Have a ATK tool BBT(bad block table) algorithm or sample code for iMX258 ?
You may look at
ADS_Toolkit\AdvancedToolKit1.71_Source_STD\device_program\flash\nand_flash\src\nand_bbt.c
in
https://www.freescale.com/webapp/Download?colCode=IMX_ATK_SOURCE_CODE&appType=license&location=null