[PATCH v6 0/3] Rust abstractions for the SPI driver subsystem

[PATCH v6 0/3] Rust abstractions for the SPI driver subsystem

[Shuai Liu]

Changes since v5:
  - validate in `write_then_read()` that the sum of the two buffer
    lengths fits in `u32`: the C core's spi_write_then_read() sums the
    two lengths as `unsigned int` when selecting and sizing its bounce
    buffer, so two ~2GiB slices would wrap the sum to zero and select
    the preallocated `SPI_BUFSIZ` buffer, which then overflows on the
    copy. Found by Karl Mehltretter.

The Rust abstractions for several buses are already present in the
kernel (PCI, platform, I2C, USB, serdev, ...), but the SPI driver
subsystem is still missing such abstractions. This series adds them,
along with a sample driver demonstrating their usage.

To my knowledge, nobody is currently working on Rust SPI abstractions;
if someone already has work in progress, please let me know and I will
happily drop or rebase this series.

The abstractions follow the same layout as the existing I2C and serdev
abstractions: a `Driver` trait for drivers to implement, an `Adapter`
for driver registration, and a `SpiDevice` wrapping `struct spi_device`.
This first installment provides synchronous `read`, `write` and
`write_then_read` operations; message-based transfers (`spi_message` /
`spi_transfer`) can be added on top in a follow-up series.

One deviation from the I2C abstractions: `spi_match_id()` is not
exported to modules, so device id matching by modalias uses the
exported `spi_get_device_id()` instead, falling back to the OF and ACPI
tables.

The series is based on the current mainline tree (7.4 merge window) and
has been build-tested with CONFIG_RUST=y, including the KUnit tests and
doctests for the new abstractions. I do not have access to real SPI
hardware to run-test this series, but the included sample driver can be
used for that purpose.

Signed-off-by: Shuai Liu <847807867@qq.com>

Shuai Liu (3):
  rust: helpers: add SPI helpers
  rust: spi: add SPI driver abstractions
  samples: rust: add SPI driver sample

 rust/bindings/bindings_helper.h |   1 +
 rust/helpers/helpers.c          |   1 +
 rust/helpers/spi.c              |  25 ++
 rust/kernel/Kconfig.test        |  11 +
 rust/kernel/lib.rs              |   2 +
 rust/kernel/spi.rs              | 570 ++++++++++++++++++++++++++++++++
 samples/rust/Kconfig            |  11 +
 samples/rust/Makefile           |   1 +
 samples/rust/rust_driver_spi.rs |  66 ++++
 9 files changed, 688 insertions(+)
 create mode 100644 rust/helpers/spi.c
 create mode 100644 rust/kernel/spi.rs
 create mode 100644 samples/rust/rust_driver_spi.rs

-- 
2.43.0

Re: [PATCH v6 0/3] Rust abstractions for the SPI driver subsystem

[Gary Guo]

On Tue Oct 27, 2026 at 5:42 AM GMT, Shuai Liu wrote:
> Changes since v5:
>   - validate in `write_then_read()` that the sum of the two buffer
>     lengths fits in `u32`: the C core's spi_write_then_read() sums the
>     two lengths as `unsigned int` when selecting and sizing its bounce
>     buffer, so two ~2GiB slices would wrap the sum to zero and select
>     the preallocated `SPI_BUFSIZ` buffer, which then overflows on the
>     copy. Found by Karl Mehltretter.
>
> The Rust abstractions for several buses are already present in the
> kernel (PCI, platform, I2C, USB, serdev, ...), but the SPI driver
> subsystem is still missing such abstractions. This series adds them,
> along with a sample driver demonstrating their usage.
>
> To my knowledge, nobody is currently working on Rust SPI abstractions;
> if someone already has work in progress, please let me know and I will
> happily drop or rebase this series.
>
> The abstractions follow the same layout as the existing I2C and serdev
> abstractions: a `Driver` trait for drivers to implement, an `Adapter`
> for driver registration, and a `SpiDevice` wrapping `struct spi_device`.
> This first installment provides synchronous `read`, `write` and
> `write_then_read` operations; message-based transfers (`spi_message` /
> `spi_transfer`) can be added on top in a follow-up series.
>
> One deviation from the I2C abstractions: `spi_match_id()` is not
> exported to modules, so device id matching by modalias uses the
> exported `spi_get_device_id()` instead, falling back to the OF and ACPI
> tables.
>
> The series is based on the current mainline tree (7.4 merge window) and
> has been build-tested with CONFIG_RUST=y, including the KUnit tests and
> doctests for the new abstractions. I do not have access to real SPI
> hardware to run-test this series, but the included sample driver can be
> used for that purpose.
>
> Signed-off-by: Shuai Liu <847807867@qq.com>

Your patches are not replies to the cover letter, as your email provider
rewrites the Message-ID. This break lore (and email clients).

You can try "--outlook-id-fix" (but it's not guaranteed to work if your email
provider doesn't report the reassigned Message-ID in the same way as outlook).
Alternatively, submit your patches via B4.

Best,
Gary

>
> Shuai Liu (3):
>   rust: helpers: add SPI helpers
>   rust: spi: add SPI driver abstractions
>   samples: rust: add SPI driver sample
>
>  rust/bindings/bindings_helper.h |   1 +
>  rust/helpers/helpers.c          |   1 +
>  rust/helpers/spi.c              |  25 ++
>  rust/kernel/Kconfig.test        |  11 +
>  rust/kernel/lib.rs              |   2 +
>  rust/kernel/spi.rs              | 570 ++++++++++++++++++++++++++++++++
>  samples/rust/Kconfig            |  11 +
>  samples/rust/Makefile           |   1 +
>  samples/rust/rust_driver_spi.rs |  66 ++++
>  9 files changed, 688 insertions(+)
>  create mode 100644 rust/helpers/spi.c
>  create mode 100644 rust/kernel/spi.rs
>  create mode 100644 samples/rust/rust_driver_spi.rs