[RFC PATCH net-next v2 00/10] Introduce PHY listing and link_topology tracking

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

Hello everyone,

As part of the ongoing effort to better describe the ethernet link
topology, this series introduces the first step by allowing to maintain
a list of all the ethernet PHYs that are connected to a given netdevice.

For now, this can happen when using a PHY as a media converter :

   MAC - PHYa - SFP - PHYb (in SFP module)

The issue with the above is that from userspace, we can only interact
with PHYa, as it's referenced by netdev->phydev, used in PHY-specific
netlink commands. This series therefore proposes to keep track of all
PHYs, through the struct link_topology, owned by struct
net_device. Phylib is therefore registering all PHYs and information on
their parent device, through direct attachment to a MAC or as part of an
SFP bus. This is done by patches 1 to 3.

Patches 4 to 6 introduce a new netlink command to get/dump the PHYs on a
given interface, with enough information to reconstruct the whole
topology, especially if we have chained PHYs.

Patches 7 to 10 are a proposition to extend the PLCA, PSE-PD, Cabletest
and stats reporting commands to take the PHY index into account, however
I only did minimal testing on these, and I'd like feedback on the idea.

Although more complete, this is still RFC, but I have some followup
series for a better port representation that depends on it, which I can
include for next revisions, but I don't want to make the series too big.

The first RFC was much less compete, but can be found here [1].

The overall topic was presented at Netdev 0x17 [2]

Best regards,

Maxime

[1] : https://lore.kernel.org/netdev/20230907092407.647139-1-maxime.chevallier@bootlin.com/
[2] : https://bootlin.com/pub/conferences/2023/netdev/multi-port-multi-phy-interfaces.pdf

Maxime Chevallier (10):
  net: phy: Introduce ethernet link topology representation
  net: sfp: pass the phy_device when disconnecting an sfp module's PHY
  net: phy: add helpers to handle sfp phy connect/disconnect
  net: sfp: Add helper to return the SFP bus name
  net: ethtool: Allow passing a phy index for some commands
  net: ethtool: Introduce a command to list PHYs on an interface
  net: ethtool: plca: Target the command to the requested PHY
  net: ethtool: pse-pd: Target the command to the requested PHY
  net: ethtool: cable-test: Target the command to the requested PHY
  net: ethtool: strset: Allow querying phy stats by index

 Documentation/netlink/specs/ethtool.yaml     |  69 ++++-
 Documentation/networking/ethtool-netlink.rst |  51 ++++
 MAINTAINERS                                  |   1 +
 drivers/net/phy/Makefile                     |   2 +-
 drivers/net/phy/at803x.c                     |   2 +
 drivers/net/phy/link_topology.c              |  78 ++++++
 drivers/net/phy/marvell-88x2222.c            |   2 +
 drivers/net/phy/marvell.c                    |   2 +
 drivers/net/phy/marvell10g.c                 |   2 +
 drivers/net/phy/phy_device.c                 |  54 ++++
 drivers/net/phy/phylink.c                    |   3 +-
 drivers/net/phy/sfp-bus.c                    |  13 +-
 include/linux/ethtool_netlink.h              |   5 +
 include/linux/link_topology.h                |  59 ++++
 include/linux/link_topology_core.h           |  17 ++
 include/linux/netdevice.h                    |   3 +-
 include/linux/phy.h                          |   5 +
 include/linux/sfp.h                          |   8 +-
 include/uapi/linux/ethtool.h                 |   7 +
 include/uapi/linux/ethtool_netlink.h         |  30 ++
 net/core/dev.c                               |   4 +
 net/ethtool/Makefile                         |   2 +-
 net/ethtool/cabletest.c                      |  12 +-
 net/ethtool/netlink.c                        |  30 ++
 net/ethtool/netlink.h                        |  11 +-
 net/ethtool/phy.c                            | 279 +++++++++++++++++++
 net/ethtool/plca.c                           |  13 +-
 net/ethtool/pse-pd.c                         |  14 +-
 net/ethtool/strset.c                         |  15 +-
 29 files changed, 752 insertions(+), 41 deletions(-)
 create mode 100644 drivers/net/phy/link_topology.c
 create mode 100644 include/linux/link_topology.h
 create mode 100644 include/linux/link_topology_core.h
 create mode 100644 net/ethtool/phy.c

-- 
2.41.0