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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_XMIT_TAGGED_TPID_88A8 2
- #define MTK_HDR_RECV_SOURCE_PORT_MASK GENMASK(2, 0)
- #define MTK_HDR_XMIT_DP_BIT_MASK GENMASK(5, 0)
- #define MTK_HDR_XMIT_SA_DIS BIT(6)
- 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 xmit_tpid;
- u8 *mtk_tag;
- unsigned char *dest = eth_hdr(skb)->h_dest;
- bool is_multicast_skb = is_multicast_ether_addr(dest) &&
- !is_broadcast_ether_addr(dest);
- /* 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.
- */
- switch (skb->protocol) {
- case htons(ETH_P_8021Q):
- xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_8100;
- break;
- case htons(ETH_P_8021AD):
- xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_88A8;
- break;
- default:
- xmit_tpid = MTK_HDR_XMIT_UNTAGGED;
- skb_push(skb, MTK_HDR_LEN);
- memmove(skb->data, skb->data + MTK_HDR_LEN, 2 * ETH_ALEN);
- }
- 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] = xmit_tpid;
- mtk_tag[1] = (1 << dp->index) & MTK_HDR_XMIT_DP_BIT_MASK;
- /* Disable SA learning for multicast frames */
- if (unlikely(is_multicast_skb))
- mtk_tag[1] |= MTK_HDR_XMIT_SA_DIS;
- /* Tag control information is kept for 802.1Q */
- if (xmit_tpid == MTK_HDR_XMIT_UNTAGGED) {
- 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)
- {
- u16 hdr;
- int port;
- __be16 *phdr;
- unsigned char *dest = eth_hdr(skb)->h_dest;
- bool is_multicast_skb = is_multicast_ether_addr(dest) &&
- !is_broadcast_ether_addr(dest);
- 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;
- /* Only unicast or broadcast frames are offloaded */
- if (likely(!is_multicast_skb))
- skb->offload_fwd_mark = 1;
- return skb;
- }
- static const struct dsa_device_ops mtk_netdev_ops = {
- .name = "mtk",
- .proto = DSA_TAG_PROTO_MTK,
- .xmit = mtk_tag_xmit,
- .rcv = mtk_tag_rcv,
- .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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