net: mdio: Introduce a regmap-based mdio driver

There exists several examples today of devices that embed an ethernet
PHY or PCS directly inside an SoC. In this situation, either the device
is contr

net: mdio: Introduce a regmap-based mdio driver

There exists several examples today of devices that embed an ethernet
PHY or PCS directly inside an SoC. In this situation, either the device
is controlled through a vendor-specific register set, or sometimes
exposes the standard 802.3 registers that are typically accessed over
MDIO.

As phylib and phylink are designed to use mdiodevices, this driver
allows creating a virtual MDIO bus, that translates mdiodev register
accesses to regmap accesses.

The reason we use regmap is because there are at least 3 such devices
known today, 2 of them are Altera TSE PCS's, memory-mapped, exposed
with a 4-byte stride in stmmac's dwmac-socfpga variant, and a 2-byte
stride in altera-tse. The other one (nxp,sja1110-base-tx-mdio) is
exposed over SPI.

Signed-off-by: Maxime Chevallier <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

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ipv6: lower "link become ready"'s level message

This following message is printed in the console each time a network
device configured with an IPv6 addresses is ready to be used:

ADDRCONF(NETDEV_

ipv6: lower "link become ready"'s level message

This following message is printed in the console each time a network
device configured with an IPv6 addresses is ready to be used:

ADDRCONF(NETDEV_CHANGE): <iface>: link becomes ready

When netns are being extensively used -- e.g. by re-creating netns' with
veth to discuss with each others for testing purposes like mptcp_join.sh
selftest does -- it generates a lot of messages like that: more than 700
when executing mptcp_join.sh with the latest version.

It looks like this message is not that helpful after all: maybe it can
be used as a sign to know if there is something wrong, e.g. if a device
is being regularly reconfigured by accident? But even then, there are
better ways to monitor and diagnose such issues.

When looking at commit 3c21edbd1137 ("[IPV6]: Defer IPv6 device
initialization until the link becomes ready.") which introduces this new
message, it seems it had been added to verify that the new feature was
working as expected. It could have then used a lower level than "info"
from the beginning but it was fine like that back then: 17 years ago.

It seems then OK today to simply lower its level, similar to commit
7c62b8dd5ca8 ("net/ipv6: lower the level of "link is not ready" messages")
and as suggested by Mat [1], Stephen and David [2].

Link: https://lore.kernel.org/mptcp/[email protected]/T/ [1]
Link: https://lore.kernel.org/netdev/[email protected]/T/ [2]
Suggested-by: Mat Martineau <[email protected]>
Suggested-by: Stephen Hemminger <[email protected]>
Suggested-by: David Ahern <[email protected]>
Signed-off-by: Matthieu Baerts <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

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