On Thu, Apr 14, 2022 at 07:44:57AM +0100, Mike Leach wrote:
Add documentation covering the configfs updates that allow binary configuration files to be loaded and unloaded via configfs, along with the demonstration programs in samples.
Signed-off-by: Mike Leach mike.leach@linaro.org
.../trace/coresight/coresight-config.rst | 166 +++++++++++++++++- 1 file changed, 160 insertions(+), 6 deletions(-)
diff --git a/Documentation/trace/coresight/coresight-config.rst b/Documentation/trace/coresight/coresight-config.rst index 6d5ffa6f7347..9354cfcc04e3 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
"last_load_status" has been removed.
$ cd autofdo/ $ ls description feature_refs preset1 preset3 preset5 preset7 preset9@@ -278,9 +278,16 @@ 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 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. @@ -289,6 +296,153 @@ 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.
+An example of a custom configuration module is found in './samples/coresight'.
+Using a Binary Configuration File +---------------------------------
+The './tools/coresight' directory contains example programs to generate and +read and print binary configuration files.
+Building the tools creates the 'coresight-cfg-file-gen' 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-example1.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. Alternatively, addition examples can be added to the +'coresight-cfg-file-gen' program::
- $ ./coresight-cfg-file-gen
- Coresight Configuration file Generator
- Generating example1 example
+The program 'coresight-cfg-file-read' can read back and print a configuration +binary. This is built using the file reader from the driver code +(coresight-config-file.c), which is copied over into './tools/coresight' at +build time.::
- ./coresight-cfg-file-read example1.cscfg
- CoreSight Configuration file reader
- Configuration name : autofdo3
- Uses 1 features:-
- Feature-1: strobing
- Provides 4 sets of preset values, 2 presets per set
- set[0]: 0x7d0, 0x64,
- set[1]: 0x7d0, 0x3e8,
- set[2]: 0x7d0, 0x1388,
- set[3]: 0x7d0, 0x2710,
- File contains no features
+There are additional attributes in the configurations directory - load and +unload 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 load unload
- $ cat example1.cscfg > /config/cs-syscfg/configurations/load
- $ ls /config/cs-syscfg/configurations/
- autofdo autofdo3 last_load_status load unload
Same
More comments tomorrow.
Thanks, Mathieu
+To unload, use the same file in the unload attribute::
- $ cat example1.cscfg > /config/cs-syscfg/configurations/unload
- ls /config/cs-syscfg/configurations/
- autofdo load unload
+Binary Configuration File Format +--------------------------------
+The file format is defined in the source file **coresight-config-file.h**
+The source reader and generator examples produce a binary of this format.
+This arrangement is reproduced below:-
+Overall File structure +~~~~~~~~~~~~~~~~~~~~~~
+::
- [cscfg_file_header] // Mandatory
- [CONFIG_ELEM] // Optional - one per file, if present, first element in file.
- [FEATURE_ELEM]* // Optional - multiple, defined by cscfg_file_header.nr_features
+File is invalid if both [CONFIG_ELEM] and [FEATURE_ELEM] are omitted.
+A file that contains only [FEATURE_ELEM] may be loaded, and the features used +by subsequently loaded files with [CONFIG_ELEM] elements.
+Where [CONFIG_ELEM] is present, then **cscfg_file_header.nr_features** and +**CONFIG_ELEM.nr_feat_refs** must have the same value.
+CONFIG_ELEM element +~~~~~~~~~~~~~~~~~~~
+::
- [cscfg_file_elem_header] // header length value to end of feature strings.
- [cscfg_file_elem_str] // name of the configuration.
- [cscfg_file_elem_str] // description of configuration.
- [u16 value](nr_presets) // number of defined presets.
- [u32 value](nr_total_params) // total parameters defined by all used features.
- [u16 value](nr_feat_refs) // number of features referenced by the configuration
- [u64 values] * (nr_presets * nr_total_params) // the preset values.
- [cscfg_file_elem_str] * (nr_feat_refs) // the features used in the configurations.
+FEATURE_ELEM element +~~~~~~~~~~~~~~~~~~~~
+::
- [cscfg_file_elem_header] // header length is total bytes to end of param structures.
- [cscfg_file_elem_str] // feature name.
- [cscfg_file_elem_str] // feature description.
- [u32 value](match_flags) // flags to associate the feature with a device.
- [u16 value](nr_regs) // number of registers.
- [u16 value](nr_params) // number of parameters.
- [cscfg_regval_desc struct] * (nr_regs) // register definitions
- [PARAM_ELEM] * (nr_params) // parameters definitions
+PARAM_ELEM element +~~~~~~~~~~~~~~~~~~
+::
- [cscfg_file_elem_str] // parameter name.
- [u64 value](param_value] // initial value.
+Additional definitions. +~~~~~~~~~~~~~~~~~~~~~~~
+The following structures are defined in **coresight-config-file.h**
- **struct cscfg_file_header** : This structure contains an initial magic number, the total
- length of the file, and the number of features in the file.
- **struct cscfg_file_elem_header**: This defines the total length and type of a CONFIG_ELEM
- or a FEATURE_ELEM.
- **struct cscfg_file_elem_str**: This defines a string and its length.
+The magic number in cscfg_file_header is defined as two bitfields::
- [31:8] Fixed magic number to identify file type.
- [7:0] Current file format version.
+The following defines determine the maximum overall file size and maximum individual +string size::
- CSCFG_FILE_MAXSIZE // maximum overall file size.
- CSCFG_FILE_STR_MAXSIZE // maximum individual string size.
-- 2.17.1