dt-bindings: net: Add a YAML schemas for the generic MDIO options

The MDIO buses have a number of available device tree properties that can
be used in their device tree node. Add a YAML schemas for those.

Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>

dt-bindings: Remove leading 0x from bindings notation

Improve the binding example by removing all the leading 0x to fix the
following dtc warnings:

Warning (unit_address_format): Node /XXX unit name should not have leading "0x"

Converted using the following command:

find Documentation/devicetree/bindings -name "*.txt" -exec sed -i -e 's/([^ ])\@0x([0-9a-f])/$1\@$2/g' {} +

This is a follow up to commit 48c926cd3414

Signed-off-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Rob Herring <robh@kernel.org>

dt-bindings: mdio: Clarify binding document

The described GPIO reset property is applicable to *all* child PHYs. If
we have one reset line per PHY present on the MDIO bus, these
automatically become properties of the child PHY nodes.

Finally, indicate how the RESET pulse width must be defined, which is
the maximum value of all individual PHYs RESET pulse widths determined
by reading their datasheets.

Fixes: 69226896ad63 ("mdio_bus: Issue GPIO RESET to PHYs.")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mdio_bus: Issue GPIO RESET to PHYs.

Some boards [1] leave the PHYs at an invalid state
during system power-up or reset thus causing unreliability
issues with the PHY which manifests as PHY not being detected
or link not functional. To fix this, these PHYs need to be RESET
via a GPIO connected to the PHY's RESET pin.

Some boards have a single GPIO controlling the PHY RESET pin of all
PHYs on the bus whereas some others have separate GPIOs controlling
individual PHY RESETs.

In both cases, the RESET de-assertion cannot be done in the PHY driver
as the PHY will not probe till its reset is de-asserted.
So do the RESET de-assertion in the MDIO bus driver.

[1] - am572x-idk, am571x-idk, a437x-idk

Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>