tag_mtk.c

  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] = FIELD_PREP(MTK_HDR_XMIT_DP_BIT_MASK,
 58				dsa_xmit_port_mask(skb, dev));
 59
 60	/* Tag control information is kept for 802.1Q */
 61	if (xmit_tpid == MTK_HDR_XMIT_UNTAGGED) {
 62		mtk_tag[2] = 0;
 63		mtk_tag[3] = 0;
 64	}
 65
 66	return skb;
 67}
 68
 69static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev)
 70{
 71	u16 hdr;
 72	int port;
 73	__be16 *phdr;
 74
 75	if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
 76		return NULL;
 77
 78	phdr = dsa_etype_header_pos_rx(skb);
 79	hdr = ntohs(*phdr);
 80
 81	/* Remove MTK tag and recalculate checksum. */
 82	skb_pull_rcsum(skb, MTK_HDR_LEN);
 83
 84	dsa_strip_etype_header(skb, MTK_HDR_LEN);
 85
 86	/* Get source port information */
 87	port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
 88
 89	skb->dev = dsa_conduit_find_user(dev, 0, port);
 90	if (!skb->dev)
 91		return NULL;
 92
 93	dsa_default_offload_fwd_mark(skb);
 94
 95	return skb;
 96}
 97
 98static const struct dsa_device_ops mtk_netdev_ops = {
 99	.name		= MTK_NAME,
100	.proto		= DSA_TAG_PROTO_MTK,
101	.xmit		= mtk_tag_xmit,
102	.rcv		= mtk_tag_rcv,
103	.needed_headroom = MTK_HDR_LEN,
104};
105
106MODULE_DESCRIPTION("DSA tag driver for Mediatek switches");
107MODULE_LICENSE("GPL");
108MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK, MTK_NAME);
109
110module_dsa_tag_driver(mtk_netdev_ops);