NXP: Layerscape: add new device types and new feature for booting board from Alternate Bank
This merge request is doing following things:
- Adding 3 new device types (fsl-ls1046a-frwy, fsl-lx2162a-qds, fsl-ls2088a-rdb)
- Adding the new feature for booting the NXP Layerscape boards from Alternate Bank, also modifying device files for using this feature.
What is this Alternate Bank ? On Layerscape boards, we have a mechanism of booting boards from multiple banks. This is done mainly to protect board from getting bricked if wrong images gets flashed on board.
Board is set to boot from a Bank 1 by default (controlled by switches). Now you use this bank also to flash your images, but in case the images are corrupt, board will get bricked and you will need to connect JTAG to recover the board.
So here concept of Alternate Bank boot comes to help. By default board boots from Bank 1, but we will not flash the images on Bank 1, instead we will flash images on Bank 2. After flashing the images, we will boot from Bank 2 with a certain command on u-boot "qixis_reset altbank", "cpld reset altbank", "boot_bank" depending upon the board. With this command, Board boots from the Bank 2 and now we can boot up kernel on board. Since in this case, we have flashed the images on Bank 2 and even if images are corrupt, Bank 2 will get bricked, but since we have set board to boot from Bank 1 by default, Board will still be usable and you can flash the correct images on Bank 2 and get that working.