U-Boot. Where does it all begin?

U-Boot. Where does it all begin?

Newbie question here.
I'm looking at a u-boot boardfile, and it has many functions in it. For
example; board_mmc_init(), enet_board_init(), setup_splash_img(), etc.
Most of these functions don't get called from within the boardfile. They
get called from somewhere else. But I can't figure out where.
In Linux kernel boardfiles there's a machine structure. In there we might
have .init_machine = myboard_init. Then myboard_init(void) will call other
functions which will in turn call other functions. I find this style easy
to read.
My question is; does u-boot have an equivalent of .init_machine? Where do
I look to see where everything 'starts'? Who calls all those loose
functions thrown together inside a u-boot boardfile?
-Andy