52 lines
1.8 KiB
ReStructuredText
52 lines
1.8 KiB
ReStructuredText
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.. SPDX-License-Identifier: GPL-2.0-only
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========
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Overview
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========
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The Platform Environment Control Interface (PECI) is a communication
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interface between Intel processor and management controllers
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(e.g. Baseboard Management Controller, BMC).
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PECI provides services that allow the management controller to
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configure, monitor and debug platform by accessing various registers.
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It defines a dedicated command protocol, where the management
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controller is acting as a PECI originator and the processor - as
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a PECI responder.
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PECI can be used in both single processor and multiple-processor based
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systems.
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NOTE:
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Intel PECI specification is not released as a dedicated document,
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instead it is a part of External Design Specification (EDS) for given
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Intel CPU. External Design Specifications are usually not publicly
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available.
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PECI Wire
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---------
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PECI Wire interface uses a single wire for self-clocking and data
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transfer. It does not require any additional control lines - the
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physical layer is a self-clocked one-wire bus signal that begins each
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bit with a driven, rising edge from an idle near zero volts. The
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duration of the signal driven high allows to determine whether the bit
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value is logic '0' or logic '1'. PECI Wire also includes variable data
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rate established with every message.
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For PECI Wire, each processor package will utilize unique, fixed
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addresses within a defined range and that address should
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have a fixed relationship with the processor socket ID - if one of the
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processors is removed, it does not affect addresses of remaining
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processors.
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PECI subsystem internals
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------------------------
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.. kernel-doc:: include/linux/peci.h
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.. kernel-doc:: drivers/peci/internal.h
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.. kernel-doc:: drivers/peci/core.c
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.. kernel-doc:: drivers/peci/request.c
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PECI CPU Driver API
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-------------------
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.. kernel-doc:: drivers/peci/cpu.c
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