It may be useful to build a Zephyr OS-based EC for a device which already has a CrOS EC device build, for the purposes of demonstrating the feasibility of Zephyr OS.
This document is a work-in-progress list of tricks & tools that may be useful to you.
Initially, you'll want to get a basic UART functioning with nothing but a shell and some basic console commands.
An example CL to do this for Lazor can be found here.
After you have UART functioning, GPIOs can be an easy target to start unblocking further features.
We have a very ugly program to auto-generate the GPIO DTS based on gpio.inc for the existing board. You can find it at util/gpios_to_zephyr_dts.c, and instructions are in the file on how to compile and use it. You may have to hand-modify the output.
The resultant CL for Lazor can be found here.
Set CONFIG_PLATFORM_EC_HOSTCMD=y and enable the appropriate host-command interface for your platform (e.g., eSPI).
An example CL for Lazor can be found here.
As long as you get this compiling that should be enough to move to the next step. Further testing of the host command layer will require power sequencing up and going.
For further explanation, check AP-EC communication document.
Next, you can:
TODO(jrosenth): add steps on enabling power sequencing and expand this document.
