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