net/dsa/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
  23 static 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
  68 static 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
  97 static 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
 105 MODULE_DESCRIPTION("DSA tag driver for Mediatek switches");
 106 MODULE_LICENSE("GPL");
 107 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK, MTK_NAME);
 108
 109 module_dsa_tag_driver(mtk_netdev_ops);