1.. SPDX-License-Identifier: GPL-2.0
2
3==============================
4Trace Buffer Extension (TRBE).
5==============================
6
7    :Author:   Anshuman Khandual <anshuman.khandual@arm.com>
8    :Date:     November 2020
9
10Hardware Description
11--------------------
12
13Trace Buffer Extension (TRBE) is a percpu hardware which captures in system
14memory, CPU traces generated from a corresponding percpu tracing unit. This
15gets plugged in as a coresight sink device because the corresponding trace
16generators (ETE), are plugged in as source device.
17
18The TRBE is not compliant to CoreSight architecture specifications, but is
19driven via the CoreSight driver framework to support the ETE (which is
20CoreSight compliant) integration.
21
22Sysfs files and directories
23---------------------------
24
25The TRBE devices appear on the existing coresight bus alongside the other
26coresight devices::
27
28	>$ ls /sys/bus/coresight/devices
29	trbe0  trbe1  trbe2 trbe3
30
31The ``trbe<N>`` named TRBEs are associated with a CPU.::
32
33	>$ ls /sys/bus/coresight/devices/trbe0/
34        align flag
35
36*Key file items are:-*
37   * ``align``: TRBE write pointer alignment
38   * ``flag``: TRBE updates memory with access and dirty flags
39