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 u8 pcp = skb->priority; 93 94 /* Transmitting management traffic does not rely upon switch tagging, 95 * but instead SPI-installed management routes. Part 2 of this 96 * is the .port_deferred_xmit driver callback. 97 */ 98 if (unlikely(sja1105_is_link_local(skb))) 99 return dsa_defer_xmit(skb, netdev); 100 101 /* If we are under a vlan_filtering bridge, IP termination on 102 * switch ports based on 802.1Q tags is simply too brittle to 103 * be passable. So just defer to the dsa_slave_notag_xmit 104 * implementation. 105 */ 106 if (dsa_port_is_vlan_filtering(dp)) 107 return skb; 108 109 return dsa_8021q_xmit(skb, netdev, ETH_P_SJA1105, 110 ((pcp << VLAN_PRIO_SHIFT) | tx_vid)); 111 } 112 113 static void sja1105_transfer_meta(struct sk_buff *skb, 114 const struct sja1105_meta *meta) 115 { 116 struct ethhdr *hdr = eth_hdr(skb); 117 118 hdr->h_dest[3] = meta->dmac_byte_3; 119 hdr->h_dest[4] = meta->dmac_byte_4; 120 SJA1105_SKB_CB(skb)->meta_tstamp = meta->tstamp; 121 } 122 123 /* This is a simple state machine which follows the hardware mechanism of 124 * generating RX timestamps: 125 * 126 * After each timestampable skb (all traffic for which send_meta1 and 127 * send_meta0 is true, aka all MAC-filtered link-local traffic) a meta frame 128 * containing a partial timestamp is immediately generated by the switch and 129 * sent as a follow-up to the link-local frame on the CPU port. 130 * 131 * The meta frames have no unique identifier (such as sequence number) by which 132 * one may pair them to the correct timestampable frame. 133 * Instead, the switch has internal logic that ensures no frames are sent on 134 * the CPU port between a link-local timestampable frame and its corresponding 135 * meta follow-up. It also ensures strict ordering between ports (lower ports 136 * have higher priority towards the CPU port). For this reason, a per-port 137 * data structure is not needed/desirable. 138 * 139 * This function pairs the link-local frame with its partial timestamp from the 140 * meta follow-up frame. The full timestamp will be reconstructed later in a 141 * work queue. 142 */ 143 static struct sk_buff 144 *sja1105_rcv_meta_state_machine(struct sk_buff *skb, 145 struct sja1105_meta *meta, 146 bool is_link_local, 147 bool is_meta) 148 { 149 struct sja1105_port *sp; 150 struct dsa_port *dp; 151 152 dp = dsa_slave_to_port(skb->dev); 153 sp = dp->priv; 154 155 /* Step 1: A timestampable frame was received. 156 * Buffer it until we get its meta frame. 157 */ 158 if (is_link_local && sp->data->hwts_rx_en) { 159 spin_lock(&sp->data->meta_lock); 160 /* Was this a link-local frame instead of the meta 161 * that we were expecting? 162 */ 163 if (sp->data->stampable_skb) { 164 dev_err_ratelimited(dp->ds->dev, 165 "Expected meta frame, is %12llx " 166 "in the DSA master multicast filter?\n", 167 SJA1105_META_DMAC); 168 } 169 170 /* Hold a reference to avoid dsa_switch_rcv 171 * from freeing the skb. 172 */ 173 sp->data->stampable_skb = skb_get(skb); 174 spin_unlock(&sp->data->meta_lock); 175 176 /* Tell DSA we got nothing */ 177 return NULL; 178 179 /* Step 2: The meta frame arrived. 180 * Time to take the stampable skb out of the closet, annotate it 181 * with the partial timestamp, and pretend that we received it 182 * just now (basically masquerade the buffered frame as the meta 183 * frame, which serves no further purpose). 184 */ 185 } else if (is_meta) { 186 struct sk_buff *stampable_skb; 187 188 spin_lock(&sp->data->meta_lock); 189 190 stampable_skb = sp->data->stampable_skb; 191 sp->data->stampable_skb = NULL; 192 193 /* Was this a meta frame instead of the link-local 194 * that we were expecting? 195 */ 196 if (!stampable_skb) { 197 dev_err_ratelimited(dp->ds->dev, 198 "Unexpected meta frame\n"); 199 spin_unlock(&sp->data->meta_lock); 200 return NULL; 201 } 202 203 if (stampable_skb->dev != skb->dev) { 204 dev_err_ratelimited(dp->ds->dev, 205 "Meta frame on wrong port\n"); 206 spin_unlock(&sp->data->meta_lock); 207 return NULL; 208 } 209 210 /* Free the meta frame and give DSA the buffered stampable_skb 211 * for further processing up the network stack. 212 */ 213 kfree_skb(skb); 214 215 skb = skb_copy(stampable_skb, GFP_ATOMIC); 216 if (!skb) { 217 dev_err_ratelimited(dp->ds->dev, 218 "Failed to copy stampable skb\n"); 219 spin_unlock(&sp->data->meta_lock); 220 return NULL; 221 } 222 sja1105_transfer_meta(skb, meta); 223 /* The cached copy will be freed now */ 224 skb_unref(stampable_skb); 225 226 spin_unlock(&sp->data->meta_lock); 227 } 228 229 return skb; 230 } 231 232 static struct sk_buff *sja1105_rcv(struct sk_buff *skb, 233 struct net_device *netdev, 234 struct packet_type *pt) 235 { 236 struct sja1105_meta meta = {0}; 237 int source_port, switch_id; 238 struct vlan_ethhdr *hdr; 239 u16 tpid, vid, tci; 240 bool is_link_local; 241 bool is_tagged; 242 bool is_meta; 243 244 hdr = vlan_eth_hdr(skb); 245 tpid = ntohs(hdr->h_vlan_proto); 246 is_tagged = (tpid == ETH_P_SJA1105); 247 is_link_local = sja1105_is_link_local(skb); 248 is_meta = sja1105_is_meta_frame(skb); 249 250 skb->offload_fwd_mark = 1; 251 252 if (is_tagged) { 253 /* Normal traffic path. */ 254 tci = ntohs(hdr->h_vlan_TCI); 255 vid = tci & VLAN_VID_MASK; 256 source_port = dsa_8021q_rx_source_port(vid); 257 switch_id = dsa_8021q_rx_switch_id(vid); 258 skb->priority = (tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT; 259 } else if (is_link_local) { 260 /* Management traffic path. Switch embeds the switch ID and 261 * port ID into bytes of the destination MAC, courtesy of 262 * the incl_srcpt options. 263 */ 264 source_port = hdr->h_dest[3]; 265 switch_id = hdr->h_dest[4]; 266 /* Clear the DMAC bytes that were mangled by the switch */ 267 hdr->h_dest[3] = 0; 268 hdr->h_dest[4] = 0; 269 } else if (is_meta) { 270 sja1105_meta_unpack(skb, &meta); 271 source_port = meta.source_port; 272 switch_id = meta.switch_id; 273 } else { 274 return NULL; 275 } 276 277 skb->dev = dsa_master_find_slave(netdev, switch_id, source_port); 278 if (!skb->dev) { 279 netdev_warn(netdev, "Couldn't decode source port\n"); 280 return NULL; 281 } 282 283 /* Delete/overwrite fake VLAN header, DSA expects to not find 284 * it there, see dsa_switch_rcv: skb_push(skb, ETH_HLEN). 285 */ 286 if (is_tagged) 287 skb = dsa_8021q_remove_header(skb); 288 289 return sja1105_rcv_meta_state_machine(skb, &meta, is_link_local, 290 is_meta); 291 } 292 293 static struct dsa_device_ops sja1105_netdev_ops = { 294 .name = "sja1105", 295 .proto = DSA_TAG_PROTO_SJA1105, 296 .xmit = sja1105_xmit, 297 .rcv = sja1105_rcv, 298 .filter = sja1105_filter, 299 .overhead = VLAN_HLEN, 300 }; 301 302 MODULE_LICENSE("GPL v2"); 303 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_SJA1105); 304 305 module_dsa_tag_driver(sja1105_netdev_ops); 306