lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-Id: <20250706-rust-next-pwm-working-fan-for-sending-v9-0-42b5ac2101c7@samsung.com> Date: Sun, 06 Jul 2025 13:45:11 +0200 From: Michal Wilczynski <m.wilczynski@...sung.com> To: Uwe Kleine-König <ukleinek@...nel.org>, Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>, Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, Björn Roy Baron <bjorn3_gh@...tonmail.com>, Andreas Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>, Michal Wilczynski <m.wilczynski@...sung.com>, Guo Ren <guoren@...nel.org>, Fu Wei <wefu@...hat.com>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>, Marek Szyprowski <m.szyprowski@...sung.com>, Benno Lossin <lossin@...nel.org>, Michael Turquette <mturquette@...libre.com>, Drew Fustini <fustini@...nel.org>, Benno Lossin <lossin@...nel.org>, Drew Fustini <fustini@...nel.org> Cc: linux-kernel@...r.kernel.org, linux-pwm@...r.kernel.org, rust-for-linux@...r.kernel.org, linux-riscv@...ts.infradead.org, devicetree@...r.kernel.org, Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org> Subject: [PATCH v9 0/6] Rust Abstractions for PWM subsystem with TH1520 PWM driver This patch series introduces Rust support for the T-HEAD TH1520 PWM controller and demonstrates its use for fan control on the Sipeed Lichee Pi 4A board. The primary goal of this patch series is to introduce a basic set of Rust abstractions for the Linux PWM subsystem. As a first user and practical demonstration of these abstractions, the series also provides a functional PWM driver for the T-HEAD TH1520 SoC. This allows control of its PWM channels and ultimately enables temperature controlled fan support for the Lichee Pi 4A board. This work aims to explore the use of Rust for PWM drivers and lay a foundation for potential future Rust based PWM drivers. The core of this series is a new rust/kernel/pwm.rs module that provides abstractions for writing PWM chip provider drivers in Rust. This has been significantly reworked from v1 based on extensive feedback. The key features of the new abstraction layer include: - Ownership and Lifetime Management: The pwm::Chip wrapper is managed by ARef, correctly tying its lifetime to its embedded struct device reference counter. Chip registration is handled by a pwm::Registration RAII guard, which guarantees that pwmchip_add is always paired with pwmchip_remove, preventing resource leaks. - Modern and Safe API: The PwmOps trait is now based on the modern waveform API (round_waveform_tohw, write_waveform, etc.) as recommended by the subsystem maintainer. It is generic over a driver's hardware specific data structure, moving all unsafe serialization logic into the abstraction layer and allowing drivers to be written in 100% safe Rust. - Ergonomics: The API provides safe, idiomatic wrappers for other PWM types (State, Args, Device, etc.) and uses standard kernel error handling patterns. The series is structured as follows: - Rust PWM Abstractions: The new safe abstraction layer. - TH1520 PWM Driver: A new Rust driver for the TH1520 SoC, built on top of the new abstractions. - Device Tree Bindings & Nodes: The remaining patches add the necessary DT bindings and nodes for the TH1520 PWM controller, and the PWM fan configuration for the Lichee Pi 4A board. Testing: Tested on the TH1520 SoC. The fan works correctly. The duty/period calculations are correct. Fan starts slow when the chip is not hot and gradually increases the speed when PVT reports higher temperatures. The patches are based on mainline, with some dependencies which are not merged yet - platform Io support [1]. Reference repository with all the patches together can be found on github [2]. [1] - https://lore.kernel.org/rust-for-linux/20250509-topics-tyr-platform_iomem-v8-0-e9f1725a40da@collabora.com/ [2] - https://github.com/mwilczy/linux/commits/rust-next-pwm-working-fan-for-sending-v14/ --- Changes in v9: - Encapsulated vtable setup in Chip::new(): The Chip::new() function is now generic over the PwmOps implementation. This allows it to create and assign the vtable internally, which simplifies the public API by removing the ops_vtable parameter from Registration::register(). - Fixed memory leak with a release handler: A custom release_callback is now assigned to the embedded struct device's release hook. This guarantees that driver specific data is always freed when the chip is destroyed, even if registration fails. - The PwmOpsVTable is now defined as a const associated item to ensure it has a 'static lifetime. - Combined introductory commits: The Device, Chip, and PwmOps abstractions are now introduced in a single commit. This was necessary to resolve the circular dependencies between them and present a clean, compilable unit for review. - Link to v8: https://lore.kernel.org/r/20250704-rust-next-pwm-working-fan-for-sending-v8-0-951e5482c9fd@samsung.com Changes in v8: - Dropped already accepted commit, re-based on top of linux-next - Reworked the Chip and PwmOps APIs to address the drvdata() type-safety comment. Chip is now generic, and PwmOps uses an associated type to provide compile-time guarantees. - Added a parent device sanity check to Registration::register(). - Updated drvdata() to return the idiomatic T::Borrowed<'_>. - added temporary unsafe blocks in the driver, as the current abstraction for Clk is neiter Safe nor Sync. I think eventually proper abstraction for Clk will be added as in a current state it's not very useful. - Link to v7: https://lore.kernel.org/r/20250702-rust-next-pwm-working-fan-for-sending-v7-0-67ef39ff1d29@samsung.com Changes in v7: - Made parent_device function private and moved casts to Device<Bound> there as well. - Link to v6: https://lore.kernel.org/r/20250701-rust-next-pwm-working-fan-for-sending-v6-0-2710932f6f6b@samsung.com Changes in v6: - Re-based on top of linux-next, dropped two already accepted commits. - After re-basing the IoMem dependent patchset stopped working, reworked it to use similar API like the PCI subsystem (I think it will end up the same). Re-worked the driver for it as well. - Remove the apply and get_state callbacks, and most of the State as well, as the old way of implementing drivers should not be possible in Rust. Left only enabled(), since it's useful for my driver. - Removed the public set_drvdata() method from pwm::Chip - Moved WFHWSIZE to the public include/linux/pwm.h header and renamed it to PWM_WFHWSIZE, allowing bindgen to create safe FFI bindings. - Corrected the ns_to_cycles integer calculation in the TH1520 driver to handle overflow correctly. - Updated the Kconfig entry for the TH1520 driver to select the Rust abstractions for a better user experience. - Link to v5: https://lore.kernel.org/r/20250623-rust-next-pwm-working-fan-for-sending-v5-0-0ca23747c23e@samsung.com Changes in v5: - Reworked `pwm::Chip` creation to take driver data directly, which allowed making the `chip.drvdata()` accessor infallible - added missing `pwm.c` file lost during the commit split (sorry !) - Link to v4: https://lore.kernel.org/r/20250618-rust-next-pwm-working-fan-for-sending-v4-0-a6a28f2b6d8a@samsung.com Changes in v4: - Reworked the pwm::Registration API to use the devres framework, addressing lifetime issue. - Corrected the PwmOps trait and its callbacks to use immutable references (&Chip, &Device) for improved safety. - Applied various code style and naming cleanups based on feedback - Link to v3: https://lore.kernel.org/r/20250617-rust-next-pwm-working-fan-for-sending-v3-0-1cca847c6f9f@samsung.com Changes in v3: - Addressed feedback from Uwe by making multiple changes to the TH1520 driver and the abstraction layer. - Split the core PWM abstractions into three focused commits to ease review per Benno request. - Confirmed the driver now works correctly with CONFIG_PWM_DEBUG enabled by implementing the full waveform API, which correctly reads the hardware state. - Refactored the Rust code to build cleanly with CONFIG_RUST_BUILD_ASSERT_ALLOW=n, primarily by using the try_* family of functions for IoMem access. - Included several cosmetic changes and cleanups to the abstractions per Miguel review. - Link to v2: https://lore.kernel.org/r/20250610-rust-next-pwm-working-fan-for-sending-v2-0-753e2955f110@samsung.com Changes in v2: - Reworked the PWM abstraction layer based on extensive feedback. - Replaced initial devm allocation with a proper ARef<Chip> lifetime model using AlwaysRefCounted. - Implemented a Registration RAII guard to ensure safe chip add/remove. - Migrated the PwmOps trait from the legacy .apply callback to the modern waveform API. - Refactored the TH1520 driver to use the new, safer abstractions. - Added a patch to mark essential bus clocks as CLK_IGNORE_UNUSED to fix boot hangs when the PWM and thermal sensors are enabled. - Link to v1: https://lore.kernel.org/r/20250524-rust-next-pwm-working-fan-for-sending-v1-0-bdd2d5094ff7@samsung.com --- Michal Wilczynski (6): rust: pwm: Add Kconfig and basic data structures rust: pwm: Add complete abstraction layer pwm: Add Rust driver for T-HEAD TH1520 SoC dt-bindings: pwm: thead: Add T-HEAD TH1520 PWM controller riscv: dts: thead: Add PWM controller node riscv: dts: thead: Add PWM fan and thermal control .../devicetree/bindings/pwm/thead,th1520-pwm.yaml | 48 ++ MAINTAINERS | 8 + arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts | 67 ++ arch/riscv/boot/dts/thead/th1520.dtsi | 7 + drivers/pwm/Kconfig | 24 + drivers/pwm/Makefile | 1 + drivers/pwm/pwm_th1520.rs | 352 +++++++++ rust/bindings/bindings_helper.h | 1 + rust/helpers/helpers.c | 1 + rust/helpers/pwm.c | 20 + rust/kernel/lib.rs | 2 + rust/kernel/pwm.rs | 813 +++++++++++++++++++++ 12 files changed, 1344 insertions(+) --- base-commit: 47753b5a1696283930a78aae79b29371f96f5bca change-id: 20250524-rust-next-pwm-working-fan-for-sending-552ad2d1b193 Best regards, -- Michal Wilczynski <m.wilczynski@...sung.com>
Powered by blists - more mailing lists