Earlycon on IMX serial port

modulename: imx_earlycon.ko

configname: CONFIG_SERIAL_IMX_EARLYCON

Linux Kernel Configuration
└─>Device Drivers
└─>Character devices
└─>Serial drivers
└─>Device Tree and Open Firmware support
└─>Earlycon on IMX serial port
In linux kernel since version 5.1 (release Date: 2019-05-05)  
If you have enabled the earlycon on the Freescale IMX
CPU you can make it the earlycon by answering Y to this option.

source code: