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 if (skb_cow_head(skb, BRCM_TAG_LEN) < 0) 70 return NULL; 71 72 /* The Ethernet switch we are interfaced with needs packets to be at 73 * least 64 bytes (including FCS) otherwise they will be discarded when 74 * they enter the switch port logic. When Broadcom tags are enabled, we 75 * need to make sure that packets are at least 68 bytes 76 * (including FCS and tag) because the length verification is done after 77 * the Broadcom tag is stripped off the ingress packet. 78 * 79 * Let dsa_slave_xmit() free the SKB 80 */ 81 if (__skb_put_padto(skb, ETH_ZLEN + BRCM_TAG_LEN, false)) 82 return NULL; 83 84 skb_push(skb, BRCM_TAG_LEN); 85 86 if (offset) 87 memmove(skb->data, skb->data + BRCM_TAG_LEN, offset); 88 89 brcm_tag = skb->data + offset; 90 91 /* Set the ingress opcode, traffic class, tag enforcment is 92 * deprecated 93 */ 94 brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) | 95 ((queue & BRCM_IG_TC_MASK) << BRCM_IG_TC_SHIFT); 96 brcm_tag[1] = 0; 97 brcm_tag[2] = 0; 98 if (dp->index == 8) 99 brcm_tag[2] = BRCM_IG_DSTMAP2_MASK; 100 brcm_tag[3] = (1 << dp->index) & BRCM_IG_DSTMAP1_MASK; 101 102 /* Now tell the master network device about the desired output queue 103 * as well 104 */ 105 skb_set_queue_mapping(skb, BRCM_TAG_SET_PORT_QUEUE(dp->index, queue)); 106 107 return skb; 108 } 109 110 static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb, 111 struct net_device *dev, 112 struct packet_type *pt, 113 unsigned int offset) 114 { 115 int source_port; 116 u8 *brcm_tag; 117 118 if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN))) 119 return NULL; 120 121 brcm_tag = skb->data - offset; 122 123 /* The opcode should never be different than 0b000 */ 124 if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK)) 125 return NULL; 126 127 /* We should never see a reserved reason code without knowing how to 128 * handle it 129 */ 130 if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD)) 131 return NULL; 132 133 /* Locate which port this is coming from */ 134 source_port = brcm_tag[3] & BRCM_EG_PID_MASK; 135 136 skb->dev = dsa_master_find_slave(dev, 0, source_port); 137 if (!skb->dev) 138 return NULL; 139 140 /* Remove Broadcom tag and update checksum */ 141 skb_pull_rcsum(skb, BRCM_TAG_LEN); 142 143 return skb; 144 } 145 #endif 146 147 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM) 148 static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb, 149 struct net_device *dev) 150 { 151 /* Build the tag after the MAC Source Address */ 152 return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN); 153 } 154 155 156 static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev, 157 struct packet_type *pt) 158 { 159 struct sk_buff *nskb; 160 161 /* skb->data points to the EtherType, the tag is right before it */ 162 nskb = brcm_tag_rcv_ll(skb, dev, pt, 2); 163 if (!nskb) 164 return nskb; 165 166 /* Move the Ethernet DA and SA */ 167 memmove(nskb->data - ETH_HLEN, 168 nskb->data - ETH_HLEN - BRCM_TAG_LEN, 169 2 * ETH_ALEN); 170 171 return nskb; 172 } 173 174 static const struct dsa_device_ops brcm_netdev_ops = { 175 .name = "brcm", 176 .proto = DSA_TAG_PROTO_BRCM, 177 .xmit = brcm_tag_xmit, 178 .rcv = brcm_tag_rcv, 179 .overhead = BRCM_TAG_LEN, 180 }; 181 182 DSA_TAG_DRIVER(brcm_netdev_ops); 183 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM); 184 #endif 185 186 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND) 187 static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb, 188 struct net_device *dev) 189 { 190 /* tag is prepended to the packet */ 191 return brcm_tag_xmit_ll(skb, dev, 0); 192 } 193 194 static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb, 195 struct net_device *dev, 196 struct packet_type *pt) 197 { 198 /* tag is prepended to the packet */ 199 return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN); 200 } 201 202 static const struct dsa_device_ops brcm_prepend_netdev_ops = { 203 .name = "brcm-prepend", 204 .proto = DSA_TAG_PROTO_BRCM_PREPEND, 205 .xmit = brcm_tag_xmit_prepend, 206 .rcv = brcm_tag_rcv_prepend, 207 .overhead = BRCM_TAG_LEN, 208 }; 209 210 DSA_TAG_DRIVER(brcm_prepend_netdev_ops); 211 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_PREPEND); 212 #endif 213 214 static struct dsa_tag_driver *dsa_tag_driver_array[] = { 215 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM) 216 &DSA_TAG_DRIVER_NAME(brcm_netdev_ops), 217 #endif 218 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND) 219 &DSA_TAG_DRIVER_NAME(brcm_prepend_netdev_ops), 220 #endif 221 }; 222 223 module_dsa_tag_drivers(dsa_tag_driver_array); 224 225 MODULE_LICENSE("GPL"); 226