net: designware: eqos: mimic Linux gmac4 mdio_{read, write} ...

The code was ported over from U-Boot and has some things different than
the Kernel driver:

- It reads ->mdio_address, but the kernel driver doesn't
- It doesn't write ->mdio_data in a read, but the kernel driver does
- It has delays in addition to spinning on MII_BUSY, but the kernel driver
  doesn't

Adopt the same flow as used by the kernel.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

net: designware: eqos: remove left-over PHY quirk work around ...

The dummy read was a left over from an abandoned merge with the existing
support for the SoCFPGA variant of the Designware MAC. It doesn't exist
in either the U-Boot or kernel drivers for the EQOS, thus drop it.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

net: designware: eqos: don't funnel all MDIO writes to register 0 ...

eqos_mdio_write ended up using the addr parameter instead of the
computed miiaddr variable, which would've factored in the reg parameter.

This had the effect that all writes went to PHY register 0, which was
fine as long as there were only register 0 writes. As soon there are more
writes, e.g. because a PHY driver was enabled, register 0 became
clobbered and erratic behavior ensued.
Fix the typo and while at it rename the val parameter to a more
descriptive name.

Fixes: a4f709bbb ("net: add Designware Ethernet QoS for STM32MP")
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

net: designware: eqos: fix NULL pointer use in dev_printf ...

Inside mdio_register, a read of the PHY's id register is attempted.
If it fails, we print an error message with eqos_err, which uses the
ethernet device's unique name, but at this time there has been none set,
because eth_register was not yet called. Fix this by using the MDIO bus
device instead.

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

net: designware: eqos: enable clocks before mdio_register ...

We can't be using the MAC including the MDIO controller while the clocks
are off, but this is exactly the case when mdio_register is called and
the interface is not yet up. To allow reading the PHY id to succeed
before the interface is up, turn on the clocks as part of the
initialization in the probe.

This fixes following error at probe time:

    ERROR: <NULL>: MDIO not idle at entry

The NULL is fixed in a follow-up commit.

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

net: designware: eqos: properly stop DMA on halt ...

Specifying ->halt only means that it's called along with eth_unregister.
If we want to halt the DMA, we will have to call it ourselves in the
remove callback. Do this.

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

net: add Designware Ethernet QoS for STM32MP ...

We already have Designware NIC support in barebox, but for the DWMAC1000,
the DWMAC4 (also called GMAC4), no support was mainline so far.

The DWMAC4 is different enough that sharing code with the DWMAC1000 is
not really that helpful, because even basics like MDIO registers have
different layout. Instead of coding bit masks and shifts into the driver
data, like Linux does, we'll keep both driver kinds separate.

Nevertheless, we collect functions that are not SoC-specific into a
separate 'library' file.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>