Documentation: ACPI: move namespace.txt to firmware-guide/acpi and convert to reST
This converts the plain text documentation to reStructuredText format and adds it to Sphinx TOC tree. No essential content change. Signed-off-by: Changbin Du <changbin.du@gmail.com> Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Changbin Du
Rafael J. Wysocki
Родитель
680e6ffa15
Коммит
8a2fe04b44
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@ -7,3 +7,4 @@ ACPI Support
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.. toctree::
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:maxdepth: 1
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namespace
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@ -1,26 +1,29 @@
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.. SPDX-License-Identifier: GPL-2.0
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.. include:: <isonum.txt>
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===================================================
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ACPI Device Tree - Representation of ACPI Namespace
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===================================================
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Copyright (C) 2013, Intel Corporation
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Author: Lv Zheng <lv.zheng@intel.com>
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:Copyright: |copy| 2013, Intel Corporation
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:Author: Lv Zheng <lv.zheng@intel.com>
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Abstract:
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:Credit: Thanks for the help from Zhang Rui <rui.zhang@intel.com> and
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Rafael J.Wysocki <rafael.j.wysocki@intel.com>.
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Abstract
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========
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The Linux ACPI subsystem converts ACPI namespace objects into a Linux
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device tree under the /sys/devices/LNXSYSTEM:00 and updates it upon
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receiving ACPI hotplug notification events. For each device object in this
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hierarchy there is a corresponding symbolic link in the
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receiving ACPI hotplug notification events. For each device object
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in this hierarchy there is a corresponding symbolic link in the
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/sys/bus/acpi/devices.
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This document illustrates the structure of the ACPI device tree.
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Credit:
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Thanks for the help from Zhang Rui <rui.zhang@intel.com> and Rafael J.
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Wysocki <rafael.j.wysocki@intel.com>.
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1. ACPI Definition Blocks
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ACPI Definition Blocks
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======================
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The ACPI firmware sets up RSDP (Root System Description Pointer) in the
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system memory address space pointing to the XSDT (Extended System
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@ -40,7 +43,7 @@ Wysocki <rafael.j.wysocki@intel.com>.
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structure of the underlying hardware platform.
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The relationships between ACPI System Definition Tables described above
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are illustrated in the following diagram.
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are illustrated in the following diagram::
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+---------+ +-------+ +--------+ +------------------------+
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| RSDP | +->| XSDT | +->| FADT | | +-------------------+ |
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@ -68,18 +71,20 @@ Wysocki <rafael.j.wysocki@intel.com>.
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Figure 1. ACPI Definition Blocks
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NOTE: RSDP can also contain a pointer to the RSDT (Root System
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.. note:: RSDP can also contain a pointer to the RSDT (Root System
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Description Table). Platforms provide RSDT to enable
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compatibility with ACPI 1.0 operating systems. The OS is expected
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to use XSDT, if present.
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2. Example ACPI Namespace
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Example ACPI Namespace
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======================
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All definition blocks are loaded into a single namespace. The namespace
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is a hierarchy of objects identified by names and paths.
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The following naming conventions apply to object names in the ACPI
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namespace:
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1. All names are 32 bits long.
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2. The first byte of a name must be one of 'A' - 'Z', '_'.
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3. Each of the remaining bytes of a name must be one of 'A' - 'Z', '0'
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@ -91,7 +96,7 @@ Wysocki <rafael.j.wysocki@intel.com>.
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(i.e. names prepended with '^' are relative to the parent of the
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current namespace node).
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The figure below shows an example ACPI namespace.
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The figure below shows an example ACPI namespace::
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+------+
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| \ | Root
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@ -184,7 +189,8 @@ Wysocki <rafael.j.wysocki@intel.com>.
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Figure 2. Example ACPI Namespace
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3. Linux ACPI Device Objects
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Linux ACPI Device Objects
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=========================
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The Linux kernel's core ACPI subsystem creates struct acpi_device
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objects for ACPI namespace objects representing devices, power resources
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@ -196,7 +202,7 @@ Wysocki <rafael.j.wysocki@intel.com>.
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two-digit decimal representation of an unsigned integer).
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The value of 'bus_id' depends on the type of the object whose name it is
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part of as listed in the table below.
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part of as listed in the table below::
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+---+-----------------+-------+----------+
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| | Object/Feature | Table | bus_id |
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@ -230,6 +236,7 @@ Wysocki <rafael.j.wysocki@intel.com>.
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the basis of the contents of ACPI System Description Tables (as
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indicated by the letter in the first column and the notation in the
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second column of the table above):
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N:
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The object's source is an ACPI namespace node (as indicated by the
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named object's type in the second column). In that case the object's
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@ -256,6 +263,7 @@ Wysocki <rafael.j.wysocki@intel.com>.
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The forth column of the above table indicates the 'bus_id' generation
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rule of the struct acpi_device object:
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_HID:
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_HID in the last column of the table means that the object's bus_id
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is derived from the _HID/_CID identification objects present under
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@ -275,7 +283,8 @@ Wysocki <rafael.j.wysocki@intel.com>.
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object's bus_id.
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4. Linux ACPI Physical Device Glue
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Linux ACPI Physical Device Glue
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===============================
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ACPI device (i.e. struct acpi_device) objects may be linked to other
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objects in the Linux' device hierarchy that represent "physical" devices
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@ -309,11 +318,12 @@ Wysocki <rafael.j.wysocki@intel.com>.
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drivers/pci/pci-acpi.c.
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5. Example Linux ACPI Device Tree
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Example Linux ACPI Device Tree
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=================================
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The sysfs hierarchy of struct acpi_device objects corresponding to the
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example ACPI namespace illustrated in Figure 2 with the addition of
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fixed PWR_BUTTON/SLP_BUTTON devices is shown below.
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fixed PWR_BUTTON/SLP_BUTTON devices is shown below::
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+--------------+---+-----------------+
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| LNXSYSTEM:00 | \ | acpi:LNXSYSTEM: |
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@ -377,12 +387,14 @@ Wysocki <rafael.j.wysocki@intel.com>.
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Figure 3. Example Linux ACPI Device Tree
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NOTE: Each node is represented as "object/path/modalias", where:
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.. note:: Each node is represented as "object/path/modalias", where:
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1. 'object' is the name of the object's directory in sysfs.
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2. 'path' is the ACPI namespace path of the corresponding
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ACPI namespace object, as returned by the object's 'path'
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sysfs attribute.
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3. 'modalias' is the value of the object's 'modalias' sysfs
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attribute (as described earlier in this document).
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NOTE: N/A indicates the device object does not have the 'path' or the
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.. note:: N/A indicates the device object does not have the 'path' or the
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'modalias' attribute.
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