acpi_device: Add support for writing ACPI I2C descriptors

Add required definitions to describe an ACPI I2C bus and a method to
write the I2cSerialBus() descriptor to the SSDT.

This will be used by device drivers to describe their I2C resources to
the OS.  The devicetree i2c device can supply the address and 7 or 10
bit mode as well as indicate the GPIO controller device, and the bus
speed can be fixed or configured by the driver.

chip.h:
  struct drivers_i2c_generic_config {
    enum i2c_speed bus_speed;
  };

generic.c:
  void acpi_fill_ssdt_generator(struct device *dev) {
    struct drivers_i2c_generic_config *config = dev->chip_info;
    struct acpi_i2c i2c = {
      .address = dev->path->i2c.device,
      .mode_10bit = dev->path.i2c.mode_10bit,
      .speed = config->bus_speed ? : I2C_SPEED_FAST,
      .resource = acpi_device_path(dev->bus->dev)
    };
    ...
    acpi_device_write_i2c(&i2c);
    ...
  }

devicetree.cb:
  device pci 15.0 on
    chip drivers/i2c/generic
      device i2c 10.0 on end
    end
  end

SSDT.dsl:
  I2cSerialBus (0x10, ControllerInitiated, 400000, AddressingMode7Bit,
                "\\_SB.PCI0.I2C0", 0, ResourceConsumer)

Change-Id: I598401ac81a92c72f19da0271af1e218580a6c49
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/14935
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/src/include/device/i2c.h b/src/include/device/i2c.h
index b152bb98c2..c8c7b2283d 100644
--- a/src/include/device/i2c.h
+++ b/src/include/device/i2c.h
@@ -19,6 +19,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+enum i2c_speed {
+	I2C_SPEED_STANDARD	= 100000,
+	I2C_SPEED_FAST		= 400000,
+	I2C_SPEED_FAST_PLUS	= 1000000,
+	I2C_SPEED_HIGH		= 3400000,
+	I2C_SPEED_FAST_ULTRA	= 5000000,
+};
+
+enum i2c_address_mode {
+	I2C_MODE_7_BIT,
+	I2C_MODE_10_BIT
+};
+
 struct i2c_seg
 {
 	int read;