mbedtls/docs/proposed/psa-driver-wrappers-codegen-migration-guide.md

Migrating to an auto genrated psa_crypto_driver_wrappers.c file
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**This is a specification of work in progress. The implementation is not yet merged into Mbed TLS.**

This document describes how to migrate to the auto generated psa_crypto_driver_wrappers.c file.
It is meant to give the library user migration guidelines while the Mbed TLS project tides over multiple minor revs of version 1.0, after which this will be merged into psa-driver-interface.md.

## Introduction

The design of the Driver Wrappers code generation is based on the design proposal https://github.com/ARMmbed/mbedtls/pull/5067
During the process of implementation there might be minor variations wrt versioning and broader implementation specific ideas, but the design remains the same.

## Prerequisites

Python3 and Jinja2 rev 2.10.1

## Feature Version

1.0

### What's critical for a migrating user

The Driver Wrapper auto generation project is designed to use a python templating library ( Jinja2 ) to render templates based on drivers that are defined using a Driver descrioption JSON file(s).

While that is the larger goal, for version 1.0 here's what's changed

#### What's changed

(1) psa_crypto_driver_wrappers.c will from this point on be auto generated.
(2) The auto generation is based on the template file at scripts/data_files/driver_templates/psa_crypto_driver_wrappers.c.jinja.
(3) So while all driver wrapper templating support is yet to come in, the library user will need to patch into the template file as needed.