1 /* 2 * Broadcom tag support 3 * 4 * Copyright (C) 2014 Broadcom Corporation 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 */ 11 12 #include <linux/etherdevice.h> 13 #include <linux/list.h> 14 #include <linux/slab.h> 15 16 #include "dsa_priv.h" 17 18 /* This tag length is 4 bytes, older ones were 6 bytes, we do not 19 * handle them 20 */ 21 #define BRCM_TAG_LEN 4 22 23 /* Tag is constructed and desconstructed using byte by byte access 24 * because the tag is placed after the MAC Source Address, which does 25 * not make it 4-bytes aligned, so this might cause unaligned accesses 26 * on most systems where this is used. 27 */ 28 29 /* Ingress and egress opcodes */ 30 #define BRCM_OPCODE_SHIFT 5 31 #define BRCM_OPCODE_MASK 0x7 32 33 /* Ingress fields */ 34 /* 1st byte in the tag */ 35 #define BRCM_IG_TC_SHIFT 2 36 #define BRCM_IG_TC_MASK 0x7 37 /* 2nd byte in the tag */ 38 #define BRCM_IG_TE_MASK 0x3 39 #define BRCM_IG_TS_SHIFT 7 40 /* 3rd byte in the tag */ 41 #define BRCM_IG_DSTMAP2_MASK 1 42 #define BRCM_IG_DSTMAP1_MASK 0xff 43 44 /* Egress fields */ 45 46 /* 2nd byte in the tag */ 47 #define BRCM_EG_CID_MASK 0xff 48 49 /* 3rd byte in the tag */ 50 #define BRCM_EG_RC_MASK 0xff 51 #define BRCM_EG_RC_RSVD (3 << 6) 52 #define BRCM_EG_RC_EXCEPTION (1 << 5) 53 #define BRCM_EG_RC_PROT_SNOOP (1 << 4) 54 #define BRCM_EG_RC_PROT_TERM (1 << 3) 55 #define BRCM_EG_RC_SWITCH (1 << 2) 56 #define BRCM_EG_RC_MAC_LEARN (1 << 1) 57 #define BRCM_EG_RC_MIRROR (1 << 0) 58 #define BRCM_EG_TC_SHIFT 5 59 #define BRCM_EG_TC_MASK 0x7 60 #define BRCM_EG_PID_MASK 0x1f 61 62 static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb, 63 struct net_device *dev, 64 unsigned int offset) 65 { 66 struct dsa_port *dp = dsa_slave_to_port(dev); 67 u16 queue = skb_get_queue_mapping(skb); 68 u8 *brcm_tag; 69 70 if (skb_cow_head(skb, BRCM_TAG_LEN) < 0) 71 return NULL; 72 73 /* The Ethernet switch we are interfaced with needs packets to be at 74 * least 64 bytes (including FCS) otherwise they will be discarded when 75 * they enter the switch port logic. When Broadcom tags are enabled, we 76 * need to make sure that packets are at least 68 bytes 77 * (including FCS and tag) because the length verification is done after 78 * the Broadcom tag is stripped off the ingress packet. 79 * 80 * Let dsa_slave_xmit() free the SKB 81 */ 82 if (__skb_put_padto(skb, ETH_ZLEN + BRCM_TAG_LEN, false)) 83 return NULL; 84 85 skb_push(skb, BRCM_TAG_LEN); 86 87 if (offset) 88 memmove(skb->data, skb->data + BRCM_TAG_LEN, offset); 89 90 brcm_tag = skb->data + offset; 91 92 /* Set the ingress opcode, traffic class, tag enforcment is 93 * deprecated 94 */ 95 brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) | 96 ((queue & BRCM_IG_TC_MASK) << BRCM_IG_TC_SHIFT); 97 brcm_tag[1] = 0; 98 brcm_tag[2] = 0; 99 if (dp->index == 8) 100 brcm_tag[2] = BRCM_IG_DSTMAP2_MASK; 101 brcm_tag[3] = (1 << dp->index) & BRCM_IG_DSTMAP1_MASK; 102 103 /* Now tell the master network device about the desired output queue 104 * as well 105 */ 106 skb_set_queue_mapping(skb, BRCM_TAG_SET_PORT_QUEUE(dp->index, queue)); 107 108 return skb; 109 } 110 111 static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb, 112 struct net_device *dev, 113 struct packet_type *pt, 114 unsigned int offset) 115 { 116 int source_port; 117 u8 *brcm_tag; 118 119 if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN))) 120 return NULL; 121 122 brcm_tag = skb->data - offset; 123 124 /* The opcode should never be different than 0b000 */ 125 if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK)) 126 return NULL; 127 128 /* We should never see a reserved reason code without knowing how to 129 * handle it 130 */ 131 if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD)) 132 return NULL; 133 134 /* Locate which port this is coming from */ 135 source_port = brcm_tag[3] & BRCM_EG_PID_MASK; 136 137 skb->dev = dsa_master_find_slave(dev, 0, source_port); 138 if (!skb->dev) 139 return NULL; 140 141 /* Remove Broadcom tag and update checksum */ 142 skb_pull_rcsum(skb, BRCM_TAG_LEN); 143 144 return skb; 145 } 146 147 #ifdef 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 const struct dsa_device_ops brcm_netdev_ops = { 175 .xmit = brcm_tag_xmit, 176 .rcv = brcm_tag_rcv, 177 }; 178 #endif 179 180 #ifdef CONFIG_NET_DSA_TAG_BRCM_PREPEND 181 static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb, 182 struct net_device *dev) 183 { 184 /* tag is prepended to the packet */ 185 return brcm_tag_xmit_ll(skb, dev, 0); 186 } 187 188 static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb, 189 struct net_device *dev, 190 struct packet_type *pt) 191 { 192 /* tag is prepended to the packet */ 193 return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN); 194 } 195 196 const struct dsa_device_ops brcm_prepend_netdev_ops = { 197 .xmit = brcm_tag_xmit_prepend, 198 .rcv = brcm_tag_rcv_prepend, 199 }; 200 #endif 201