Re: [PATCH v6 2/3] rust: i2c: add manual I2C device creation abstractions

[Danilo Krummrich <dakr@kernel.org>]

On 10/5/25 12:23 PM, Igor Korotin wrote:
> +impl Registration {
> +    /// The C `i2c_new_client_device` function wrapper for manual I2C client creation.
> +    pub fn new(i2c_adapter: &I2cAdapter, i2c_board_info: &I2cBoardInfo) -> Result<Self> {
> +        // SAFETY: the kernel guarantees that `i2c_new_client_device()` returns either a valid
> +        // pointer or NULL. `from_err_ptr` separates errors. Following `NonNull::new` checks for NULL.
> +        let raw_dev = from_err_ptr(unsafe {
> +            bindings::i2c_new_client_device(i2c_adapter.as_raw(), i2c_board_info.as_raw())
> +        })?;
> +
> +        let dev_ptr = NonNull::new(raw_dev).ok_or(ENODEV)?;
> +
> +        Ok(Self(dev_ptr))
> +    }
> +}

I wonder if we want to ensure that a Registration can't out-live the driver that
registers the I2C client device.

This should only ever be called by drivers bound to more complex devices, so if
the parent driver is unbound I don't think I2C client device registered by this
driver should be able to survive.

Hence, I think Registration::new() should return
impl PinInit<Devres<Self>, Error> instead.