Re: [PATCH v8 0/4] rust: i2c: Add basic I2C driver abstractions

[Markus Probst <markus.probst@posteo.de>]

add me to cc please.

My led driver currently relies on the i2c bindings.

Thanks
- Markus Probst

[1]
https://lore.kernel.org/rust-for-linux/20251008181027.662616-1-markus.probst@posteo.de/

On Sun, 2025-11-16 at 16:21 +0000, Igor Korotin wrote:
> This patch series lays the groundwork for writing Linux I2C drivers in 
> Rust by:
> 
>  1. Core abstractions 
>     Introduce `i2c::I2cClient`, `i2c::I2cAdapter`, `i2c::Driver` and 
>     built on the existing `struct i2c_client`, `struct i2c_adapter` 
>     and `struct i2c_driver`, with safe Rust wrappers around probe, 
>     transfer, and teardown logic.
> 
>  2. Manual device creation  
>     Provide an API to register an I2C device at runtime from Rust using
>     `I2cBoardInfo` and `I2cAdapter`, including automatic cleanup when 
>     the driver unloads.
> 
>  3. Sample I2C driver (legacy table, OF & ACPI)  
>     Add `rust_driver_i2c`, a sample that:
>       - binds to an I2C client via: 
>         - legacy I2C-ID table, 
>         - Open Firmware (device-tree) compatible strings, or
>         - ACPI IDs.
>  4. Sample I2C client registration (OF & ACPI)
>     Add `rust_i2c_client`, a sample that:
>       - binds to a platform parent device using OF/ACPI table
>       - registers new I2C client bound to the parent platform device
>         using `i2c::Registration::new()`
>       - destroyes the I2C client device on exit.
> 
> Together, these four patches:
> 
> - Establish the essential Rust traits and types for I2C drivers.
> - Enable driver binding via legacy ID table, device-tree (OF), or ACPI
> - Enable manual device creation at runtime.
> - Ship a samples showing typical usage 
> 
> Igor Korotin (4):
>   rust: i2c: add basic I2C device and driver abstractions
>   rust: i2c: add manual I2C device creation abstractions
>   samples: rust: add Rust I2C sample driver
>   samples: rust: add Rust I2C client registration sample
> 
> Changelog
> ---------
> v8:
>  - Rebase commits on top of [1]
>  - Applied kernel vertical style [2] 
>  - Replace core::mem::zeroed() with pin_init::zeroed()
>  - Rename `I2cAdapter::get_nr` to `I2cAdapter::index`
>  - fixed some minor format issues
>  - Link to v7: [3]
> 
>  [1] https://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core.git/log/?h=driver-core-next
>  [2] https://docs.kernel.org/rust/coding-guidelines.html#imports
>  [3] https://lore.kernel.org/rust-for-linux/20251110112437.50405-1-igor.korotin.linux@gmail.com/
> 
> v7:
>  - Rebase and update `i2c::Driver::probe` function based on patch 
>    series [1].
>  - use `i2c::Driver::unbind` instead of `drop` in 
>    `i2c::Adapter::remove_callback`
>  - Implement and use `i2c::Driver::unbind` for I2C SampleDriver
>    instead of Drop.
>  - `i2c::Registration::new` requires a parent device to which a new
>    I2C client will be bound. 
>  - `i2c::Registration::new` returns `impl PinInit<Devres<Self>, Error>`
>  - The existing rust_driver_i2c sample has been split into two:
>    `rust_driver_i2c`, which demonstrates the implementation of an I2C 
>    driver, and `rust_i2c_client`, which demonstrates registering a new 
>    I2C client bound to a parent platform device.
>  - Link to v6: [2]
> 
>  [1] https://lore.kernel.org/all/20251016125544.15559-1-dakr@kernel.org/
>  [2] https://lore.kernel.org/rust-for-linux/20251005102226.41876-1-igor.korotin.linux@gmail.com/ 
> 
> v6:
>  - Add implementation of unbind for `i2c::Driver` trait;
>  - Add argument `Pin<&Self>` to `i2c::Driver::shutdown` method; 
>  - Adjust usage of `i2c::Driver::shutdown` in 
>    `i2c::Adapter::shutdown_callback` in `i2c::Driver` trait code 
>    example and in rust_driver_i2c code;
>  - Remove dummy AsRef implementation for I2cAdapter. Adjust code 
>    in rust_driver_i2c;
>  - Add `i2c::I2cAdapter::get_nr` method that returns I2cAdapter index;
>  - Optimize unsafe sections in inc_ref/dec_ref in AlwaysRefCounted 
>    for I2cAdapter implementation;
>  - Remove unnecessary Drop implementation for I2cAdapter, because 
>    I2cAdapter is always a reference;
>  - Remove unnecessary type definition `Ops<T>` in rust_driver_i2c
>  - Simplify call of `i2c::I2cAdapter::get` in `try_pin_init!` macro 
>    for rust_driver_i2c
>  - Link to v5: https://lore.kernel.org/rust-for-linux/20250911154717.96637-1-igor.korotin.linux@gmail.com/ 
> v5:
>  - Rename missed pdev variables to idev (thanks to Daniel).
>  - Import `crate::device_id::RawDeviceIdIndex` and 
>    `crate::types::AlwaysRefCounted` in i2c.rs.
>  - Switch dev_dbg to dev_info in the sample I2C driver messages.
>  - Make `I2cAdapter::get()` return `ARef<I2cAdapter>` instead of 
>    `&I2cAdapter`.
>  - Remove `TryFrom<device::Device<Ctx>> for I2cAdapter<Ctx>` (unused; 
>    to be reintroduced in a later I2C series).
>  - Remove `AsRef<device::Device<Ctx>> for I2cAdapter<Ctx>` (unused; 
>    to be reintroduced in a later I2C series).
>  - Add `AsRef<I2cAdapter> for I2cAdapter<Ctx>`.
>  - Use i2c_get/put_adapter instead of get/put_device for 
>    `AlwaysRefCounted<I2cAdapter>`.
>  - Update safety comment for `unsafe impl Sync for Registration {}`.
>  - Tweak comment for `I2cBoardInfo::new`.
>  - Adjust build-time assertion message in `Adapter::register`.
>  - Link to v4: https://lore.kernel.org/rust-for-linux/20250820151427.1812482-1-igor.korotin.linux@gmail.com/ 
> v4:
>  - Renamed `i2c::I2cAdapterRef` to `i2c::I2cAdapter`.
>  - Renamed `i2c::Device` to `i2c::I2cClient` for consistency with 
>    `i2c::I2cAdapter` and to avoid confusion with `i2c::Adapter`
>  - Reworked `i2c::I2cAdapter` to be an Opaque around `i2c_adapter` struct
>  - Implemented AlwaysRefCounted trait for `i2c::I2cAdapter`. 
>  - Fixed numerous comment mistakes and typos all over the code, thanks 
>    to Danilo and Daniel
>  - Got rid of all unwrap() use-cases in i2c.rs and rust_driver_i2c.rs.
>    This covers 0-day kernel panic <202508071027.8981cbd4-lkp@intel.com>
>  - Removed unnecessary casts.
>  - Replaced all addr_of_mut! macros to &raw mut.
>  - In `i2c::Adapter::register` method build assert if all ID tables are 
>    None.
>  - Renamed all pdrv and pdev instances to idrv and idev respectivly 
>  - Implemented an ealry return in `i2c::Adapter::i2c_id_info`
>  - Added all missing Safety comments. 
>  - Removed `unsafe impl<Ctx: device::DeviceContext> crate::types::AlwaysRefCounted for Device<Ctx>` 
>    implementation which came to v3 from v2 by mistake.
>  - Added more details regarding i2c-stub driver usage in rust_driver_i2c
>    comment.
>  - Changed `i2c::I2cAdapter::get` return type from `Option<Self>` to 
>    `Result<&'static Self>`.
>  - Added Daniel Almeida as a reviewer to the "I2C Subsystem [RUST]" entry 
>    in MAINTAINERS, per his offer.
>  - Link to v3: https://lore.kernel.org/rust-for-linux/20250801153742.13472-1-igor.korotin.linux@gmail.com/
> v3: 
>  - removed unnecessary i2c_get_clientdata and i2c_set_clientdata rust 
>    helpers. Using generic accessors implemented in [1] instead.
>  - Reimplemented i2c::DeviceId based on changes in [2].
>  - Using from_result in i2c::Adapter::probe_callback
>  - Using explicit drop() for i2c client private data in 
>    `i2c::Adapter::remove_callback`
>  - replaced device::Device::as_ref() with device::Device::from_raw in 
>    `i2c::Device::as_ref()`. It is renamed in device::Device.
>  - Build Rust I2C only if I2C is built-in
>  - Reimplement overcomplicated trait i2c::DeviceOwned the same way it is 
>    implemented in auxiliary [3].
>  - Merge rust_device_i2c and rust_driver_i2c samples. Resulting 
>    rust_driver_i2c creates pined i2c_client using i2c::Registration::new 
>    and probes newly created i2c_client.
>  - Created a new entry in MAINTAINERS file containing i2c.rs and 
>    rust_driver_i2c.rs in it.
>  - Link to v2: [4] 
> 
>  [1] https://lore.kernel.org/lkml/20250621195118.124245-3-dakr@kernel.org/
>  [2] https://lore.kernel.org/rust-for-linux/20250711040947.1252162-1-fujita.tomonori@gmail.com/
>  [3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/rust/kernel/auxiliary.rs?h=v6.16-rc4#n299
>  [4] https://lore.kernel.org/rust-for-linux/20250704153332.1193214-1-igor.korotin.linux@gmail.com/ 
> 
> v2:
>  - Merged separated ACPI support patches since ACPI-table support is 
>    merged into driver-core-next.
>  - Added I2cAdapterRef and I2cBoardInfo abstractions 
>  - Added DeviceState generic parameter which is used for `i2c::Device`
>    as a sign if the device is created manually
>  - Added `DeviceOwned` abstraction which is a safe reference to a 
>    manually created `i2c::Device<Ctx, state::Owned>`. 
>  - Added Rust manual I2C device creation sample
>  - Link to v1: https://lore.kernel.org/rust-for-linux/20250626174623.904917-1-igor.korotin.linux@gmail.com/
> 
>  MAINTAINERS                     |   9 +
>  rust/bindings/bindings_helper.h |   1 +
>  rust/kernel/i2c.rs              | 589 ++++++++++++++++++++++++++++++++
>  rust/kernel/lib.rs              |   2 +
>  samples/rust/Kconfig            |  23 ++
>  samples/rust/Makefile           |   2 +
>  samples/rust/rust_driver_i2c.rs |  74 ++++
>  samples/rust/rust_i2c_client.rs | 157 +++++++++
>  8 files changed, 857 insertions(+)
>  create mode 100644 rust/kernel/i2c.rs
>  create mode 100644 samples/rust/rust_driver_i2c.rs
>  create mode 100644 samples/rust/rust_i2c_client.rs
> 
> 
> base-commit: ededb7bcdfdbcfbb7af93e3a543165a9553e1683