@callback bus_names(options :: keyword()) :: [String.t()]

Return SPI bus names on this system

No supported options

@callback info() :: map()

Return information about this backend

@callback open(bus_name :: String.t(), [Circuits.SPI.spi_option()]) ::
  {:ok, Circuits.SPI.Bus.t()} | {:error, term()}

Open a SPI bus device

On success, open/2 returns a reference that may be passed to with transfer/2. The device will be closed automatically when the reference goes out of scope.

SPI is not a standardized interface so appropriate options will different from device-to-device. The defaults use here work on many devices.

Parameters:

• bus_name is the name of the bus (e.g., "spidev0.0"). See bus_names/0
• opts is a keyword list to configure the bus