Merge branch 'mscc-ocelot-add-support-for-SerDes-muxing-configuration'

Quentin Schulz says:

====================
mscc: ocelot: add support for SerDes muxing configuration

The Ocelot switch has currently an hardcoded SerDes muxing that suits only
a particular use case. Any other board setup will fail to work.

To prepare for upcoming boards' support that do not have the same muxing,
create a PHY driver that will handle all possible cases.

A SerDes can work in SGMII, QSGMII or PCIe and is also muxed to use a
given port depending on the selected mode or board design.

The SerDes configuration is in the middle of an address space (HSIO) that
is used to configure some parts in the MAC controller driver, that is why
we need to use a syscon so that we can write to the same address space from
different drivers safely using regmap.

This breaks backward compatibility but it's fine because there's only one
board at the moment that is using what's modified in this patch series.
This will break git bisect.

Even though this patch series is about SerDes __muxing__ configuration, the
DT node is named serdes for the simple reason that I couldn't find any
mention to SerDes anywhere else from the address space handled by this
driver.

v4:
  - add reviewed-by,
  - format the patch series with -M for identifying renamed files,
  - add parent info in DT binding of the SerDes IP,
  - move to macros SERDES[16]G(X) instead of multiple SERDES[16]G_[012345]
  constants,
  - move to SERDES[16]G_MAX being the last VALID macro of a type, so
  migrate to <= conditions instead of < when iterating,
  - create a SERDES_MUX_SGMII and SERDES_MUX_QSGMII macro so the muxing
  configurations are a tad more readable,
  - use a bunch of unsigned int instead of int,
  - return -EOPNOTSUPP for SERDES6G/PCIe until it's supported,
  - simplify condition when there is an error code returned by
  devm_of_phy_get,

v3:
  - add Paul Burton's Acked-By on MIPS patches so that the patch series can
  be merged in the net tree in its entirety,

v2:
  - use a switch case for setting the phy_mode in the SerDes driver as
  suggested by Andrew,
  - stop replacing the value of the error pointer in the SerDes driver,
  - use a dev_dbg for the deferring of the probe in the SerDes driver,
  - use constants in the Device Tree to select the SerDes macro in use with
  a port,
  - adapt the SerDes driver to use those constants,
  - add a header file in include/dt-bindings for the constants,
  - fix space/tab issue,
====================

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