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 static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb, 59 struct net_device *dev, 60 unsigned int offset) 61 { 62 struct dsa_port *dp = dsa_slave_to_port(dev); 63 u16 queue = skb_get_queue_mapping(skb); 64 u8 *brcm_tag; 65 66 if (skb_cow_head(skb, BRCM_TAG_LEN) < 0) 67 return NULL; 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 static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb, 108 struct net_device *dev, 109 struct packet_type *pt, 110 unsigned int offset) 111 { 112 int source_port; 113 u8 *brcm_tag; 114 115 if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN))) 116 return NULL; 117 118 brcm_tag = skb->data - offset; 119 120 /* The opcode should never be different than 0b000 */ 121 if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK)) 122 return NULL; 123 124 /* We should never see a reserved reason code without knowing how to 125 * handle it 126 */ 127 if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD)) 128 return NULL; 129 130 /* Locate which port this is coming from */ 131 source_port = brcm_tag[3] & BRCM_EG_PID_MASK; 132 133 skb->dev = dsa_master_find_slave(dev, 0, source_port); 134 if (!skb->dev) 135 return NULL; 136 137 /* Remove Broadcom tag and update checksum */ 138 skb_pull_rcsum(skb, BRCM_TAG_LEN); 139 140 return skb; 141 } 142 143 #ifdef CONFIG_NET_DSA_TAG_BRCM 144 static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb, 145 struct net_device *dev) 146 { 147 /* Build the tag after the MAC Source Address */ 148 return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN); 149 } 150 151 152 static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev, 153 struct packet_type *pt) 154 { 155 struct sk_buff *nskb; 156 157 /* skb->data points to the EtherType, the tag is right before it */ 158 nskb = brcm_tag_rcv_ll(skb, dev, pt, 2); 159 if (!nskb) 160 return nskb; 161 162 /* Move the Ethernet DA and SA */ 163 memmove(nskb->data - ETH_HLEN, 164 nskb->data - ETH_HLEN - BRCM_TAG_LEN, 165 2 * ETH_ALEN); 166 167 return nskb; 168 } 169 170 const struct dsa_device_ops brcm_netdev_ops = { 171 .name = "brcm", 172 .proto = DSA_TAG_PROTO_BRCM, 173 .xmit = brcm_tag_xmit, 174 .rcv = brcm_tag_rcv, 175 .overhead = BRCM_TAG_LEN, 176 }; 177 178 DSA_TAG_DRIVER(brcm_netdev_ops); 179 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM); 180 #endif 181 182 #ifdef CONFIG_NET_DSA_TAG_BRCM_PREPEND 183 static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb, 184 struct net_device *dev) 185 { 186 /* tag is prepended to the packet */ 187 return brcm_tag_xmit_ll(skb, dev, 0); 188 } 189 190 static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb, 191 struct net_device *dev, 192 struct packet_type *pt) 193 { 194 /* tag is prepended to the packet */ 195 return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN); 196 } 197 198 const struct dsa_device_ops brcm_prepend_netdev_ops = { 199 .name = "brcm-prepend", 200 .proto = DSA_TAG_PROTO_BRCM_PREPEND, 201 .xmit = brcm_tag_xmit_prepend, 202 .rcv = brcm_tag_rcv_prepend, 203 .overhead = BRCM_TAG_LEN, 204 }; 205 #endif 206 207 DSA_TAG_DRIVER(brcm_prepend_netdev_ops); 208 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_PREPEND); 209 210 static struct dsa_tag_driver *dsa_tag_driver_array[] = { 211 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM) 212 &DSA_TAG_DRIVER_NAME(brcm_netdev_ops), 213 #endif 214 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND) 215 &DSA_TAG_DRIVER_NAME(brcm_prepend_netdev_ops), 216 #endif 217 }; 218 219 module_dsa_tag_drivers(dsa_tag_driver_array); 220 221 MODULE_LICENSE("GPL"); 222