Merge branch 'NCN26000-PLCA-RS-support'

Piergiorgio Beruto says:

====================
net: add PLCA RS support and onsemi NCN26000

This patchset adds support for getting/setting the Physical Layer
Collision Avoidace (PLCA) Reconciliation Sublayer (RS) configuration and
status on Ethernet PHYs that supports it.

PLCA is a feature that provides improved media-access performance in terms
of throughput, latency and fairness for multi-drop (P2MP) half-duplex PHYs.
PLCA is defined in Clause 148 of the IEEE802.3 specifications as amended
by 802.3cg-2019. Currently, PLCA is supported by the 10BASE-T1S single-pair
Ethernet PHY defined in the same standard and related amendments. The OPEN
Alliance SIG TC14 defines additional specifications for the 10BASE-T1S PHY,
including a standard register map for PHYs that embeds the PLCA RS (see
PLCA management registers at https://www.opensig.org/about/specifications/).

The changes proposed herein add the appropriate ethtool netlink interface
for configuring the PLCA RS on PHYs that supports it. A separate patchset
further modifies the ethtool userspace program to show and modify the
configuration/status of the PLCA RS.

Additionally, this patchset adds support for the onsemi NCN26000
Industrial Ethernet 10BASE-T1S PHY that uses the newly added PLCA
infrastructure.
====================

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