfcad8 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -54,6 +54,9 @@ const struct dsa_device_ops *dsa_device_ops[DSA_TAG_LAST] = {
 #ifdef CONFIG_NET_DSA_TAG_BRCM
         [DSA_TAG_PROTO_BRCM] = &brcm_netdev_ops,
 #endif
+#ifdef CONFIG_NET_DSA_TAG_QCA
+        [DSA_TAG_PROTO_QCA] = &qca_netdev_ops,
+#endif
         [DSA_TAG_PROTO_NONE] = &none_ops,
 };
 
diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index 00077a9c97f4..6cfd7388834e 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -81,5 +81,7 @@ extern const struct dsa_device_ops trailer_netdev_ops;
 /* tag_brcm.c */
 extern const struct dsa_device_ops brcm_netdev_ops;
 
+/* tag_qca.c */
+extern const struct dsa_device_ops qca_netdev_ops;
 
 #endif
diff --git a/net/dsa/tag_qca.c b/net/dsa/tag_qca.c
new file mode 100644
index 000000000000..0c90cacee7aa
--- /dev/null
+++ b/net/dsa/tag_qca.c
@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) 2015, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/etherdevice.h>
+#include "dsa_priv.h"
+
+#define QCA_HDR_LEN     2
+#define QCA_HDR_VERSION 0x2
+
+#define QCA_HDR_RECV_VERSION_MASK       GENMASK(15, 14)
+#define QCA_HDR_RECV_VERSION_S          14
+#define QCA_HDR_RECV_PRIORITY_MASK      GENMASK(13, 11)
+#define QCA_HDR_RECV_PRIORITY_S         11
+#define QCA_HDR_RECV_TYPE_MASK          GENMASK(10, 6)
+#define QCA_HDR_RECV_TYPE_S             6
+#define QCA_HDR_RECV_FRAME_IS_TAGGED    BIT(3)
+#define QCA_HDR_RECV_SOURCE_PORT_MASK   GENMASK(2, 0)
+
+#define QCA_HDR_XMIT_VERSION_MASK       GENMASK(15, 14)
+#define QCA_HDR_XMIT_VERSION_S          14
+#define QCA_HDR_XMIT_PRIORITY_MASK      GENMASK(13, 11)
+#define QCA_HDR_XMIT_PRIORITY_S         11
+#define QCA_HDR_XMIT_CONTROL_MASK       GENMASK(10, 8)
+#define QCA_HDR_XMIT_CONTROL_S          8
+#define QCA_HDR_XMIT_FROM_CPU           BIT(7)
+#define QCA_HDR_XMIT_DP_BIT_MASK        GENMASK(6, 0)
+
+static struct sk_buff *qca_tag_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+        struct dsa_slave_priv *p = netdev_priv(dev);
+        u16 *phdr, hdr;
+
+        dev->stats.tx_packets++;
+        dev->stats.tx_bytes += skb->len;
+
+        if (skb_cow_head(skb, 0) < 0)
+                goto out_free;
+
+        skb_push(skb, QCA_HDR_LEN);
+
+        memmove(skb->data, skb->data + QCA_HDR_LEN, 2 * ETH_ALEN);
+        phdr = (u16 *)(skb->data + 2 * ETH_ALEN);
+
+        /* Set the version field, and set destination port information */
+        hdr = QCA_HDR_VERSION << QCA_HDR_XMIT_VERSION_S |
+                QCA_HDR_XMIT_FROM_CPU |
+                BIT(p->port);
+
+        *phdr = htons(hdr);
+
+        return skb;
+
+out_free:
+        kfree_skb(skb);
+        return NULL;
+}
+
+static int qca_tag_rcv(struct sk_buff *skb, struct net_device *dev,
+                       struct packet_type *pt, struct net_device *orig_dev)
+{
+        struct dsa_switch_tree *dst = dev->dsa_ptr;
+        struct dsa_switch *ds;
+        u8 ver;
+        int port;
+        __be16 *phdr, hdr;
+
+        if (unlikely(!dst))
+                goto out_drop;
+
+        skb = skb_unshare(skb, GFP_ATOMIC);
+        if (!skb)
+                goto out;
+
+        if (unlikely(!pskb_may_pull(skb, QCA_HDR_LEN)))
+                goto out_drop;
+
+        /* The QCA header is added by the switch between src addr and Ethertype
+         * At this point, skb->data points to ethertype so header should be
+         * right before
+         */
+        phdr = (__be16 *)(skb->data - 2);
+        hdr = ntohs(*phdr);
+
+        /* Make sure the version is correct */
+        ver = (hdr & QCA_HDR_RECV_VERSION_MASK) >> QCA_HDR_RECV_VERSION_S;
+        if (unlikely(ver != QCA_HDR_VERSION))
+                goto out_drop;
+
+        /* Remove QCA tag and recalculate checksum */
+        skb_pull_rcsum(skb, QCA_HDR_LEN);
+        memmove(skb->data - ETH_HLEN, skb->data - ETH_HLEN - QCA_HDR_LEN,
+                ETH_HLEN - QCA_HDR_LEN);
+
+        /* This protocol doesn't support cascading multiple switches so it's
+         * safe to assume the switch is first in the tree
+         */
+        ds = dst->ds[0];
+        if (!ds)
+                goto out_drop;
+
+        /* Get source port information */
+        port = (hdr & QCA_HDR_RECV_SOURCE_PORT_MASK);
+        if (!ds->ports[port].netdev)
+                goto out_drop;
+
+        /* Update skb & forward the frame accordingly */
+        skb_push(skb, ETH_HLEN);
+        skb->pkt_type = PACKET_HOST;
+        skb->dev = ds->ports[port].netdev;
+        skb->protocol = eth_type_trans(skb, skb->dev);
+
+        skb->dev->stats.rx_packets++;
+        skb->dev->stats.rx_bytes += skb->len;
+
+        netif_receive_skb(skb);
+
+        return 0;
+
+out_drop:
+        kfree_skb(skb);
+out:
+        return 0;
+}
+
+const struct dsa_device_ops qca_netdev_ops = {
+        .xmit   = qca_tag_xmit,
+        .rcv    = qca_tag_rcv,
+};