I think you have to check the main controller(CPU) on your board. Usually, there will be a hardware timer module integrated into the CPU, or decrementer register implementation in the CPU core.
If there is a hardware timer or DEC register on your CPU, then use it to implement a periodical interrupt(the frequency can be 1000HZ or else). The interrupt handler can notify/wakeup the user-space process to do the necessary real-time work.