tree 23b790d658d0cdd1ec0dd1c339171ceeb8a91a18
parent e9d493a4a741f26810f1493116307f65e69417a2
author Tim 'mithro' Ansell <tansell@google.com> 1593623543 -0700
committer Tim 'mithro' Ansell <me@mith.ro> 1605114095 -0800

Add the standard cells as submodules.

They are being added as submodules from the
https://foss-eda-tools.googlesource.com/ repository due to their large
size. People are encouraged to only initialize and clone the submodules
needed for their designs.

 * [`sky130_fd_sc_hvl`](https://github.com/google/skywater-pdk/tree/master/libraries/sky130_fd_sc_hvl) -
   "High voltage" digital standard cells provided by the SkyWater
   foundry.

 * [`sky130_fd_sc_lp`](https://github.com/google/skywater-pdk/tree/master/libraries/sky130_fd_sc_hp) -
   "Low power" digital standard cells provided by the SkyWater foundry.

Signed-off-by: Tim 'mithro' Ansell <tansell@google.com>