device: Add an ACPI device name and path concept to devices

Hardware / Coreboot - Duncan Laurie [chromium.org] - 20 May 2016 22:59 UTC

Add a function to "struct device_operations" to return the ACPI name for the device, and helper functions to find this name (either from the device or its parent) and to build a fully qualified ACPI path from the root device.

This addition will allow device drivers to generate their ACPI AML in the SSDT at boot, with customization supplied by devicetree.cb, instead of needing custom DSDT ASL for every mainboard.

The root device acpi_name is defined as "\\_SB" and is used to start the path when building a fully qualified name.

This requires SOC support to provide handlers for returning the ACPI name for devices that it owns, and those names must match the objects declared in the DSDT. The handler can be done either in each device driver or with a global handler for the entire SOC.

Simplified example of how this can be used for an i2c device declared in devicetree.cb with:

chip soc/intel/skylake # "\_SB" (from root device) device domain 0 on # "PCI0" device pci 19.2 on # "I2C4" chip drivers/i2c/test0 device i2c 1a.0 on end # "TST0" end end end end

And basic SSDT generating code in the device driver:

acpigen_write_scope(acpi_device_scope(dev)); acpigen_write_device(acpi_device_name(dev)); acpigen_write_string("_HID", "TEST0000"); acpigen_write_byte("_UID", 0); acpigen_pop_len(); /* device */ acpigen_pop_len(); /* scope */

Will produce this ACPI code:

Scope (\_SB.PCI0.I2C4) { Device (TST0) { Name (_HID, "TEST0000") Name (_UID, 0) } }

Change-Id: Ie149595aeab96266fa5f006e7934339f0119ac54

d9af3ce device: Add an ACPI device name and path concept to devices
src/arch/x86/Makefile.inc | 1 +
src/arch/x86/acpi_device.c | 111 +++++++++++++++++++++++++++++++
src/arch/x86/include/arch/acpi_device.h | 25 +++++++
src/device/root_device.c | 10 +++
src/include/device/device.h | 1 +
5 files changed, 148 insertions(+)

Upstream: review.coreboot.org

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