• Mika Westerberg's avatar
    spi: spidev: Add ACPI probing support · cf9f4327
    Mika Westerberg authored
    Some IoT and maker software stacks are using spidev to perform raw access
    to the SPI bus instead of relying existing drivers provided by the kernel.
    They then implement their own "drivers" in userspace on top of the spidev
    raw interface. This is far from being an ideal solution but we do not want
    to prevent using mainline Linux in these devices.
    
    Now, it turns out that Windows has similar SPI devices than spidev which
    allow raw access on the SPI bus to userspace programs as described in the
    link below:
    
      https://msdn.microsoft.com/windows/hardware/drivers/spb/spi-tests-in-mitt
    
    These SPI test devices are also meant to be used during development and
    testing.
    
    In order to allow usage of spidev for development and testing in Linux, add
    those same ACPI IDs to the spidev driver (which is Linux counterpart of the
    Windows SPI test devices), but complain loudly so that users know it is not
    good idea to use it in production systems. Instead they should be using
    proper drivers for peripherals connected to the SPI bus.
    Signed-off-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
    Signed-off-by: default avatarMark Brown <broonie@kernel.org>
    cf9f4327