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Configuration

The I3C Core is configured with a single node of the YAML configuration file (e.g. AHB or AXI in i3c_core_config).

Legal parameters are defined in the i3c_core_config schema.

Example I3C core configuration node will look similarly to:

axi:
  CmdFifoDepth: 64
  RxFifoDepth: 64
  TxFifoDepth: 64
  RespFifoDepth: 64
  IbiFifoDepth: 64
  IbiFifoExtSize: False
  DatDepth: 32
  DctDepth: 32
  FrontendBusInterface: "AXI"
  FrontendBusAddrWidth: 32
  FrontendBusDataWidth: 64

Usage

To generate the I3C configuration, run:

make generate CFG_NAME=<name> CFG_FILE=<path/to/.yaml>

Where the

  • CFG_NAME is a name of the target yaml configuration (axi in an example above) - if not specified it's set to default.
  • CFG_FILE contains a collection of supported configurations - by default it's i3c_core_configs.yaml

Extending the configuration

Schema

In order to add a configuration parameter it first needs to be defined in the schema.

Each node is specified by:

  • description that explains the parameter usage / purpose
  • type which should be one of: integer, string, boolean, number or in more complex cases (that require some additional handling in the config generation): object, array
  • type-dependent validation:
    • For number / integer this could be minimum, maximum, exclusiveMinimum, exclusiveMaximum
    • For strings it could be e.g. pattern
    • anyOf, allOf, oneOf that allows to specify a subset of valid values for the parameter to be validated against, similarly not to specify illegal value subset
  • default that defines a default value for the parameter in case it's not explicitly set in the configuration

A property name can be appended to the required field in the schema to enforce the property to be specified in each configuration node.

When in doubt please refer to the JSON Schema Specification.

I3C configuration tool

If a parameter is of a basic type such as integer, string, boolean, number it ought to be handled by the i3c_core_config.py tool automatically.

The I3CCoreConfig class is based on the I3C Schema and specified configuration. The parameter validation is performed using the jsonschema tool.

In order to handle more complex parameter types (object, array) or to perform a parameter transformation the output function of CmdLineOpts needs to be modified to produce the command line options properly and the I3CCoreConfig for the proper defines.svh generation.

See I3CCoreConfig class for parameter transformation (e.g. FrontendBusInterface -> I3C_USE_AHB / I3C_USE_AXI) and the parameter case change (PascalCase -> UPPER_SNAKE_CASE) reference.

Tests

The configuration tests utilize pytest and fixtures. All configurations in test_configs.yaml will be executed. The test cases are divided into:

  • invalid - illegal configurations with name prefixed with invalid_
  • edge - configuration legal edge cases prefixed with edge_ - checking the maximal / minimal allowed values
  • valid - all other configurations contained within the test_configs file
  • happy_path - utilizing the default configuration from the i3c_core_configs.yaml

In order to extend the test cases add a properly prefixed configuration node to the test_configs.yaml or extend the test cases in test_configs.py.