From 4af432186122bb274b76e7ac549073122c41d2fb Mon Sep 17 00:00:00 2001 From: Anshuman Khandual Date: Mon, 5 Apr 2021 17:43:06 +0100 Subject: Documentation: trace: Add documentation for TRBE Add documentation for the TRBE under trace/coresight. Cc: Jonathan Corbet Cc: linux-doc@vger.kernel.org Signed-off-by: Anshuman Khandual [ Split from the TRBE driver patch ] Signed-off-by: Suzuki K Poulose Link: https://lore.kernel.org/r/20210405164307.1720226-20-suzuki.poulose@arm.com Signed-off-by: Mathieu Poirier --- Documentation/trace/coresight/coresight-trbe.rst | 38 ++++++++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 Documentation/trace/coresight/coresight-trbe.rst (limited to 'Documentation/trace') diff --git a/Documentation/trace/coresight/coresight-trbe.rst b/Documentation/trace/coresight/coresight-trbe.rst new file mode 100644 index 000000000000..b9928ef148da --- /dev/null +++ b/Documentation/trace/coresight/coresight-trbe.rst @@ -0,0 +1,38 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================== +Trace Buffer Extension (TRBE). +============================== + + :Author: Anshuman Khandual + :Date: November 2020 + +Hardware Description +-------------------- + +Trace Buffer Extension (TRBE) is a percpu hardware which captures in system +memory, CPU traces generated from a corresponding percpu tracing unit. This +gets plugged in as a coresight sink device because the corresponding trace +generators (ETE), are plugged in as source device. + +The TRBE is not compliant to CoreSight architecture specifications, but is +driven via the CoreSight driver framework to support the ETE (which is +CoreSight compliant) integration. + +Sysfs files and directories +--------------------------- + +The TRBE devices appear on the existing coresight bus alongside the other +coresight devices:: + + >$ ls /sys/bus/coresight/devices + trbe0 trbe1 trbe2 trbe3 + +The ``trbe`` named TRBEs are associated with a CPU.:: + + >$ ls /sys/bus/coresight/devices/trbe0/ + align flag + +*Key file items are:-* + * ``align``: TRBE write pointer alignment + * ``flag``: TRBE updates memory with access and dirty flags -- cgit v1.2.3