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Erik Kaneda cefc7ca462 ACPI: PRM: implement OperationRegion handler for the PlatformRtMechanism subtype
Platform Runtime Mechanism (PRM) is a firmware interface that exposes
a set of binary executables that can either be called from the AML
interpreter or device drivers by bypassing the AML interpreter.
This change implements the AML interpreter path.

According to the specification [1], PRM services are listed in an
ACPI table called the PRMT. This patch parses module and handler
information listed in the PRMT and registers the PlatformRtMechanism
OpRegion handler before ACPI tables are loaded.

Each service is defined by a 16-byte GUID and called from writing a
26-byte ASL buffer containing the identifier to a FieldUnit object
defined inside a PlatformRtMechanism OperationRegion.

    OperationRegion (PRMR, PlatformRtMechanism, 0, 26)
    Field (PRMR, BufferAcc, NoLock, Preserve)
    {
        PRMF, 208 // Write to this field to invoke the OperationRegion Handler
    }

The 26-byte ASL buffer is defined as the following:

Byte Offset   Byte Length    Description
=============================================================
     0             1         PRM OperationRegion handler status
     1             8         PRM service status
     9             1         PRM command
    10            16         PRM handler GUID

The ASL caller fills out a 26-byte buffer containing the PRM command
and the PRM handler GUID like so:

    /* Local0 is the PRM data buffer */
    Local0 = buffer (26){}

    /* Create byte fields over the buffer */
    CreateByteField (Local0, 0x9, CMD)
    CreateField (Local0, 0x50, 0x80, GUID)

    /* Fill in the command and data fields of the data buffer */
    CMD = 0 // run command
    GUID = ToUUID("xxxx-xx-xxx-xxxx")

    /*
     * Invoke PRM service with an ID that matches GUID and save the
     * result.
     */
    Local0 = (\_SB.PRMT.PRMF = Local0)

Byte offset 0 - 8 are written by the handler as a status passed back to AML
and used by ASL like so:

    /* Create byte fields over the buffer */
    CreateByteField (Local0, 0x0, PSTA)
    CreateQWordField (Local0, 0x1, USTA)

In this ASL code, PSTA contains a status from the OperationRegion and
USTA contains a status from the PRM service.

The 26-byte buffer is recieved by acpi_platformrt_space_handler. This
handler will look at the command value and the handler guid and take
the approperiate actions.

Command value    Action
=====================================================================
    0            Run the PRM service indicated by the PRM handler
                 GUID (bytes 10-26)

    1            Prevent PRM runtime updates from happening to the
                 service's parent module

    2            Allow PRM updates from happening to the service's parent module

This patch enables command value 0.

Link: https://uefi.org/sites/default/files/resources/Platform%20Runtime%20Mechanism%20-%20with%20legal%20notice.pdf # [1]
Signed-off-by: Erik Kaneda <erik.kaneda@intel.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2021-06-10 15:06:54 +02:00
arch ARM: SoC fixes for 5.13 2021-06-06 13:00:36 -07:00
block block-5.13-2021-05-22 2021-05-22 07:40:34 -10:00
certs Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
crypto for-5.13/drivers-2021-04-27 2021-04-28 14:39:37 -07:00
Documentation Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2021-05-29 18:24:00 -10:00
drivers ACPI: PRM: implement OperationRegion handler for the PlatformRtMechanism subtype 2021-06-10 15:06:54 +02:00
fs Miscellaneous ext4 bug fixes for v5.13 2021-06-06 14:24:13 -07:00
include ACPI: PRM: implement OperationRegion handler for the PlatformRtMechanism subtype 2021-06-10 15:06:54 +02:00
init pid: take a reference when initializing cad_pid 2021-06-05 08:58:11 -07:00
ipc ipc/mqueue, msg, sem: avoid relying on a stack reference past its expiry 2021-05-22 15:09:07 -10:00
kernel Networking fixes for 5.13-rc5, including fixes from bpf, wireless, 2021-06-04 18:25:39 -07:00
lib lib: crc64: fix kernel-doc warning 2021-06-05 08:58:12 -07:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm mm, hugetlb: fix simple resv_huge_pages underflow on UFFDIO_COPY 2021-06-05 08:58:12 -07:00
net Networking fixes for 5.13-rc5, including fixes from bpf, wireless, 2021-06-04 18:25:39 -07:00
samples VFIO fixes for v5.13-rc5 2021-06-03 11:52:24 -07:00
scripts kbuild: Quote OBJCOPY var to avoid a pahole call break the build 2021-05-27 11:32:56 -07:00
security trusted-keys: match tpm_get_ops on all return paths 2021-05-12 22:36:37 +03:00
sound sound fixes for 5.13-rc5 2021-06-04 10:13:20 -07:00
tools Merge branch 'akpm' (patches from Andrew) 2021-06-05 10:55:41 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: VMX: update vcpu posted-interrupt descriptor when assigning device 2021-05-27 07:58:23 -04:00
.clang-format cxl for 5.12 2021-02-24 09:38:36 -08:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: use private address for Michel Lespinasse 2021-06-05 08:58:12 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking fixes for 5.13-rc5, including fixes from bpf, wireless, 2021-06-04 18:25:39 -07:00
Makefile Linux 5.13-rc5 2021-06-06 15:47:27 -07:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
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    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.