There should be one style for regs. Given that arm & vendor docs use all-caps and rust guideline for a static is all-caps, I think that register name should be all-caps. Any objections?

I'm not that sure about getter and setter names though, I've been naming them all-caps in violation of current rust guideline based on the vendor docs. The good point is that registers access stands out in the code, the bad point is that it doesn't look well. Any comments on this?