asgardius/android_kernel_motorola_sm6225
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

stm class: Document the stm_source interface

Browse source 
This patch adds a description of the stm_source device class, an
interface for the kernel code to send traces over STM devices.

Cc: linux-api@vger.kernel.org
Cc: Chunyan Zhang <zhang.chunyan@linaro.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
This commit is contained in:
Alexander Shishkin 2016-07-14 13:39:20 +03:00
parent a0ebf519b8
commit bd56618972
1 changed files with 25 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

29
Documentation/trace/stm.txt
View file

@ -69,12 +69,33 @@ stm device's channel mmio region is 64 bytes and hardware page size is
width==64, you should be able to mmap() one page on this file width==64, you should be able to mmap() one page on this file
descriptor and obtain direct access to an mmio region for 64 channels. descriptor and obtain direct access to an mmio region for 64 channels.
For kernel-based trace sources, there is "stm_source" device
class. Devices of this class can be connected and disconnected to/from
stm devices at runtime via a sysfs attribute.
Examples of STM devices are Intel(R) Trace Hub [1] and Coresight STM Examples of STM devices are Intel(R) Trace Hub [1] and Coresight STM
[2]. [2].
stm_source
==========
For kernel-based trace sources, there is "stm_source" device
class. Devices of this class can be connected and disconnected to/from
stm devices at runtime via a sysfs attribute called "stm_source_link"
by writing the name of the desired stm device there, for example:
$ echo dummy_stm.0 > /sys/class/stm_source/console/stm_source_link
For examples on how to use stm_source interface in the kernel, refer
to stm_console or stm_heartbeat drivers.
stm_console
===========
One implementation of this interface also used in the example above is
the "stm_console" driver, which basically provides a one-way console
for kernel messages over an stm device.
To configure the master/channel pair that will be assigned to this
console in the STP stream, create a "console" policy entry (see the
beginning of this text on how to do that). When initialized, it will
consume one channel.
[1] https://software.intel.com/sites/default/files/managed/d3/3c/intel-th-developer-manual.pdf [1] https://software.intel.com/sites/default/files/managed/d3/3c/intel-th-developer-manual.pdf
[2] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0444b/index.html [2] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0444b/index.html