net: add IEEE 802.1q specific helpers

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@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 133 insertions, 0 deletions

diff --git a/include/net/dscp.h b/include/net/dscp.h
new file mode 100644
index 00000000000000..ba40540868c9c2
--- /dev/null
+++ b/include/net/dscp.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2024 Pengutronix, Oleksij Rempel <kernel@pengutronix.de> */
+
+#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 00000000000000..8bfe903dd3d00f
--- /dev/null
+++ b/include/net/ieee8021q.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2024 Pengutronix, Oleksij Rempel <kernel@pengutronix.de> */
+
+#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,
+
+	/* private: */
+	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(enum ieee8021q_traffic_type tt, unsigned int num_queues);
+
+#else
+
+static inline int ietf_dscp_to_ieee8021q_tt(u8 dscp)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int ieee8021q_tt_to_tc(enum ieee8021q_traffic_type tt,
+				     unsigned int num_queues)
+{
+	return -EOPNOTSUPP;
+}
+
+#endif
+#endif /* _NET_IEEE8021Q_H */