summaryrefslogtreecommitdiffstats
path: root/Documentation/driver-api/acpi
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--Documentation/driver-api/acpi/index.rst9
-rw-r--r--Documentation/driver-api/acpi/linuxized-acpica.rst279
-rw-r--r--Documentation/driver-api/acpi/scan_handlers.rst83
3 files changed, 371 insertions, 0 deletions
diff --git a/Documentation/driver-api/acpi/index.rst b/Documentation/driver-api/acpi/index.rst
new file mode 100644
index 000000000..ace0008e5
--- /dev/null
+++ b/Documentation/driver-api/acpi/index.rst
@@ -0,0 +1,9 @@
+============
+ACPI Support
+============
+
+.. toctree::
+ :maxdepth: 2
+
+ linuxized-acpica
+ scan_handlers
diff --git a/Documentation/driver-api/acpi/linuxized-acpica.rst b/Documentation/driver-api/acpi/linuxized-acpica.rst
new file mode 100644
index 000000000..6bee03383
--- /dev/null
+++ b/Documentation/driver-api/acpi/linuxized-acpica.rst
@@ -0,0 +1,279 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+============================================================
+Linuxized ACPICA - Introduction to ACPICA Release Automation
+============================================================
+
+:Copyright: |copy| 2013-2016, Intel Corporation
+
+:Author: Lv Zheng <lv.zheng@intel.com>
+
+
+Abstract
+========
+This document describes the ACPICA project and the relationship between
+ACPICA and Linux. It also describes how ACPICA code in drivers/acpi/acpica,
+include/acpi and tools/power/acpi is automatically updated to follow the
+upstream.
+
+ACPICA Project
+==============
+
+The ACPI Component Architecture (ACPICA) project provides an operating
+system (OS)-independent reference implementation of the Advanced
+Configuration and Power Interface Specification (ACPI). It has been
+adapted by various host OSes. By directly integrating ACPICA, Linux can
+also benefit from the application experiences of ACPICA from other host
+OSes.
+
+The homepage of ACPICA project is: www.acpica.org, it is maintained and
+supported by Intel Corporation.
+
+The following figure depicts the Linux ACPI subsystem where the ACPICA
+adaptation is included::
+
+ +---------------------------------------------------------+
+ | |
+ | +---------------------------------------------------+ |
+ | | +------------------+ | |
+ | | | Table Management | | |
+ | | +------------------+ | |
+ | | +----------------------+ | |
+ | | | Namespace Management | | |
+ | | +----------------------+ | |
+ | | +------------------+ ACPICA Components | |
+ | | | Event Management | | |
+ | | +------------------+ | |
+ | | +---------------------+ | |
+ | | | Resource Management | | |
+ | | +---------------------+ | |
+ | | +---------------------+ | |
+ | | | Hardware Management | | |
+ | | +---------------------+ | |
+ | +---------------------------------------------------+ | |
+ | | | +------------------+ | | |
+ | | | | OS Service Layer | | | |
+ | | | +------------------+ | | |
+ | | +-------------------------------------------------|-+ |
+ | | +--------------------+ | |
+ | | | Device Enumeration | | |
+ | | +--------------------+ | |
+ | | +------------------+ | |
+ | | | Power Management | | |
+ | | +------------------+ Linux/ACPI Components | |
+ | | +--------------------+ | |
+ | | | Thermal Management | | |
+ | | +--------------------+ | |
+ | | +--------------------------+ | |
+ | | | Drivers for ACPI Devices | | |
+ | | +--------------------------+ | |
+ | | +--------+ | |
+ | | | ...... | | |
+ | | +--------+ | |
+ | +---------------------------------------------------+ |
+ | |
+ +---------------------------------------------------------+
+
+ Figure 1. Linux ACPI Software Components
+
+.. note::
+ A. OS Service Layer - Provided by Linux to offer OS dependent
+ implementation of the predefined ACPICA interfaces (acpi_os_*).
+ ::
+
+ include/acpi/acpiosxf.h
+ drivers/acpi/osl.c
+ include/acpi/platform
+ include/asm/acenv.h
+ B. ACPICA Functionality - Released from ACPICA code base to offer
+ OS independent implementation of the ACPICA interfaces (acpi_*).
+ ::
+
+ drivers/acpi/acpica
+ include/acpi/ac*.h
+ tools/power/acpi
+ C. Linux/ACPI Functionality - Providing Linux specific ACPI
+ functionality to the other Linux kernel subsystems and user space
+ programs.
+ ::
+
+ drivers/acpi
+ include/linux/acpi.h
+ include/linux/acpi*.h
+ include/acpi
+ tools/power/acpi
+ D. Architecture Specific ACPICA/ACPI Functionalities - Provided by the
+ ACPI subsystem to offer architecture specific implementation of the
+ ACPI interfaces. They are Linux specific components and are out of
+ the scope of this document.
+ ::
+
+ include/asm/acpi.h
+ include/asm/acpi*.h
+ arch/*/acpi
+
+ACPICA Release
+==============
+
+The ACPICA project maintains its code base at the following repository URL:
+https://github.com/acpica/acpica.git. As a rule, a release is made every
+month.
+
+As the coding style adopted by the ACPICA project is not acceptable by
+Linux, there is a release process to convert the ACPICA git commits into
+Linux patches. The patches generated by this process are referred to as
+"linuxized ACPICA patches". The release process is carried out on a local
+copy the ACPICA git repository. Each commit in the monthly release is
+converted into a linuxized ACPICA patch. Together, they form the monthly
+ACPICA release patchset for the Linux ACPI community. This process is
+illustrated in the following figure::
+
+ +-----------------------------+
+ | acpica / master (-) commits |
+ +-----------------------------+
+ /|\ |
+ | \|/
+ | /---------------------\ +----------------------+
+ | < Linuxize repo Utility >-->| old linuxized acpica |--+
+ | \---------------------/ +----------------------+ |
+ | |
+ /---------\ |
+ < git reset > \
+ \---------/ \
+ /|\ /+-+
+ | / |
+ +-----------------------------+ | |
+ | acpica / master (+) commits | | |
+ +-----------------------------+ | |
+ | | |
+ \|/ | |
+ /-----------------------\ +----------------------+ | |
+ < Linuxize repo Utilities >-->| new linuxized acpica |--+ |
+ \-----------------------/ +----------------------+ |
+ \|/
+ +--------------------------+ /----------------------\
+ | Linuxized ACPICA Patches |<----------------< Linuxize patch Utility >
+ +--------------------------+ \----------------------/
+ |
+ \|/
+ /---------------------------\
+ < Linux ACPI Community Review >
+ \---------------------------/
+ |
+ \|/
+ +-----------------------+ /------------------\ +----------------+
+ | linux-pm / linux-next |-->< Linux Merge Window >-->| linux / master |
+ +-----------------------+ \------------------/ +----------------+
+
+ Figure 2. ACPICA -> Linux Upstream Process
+
+.. note::
+ A. Linuxize Utilities - Provided by the ACPICA repository, including a
+ utility located in source/tools/acpisrc folder and a number of
+ scripts located in generate/linux folder.
+ B. acpica / master - "master" branch of the git repository at
+ <https://github.com/acpica/acpica.git>.
+ C. linux-pm / linux-next - "linux-next" branch of the git repository at
+ <https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git>.
+ D. linux / master - "master" branch of the git repository at
+ <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git>.
+
+ Before the linuxized ACPICA patches are sent to the Linux ACPI community
+ for review, there is a quality assurance build test process to reduce
+ porting issues. Currently this build process only takes care of the
+ following kernel configuration options:
+ CONFIG_ACPI/CONFIG_ACPI_DEBUG/CONFIG_ACPI_DEBUGGER
+
+ACPICA Divergences
+==================
+
+Ideally, all of the ACPICA commits should be converted into Linux patches
+automatically without manual modifications, the "linux / master" tree should
+contain the ACPICA code that exactly corresponds to the ACPICA code
+contained in "new linuxized acpica" tree and it should be possible to run
+the release process fully automatically.
+
+As a matter of fact, however, there are source code differences between
+the ACPICA code in Linux and the upstream ACPICA code, referred to as
+"ACPICA Divergences".
+
+The various sources of ACPICA divergences include:
+ 1. Legacy divergences - Before the current ACPICA release process was
+ established, there already had been divergences between Linux and
+ ACPICA. Over the past several years those divergences have been greatly
+ reduced, but there still are several ones and it takes time to figure
+ out the underlying reasons for their existence.
+ 2. Manual modifications - Any manual modification (eg. coding style fixes)
+ made directly in the Linux sources obviously hurts the ACPICA release
+ automation. Thus it is recommended to fix such issues in the ACPICA
+ upstream source code and generate the linuxized fix using the ACPICA
+ release utilities (please refer to Section 4 below for the details).
+ 3. Linux specific features - Sometimes it's impossible to use the
+ current ACPICA APIs to implement features required by the Linux kernel,
+ so Linux developers occasionally have to change ACPICA code directly.
+ Those changes may not be acceptable by ACPICA upstream and in such cases
+ they are left as committed ACPICA divergences unless the ACPICA side can
+ implement new mechanisms as replacements for them.
+ 4. ACPICA release fixups - ACPICA only tests commits using a set of the
+ user space simulation utilities, thus the linuxized ACPICA patches may
+ break the Linux kernel, leaving us build/boot failures. In order to
+ avoid breaking Linux bisection, fixes are applied directly to the
+ linuxized ACPICA patches during the release process. When the release
+ fixups are backported to the upstream ACPICA sources, they must follow
+ the upstream ACPICA rules and so further modifications may appear.
+ That may result in the appearance of new divergences.
+ 5. Fast tracking of ACPICA commits - Some ACPICA commits are regression
+ fixes or stable-candidate material, so they are applied in advance with
+ respect to the ACPICA release process. If such commits are reverted or
+ rebased on the ACPICA side in order to offer better solutions, new ACPICA
+ divergences are generated.
+
+ACPICA Development
+==================
+
+This paragraph guides Linux developers to use the ACPICA upstream release
+utilities to obtain Linux patches corresponding to upstream ACPICA commits
+before they become available from the ACPICA release process.
+
+ 1. Cherry-pick an ACPICA commit
+
+ First you need to git clone the ACPICA repository and the ACPICA change
+ you want to cherry pick must be committed into the local repository.
+
+ Then the gen-patch.sh command can help to cherry-pick an ACPICA commit
+ from the ACPICA local repository::
+
+ $ git clone https://github.com/acpica/acpica
+ $ cd acpica
+ $ generate/linux/gen-patch.sh -u [commit ID]
+
+ Here the commit ID is the ACPICA local repository commit ID you want to
+ cherry pick. It can be omitted if the commit is "HEAD".
+
+ 2. Cherry-pick recent ACPICA commits
+
+ Sometimes you need to rebase your code on top of the most recent ACPICA
+ changes that haven't been applied to Linux yet.
+
+ You can generate the ACPICA release series yourself and rebase your code on
+ top of the generated ACPICA release patches::
+
+ $ git clone https://github.com/acpica/acpica
+ $ cd acpica
+ $ generate/linux/make-patches.sh -u [commit ID]
+
+ The commit ID should be the last ACPICA commit accepted by Linux. Usually,
+ it is the commit modifying ACPI_CA_VERSION. It can be found by executing
+ "git blame source/include/acpixf.h" and referencing the line that contains
+ "ACPI_CA_VERSION".
+
+ 3. Inspect the current divergences
+
+ If you have local copies of both Linux and upstream ACPICA, you can generate
+ a diff file indicating the state of the current divergences::
+
+ # git clone https://github.com/acpica/acpica
+ # git clone https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
+ # cd acpica
+ # generate/linux/divergences.sh -s ../linux
diff --git a/Documentation/driver-api/acpi/scan_handlers.rst b/Documentation/driver-api/acpi/scan_handlers.rst
new file mode 100644
index 000000000..7a197b3a3
--- /dev/null
+++ b/Documentation/driver-api/acpi/scan_handlers.rst
@@ -0,0 +1,83 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+==================
+ACPI Scan Handlers
+==================
+
+:Copyright: |copy| 2012, Intel Corporation
+
+:Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+
+During system initialization and ACPI-based device hot-add, the ACPI namespace
+is scanned in search of device objects that generally represent various pieces
+of hardware. This causes a struct acpi_device object to be created and
+registered with the driver core for every device object in the ACPI namespace
+and the hierarchy of those struct acpi_device objects reflects the namespace
+layout (i.e. parent device objects in the namespace are represented by parent
+struct acpi_device objects and analogously for their children). Those struct
+acpi_device objects are referred to as "device nodes" in what follows, but they
+should not be confused with struct device_node objects used by the Device Trees
+parsing code (although their role is analogous to the role of those objects).
+
+During ACPI-based device hot-remove device nodes representing pieces of hardware
+being removed are unregistered and deleted.
+
+The core ACPI namespace scanning code in drivers/acpi/scan.c carries out basic
+initialization of device nodes, such as retrieving common configuration
+information from the device objects represented by them and populating them with
+appropriate data, but some of them require additional handling after they have
+been registered. For example, if the given device node represents a PCI host
+bridge, its registration should cause the PCI bus under that bridge to be
+enumerated and PCI devices on that bus to be registered with the driver core.
+Similarly, if the device node represents a PCI interrupt link, it is necessary
+to configure that link so that the kernel can use it.
+
+Those additional configuration tasks usually depend on the type of the hardware
+component represented by the given device node which can be determined on the
+basis of the device node's hardware ID (HID). They are performed by objects
+called ACPI scan handlers represented by the following structure::
+
+ struct acpi_scan_handler {
+ const struct acpi_device_id *ids;
+ struct list_head list_node;
+ int (*attach)(struct acpi_device *dev, const struct acpi_device_id *id);
+ void (*detach)(struct acpi_device *dev);
+ };
+
+where ids is the list of IDs of device nodes the given handler is supposed to
+take care of, list_node is the hook to the global list of ACPI scan handlers
+maintained by the ACPI core and the .attach() and .detach() callbacks are
+executed, respectively, after registration of new device nodes and before
+unregistration of device nodes the handler attached to previously.
+
+The namespace scanning function, acpi_bus_scan(), first registers all of the
+device nodes in the given namespace scope with the driver core. Then, it tries
+to match a scan handler against each of them using the ids arrays of the
+available scan handlers. If a matching scan handler is found, its .attach()
+callback is executed for the given device node. If that callback returns 1,
+that means that the handler has claimed the device node and is now responsible
+for carrying out any additional configuration tasks related to it. It also will
+be responsible for preparing the device node for unregistration in that case.
+The device node's handler field is then populated with the address of the scan
+handler that has claimed it.
+
+If the .attach() callback returns 0, it means that the device node is not
+interesting to the given scan handler and may be matched against the next scan
+handler in the list. If it returns a (negative) error code, that means that
+the namespace scan should be terminated due to a serious error. The error code
+returned should then reflect the type of the error.
+
+The namespace trimming function, acpi_bus_trim(), first executes .detach()
+callbacks from the scan handlers of all device nodes in the given namespace
+scope (if they have scan handlers). Next, it unregisters all of the device
+nodes in that scope.
+
+ACPI scan handlers can be added to the list maintained by the ACPI core with the
+help of the acpi_scan_add_handler() function taking a pointer to the new scan
+handler as an argument. The order in which scan handlers are added to the list
+is the order in which they are matched against device nodes during namespace
+scans.
+
+All scan handles must be added to the list before acpi_bus_scan() is run for the
+first time and they cannot be removed from it.
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-29 16:04:19 +0000