ralgen: A FuseSoC generator for UVM RAL package
ralgen.py script is implemented as a
which enables the automatic creation of the SystemVerilog UVM RAL package and
its insertion into the dependency tree when compiling the DV testbench.
This approach is useful for DV simulation flows that use FuseSoC as the backend to generate the filelist for compilation. A separate RAL package generation step is no longer needed since it gets handled within FuseSoC.
ralgen.core file registers the
ralgen generator. The FuseSoC
core file that ‘calls’ the generator adds it as a dependency. When calling the
generator, the following parameters are set:
- name (mandatory): Name of the RAL package (typically, same is the IP).
- dv_base_prefix (optional): The prefix added to the base classes from
which the register classes are derived. Set this option to derive the register
classes not from the default
dv_base_reg, but from user defined custom class definitions.
- ip_hjson: Path to the hjson specification written for an IP which includes
the register descriptions. This needs to be a valid input for
- top_hjson: Path to the hjson specification for a top level design. This
needs to be a valid input for
Only one of the last two arguments is mandatory. If both are set, or if neither of them are, then the tool throws an error and exits.
The following snippet shows how it is called:
generate: ral: generator: ralgen parameters: name: <name> ip_hjson|top_hjson: <path-to-hjson-spec> [dv_base_prefix: my_base] targets: default: ... generate: - ral
Note that the path to
hjson specification in the snippet above is relative
to the core file in which the generator is called.
When FuseSoC processes the dependency list and encounters a generator, it
passes a YAML file containing the above parameters to the generator tool
ralgen.py) as a single input. It then parses the YAML input to
extract those parameters.
ralgen.py really is just a wrapper around
reggen and the
scripts, which are the ones that actually create the RAL package.
Due to the way those scripts are implemented, RAL packages for the IP level
testbenches are generated using
reggen, and for the chip level
util/topgen.py. Which one to choose is decided by whether
top_hjson parameter is supplied.
In addition, the
ralgen.py script also creates a FuseSoC core file. It uses
name parameter to derive the
name for the generated core file.
The generated core file adds
lowrisc:dv:dv_base_reg as a dependency for
the generated RAL package. This is required because our DV register block,
register and field models are derived from the
DV library of classes. This
ensures the right compilation order is maintained. If the
argument is set, then it adds
lowrisc:dv:my_base_reg as an extra
my_base is the value of the argument as shown in the
example above. This core file and the associated sources are assumed to be
available in the provided FuseSoC search paths.
The script is not designed to be manually invoked, but in theory, it can be, if a YAML file that contains the right set of parameters is presented to it (compliant with FuseSoC).
If the user wishes to create the RAL package manually outside of the DV
simulation flow, then the
make command can be invoked in the
instead. It generates the RTL, DV and SW collaterals for all IPs, as well as
the top level in a single step.