dt-bindings: net: vsc8531: add two additional LED modes for VSC8584

The VSC8584 (and most likely other PHYs in the same generation) has two
additional LED modes that can be picked, so let's add them.

Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Quentin Schulz <quentin.schulz@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: phy: Add LED mode driver for Microsemi PHYs.

LED Mode:
Microsemi PHY support 2 LEDs (LED[0] and LED[1]) to display different
status information that can be selected by setting LED mode.

LED Mode parameter (vsc8531, led-0-mode) and (vsc8531, led-1-mode) get
from Device Tree.

Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@microsemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: phy: Cleanup the Edge-Rate feature in Microsemi PHYs.

Edge-Rate cleanup include the following:
- Updated device tree bindings documentation for edge-rate
- The edge-rate is now specified as a "slowdown", meaning that it is now
being specified as positive values instead of negative (both
documentation and implementation wise).
- Only explicitly documented values for "vsc8531,vddmac" and
"vsc8531,edge-slowdown" are accepted by the device driver.
- Deleted include/dt-bindings/net/mscc-phy-vsc8531.h as it was not needed.
- Read/validate devicetree settings in probe instead of init

Signed-off-by: Allan W. Nielsen <allan.nielsen@microsemi.com>
Signed-off-by: Raju Lakkaraju <raju.lakkaraju@microsemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: phy: Add Edge-rate driver for Microsemi PHYs.

Edge-rate:
As system and networking speeds increase, a signal's output transition,
also know as the edge rate or slew rate (V/ns), takes on greater importance
because high-speed signals come with a price. That price is an assortment of
interference problems like ringing on the line, signal overshoot and
undershoot, extended signal settling times, crosstalk noise, transmission
line reflections, false signal detection by the receiving device and
electromagnetic interference (EMI) -- all of which can negate the potential
gains designers are seeking when they try to increase system speeds through
the use of higher performance logic devices. The fact is, faster signaling
edge rates can cause a higher level of electrical noise or other type of
interference that can actually lead to slower line speeds and lower maximum
system frequencies. This parameter allow the board designers to change the
driving strange, and thereby change the EMI behavioral.

Edge-rate parameters (vddmac, edge-slowdown) get from Device Tree.

Tested on Beaglebone Black with VSC 8531 PHY.

Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@microsemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>