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 "dsa_priv.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 ETH_P_DSA_A5PSW 0xE001 26 #define A5PSW_TAG_LEN 8 27 #define A5PSW_CTRL_DATA_FORCE_FORWARD BIT(0) 28 /* This is both used for xmit tag and rcv tagging */ 29 #define A5PSW_CTRL_DATA_PORT GENMASK(3, 0) 30 31 struct a5psw_tag { 32 __be16 ctrl_tag; 33 __be16 ctrl_data; 34 __be16 ctrl_data2_hi; 35 __be16 ctrl_data2_lo; 36 }; 37 38 static struct sk_buff *a5psw_tag_xmit(struct sk_buff *skb, struct net_device *dev) 39 { 40 struct dsa_port *dp = dsa_slave_to_port(dev); 41 struct a5psw_tag *ptag; 42 u32 data2_val; 43 44 BUILD_BUG_ON(sizeof(*ptag) != A5PSW_TAG_LEN); 45 46 /* The Ethernet switch we are interfaced with needs packets to be at 47 * least 60 bytes otherwise they will be discarded when they enter the 48 * switch port logic. 49 */ 50 if (__skb_put_padto(skb, ETH_ZLEN, false)) 51 return NULL; 52 53 /* provide 'A5PSW_TAG_LEN' bytes additional space */ 54 skb_push(skb, A5PSW_TAG_LEN); 55 56 /* make room between MACs and Ether-Type to insert tag */ 57 dsa_alloc_etype_header(skb, A5PSW_TAG_LEN); 58 59 ptag = dsa_etype_header_pos_tx(skb); 60 61 data2_val = FIELD_PREP(A5PSW_CTRL_DATA_PORT, BIT(dp->index)); 62 ptag->ctrl_tag = htons(ETH_P_DSA_A5PSW); 63 ptag->ctrl_data = htons(A5PSW_CTRL_DATA_FORCE_FORWARD); 64 ptag->ctrl_data2_lo = htons(data2_val); 65 ptag->ctrl_data2_hi = 0; 66 67 return skb; 68 } 69 70 static struct sk_buff *a5psw_tag_rcv(struct sk_buff *skb, 71 struct net_device *dev) 72 { 73 struct a5psw_tag *tag; 74 int port; 75 76 if (unlikely(!pskb_may_pull(skb, A5PSW_TAG_LEN))) { 77 dev_warn_ratelimited(&dev->dev, 78 "Dropping packet, cannot pull\n"); 79 return NULL; 80 } 81 82 tag = dsa_etype_header_pos_rx(skb); 83 84 if (tag->ctrl_tag != htons(ETH_P_DSA_A5PSW)) { 85 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid TAG marker\n"); 86 return NULL; 87 } 88 89 port = FIELD_GET(A5PSW_CTRL_DATA_PORT, ntohs(tag->ctrl_data)); 90 91 skb->dev = dsa_master_find_slave(dev, 0, port); 92 if (!skb->dev) 93 return NULL; 94 95 skb_pull_rcsum(skb, A5PSW_TAG_LEN); 96 dsa_strip_etype_header(skb, A5PSW_TAG_LEN); 97 98 dsa_default_offload_fwd_mark(skb); 99 100 return skb; 101 } 102 103 static const struct dsa_device_ops a5psw_netdev_ops = { 104 .name = "a5psw", 105 .proto = DSA_TAG_PROTO_RZN1_A5PSW, 106 .xmit = a5psw_tag_xmit, 107 .rcv = a5psw_tag_rcv, 108 .needed_headroom = A5PSW_TAG_LEN, 109 }; 110 111 MODULE_LICENSE("GPL v2"); 112 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_A5PSW); 113 module_dsa_tag_driver(a5psw_netdev_ops); 114