You are in the right place, but first you need to figure out if you have the pi2 with the armv7 or with the armv8. then what mode do you want 32 or 64 bit (if the armv8), HYP, SVC, etc...Then from there you can determine how exceptions work. The folks here are very well versed. I have a selection of examples to try to cover the combinations but perhaps dont have every combination. But it should get you started or started down the right documentation or question path.
DOH! I thought you were saying blinker04. uart04 in the top level directory is pi1 only look at the addresses:
#define GPFSEL1 0x20200004
#define GPSET0 0x2020001C
#define GPCLR0 0x20200028
the pi2 and pi3 are 0x3Fxxxxxx not 0x20xxxxxx.
eww actually uart04 has interrupts, so it is a double problem. should work mostly on a pi-zero but go back to what I was saying above about architecture and modes and how you boot, etc. that leads you into the how to deal with events/interrupts. then of course the addresses for the pi2 and pi3 are 0x3Fxxxxxx based wherever you see 0x20xxxxxx and the led if any (on a gpio) are on some other pin.