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Mon, 10 Nov 2025 03:24:42 -0800 (PST) Received: from Vasilio.Home ([176.26.203.25]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47778daf2c3sm88877575e9.10.2025.11.10.03.24.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Nov 2025 03:24:41 -0800 (PST) From: Igor Korotin To: Miguel Ojeda , Alex Gaynor , Wolfram Sang Cc: Boqun Feng , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Greg Kroah-Hartman , Viresh Kumar , Asahi Lina , Wedson Almeida Filho , Alex Hung , Tamir Duberstein , Xiangfei Ding , linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-i2c@vger.kernel.org Subject: [PATCH v7 0/4] rust: i2c: Add basic I2C driver abstractions Date: Mon, 10 Nov 2025 11:24:37 +0000 Message-ID: <20251110112437.50405-1-igor.korotin.linux@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 --------- 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, 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` 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` instead of `&I2cAdapter`. - Remove `TryFrom> for I2cAdapter` (unused; to be reintroduced in a later I2C series). - Remove `AsRef> for I2cAdapter` (unused; to be reintroduced in a later I2C series). - Add `AsRef for I2cAdapter`. - Use i2c_get/put_adapter instead of get/put_device for `AlwaysRefCounted`. - 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 crate::types::AlwaysRefCounted for Device` 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` 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`. - 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 | 576 ++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 2 + samples/rust/Kconfig | 23 ++ samples/rust/Makefile | 2 + samples/rust/rust_driver_i2c.rs | 69 ++++ samples/rust/rust_i2c_client.rs | 142 ++++++++ 8 files changed, 824 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: 8f3d55856900d0fd87aa8f4f2cac10320485dd38 -- 2.43.0