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 */
sja1105_is_link_local(const struct sk_buff * skb)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
sja1105_meta_unpack(const struct sk_buff * skb,struct sja1105_meta * meta)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
sja1105_is_meta_frame(const struct sk_buff * skb)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 */
sja1105_filter(const struct sk_buff * skb,struct net_device * dev)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
sja1105_xmit(struct sk_buff * skb,struct net_device * netdev)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
sja1105_transfer_meta(struct sk_buff * skb,const struct sja1105_meta * meta)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
sja1105_rcv_meta_state_machine(struct sk_buff * skb,struct sja1105_meta * meta,bool is_link_local,bool is_meta)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) {
160 if (!test_bit(SJA1105_HWTS_RX_EN, &sp->data->state))
161 /* Do normal processing. */
162 return skb;
163
164 spin_lock(&sp->data->meta_lock);
165 /* Was this a link-local frame instead of the meta
166 * that we were expecting?
167 */
168 if (sp->data->stampable_skb) {
169 dev_err_ratelimited(dp->ds->dev,
170 "Expected meta frame, is %12llx "
171 "in the DSA master multicast filter?\n",
172 SJA1105_META_DMAC);
173 kfree_skb(sp->data->stampable_skb);
174 }
175
176 /* Hold a reference to avoid dsa_switch_rcv
177 * from freeing the skb.
178 */
179 sp->data->stampable_skb = skb_get(skb);
180 spin_unlock(&sp->data->meta_lock);
181
182 /* Tell DSA we got nothing */
183 return NULL;
184
185 /* Step 2: The meta frame arrived.
186 * Time to take the stampable skb out of the closet, annotate it
187 * with the partial timestamp, and pretend that we received it
188 * just now (basically masquerade the buffered frame as the meta
189 * frame, which serves no further purpose).
190 */
191 } else if (is_meta) {
192 struct sk_buff *stampable_skb;
193
194 /* Drop the meta frame if we're not in the right state
195 * to process it.
196 */
197 if (!test_bit(SJA1105_HWTS_RX_EN, &sp->data->state))
198 return NULL;
199
200 spin_lock(&sp->data->meta_lock);
201
202 stampable_skb = sp->data->stampable_skb;
203 sp->data->stampable_skb = NULL;
204
205 /* Was this a meta frame instead of the link-local
206 * that we were expecting?
207 */
208 if (!stampable_skb) {
209 dev_err_ratelimited(dp->ds->dev,
210 "Unexpected meta frame\n");
211 spin_unlock(&sp->data->meta_lock);
212 return NULL;
213 }
214
215 if (stampable_skb->dev != skb->dev) {
216 dev_err_ratelimited(dp->ds->dev,
217 "Meta frame on wrong port\n");
218 spin_unlock(&sp->data->meta_lock);
219 return NULL;
220 }
221
222 /* Free the meta frame and give DSA the buffered stampable_skb
223 * for further processing up the network stack.
224 */
225 kfree_skb(skb);
226 skb = stampable_skb;
227 sja1105_transfer_meta(skb, meta);
228
229 spin_unlock(&sp->data->meta_lock);
230 }
231
232 return skb;
233 }
234
sja1105_rcv(struct sk_buff * skb,struct net_device * netdev,struct packet_type * pt)235 static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
236 struct net_device *netdev,
237 struct packet_type *pt)
238 {
239 struct sja1105_meta meta = {0};
240 int source_port, switch_id;
241 struct vlan_ethhdr *hdr;
242 u16 tpid, vid, tci;
243 bool is_link_local;
244 bool is_tagged;
245 bool is_meta;
246
247 hdr = vlan_eth_hdr(skb);
248 tpid = ntohs(hdr->h_vlan_proto);
249 is_tagged = (tpid == ETH_P_SJA1105);
250 is_link_local = sja1105_is_link_local(skb);
251 is_meta = sja1105_is_meta_frame(skb);
252
253 skb->offload_fwd_mark = 1;
254
255 if (is_tagged) {
256 /* Normal traffic path. */
257 tci = ntohs(hdr->h_vlan_TCI);
258 vid = tci & VLAN_VID_MASK;
259 source_port = dsa_8021q_rx_source_port(vid);
260 switch_id = dsa_8021q_rx_switch_id(vid);
261 skb->priority = (tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
262 } else if (is_link_local) {
263 /* Management traffic path. Switch embeds the switch ID and
264 * port ID into bytes of the destination MAC, courtesy of
265 * the incl_srcpt options.
266 */
267 source_port = hdr->h_dest[3];
268 switch_id = hdr->h_dest[4];
269 /* Clear the DMAC bytes that were mangled by the switch */
270 hdr->h_dest[3] = 0;
271 hdr->h_dest[4] = 0;
272 } else if (is_meta) {
273 sja1105_meta_unpack(skb, &meta);
274 source_port = meta.source_port;
275 switch_id = meta.switch_id;
276 } else {
277 return NULL;
278 }
279
280 skb->dev = dsa_master_find_slave(netdev, switch_id, source_port);
281 if (!skb->dev) {
282 netdev_warn(netdev, "Couldn't decode source port\n");
283 return NULL;
284 }
285
286 /* Delete/overwrite fake VLAN header, DSA expects to not find
287 * it there, see dsa_switch_rcv: skb_push(skb, ETH_HLEN).
288 */
289 if (is_tagged)
290 skb = dsa_8021q_remove_header(skb);
291
292 return sja1105_rcv_meta_state_machine(skb, &meta, is_link_local,
293 is_meta);
294 }
295
296 static struct dsa_device_ops sja1105_netdev_ops = {
297 .name = "sja1105",
298 .proto = DSA_TAG_PROTO_SJA1105,
299 .xmit = sja1105_xmit,
300 .rcv = sja1105_rcv,
301 .filter = sja1105_filter,
302 .overhead = VLAN_HLEN,
303 };
304
305 MODULE_LICENSE("GPL v2");
306 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_SJA1105);
307
308 module_dsa_tag_driver(sja1105_netdev_ops);
309