Merge branch 'phy-motorcomm-driver-strength'

Merge branch 'phy-motorcomm-driver-strength'

Samin Guo says:

====================
Add motorcomm phy pad-driver-strength-cfg support

The motorcomm phy (YT8531) supports the ability to adjust the drive
strength of the rx_clk/rx_data, and the default strength may not be
suitable for all boards. So add configurable options to better match
the boards.(e.g. StarFive VisionFive 2)

The first patch adds a description of dt-bingding, and the second patch adds
YT8531's parsing and settings for pad-driver-strength-cfg.

Changes since v4:
Patch 1:
- Removed register-related DS(3b) values and added vol descriptions (by Andrew Lunn)
- Dropped the type and added '-microamp' suffix. (by Rob Herring)
Patch 2:
- Return -EINVAL if the value in DT but it is invalid (by Andrew Lunn)

Changes since v3:
Patch 1:
- Used current values instead of register values
- Added units and numerical descriptions of driver-strength
Patch 2:
- Added a lookup table to listing the valid values in the schema (by Andrew Lunn)

Changes since v2:
Patch 2:
- Readjusted the order of YT8531_RGMII_xxx to below YTPHY_PAD_DRIVE_STRENGTH_REG (by Frank Sae)
- Reversed Christmas tree, sort these longest first, shortest last (by Andrew Lunn)
- Rebased on tag v6.4

Changes since v1:
Patch 1:
- Renamed "rx-xxx-driver-strength" to "motorcomm,rx-xxx-driver-strength" (by Frank Sae)
Patch 2:
- Added default values for rxc/rxd driver strength (by Frank Sea/Andrew Lunn)
- Added range checking when val is in DT (by Frank Sea/Andrew Lunn)

Previous versions:
v1 - https://patchwork.kernel.org/project/netdevbpf/cover/20230426063541.15378-1-samin.guo@starfivetech.com
v2 - https://patchwork.kernel.org/project/netdevbpf/cover/20230505090558.2355-1-samin.guo@starfivetech.com
v3 - https://patchwork.kernel.org/project/netdevbpf/cover/20230526090502.29835-1-samin.guo@starfivetech.com
v4 - https://patchwork.kernel.org/project/netdevbpf/cover/20230714101406.17686-1-samin.guo@starfivetech.com
====================

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