Re: [PATCH v7 1/4] rust: i2c: add basic I2C device and driver abstractions

[Danilo Krummrich]

On Mon Nov 10, 2025 at 10:25 PM AEDT, Igor Korotin wrote:
> diff --git a/rust/kernel/i2c.rs b/rust/kernel/i2c.rs
> new file mode 100644
> index 000000000000..41ef7c65c555
> --- /dev/null
> +++ b/rust/kernel/i2c.rs
> @@ -0,0 +1,425 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +//! I2C Driver subsystem
> +
> +// I2C Driver abstractions.
> +use crate::{
> +    acpi, container_of, device,
> +    device_id::{RawDeviceId, RawDeviceIdIndex},
> +    driver,
> +    error::*,
> +    of,
> +    prelude::*,
> +    types::{AlwaysRefCounted, Opaque},
> +};
> +
> +use core::{marker::PhantomData, ptr::NonNull};

Please use kernel "vertical style" [1].

[1] https://docs.kernel.org/rust/coding-guidelines.html#imports

Please also run ./scripts/checkpatch.pl on all patches, there are a few warnings
to address.

> +
> +/// An I2C device id table.
> +#[repr(transparent)]
> +#[derive(Clone, Copy)]
> +pub struct DeviceId(bindings::i2c_device_id);
> +
> +impl DeviceId {
> +    const I2C_NAME_SIZE: usize = 20;
> +
> +    /// Create a new device id from an I2C 'id' string.
> +    #[inline(always)]
> +    pub const fn new(id: &'static CStr) -> Self {
> +        build_assert!(
> +            id.len_with_nul() <= Self::I2C_NAME_SIZE,
> +            "ID exceeds 20 bytes"
> +        );
> +        let src = id.as_bytes_with_nul();
> +        // Replace with `bindings::acpi_device_id::default()` once stabilized for `const`.
> +        // SAFETY: FFI type is valid to be zero-initialized.
> +        let mut i2c: bindings::i2c_device_id = unsafe { core::mem::zeroed() };

You can use pin_init::zeroed() for this.

> +        let mut i = 0;
> +        while i < src.len() {
> +            i2c.name[i] = src[i];
> +            i += 1;
> +        }
> +
> +        Self(i2c)
> +    }
> +}