net: phy: fixed: Be compatible with live OF tree

net: phy: fixed: Be compatible with live OF tree

On systems that use CONFIG_OF_LIVE, the "ofnode" type is defined
as const struct device_node *np, while on the flat DT systems it
is defined as a long of_offset into gd->fdt_blob.

It is desirable that the fixed PHY driver uses the higher-level
ofnode abstraction instead of parsing gd->fdt_blob directly,
because that enables it to work on live OF systems.

The fixed PHY driver has used a nasty hack since its introduction in
commit db40c1aa1c10 ("drivers/net/phy: add fixed-phy /
fixed-link support"),
which is to pass the long gd->fdt_blob offset inside int phydev->addr
(a value that normally holds the MDIO bus address at which the PHY
responds). Even ignoring the fact that the types were already
mismatched leading to a potential truncation (flat OF offset was
supposed to be a long and not an int), we really cannot extend this
hack any longer, because there's no way an int will hold the other
representation of ofnode, the struct device_node *np.

So we unfortunately need to do the right thing, which is to use the
framework introduced by Grygorii Strashko in
commit eef0b8a930d1 ("net: phy: add ofnode node to struct phy_device").
This will populate phydev->node for the fixed PHY.

Note that phydev->node will not be valid in the probe function, since
that is called synchronously from phy_device_create and we really have
no way of passing the ofnode directly through the phy_device_create API.
So we do what other drivers do too: we move the OF parsing logic from
the .probe to the .config method of the PHY driver. The new function
will be called at phy_config() time.

I do believe I've converted all the possible call paths for creating
a PHY with PHY_FIXED_ID, so there is really no reason to maintain
compatibility with the old logic of retrieving a flat OF tree offset
from phydev->addr. We just pass 0 to phydev->addr now.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Message-Id: <20210216224804.3355044-2-olteanv@gmail.com>
[bmeng: keep fixedphy_probe(); update mdio-uclass.c to handle fixed phy]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>