Switch configuration
--------------------
-- priv_size: additional size needed by the switch driver for its private context
-
- tag_protocol: this is to indicate what kind of tagging protocol is supported,
should be a valid value from the dsa_tag_protocol enum
to the switch port MDIO registers. If unavailable return a negative error
code.
-- poll_link: Function invoked by DSA to query the link state of the switch
- builtin Ethernet PHYs, per port. This function is responsible for calling
- netif_carrier_{on,off} when appropriate, and can be used to poll all ports in a
- single call. Executes from workqueue context.
-
- adjust_link: Function invoked by the PHY library when a slave network device
is attached to a PHY device. This function is responsible for appropriately
configuring the switch port link parameters: speed, duplex, pause based on
Bridge VLAN filtering
---------------------
+- port_vlan_filtering: bridge layer function invoked when the bridge gets
+ configured for turning on or off VLAN filtering. If nothing specific needs to
+ be done at the hardware level, this callback does not need to be implemented.
+ When VLAN filtering is turned on, the hardware must be programmed with
+ rejecting 802.1Q frames which have VLAN IDs outside of the programmed allowed
+ VLAN ID map/rules. If there is no PVID programmed into the switch port,
+ untagged frames must be rejected as well. When turned off the switch must
+ accept any 802.1Q frames irrespective of their VLAN ID, and untagged frames are
+ allowed.
+
- port_vlan_prepare: bridge layer function invoked when the bridge prepares the
configuration of a VLAN on the given port. If the operation is not supported
by the hardware, this function should return -EOPNOTSUPP to inform the bridge