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 $ 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 + +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.