[U-Boot] Code Structure and API functionality of U-Boot

[chandan mohanty]

Hi,
 I am a new member to u-boot mail list.
  I have the source code of u-boot downloaded.I am aware that /boot,/board,/driver,include/config are the directory of imprtance.
 
I am trying to read the code.
 
1.I see that there are lots of other files and lots of APIs in the above direcories.Can some one  describe/explain which API,which file does what operation say for ARM boards.
 
Any document/book suggestion on U-BOOT will be also helpfull on understanding the API functionality.
 
2.Suppose I want to debug the U-Boot code.Should I use Abatron BDI2000 hardware debugger ? OR is there any other method available?(I suppose I can not use gdb/kgdb)
 
Regards
Chandan