Need Info About MCU

Hi;

I need some info about nokia MCU. Mostly I2C and LCD screen communication parts. How can i access codes in MCU (Flash files). Directly disassembling is OK? or Must i decrypt MCU files. Is there any tool to do this job. I think code part that loading bitmaps will take me to the screen code routines. Any info appreciated.

Note: I am not interested in any phone unlocking stuff. Just need info on flash files and hardware.

Thanks.