Kernel driver powr1220
  ==================
  
  Supported chips:
    * Lattice POWR1220AT8
      Prefix: 'powr1220'
      Addresses scanned: none
      Datasheet: Publicly available at the Lattice website
                 http://www.latticesemi.com/
  
  Author: Scott Kanowitz <scott.kanowitz@gmail.com>
  
  Description
  -----------
  
  This driver supports the Lattice POWR1220AT8 chip. The POWR1220
  includes voltage monitoring for 14 inputs as well as trim settings
  for output voltages and GPIOs. This driver implements the voltage
  monitoring portion of the chip.
  
  Voltages are sampled by a 12-bit ADC with a step size of 2 mV.
  An in-line attenuator allows measurements from 0 to 6 V. The
  attenuator is enabled or disabled depending on the setting of the
  input's max value. The driver will enable the attenuator for any
  value over the low measurement range maximum of 2 V.
  
  The input naming convention is as follows:
  
  driver name    pin name
  in0            VMON1
  in1            VMON2
  in2            VMON3
  in2            VMON4
  in4            VMON5
  in5            VMON6
  in6            VMON7
  in7            VMON8
  in8            VMON9
  in9            VMON10
  in10           VMON11
  in11           VMON12
  in12           VCCA
  in13           VCCINP
  
  The ADC readings are updated on request with a minimum period of 1s.