SOLVED: Once you do insmod, new file is created under /dev/input, in my case it was event0 file. In order to test the functionality, you can do evtest input0. This file can be used from a userspace program in the following way:
struct input_event ev;
FILE* fd = open("/dev/input/event0", O_RDWR);
while(1)
{
int count = read(fd, &ev, sizeof(struct input_event);
for(int i = 0; i < (int)count / sizeof(struct input_event); i++)
{
if(EV_KEY == ev.type) // printf ...
if(EV_ABS == ev.type) // printf ...
}
}
Hope this will help somebody because I feel like this isn't covered enough in Documentation.