1// SPDX-License-Identifier: GPL-2.0
2// Copyright (c) 2024 Pengutronix, Oleksij Rempel <kernel@pengutronix.de>
3
4#include <linux/array_size.h>
5#include <linux/printk.h>
6#include <linux/types.h>
7#include <net/dscp.h>
8#include <net/ieee8021q.h>
9
10/* verify that table covers all 8 traffic types */
11#define TT_MAP_SIZE_OK(tbl) \
12 compiletime_assert(ARRAY_SIZE(tbl) == IEEE8021Q_TT_MAX, \
13 #tbl " size mismatch")
14
15/* The following arrays map Traffic Types (TT) to traffic classes (TC) for
16 * different number of queues as shown in the example provided by
17 * IEEE 802.1Q-2022 in Annex I "I.3 Traffic type to traffic class mapping" and
18 * Table I-1 "Traffic type to traffic class mapping".
19 */
20static const u8 ieee8021q_8queue_tt_tc_map[] = {
21 [IEEE8021Q_TT_BK] = 0,
22 [IEEE8021Q_TT_BE] = 1,
23 [IEEE8021Q_TT_EE] = 2,
24 [IEEE8021Q_TT_CA] = 3,
25 [IEEE8021Q_TT_VI] = 4,
26 [IEEE8021Q_TT_VO] = 5,
27 [IEEE8021Q_TT_IC] = 6,
28 [IEEE8021Q_TT_NC] = 7,
29};
30
31static const u8 ieee8021q_7queue_tt_tc_map[] = {
32 [IEEE8021Q_TT_BK] = 0,
33 [IEEE8021Q_TT_BE] = 1,
34 [IEEE8021Q_TT_EE] = 2,
35 [IEEE8021Q_TT_CA] = 3,
36 [IEEE8021Q_TT_VI] = 4, [IEEE8021Q_TT_VO] = 4,
37 [IEEE8021Q_TT_IC] = 5,
38 [IEEE8021Q_TT_NC] = 6,
39};
40
41static const u8 ieee8021q_6queue_tt_tc_map[] = {
42 [IEEE8021Q_TT_BK] = 0,
43 [IEEE8021Q_TT_BE] = 1,
44 [IEEE8021Q_TT_EE] = 2, [IEEE8021Q_TT_CA] = 2,
45 [IEEE8021Q_TT_VI] = 3, [IEEE8021Q_TT_VO] = 3,
46 [IEEE8021Q_TT_IC] = 4,
47 [IEEE8021Q_TT_NC] = 5,
48};
49
50static const u8 ieee8021q_5queue_tt_tc_map[] = {
51 [IEEE8021Q_TT_BK] = 0, [IEEE8021Q_TT_BE] = 0,
52 [IEEE8021Q_TT_EE] = 1, [IEEE8021Q_TT_CA] = 1,
53 [IEEE8021Q_TT_VI] = 2, [IEEE8021Q_TT_VO] = 2,
54 [IEEE8021Q_TT_IC] = 3,
55 [IEEE8021Q_TT_NC] = 4,
56};
57
58static const u8 ieee8021q_4queue_tt_tc_map[] = {
59 [IEEE8021Q_TT_BK] = 0, [IEEE8021Q_TT_BE] = 0,
60 [IEEE8021Q_TT_EE] = 1, [IEEE8021Q_TT_CA] = 1,
61 [IEEE8021Q_TT_VI] = 2, [IEEE8021Q_TT_VO] = 2,
62 [IEEE8021Q_TT_IC] = 3, [IEEE8021Q_TT_NC] = 3,
63};
64
65static const u8 ieee8021q_3queue_tt_tc_map[] = {
66 [IEEE8021Q_TT_BK] = 0, [IEEE8021Q_TT_BE] = 0,
67 [IEEE8021Q_TT_EE] = 0, [IEEE8021Q_TT_CA] = 0,
68 [IEEE8021Q_TT_VI] = 1, [IEEE8021Q_TT_VO] = 1,
69 [IEEE8021Q_TT_IC] = 2, [IEEE8021Q_TT_NC] = 2,
70};
71
72static const u8 ieee8021q_2queue_tt_tc_map[] = {
73 [IEEE8021Q_TT_BK] = 0, [IEEE8021Q_TT_BE] = 0,
74 [IEEE8021Q_TT_EE] = 0, [IEEE8021Q_TT_CA] = 0,
75 [IEEE8021Q_TT_VI] = 1, [IEEE8021Q_TT_VO] = 1,
76 [IEEE8021Q_TT_IC] = 1, [IEEE8021Q_TT_NC] = 1,
77};
78
79static const u8 ieee8021q_1queue_tt_tc_map[] = {
80 [IEEE8021Q_TT_BK] = 0, [IEEE8021Q_TT_BE] = 0,
81 [IEEE8021Q_TT_EE] = 0, [IEEE8021Q_TT_CA] = 0,
82 [IEEE8021Q_TT_VI] = 0, [IEEE8021Q_TT_VO] = 0,
83 [IEEE8021Q_TT_IC] = 0, [IEEE8021Q_TT_NC] = 0,
84};
85
86/**
87 * ieee8021q_tt_to_tc - Map IEEE 802.1Q Traffic Type to Traffic Class
88 * @tt: IEEE 802.1Q Traffic Type
89 * @num_queues: Number of queues
90 *
91 * This function maps an IEEE 802.1Q Traffic Type to a Traffic Class (TC) based
92 * on the number of queues configured on the NIC. The mapping is based on the
93 * example provided by IEEE 802.1Q-2022 in Annex I "I.3 Traffic type to traffic
94 * class mapping" and Table I-1 "Traffic type to traffic class mapping".
95 *
96 * Return: Traffic Class corresponding to the given Traffic Type or negative
97 * value in case of error.
98 */
99int ieee8021q_tt_to_tc(enum ieee8021q_traffic_type tt, unsigned int num_queues)
100{
101 if (tt < 0 || tt >= IEEE8021Q_TT_MAX) {
102 pr_err("Requested Traffic Type (%d) is out of range (%d)\n", tt,
103 IEEE8021Q_TT_MAX);
104 return -EINVAL;
105 }
106
107 switch (num_queues) {
108 case 8:
109 TT_MAP_SIZE_OK(ieee8021q_8queue_tt_tc_map);
110 return ieee8021q_8queue_tt_tc_map[tt];
111 case 7:
112 TT_MAP_SIZE_OK(ieee8021q_7queue_tt_tc_map);
113 return ieee8021q_7queue_tt_tc_map[tt];
114 case 6:
115 TT_MAP_SIZE_OK(ieee8021q_6queue_tt_tc_map);
116 return ieee8021q_6queue_tt_tc_map[tt];
117 case 5:
118 TT_MAP_SIZE_OK(ieee8021q_5queue_tt_tc_map);
119 return ieee8021q_5queue_tt_tc_map[tt];
120 case 4:
121 TT_MAP_SIZE_OK(ieee8021q_4queue_tt_tc_map);
122 return ieee8021q_4queue_tt_tc_map[tt];
123 case 3:
124 TT_MAP_SIZE_OK(ieee8021q_3queue_tt_tc_map);
125 return ieee8021q_3queue_tt_tc_map[tt];
126 case 2:
127 TT_MAP_SIZE_OK(ieee8021q_2queue_tt_tc_map);
128 return ieee8021q_2queue_tt_tc_map[tt];
129 case 1:
130 TT_MAP_SIZE_OK(ieee8021q_1queue_tt_tc_map);
131 return ieee8021q_1queue_tt_tc_map[tt];
132 }
133
134 pr_err("Invalid number of queues %d\n", num_queues);
135
136 return -EINVAL;
137}
138EXPORT_SYMBOL_GPL(ieee8021q_tt_to_tc);
139
140/**
141 * ietf_dscp_to_ieee8021q_tt - Map IETF DSCP to IEEE 802.1Q Traffic Type
142 * @dscp: IETF DSCP value
143 *
144 * This function maps an IETF DSCP value to an IEEE 802.1Q Traffic Type (TT).
145 * Since there is no corresponding mapping between DSCP and IEEE 802.1Q Traffic
146 * Type, this function is inspired by the RFC8325 documentation which describe
147 * the mapping between DSCP and 802.11 User Priority (UP) values.
148 *
149 * Return: IEEE 802.1Q Traffic Type corresponding to the given DSCP value
150 */
151int ietf_dscp_to_ieee8021q_tt(u8 dscp)
152{
153 switch (dscp) {
154 case DSCP_CS0:
155 /* Comment from RFC8325:
156 * [RFC4594], Section 4.8, recommends High-Throughput Data be marked
157 * AF1x (that is, AF11, AF12, and AF13, according to the rules defined
158 * in [RFC2475]).
159 *
160 * By default (as described in Section 2.3), High-Throughput Data will
161 * map to UP 1 and, thus, to the Background Access Category (AC_BK),
162 * which is contrary to the intent expressed in [RFC4594].
163
164 * Unfortunately, there really is no corresponding fit for the High-
165 * Throughput Data service class within the constrained 4 Access
166 * Category [IEEE.802.11-2016] model. If the High-Throughput Data
167 * service class is assigned to the Best Effort Access Category (AC_BE),
168 * then it would contend with Low-Latency Data (while [RFC4594]
169 * recommends a distinction in servicing between these service classes)
170 * as well as with the default service class; alternatively, if it is
171 * assigned to the Background Access Category (AC_BK), then it would
172 * receive a less-then-best-effort service and contend with Low-Priority
173 * Data (as discussed in Section 4.2.10).
174 *
175 * As such, since there is no directly corresponding fit for the High-
176 * Throughout Data service class within the [IEEE.802.11-2016] model, it
177 * is generally RECOMMENDED to map High-Throughput Data to UP 0, thereby
178 * admitting it to the Best Effort Access Category (AC_BE).
179 *
180 * Note: The above text is from RFC8325 which is describing the mapping
181 * between DSCP and 802.11 User Priority (UP) values. The mapping
182 * between UP and IEEE 802.1Q Traffic Type is not defined in the RFC but
183 * the 802.11 AC_BK and AC_BE are closely related to the IEEE 802.1Q
184 * Traffic Types BE and BK.
185 */
186 case DSCP_AF11:
187 case DSCP_AF12:
188 case DSCP_AF13:
189 return IEEE8021Q_TT_BE;
190 /* Comment from RFC8325:
191 * RFC3662 and RFC4594 both recommend Low-Priority Data be marked
192 * with DSCP CS1. The Low-Priority Data service class loosely
193 * corresponds to the [IEEE.802.11-2016] Background Access Category
194 */
195 case DSCP_CS1:
196 return IEEE8021Q_TT_BK;
197 case DSCP_CS2:
198 case DSCP_AF21:
199 case DSCP_AF22:
200 case DSCP_AF23:
201 return IEEE8021Q_TT_EE;
202 case DSCP_CS3:
203 case DSCP_AF31:
204 case DSCP_AF32:
205 case DSCP_AF33:
206 return IEEE8021Q_TT_CA;
207 case DSCP_CS4:
208 case DSCP_AF41:
209 case DSCP_AF42:
210 case DSCP_AF43:
211 return IEEE8021Q_TT_VI;
212 case DSCP_CS5:
213 case DSCP_EF:
214 case DSCP_VOICE_ADMIT:
215 return IEEE8021Q_TT_VO;
216 case DSCP_CS6:
217 return IEEE8021Q_TT_IC;
218 case DSCP_CS7:
219 return IEEE8021Q_TT_NC;
220 }
221
222 return SIMPLE_IETF_DSCP_TO_IEEE8021Q_TT(dscp);
223}
224EXPORT_SYMBOL_GPL(ietf_dscp_to_ieee8021q_tt);
225

source code of linux/net/core/ieee8021q_helpers.c