Merge branch 'acpi-tables'

What:		/config/acpi

Date:		July 2016

KernelVersion:	4.8

Contact:	linux-acpi@vger.kernel.org

Description:

		This represents the ACPI subsystem entry point directory. It

		contains sub-groups corresponding to ACPI configurable options.

What:		/config/acpi/table

Date:		July 2016

KernelVersion:	4.8

Description:

		This group contains the configuration for user defined ACPI

		tables. The attributes of a user define table are:

		aml 		- a binary attribute that the user can use to

				fill in the ACPI aml definitions. Once the aml

				data is written to this file and the file is

				closed the table will be loaded and ACPI devices

				will be enumerated. To check if the operation is

				successful the user must check the error code

				for close(). If the operation is successful,

				subsequent writes to this attribute will fail.

		The rest of the attributes are read-only and are valid only

		after the table has been loaded by filling the aml entry:

		signature 	- ASCII table signature

		length 		- length of table in bytes, including the header

		revision 	- ACPI Specification minor version number

		oem_id 		- ASCII OEM identification

		oem_table_id 	- ASCII OEM table identification

		oem_revision 	- OEM revision number

		asl_compiler_id - ASCII ASL compiler vendor ID

		asl_compiler_revision - ASL compiler version

In order to support ACPI open-ended hardware configurations (e.g. development

boards) we need a way to augment the ACPI configuration provided by the firmware

image. A common example is connecting sensors on I2C / SPI buses on development

boards.

Although this can be accomplished by creating a kernel platform driver or

recompiling the firmware image with updated ACPI tables, neither is practical:

the former proliferates board specific kernel code while the latter requires

access to firmware tools which are often not publicly available.

Because ACPI supports external references in AML code a more practical

way to augment firmware ACPI configuration is by dynamically loading

user defined SSDT tables that contain the board specific information.

For example, to enumerate a Bosch BMA222E accelerometer on the I2C bus of the

Minnowboard MAX development board exposed via the LSE connector [1], the

following ASL code can be used:

DefinitionBlock ("minnowmax.aml", "SSDT", 1, "Vendor", "Accel", 0x00000003)

{

    External (\_SB.I2C6, DeviceObj)

    Scope (\_SB.I2C6)

    {

        Device (STAC)

        {

            Name (_ADR, Zero)

            Name (_HID, "BMA222E")

            Method (_CRS, 0, Serialized)

            {

                Name (RBUF, ResourceTemplate ()

                {

                    I2cSerialBus (0x0018, ControllerInitiated, 0x00061A80,

                                  AddressingMode7Bit, "\\_SB.I2C6", 0x00,

                                  ResourceConsumer, ,)

                    GpioInt (Edge, ActiveHigh, Exclusive, PullDown, 0x0000,

                             "\\_SB.GPO2", 0x00, ResourceConsumer, , )

                    { // Pin list

                        0

                    }

                })

                Return (RBUF)

            }

        }

    }

}

which can then be compiled to AML binary format:

$ iasl minnowmax.asl

Intel ACPI Component Architecture

ASL Optimizing Compiler version 20140214-64 [Mar 29 2014]

Copyright (c) 2000 - 2014 Intel Corporation

ASL Input:     minnomax.asl - 30 lines, 614 bytes, 7 keywords

AML Output:    minnowmax.aml - 165 bytes, 6 named objects, 1 executable opcodes

[1] http://wiki.minnowboard.org/MinnowBoard_MAX#Low_Speed_Expansion_Connector_.28Top.29

The resulting AML code can then be loaded by the kernel using one of the methods

below.

== Loading ACPI SSDTs from initrd ==

This option allows loading of user defined SSDTs from initrd and it is useful

when the system does not support EFI or when there is not enough EFI storage.

It works in a similar way with initrd based ACPI tables override/upgrade: SSDT

aml code must be placed in the first, uncompressed, initrd under the

"kernel/firmware/acpi" path. Multiple files can be used and this will translate

in loading multiple tables. Only SSDT and OEM tables are allowed. See

initrd_table_override.txt for more details.

Here is an example:

# Add the raw ACPI tables to an uncompressed cpio archive.

# They must be put into a /kernel/firmware/acpi directory inside the

# cpio archive.

# The uncompressed cpio archive must be the first.

# Other, typically compressed cpio archives, must be

# concatenated on top of the uncompressed one.

mkdir -p kernel/firmware/acpi

cp ssdt.aml kernel/firmware/acpi

# Create the uncompressed cpio archive and concatenate the original initrd

# on top:

find kernel | cpio -H newc --create > /boot/instrumented_initrd

cat /boot/initrd >>/boot/instrumented_initrd

== Loading ACPI SSDTs from EFI variables ==

This is the preferred method, when EFI is supported on the platform, because it

allows a persistent, OS independent way of storing the user defined SSDTs. There

is also work underway to implement EFI support for loading user defined SSDTs

and using this method will make it easier to convert to the EFI loading

mechanism when that will arrive.

In order to load SSDTs from an EFI variable the efivar_ssdt kernel command line

parameter can be used. The argument for the option is the variable name to

use. If there are multiple variables with the same name but with different

vendor GUIDs, all of them will be loaded.

In order to store the AML code in an EFI variable the efivarfs filesystem can be

used. It is enabled and mounted by default in /sys/firmware/efi/efivars in all

recent distribution.

Creating a new file in /sys/firmware/efi/efivars will automatically create a new

EFI variable. Updating a file in /sys/firmware/efi/efivars will update the EFI

variable. Please note that the file name needs to be specially formatted as

"Name-GUID" and that the first 4 bytes in the file (little-endian format)

represent the attributes of the EFI variable (see EFI_VARIABLE_MASK in

include/linux/efi.h). Writing to the file must also be done with one write

operation.

For example, you can use the following bash script to create/update an EFI

variable with the content from a given file:

#!/bin/sh -e

while ! [ -z "$1" ]; do

        case "$1" in

        "-f") filename="$2"; shift;;

        "-g") guid="$2"; shift;;

        *) name="$1";;

        esac

        shift

done

usage()

{

        echo "Syntax: ${0##*/} -f filename [ -g guid ] name"

        exit 1

}

[ -n "$name" -a -f "$filename" ] || usage

EFIVARFS="/sys/firmware/efi/efivars"

[ -d "$EFIVARFS" ] || exit 2

if stat -tf $EFIVARFS | grep -q -v de5e81e4; then

        mount -t efivarfs none $EFIVARFS

fi

# try to pick up an existing GUID

[ -n "$guid" ] || guid=$(find "$EFIVARFS" -name "$name-*" | head -n1 | cut -f2- -d-)

# use a randomly generated GUID

[ -n "$guid" ] || guid="$(cat /proc/sys/kernel/random/uuid)"

# efivarfs expects all of the data in one write

tmp=$(mktemp)

/bin/echo -ne "\007\000\000\000" | cat - $filename > $tmp

dd if=$tmp of="$EFIVARFS/$name-$guid" bs=$(stat -c %s $tmp)

rm $tmp

== Loading ACPI SSDTs from configfs ==

This option allows loading of user defined SSDTs from userspace via the configfs

interface. The CONFIG_ACPI_CONFIGFS option must be select and configfs must be

mounted. In the following examples, we assume that configfs has been mounted in

/config.

New tables can be loading by creating new directories in /config/acpi/table/ and

writing the SSDT aml code in the aml attribute:

cd /config/acpi/table

mkdir my_ssdt

cat ~/ssdt.aml > my_ssdt/aml

			Address Range Mirroring feature even if your box

			doesn't support it.

	efivar_ssdt=	[EFI; X86] Name of an EFI variable that contains an SSDT

			that is to be dynamically loaded by Linux. If there are

			multiple variables with the same name but with different

			vendor GUIDs, all of them will be loaded. See

			Documentation/acpi/ssdt-overlays.txt for details.

	eisa_irq_edge=	[PARISC,HW]

			See header of drivers/parisc/eisa.c.

F:	include/acpi/

F:	Documentation/acpi/

F:	Documentation/ABI/testing/sysfs-bus-acpi

F:	Documentation/ABI/testing/configfs-acpi

F:	drivers/pci/*acpi*

F:	drivers/pci/*/*acpi*

F:	drivers/pci/*/*/*acpi*

	select ACPI_GENERIC_GSI if ACPI

	select ACPI_REDUCED_HARDWARE_ONLY if ACPI

	select ARCH_HAS_DEVMEM_IS_ALLOWED

	select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI

	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE

	select ARCH_HAS_ELF_RANDOMIZE

	select ARCH_HAS_GCOV_PROFILE_ALL