tag_brcm.c
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/*
* 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/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 struct sk_buff *brcm_tag_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct dsa_slave_priv *p = netdev_priv(dev);
u8 *brcm_tag;
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;
return skb;
out_free:
kfree_skb(skb);
return NULL;
}
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].netdev)
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].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 brcm_netdev_ops = {
.xmit = brcm_tag_xmit,
.rcv = brcm_tag_rcv,
};