[PATCH 6/6] Documentation: coresight: Update coresight configuration docs

[Mike Leach]

Add documentation covering the configfs updates that allow
binary configuration files to be loaded and unloaded, along
with the demonstration programs in samples.

Signed-off-by: Mike Leach <mike.leach at linaro.org>
---
 .../trace/coresight/coresight-config.rst      | 65 +++++++++++++++++--
 1 file changed, 59 insertions(+), 6 deletions(-)

diff --git a/Documentation/trace/coresight/coresight-config.rst b/Documentation/trace/coresight/coresight-config.rst
index 911db4da7f99..8ea640b3f6f9 100644
--- a/Documentation/trace/coresight/coresight-config.rst
+++ b/Documentation/trace/coresight/coresight-config.rst
@@ -152,7 +152,7 @@ follows::
 
     $ cd configurations/
     $ ls
-    autofdo
+    autofdo last_load_status  load  unload
     $ cd autofdo/
     $ ls
     description   preset1  preset3  preset5  preset7  preset9
@@ -247,9 +247,19 @@ Creating and Loading Custom Configurations
 ==========================================
 
 Custom configurations and / or features can be dynamically loaded into the
-system by using a loadable module.
+system by using a loadable module, or by loading a binary configuration
+file in configfs.
+
+Loaded configurations can use previously loaded features. The system will
+ensure that it is not possible to unload a feature that is currently in
+use, by enforcing the unload order as the strict reverse of the load order.
+
+An example of a custom configuration module, and generators for binary
+configuration files are found in './samples/coresight'.
+
 
-An example of a custom configuration is found in ./samples/coresight.
+Using a Loadable Module
+-----------------------
 
 This creates a new configuration that uses the existing built in
 strobing feature, but provides a different set of presets.
@@ -258,6 +268,49 @@ When the module is loaded, then the configuration appears in the configfs
 file system and is selectable in the same way as the built in configuration
 described above.
 
-Configurations can use previously loaded features. The system will ensure
-that it is not possible to unload a feature that is currently in use, by
-enforcing the unload order as the strict reverse of the load order.
+The file 'coresight-cfg-sample.c' contains the configuration and module
+initialisation code needed to create the loadable module.
+
+This will be built alongside the kernel modules if select in KConfig.
+
+
+Using a Binary Configuration File
+---------------------------------
+
+Building the samples creates the 'coresight-cfg-filegen' program that will
+generate a configuration binary 'example1.cscfg' that can be loaded into the
+system using configfs. The configuration declared in the source file
+'coresight-cfg-filegen.c' is named 'autofdo3' - the name that will be used
+once loaded.
+
+The source files 'coresight-cfg-bufw.h' and 'coresight-cfg-bufw.c' provide a
+standard function to convert a configuration declared in 'C' into the correct
+binary buffer format. These files can be re-used to create new custom
+configurations.
+
+The program  'coresight-cfg-file-read' can read back and print a configuration
+binary. This is built using the reader from the driver code.
+
+There are additional attributes in the configurations directory - load, unload
+and last_load_status that can be used to load and unload configuration
+binary files. To load, 'cat' the binary config into the load attribute::
+
+    $ ls /config/cs-syscfg/configurations/
+    autofdo last_load_status  load  unload
+    $ cat example1.cscfg > /config/cs-syscfg/configurations/load
+    $ ls /config/cs-syscfg/configurations/
+    autofdo  autofdo3  last_load_status  load  unload
+    $ cat /config/cs-syscfg/configurations/last_load_status
+    OK: configuration file loaded (autofdo3).
+
+To unload, use the same file in the unload attribute::
+
+    $ cat example1.cscfg > /config/cs-syscfg/configurations/unload
+    $ cat /config/cs-syscfg/configurations/last_load_status
+    OK: configuration file unloaded (autofdo3).
+    ls /config/cs-syscfg/configurations/
+    autofdo  last_load_status  load  unload
+
+The generator and reader programs can also be built directly, separately from
+the kernel build by using the 'Makefile.host' file. This allows binaries to be
+created on the host machine when cross compiling.
-- 
2.17.1