1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Broadcom tag support 4 * 5 * Copyright (C) 2014 Broadcom Corporation 6 */ 7 8 #include <linux/etherdevice.h> 9 #include <linux/list.h> 10 #include <linux/slab.h> 11 12 #include "dsa_priv.h" 13 14 /* This tag length is 4 bytes, older ones were 6 bytes, we do not 15 * handle them 16 */ 17 #define BRCM_TAG_LEN 4 18 19 /* Tag is constructed and desconstructed using byte by byte access 20 * because the tag is placed after the MAC Source Address, which does 21 * not make it 4-bytes aligned, so this might cause unaligned accesses 22 * on most systems where this is used. 23 */ 24 25 /* Ingress and egress opcodes */ 26 #define BRCM_OPCODE_SHIFT 5 27 #define BRCM_OPCODE_MASK 0x7 28 29 /* Ingress fields */ 30 /* 1st byte in the tag */ 31 #define BRCM_IG_TC_SHIFT 2 32 #define BRCM_IG_TC_MASK 0x7 33 /* 2nd byte in the tag */ 34 #define BRCM_IG_TE_MASK 0x3 35 #define BRCM_IG_TS_SHIFT 7 36 /* 3rd byte in the tag */ 37 #define BRCM_IG_DSTMAP2_MASK 1 38 #define BRCM_IG_DSTMAP1_MASK 0xff 39 40 /* Egress fields */ 41 42 /* 2nd byte in the tag */ 43 #define BRCM_EG_CID_MASK 0xff 44 45 /* 3rd byte in the tag */ 46 #define BRCM_EG_RC_MASK 0xff 47 #define BRCM_EG_RC_RSVD (3 << 6) 48 #define BRCM_EG_RC_EXCEPTION (1 << 5) 49 #define BRCM_EG_RC_PROT_SNOOP (1 << 4) 50 #define BRCM_EG_RC_PROT_TERM (1 << 3) 51 #define BRCM_EG_RC_SWITCH (1 << 2) 52 #define BRCM_EG_RC_MAC_LEARN (1 << 1) 53 #define BRCM_EG_RC_MIRROR (1 << 0) 54 #define BRCM_EG_TC_SHIFT 5 55 #define BRCM_EG_TC_MASK 0x7 56 #define BRCM_EG_PID_MASK 0x1f 57 58 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM) || \ 59 IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND) 60 61 static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb, 62 struct net_device *dev, 63 unsigned int offset) 64 { 65 struct dsa_port *dp = dsa_slave_to_port(dev); 66 u16 queue = skb_get_queue_mapping(skb); 67 u8 *brcm_tag; 68 69 /* The Ethernet switch we are interfaced with needs packets to be at 70 * least 64 bytes (including FCS) otherwise they will be discarded when 71 * they enter the switch port logic. When Broadcom tags are enabled, we 72 * need to make sure that packets are at least 68 bytes 73 * (including FCS and tag) because the length verification is done after 74 * the Broadcom tag is stripped off the ingress packet. 75 * 76 * Let dsa_slave_xmit() free the SKB 77 */ 78 if (__skb_put_padto(skb, ETH_ZLEN + BRCM_TAG_LEN, false)) 79 return NULL; 80 81 skb_push(skb, BRCM_TAG_LEN); 82 83 if (offset) 84 memmove(skb->data, skb->data + BRCM_TAG_LEN, offset); 85 86 brcm_tag = skb->data + offset; 87 88 /* Set the ingress opcode, traffic class, tag enforcment is 89 * deprecated 90 */ 91 brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) | 92 ((queue & BRCM_IG_TC_MASK) << BRCM_IG_TC_SHIFT); 93 brcm_tag[1] = 0; 94 brcm_tag[2] = 0; 95 if (dp->index == 8) 96 brcm_tag[2] = BRCM_IG_DSTMAP2_MASK; 97 brcm_tag[3] = (1 << dp->index) & BRCM_IG_DSTMAP1_MASK; 98 99 /* Now tell the master network device about the desired output queue 100 * as well 101 */ 102 skb_set_queue_mapping(skb, BRCM_TAG_SET_PORT_QUEUE(dp->index, queue)); 103 104 return skb; 105 } 106 107 /* Frames with this tag have one of these two layouts: 108 * ----------------------------------- 109 * | MAC DA | MAC SA | 4b tag | Type | DSA_TAG_PROTO_BRCM 110 * ----------------------------------- 111 * ----------------------------------- 112 * | 4b tag | MAC DA | MAC SA | Type | DSA_TAG_PROTO_BRCM_PREPEND 113 * ----------------------------------- 114 * In both cases, at receive time, skb->data points 2 bytes before the actual 115 * Ethernet type field and we have an offset of 4bytes between where skb->data 116 * and where the payload starts. So the same low-level receive function can be 117 * used. 118 */ 119 static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb, 120 struct net_device *dev, 121 struct packet_type *pt, 122 unsigned int offset) 123 { 124 int source_port; 125 u8 *brcm_tag; 126 127 if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN))) 128 return NULL; 129 130 brcm_tag = skb->data - offset; 131 132 /* The opcode should never be different than 0b000 */ 133 if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK)) 134 return NULL; 135 136 /* We should never see a reserved reason code without knowing how to 137 * handle it 138 */ 139 if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD)) 140 return NULL; 141 142 /* Locate which port this is coming from */ 143 source_port = brcm_tag[3] & BRCM_EG_PID_MASK; 144 145 skb->dev = dsa_master_find_slave(dev, 0, source_port); 146 if (!skb->dev) 147 return NULL; 148 149 /* Remove Broadcom tag and update checksum */ 150 skb_pull_rcsum(skb, BRCM_TAG_LEN); 151 152 skb->offload_fwd_mark = 1; 153 154 return skb; 155 } 156 #endif 157 158 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM) 159 static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb, 160 struct net_device *dev) 161 { 162 /* Build the tag after the MAC Source Address */ 163 return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN); 164 } 165 166 167 static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev, 168 struct packet_type *pt) 169 { 170 struct sk_buff *nskb; 171 172 /* skb->data points to the EtherType, the tag is right before it */ 173 nskb = brcm_tag_rcv_ll(skb, dev, pt, 2); 174 if (!nskb) 175 return nskb; 176 177 /* Move the Ethernet DA and SA */ 178 memmove(nskb->data - ETH_HLEN, 179 nskb->data - ETH_HLEN - BRCM_TAG_LEN, 180 2 * ETH_ALEN); 181 182 return nskb; 183 } 184 185 static const struct dsa_device_ops brcm_netdev_ops = { 186 .name = "brcm", 187 .proto = DSA_TAG_PROTO_BRCM, 188 .xmit = brcm_tag_xmit, 189 .rcv = brcm_tag_rcv, 190 .overhead = BRCM_TAG_LEN, 191 }; 192 193 DSA_TAG_DRIVER(brcm_netdev_ops); 194 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM); 195 #endif 196 197 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND) 198 static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb, 199 struct net_device *dev) 200 { 201 /* tag is prepended to the packet */ 202 return brcm_tag_xmit_ll(skb, dev, 0); 203 } 204 205 static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb, 206 struct net_device *dev, 207 struct packet_type *pt) 208 { 209 /* tag is prepended to the packet */ 210 return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN); 211 } 212 213 static const struct dsa_device_ops brcm_prepend_netdev_ops = { 214 .name = "brcm-prepend", 215 .proto = DSA_TAG_PROTO_BRCM_PREPEND, 216 .xmit = brcm_tag_xmit_prepend, 217 .rcv = brcm_tag_rcv_prepend, 218 .overhead = BRCM_TAG_LEN, 219 }; 220 221 DSA_TAG_DRIVER(brcm_prepend_netdev_ops); 222 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_PREPEND); 223 #endif 224 225 static struct dsa_tag_driver *dsa_tag_driver_array[] = { 226 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM) 227 &DSA_TAG_DRIVER_NAME(brcm_netdev_ops), 228 #endif 229 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND) 230 &DSA_TAG_DRIVER_NAME(brcm_prepend_netdev_ops), 231 #endif 232 }; 233 234 module_dsa_tag_drivers(dsa_tag_driver_array); 235 236 MODULE_LICENSE("GPL"); 237