net/dsa/tag_sja1105.c

   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 /* Calls sja1105_port_deferred_xmit in sja1105_main.c */
  87 static struct sk_buff *sja1105_defer_xmit(struct sja1105_port *sp,
  88                                           struct sk_buff *skb)
  89 {
  90         /* Increase refcount so the kfree_skb in dsa_slave_xmit
  91          * won't really free the packet.
  92          */
  93         skb_queue_tail(&sp->xmit_queue, skb_get(skb));
  94         kthread_queue_work(sp->xmit_worker, &sp->xmit_work);
  95
  96         return NULL;
  97 }
  98
  99 static struct sk_buff *sja1105_xmit(struct sk_buff *skb,
 100                                     struct net_device *netdev)
 101 {
 102         struct dsa_port *dp = dsa_slave_to_port(netdev);
 103         u16 tx_vid = dsa_8021q_tx_vid(dp->ds, dp->index);
 104         u16 queue_mapping = skb_get_queue_mapping(skb);
 105         u8 pcp = netdev_txq_to_tc(netdev, queue_mapping);
 106
 107         /* Transmitting management traffic does not rely upon switch tagging,
 108          * but instead SPI-installed management routes. Part 2 of this
 109          * is the .port_deferred_xmit driver callback.
 110          */
 111         if (unlikely(sja1105_is_link_local(skb)))
 112                 return sja1105_defer_xmit(dp->priv, skb);
 113
 114         /* If we are under a vlan_filtering bridge, IP termination on
 115          * switch ports based on 802.1Q tags is simply too brittle to
 116          * be passable. So just defer to the dsa_slave_notag_xmit
 117          * implementation.
 118          */
 119         if (dsa_port_is_vlan_filtering(dp))
 120                 return skb;
 121
 122         return dsa_8021q_xmit(skb, netdev, ETH_P_SJA1105,
 123                              ((pcp << VLAN_PRIO_SHIFT) | tx_vid));
 124 }
 125
 126 static void sja1105_transfer_meta(struct sk_buff *skb,
 127                                   const struct sja1105_meta *meta)
 128 {
 129         struct ethhdr *hdr = eth_hdr(skb);
 130
 131         hdr->h_dest[3] = meta->dmac_byte_3;
 132         hdr->h_dest[4] = meta->dmac_byte_4;
 133         SJA1105_SKB_CB(skb)->meta_tstamp = meta->tstamp;
 134 }
 135
 136 /* This is a simple state machine which follows the hardware mechanism of
 137  * generating RX timestamps:
 138  *
 139  * After each timestampable skb (all traffic for which send_meta1 and
 140  * send_meta0 is true, aka all MAC-filtered link-local traffic) a meta frame
 141  * containing a partial timestamp is immediately generated by the switch and
 142  * sent as a follow-up to the link-local frame on the CPU port.
 143  *
 144  * The meta frames have no unique identifier (such as sequence number) by which
 145  * one may pair them to the correct timestampable frame.
 146  * Instead, the switch has internal logic that ensures no frames are sent on
 147  * the CPU port between a link-local timestampable frame and its corresponding
 148  * meta follow-up. It also ensures strict ordering between ports (lower ports
 149  * have higher priority towards the CPU port). For this reason, a per-port
 150  * data structure is not needed/desirable.
 151  *
 152  * This function pairs the link-local frame with its partial timestamp from the
 153  * meta follow-up frame. The full timestamp will be reconstructed later in a
 154  * work queue.
 155  */
 156 static struct sk_buff
 157 *sja1105_rcv_meta_state_machine(struct sk_buff *skb,
 158                                 struct sja1105_meta *meta,
 159                                 bool is_link_local,
 160                                 bool is_meta)
 161 {
 162         struct sja1105_port *sp;
 163         struct dsa_port *dp;
 164
 165         dp = dsa_slave_to_port(skb->dev);
 166         sp = dp->priv;
 167
 168         /* Step 1: A timestampable frame was received.
 169          * Buffer it until we get its meta frame.
 170          */
 171         if (is_link_local) {
 172                 if (!test_bit(SJA1105_HWTS_RX_EN, &sp->data->state))
 173                         /* Do normal processing. */
 174                         return skb;
 175
 176                 spin_lock(&sp->data->meta_lock);
 177                 /* Was this a link-local frame instead of the meta
 178                  * that we were expecting?
 179                  */
 180                 if (sp->data->stampable_skb) {
 181                         dev_err_ratelimited(dp->ds->dev,
 182                                             "Expected meta frame, is %12llx "
 183                                             "in the DSA master multicast filter?\n",
 184                                             SJA1105_META_DMAC);
 185                         kfree_skb(sp->data->stampable_skb);
 186                 }
 187
 188                 /* Hold a reference to avoid dsa_switch_rcv
 189                  * from freeing the skb.
 190                  */
 191                 sp->data->stampable_skb = skb_get(skb);
 192                 spin_unlock(&sp->data->meta_lock);
 193
 194                 /* Tell DSA we got nothing */
 195                 return NULL;
 196
 197         /* Step 2: The meta frame arrived.
 198          * Time to take the stampable skb out of the closet, annotate it
 199          * with the partial timestamp, and pretend that we received it
 200          * just now (basically masquerade the buffered frame as the meta
 201          * frame, which serves no further purpose).
 202          */
 203         } else if (is_meta) {
 204                 struct sk_buff *stampable_skb;
 205
 206                 /* Drop the meta frame if we're not in the right state
 207                  * to process it.
 208                  */
 209                 if (!test_bit(SJA1105_HWTS_RX_EN, &sp->data->state))
 210                         return NULL;
 211
 212                 spin_lock(&sp->data->meta_lock);
 213
 214                 stampable_skb = sp->data->stampable_skb;
 215                 sp->data->stampable_skb = NULL;
 216
 217                 /* Was this a meta frame instead of the link-local
 218                  * that we were expecting?
 219                  */
 220                 if (!stampable_skb) {
 221                         dev_err_ratelimited(dp->ds->dev,
 222                                             "Unexpected meta frame\n");
 223                         spin_unlock(&sp->data->meta_lock);
 224                         return NULL;
 225                 }
 226
 227                 if (stampable_skb->dev != skb->dev) {
 228                         dev_err_ratelimited(dp->ds->dev,
 229                                             "Meta frame on wrong port\n");
 230                         spin_unlock(&sp->data->meta_lock);
 231                         return NULL;
 232                 }
 233
 234                 /* Free the meta frame and give DSA the buffered stampable_skb
 235                  * for further processing up the network stack.
 236                  */
 237                 kfree_skb(skb);
 238                 skb = stampable_skb;
 239                 sja1105_transfer_meta(skb, meta);
 240
 241                 spin_unlock(&sp->data->meta_lock);
 242         }
 243
 244         return skb;
 245 }
 246
 247 static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
 248                                    struct net_device *netdev,
 249                                    struct packet_type *pt)
 250 {
 251         struct sja1105_meta meta = {0};
 252         int source_port, switch_id;
 253         struct ethhdr *hdr;
 254         u16 tpid, vid, tci;
 255         bool is_link_local;
 256         bool is_tagged;
 257         bool is_meta;
 258
 259         hdr = eth_hdr(skb);
 260         tpid = ntohs(hdr->h_proto);
 261         is_tagged = (tpid == ETH_P_SJA1105);
 262         is_link_local = sja1105_is_link_local(skb);
 263         is_meta = sja1105_is_meta_frame(skb);
 264
 265         skb->offload_fwd_mark = 1;
 266
 267         if (is_tagged) {
 268                 /* Normal traffic path. */
 269                 skb_push_rcsum(skb, ETH_HLEN);
 270                 __skb_vlan_pop(skb, &tci);
 271                 skb_pull_rcsum(skb, ETH_HLEN);
 272                 skb_reset_network_header(skb);
 273                 skb_reset_transport_header(skb);
 274
 275                 vid = tci & VLAN_VID_MASK;
 276                 source_port = dsa_8021q_rx_source_port(vid);
 277                 switch_id = dsa_8021q_rx_switch_id(vid);
 278                 skb->priority = (tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
 279         } else if (is_link_local) {
 280                 /* Management traffic path. Switch embeds the switch ID and
 281                  * port ID into bytes of the destination MAC, courtesy of
 282                  * the incl_srcpt options.
 283                  */
 284                 source_port = hdr->h_dest[3];
 285                 switch_id = hdr->h_dest[4];
 286                 /* Clear the DMAC bytes that were mangled by the switch */
 287                 hdr->h_dest[3] = 0;
 288                 hdr->h_dest[4] = 0;
 289         } else if (is_meta) {
 290                 sja1105_meta_unpack(skb, &meta);
 291                 source_port = meta.source_port;
 292                 switch_id = meta.switch_id;
 293         } else {
 294                 return NULL;
 295         }
 296
 297         skb->dev = dsa_master_find_slave(netdev, switch_id, source_port);
 298         if (!skb->dev) {
 299                 netdev_warn(netdev, "Couldn't decode source port\n");
 300                 return NULL;
 301         }
 302
 303         return sja1105_rcv_meta_state_machine(skb, &meta, is_link_local,
 304                                               is_meta);
 305 }
 306
 307 static struct dsa_device_ops sja1105_netdev_ops = {
 308         .name = "sja1105",
 309         .proto = DSA_TAG_PROTO_SJA1105,
 310         .xmit = sja1105_xmit,
 311         .rcv = sja1105_rcv,
 312         .filter = sja1105_filter,
 313         .overhead = VLAN_HLEN,
 314 };
 315
 316 MODULE_LICENSE("GPL v2");
 317 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_SJA1105);
 318
 319 module_dsa_tag_driver(sja1105_netdev_ops);