Struct vs enum to hold register addresses in a Rust hardware driver

struct_vs_enum.md

What are, if any, pros or cons of using a struct vs using an enum to hold register addresses for a device driver? Different authors of such drivers seem to approach it differently. At first sight the struct seems to make more sense, as there is no need to add the function that will return actual u8 values required by the functions. Is there some good reason to use enum here?

struct Register;
impl Register {
    const CTRL_STATUS_2     : u8 = 0x01;
}

/// Clear the timer flag.
pub fn clear_timer_flag(&mut self) -> Result<(), Error<E>> {
    self.clear_register_bit_flag(Register::CTRL_STATUS_2, 0b0001_0000)
}

vs this approach:

pub enum Register {    
    CTRL_STATUS_2 = 0x01,    
}

impl Register {
    pub fn addr(self) -> u8 {
        self as u8
    }
}

/// Clear the timer flag.
pub fn clear_timer_flag(&mut self) -> Result<(), Error<E>> {
    self.clear_register_bit_flag(Register::CTRL_STATUS_2.addr(), 0b0001_0000)
}