Hello Victor Mazin,
If you are using new platform other than LS1021ATWR, as Alexander has suggested, you're recommend to porting from Freescale QorIQ SDK, since it has already included support for LS1021A.
Some steps of porting u-boot including creating configuration file based on ls1021atwr.h, ls1021atwr.c, ddr.c, ls1_rcw.cfg, ls1_pbi.cfg and rebuilding images, porting Linux including creating new file based on mach-ls1021a.c, ls1021a_defconfig, new device tree, and so on. There is application note of U-Boot and Linux porting on T4240 system, although it's not for LS1021A I think it may be also helpful.
http://cache.freescale.com/files/32bit/doc/app_note/AN4814.pdf?fsrch=1&sr=1&pageNum=1
Have a great day,
Lunmin
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