This commit introduces support for etherswitch devices that utilize SMI as
a way of accessing its registers. SMI register is located in address space
of mge -- access to it was exported through MDIO interface.
Attachment functions were enhanced so as to ensure proper initialisation
in both cases: 1) PHYs attached directly to mge, 2) PHYs attached to
switch device and switch attached to mge. Attachment of etherswitch device
depends on dts entry with compatible="mrvl,sw" property. If none is found,
typical PHY attachment procedure follows.
In case of switch attached, PHYs' status and configuration is accessible
via etherswitchcfg, and ifconfig shows always-up, non-configurable mge
interfaces.
Due to the fact that there may be simultaneous accessess to SMI
registers (e.g. from PHY attached to one of mge instances and switch
to the other), SMI access interlock was added. It is SX lock,
because sleep ability is necessary -- busy-waiting would result
in poor performance due to long delays required by hardware.
Underlying switch driver is obliged to use sleepable locks as well.
Reviewed by: adrian
Obtained from: Semihalf
Submitted by: Bartosz Szczepanek <bsz@semihalf.com>
Differential revision: https://reviews.freebsd.org/D3900
4a3e4c4e49