From 0580565dd717cb135633ebdbc1d84fe6b0a3fa78 Mon Sep 17 00:00:00 2001 From: Iwona Winiarska Date: Tue, 8 Feb 2022 16:36:39 +0100 Subject: [PATCH] docs: Add PECI documentation 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 Acked-by: Joel Stanley Signed-off-by: Iwona Winiarska Link: https://lore.kernel.org/r/20220208153639.255278-14-iwona.winiarska@intel.com Signed-off-by: Greg Kroah-Hartman --- Documentation/index.rst | 1 + Documentation/peci/index.rst | 16 +++++++++++ Documentation/peci/peci.rst | 51 ++++++++++++++++++++++++++++++++++++ MAINTAINERS | 1 + 4 files changed, 69 insertions(+) create mode 100644 Documentation/peci/index.rst create mode 100644 Documentation/peci/peci.rst diff --git a/Documentation/index.rst b/Documentation/index.rst index b58692d687f6..1988c19d9daf 100644 --- a/Documentation/index.rst +++ b/Documentation/index.rst @@ -138,6 +138,7 @@ needed). scheduler/index mhi/index tty/index + peci/index Architecture-agnostic documentation ----------------------------------- diff --git a/Documentation/peci/index.rst b/Documentation/peci/index.rst new file mode 100644 index 000000000000..989de10416e7 --- /dev/null +++ b/Documentation/peci/index.rst @@ -0,0 +1,16 @@ +.. SPDX-License-Identifier: GPL-2.0-only + +==================== +Linux PECI Subsystem +==================== + +.. toctree:: + + peci + +.. only:: subproject and html + + Indices + ======= + + * :ref:`genindex` diff --git a/Documentation/peci/peci.rst b/Documentation/peci/peci.rst new file mode 100644 index 000000000000..331b1ec00e22 --- /dev/null +++ b/Documentation/peci/peci.rst @@ -0,0 +1,51 @@ +.. 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 diff --git a/MAINTAINERS b/MAINTAINERS index b7992853a427..23fba6b2609f 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -15117,6 +15117,7 @@ M: Iwona Winiarska L: openbmc@lists.ozlabs.org (moderated for non-subscribers) S: Supported F: Documentation/devicetree/bindings/peci/ +F: Documentation/peci/ F: drivers/peci/ F: include/linux/peci-cpu.h F: include/linux/peci.h