Hi @Sara_Ahmed
We do not provide the source code of HSE FW if you want a custom HSE FW, premium packages are custom firmware releases that contain customer-specific requirements. Please contact your NXP sales representative for more details.
Regarding HSE documentation, is under NDA (Non-Disclosure Agreement) and is classified as Secure Files, so, the information is not public, and I am not able to share it due to the security levels.
You need a valid NDA to request access. If you cannot access Secure Files, please follow the instructions listed at NXP SECURE ACCESS RIGHTS FIRST-TIME USER REGISTRATION GUIDE.
B.R.
VaneB