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: 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: stop DMA on halt ...

designware_eqos.c contains an eqos_stop implementation to stop the NIC
when halting the interface. Unfortunately it wasn't used leading to
memory corruption on boot, possibly due to DMA. Fix this.

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

net: eqos: extend Designware Ethernet QoS for Tegra 186 support ...

The U-Boot dwc_eth_qos driver ported in the previous commit had support
for both the Tegra 186/194 and STM32MP variants of the EQOS IP.

The barebox Tegra supported doesn't include the 186, but as the driver
was nevertheless ported along with the rest, lets include it in the
source tree.

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