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4e50025129
Some really really weird switches just couldn't decide whether to use a normal or a tail tagger, so they just did both. This creates problems for DSA, because we only have the concept of an 'overhead' which can be applied to the headroom or to the tailroom of the skb (like for example during the central TX reallocation procedure), depending on the value of bool tail_tag, but not to both. We need to generalize DSA to cater for these odd switches by transforming the 'overhead / tail_tag' pair into 'needed_headroom / needed_tailroom'. The DSA master's MTU is increased to account for both. The flow dissector code is modified such that it only calls the DSA adjustment callback if the tagger has a non-zero header length. Taggers are trivially modified to declare either needed_headroom or needed_tailroom, based on the tail_tag value that they currently declare. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
111 lines
2.8 KiB
C
111 lines
2.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Mediatek DSA Tag support
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* Copyright (C) 2017 Landen Chao <landen.chao@mediatek.com>
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* Sean Wang <sean.wang@mediatek.com>
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*/
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#include <linux/etherdevice.h>
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#include <linux/if_vlan.h>
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#include "dsa_priv.h"
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#define MTK_HDR_LEN 4
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#define MTK_HDR_XMIT_UNTAGGED 0
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#define MTK_HDR_XMIT_TAGGED_TPID_8100 1
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#define MTK_HDR_XMIT_TAGGED_TPID_88A8 2
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#define MTK_HDR_RECV_SOURCE_PORT_MASK GENMASK(2, 0)
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#define MTK_HDR_XMIT_DP_BIT_MASK GENMASK(5, 0)
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#define MTK_HDR_XMIT_SA_DIS BIT(6)
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static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
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struct net_device *dev)
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{
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struct dsa_port *dp = dsa_slave_to_port(dev);
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u8 xmit_tpid;
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u8 *mtk_tag;
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/* Build the special tag after the MAC Source Address. If VLAN header
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* is present, it's required that VLAN header and special tag is
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* being combined. Only in this way we can allow the switch can parse
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* the both special and VLAN tag at the same time and then look up VLAN
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* table with VID.
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*/
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switch (skb->protocol) {
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case htons(ETH_P_8021Q):
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xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_8100;
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break;
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case htons(ETH_P_8021AD):
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xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_88A8;
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break;
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default:
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xmit_tpid = MTK_HDR_XMIT_UNTAGGED;
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skb_push(skb, MTK_HDR_LEN);
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memmove(skb->data, skb->data + MTK_HDR_LEN, 2 * ETH_ALEN);
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}
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mtk_tag = skb->data + 2 * ETH_ALEN;
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/* Mark tag attribute on special tag insertion to notify hardware
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* whether that's a combined special tag with 802.1Q header.
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*/
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mtk_tag[0] = xmit_tpid;
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mtk_tag[1] = (1 << dp->index) & MTK_HDR_XMIT_DP_BIT_MASK;
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/* Tag control information is kept for 802.1Q */
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if (xmit_tpid == MTK_HDR_XMIT_UNTAGGED) {
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mtk_tag[2] = 0;
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mtk_tag[3] = 0;
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}
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return skb;
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}
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static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
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struct packet_type *pt)
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{
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u16 hdr;
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int port;
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__be16 *phdr;
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if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
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return NULL;
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/* The MTK header is added by the switch between src addr
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* and ethertype at this point, skb->data points to 2 bytes
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* after src addr so header should be 2 bytes right before.
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*/
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phdr = (__be16 *)(skb->data - 2);
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hdr = ntohs(*phdr);
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/* Remove MTK tag and recalculate checksum. */
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skb_pull_rcsum(skb, MTK_HDR_LEN);
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memmove(skb->data - ETH_HLEN,
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skb->data - ETH_HLEN - MTK_HDR_LEN,
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2 * ETH_ALEN);
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/* Get source port information */
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port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
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skb->dev = dsa_master_find_slave(dev, 0, port);
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if (!skb->dev)
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return NULL;
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skb->offload_fwd_mark = 1;
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return skb;
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}
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static const struct dsa_device_ops mtk_netdev_ops = {
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.name = "mtk",
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.proto = DSA_TAG_PROTO_MTK,
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.xmit = mtk_tag_xmit,
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.rcv = mtk_tag_rcv,
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.needed_headroom = MTK_HDR_LEN,
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};
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK);
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module_dsa_tag_driver(mtk_netdev_ops);
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