mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
synced 2024-12-28 16:52:18 +00:00
0580565dd7
Add a brief overview of PECI and PECI wire interface. The documentation also contains kernel-doc for PECI subsystem internals and PECI CPU Driver API. Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> Acked-by: Joel Stanley <joel@jms.id.au> Signed-off-by: Iwona Winiarska <iwona.winiarska@intel.com> Link: https://lore.kernel.org/r/20220208153639.255278-14-iwona.winiarska@intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
52 lines
1.8 KiB
ReStructuredText
52 lines
1.8 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0-only
|
|
|
|
========
|
|
Overview
|
|
========
|
|
|
|
The Platform Environment Control Interface (PECI) is a communication
|
|
interface between Intel processor and management controllers
|
|
(e.g. Baseboard Management Controller, BMC).
|
|
PECI provides services that allow the management controller to
|
|
configure, monitor and debug platform by accessing various registers.
|
|
It defines a dedicated command protocol, where the management
|
|
controller is acting as a PECI originator and the processor - as
|
|
a PECI responder.
|
|
PECI can be used in both single processor and multiple-processor based
|
|
systems.
|
|
|
|
NOTE:
|
|
Intel PECI specification is not released as a dedicated document,
|
|
instead it is a part of External Design Specification (EDS) for given
|
|
Intel CPU. External Design Specifications are usually not publicly
|
|
available.
|
|
|
|
PECI Wire
|
|
---------
|
|
|
|
PECI Wire interface uses a single wire for self-clocking and data
|
|
transfer. It does not require any additional control lines - the
|
|
physical layer is a self-clocked one-wire bus signal that begins each
|
|
bit with a driven, rising edge from an idle near zero volts. The
|
|
duration of the signal driven high allows to determine whether the bit
|
|
value is logic '0' or logic '1'. PECI Wire also includes variable data
|
|
rate established with every message.
|
|
|
|
For PECI Wire, each processor package will utilize unique, fixed
|
|
addresses within a defined range and that address should
|
|
have a fixed relationship with the processor socket ID - if one of the
|
|
processors is removed, it does not affect addresses of remaining
|
|
processors.
|
|
|
|
PECI subsystem internals
|
|
------------------------
|
|
|
|
.. kernel-doc:: include/linux/peci.h
|
|
.. kernel-doc:: drivers/peci/internal.h
|
|
.. kernel-doc:: drivers/peci/core.c
|
|
.. kernel-doc:: drivers/peci/request.c
|
|
|
|
PECI CPU Driver API
|
|
-------------------
|
|
.. kernel-doc:: drivers/peci/cpu.c
|