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The ocelot tagger is a hot mess currently, it relies on memory initialized by the attached driver for basic frame transmission. This is against all that DSA tagging protocols stand for, which is that the transmission and reception of a DSA-tagged frame, the data path, should be independent from the switch control path, because the tag protocol is in principle hot-pluggable and reusable across switches (even if in practice it wasn't until very recently). But if another driver like dsa_loop wants to make use of tag_ocelot, it couldn't. This was done to have common code between Felix and Ocelot, which have one bit difference in the frame header format. Quoting from commit67c2404922("net: dsa: felix: create a template for the DSA tags on xmit"): Other alternatives have been analyzed, such as: - Create a separate tag_seville.c: too much code duplication for just 1 bit field difference. - Create a separate DSA_TAG_PROTO_SEVILLE under tag_ocelot.c, just like tag_brcm.c, which would have a separate .xmit function. Again, too much code duplication for just 1 bit field difference. - Allocate the template from the init function of the tag_ocelot.c module, instead of from the driver: couldn't figure out a method of accessing the correct port template corresponding to the correct tagger in the .xmit function. The really interesting part is that Seville should have had its own tagging protocol defined - it is not compatible on the wire with Ocelot, even for that single bit. In principle, a packet generated by DSA_TAG_PROTO_OCELOT when booted on NXP LS1028A would look in a certain way, but when booted on NXP T1040 it would look differently. The reverse is also true: a packet generated by a Seville switch would be interpreted incorrectly by Wireshark if it was told it was generated by an Ocelot switch. Actually things are a bit more nuanced. If we concentrate only on the DSA tag, what I said above is true, but Ocelot/Seville also support an optional DSA tag prefix, which can be short or long, and it is possible to distinguish the two taggers based on an integer constant put in that prefix. Nonetheless, creating a separate tagger is still justified, since the tag prefix is optional, and without it, there is again no way to distinguish. Claiming backwards binary compatibility is a bit more tough, since I've already changed the format of tag_ocelot once, in commit5124197ce5("net: dsa: tag_ocelot: use a short prefix on both ingress and egress"). Therefore I am not very concerned with treating this as a bugfix and backporting it to stable kernels (which would be another mess due to the fact that there would be lots of conflicts with the other DSA_TAG_PROTO* definitions). It's just simpler to say that the string values of the taggers have ABI value starting with kernel 5.12, which will be when the changing of tag protocol via /sys/class/net/<dsa-master>/dsa/tagging goes live. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
58 lines
1.7 KiB
C
58 lines
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* Copyright 2019 NXP Semiconductors
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*/
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#ifndef _MSCC_FELIX_H
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#define _MSCC_FELIX_H
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#define ocelot_to_felix(o) container_of((o), struct felix, ocelot)
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/* Platform-specific information */
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struct felix_info {
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const struct resource *target_io_res;
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const struct resource *port_io_res;
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const struct resource *imdio_res;
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const struct reg_field *regfields;
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const u32 *const *map;
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const struct ocelot_ops *ops;
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int num_mact_rows;
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const struct ocelot_stat_layout *stats_layout;
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unsigned int num_stats;
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int num_ports;
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int num_tx_queues;
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struct vcap_props *vcap;
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int switch_pci_bar;
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int imdio_pci_bar;
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const struct ptp_clock_info *ptp_caps;
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int (*mdio_bus_alloc)(struct ocelot *ocelot);
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void (*mdio_bus_free)(struct ocelot *ocelot);
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void (*phylink_validate)(struct ocelot *ocelot, int port,
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unsigned long *supported,
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struct phylink_link_state *state);
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int (*prevalidate_phy_mode)(struct ocelot *ocelot, int port,
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phy_interface_t phy_mode);
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int (*port_setup_tc)(struct dsa_switch *ds, int port,
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enum tc_setup_type type, void *type_data);
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void (*port_sched_speed_set)(struct ocelot *ocelot, int port,
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u32 speed);
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};
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extern const struct dsa_switch_ops felix_switch_ops;
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/* DSA glue / front-end for struct ocelot */
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struct felix {
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struct dsa_switch *ds;
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const struct felix_info *info;
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struct ocelot ocelot;
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struct mii_bus *imdio;
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struct lynx_pcs **pcs;
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resource_size_t switch_base;
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resource_size_t imdio_base;
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struct dsa_8021q_context *dsa_8021q_ctx;
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enum dsa_tag_protocol tag_proto;
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};
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struct net_device *felix_port_to_netdev(struct ocelot *ocelot, int port);
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int felix_netdev_to_port(struct net_device *dev);
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#endif
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