How to write directly to FPGA peripherals from SoC ??

Hi,

I'm working on an Altera Cyclone V SoC. I'm attempting to write directly to FPGA peripherals from my SoC, however, the hwlib library only contains the function alt_write_word, which I understand that this function writes to the cache first before writing it to the main memory. In NIOS II, the built in function IOWR has already configured the memory so that the IOWR function writes directly to the FPGA peripherals. So, my question is, when I'm working with SoC, if the hwlib library doesn't provide such a function, how can I write directly to the FPGA peripherals ? Do I need to configure the memory type or what ?