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ffainellidavem330
ffainelli
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davem330
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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 <[email protected]> Signed-off-by: David S. Miller <[email protected]>
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‎include/net/dsa.h‎

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@@ -19,6 +19,11 @@
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#include <linux/phy.h>
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#include <linux/phy_fixed.h>
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/* Not an official ethertype value, used only internally for DSA
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* demultiplexing
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*/
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#define ETH_P_BRCMTAG (ETH_P_XDSA + 1)
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#define DSA_MAX_SWITCHES 4
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#define DSA_MAX_PORTS 12
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‎net/dsa/Kconfig‎

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@@ -12,6 +12,9 @@ config NET_DSA
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if NET_DSA
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# tagging formats
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config NET_DSA_TAG_BRCM
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bool
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config NET_DSA_TAG_DSA
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bool
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‎net/dsa/Makefile‎

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@@ -3,6 +3,7 @@ obj-$(CONFIG_NET_DSA) += dsa_core.o
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dsa_core-y += dsa.o slave.o
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# tagging formats
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dsa_core-$(CONFIG_NET_DSA_TAG_BRCM) += tag_brcm.o
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dsa_core-$(CONFIG_NET_DSA_TAG_DSA) += tag_dsa.o
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dsa_core-$(CONFIG_NET_DSA_TAG_EDSA) += tag_edsa.o
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dsa_core-$(CONFIG_NET_DSA_TAG_TRAILER) += tag_trailer.o

‎net/dsa/dsa_priv.h‎

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@@ -57,5 +57,8 @@ extern const struct dsa_device_ops edsa_netdev_ops;
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/* tag_trailer.c */
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extern const struct dsa_device_ops trailer_netdev_ops;
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/* tag_brcm.c */
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extern const struct dsa_device_ops brcm_netdev_ops;
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#endif

‎net/dsa/slave.c‎

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@@ -450,6 +450,11 @@ dsa_slave_create(struct dsa_switch *ds, struct device *parent,
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case htons(ETH_P_TRAILER):
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ds->dst->ops = &trailer_netdev_ops;
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break;
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#endif
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#ifdef CONFIG_NET_DSA_TAG_BRCM
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case htons(ETH_P_BRCMTAG):
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ds->dst->ops = &brcm_netdev_ops;
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break;
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#endif
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default:
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ds->dst->ops = &notag_netdev_ops;

‎net/dsa/tag_brcm.c‎

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@@ -0,0 +1,173 @@
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/*
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* Broadcom tag support
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*
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* Copyright (C) 2014 Broadcom Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/etherdevice.h>
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#include <linux/list.h>
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#include <linux/netdevice.h>
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#include <linux/slab.h>
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#include "dsa_priv.h"
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/* This tag length is 4 bytes, older ones were 6 bytes, we do not
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* handle them
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*/
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#define BRCM_TAG_LEN 4
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/* Tag is constructed and desconstructed using byte by byte access
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* because the tag is placed after the MAC Source Address, which does
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* not make it 4-bytes aligned, so this might cause unaligned accesses
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* on most systems where this is used.
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*/
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/* Ingress and egress opcodes */
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#define BRCM_OPCODE_SHIFT 5
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#define BRCM_OPCODE_MASK 0x7
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/* Ingress fields */
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/* 1st byte in the tag */
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#define BRCM_IG_TC_SHIFT 2
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#define BRCM_IG_TC_MASK 0x7
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/* 2nd byte in the tag */
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#define BRCM_IG_TE_MASK 0x3
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#define BRCM_IG_TS_SHIFT 7
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/* 3rd byte in the tag */
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#define BRCM_IG_DSTMAP2_MASK 1
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#define BRCM_IG_DSTMAP1_MASK 0xff
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/* Egress fields */
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/* 2nd byte in the tag */
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#define BRCM_EG_CID_MASK 0xff
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/* 3rd byte in the tag */
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#define BRCM_EG_RC_MASK 0xff
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#define BRCM_EG_RC_RSVD (3 << 6)
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#define BRCM_EG_RC_EXCEPTION (1 << 5)
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#define BRCM_EG_RC_PROT_SNOOP (1 << 4)
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#define BRCM_EG_RC_PROT_TERM (1 << 3)
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#define BRCM_EG_RC_SWITCH (1 << 2)
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#define BRCM_EG_RC_MAC_LEARN (1 << 1)
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#define BRCM_EG_RC_MIRROR (1 << 0)
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#define BRCM_EG_TC_SHIFT 5
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#define BRCM_EG_TC_MASK 0x7
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#define BRCM_EG_PID_MASK 0x1f
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static netdev_tx_t brcm_tag_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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struct dsa_slave_priv *p = netdev_priv(dev);
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u8 *brcm_tag;
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dev->stats.tx_packets++;
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dev->stats.tx_bytes += skb->len;
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if (skb_cow_head(skb, BRCM_TAG_LEN) < 0)
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goto out_free;
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skb_push(skb, BRCM_TAG_LEN);
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memmove(skb->data, skb->data + BRCM_TAG_LEN, 2 * ETH_ALEN);
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/* Build the tag after the MAC Source Address */
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brcm_tag = skb->data + 2 * ETH_ALEN;
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/* Set the ingress opcode, traffic class, tag enforcment is
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* deprecated
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*/
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brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
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((skb->priority << BRCM_IG_TC_SHIFT) & BRCM_IG_TC_MASK);
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brcm_tag[1] = 0;
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brcm_tag[2] = 0;
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if (p->port == 8)
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brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
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brcm_tag[3] = (1 << p->port) & BRCM_IG_DSTMAP1_MASK;
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/* Queue the SKB for transmission on the parent interface, but
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* do not modify its EtherType
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*/
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skb->protocol = htons(ETH_P_BRCMTAG);
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skb->dev = p->parent->dst->master_netdev;
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dev_queue_xmit(skb);
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return NETDEV_TX_OK;
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out_free:
101+
kfree_skb(skb);
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return NETDEV_TX_OK;
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}
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static int brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
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struct packet_type *pt, struct net_device *orig_dev)
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{
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struct dsa_switch_tree *dst = dev->dsa_ptr;
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struct dsa_switch *ds;
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int source_port;
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u8 *brcm_tag;
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if (unlikely(dst == NULL))
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goto out_drop;
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ds = dst->ds[0];
117+
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skb = skb_unshare(skb, GFP_ATOMIC);
119+
if (skb == NULL)
120+
goto out;
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122+
if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
123+
goto out_drop;
124+
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/* skb->data points to the EtherType, the tag is right before it */
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brcm_tag = skb->data - 2;
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/* The opcode should never be different than 0b000 */
129+
if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
130+
goto out_drop;
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/* We should never see a reserved reason code without knowing how to
133+
* handle it
134+
*/
135+
WARN_ON(brcm_tag[2] & BRCM_EG_RC_RSVD);
136+
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/* Locate which port this is coming from */
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source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
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/* Validate port against switch setup, either the port is totally */
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if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
142+
goto out_drop;
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/* Remove Broadcom tag and update checksum */
145+
skb_pull_rcsum(skb, BRCM_TAG_LEN);
146+
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/* Move the Ethernet DA and SA */
148+
memmove(skb->data - ETH_HLEN,
149+
skb->data - ETH_HLEN - BRCM_TAG_LEN,
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2 * ETH_ALEN);
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skb_push(skb, ETH_HLEN);
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skb->pkt_type = PACKET_HOST;
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skb->dev = ds->ports[source_port];
155+
skb->protocol = eth_type_trans(skb, skb->dev);
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157+
skb->dev->stats.rx_packets++;
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skb->dev->stats.rx_bytes += skb->len;
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netif_receive_skb(skb);
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162+
return 0;
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out_drop:
165+
kfree_skb(skb);
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out:
167+
return 0;
168+
}
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const struct dsa_device_ops brcm_netdev_ops = {
171+
.xmit = brcm_tag_xmit,
172+
.rcv = brcm_tag_rcv,
173+
};

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