process autput messages from cat dev/tty/msg through c code via interrupt

hi, I'm working on stm32 mp1, and a 2 core, on one side there is linux and on the other side a mcu, now to communicate the two processors have a common memory. in the specific case I'm sending variables from the mcu to the linux processor, to console these variables on Linux ,I can view them with cat /dev/tty/msg and the buffer goes out to the console. my problem is using interrupt in c code to capture these variables, store them and process them, could someone give me a little code in c (example a scanf inside sig_handle), thanks