tag_mtk.c 3.3 KB

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  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. #include <linux/etherdevice.h>
  8. #include <linux/if_vlan.h>
  9. #include "dsa_priv.h"
  10. #define MTK_HDR_LEN 4
  11. #define MTK_HDR_XMIT_UNTAGGED 0
  12. #define MTK_HDR_XMIT_TAGGED_TPID_8100 1
  13. #define MTK_HDR_XMIT_TAGGED_TPID_88A8 2
  14. #define MTK_HDR_RECV_SOURCE_PORT_MASK GENMASK(2, 0)
  15. #define MTK_HDR_XMIT_DP_BIT_MASK GENMASK(5, 0)
  16. #define MTK_HDR_XMIT_SA_DIS BIT(6)
  17. static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
  18. struct net_device *dev)
  19. {
  20. struct dsa_port *dp = dsa_slave_to_port(dev);
  21. u8 xmit_tpid;
  22. u8 *mtk_tag;
  23. unsigned char *dest = eth_hdr(skb)->h_dest;
  24. bool is_multicast_skb = is_multicast_ether_addr(dest) &&
  25. !is_broadcast_ether_addr(dest);
  26. /* Build the special tag after the MAC Source Address. If VLAN header
  27. * is present, it's required that VLAN header and special tag is
  28. * being combined. Only in this way we can allow the switch can parse
  29. * the both special and VLAN tag at the same time and then look up VLAN
  30. * table with VID.
  31. */
  32. switch (skb->protocol) {
  33. case htons(ETH_P_8021Q):
  34. xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_8100;
  35. break;
  36. case htons(ETH_P_8021AD):
  37. xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_88A8;
  38. break;
  39. default:
  40. xmit_tpid = MTK_HDR_XMIT_UNTAGGED;
  41. skb_push(skb, MTK_HDR_LEN);
  42. memmove(skb->data, skb->data + MTK_HDR_LEN, 2 * ETH_ALEN);
  43. }
  44. mtk_tag = skb->data + 2 * ETH_ALEN;
  45. /* Mark tag attribute on special tag insertion to notify hardware
  46. * whether that's a combined special tag with 802.1Q header.
  47. */
  48. mtk_tag[0] = xmit_tpid;
  49. mtk_tag[1] = (1 << dp->index) & MTK_HDR_XMIT_DP_BIT_MASK;
  50. /* Disable SA learning for multicast frames */
  51. if (unlikely(is_multicast_skb))
  52. mtk_tag[1] |= MTK_HDR_XMIT_SA_DIS;
  53. /* Tag control information is kept for 802.1Q */
  54. if (xmit_tpid == MTK_HDR_XMIT_UNTAGGED) {
  55. mtk_tag[2] = 0;
  56. mtk_tag[3] = 0;
  57. }
  58. return skb;
  59. }
  60. static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
  61. struct packet_type *pt)
  62. {
  63. u16 hdr;
  64. int port;
  65. __be16 *phdr;
  66. unsigned char *dest = eth_hdr(skb)->h_dest;
  67. bool is_multicast_skb = is_multicast_ether_addr(dest) &&
  68. !is_broadcast_ether_addr(dest);
  69. if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
  70. return NULL;
  71. /* The MTK header is added by the switch between src addr
  72. * and ethertype at this point, skb->data points to 2 bytes
  73. * after src addr so header should be 2 bytes right before.
  74. */
  75. phdr = (__be16 *)(skb->data - 2);
  76. hdr = ntohs(*phdr);
  77. /* Remove MTK tag and recalculate checksum. */
  78. skb_pull_rcsum(skb, MTK_HDR_LEN);
  79. memmove(skb->data - ETH_HLEN,
  80. skb->data - ETH_HLEN - MTK_HDR_LEN,
  81. 2 * ETH_ALEN);
  82. /* Get source port information */
  83. port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
  84. skb->dev = dsa_master_find_slave(dev, 0, port);
  85. if (!skb->dev)
  86. return NULL;
  87. /* Only unicast or broadcast frames are offloaded */
  88. if (likely(!is_multicast_skb))
  89. skb->offload_fwd_mark = 1;
  90. return skb;
  91. }
  92. static const struct dsa_device_ops mtk_netdev_ops = {
  93. .name = "mtk",
  94. .proto = DSA_TAG_PROTO_MTK,
  95. .xmit = mtk_tag_xmit,
  96. .rcv = mtk_tag_rcv,
  97. .overhead = MTK_HDR_LEN,
  98. };
  99. MODULE_LICENSE("GPL");
  100. MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK);
  101. module_dsa_tag_driver(mtk_netdev_ops);