Merge branch 'phy-listing-link_topology-tracking'

Maxime Chevallier says:

====================
Introduce PHY listing and link_topology tracking

Here's a V5 of the multi-PHY support series.

At a glance, besides some minor fixes and R'd-by from Andrew, one of the
thing this series does is remove the ASSERT_RTNL() from the
topo_add_phy/del_phy operations.

These operations will take a PHY device and put it into the list of
devices associated to a netdevice. The main thing to protect here is the
list itself, but since we use xarrays, my naive understanding of it is
that it contains its own protection scheme. There shouldn't be a need
for more locking, as the insertion/deletion paths are already hooked
into the PHY connection to a netdev, or disconnection from it.

Now for the rest of the cover :

As a remainder, this ongoing work aims ultimately at supporting complex
link topologies that involve multiplexing multiple PHYs/SFPs on a single
netdevice. As a first step, it's required that we are able to enumerate the
PHYs on a given ethernet interface.

By just doing so, we also improve already-existing use-cases, namely the
copper SFP modules support when a media-converter is used (as we have 2
PHYs on the link, but only one is referenced by net_device.phydev, which
is used on a variety of netlink commands).

The series is architectured as follows :

- The first patch adds the notion of phy_link_topology, which tracks
all PHYs attached to a netdevice.

- Patches 2, 3 and 4 adds some plumbing into SFP and phylib to be able
  to connect the dots when building the topology tree, to know which PHY
  is connected to which SFP bus, trying not to be too invasive on phylib.

- Patch 5 allows passing a PHY_INDEX to ethnl commands. I'm uncertain about
  this, as there are at least 4 netlink commands ( 5 with the one introduced
  in patch 7 ) that targets PHYs directly or indirectly, which to me makes
  it worth-it to have a generic way to pass a PHY index to commands, however
  the approach taken may be too generic.

- Patch 6 is the netlink spec update + ethtool-user.c|h autogenerated code
update (the autogenerated code triggers checkpatch warning though)

- Patch 7 introduces a new netlink command set to list PHYs on a netdevice.
It implements a custom DUMP and GET operation to allow filtered dumps,
that lists all PHYs on a given netdevice. I couldn't use most of ethnl's
plumbing though.

- Patch 8 is the netlink spec update + ethtool-user.c|h update for that
new command

- Patch 8,9,10 and 11 updates the PLCA, strset, cable-test and pse netlink
commands to use the user-provided PHY instead of net_device.phydev.

- Finally patch 12 adds some documentation for this whole work.

Examples
========

Here's a short overview of the kind of operations you can have regarding
the PHY topology. These tests were performed on a MacchiatoBin, which
has 3 interfaces :

eth0 and eth1 have the following layout:

MAC - PHY - SFP

eth2 has this more classic topology :

MAC - PHY - RJ45

finally eth3 has the following topology :

MAC - SFP

When performing a dump with all interfaces down, we don't get any
result, as no PHY has been attached to their respective net_device :

None

The following output is with eth0, eth2 and eth3 up, but no SFP module
inserted in none of the interfaces :

[{'downstream-sfp-name': 'sfp-eth0',
  'drvname': 'mv88x3310',
  'header': {'dev-index': 2, 'dev-name': 'eth0'},
  'id': 0,
  'index': 1,
  'name': 'f212a600.mdio-mii:00',
  'upstream-type': 'mac'},
 {'drvname': 'Marvell 88E1510',
  'header': {'dev-index': 4, 'dev-name': 'eth2'},
  'id': 21040593,
  'index': 1,
  'name': 'f212a200.mdio-mii:00',
  'upstream-type': 'mac'}]

And now is a dump operation with a copper SFP in the eth0 port :

[{'downstream-sfp-name': 'sfp-eth0',
  'drvname': 'mv88x3310',
  'header': {'dev-index': 2, 'dev-name': 'eth0'},
  'id': 0,
  'index': 1,
  'name': 'f212a600.mdio-mii:00',
  'upstream-type': 'mac'},
 {'drvname': 'Marvell 88E1111',
  'header': {'dev-index': 2, 'dev-name': 'eth0'},
  'id': 21040322,
  'index': 2,
  'name': 'i2c:sfp-eth0:16',
  'upstream': {'index': 1, 'sfp-name': 'sfp-eth0'},
  'upstream-type': 'phy'},
 {'drvname': 'Marvell 88E1510',
  'header': {'dev-index': 4, 'dev-name': 'eth2'},
  'id': 21040593,
  'index': 1,
  'name': 'f212a200.mdio-mii:00',
  'upstream-type': 'mac'}]

 -- Note that this shouldn't actually work as the 88x3310 PHY doesn't allow
a 1G SFP to be connected to its SFP interface, and I don't have a 10G copper SFP,
so for the sake of the demo I applied the following modification, which
of courses gives a non-functionnal link, but the PHY attach still works,
which is what I want to demonstrate :

@@ -488,7 +488,7 @@ static int mv3310_sfp_insert(void *upstream, const struct sfp_eeprom_id *id)

        if (iface != PHY_INTERFACE_MODE_10GBASER) {
                dev_err(&phydev->mdio.dev, "incompatible SFP module inserted\n");
-               return -EINVAL;
+               //return -EINVAL;
        }
        return 0;
 }

Finally an example of the filtered DUMP operation that Jakub suggested
in V1 :

[{'downstream-sfp-name': 'sfp-eth0',
  'drvname': 'mv88x3310',
  'header': {'dev-index': 2, 'dev-name': 'eth0'},
  'id': 0,
  'index': 1,
  'name': 'f212a600.mdio-mii:00',
  'upstream-type': 'mac'},
 {'drvname': 'Marvell 88E1111',
  'header': {'dev-index': 2, 'dev-name': 'eth0'},
  'id': 21040322,
  'index': 2,
  'name': 'i2c:sfp-eth0:16',
  'upstream': {'index': 1, 'sfp-name': 'sfp-eth0'},
  'upstream-type': 'phy'}]

And a classic GET operation allows querying a single PHY's info :

{'drvname': 'Marvell 88E1111',
 'header': {'dev-index': 2, 'dev-name': 'eth0'},
 'id': 21040322,
 'index': 2,
 'name': 'i2c:sfp-eth0:16',
 'upstream': {'index': 1, 'sfp-name': 'sfp-eth0'},
 'upstream-type': 'phy'}

Changed in V5:
- Removed the RTNL assertion in the topology ops
- Made the phy_topo_get_phy inline
- Fixed the PSE-PD multi-PHY support by re-adding a wrongly dropped
  check
- Fixed some typos in the documentation
- Fixed reverse xmas trees

Changes in V4:
- Dropped the RFC flag
- Made the net_device integration independent to having phylib enabled
- Removed the autogenerated ethtool-user code for the YNL specs

Changes in V3:
- Added RTNL assertions where needed
- Fixed issues in the DUMP code for PHY_GET, which crashed when running it
  twice in a row
- Added the documentation, and moved in-source docs around
- renamed link_topology to phy_link_topology

Changes in V2:
- Added the DUMP operation
- Added much more information in the reported data, to be able to reconstruct
  precisely the topology tree
- renamed phy_list to link_topology
====================

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

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