[PATCH v5 01/23] Documentation: ACPI: move namespace.txt to firmware-guide/acpi and convert to reST
Changbin Du
changbin.du at gmail.com
Thu Apr 25 03:52:44 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/firmware-guide/acpi/index.rst | 1 +
.../acpi/namespace.rst} | 294 +++++++++---------
2 files changed, 154 insertions(+), 141 deletions(-)
rename Documentation/{acpi/namespace.txt => firmware-guide/acpi/namespace.rst} (56%)
diff --git a/Documentation/firmware-guide/acpi/index.rst b/Documentation/firmware-guide/acpi/index.rst
index 0ec7d072ba22..210ad8acd6df 100644
--- a/Documentation/firmware-guide/acpi/index.rst
+++ b/Documentation/firmware-guide/acpi/index.rst
@@ -7,3 +7,4 @@ ACPI Support
.. toctree::
:maxdepth: 1
+ namespace
diff --git a/Documentation/acpi/namespace.txt b/Documentation/firmware-guide/acpi/namespace.rst
similarity index 56%
rename from Documentation/acpi/namespace.txt
rename to Documentation/firmware-guide/acpi/namespace.rst
index 1860cb3865c6..835521baeb89 100644
--- a/Documentation/acpi/namespace.txt
+++ b/Documentation/firmware-guide/acpi/namespace.rst
@@ -1,85 +1,90 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+===================================================
ACPI Device Tree - Representation of ACPI Namespace
+===================================================
-Copyright (C) 2013, Intel Corporation
-Author: Lv Zheng <lv.zheng at intel.com>
+:Copyright: |copy| 2013, Intel Corporation
+:Author: Lv Zheng <lv.zheng at intel.com>
-Abstract:
+:Credit: Thanks for the help from Zhang Rui <rui.zhang at intel.com> and
+ Rafael J.Wysocki <rafael.j.wysocki at intel.com>.
+Abstract
+========
The Linux ACPI subsystem converts ACPI namespace objects into a Linux
device tree under the /sys/devices/LNXSYSTEM:00 and updates it upon
-receiving ACPI hotplug notification events. For each device object in this
-hierarchy there is a corresponding symbolic link in the
+receiving ACPI hotplug notification events. For each device object
+in this hierarchy there is a corresponding symbolic link in the
/sys/bus/acpi/devices.
+
This document illustrates the structure of the ACPI device tree.
+ACPI Definition Blocks
+======================
+
+The ACPI firmware sets up RSDP (Root System Description Pointer) in the
+system memory address space pointing to the XSDT (Extended System
+Description Table). The XSDT always points to the FADT (Fixed ACPI
+Description Table) using its first entry, the data within the FADT
+includes various fixed-length entries that describe fixed ACPI features
+of the hardware. The FADT contains a pointer to the DSDT
+(Differentiated System Descripition Table). The XSDT also contains
+entries pointing to possibly multiple SSDTs (Secondary System
+Description Table).
+
+The DSDT and SSDT data is organized in data structures called definition
+blocks that contain definitions of various objects, including ACPI
+control methods, encoded in AML (ACPI Machine Language). The data block
+of the DSDT along with the contents of SSDTs represents a hierarchical
+data structure called the ACPI namespace whose topology reflects the
+structure of the underlying hardware platform.
+
+The relationships between ACPI System Definition Tables described above
+are illustrated in the following diagram::
+
+ +---------+ +-------+ +--------+ +------------------------+
+ | RSDP | +->| XSDT | +->| FADT | | +-------------------+ |
+ +---------+ | +-------+ | +--------+ +-|->| DSDT | |
+ | Pointer | | | Entry |-+ | ...... | | | +-------------------+ |
+ +---------+ | +-------+ | X_DSDT |--+ | | Definition Blocks | |
+ | Pointer |-+ | ..... | | ...... | | +-------------------+ |
+ +---------+ +-------+ +--------+ | +-------------------+ |
+ | Entry |------------------|->| SSDT | |
+ +- - - -+ | +-------------------| |
+ | Entry | - - - - - - - -+ | | Definition Blocks | |
+ +- - - -+ | | +-------------------+ |
+ | | +- - - - - - - - - -+ |
+ +-|->| SSDT | |
+ | +-------------------+ |
+ | | Definition Blocks | |
+ | +- - - - - - - - - -+ |
+ +------------------------+
+ |
+ OSPM Loading |
+ \|/
+ +----------------+
+ | ACPI Namespace |
+ +----------------+
+
+ Figure 1. ACPI Definition Blocks
+
+.. note:: RSDP can also contain a pointer to the RSDT (Root System
+ Description Table). Platforms provide RSDT to enable
+ compatibility with ACPI 1.0 operating systems. The OS is expected
+ to use XSDT, if present.
+
+
+Example ACPI Namespace
+======================
+
+All definition blocks are loaded into a single namespace. The namespace
+is a hierarchy of objects identified by names and paths.
+The following naming conventions apply to object names in the ACPI
+namespace:
-Credit:
-
-Thanks for the help from Zhang Rui <rui.zhang at intel.com> and Rafael J.
-Wysocki <rafael.j.wysocki at intel.com>.
-
-
-1. ACPI Definition Blocks
-
- The ACPI firmware sets up RSDP (Root System Description Pointer) in the
- system memory address space pointing to the XSDT (Extended System
- Description Table). The XSDT always points to the FADT (Fixed ACPI
- Description Table) using its first entry, the data within the FADT
- includes various fixed-length entries that describe fixed ACPI features
- of the hardware. The FADT contains a pointer to the DSDT
- (Differentiated System Descripition Table). The XSDT also contains
- entries pointing to possibly multiple SSDTs (Secondary System
- Description Table).
-
- The DSDT and SSDT data is organized in data structures called definition
- blocks that contain definitions of various objects, including ACPI
- control methods, encoded in AML (ACPI Machine Language). The data block
- of the DSDT along with the contents of SSDTs represents a hierarchical
- data structure called the ACPI namespace whose topology reflects the
- structure of the underlying hardware platform.
-
- The relationships between ACPI System Definition Tables described above
- are illustrated in the following diagram.
-
- +---------+ +-------+ +--------+ +------------------------+
- | RSDP | +->| XSDT | +->| FADT | | +-------------------+ |
- +---------+ | +-------+ | +--------+ +-|->| DSDT | |
- | Pointer | | | Entry |-+ | ...... | | | +-------------------+ |
- +---------+ | +-------+ | X_DSDT |--+ | | Definition Blocks | |
- | Pointer |-+ | ..... | | ...... | | +-------------------+ |
- +---------+ +-------+ +--------+ | +-------------------+ |
- | Entry |------------------|->| SSDT | |
- +- - - -+ | +-------------------| |
- | Entry | - - - - - - - -+ | | Definition Blocks | |
- +- - - -+ | | +-------------------+ |
- | | +- - - - - - - - - -+ |
- +-|->| SSDT | |
- | +-------------------+ |
- | | Definition Blocks | |
- | +- - - - - - - - - -+ |
- +------------------------+
- |
- OSPM Loading |
- \|/
- +----------------+
- | ACPI Namespace |
- +----------------+
-
- Figure 1. ACPI Definition Blocks
-
- NOTE: RSDP can also contain a pointer to the RSDT (Root System
- Description Table). Platforms provide RSDT to enable
- compatibility with ACPI 1.0 operating systems. The OS is expected
- to use XSDT, if present.
-
-
-2. Example ACPI Namespace
-
- All definition blocks are loaded into a single namespace. The namespace
- is a hierarchy of objects identified by names and paths.
- The following naming conventions apply to object names in the ACPI
- namespace:
1. All names are 32 bits long.
2. The first byte of a name must be one of 'A' - 'Z', '_'.
3. Each of the remaining bytes of a name must be one of 'A' - 'Z', '0'
@@ -91,7 +96,7 @@ Wysocki <rafael.j.wysocki at intel.com>.
(i.e. names prepended with '^' are relative to the parent of the
current namespace node).
- The figure below shows an example ACPI namespace.
+The figure below shows an example ACPI namespace::
+------+
| \ | Root
@@ -184,19 +189,20 @@ Wysocki <rafael.j.wysocki at intel.com>.
Figure 2. Example ACPI Namespace
-3. Linux ACPI Device Objects
+Linux ACPI Device Objects
+=========================
- The Linux kernel's core ACPI subsystem creates struct acpi_device
- objects for ACPI namespace objects representing devices, power resources
- processors, thermal zones. Those objects are exported to user space via
- sysfs as directories in the subtree under /sys/devices/LNXSYSTM:00. The
- format of their names is <bus_id:instance>, where 'bus_id' refers to the
- ACPI namespace representation of the given object and 'instance' is used
- for distinguishing different object of the same 'bus_id' (it is
- two-digit decimal representation of an unsigned integer).
+The Linux kernel's core ACPI subsystem creates struct acpi_device
+objects for ACPI namespace objects representing devices, power resources
+processors, thermal zones. Those objects are exported to user space via
+sysfs as directories in the subtree under /sys/devices/LNXSYSTM:00. The
+format of their names is <bus_id:instance>, where 'bus_id' refers to the
+ACPI namespace representation of the given object and 'instance' is used
+for distinguishing different object of the same 'bus_id' (it is
+two-digit decimal representation of an unsigned integer).
- The value of 'bus_id' depends on the type of the object whose name it is
- part of as listed in the table below.
+The value of 'bus_id' depends on the type of the object whose name it is
+part of as listed in the table below::
+---+-----------------+-------+----------+
| | Object/Feature | Table | bus_id |
@@ -226,10 +232,11 @@ Wysocki <rafael.j.wysocki at intel.com>.
Table 1. ACPI Namespace Objects Mapping
- The following rules apply when creating struct acpi_device objects on
- the basis of the contents of ACPI System Description Tables (as
- indicated by the letter in the first column and the notation in the
- second column of the table above):
+The following rules apply when creating struct acpi_device objects on
+the basis of the contents of ACPI System Description Tables (as
+indicated by the letter in the first column and the notation in the
+second column of the table above):
+
N:
The object's source is an ACPI namespace node (as indicated by the
named object's type in the second column). In that case the object's
@@ -249,13 +256,14 @@ Wysocki <rafael.j.wysocki at intel.com>.
struct acpi_device object with LNXVIDEO 'bus_id' will be created for
it.
- The third column of the above table indicates which ACPI System
- Description Tables contain information used for the creation of the
- struct acpi_device objects represented by the given row (xSDT means DSDT
- or SSDT).
+The third column of the above table indicates which ACPI System
+Description Tables contain information used for the creation of the
+struct acpi_device objects represented by the given row (xSDT means DSDT
+or SSDT).
+
+The forth column of the above table indicates the 'bus_id' generation
+rule of the struct acpi_device object:
- The forth column of the above table indicates the 'bus_id' generation
- rule of the struct acpi_device object:
_HID:
_HID in the last column of the table means that the object's bus_id
is derived from the _HID/_CID identification objects present under
@@ -275,45 +283,47 @@ Wysocki <rafael.j.wysocki at intel.com>.
object's bus_id.
-4. Linux ACPI Physical Device Glue
-
- ACPI device (i.e. struct acpi_device) objects may be linked to other
- objects in the Linux' device hierarchy that represent "physical" devices
- (for example, devices on the PCI bus). If that happens, it means that
- the ACPI device object is a "companion" of a device otherwise
- represented in a different way and is used (1) to provide configuration
- information on that device which cannot be obtained by other means and
- (2) to do specific things to the device with the help of its ACPI
- control methods. One ACPI device object may be linked this way to
- multiple "physical" devices.
-
- If an ACPI device object is linked to a "physical" device, its sysfs
- directory contains the "physical_node" symbolic link to the sysfs
- directory of the target device object. In turn, the target device's
- sysfs directory will then contain the "firmware_node" symbolic link to
- the sysfs directory of the companion ACPI device object.
- The linking mechanism relies on device identification provided by the
- ACPI namespace. For example, if there's an ACPI namespace object
- representing a PCI device (i.e. a device object under an ACPI namespace
- object representing a PCI bridge) whose _ADR returns 0x00020000 and the
- bus number of the parent PCI bridge is 0, the sysfs directory
- representing the struct acpi_device object created for that ACPI
- namespace object will contain the 'physical_node' symbolic link to the
- /sys/devices/pci0000:00/0000:00:02:0/ sysfs directory of the
- corresponding PCI device.
-
- The linking mechanism is generally bus-specific. The core of its
- implementation is located in the drivers/acpi/glue.c file, but there are
- complementary parts depending on the bus types in question located
- elsewhere. For example, the PCI-specific part of it is located in
- drivers/pci/pci-acpi.c.
-
-
-5. Example Linux ACPI Device Tree
-
- The sysfs hierarchy of struct acpi_device objects corresponding to the
- example ACPI namespace illustrated in Figure 2 with the addition of
- fixed PWR_BUTTON/SLP_BUTTON devices is shown below.
+Linux ACPI Physical Device Glue
+===============================
+
+ACPI device (i.e. struct acpi_device) objects may be linked to other
+objects in the Linux' device hierarchy that represent "physical" devices
+(for example, devices on the PCI bus). If that happens, it means that
+the ACPI device object is a "companion" of a device otherwise
+represented in a different way and is used (1) to provide configuration
+information on that device which cannot be obtained by other means and
+(2) to do specific things to the device with the help of its ACPI
+control methods. One ACPI device object may be linked this way to
+multiple "physical" devices.
+
+If an ACPI device object is linked to a "physical" device, its sysfs
+directory contains the "physical_node" symbolic link to the sysfs
+directory of the target device object. In turn, the target device's
+sysfs directory will then contain the "firmware_node" symbolic link to
+the sysfs directory of the companion ACPI device object.
+The linking mechanism relies on device identification provided by the
+ACPI namespace. For example, if there's an ACPI namespace object
+representing a PCI device (i.e. a device object under an ACPI namespace
+object representing a PCI bridge) whose _ADR returns 0x00020000 and the
+bus number of the parent PCI bridge is 0, the sysfs directory
+representing the struct acpi_device object created for that ACPI
+namespace object will contain the 'physical_node' symbolic link to the
+/sys/devices/pci0000:00/0000:00:02:0/ sysfs directory of the
+corresponding PCI device.
+
+The linking mechanism is generally bus-specific. The core of its
+implementation is located in the drivers/acpi/glue.c file, but there are
+complementary parts depending on the bus types in question located
+elsewhere. For example, the PCI-specific part of it is located in
+drivers/pci/pci-acpi.c.
+
+
+Example Linux ACPI Device Tree
+=================================
+
+The sysfs hierarchy of struct acpi_device objects corresponding to the
+example ACPI namespace illustrated in Figure 2 with the addition of
+fixed PWR_BUTTON/SLP_BUTTON devices is shown below::
+--------------+---+-----------------+
| LNXSYSTEM:00 | \ | acpi:LNXSYSTEM: |
@@ -377,12 +387,14 @@ Wysocki <rafael.j.wysocki at intel.com>.
Figure 3. Example Linux ACPI Device Tree
- NOTE: Each node is represented as "object/path/modalias", where:
- 1. 'object' is the name of the object's directory in sysfs.
- 2. 'path' is the ACPI namespace path of the corresponding
- ACPI namespace object, as returned by the object's 'path'
- sysfs attribute.
- 3. 'modalias' is the value of the object's 'modalias' sysfs
- attribute (as described earlier in this document).
- NOTE: N/A indicates the device object does not have the 'path' or the
- 'modalias' attribute.
+.. note:: Each node is represented as "object/path/modalias", where:
+
+ 1. 'object' is the name of the object's directory in sysfs.
+ 2. 'path' is the ACPI namespace path of the corresponding
+ ACPI namespace object, as returned by the object's 'path'
+ sysfs attribute.
+ 3. 'modalias' is the value of the object's 'modalias' sysfs
+ attribute (as described earlier in this document).
+
+.. note:: N/A indicates the device object does not have the 'path' or the
+ 'modalias' attribute.
--
2.20.1
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