Merge branch 'net-pcs-rzn1-miic-support-configurable-phy_link-polarity'

Merge branch 'net-pcs-rzn1-miic-support-configurable-phy_link-polarity'

Lad Prabhakar says:

====================
net: pcs: rzn1-miic: Support configurable PHY_LINK polarity

This series adds support for configuring the active level of MIIC
PHY_LINK status signals on Renesas RZ/N1 and RZ/T2H/N2H platforms.

The MIIC block provides dedicated hardware PHY_LINK signals that indicate
EtherPHY link-up and link-down status independently of whether the MAC
(GMAC) or Ethernet switch (ETHSW) is used. While GMAC-based systems
typically obtain link state via MDIO and handle it in software, the
ETHSW relies on these PHY_LINK pins for both CPU-assisted operation and
switch-only forwarding paths that do not involve the host processor.

These hardware PHY_LINK signals are particularly important for use cases
requiring fast reaction to link-down events, such as redundancy protocols
including Device Level Ring (DLR). In such scenarios, relying solely on
software-based link detection introduces latency that can negatively
impact recovery time. The ETHSW therefore exposes PHY_LINK signals to
enable immediate hardware-level detection of cable or port failures.

Some systems require the PHY_LINK signal polarity to be configured as
active low rather than the default active high. This series introduces a
new DT property to describe the required polarity and adds corresponding
driver support to program the MIIC PHY_LINK register accordingly. The
configuration is accumulated during DT parsing and applied once hardware
initialization is complete, taking into account SoC-specific differences
between RZ/N1 and RZ/T2H/N2H.
====================

Link: https://patch.msgid.link/20260112173555.1166714-1-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>