Add support for the MDIO multiplexer found in the Amlogic GXL SoC family.
This multiplexer allows to choose between the external (SoC pins) MDIO bus,
or the internal one leading to the integrated 10/100M PHY.

This multiplexer has been handled with the mdio-mux-mmioreg generic driver
so far. When it was added, it was thought the logic was handled by a
single register.

It turns out more than a single register need to be properly set.
As long as the device is using the Amlogic vendor bootloader, or upstream
u-boot with net support, it is working fine since the kernel is inheriting
the bootloader settings. Without net support in the bootloader, this glue
comes unset in the kernel and only the external path may operate properly.

With this driver (and the associated change in
arch/arm64/boot/dts/amlogic/meson-gxl.dtsi), the kernel no longer relies
on the bootloader to set things up, fixing the problem.

Changes since v1:
 * Fix missed checkpatch warnings
 * Change setting function prototype
 * add comment regarding the PHY id

Jerome Brunet (2):
  dt-bindings: net: add amlogic gxl mdio multiplexer
  net: mdio: add amlogic gxl mdio mux support

 .../bindings/net/amlogic,gxl-mdio-mux.yaml    |  64 +++++++
 drivers/net/mdio/Kconfig                      |  11 ++
 drivers/net/mdio/Makefile                     |   1 +
 drivers/net/mdio/mdio-mux-meson-gxl.c         | 164 ++++++++++++++++++
 4 files changed, 240 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/amlogic,gxl-mdio-mux.yaml
 create mode 100644 drivers/net/mdio/mdio-mux-meson-gxl.c

-- 
2.39.0

Hello:

This series was applied to netdev/net-next.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 30 Jan 2023 16:16:14 +0100 you wrote:
> Add support for the MDIO multiplexer found in the Amlogic GXL SoC family.
> This multiplexer allows to choose between the external (SoC pins) MDIO bus,
> or the internal one leading to the integrated 10/100M PHY.
> 
> This multiplexer has been handled with the mdio-mux-mmioreg generic driver
> so far. When it was added, it was thought the logic was handled by a
> single register.
> 
> [...]

Here is the summary with links:
  - [v2,net-next,1/2] dt-bindings: net: add amlogic gxl mdio multiplexer
    https://git.kernel.org/netdev/net-next/c/cc732d235126
  - [v2,net-next,2/2] net: mdio: add amlogic gxl mdio mux support
    https://git.kernel.org/netdev/net-next/c/9a24e1ff4326

You are awesome, thank you!
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