I'm looking for ideas/suggestions on a good way to track registers and sub registers for a driver crate. I would like to be able to use named values and restrict sub register values to their parent register. 

Example: this works great for single level registers
```
#[non_exhaustive]
struct Regs;

impl Regs {
    pub const REG1: u8 = 0x00;
    pub const REG2: u8 = 0x21;
    pub const REG3: u8 = 0x36;
}
```

Is there a preferred / idiomatic structure for something like this?