This small series add the initial support for the Airoha AN8855 Switch.

It's a 5 port Gigabit Switch with SGMII/HSGMII upstream port.

This is starting to get in the wild and there are already some router
having this switch chip.

It's conceptually similar to mediatek switch but register and bits
are different. And there is that massive Hell that is the PCS
configuration.
Saddly for that part we have absolutely NO documentation currently.

There is this special thing where PHY needs to be calibrated with values
from the switch efuse. (the thing have a whole cpu timer and MCU)

Some cleanup API are used and one extra patch for mdio_mutex_nested is
introduced. As suggested some time ago, the use of such API is limited
to scoped variants and not the guard ones.

Posting as RFC as I expect in later version to add additional feature
but this is already working and upstream-ready. So this is really to
have a review of the very basic features and if I missed anything in
recent implementation of DSA.

Changes v3:
- Out of RFC
- Switch PHY code to select_page API
- Better describe masks and bits in PHY driver for ADC register
- Drop raw values and use define for mii read/write
- Switch to absolute PHY address
- Replace raw values with mask and bits for pcs_config
- Fix typo for ext-surge property name
- Drop support for relocating Switch base PHY address on the bus
Changes v2:
- Drop mutex guard patch
- Drop guard usage in DSA driver
- Use __mdiobus_write/read
- Check return condition and return errors for mii read/write
- Fix wrong logic for EEE
- Fix link_down (don't force link down with autoneg)
- Fix forcing speed on sgmii autoneg
- Better document link speed for sgmii reg
- Use standard define for sgmii reg
- Imlement nvmem support to expose switch EFUSE
- Rework PHY calibration with the use of NVMEM producer/consumer
- Update DT with new NVMEM property
- Move aneg validation for 2500-basex in pcs_config
- Move r50Ohm table and function to PHY driver

Christian Marangi (3):
  dt-bindings: net: dsa: Add Airoha AN8855 Gigabit Switch documentation
  net: dsa: Add Airoha AN8855 5-Port Gigabit DSA Switch driver
  net: phy: Add Airoha AN8855 Internal Switch Gigabit PHY

 .../bindings/net/dsa/airoha,an8855.yaml       |  242 ++
 MAINTAINERS                                   |   11 +
 drivers/net/dsa/Kconfig                       |    9 +
 drivers/net/dsa/Makefile                      |    1 +
 drivers/net/dsa/an8855.c                      | 2054 +++++++++++++++++
 drivers/net/dsa/an8855.h                      |  628 +++++
 drivers/net/phy/Kconfig                       |    5 +
 drivers/net/phy/Makefile                      |    1 +
 drivers/net/phy/air_an8855.c                  |  278 +++
 9 files changed, 3229 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/dsa/airoha,an8855.yaml
 create mode 100644 drivers/net/dsa/an8855.c
 create mode 100644 drivers/net/dsa/an8855.h
 create mode 100644 drivers/net/phy/air_an8855.c

-- 
2.45.2