Documentation/trace/intel_th.rst

1 .. SPDX-License-Identifier: GPL-2.0
8 --------
12 sources over several types of trace output ports encoded in System
13 Trace Protocol (MIPI STPv2) and is intended to perform full system
18 switch (Global Trace Hub, GTH). These devices are placed on a bus of
23   - Software Trace Hub (STH), trace source, which is a System Trace
25   - Memory Storage Unit (MSU), trace output, which allows storing
26     trace hub output in system memory,
27   - Parallel Trace Interface output (PTI), trace output to an external
29   - Global Trace Hub (GTH), which is a switch and a central component
33 Documentation/ABI/testing/sysfs-bus-intel_th-output-devices, the most
39 description is at Documentation/ABI/testing/sysfs-bus-intel_th-devices-gth.
45 MSU can be configured to collect trace data into a system memory
54 [1] https://software.intel.com/sites/default/files/managed/d3/3c/intel-th-developer-manual.pdf
56 Bus and Subdevices
57 ------------------
59 For each Intel TH device in the system a bus of its own is
61 devices were enumerated. All TH subdevices (devices on intel_th bus)
62 begin with this id: 0-gth, 0-msc0, 0-msc1, 0-pti, 0-sth, which is
70 -------------
74 	$ cat /sys/bus/intel_th/devices/0-msc0/port
79 	$ echo 0 > /sys/bus/intel_th/devices/0-gth/masters/33
81 # allocate a 2-windowed multiblock buffer on the first memory
84 	$ echo multi > /sys/bus/intel_th/devices/0-msc0/mode
85 	$ echo 64,64 > /sys/bus/intel_th/devices/0-msc0/nr_pages
89 	$ echo 1 > /sys/bus/intel_th/devices/0-msc0/wrap
93 	$ echo 1 > /sys/bus/intel_th/devices/0-msc0/active
99 	$ echo 0 > /sys/bus/intel_th/devices/0-msc0/active
106 ------------------
123 will show up on the intel_th bus. Also, trace configuration and
128 --------------
130 The Memory Storage Unit (MSU) driver provides an in-kernel API for
136  - notifying the software sink that a particular window is full, and
141  - tracking the "locked" state of windows and providing a way for the
145 An example sink driver, msu-sink illustrates the implementation of a
150 file (assuming msu-sink.ko is loaded).