Ralink MIPS SoC device tree bindings

1. SoCs

Each device tree must specify a compatible value for the Ralink SoC
it uses in the compatible property of the root node. The compatible
value must be one of the following values:

  ralink,rt2880-soc
  ralink,rt3050-soc
  ralink,rt3052-soc
  ralink,rt3350-soc
  ralink,rt3352-soc
  ralink,rt3883-soc
  ralink,rt5350-soc
  ralink,mt7620a-soc
  ralink,mt7620n-soc
  ralink,mt7628a-soc
