caravel/openlane/README.rst

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.. _caravel-with-openlane:

Using OpenLANE to Harden Your Design
====================================

You can utilize the Makefile existing here in this directory to do that.

But, first you need to specify 2 things:

.. code:: bash

    export PDK_ROOT=<The location where the pdk is installed>
    export OPENLANE_ROOT=<the absolute path to the openlane directory cloned or to be cloned>

If you don't have openlane already, then you can get it from
`here <https://github.com/efabless/openlane>`__.

**NOTE:**

      We are developing caravel using the latest openlane release v0.12. This will be continuously updated to the latest openlane tag until we reach a stable version of caravel.

Then, you have two options:

#. Create a macro for your design and harden it, then insert it into
   `user_project_wrapper`.

#. Flatten your design with the `user_project_wrapper` and harden them
   as one.

**NOTE:**

      The OpenLANE documentation should cover everything you might
      need to create your design. You can find that
      `here <https://openlane.readthedocs.io/en/latest/>`__.

Option 1: Inserting your design macro into the wrapper
----------------------------------------------------------

This could be done by creating a directory for your design under the ``<your_user_project_root>/openlane/<my-design>`` and adding a configuration file for it under the same
directory. You can follow the instructions given
`here <https://openlane.readthedocs.io/en/latest/#adding-a-design>`__ to
generate an initial configuration file for your design, or you can start
with the following:

.. code:: tcl

    set script_dir [file dirname [file normalize [info script]]]

    set ::env(DESIGN_NAME) <Your Design Name>

    set ::env(DESIGN_IS_CORE) 0
    set ::env(FP_PDN_CORE_RING) 0
    set ::env(GLB_RT_MAXLAYER) 5

    set ::env(VERILOG_FILES) "$script_dir/../../verilog/rtl/<Your RTL.v>"

    set ::env(CLOCK_PORT) <Clock port name if it exists>
    set ::env(CLOCK_PERIOD) <Desired clock period>

Then you can add any other configurations as you see fit to get the desired DRC/LVS clean
outcome.

After that, run the following command from your ``<your_user_project_root>/openlane/``:

.. code:: bash

    make <your design directory name>

Then, follow the instructions given in Option 2.

**NOTE:**

      You might have other macros inside your design. In which case,
      you may need to have some special power configurations. This is covered
      `here <https://openlane.readthedocs.io/en/latest/docs/source/hardening_macros.html#power-grid-pdn>`__.

Option 2: Flattening your design with the wrapper
------------------------------------------------

#. Add your design to the RTL of the
   `user_project_wrapper <https://github.com/efabless/caravel_user_project/blob/main/verilog/rtl/user_project_wrapper.v>`__.

#. Modify the configuration file `here <https://github.com/efabless/caravel_user_project/blob/main/openlane/user_project_wrapper/config.tcl>`__ to include any extra
   files you may need. Make sure to change these accordingly:

   .. code:: tcl

      set ::env(CLOCK_NET) "mprj.clk"
      set ::env(VERILOG_FILES) " \
            $script_dir/../../verilog/rtl/defines.v \
            $script_dir/../../verilog/rtl/user_project_wrapper.v"

      set ::env(VERILOG_FILES_BLACKBOX) " \
            $script_dir/../../verilog/rtl/defines.v \
            $script_dir/../../verilog/rtl/user_proj_example.v"

      set ::env(EXTRA_LEFS) " \
         $script_dir/../../lef/user_proj_example.lef"

      set ::env(EXTRA_GDS_FILES) " \
         $script_dir/../../gds/user_proj_example.gds"


#. If your design has standard cells then you need to modify the
   configuration file `here <https://github.com/efabless/caravel_user_project/blob/main/openlane/user_project_wrapper/config.tcl>`__ to
   remove or change these configs accordingly:

   .. code:: tcl

       # The following is because there are no std cells in the example wrapper project.
       set ::env(SYNTH_TOP_LEVEL) 1
       set ::env(PL_RANDOM_GLB_PLACEMENT) 1
       set ::env(PL_OPENPHYSYN_OPTIMIZATIONS) 0
       set ::env(DIODE_INSERTION_STRATEGY) 0
       set ::env(FILL_INSERTION) 0
       set ::env(TAP_DECAP_INSERTION) 0
       set ::env(CLOCK_TREE_SYNTH) 0

#. Remove this line
   ``set ::env(MACRO_PLACEMENT_CFG) $script_dir/macro.cfg`` from the
   configuration file `here <https://github.com/efabless/caravel_user_project/blob/main/openlane/user_project_wrapper/config.tcl>`__
   entirely if you have no macros. Alternatively, if you do have macros
   inside your design, then control their placement by modifying `this
   file <https://github.com/efabless/caravel_user_project/blob/main/openlane/user_project_wrapper/macro.cfg>`__

#. Run your design through the flow: ``make user_project_wrapper``

#. You may want to take a look at the `Extra
   Pointers <#extra-pointers>`__ to apply any necessary changes to the
   interactive script.

#. Re-iterate until you have what you want.

**NOTE:**

    In both cases you might have other macros inside your design.
    In which case, you may need to have some special power configurations.
    This is covered `here <https://openlane.readthedocs.io/en/latest/docs/source/hardening_macros.html#power-grid-pdn>`__.

**WARNING:**

    Don't change the size or the pin order!


Extra Pointers
--------------

-  The OpenLANE documentation should cover everything you might need to
   create your design. You can find that
   `here <https://openlane.readthedocs.io/en/latest/>`__.
-  The OpenLANE `FAQs <https://github.com/efabless/openlane/wiki>`__ can
   guide through your troubles.
-  `Here <https://openlane.readthedocs.io/en/latest/configuration/README.html>`__
   you can find all the configurations and how to use them.
-  `Here <https://openlane.readthedocs.io/en/latest/docs/source/advanced_readme.html>`__
   you can learn how to write an interactive script.
-  `Here <https://openlane.readthedocs.io/en/latest/docs/source/OpenLANE_commands.html>`__
   you can find a full documentation for all OpenLANE commands.
-  `This
   documentation <https://openlane.readthedocs.io/en/latest/regression_results/README.html>`__
   describes how to use the exploration script to achieve an LVS/DRC
   clean design.
-  `This
   documentation <https://openlane.readthedocs.io/en/latest/docs/source/hardening_macros.html>`__
   walks you through hardening a macro and all the decisions you should
   make.