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// SPDX-License-Identifier: GPL-2.0
/*
* Mediatek DSA Tag support
* Copyright (C) 2017 Landen Chao <landen.chao@mediatek.com>
* Sean Wang <sean.wang@mediatek.com>
*/
#include <linux/etherdevice.h>
#include <linux/if_vlan.h>
#include "dsa_priv.h"
#define MTK_HDR_LEN 4
#define MTK_HDR_XMIT_UNTAGGED 0
#define MTK_HDR_XMIT_TAGGED_TPID_8100 1
#define MTK_HDR_RECV_SOURCE_PORT_MASK GENMASK(2, 0)
#define MTK_HDR_XMIT_DP_BIT_MASK GENMASK(5, 0)
static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
struct net_device *dev)
{
struct dsa_port *dp = dsa_slave_to_port(dev);
u8 *mtk_tag;
bool is_vlan_skb = true;
/* Build the special tag after the MAC Source Address. If VLAN header
* is present, it's required that VLAN header and special tag is
* being combined. Only in this way we can allow the switch can parse
* the both special and VLAN tag at the same time and then look up VLAN
* table with VID.
*/
if (!skb_vlan_tagged(skb)) {
if (skb_cow_head(skb, MTK_HDR_LEN) < 0)
return NULL;
skb_push(skb, MTK_HDR_LEN);
memmove(skb->data, skb->data + MTK_HDR_LEN, 2 * ETH_ALEN);
is_vlan_skb = false;
}
mtk_tag = skb->data + 2 * ETH_ALEN;
/* Mark tag attribute on special tag insertion to notify hardware
* whether that's a combined special tag with 802.1Q header.
*/
mtk_tag[0] = is_vlan_skb ? MTK_HDR_XMIT_TAGGED_TPID_8100 :
MTK_HDR_XMIT_UNTAGGED;
mtk_tag[1] = (1 << dp->index) & MTK_HDR_XMIT_DP_BIT_MASK;
/* Tag control information is kept for 802.1Q */
if (!is_vlan_skb) {
mtk_tag[2] = 0;
mtk_tag[3] = 0;
}
return skb;
}
static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt)
{
int port;
__be16 *phdr, hdr;
if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
return NULL;
/* The MTK header is added by the switch between src addr
* and ethertype at this point, skb->data points to 2 bytes
* after src addr so header should be 2 bytes right before.
*/
phdr = (__be16 *)(skb->data - 2);
hdr = ntohs(*phdr);
/* Remove MTK tag and recalculate checksum. */
skb_pull_rcsum(skb, MTK_HDR_LEN);
memmove(skb->data - ETH_HLEN,
skb->data - ETH_HLEN - MTK_HDR_LEN,
2 * ETH_ALEN);
/* Get source port information */
port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
skb->dev = dsa_master_find_slave(dev, 0, port);
if (!skb->dev)
return NULL;
return skb;
}
static int mtk_tag_flow_dissect(const struct sk_buff *skb, __be16 *proto,
int *offset)
{
*offset = 4;
*proto = ((__be16 *)skb->data)[1];
return 0;
}
static const struct dsa_device_ops mtk_netdev_ops = {
.name = "mtk",
.proto = DSA_TAG_PROTO_MTK,
.xmit = mtk_tag_xmit,
.rcv = mtk_tag_rcv,
.flow_dissect = mtk_tag_flow_dissect,
.overhead = MTK_HDR_LEN,
};
MODULE_LICENSE("GPL");
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK);
module_dsa_tag_driver(mtk_netdev_ops);
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