sravan/system76-coreboot
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

acpi_device: Add support for writing ACPI I2C descriptors

Browse Source 
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>
This commit is contained in:
Duncan Laurie
2016-05-09 20:10:47 -07:00
committed by Duncan Laurie
parent cfb6ea7e65
commit 1010b4aeac
3 changed files with 98 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

58
src/arch/x86/acpi_device.c
View File

@@ -18,6 +18,7 @@
#include <arch/acpi_device.h>
#include <arch/acpigen.h>
#include <device/device.h>
#include <device/i2c.h>
#include <device/path.h>
#if IS_ENABLED(CONFIG_GENERIC_GPIO_LIB)
#include <gpio.h>
@@ -323,3 +324,60 @@ void acpi_device_write_gpio(const struct acpi_gpio *gpio)
/* Fill in GPIO Descriptor Length (account for len word) */
acpi_device_fill_len(desc_length);
}
/* ACPI 6.1 section 6.4.3.8.2.1 - I2cSerialBus() */
void acpi_device_write_i2c(const struct acpi_i2c *i2c)
{
void *desc_length, *type_length;
/* Byte 0: Descriptor Type */
acpigen_emit_byte(ACPI_DESCRIPTOR_SERIAL_BUS);
/* Byte 1+2: Length (filled in later) */
desc_length = acpi_device_write_zero_len();
/* Byte 3: Revision ID */
acpigen_emit_byte(ACPI_SERIAL_BUS_REVISION_ID);
/* Byte 4: Resource Source Index is Reserved */
acpigen_emit_byte(0);
/* Byte 5: Serial Bus Type is I2C */
acpigen_emit_byte(ACPI_SERIAL_BUS_TYPE_I2C);
/*
* Byte 6: Flags
* [7:2]: 0 => Reserved
* [1]: 1 => ResourceConsumer
* [0]: 0 => ControllerInitiated
*/
acpigen_emit_byte(1 << 1);
/*
* Byte 7-8: Type Specific Flags
* [15:1]: 0 => Reserved
* [0]: 0 => 7bit, 1 => 10bit
*/
acpigen_emit_word(i2c->mode_10bit);
/* Byte 9: Type Specific Revision ID */
acpigen_emit_byte(ACPI_SERIAL_BUS_REVISION_ID);
/* Byte 10-11: I2C Type Data Length */
type_length = acpi_device_write_zero_len();
/* Byte 12-15: I2C Bus Speed */
acpigen_emit_dword(i2c->speed);
/* Byte 16-17: I2C Slave Address */
acpigen_emit_word(i2c->address);
/* Fill in Type Data Length */
acpi_device_fill_len(type_length);
/* Byte 18+: ResourceSource */
acpigen_emit_string(i2c->resource);
/* Fill in I2C Descriptor Length */
acpi_device_fill_len(desc_length);
}