1 // SPDX-License-Identifier: GPL-2.0 2 /* Copyright (c) 2019, Vladimir Oltean <olteanv@gmail.com> 3 */ 4 #include <linux/if_vlan.h> 5 #include <linux/dsa/sja1105.h> 6 #include <linux/dsa/8021q.h> 7 #include <linux/packing.h> 8 #include "dsa_priv.h" 9 10 /* Similar to is_link_local_ether_addr(hdr->h_dest) but also covers PTP */ 11 static inline bool sja1105_is_link_local(const struct sk_buff *skb) 12 { 13 const struct ethhdr *hdr = eth_hdr(skb); 14 u64 dmac = ether_addr_to_u64(hdr->h_dest); 15 16 if (ntohs(hdr->h_proto) == ETH_P_SJA1105_META) 17 return false; 18 if ((dmac & SJA1105_LINKLOCAL_FILTER_A_MASK) == 19 SJA1105_LINKLOCAL_FILTER_A) 20 return true; 21 if ((dmac & SJA1105_LINKLOCAL_FILTER_B_MASK) == 22 SJA1105_LINKLOCAL_FILTER_B) 23 return true; 24 return false; 25 } 26 27 struct sja1105_meta { 28 u64 tstamp; 29 u64 dmac_byte_4; 30 u64 dmac_byte_3; 31 u64 source_port; 32 u64 switch_id; 33 }; 34 35 static void sja1105_meta_unpack(const struct sk_buff *skb, 36 struct sja1105_meta *meta) 37 { 38 u8 *buf = skb_mac_header(skb) + ETH_HLEN; 39 40 /* UM10944.pdf section 4.2.17 AVB Parameters: 41 * Structure of the meta-data follow-up frame. 42 * It is in network byte order, so there are no quirks 43 * while unpacking the meta frame. 44 * 45 * Also SJA1105 E/T only populates bits 23:0 of the timestamp 46 * whereas P/Q/R/S does 32 bits. Since the structure is the 47 * same and the E/T puts zeroes in the high-order byte, use 48 * a unified unpacking command for both device series. 49 */ 50 packing(buf, &meta->tstamp, 31, 0, 4, UNPACK, 0); 51 packing(buf + 4, &meta->dmac_byte_4, 7, 0, 1, UNPACK, 0); 52 packing(buf + 5, &meta->dmac_byte_3, 7, 0, 1, UNPACK, 0); 53 packing(buf + 6, &meta->source_port, 7, 0, 1, UNPACK, 0); 54 packing(buf + 7, &meta->switch_id, 7, 0, 1, UNPACK, 0); 55 } 56 57 static inline bool sja1105_is_meta_frame(const struct sk_buff *skb) 58 { 59 const struct ethhdr *hdr = eth_hdr(skb); 60 u64 smac = ether_addr_to_u64(hdr->h_source); 61 u64 dmac = ether_addr_to_u64(hdr->h_dest); 62 63 if (smac != SJA1105_META_SMAC) 64 return false; 65 if (dmac != SJA1105_META_DMAC) 66 return false; 67 if (ntohs(hdr->h_proto) != ETH_P_SJA1105_META) 68 return false; 69 return true; 70 } 71 72 /* This is the first time the tagger sees the frame on RX. 73 * Figure out if we can decode it. 74 */ 75 static bool sja1105_filter(const struct sk_buff *skb, struct net_device *dev) 76 { 77 if (!dsa_port_is_vlan_filtering(dev->dsa_ptr)) 78 return true; 79 if (sja1105_is_link_local(skb)) 80 return true; 81 if (sja1105_is_meta_frame(skb)) 82 return true; 83 return false; 84 } 85 86 static struct sk_buff *sja1105_xmit(struct sk_buff *skb, 87 struct net_device *netdev) 88 { 89 struct dsa_port *dp = dsa_slave_to_port(netdev); 90 struct dsa_switch *ds = dp->ds; 91 u16 tx_vid = dsa_8021q_tx_vid(ds, dp->index); 92 u16 queue_mapping = skb_get_queue_mapping(skb); 93 u8 pcp = netdev_txq_to_tc(netdev, queue_mapping); 94 95 /* Transmitting management traffic does not rely upon switch tagging, 96 * but instead SPI-installed management routes. Part 2 of this 97 * is the .port_deferred_xmit driver callback. 98 */ 99 if (unlikely(sja1105_is_link_local(skb))) 100 return dsa_defer_xmit(skb, netdev); 101 102 /* If we are under a vlan_filtering bridge, IP termination on 103 * switch ports based on 802.1Q tags is simply too brittle to 104 * be passable. So just defer to the dsa_slave_notag_xmit 105 * implementation. 106 */ 107 if (dsa_port_is_vlan_filtering(dp)) 108 return skb; 109 110 return dsa_8021q_xmit(skb, netdev, ETH_P_SJA1105, 111 ((pcp << VLAN_PRIO_SHIFT) | tx_vid)); 112 } 113 114 static void sja1105_transfer_meta(struct sk_buff *skb, 115 const struct sja1105_meta *meta) 116 { 117 struct ethhdr *hdr = eth_hdr(skb); 118 119 hdr->h_dest[3] = meta->dmac_byte_3; 120 hdr->h_dest[4] = meta->dmac_byte_4; 121 SJA1105_SKB_CB(skb)->meta_tstamp = meta->tstamp; 122 } 123 124 /* This is a simple state machine which follows the hardware mechanism of 125 * generating RX timestamps: 126 * 127 * After each timestampable skb (all traffic for which send_meta1 and 128 * send_meta0 is true, aka all MAC-filtered link-local traffic) a meta frame 129 * containing a partial timestamp is immediately generated by the switch and 130 * sent as a follow-up to the link-local frame on the CPU port. 131 * 132 * The meta frames have no unique identifier (such as sequence number) by which 133 * one may pair them to the correct timestampable frame. 134 * Instead, the switch has internal logic that ensures no frames are sent on 135 * the CPU port between a link-local timestampable frame and its corresponding 136 * meta follow-up. It also ensures strict ordering between ports (lower ports 137 * have higher priority towards the CPU port). For this reason, a per-port 138 * data structure is not needed/desirable. 139 * 140 * This function pairs the link-local frame with its partial timestamp from the 141 * meta follow-up frame. The full timestamp will be reconstructed later in a 142 * work queue. 143 */ 144 static struct sk_buff 145 *sja1105_rcv_meta_state_machine(struct sk_buff *skb, 146 struct sja1105_meta *meta, 147 bool is_link_local, 148 bool is_meta) 149 { 150 struct sja1105_port *sp; 151 struct dsa_port *dp; 152 153 dp = dsa_slave_to_port(skb->dev); 154 sp = dp->priv; 155 156 /* Step 1: A timestampable frame was received. 157 * Buffer it until we get its meta frame. 158 */ 159 if (is_link_local && sp->data->hwts_rx_en) { 160 spin_lock(&sp->data->meta_lock); 161 /* Was this a link-local frame instead of the meta 162 * that we were expecting? 163 */ 164 if (sp->data->stampable_skb) { 165 dev_err_ratelimited(dp->ds->dev, 166 "Expected meta frame, is %12llx " 167 "in the DSA master multicast filter?\n", 168 SJA1105_META_DMAC); 169 kfree_skb(sp->data->stampable_skb); 170 } 171 172 /* Hold a reference to avoid dsa_switch_rcv 173 * from freeing the skb. 174 */ 175 sp->data->stampable_skb = skb_get(skb); 176 spin_unlock(&sp->data->meta_lock); 177 178 /* Tell DSA we got nothing */ 179 return NULL; 180 181 /* Step 2: The meta frame arrived. 182 * Time to take the stampable skb out of the closet, annotate it 183 * with the partial timestamp, and pretend that we received it 184 * just now (basically masquerade the buffered frame as the meta 185 * frame, which serves no further purpose). 186 */ 187 } else if (is_meta) { 188 struct sk_buff *stampable_skb; 189 190 spin_lock(&sp->data->meta_lock); 191 192 stampable_skb = sp->data->stampable_skb; 193 sp->data->stampable_skb = NULL; 194 195 /* Was this a meta frame instead of the link-local 196 * that we were expecting? 197 */ 198 if (!stampable_skb) { 199 dev_err_ratelimited(dp->ds->dev, 200 "Unexpected meta frame\n"); 201 spin_unlock(&sp->data->meta_lock); 202 return NULL; 203 } 204 205 if (stampable_skb->dev != skb->dev) { 206 dev_err_ratelimited(dp->ds->dev, 207 "Meta frame on wrong port\n"); 208 spin_unlock(&sp->data->meta_lock); 209 return NULL; 210 } 211 212 /* Free the meta frame and give DSA the buffered stampable_skb 213 * for further processing up the network stack. 214 */ 215 kfree_skb(skb); 216 skb = stampable_skb; 217 sja1105_transfer_meta(skb, meta); 218 219 spin_unlock(&sp->data->meta_lock); 220 } 221 222 return skb; 223 } 224 225 static struct sk_buff *sja1105_rcv(struct sk_buff *skb, 226 struct net_device *netdev, 227 struct packet_type *pt) 228 { 229 struct sja1105_meta meta = {0}; 230 int source_port, switch_id; 231 struct vlan_ethhdr *hdr; 232 u16 tpid, vid, tci; 233 bool is_link_local; 234 bool is_tagged; 235 bool is_meta; 236 237 hdr = vlan_eth_hdr(skb); 238 tpid = ntohs(hdr->h_vlan_proto); 239 is_tagged = (tpid == ETH_P_SJA1105); 240 is_link_local = sja1105_is_link_local(skb); 241 is_meta = sja1105_is_meta_frame(skb); 242 243 skb->offload_fwd_mark = 1; 244 245 if (is_tagged) { 246 /* Normal traffic path. */ 247 tci = ntohs(hdr->h_vlan_TCI); 248 vid = tci & VLAN_VID_MASK; 249 source_port = dsa_8021q_rx_source_port(vid); 250 switch_id = dsa_8021q_rx_switch_id(vid); 251 skb->priority = (tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT; 252 } else if (is_link_local) { 253 /* Management traffic path. Switch embeds the switch ID and 254 * port ID into bytes of the destination MAC, courtesy of 255 * the incl_srcpt options. 256 */ 257 source_port = hdr->h_dest[3]; 258 switch_id = hdr->h_dest[4]; 259 /* Clear the DMAC bytes that were mangled by the switch */ 260 hdr->h_dest[3] = 0; 261 hdr->h_dest[4] = 0; 262 } else if (is_meta) { 263 sja1105_meta_unpack(skb, &meta); 264 source_port = meta.source_port; 265 switch_id = meta.switch_id; 266 } else { 267 return NULL; 268 } 269 270 skb->dev = dsa_master_find_slave(netdev, switch_id, source_port); 271 if (!skb->dev) { 272 netdev_warn(netdev, "Couldn't decode source port\n"); 273 return NULL; 274 } 275 276 /* Delete/overwrite fake VLAN header, DSA expects to not find 277 * it there, see dsa_switch_rcv: skb_push(skb, ETH_HLEN). 278 */ 279 if (is_tagged) 280 skb = dsa_8021q_remove_header(skb); 281 282 return sja1105_rcv_meta_state_machine(skb, &meta, is_link_local, 283 is_meta); 284 } 285 286 static struct dsa_device_ops sja1105_netdev_ops = { 287 .name = "sja1105", 288 .proto = DSA_TAG_PROTO_SJA1105, 289 .xmit = sja1105_xmit, 290 .rcv = sja1105_rcv, 291 .filter = sja1105_filter, 292 .overhead = VLAN_HLEN, 293 }; 294 295 MODULE_LICENSE("GPL v2"); 296 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_SJA1105); 297 298 module_dsa_tag_driver(sja1105_netdev_ops); 299