Middleware for SPI and I2C

I am planning a new project that should include an AM3558 processor -the internals in this chip includes UART, I2C and SPI which I need for my project. Currently I have successfully located an RTOS vendor and tool support that I think can meet what I need. The problem I have is the development of middleware code to access the SPI and I2C - most everything I locate either require register level programming, or it refers to linux. I am looking for some example C code that can build the layer between my code and the hardware.