[PATCH v5 18/19] Documentation: trace: Add documentation for TRBE
From: Suzuki K Poulose <suzuki.poulose@arm.com>
Date: 2021-03-23 12:09:05
Also in:
linux-doc, lkml
Subsystem:
arm/coresight framework and drivers, documentation, the rest, tracing · Maintainers:
Suzuki K Poulose, Jonathan Corbet, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
From: Anshuman Khandual <redacted> Add documentation for the TRBE under trace/coresight. Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-doc@vger.kernel.org Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Anshuman Khandual <redacted> [ Split from the TRBE driver patch ] Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> --- .../trace/coresight/coresight-trbe.rst | 38 +++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 Documentation/trace/coresight/coresight-trbe.rst
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 <anshuman.khandual@arm.com> + :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<N>`` 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
--
2.24.1
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