// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2024 Pengutronix, Oleksij Rempel <[email protected]>
#include <linux/array_size.h>
#include <linux/printk.h>
#include <linux/types.h>
#include <net/dscp.h>
#include <net/ieee8021q.h>
/* The following arrays map Traffic Types (TT) to traffic classes (TC) for
* different number of queues as shown in the example provided by
* IEEE 802.1Q-2022 in Annex I "I.3 Traffic type to traffic class mapping" and
* Table I-1 "Traffic type to traffic class mapping".
*/
static const u8 ieee8021q_8queue_tt_tc_map[] = {
[IEEE8021Q_TT_BK] = 0,
[IEEE8021Q_TT_BE] = 1,
[IEEE8021Q_TT_EE] = 2,
[IEEE8021Q_TT_CA] = 3,
[IEEE8021Q_TT_VI] = 4,
[IEEE8021Q_TT_VO] = 5,
[IEEE8021Q_TT_IC] = 6,
[IEEE8021Q_TT_NC] = 7,
};
static const u8 ieee8021q_7queue_tt_tc_map[] = {
[IEEE8021Q_TT_BK] = 0,
[IEEE8021Q_TT_BE] = 1,
[IEEE8021Q_TT_EE] = 2,
[IEEE8021Q_TT_CA] = 3,
[IEEE8021Q_TT_VI] = 4, [IEEE8021Q_TT_VO] = 4,
[IEEE8021Q_TT_IC] = 5,
[IEEE8021Q_TT_NC] = 6,
};
static const u8 ieee8021q_6queue_tt_tc_map[] = {
[IEEE8021Q_TT_BK] = 0,
[IEEE8021Q_TT_BE] = 1,
[IEEE8021Q_TT_EE] = 2, [IEEE8021Q_TT_CA] = 2,
[IEEE8021Q_TT_VI] = 3, [IEEE8021Q_TT_VO] = 3,
[IEEE8021Q_TT_IC] = 4,
[IEEE8021Q_TT_NC] = 5,
};
static const u8 ieee8021q_5queue_tt_tc_map[] = {
[IEEE8021Q_TT_BK] = 0, [IEEE8021Q_TT_BE] = 0,
[IEEE8021Q_TT_EE] = 1, [IEEE8021Q_TT_CA] = 1,
[IEEE8021Q_TT_VI] = 2, [IEEE8021Q_TT_VO] = 2,
[IEEE8021Q_TT_IC] = 3,
[IEEE8021Q_TT_NC] = 4,
};
static const u8 ieee8021q_4queue_tt_tc_map[] = {
[IEEE8021Q_TT_BK] = 0, [IEEE8021Q_TT_BE] = 0,
[IEEE8021Q_TT_EE] = 1, [IEEE8021Q_TT_CA] = 1,
[IEEE8021Q_TT_VI] = 2, [IEEE8021Q_TT_VO] = 2,
[IEEE8021Q_TT_IC] = 3, [IEEE8021Q_TT_NC] = 3,
};
static const u8 ieee8021q_3queue_tt_tc_map[] = {
[IEEE8021Q_TT_BK] = 0, [IEEE8021Q_TT_BE] = 0,
[IEEE8021Q_TT_EE] = 0, [IEEE8021Q_TT_CA] = 0,
[IEEE8021Q_TT_VI] = 1, [IEEE8021Q_TT_VO] = 1,
[IEEE8021Q_TT_IC] = 2, [IEEE8021Q_TT_NC] = 2,
};
static const u8 ieee8021q_2queue_tt_tc_map[] = {
[IEEE8021Q_TT_BK] = 0, [IEEE8021Q_TT_BE] = 0,
[IEEE8021Q_TT_EE] = 0, [IEEE8021Q_TT_CA] = 0,
[IEEE8021Q_TT_VI] = 1, [IEEE8021Q_TT_VO] = 1,
[IEEE8021Q_TT_IC] = 1, [IEEE8021Q_TT_NC] = 1,
};
static const u8 ieee8021q_1queue_tt_tc_map[] = {
[IEEE8021Q_TT_BK] = 0, [IEEE8021Q_TT_BE] = 0,
[IEEE8021Q_TT_EE] = 0, [IEEE8021Q_TT_CA] = 0,
[IEEE8021Q_TT_VI] = 0, [IEEE8021Q_TT_VO] = 0,
[IEEE8021Q_TT_IC] = 0, [IEEE8021Q_TT_NC] = 0,
};
/**
* ieee8021q_tt_to_tc - Map IEEE 802.1Q Traffic Type to Traffic Class
* @tt: IEEE 802.1Q Traffic Type
* @num_queues: Number of queues
*
* This function maps an IEEE 802.1Q Traffic Type to a Traffic Class (TC) based
* on the number of queues configured on the NIC. The mapping is based on the
* example provided by IEEE 802.1Q-2022 in Annex I "I.3 Traffic type to traffic
* class mapping" and Table I-1 "Traffic type to traffic class mapping".
*
* Return: Traffic Class corresponding to the given Traffic Type or negative
* value in case of error.
*/
int ieee8021q_tt_to_tc(enum ieee8021q_traffic_type tt, unsigned int num_queues)
{
if (tt < 0 || tt >= IEEE8021Q_TT_MAX) {
pr_err("Requested Traffic Type (%d) is out of range (%d)\n", tt,
IEEE8021Q_TT_MAX);
return -EINVAL;
}
switch (num_queues) {
case 8:
compiletime_assert(ARRAY_SIZE(ieee8021q_8queue_tt_tc_map) !=
IEEE8021Q_TT_MAX - 1,
"ieee8021q_8queue_tt_tc_map != max - 1");
return ieee8021q_8queue_tt_tc_map[tt];
case 7:
compiletime_assert(ARRAY_SIZE(ieee8021q_7queue_tt_tc_map) !=
IEEE8021Q_TT_MAX - 1,
"ieee8021q_7queue_tt_tc_map != max - 1");
return ieee8021q_7queue_tt_tc_map[tt];
case 6:
compiletime_assert(ARRAY_SIZE(ieee8021q_6queue_tt_tc_map) !=
IEEE8021Q_TT_MAX - 1,
"ieee8021q_6queue_tt_tc_map != max - 1");
return ieee8021q_6queue_tt_tc_map[tt];
case 5:
compiletime_assert(ARRAY_SIZE(ieee8021q_5queue_tt_tc_map) !=
IEEE8021Q_TT_MAX - 1,
"ieee8021q_5queue_tt_tc_map != max - 1");
return ieee8021q_5queue_tt_tc_map[tt];
case 4:
compiletime_assert(ARRAY_SIZE(ieee8021q_4queue_tt_tc_map) !=
IEEE8021Q_TT_MAX - 1,
"ieee8021q_4queue_tt_tc_map != max - 1");
return ieee8021q_4queue_tt_tc_map[tt];
case 3:
compiletime_assert(ARRAY_SIZE(ieee8021q_3queue_tt_tc_map) !=
IEEE8021Q_TT_MAX - 1,
"ieee8021q_3queue_tt_tc_map != max - 1");
return ieee8021q_3queue_tt_tc_map[tt];
case 2:
compiletime_assert(ARRAY_SIZE(ieee8021q_2queue_tt_tc_map) !=
IEEE8021Q_TT_MAX - 1,
"ieee8021q_2queue_tt_tc_map != max - 1");
return ieee8021q_2queue_tt_tc_map[tt];
case 1:
compiletime_assert(ARRAY_SIZE(ieee8021q_1queue_tt_tc_map) !=
IEEE8021Q_TT_MAX - 1,
"ieee8021q_1queue_tt_tc_map != max - 1");
return ieee8021q_1queue_tt_tc_map[tt];
}
pr_err("Invalid number of queues %d\n", num_queues);
return -EINVAL;
}
EXPORT_SYMBOL_GPL(ieee8021q_tt_to_tc);
/**
* ietf_dscp_to_ieee8021q_tt - Map IETF DSCP to IEEE 802.1Q Traffic Type
* @dscp: IETF DSCP value
*
* This function maps an IETF DSCP value to an IEEE 802.1Q Traffic Type (TT).
* Since there is no corresponding mapping between DSCP and IEEE 802.1Q Traffic
* Type, this function is inspired by the RFC8325 documentation which describe
* the mapping between DSCP and 802.11 User Priority (UP) values.
*
* Return: IEEE 802.1Q Traffic Type corresponding to the given DSCP value
*/
int ietf_dscp_to_ieee8021q_tt(u8 dscp)
{
switch (dscp) {
case DSCP_CS0:
/* Comment from RFC8325:
* [RFC4594], Section 4.8, recommends High-Throughput Data be marked
* AF1x (that is, AF11, AF12, and AF13, according to the rules defined
* in [RFC2475]).
*
* By default (as described in Section 2.3), High-Throughput Data will
* map to UP 1 and, thus, to the Background Access Category (AC_BK),
* which is contrary to the intent expressed in [RFC4594].
* Unfortunately, there really is no corresponding fit for the High-
* Throughput Data service class within the constrained 4 Access
* Category [IEEE.802.11-2016] model. If the High-Throughput Data
* service class is assigned to the Best Effort Access Category (AC_BE),
* then it would contend with Low-Latency Data (while [RFC4594]
* recommends a distinction in servicing between these service classes)
* as well as with the default service class; alternatively, if it is
* assigned to the Background Access Category (AC_BK), then it would
* receive a less-then-best-effort service and contend with Low-Priority
* Data (as discussed in Section 4.2.10).
*
* As such, since there is no directly corresponding fit for the High-
* Throughout Data service class within the [IEEE.802.11-2016] model, it
* is generally RECOMMENDED to map High-Throughput Data to UP 0, thereby
* admitting it to the Best Effort Access Category (AC_BE).
*
* Note: The above text is from RFC8325 which is describing the mapping
* between DSCP and 802.11 User Priority (UP) values. The mapping
* between UP and IEEE 802.1Q Traffic Type is not defined in the RFC but
* the 802.11 AC_BK and AC_BE are closely related to the IEEE 802.1Q
* Traffic Types BE and BK.
*/
case DSCP_AF11:
case DSCP_AF12:
case DSCP_AF13:
return IEEE8021Q_TT_BE;
/* Comment from RFC8325:
* RFC3662 and RFC4594 both recommend Low-Priority Data be marked
* with DSCP CS1. The Low-Priority Data service class loosely
* corresponds to the [IEEE.802.11-2016] Background Access Category
*/
case DSCP_CS1:
return IEEE8021Q_TT_BK;
case DSCP_CS2:
case DSCP_AF21:
case DSCP_AF22:
case DSCP_AF23:
return IEEE8021Q_TT_EE;
case DSCP_CS3:
case DSCP_AF31:
case DSCP_AF32:
case DSCP_AF33:
return IEEE8021Q_TT_CA;
case DSCP_CS4:
case DSCP_AF41:
case DSCP_AF42:
case DSCP_AF43:
return IEEE8021Q_TT_VI;
case DSCP_CS5:
case DSCP_EF:
case DSCP_VOICE_ADMIT:
return IEEE8021Q_TT_VO;
case DSCP_CS6:
return IEEE8021Q_TT_IC;
case DSCP_CS7:
return IEEE8021Q_TT_NC;
}
return SIMPLE_IETF_DSCP_TO_IEEE8021Q_TT(dscp);
}
EXPORT_SYMBOL_GPL(ietf_dscp_to_ieee8021q_tt);
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