doc/device-tree-bindings/net/fixed-link.txt

Fixed link Device Tree binding
------------------------------

Some Ethernet MACs have a "fixed link", and are not connected to a
normal MDIO-managed PHY device. For those situations, a Device Tree
binding allows to describe a "fixed link".

Such a fixed link situation is described by creating a 'fixed-link'
sub-node of the Ethernet MAC device node, with the following
properties:

* 'speed' (integer, mandatory), to indicate the link speed. Accepted
  values are 10, 100 and 1000
* 'full-duplex' (boolean, optional), to indicate that full duplex is
  used. When absent, half duplex is assumed.
* 'pause' (boolean, optional), to indicate that pause should be
  enabled.
* 'asym-pause' (boolean, optional), to indicate that asym_pause should
  be enabled.

Examples:

ethernet@0 {
	...
	fixed-link {
	      speed = <1000>;
	      full-duplex;
	};
	...
};