[PATCH net-next v6 3/9] net: add IEEE 802.1q specific helpers
From: Oleksij Rempel
Date: Wed Apr 10 2024 - 04:08:21 EST
IEEE 802.1q specification provides recommendation and examples which can
be used as good default values for different drivers.
This patch implements mapping examples documented in IEEE 802.1Q-2022 in
Annex I "I.3 Traffic type to traffic class mapping" and IETF DSCP naming
and mapping DSCP to Traffic Type inspired by RFC8325.
This helpers will be used in followup patches for dsa/microchip DCB
implementation.
Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
---
changes v6:
- do not set default n for NET_IEEE8021Q_HELPERS
- protect against accessing outside of the arrays in the
ieee8021q_tt_to_tc()
- use u8 for dscp instead of int
changes v4:
- use -EOPNOTSUPP instead of -ENOTSUP
- ieee8021q_tt_to_tc() return error if requested not supported amount
of queues
changes v2:
- properly export symbols with EXPORT_SYMBOL_GPL()
- return error if NET_IEEE8021Q_HELPERS is not enabled
---
include/net/dscp.h | 76 +++++++++++++
include/net/ieee8021q.h | 55 +++++++++
net/Kconfig | 3 +
net/core/Makefile | 1 +
net/core/ieee8021q_helpers.c | 208 +++++++++++++++++++++++++++++++++++
5 files changed, 343 insertions(+)
create mode 100644 include/net/dscp.h
create mode 100644 include/net/ieee8021q.h
create mode 100644 net/core/ieee8021q_helpers.c
diff --git a/include/net/dscp.h b/include/net/dscp.h
new file mode 100644
index 0000000000000..ba40540868c9c
--- /dev/null
+++ b/include/net/dscp.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2024 Pengutronix, Oleksij Rempel <kernel@xxxxxxxxxxxxxx> */
+
+#ifndef __DSCP_H__
+#define __DSCP_H__
+
+/*
+ * DSCP Pools and Codepoint Space Division:
+ *
+ * The Differentiated Services (Diffserv) architecture defines a method for
+ * classifying and managing network traffic using the DS field in IPv4 and IPv6
+ * packet headers. This field can carry one of 64 distinct DSCP (Differentiated
+ * Services Code Point) values, which are divided into three pools based on
+ * their Least Significant Bits (LSB) patterns and intended usage. Each pool has
+ * a specific registration procedure for assigning DSCP values:
+ *
+ * Pool 1 (Standards Action Pool):
+ * - Codepoint Space: xxxxx0
+ * This pool includes DSCP values ending in '0' (binary), allocated via
+ * Standards Action. It is intended for globally recognized traffic classes,
+ * ensuring interoperability across the internet. This pool encompasses
+ * well-known DSCP values such as CS0-CS7, AFxx, EF, and VOICE-ADMIT.
+ *
+ * Pool 2 (Experimental/Local Use Pool):
+ * - Codepoint Space: xxxx11
+ * Reserved for DSCP values ending in '11' (binary), this pool is designated
+ * for Experimental or Local Use. It allows for private or temporary traffic
+ * marking schemes not intended for standardized global use, facilitating
+ * testing and network-specific configurations without impacting
+ * interoperability.
+ *
+ * Pool 3 (Preferential Standardization Pool):
+ * - Codepoint Space: xxxx01
+ * Initially reserved for experimental or local use, this pool now serves as
+ * a secondary standardization resource should Pool 1 become exhausted. DSCP
+ * values ending in '01' (binary) are assigned via Standards Action, with a
+ * focus on adopting new, standardized traffic classes as the need arises.
+ *
+ * For pool updates see:
+ * https://www.iana.org/assignments/dscp-registry/dscp-registry.xhtml
+ */
+
+/* Pool 1: Standardized DSCP values as per [RFC8126] */
+#define DSCP_CS0 0 /* 000000, [RFC2474] */
+/* CS0 is some times called default (DF) */
+#define DSCP_DF 0 /* 000000, [RFC2474] */
+#define DSCP_CS1 8 /* 001000, [RFC2474] */
+#define DSCP_CS2 16 /* 010000, [RFC2474] */
+#define DSCP_CS3 24 /* 011000, [RFC2474] */
+#define DSCP_CS4 32 /* 100000, [RFC2474] */
+#define DSCP_CS5 40 /* 101000, [RFC2474] */
+#define DSCP_CS6 48 /* 110000, [RFC2474] */
+#define DSCP_CS7 56 /* 111000, [RFC2474] */
+#define DSCP_AF11 10 /* 001010, [RFC2597] */
+#define DSCP_AF12 12 /* 001100, [RFC2597] */
+#define DSCP_AF13 14 /* 001110, [RFC2597] */
+#define DSCP_AF21 18 /* 010010, [RFC2597] */
+#define DSCP_AF22 20 /* 010100, [RFC2597] */
+#define DSCP_AF23 22 /* 010110, [RFC2597] */
+#define DSCP_AF31 26 /* 011010, [RFC2597] */
+#define DSCP_AF32 28 /* 011100, [RFC2597] */
+#define DSCP_AF33 30 /* 011110, [RFC2597] */
+#define DSCP_AF41 34 /* 100010, [RFC2597] */
+#define DSCP_AF42 36 /* 100100, [RFC2597] */
+#define DSCP_AF43 38 /* 100110, [RFC2597] */
+#define DSCP_EF 46 /* 101110, [RFC3246] */
+#define DSCP_VOICE_ADMIT 44 /* 101100, [RFC5865] */
+
+/* Pool 3: Standardized assignments, previously available for experimental/local
+ * use
+ */
+#define DSCP_LE 1 /* 000001, [RFC8622] */
+
+#define DSCP_MAX 64
+
+#endif /* __DSCP_H__ */
diff --git a/include/net/ieee8021q.h b/include/net/ieee8021q.h
new file mode 100644
index 0000000000000..3bec7ec951362
--- /dev/null
+++ b/include/net/ieee8021q.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2024 Pengutronix, Oleksij Rempel <kernel@xxxxxxxxxxxxxx> */
+
+#ifndef _NET_IEEE8021Q_H
+#define _NET_IEEE8021Q_H
+
+#include <linux/errno.h>
+
+/**
+ * enum ieee8021q_traffic_type - 802.1Q traffic type priority values (802.1Q-2022)
+ *
+ * @IEEE8021Q_TT_BK: Background
+ * @IEEE8021Q_TT_BE: Best Effort (default). According to 802.1Q-2022, BE is 0
+ * but has higher priority than BK which is 1.
+ * @IEEE8021Q_TT_EE: Excellent Effort
+ * @IEEE8021Q_TT_CA: Critical Applications
+ * @IEEE8021Q_TT_VI: Video, < 100 ms latency and jitter
+ * @IEEE8021Q_TT_VO: Voice, < 10 ms latency and jitter
+ * @IEEE8021Q_TT_IC: Internetwork Control
+ * @IEEE8021Q_TT_NC: Network Control
+ */
+enum ieee8021q_traffic_type {
+ 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,
+
+ IEEE8021Q_TT_MAX,
+};
+
+#define SIMPLE_IETF_DSCP_TO_IEEE8021Q_TT(dscp) ((dscp >> 3) & 0x7)
+
+#if IS_ENABLED(CONFIG_NET_IEEE8021Q_HELPERS)
+
+int ietf_dscp_to_ieee8021q_tt(u8 dscp);
+int ieee8021q_tt_to_tc(unsigned int tt, unsigned int num_queues);
+
+#else
+
+static inline int ietf_dscp_to_ieee8021q_tt(int dscp)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int ieee8021q_tt_to_tc(int tt, int num_queues)
+{
+ return -EOPNOTSUPP;
+}
+
+#endif
+#endif /* _NET_IEEE8021Q_H */
diff --git a/net/Kconfig b/net/Kconfig
index d5ab791f7afa2..f0a8692496ffa 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -452,6 +452,9 @@ config GRO_CELLS
config SOCK_VALIDATE_XMIT
bool
+config NET_IEEE8021Q_HELPERS
+ bool
+
config NET_SELFTESTS
def_tristate PHYLIB
depends on PHYLIB && INET
diff --git a/net/core/Makefile b/net/core/Makefile
index 21d6fbc7e884c..62be9aef25285 100644
--- a/net/core/Makefile
+++ b/net/core/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_NETPOLL) += netpoll.o
obj-$(CONFIG_FIB_RULES) += fib_rules.o
obj-$(CONFIG_TRACEPOINTS) += net-traces.o
obj-$(CONFIG_NET_DROP_MONITOR) += drop_monitor.o
+obj-$(CONFIG_NET_IEEE8021Q_HELPERS) += ieee8021q_helpers.o
obj-$(CONFIG_NET_SELFTESTS) += selftests.o
obj-$(CONFIG_NETWORK_PHY_TIMESTAMPING) += timestamping.o
obj-$(CONFIG_NET_PTP_CLASSIFY) += ptp_classifier.o
diff --git a/net/core/ieee8021q_helpers.c b/net/core/ieee8021q_helpers.c
new file mode 100644
index 0000000000000..74b42334746da
--- /dev/null
+++ b/net/core/ieee8021q_helpers.c
@@ -0,0 +1,208 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2024 Pengutronix, Oleksij Rempel <kernel@xxxxxxxxxxxxxx>
+
+#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 switch. 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 -EINVAL if
+ * the number of queues is not supported. -EINVAL is used to differentiate from
+ * -EOPNOTSUPP which is used to indicate that this library function is not
+ * compiled in.
+ */
+int ieee8021q_tt_to_tc(unsigned int tt, unsigned int num_queues)
+{
+ if (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:
+ case DSCP_AF11:
+ case DSCP_AF12:
+ case DSCP_AF13:
+ return IEEE8021Q_TT_BE;
+ 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);
--
2.39.2