acpi_device: Add support for writing ACPI SPI descriptors

Add required definitions to describe an ACPI SPI bus and a method to
write the SpiSerialBus() descriptor to the SSDT.

This will be used by device drivers to describe their SPI resources to
the OS.  SPI devices are not currently enumerated in the devicetree but
can be enumerated by device drivers directly.

generic.c:
  void acpi_fill_ssdt_generator(struct device *dev) {
    struct acpi_spi spi = {
      .device_select = dev->path->generic.device.id,
      .device_select_polarity = SPI_POLARITY_LOW,
      .spi_wire_mode = SPI_4_WIRE_MODE,
      .speed = 1000 * 1000; /* 1 mHz */
      .data_bit_length = 8,
      .clock_phase = SPI_CLOCK_PHASE_FIRST,
      .clock_polarity = SPI_POLARITY_LOW,
      .resource = acpi_device_path(dev->bus->dev)
    };
    ...
    acpi_device_write_spi(&spi);
    ...
  }

devicetree.cb:
  device pci 1e.2 on
    chip drivers/spi/generic
      device generic 0 on end
    end
  end

SSDT.dsl:
  SpiSerialBus (0, PolarityLow, FourWireMode, 8, ControllerInitiated,
                1000000, ClockPolarityLow, ClockPhaseFirst,
                "\\_SB.PCI0.SPI0", 0, ResourceConsumer)

Change-Id: I0ef83dc111ac6c19d68872ab64e1e5e3a7756cae
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/14936
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

0 files changed, 0 insertions, 0 deletions