// 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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unsigned char *dest = eth_hdr(skb)->h_dest;
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bool is_multicast_skb = is_multicast_ether_addr(dest) &&
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!is_broadcast_ether_addr(dest);
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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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/* Disable SA learning for multicast frames */
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if (unlikely(is_multicast_skb))
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mtk_tag[1] |= MTK_HDR_XMIT_SA_DIS;
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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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unsigned char *dest = eth_hdr(skb)->h_dest;
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bool is_multicast_skb = is_multicast_ether_addr(dest) &&
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!is_broadcast_ether_addr(dest);
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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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/* Only unicast or broadcast frames are offloaded */
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if (likely(!is_multicast_skb))
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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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.overhead = 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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