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Date: Tue, 11 Nov 2025 19:10:11 +1100
Message-Id: <DE5POG7G08QG.LT9YJCA0IN11@kernel.org>
Subject: Re: [PATCH v7 1/4] rust: i2c: add basic I2C device and driver
 abstractions
Cc: "Miguel Ojeda" <ojeda@kernel.org>, "Alex Gaynor"
 <alex.gaynor@gmail.com>, "Wolfram Sang" <wsa+renesas@sang-engineering.com>,
 "Boqun Feng" <boqun.feng@gmail.com>, "Gary Guo" <gary@garyguo.net>,
 =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>, "Benno Lossin"
 <lossin@kernel.org>, "Andreas Hindborg" <a.hindborg@kernel.org>, "Alice
 Ryhl" <aliceryhl@google.com>, "Trevor Gross" <tmgross@umich.edu>, "Greg
 Kroah-Hartman" <gregkh@linuxfoundation.org>, "Viresh Kumar"
 <viresh.kumar@linaro.org>, "Asahi Lina" <lina+kernel@asahilina.net>,
 "Wedson Almeida Filho" <wedsonaf@gmail.com>, "Alex Hung"
 <alex.hung@amd.com>, "Tamir Duberstein" <tamird@gmail.com>, "Xiangfei Ding"
 <dingxiangfei2009@gmail.com>, <linux-kernel@vger.kernel.org>,
 <rust-for-linux@vger.kernel.org>, <linux-i2c@vger.kernel.org>
To: "Igor Korotin" <igor.korotin.linux@gmail.com>
From: "Danilo Krummrich" <dakr@kernel.org>
References: <20251110112437.50405-1-igor.korotin.linux@gmail.com>
 <20251110112507.50525-1-igor.korotin.linux@gmail.com>
In-Reply-To: <20251110112507.50525-1-igor.korotin.linux@gmail.com>

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 war=
nings
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 =3D 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() <=3D Self::I2C_NAME_SIZE,
> +            "ID exceeds 20 bytes"
> +        );
> +        let src =3D id.as_bytes_with_nul();
> +        // Replace with `bindings::acpi_device_id::default()` once stabi=
lized for `const`.
> +        // SAFETY: FFI type is valid to be zero-initialized.
> +        let mut i2c: bindings::i2c_device_id =3D unsafe { core::mem::zer=
oed() };

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

> +        let mut i =3D 0;
> +        while i < src.len() {
> +            i2c.name[i] =3D src[i];
> +            i +=3D 1;
> +        }
> +
> +        Self(i2c)
> +    }
> +}