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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright 2025-2026 NXP
4 */
5
6#include <linux/dsa/tag_netc.h>
7
8#include "tag.h"
9
10#define NETC_NAME "nxp_netc"
11
12/* Forward NXP switch tag */
13#define NETC_TAG_FORWARD 0
14
15/* To_Port NXP switch tag */
16#define NETC_TAG_TO_PORT 1
17/* SubType0: No request to perform timestamping */
18#define NETC_TAG_TP_SUBTYPE0 0
19
20/* To_Host NXP switch tag */
21#define NETC_TAG_TO_HOST 2
22/* SubType0: frames redirected or copied to CPU port */
23#define NETC_TAG_TH_SUBTYPE0 0
24/* SubType1: frames redirected or copied to CPU port with timestamp */
25#define NETC_TAG_TH_SUBTYPE1 1
26/* SubType2: Transmit timestamp response (two-step timestamping) */
27#define NETC_TAG_TH_SUBTYPE2 2
28
29/* NETC switch tag lengths */
30#define NETC_TAG_FORWARD_LEN 6
31#define NETC_TAG_TP_SUBTYPE0_LEN 6
32#define NETC_TAG_TH_SUBTYPE0_LEN 6
33#define NETC_TAG_TH_SUBTYPE1_LEN 14
34#define NETC_TAG_TH_SUBTYPE2_LEN 14
35#define NETC_TAG_CMN_LEN 5
36
37#define NETC_TAG_SUBTYPE GENMASK(3, 0)
38#define NETC_TAG_TYPE GENMASK(7, 4)
39#define NETC_TAG_QV BIT(0)
40#define NETC_TAG_IPV GENMASK(4, 2)
41#define NETC_TAG_SWITCH GENMASK(2, 0)
42#define NETC_TAG_PORT GENMASK(7, 3)
43
44struct netc_tag_cmn {
45 __be16 tpid;
46 u8 type;
47 u8 qos;
48 u8 switch_port;
49} __packed;
50
51static void netc_fill_common_tag(struct netc_tag_cmn *tag, u8 type,
52 u8 subtype, u8 sw_id, u8 port, u8 ipv)
53{
54 tag->tpid = htons(ETH_P_NXP_NETC);
55 tag->type = FIELD_PREP(NETC_TAG_TYPE, type) |
56 FIELD_PREP(NETC_TAG_SUBTYPE, subtype);
57 tag->qos = NETC_TAG_QV | FIELD_PREP(NETC_TAG_IPV, ipv);
58 tag->switch_port = FIELD_PREP(NETC_TAG_SWITCH, sw_id) |
59 FIELD_PREP(NETC_TAG_PORT, port);
60}
61
62static void *netc_fill_common_tp_tag(struct sk_buff *skb,
63 struct net_device *ndev,
64 u8 subtype, int tag_len)
65{
66 struct dsa_port *dp = dsa_user_to_port(ndev);
67 u16 queue = skb_get_queue_mapping(skb);
68 s8 ipv = netdev_txq_to_tc(ndev, queue);
69 void *tag;
70
71 if (unlikely(ipv < 0))
72 ipv = 0;
73
74 skb_push(skb, tag_len);
75 dsa_alloc_etype_header(skb, tag_len);
76
77 tag = dsa_etype_header_pos_tx(skb);
78 memset(tag + NETC_TAG_CMN_LEN, 0, tag_len - NETC_TAG_CMN_LEN);
79 /* As 'dsa,member' is a required property for NETC switch, the member
80 * is used to specify the switch ID (thus the hardware switch ID and
81 * the software switch ID are consistent), its range is 1 ~ 7. The
82 * NETC switch driver will check this value, and if it is invalid,
83 * the switch driver will fail the probe.
84 * In addition, according to the nxp,netc-switch.yaml doc, the port
85 * index will not be greater than 0xf.
86 */
87 netc_fill_common_tag(tag, NETC_TAG_TO_PORT, subtype,
88 dp->ds->index, dp->index, ipv);
89
90 return tag;
91}
92
93static void netc_fill_tp_tag_subtype0(struct sk_buff *skb,
94 struct net_device *ndev)
95{
96 netc_fill_common_tp_tag(skb, ndev, NETC_TAG_TP_SUBTYPE0,
97 NETC_TAG_TP_SUBTYPE0_LEN);
98}
99
100/* Currently only support To_Port tag, subtype 0 */
101static struct sk_buff *netc_xmit(struct sk_buff *skb,
102 struct net_device *ndev)
103{
104 netc_fill_tp_tag_subtype0(skb, ndev);
105
106 return skb;
107}
108
109static int netc_get_rx_tag_len(int type, int subtype)
110{
111 /* Only NETC_TAG_TO_HOST and NETC_TAG_FORWARD are expected in RX,
112 * NETC_TAG_TO_PORT is a TX switch tag that does not exist in RX.
113 */
114 if (type == NETC_TAG_TO_HOST) {
115 if (subtype == NETC_TAG_TH_SUBTYPE1)
116 return NETC_TAG_TH_SUBTYPE1_LEN;
117 else if (subtype == NETC_TAG_TH_SUBTYPE2)
118 return NETC_TAG_TH_SUBTYPE2_LEN;
119 else
120 return NETC_TAG_TH_SUBTYPE0_LEN;
121 }
122
123 return NETC_TAG_FORWARD_LEN;
124}
125
126static struct sk_buff *netc_rcv(struct sk_buff *skb,
127 struct net_device *ndev)
128{
129 struct netc_tag_cmn *tag_cmn;
130 int tag_len, sw_id, port;
131 int type, subtype;
132
133 if (unlikely(!pskb_may_pull(skb, NETC_TAG_MAX_LEN)))
134 goto err_free_skb;
135
136 tag_cmn = dsa_etype_header_pos_rx(skb);
137 if (ntohs(tag_cmn->tpid) != ETH_P_NXP_NETC) {
138 dev_warn_ratelimited(&ndev->dev, "Unknown TPID 0x%04x\n",
139 ntohs(tag_cmn->tpid));
140 goto err_free_skb;
141 }
142
143 if (tag_cmn->qos & NETC_TAG_QV)
144 skb->priority = FIELD_GET(NETC_TAG_IPV, tag_cmn->qos);
145
146 sw_id = FIELD_GET(NETC_TAG_SWITCH, tag_cmn->switch_port);
147 /* ENETC VEPA switch ID (0) is not supported yet */
148 if (!sw_id) {
149 dev_warn_ratelimited(&ndev->dev,
150 "VEPA switch ID is not supported yet\n");
151 goto err_free_skb;
152 }
153
154 port = FIELD_GET(NETC_TAG_PORT, tag_cmn->switch_port);
155 skb->dev = dsa_conduit_find_user(ndev, sw_id, port);
156 if (!skb->dev)
157 goto err_free_skb;
158
159 type = FIELD_GET(NETC_TAG_TYPE, tag_cmn->type);
160 subtype = FIELD_GET(NETC_TAG_SUBTYPE, tag_cmn->type);
161 if (type == NETC_TAG_FORWARD) {
162 dsa_default_offload_fwd_mark(skb);
163 } else if (type == NETC_TAG_TO_HOST) {
164 /* Currently only subtype0 supported */
165 if (subtype != NETC_TAG_TH_SUBTYPE0)
166 goto err_free_skb;
167 } else {
168 dev_warn_ratelimited(&ndev->dev,
169 "Unexpected tag type %d\n", type);
170 goto err_free_skb;
171 }
172
173 /* Remove Switch tag from the frame */
174 tag_len = netc_get_rx_tag_len(type, subtype);
175 skb_pull_rcsum(skb, tag_len);
176 dsa_strip_etype_header(skb, tag_len);
177
178 return skb;
179
180err_free_skb:
181 kfree_skb(skb);
182 return NULL;
183}
184
185static void netc_flow_dissect(const struct sk_buff *skb, __be16 *proto,
186 int *offset)
187{
188 struct netc_tag_cmn *tag_cmn = (struct netc_tag_cmn *)(skb->data - 2);
189 int subtype = FIELD_GET(NETC_TAG_SUBTYPE, tag_cmn->type);
190 int type = FIELD_GET(NETC_TAG_TYPE, tag_cmn->type);
191 int tag_len = netc_get_rx_tag_len(type, subtype);
192
193 /* The RX minimum frame length of the NETC switch port is 64 bytes,
194 * and the frame is received by the ENETC driver. From the hardware
195 * perspective, the receive buffer of RX BD is at least 128 bytes,
196 * so the switch tag header is guaranteed to be in the linear region
197 * of the skb.
198 */
199 *offset = tag_len;
200 *proto = ((__be16 *)skb->data)[(tag_len / 2) - 1];
201}
202
203static const struct dsa_device_ops netc_netdev_ops = {
204 .name = NETC_NAME,
205 .proto = DSA_TAG_PROTO_NETC,
206 .xmit = netc_xmit,
207 .rcv = netc_rcv,
208 .needed_headroom = NETC_TAG_MAX_LEN,
209 .flow_dissect = netc_flow_dissect,
210};
211
212MODULE_DESCRIPTION("DSA tag driver for NXP NETC switch family");
213MODULE_LICENSE("GPL");
214
215MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_NETC, NETC_NAME);
216module_dsa_tag_driver(netc_netdev_ops);