[PATCH v2 0/3] phy: Realtek Otto SerDes: add new driver

[Markus Stockhausen]

This patch series adds support for the SerDes in the Realtek Otto platform.
These are 8-52 port switch SoCs of the RTL83xx and RTL93xx series with MIPS
cores. The ports are based on 1-8 port PHYs (e.g. RTL8218D) that are connected
via multiple SerDes.

The driver is based on the GPL source drops from the different switch vendors.
It supports all 4 SoC series and was developed and tested on the following
devices:

RTL838x - codename maple - Linksys LGS310C
RTL839x - codename cypress - Zyxel GS1920-24
RTL930x - codename langon - Zyxel XGS1210-10
RTL931x - codename mango - Linksys LGS352C

Due to very little information and fundamentally different I/O handling and
port ranges of the devices the driver assumes and translates some handling
to provide a common consistent interface.

Currently only provide the most basic operations for mode set and device
reset as well as some debugging information if enabled. The strength lies in
the fact that the driver can run patch sequences for the SerDes registers at
certain events, e.g. during setup. This allows to run configuration
operations to get the SerDes up and running. For now provide setup sequences
for RTL838x and RTL839x devices.

For more information see:

https://svanheule.net/switches/gpl_source_drops
https://svanheule.net/realtek/