Merge branch 'net-phy-add-Lynx-PCS-MDIO-module'

Merge branch 'net-phy-add-Lynx-PCS-MDIO-module'

Ioana Ciornei says:

====================
net: phy: add Lynx PCS MDIO module

Add support for the Lynx PCS as a separate module in drivers/net/phy/.
The advantage of this structure is that multiple ethernet or switch
drivers used on NXP hardware (ENETC, Seville, Felix DSA switch etc) can
share the same implementation of PCS configuration and runtime
management.

The module implements phylink_pcs_ops and exports a phylink_pcs
(incorporated into a lynx_pcs) which can be directly passed to phylink
through phylink_pcs_set.

The first 3 patches add some missing pieces in phylink and the locked
mdiobus write accessor. Next, the Lynx PCS MDIO module is added as a
standalone module. The majority of the code is extracted from the Felix
DSA driver. The last patch makes the necessary changes in the Felix and
Seville drivers in order to use the new common PCS implementation.

At the moment, USXGMII (only with in-band AN), SGMII, QSGMII (with and
without in-band AN) and 2500Base-X (only w/o in-band AN) are supported
by the Lynx PCS MDIO module since these were also supported by Felix and
no functional change is intended at this time.

Changes in v2:
 * got rid of the mdio_lynx_pcs structure and directly exported the
 functions without the need of an indirection
 * made the necessary adjustments for this in the Felix DSA driver
 * solved the broken allmodconfig build test by making the module
 tristate instead of bool
 * fixed a memory leakage in the Felix driver (the pcs structure was
 allocated twice)

Changes in v3:
 * added support for PHYLINK PCS ops in DSA (patch 5/9)
 * cleanup in Felix PHYLINK operations and migrate to
 phylink_mac_link_up() being the callback of choice for applying MAC
 configuration (patches 6-8)

Changes in v4:
 * use the newly introduced phylink PCS mechanism
 * install the phylink_pcs in the phylink_mac_config DSA ops
 * remove the direct implementations of the PCS ops
 * do no use the SGMII_ prefix when referring to the IF_MORE register
 * add a phylink helper to decode the USXGMII code word
 * remove cleanup patches for Felix (these have been already accepted)
 * Seville (recently introduced) now has PCS support through the same
 Lynx PCS module

Changes in v5:
 - move the pcs-lynx driver to drivers/net/pcs
 - reword the commit message a bit in 4/5
 - add error checking and error propagation in 4/5
 - s/IF_MODE_DUPLEX/IF_MODE_HALF_DUPLEX in 4/5
====================

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