1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Mediatek DSA Tag support
  4 * Copyright (C) 2017 Landen Chao <landen.chao@mediatek.com>
  5 *		      Sean Wang <sean.wang@mediatek.com>
  6 */
  7
  8#include <linux/etherdevice.h>
  9#include <linux/if_vlan.h>
 10
 11#include "tag.h"
 12
 13#define MTK_NAME		"mtk"
 14
 15#define MTK_HDR_LEN		4
 16#define MTK_HDR_XMIT_UNTAGGED		0
 17#define MTK_HDR_XMIT_TAGGED_TPID_8100	1
 18#define MTK_HDR_XMIT_TAGGED_TPID_88A8	2
 19#define MTK_HDR_RECV_SOURCE_PORT_MASK	GENMASK(2, 0)
 20#define MTK_HDR_XMIT_DP_BIT_MASK	GENMASK(5, 0)
 21#define MTK_HDR_XMIT_SA_DIS		BIT(6)
 22
 23static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
 24				    struct net_device *dev)
 25{
 26	struct dsa_port *dp = dsa_user_to_port(dev);
 27	u8 xmit_tpid;
 28	u8 *mtk_tag;
 29
 30	skb_set_queue_mapping(skb, dp->index);
 31
 32	/* Build the special tag after the MAC Source Address. If VLAN header
 33	 * is present, it's required that VLAN header and special tag is
 34	 * being combined. Only in this way we can allow the switch can parse
 35	 * the both special and VLAN tag at the same time and then look up VLAN
 36	 * table with VID.
 37	 */
 38	switch (skb->protocol) {
 39	case htons(ETH_P_8021Q):
 40		xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_8100;
 41		break;
 42	case htons(ETH_P_8021AD):
 43		xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_88A8;
 44		break;
 45	default:
 46		xmit_tpid = MTK_HDR_XMIT_UNTAGGED;
 47		skb_push(skb, MTK_HDR_LEN);
 48		dsa_alloc_etype_header(skb, MTK_HDR_LEN);
 49	}
 50
 51	mtk_tag = dsa_etype_header_pos_tx(skb);
 52
 53	/* Mark tag attribute on special tag insertion to notify hardware
 54	 * whether that's a combined special tag with 802.1Q header.
 55	 */
 56	mtk_tag[0] = xmit_tpid;
 57	mtk_tag[1] = (1 << dp->index) & MTK_HDR_XMIT_DP_BIT_MASK;
 58
 59	/* Tag control information is kept for 802.1Q */
 60	if (xmit_tpid == MTK_HDR_XMIT_UNTAGGED) {
 61		mtk_tag[2] = 0;
 62		mtk_tag[3] = 0;
 63	}
 64
 65	return skb;
 66}
 67
 68static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev)
 69{
 70	u16 hdr;
 71	int port;
 72	__be16 *phdr;
 73
 74	if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
 75		return NULL;
 76
 77	phdr = dsa_etype_header_pos_rx(skb);
 78	hdr = ntohs(*phdr);
 79
 80	/* Remove MTK tag and recalculate checksum. */
 81	skb_pull_rcsum(skb, MTK_HDR_LEN);
 82
 83	dsa_strip_etype_header(skb, MTK_HDR_LEN);
 84
 85	/* Get source port information */
 86	port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
 87
 88	skb->dev = dsa_conduit_find_user(dev, 0, port);
 89	if (!skb->dev)
 90		return NULL;
 91
 92	dsa_default_offload_fwd_mark(skb);
 93
 94	return skb;
 95}
 96
 97static const struct dsa_device_ops mtk_netdev_ops = {
 98	.name		= MTK_NAME,
 99	.proto		= DSA_TAG_PROTO_MTK,
100	.xmit		= mtk_tag_xmit,
101	.rcv		= mtk_tag_rcv,
102	.needed_headroom = MTK_HDR_LEN,
103};
104
105MODULE_DESCRIPTION("DSA tag driver for Mediatek switches");
106MODULE_LICENSE("GPL");
107MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK, MTK_NAME);
108
109module_dsa_tag_driver(mtk_netdev_ops);