MAINTAINERS | 4 +- include/linux/i2c.h | 6 + rust/helpers/helpers.c | 1 + rust/helpers/i2c.c | 15 ++ rust/kernel/bits.rs | 57 ++++++++ rust/kernel/i2c.rs | 254 ++------------------------------- rust/kernel/i2c/adapter.rs | 200 ++++++++++++++++++++++++++ rust/kernel/i2c/algo.rs | 300 +++++++++++++++++++++++++++++++++++++++ rust/kernel/i2c/client.rs | 284 ++++++++++++++++++++++++++++++++++++ samples/rust/Kconfig | 12 ++ samples/rust/Makefile | 1 + samples/rust/rust_driver_i2c.rs | 10 +- samples/rust/rust_i2c_adapter.rs | 170 ++++++++++++++++++++++ samples/rust/rust_i2c_client.rs | 15 +- 14 files changed, 1069 insertions(+), 260 deletions(-)
This patch series extend the existing I2C functionality with:
- Abstractions allowing to implement I2C algorithms used by I2C adapters;
- Abstractions allowing to create and add new I2C adapters;
- Safe wrappers upon I2C and SMbus transferring C API: read/write
bytes/words/byte arrays.
The patch series contains additional new sample driver `rust_i2c_adapter`
presenting the new functionality.
Patch series depend on
message-id: <20260107103511.570525-1-dakr@kernel.org>
Signed-off-by: Igor Korotin <igor.korotin.linux@gmail.com>
---
Igor Korotin (5):
rust: i2c: split client and adapter code into separate files
rust: bits: add define_flags macro
rust: i2c: Add I2C Adapter registration abstractions
rust: i2c: add I2C wrappers
samples: rust: add Rust I2C adapter registration sample
MAINTAINERS | 4 +-
include/linux/i2c.h | 6 +
rust/helpers/helpers.c | 1 +
rust/helpers/i2c.c | 15 ++
rust/kernel/bits.rs | 57 ++++++++
rust/kernel/i2c.rs | 254 ++-------------------------------
rust/kernel/i2c/adapter.rs | 200 ++++++++++++++++++++++++++
rust/kernel/i2c/algo.rs | 300 +++++++++++++++++++++++++++++++++++++++
rust/kernel/i2c/client.rs | 284 ++++++++++++++++++++++++++++++++++++
samples/rust/Kconfig | 12 ++
samples/rust/Makefile | 1 +
samples/rust/rust_driver_i2c.rs | 10 +-
samples/rust/rust_i2c_adapter.rs | 170 ++++++++++++++++++++++
samples/rust/rust_i2c_client.rs | 15 +-
14 files changed, 1069 insertions(+), 260 deletions(-)
---
base-commit: a7c013f779530190d0c1e1aa5e7c8a61f0bd479e
change-id: 20260131-i2c-adapter-d38d330c4c25
prerequisite-message-id: <20260107103511.570525-1-dakr@kernel.org>
prerequisite-patch-id: 6e4d28a06d842ddfc7db82f410532a35b8fe317d
prerequisite-patch-id: 9739295d85b688257fca29be1e1217a05a69c9e7
prerequisite-patch-id: 78eaed3746a40713f44f13508fcf43653b0a4528
prerequisite-patch-id: 99f1881bc896896297a903affcfa4f62cab1a307
prerequisite-patch-id: ea8baa9d648f1178d6f39d140b98bddf3c183f6f
prerequisite-patch-id: f8a9e049d204bde04e80151a67dfff5ec2633e7a
Best regards,
--
Igor Korotin <igor.korotin.linux@gmail.com>
(Cc: Bartosz, Greg, Rafael, driver-core) On Sat Jan 31, 2026 at 3:12 PM CET, Igor Korotin via B4 Relay wrote: > This patch series extend the existing I2C functionality with: > - Abstractions allowing to implement I2C algorithms used by I2C adapters; > - Abstractions allowing to create and add new I2C adapters; > - Safe wrappers upon I2C and SMbus transferring C API: read/write > bytes/words/byte arrays. > > The patch series contains additional new sample driver `rust_i2c_adapter` > presenting the new functionality. The i2c_adapter code on the C side has some lifetime issues, Bartosz looks into resolving. My biggest concern is that struct i2c_adapter is a bus device implementation, but does not use the reference count of the embedded struct device. Instead, I2C bus drivers embedd the i2c_adapter in their driver specific structure, which is typically freed in the I2C bus driver's remove() callback. This violates struct device reference counts. Until this is fixed, the Rust abstractions should probably work around this, to subsequent painful rework. > Patch series depend on > message-id: <20260107103511.570525-1-dakr@kernel.org> > > Signed-off-by: Igor Korotin <igor.korotin.linux@gmail.com> > --- > Igor Korotin (5): > rust: i2c: split client and adapter code into separate files > rust: bits: add define_flags macro > rust: i2c: Add I2C Adapter registration abstractions > rust: i2c: add I2C wrappers > samples: rust: add Rust I2C adapter registration sample > > MAINTAINERS | 4 +- > include/linux/i2c.h | 6 + > rust/helpers/helpers.c | 1 + > rust/helpers/i2c.c | 15 ++ > rust/kernel/bits.rs | 57 ++++++++ > rust/kernel/i2c.rs | 254 ++------------------------------- > rust/kernel/i2c/adapter.rs | 200 ++++++++++++++++++++++++++ > rust/kernel/i2c/algo.rs | 300 +++++++++++++++++++++++++++++++++++++++ > rust/kernel/i2c/client.rs | 284 ++++++++++++++++++++++++++++++++++++ > samples/rust/Kconfig | 12 ++ > samples/rust/Makefile | 1 + > samples/rust/rust_driver_i2c.rs | 10 +- > samples/rust/rust_i2c_adapter.rs | 170 ++++++++++++++++++++++ > samples/rust/rust_i2c_client.rs | 15 +- > 14 files changed, 1069 insertions(+), 260 deletions(-) > --- > base-commit: a7c013f779530190d0c1e1aa5e7c8a61f0bd479e > change-id: 20260131-i2c-adapter-d38d330c4c25 > prerequisite-message-id: <20260107103511.570525-1-dakr@kernel.org> > prerequisite-patch-id: 6e4d28a06d842ddfc7db82f410532a35b8fe317d > prerequisite-patch-id: 9739295d85b688257fca29be1e1217a05a69c9e7 > prerequisite-patch-id: 78eaed3746a40713f44f13508fcf43653b0a4528 > prerequisite-patch-id: 99f1881bc896896297a903affcfa4f62cab1a307 > prerequisite-patch-id: ea8baa9d648f1178d6f39d140b98bddf3c183f6f > prerequisite-patch-id: f8a9e049d204bde04e80151a67dfff5ec2633e7a > > Best regards, > -- > Igor Korotin <igor.korotin.linux@gmail.com>
On Sat, 31 Jan 2026 15:26:22 +0100, Danilo Krummrich <dakr@kernel.org> said: > (Cc: Bartosz, Greg, Rafael, driver-core) > > On Sat Jan 31, 2026 at 3:12 PM CET, Igor Korotin via B4 Relay wrote: >> This patch series extend the existing I2C functionality with: >> - Abstractions allowing to implement I2C algorithms used by I2C adapters; >> - Abstractions allowing to create and add new I2C adapters; >> - Safe wrappers upon I2C and SMbus transferring C API: read/write >> bytes/words/byte arrays. >> >> The patch series contains additional new sample driver `rust_i2c_adapter` >> presenting the new functionality. > > The i2c_adapter code on the C side has some lifetime issues, Bartosz looks into > resolving. > > My biggest concern is that struct i2c_adapter is a bus device implementation, > but does not use the reference count of the embedded struct device. > > Instead, I2C bus drivers embedd the i2c_adapter in their driver specific > structure, which is typically freed in the I2C bus driver's remove() callback. > Correct. > This violates struct device reference counts. > What's currently done in order to not crash is: we wait forever until all users release their references[1]. > Until this is fixed, the Rust abstractions should probably work around this, to > subsequent painful rework. > The rework of the C part will be long an painful already. I estimated the work will take at least a year. More info here[2]. Bart [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/i2c/i2c-core-base.c#n1814 [2] https://lore.kernel.org/all/aWYYZEPX-_1GfQtL@ninjato/
Hello Danilo On 1/31/2026 2:26 PM, Danilo Krummrich wrote: > (Cc: Bartosz, Greg, Rafael, driver-core) > > On Sat Jan 31, 2026 at 3:12 PM CET, Igor Korotin via B4 Relay wrote: >> This patch series extend the existing I2C functionality with: >> - Abstractions allowing to implement I2C algorithms used by I2C adapters; >> - Abstractions allowing to create and add new I2C adapters; >> - Safe wrappers upon I2C and SMbus transferring C API: read/write >> bytes/words/byte arrays. >> >> The patch series contains additional new sample driver `rust_i2c_adapter` >> presenting the new functionality. > > The i2c_adapter code on the C side has some lifetime issues, Bartosz looks into > resolving. > > My biggest concern is that struct i2c_adapter is a bus device implementation, > but does not use the reference count of the embedded struct device. > > Instead, I2C bus drivers embedd the i2c_adapter in their driver specific > structure, which is typically freed in the I2C bus driver's remove() callback. > > This violates struct device reference counts. > > Until this is fixed, the Rust abstractions should probably work around this, to > subsequent painful rework. just to clarify what is currently implemented on the Rust side. The Rust I2cAdapter is required to be bound to a parent Device<Bound>. The implementation keeps a reference to the embedded struct device inside struct i2c_adapter for the entire lifetime of the Rust adapter, so its lifetime is tied to the device model. I am not entirely sure which specific lifetime or refcounting scenario you are referring to. If you have a concrete case in mind where this would still be problematic, could you please point it out? Cheers Igor
On Sun Feb 8, 2026 at 1:34 PM CET, Igor Korotin wrote: > Hello Danilo > > On 1/31/2026 2:26 PM, Danilo Krummrich wrote: >> (Cc: Bartosz, Greg, Rafael, driver-core) >> >> On Sat Jan 31, 2026 at 3:12 PM CET, Igor Korotin via B4 Relay wrote: >>> This patch series extend the existing I2C functionality with: >>> - Abstractions allowing to implement I2C algorithms used by I2C adapters; >>> - Abstractions allowing to create and add new I2C adapters; >>> - Safe wrappers upon I2C and SMbus transferring C API: read/write >>> bytes/words/byte arrays. >>> >>> The patch series contains additional new sample driver `rust_i2c_adapter` >>> presenting the new functionality. >> >> The i2c_adapter code on the C side has some lifetime issues, Bartosz looks into >> resolving. >> >> My biggest concern is that struct i2c_adapter is a bus device implementation, >> but does not use the reference count of the embedded struct device. >> >> Instead, I2C bus drivers embedd the i2c_adapter in their driver specific >> structure, which is typically freed in the I2C bus driver's remove() callback. >> >> This violates struct device reference counts. >> >> Until this is fixed, the Rust abstractions should probably work around this, to >> subsequent painful rework. > > just to clarify what is currently implemented on the Rust side. > > The Rust I2cAdapter is required to be bound to a parent Device<Bound>. > The implementation keeps a reference to the embedded struct device > inside struct i2c_adapter for the entire lifetime of the Rust adapter, > so its lifetime is tied to the device model. > > I am not entirely sure which specific lifetime or refcounting scenario > you are referring to. If you have a concrete case in mind where this > would still be problematic, could you please point it out? The implementation on the C side does not consider the reference count of the embedded struct device, which is not correct.
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