mdio is a low-level Linux debug tool for communicating with devices attached an MDIO bus. It improves on existing tools in this space in a few important ways:

MDIO buses are directly addressable. Previous solutions relied on at least one Ethernet PHY on the bus being attached to a net device, which is typically not the case when the device is an Ethernet switch for example.
Complex operations can be performed atomically. The old API only supported a single read or write of a single register. mdio sends byte code to the mdio-netlink kernel module that can perform multiple operations, store intermediate values, loop etc. As a result, things like read/mask/write operations and accesses to paged PHYs can be performed safely.

Signed-off-by: Damien Mascord <tusker@tusker.org>