Subject: [PATCH net-next v9 0/4] net: dsa: initial support for MaxLinear MxL862xx switches

From: Daniel Golle <[email-masked]>
Date: Tue, 27 Jan 2026 21:37:40 +0000

This series adds very basic DSA support for the MaxLinear MxL86252
(5 PHY ports) and MxL86282 (8 PHY ports) switches.

MxL862xx integrates a firmware running on an embedded processor (running
Zephyr RTOS). Host interaction uses a simple netlink-like API transported
over MDIO/MMD.

This series includes only what's needed to pass traffic between user
ports and the CPU port: relayed MDIO to internal PHYs, basic port
enable/disable, and CPU-port special tagging.

Follow up series will bring bridge, VLAN, ... offloading, and support
for using a 802.1Q-based special tag instead of the proprietary 8-byte
tag.
---
basic DSA selftests were run, results:
 * no_forwarding.sh: all tests PASS
 * bridge_vlan_unaware.sh: all tests PASS
 * bridge_vlan_mcast.sh: all tests PASS
 * bridge_vlan_aware.sh: all tests PASS
 * local_termination.sh: all tests PASS or XFAIL, except for
TEST: VLAN over vlan_filtering=1 bridged port: Unicast IPv4 to unknown MAC address   [FAIL]
        reception succeeded, but should have failed
TEST: VLAN over vlan_filtering=1 bridged port: Unicast IPv4 to unknown MAC address, allmulti   [FAIL]
        reception succeeded, but should have failed

As obviously this is mostly testing the Linux software bridge at this point
so I didn't bother to run any of the FDB or MDB related tests.

Changes since v8:
1/4 dt-bindings: net: dsa: add MaxLinear MxL862xx
 * no changes
2/4 net: dsa: add tag format for MxL862xx switches
 * no changes
3/4 net: mdio: add unlocked mdiodev C45 bus accessors
 * no changes
4/4 net: dsa: add basic initial driver for MxL862xx switches
 * remove practically unused struct hw_info
 * lots of kerneldoc improvements in mxl862xx-api.h
 * drop .mac_select_pcs() stub
 * better handling for firmware error return value
 * apply reverse xmas tree in mxl862xx_api_wrap
 * guard headers with #ifdef macro
 * include net/dsa.h and linux/mdio.h in mxl862xx.h
 * call mxl862xx_port_fast_age() only once in .port_setup
 * don't create isolation bridges for unused ports
 * replace errornous cast with correct range of values denoting firmware errors

Changes since v7
1/4 dt-bindings: net: dsa: add MaxLinear MxL862xx
 * no changes
2/4 net: dsa: add tag format for MxL862xx switches
 * no changes
3/4 net: mdio: add unlocked mdiodev C45 bus accessors
 * no changes
4/4 net: dsa: add basic initial driver for MxL862xx switches
 * use little-endian in bridge_port_config API
 * remove duplciate assignment of br_port_cfg.bridge_port_id when setting
   up CPU port

Changes since v6
1/4 dt-bindings: net: dsa: add MaxLinear MxL862xx
 * no changes
2/4 net: dsa: add tag format for MxL862xx switches
 * no changes
3/4 net: mdio: add unlocked mdiodev C45 bus accessors
 * no changes
4/4 net: dsa: add basic initial driver for MxL862xx switches
 * fix kerneldoc style

Changes since RFC v5
1/4 dt-bindings: net: dsa: add MaxLinear MxL862xx
 * no changes

2/4 net: dsa: add tag format for MxL862xx switches
 * remove unnecessary check for skb != NULL
 * merge consecutively printed warnings into single dev_warn_ratelimited

3/4 net: mdio: add unlocked mdiodev C45 bus accessors
 * no changes

4/4 net: dsa: add basic initial driver for MxL862xx switches
 * include bridge and bridgeport API needed to isolate ports
 * remove warning in .setup as ports are now isolated
 * make ready-after-reset check more robust by adding delay
 * sort structs in order of struct definitions
 * best effort to sort functions without introducing additional prototypes
 * always use enums with kerneldoc comments in mxl862xx-api.h
 * remove bogus .phy_read and .phy_write DSA ops as the driver anyway registers
   a user MDIO bus with Clause-22 and Clause-45 operations
 * various small style fixes

Changes since RFC v4
1/4 dt-bindings: net: dsa: add MaxLinear MxL862xx
 * no changes

2/4 net: dsa: add tag format for MxL862xx switches
 * drop unused precompiler macros

3/4 net: mdio: add unlocked mdiodev C45 bus accessors
 * fix indentation

4/4 net: dsa: add basic initial driver for MxL862xx switches
 * output warning in .setup regarding unknown pre-configuration
 * add comment explaining why CFGGET is used in reset function

Changes since RFC v3
1/4 dt-bindings: net: dsa: add MaxLinear MxL862xx
 * remove labels from example
 * remove 'bindings for' from commit title

2/4 net: dsa: add tag format for MxL862xx switches
 * describe fields and variables with comments
 * sub-interface is only 5 bits
 * harmonize Kconfig symbol name
 * maintain alphabetic order in Kconfig
 * fix typo s/beginnig/beginning/
 * fix typo s/swtiches/switches/
 * arrange local variables in reverse xmas tree order

3/4 net: mdio: add unlocked mdiodev C45 bus accessors
 * unchanged

4/4 net: dsa: add basic initial driver for MxL862xx switches
 * poll switch readiness after reset
 * implement driver shutdown
 * added port_fast_aging API call and driver op
 * unified port setup in new .port_setup op
 * improve comment explaining special handlign for unaligned API read
 * various typos and formatting improvements

Changes since RFC v2
1/4, 2/4, 3/4: unchanged

4/4 net: dsa: add basic initial driver for MxL862xx switches
 * fix return value being uninitialized on error in mxl862xx_api_wrap()
 * add missing description in kerneldoc comment of
   struct mxl862xx_ss_sp_tag

Changes since initial RFC

1/4 dt-bindings: net: dsa: add bindings for MaxLinear MxL862xx
 * better description in dt-bindings doc

2/4 net: dsa: add tag formats for MxL862xx switches
 * make sure all tag fields are initialized

3/4 net: mdio: add unlocked mdiodev C45 bus accessors
 * new patch

4/4 net: dsa: add basic initial driver for MxL862xx switches
 * make use of struct mdio_device
 * add phylink_mac_ops stubs
 * drop leftover nonsense from mxl862xx_phylink_get_caps()
 * fix endian conversions
 * use __le32 instead of enum types in over-the-wire structs
 * use existing MDIO_* macros whenever possible
 * simplify API constants to be more readable
 * use readx_poll_timeout instead of open-coding poll timeout loop
 * add mxl862xx_reg_read() and mxl862xx_reg_write() helpers
 * demystify error codes returned by the firmware
 * add #defines for mxl862xx_ss_sp_tag member values
 * move reset to dedicated function, clarify magic number being the
   reset command ID

Daniel Golle (4):
  dt-bindings: net: dsa: add MaxLinear MxL862xx
  net: dsa: add tag format for MxL862xx switches
  net: mdio: add unlocked mdiodev C45 bus accessors
  net: dsa: add basic initial driver for MxL862xx switches

 .../bindings/net/dsa/maxlinear,mxl862xx.yaml  | 154 ++++
 MAINTAINERS                                   |   8 +
 drivers/net/dsa/Kconfig                       |   2 +
 drivers/net/dsa/Makefile                      |   1 +
 drivers/net/dsa/mxl862xx/Kconfig              |  12 +
 drivers/net/dsa/mxl862xx/Makefile             |   3 +
 drivers/net/dsa/mxl862xx/mxl862xx-api.h       | 675 ++++++++++++++++++
 drivers/net/dsa/mxl862xx/mxl862xx-cmd.h       |  49 ++
 drivers/net/dsa/mxl862xx/mxl862xx-host.c      | 245 +++++++
 drivers/net/dsa/mxl862xx/mxl862xx-host.h      |  12 +
 drivers/net/dsa/mxl862xx/mxl862xx.c           | 475 ++++++++++++
 drivers/net/dsa/mxl862xx/mxl862xx.h           |  19 +
 include/linux/mdio.h                          |  13 +
 include/net/dsa.h                             |   2 +
 net/dsa/Kconfig                               |   7 +
 net/dsa/Makefile                              |   1 +
 net/dsa/tag_mxl862xx.c                        | 112 +++
 17 files changed, 1790 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/dsa/maxlinear,mxl862xx.yaml
 create mode 100644 drivers/net/dsa/mxl862xx/Kconfig
 create mode 100644 drivers/net/dsa/mxl862xx/Makefile
 create mode 100644 drivers/net/dsa/mxl862xx/mxl862xx-api.h
 create mode 100644 drivers/net/dsa/mxl862xx/mxl862xx-cmd.h
 create mode 100644 drivers/net/dsa/mxl862xx/mxl862xx-host.c
 create mode 100644 drivers/net/dsa/mxl862xx/mxl862xx-host.h
 create mode 100644 drivers/net/dsa/mxl862xx/mxl862xx.c
 create mode 100644 drivers/net/dsa/mxl862xx/mxl862xx.h
 create mode 100644 net/dsa/tag_mxl862xx.c

-- 
2.52.0