[PATCH v6 23/24] Documentation: ACPI: move ssdt-overlays.txt to admin-guide/acpi and convert to reST
Changbin Du
changbin.du at gmail.com
Fri Apr 26 01:31:16 AEST 2019
This converts the plain text documentation to reStructuredText format and
add it to Sphinx TOC tree. No essential content change.
Signed-off-by: Changbin Du <changbin.du at gmail.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung at kernel.org>
---
Documentation/acpi/ssdt-overlays.txt | 172 -----------------
Documentation/admin-guide/acpi/index.rst | 1 +
.../admin-guide/acpi/ssdt-overlays.rst | 180 ++++++++++++++++++
3 files changed, 181 insertions(+), 172 deletions(-)
delete mode 100644 Documentation/acpi/ssdt-overlays.txt
create mode 100644 Documentation/admin-guide/acpi/ssdt-overlays.rst
diff --git a/Documentation/acpi/ssdt-overlays.txt b/Documentation/acpi/ssdt-overlays.txt
deleted file mode 100644
index 5ae13f161ea2..000000000000
--- a/Documentation/acpi/ssdt-overlays.txt
+++ /dev/null
@@ -1,172 +0,0 @@
-
-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
diff --git a/Documentation/admin-guide/acpi/index.rst b/Documentation/admin-guide/acpi/index.rst
index 9049a7b9f065..4d13eeea1eca 100644
--- a/Documentation/admin-guide/acpi/index.rst
+++ b/Documentation/admin-guide/acpi/index.rst
@@ -10,4 +10,5 @@ the Linux ACPI support.
initrd_table_override
dsdt-override
+ ssdt-overlays
cppc_sysfs
diff --git a/Documentation/admin-guide/acpi/ssdt-overlays.rst b/Documentation/admin-guide/acpi/ssdt-overlays.rst
new file mode 100644
index 000000000000..da37455f96c9
--- /dev/null
+++ b/Documentation/admin-guide/acpi/ssdt-overlays.rst
@@ -0,0 +1,180 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+SSDT Overlays
+=============
+
+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
--
2.20.1
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