[U-Boot] DDR initialization

Hi all, How do i go about the SDRAM/DDR initialization on my board. IS the function partitoned or is it just done in a single place. I would think that board specifc dram_init is just a generic function. There has to be a specific place where the SDRAM controller is told about the DRR/SDRAM. Is the porting documented somewhere or are there any good example to follow to stick to U-boot conventions.

Please enlighten me.

Thanks & Regards, ALfred