eeprom.ex

defmodule NervesBBBEEPROM do
  @moduledoc """
  Documentation for NervesBbbEeprom.
  """

  @doc """
  Hello world.

  ## Examples

      iex> NervesBbbEeprom.hello
      :world

  """

  # @eeprom_device "/sys/bus/i2c/devices/0-0050/eeprom"
  # @ti_nvs_file "/lib/firmware/ti-connectivity/wl127x-nvs.bin"
  @eeprom_device "../eeprom.bin"
  @ti_nvs_file "../wl127x-nvs.bin"

  defstruct header: nil, id: nil, version: nil, serial: nil, mac_hex: "000000000000", mac_bytes: <<0, 0, 0, 0, 0, 0>>

  @spec read_and_parse_eeprom :: {:ok, %NervesBBBEEPROM{}} | {:error, :atom}
  def read_and_parse_eeprom do
    case File.open(@eeprom_device) do
      {:ok, file} ->
        eeprom = IO.binread(file, 28)
        :file.position(file, 0x3c)
        mac_hex = IO.binread(file, 12)
        File.close(file)

        <<header::binary-size(4),
          id::binary-size(8),
          version::binary-size(4),
          serial::binary-size(12),
        >> = eeprom

        case Base.decode16(mac_hex) do
          {:ok, mac_bytes} ->
            %NervesBBBEEPROM{
              header: header,
              id: id,
              version: version,
              serial: serial,
              mac_hex: mac_hex,
              mac_bytes: mac_bytes
            }
          err -> err
        end
      err -> err
    end
  end

  @spec write_mac_to_nvs_file(<<_::6>>) :: :ok | {:error, :atom}
  def write_mac_to_nvs_file(<<0xff, 0xff, 0xff, 0xff, 0xff, 0xff>>), do: write_mac_to_nvs_file(<<0, 0, 0, 0, 0, 0>>)
  def write_mac_to_nvs_file(<<b1, b2, b3, b4, b5, b6>>) do
    case File.exists?(@ti_nvs_file) do
      true ->
        block1 = <<b6, b5, b4, b3>>
        block2 = <<b2, b1>>
        {:ok, nvs} = File.open(@ti_nvs_file, [:binary, :read, :write])
        :file.position(nvs, 3)
        IO.binwrite(nvs, block1)
        :file.position(nvs, 10)
        IO.binwrite(nvs, block2)
        File.close(nvs) # returns :ok on success
      false -> {:error, :enoent}
    end
  end
end