net: dsa: add Broadcom tag RX/TX handler
Add support for the 4-bytes Broadcom tag that built-in switches such as
the Starfighter 2 might insert when receiving packets, or that we need
to insert while targetting specific switch ports. We use a fake local
EtherType value for this 4-bytes switch tag: ETH_P_BRCMTAG to make sure
we can assign DSA-specific network operations within the DSA drivers.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dsa/tag_brcm.c b/net/dsa/tag_brcm.c
new file mode 100644
index 0000000..e0b759e
--- /dev/null
+++ b/net/dsa/tag_brcm.c
@@ -0,0 +1,173 @@
+/*
+ * Broadcom tag support
+ *
+ * Copyright (C) 2014 Broadcom Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/etherdevice.h>
+#include <linux/list.h>
+#include <linux/netdevice.h>
+#include <linux/slab.h>
+#include "dsa_priv.h"
+
+/* This tag length is 4 bytes, older ones were 6 bytes, we do not
+ * handle them
+ */
+#define BRCM_TAG_LEN 4
+
+/* Tag is constructed and desconstructed using byte by byte access
+ * because the tag is placed after the MAC Source Address, which does
+ * not make it 4-bytes aligned, so this might cause unaligned accesses
+ * on most systems where this is used.
+ */
+
+/* Ingress and egress opcodes */
+#define BRCM_OPCODE_SHIFT 5
+#define BRCM_OPCODE_MASK 0x7
+
+/* Ingress fields */
+/* 1st byte in the tag */
+#define BRCM_IG_TC_SHIFT 2
+#define BRCM_IG_TC_MASK 0x7
+/* 2nd byte in the tag */
+#define BRCM_IG_TE_MASK 0x3
+#define BRCM_IG_TS_SHIFT 7
+/* 3rd byte in the tag */
+#define BRCM_IG_DSTMAP2_MASK 1
+#define BRCM_IG_DSTMAP1_MASK 0xff
+
+/* Egress fields */
+
+/* 2nd byte in the tag */
+#define BRCM_EG_CID_MASK 0xff
+
+/* 3rd byte in the tag */
+#define BRCM_EG_RC_MASK 0xff
+#define BRCM_EG_RC_RSVD (3 << 6)
+#define BRCM_EG_RC_EXCEPTION (1 << 5)
+#define BRCM_EG_RC_PROT_SNOOP (1 << 4)
+#define BRCM_EG_RC_PROT_TERM (1 << 3)
+#define BRCM_EG_RC_SWITCH (1 << 2)
+#define BRCM_EG_RC_MAC_LEARN (1 << 1)
+#define BRCM_EG_RC_MIRROR (1 << 0)
+#define BRCM_EG_TC_SHIFT 5
+#define BRCM_EG_TC_MASK 0x7
+#define BRCM_EG_PID_MASK 0x1f
+
+static netdev_tx_t brcm_tag_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+ struct dsa_slave_priv *p = netdev_priv(dev);
+ u8 *brcm_tag;
+
+ dev->stats.tx_packets++;
+ dev->stats.tx_bytes += skb->len;
+
+ if (skb_cow_head(skb, BRCM_TAG_LEN) < 0)
+ goto out_free;
+
+ skb_push(skb, BRCM_TAG_LEN);
+
+ memmove(skb->data, skb->data + BRCM_TAG_LEN, 2 * ETH_ALEN);
+
+ /* Build the tag after the MAC Source Address */
+ brcm_tag = skb->data + 2 * ETH_ALEN;
+
+ /* Set the ingress opcode, traffic class, tag enforcment is
+ * deprecated
+ */
+ brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
+ ((skb->priority << BRCM_IG_TC_SHIFT) & BRCM_IG_TC_MASK);
+ brcm_tag[1] = 0;
+ brcm_tag[2] = 0;
+ if (p->port == 8)
+ brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
+ brcm_tag[3] = (1 << p->port) & BRCM_IG_DSTMAP1_MASK;
+
+ /* Queue the SKB for transmission on the parent interface, but
+ * do not modify its EtherType
+ */
+ skb->protocol = htons(ETH_P_BRCMTAG);
+ skb->dev = p->parent->dst->master_netdev;
+ dev_queue_xmit(skb);
+
+ return NETDEV_TX_OK;
+
+out_free:
+ kfree_skb(skb);
+ return NETDEV_TX_OK;
+}
+
+static int brcm_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;
+ int source_port;
+ u8 *brcm_tag;
+
+ if (unlikely(dst == NULL))
+ goto out_drop;
+
+ ds = dst->ds[0];
+
+ skb = skb_unshare(skb, GFP_ATOMIC);
+ if (skb == NULL)
+ goto out;
+
+ if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
+ goto out_drop;
+
+ /* skb->data points to the EtherType, the tag is right before it */
+ brcm_tag = skb->data - 2;
+
+ /* The opcode should never be different than 0b000 */
+ if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
+ goto out_drop;
+
+ /* We should never see a reserved reason code without knowing how to
+ * handle it
+ */
+ WARN_ON(brcm_tag[2] & BRCM_EG_RC_RSVD);
+
+ /* Locate which port this is coming from */
+ source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
+
+ /* Validate port against switch setup, either the port is totally */
+ if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
+ goto out_drop;
+
+ /* Remove Broadcom tag and update checksum */
+ skb_pull_rcsum(skb, BRCM_TAG_LEN);
+
+ /* Move the Ethernet DA and SA */
+ memmove(skb->data - ETH_HLEN,
+ skb->data - ETH_HLEN - BRCM_TAG_LEN,
+ 2 * ETH_ALEN);
+
+ skb_push(skb, ETH_HLEN);
+ skb->pkt_type = PACKET_HOST;
+ skb->dev = ds->ports[source_port];
+ 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 brcm_netdev_ops = {
+ .xmit = brcm_tag_xmit,
+ .rcv = brcm_tag_rcv,
+};