Cyclone V SoC Power Optimization

ID 683713
Date 2/09/2015
Public
Document Table of Contents
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1.5.5.2. Using the Driver

  1. Boot the Linux just compiled. From the prompt, add a “new device” to the “sysfs” representation of data from LTC2978A family devices.

    Command format: echo ltc2978 <i2c addr> > /sys/bus/i2c/devices/i2c-<n>/new_device

    Where “i2c addr” is the address of the device on the I2C/PMBus bus and “<n>” is the number of the bus where it resides. Standard I2C utilities can be used to probe the buses.

  2. Add the two LTC2978A devices, using the following commands:
    • HPS Power Monitor: echo ltc2978 0x5c > /sys/bus/i2c/devices/i2c-0/new_device
    • FPGA Power Monitor: echo ltc2978 0x5e > /sys/bus/i2c/devices/i2c-0/new_device
  3. Once the devices are added successfully, files are created in the “sysfs” filesystem for input and output voltages, temperatures and more. Please refer to the LTC2978A datasheet and the kernel documentation mentioned in the "HPS Method: USB Power Management" section for further information on what this driver has provided and how to make use of the data.

Alternately, you can use raw I2C commands to get at the same information, although this driver does some of the number conversions for you.