1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2022 Schneider Electric 4 * 5 * Clément Léger <clement.leger@bootlin.com> 6 */ 7 8 #include <linux/bitfield.h> 9 #include <linux/etherdevice.h> 10 #include <linux/if_ether.h> 11 #include <net/dsa.h> 12 13 #include "tag.h" 14 15 /* To define the outgoing port and to discover the incoming port a TAG is 16 * inserted after Src MAC : 17 * 18 * Dest MAC Src MAC TAG Type 19 * ...| 1 2 3 4 5 6 | 1 2 3 4 5 6 | 1 2 3 4 5 6 7 8 | 1 2 |... 20 * |<--------------->| 21 * 22 * See struct a5psw_tag for layout 23 */ 24 25 #define A5PSW_NAME "a5psw" 26 27 #define ETH_P_DSA_A5PSW 0xE001 28 #define A5PSW_TAG_LEN 8 29 #define A5PSW_CTRL_DATA_FORCE_FORWARD BIT(0) 30 /* This is both used for xmit tag and rcv tagging */ 31 #define A5PSW_CTRL_DATA_PORT GENMASK(3, 0) 32 33 struct a5psw_tag { 34 __be16 ctrl_tag; 35 __be16 ctrl_data; 36 __be16 ctrl_data2_hi; 37 __be16 ctrl_data2_lo; 38 }; 39 40 static struct sk_buff *a5psw_tag_xmit(struct sk_buff *skb, struct net_device *dev) 41 { 42 struct dsa_port *dp = dsa_slave_to_port(dev); 43 struct a5psw_tag *ptag; 44 u32 data2_val; 45 46 BUILD_BUG_ON(sizeof(*ptag) != A5PSW_TAG_LEN); 47 48 /* The Ethernet switch we are interfaced with needs packets to be at 49 * least 60 bytes otherwise they will be discarded when they enter the 50 * switch port logic. 51 */ 52 if (__skb_put_padto(skb, ETH_ZLEN, false)) 53 return NULL; 54 55 /* provide 'A5PSW_TAG_LEN' bytes additional space */ 56 skb_push(skb, A5PSW_TAG_LEN); 57 58 /* make room between MACs and Ether-Type to insert tag */ 59 dsa_alloc_etype_header(skb, A5PSW_TAG_LEN); 60 61 ptag = dsa_etype_header_pos_tx(skb); 62 63 data2_val = FIELD_PREP(A5PSW_CTRL_DATA_PORT, BIT(dp->index)); 64 ptag->ctrl_tag = htons(ETH_P_DSA_A5PSW); 65 ptag->ctrl_data = htons(A5PSW_CTRL_DATA_FORCE_FORWARD); 66 ptag->ctrl_data2_lo = htons(data2_val); 67 ptag->ctrl_data2_hi = 0; 68 69 return skb; 70 } 71 72 static struct sk_buff *a5psw_tag_rcv(struct sk_buff *skb, 73 struct net_device *dev) 74 { 75 struct a5psw_tag *tag; 76 int port; 77 78 if (unlikely(!pskb_may_pull(skb, A5PSW_TAG_LEN))) { 79 dev_warn_ratelimited(&dev->dev, 80 "Dropping packet, cannot pull\n"); 81 return NULL; 82 } 83 84 tag = dsa_etype_header_pos_rx(skb); 85 86 if (tag->ctrl_tag != htons(ETH_P_DSA_A5PSW)) { 87 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid TAG marker\n"); 88 return NULL; 89 } 90 91 port = FIELD_GET(A5PSW_CTRL_DATA_PORT, ntohs(tag->ctrl_data)); 92 93 skb->dev = dsa_master_find_slave(dev, 0, port); 94 if (!skb->dev) 95 return NULL; 96 97 skb_pull_rcsum(skb, A5PSW_TAG_LEN); 98 dsa_strip_etype_header(skb, A5PSW_TAG_LEN); 99 100 dsa_default_offload_fwd_mark(skb); 101 102 return skb; 103 } 104 105 static const struct dsa_device_ops a5psw_netdev_ops = { 106 .name = A5PSW_NAME, 107 .proto = DSA_TAG_PROTO_RZN1_A5PSW, 108 .xmit = a5psw_tag_xmit, 109 .rcv = a5psw_tag_rcv, 110 .needed_headroom = A5PSW_TAG_LEN, 111 }; 112 113 MODULE_LICENSE("GPL v2"); 114 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_A5PSW, A5PSW_NAME); 115 module_dsa_tag_driver(a5psw_netdev_ops); 116