[U-Boot] U-boot -Modifying boot sequence on a ARM based board

Hi all, What is the general boot sequence for u-boot. IIRC, its the cpu specific start followed by board specfic stuff, then general init stuff (like misc_init_f) and then the common stuff. The reason i am asking this i want to inject my own boot path based on the presence of certain boot peripherals. I want to override the "boot_args" with my custom-defined bootargs and then execute "bootm" from a predefined RAM address. I want to know which is the most appropriate place for soing this. I was initilally thinking it would end up in the board specific code(board/<boardname>.c) but i am a bit confused when i read the main/common code.

Please let me your recommendations on this.

-Alfred.