1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2019, Vladimir Oltean <olteanv@gmail.com>
4 #include <linux/if_vlan.h>
5 #include <linux/dsa/sja1105.h>
6 #include <linux/dsa/8021q.h>
7 #include <linux/packing.h>
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)
13 const struct ethhdr *hdr = eth_hdr(skb);
14 u64 dmac = ether_addr_to_u64(hdr->h_dest);
16 if (ntohs(hdr->h_proto) == ETH_P_SJA1105_META)
18 if ((dmac & SJA1105_LINKLOCAL_FILTER_A_MASK) ==
19 SJA1105_LINKLOCAL_FILTER_A)
21 if ((dmac & SJA1105_LINKLOCAL_FILTER_B_MASK) ==
22 SJA1105_LINKLOCAL_FILTER_B)
35 static void sja1105_meta_unpack(const struct sk_buff *skb,
36 struct sja1105_meta *meta)
38 u8 *buf = skb_mac_header(skb) + ETH_HLEN;
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.
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.
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);
57 static inline bool sja1105_is_meta_frame(const struct sk_buff *skb)
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);
63 if (smac != SJA1105_META_SMAC)
65 if (dmac != SJA1105_META_DMAC)
67 if (ntohs(hdr->h_proto) != ETH_P_SJA1105_META)
72 /* This is the first time the tagger sees the frame on RX.
73 * Figure out if we can decode it.
75 static bool sja1105_filter(const struct sk_buff *skb, struct net_device *dev)
77 if (!dsa_port_is_vlan_filtering(dev->dsa_ptr))
79 if (sja1105_is_link_local(skb))
81 if (sja1105_is_meta_frame(skb))
86 static struct sk_buff *sja1105_xmit(struct sk_buff *skb,
87 struct net_device *netdev)
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;
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.
98 if (unlikely(sja1105_is_link_local(skb)))
99 return dsa_defer_xmit(skb, netdev);
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
106 if (dsa_port_is_vlan_filtering(dp))
109 return dsa_8021q_xmit(skb, netdev, ETH_P_SJA1105,
110 ((pcp << VLAN_PRIO_SHIFT) | tx_vid));
113 static void sja1105_transfer_meta(struct sk_buff *skb,
114 const struct sja1105_meta *meta)
116 struct ethhdr *hdr = eth_hdr(skb);
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;
123 /* This is a simple state machine which follows the hardware mechanism of
124 * generating RX timestamps:
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.
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.
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
143 static struct sk_buff
144 *sja1105_rcv_meta_state_machine(struct sk_buff *skb,
145 struct sja1105_meta *meta,
149 struct sja1105_port *sp;
152 dp = dsa_slave_to_port(skb->dev);
155 /* Step 1: A timestampable frame was received.
156 * Buffer it until we get its meta frame.
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?
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",
168 kfree_skb(sp->data->stampable_skb);
171 /* Hold a reference to avoid dsa_switch_rcv
172 * from freeing the skb.
174 sp->data->stampable_skb = skb_get(skb);
175 spin_unlock(&sp->data->meta_lock);
177 /* Tell DSA we got nothing */
180 /* Step 2: The meta frame arrived.
181 * Time to take the stampable skb out of the closet, annotate it
182 * with the partial timestamp, and pretend that we received it
183 * just now (basically masquerade the buffered frame as the meta
184 * frame, which serves no further purpose).
186 } else if (is_meta) {
187 struct sk_buff *stampable_skb;
189 spin_lock(&sp->data->meta_lock);
191 stampable_skb = sp->data->stampable_skb;
192 sp->data->stampable_skb = NULL;
194 /* Was this a meta frame instead of the link-local
195 * that we were expecting?
197 if (!stampable_skb) {
198 dev_err_ratelimited(dp->ds->dev,
199 "Unexpected meta frame\n");
200 spin_unlock(&sp->data->meta_lock);
204 if (stampable_skb->dev != skb->dev) {
205 dev_err_ratelimited(dp->ds->dev,
206 "Meta frame on wrong port\n");
207 spin_unlock(&sp->data->meta_lock);
211 /* Free the meta frame and give DSA the buffered stampable_skb
212 * for further processing up the network stack.
216 sja1105_transfer_meta(skb, meta);
218 spin_unlock(&sp->data->meta_lock);
224 static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
225 struct net_device *netdev,
226 struct packet_type *pt)
228 struct sja1105_meta meta = {0};
229 int source_port, switch_id;
230 struct vlan_ethhdr *hdr;
236 hdr = vlan_eth_hdr(skb);
237 tpid = ntohs(hdr->h_vlan_proto);
238 is_tagged = (tpid == ETH_P_SJA1105);
239 is_link_local = sja1105_is_link_local(skb);
240 is_meta = sja1105_is_meta_frame(skb);
242 skb->offload_fwd_mark = 1;
245 /* Normal traffic path. */
246 tci = ntohs(hdr->h_vlan_TCI);
247 vid = tci & VLAN_VID_MASK;
248 source_port = dsa_8021q_rx_source_port(vid);
249 switch_id = dsa_8021q_rx_switch_id(vid);
250 skb->priority = (tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
251 } else if (is_link_local) {
252 /* Management traffic path. Switch embeds the switch ID and
253 * port ID into bytes of the destination MAC, courtesy of
254 * the incl_srcpt options.
256 source_port = hdr->h_dest[3];
257 switch_id = hdr->h_dest[4];
258 /* Clear the DMAC bytes that were mangled by the switch */
261 } else if (is_meta) {
262 sja1105_meta_unpack(skb, &meta);
263 source_port = meta.source_port;
264 switch_id = meta.switch_id;
269 skb->dev = dsa_master_find_slave(netdev, switch_id, source_port);
271 netdev_warn(netdev, "Couldn't decode source port\n");
275 /* Delete/overwrite fake VLAN header, DSA expects to not find
276 * it there, see dsa_switch_rcv: skb_push(skb, ETH_HLEN).
279 skb = dsa_8021q_remove_header(skb);
281 return sja1105_rcv_meta_state_machine(skb, &meta, is_link_local,
285 static struct dsa_device_ops sja1105_netdev_ops = {
287 .proto = DSA_TAG_PROTO_SJA1105,
288 .xmit = sja1105_xmit,
290 .filter = sja1105_filter,
291 .overhead = VLAN_HLEN,
294 MODULE_LICENSE("GPL v2");
295 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_SJA1105);
297 module_dsa_tag_driver(sja1105_netdev_ops);