1.. SPDX-License-Identifier: GPL-2.0-only 2 3======== 4Overview 5======== 6 7The Platform Environment Control Interface (PECI) is a communication 8interface between Intel processor and management controllers 9(e.g. Baseboard Management Controller, BMC). 10PECI provides services that allow the management controller to 11configure, monitor and debug platform by accessing various registers. 12It defines a dedicated command protocol, where the management 13controller is acting as a PECI originator and the processor - as 14a PECI responder. 15PECI can be used in both single processor and multiple-processor based 16systems. 17 18NOTE: 19Intel PECI specification is not released as a dedicated document, 20instead it is a part of External Design Specification (EDS) for given 21Intel CPU. External Design Specifications are usually not publicly 22available. 23 24PECI Wire 25--------- 26 27PECI Wire interface uses a single wire for self-clocking and data 28transfer. It does not require any additional control lines - the 29physical layer is a self-clocked one-wire bus signal that begins each 30bit with a driven, rising edge from an idle near zero volts. The 31duration of the signal driven high allows to determine whether the bit 32value is logic '0' or logic '1'. PECI Wire also includes variable data 33rate established with every message. 34 35For PECI Wire, each processor package will utilize unique, fixed 36addresses within a defined range and that address should 37have a fixed relationship with the processor socket ID - if one of the 38processors is removed, it does not affect addresses of remaining 39processors. 40 41PECI subsystem internals 42------------------------ 43 44.. kernel-doc:: include/linux/peci.h 45.. kernel-doc:: drivers/peci/internal.h 46.. kernel-doc:: drivers/peci/core.c 47.. kernel-doc:: drivers/peci/request.c 48 49PECI CPU Driver API 50------------------- 51.. kernel-doc:: drivers/peci/cpu.c 52