| .. 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 |
