From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailout2.w1.samsung.com (mailout2.w1.samsung.com [210.118.77.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BE3952E265D for ; Tue, 17 Jun 2025 14:08:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=210.118.77.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750169319; cv=none; b=rCY2F+V4I94PIhOFi1GVzCp89ZgT8qNh8zjTyme9KxUNWyrzdqiIT1Gd0p4L7qSc0u+MzmDoMtP35CipmeVYpVtLFuIhnEMjK2X2ygb8QotPC3qFsmCDyGUwxe4XRBGTAu7srH26WZTDkxc48Rx91ro7N5x2mVeqn0E55pVRafU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750169319; c=relaxed/simple; bh=wIUdELw5d+3Ec1l9wdJQcDovNkzFk6lPx+XmhyELMdY=; h=From:Subject:Date:Message-Id:MIME-Version:To:Cc:Content-Type: References; b=Y1N6SOeEP7stnDub8wSyw2yKCr5lnX2L11B3Avum0/ss4xziHIve51Dyu8NU+ee5Y0OTtgQxG/bUbCqXFObv8f3X3YrZ1y/i7JgUDfTr096wGV/W6zvSLsr78FYD8lSY7lRxCeILwu6bVuP2hr68VDOo3bld7sVReLz+/d3D90Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com; spf=pass smtp.mailfrom=samsung.com; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b=i7+cLRz4; arc=none smtp.client-ip=210.118.77.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=samsung.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b="i7+cLRz4" Received: from eucas1p1.samsung.com (unknown [182.198.249.206]) by mailout2.w1.samsung.com (KnoxPortal) with ESMTP id 20250617140835euoutp02038a5bb37599404806278de368042c9f~J2bgqU0Ik0208502085euoutp020 for ; Tue, 17 Jun 2025 14:08:35 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout2.w1.samsung.com 20250617140835euoutp02038a5bb37599404806278de368042c9f~J2bgqU0Ik0208502085euoutp020 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1750169315; bh=WwJz1SRbg41KtiY1sC2X2Jl4FNkK7CMRxy66cA1ctow=; h=From:Subject:Date:To:Cc:References:From; b=i7+cLRz4ZBYWaDqaSVC49r1Ux8zw1JU4fXQiqsfZNL+17atx59lMmTg9nWEUU+U28 Xh8zVeQZJlEZJC92ZP51vStMT479XA4VS4FwFkUEFp10ryb7cZX+T+Izv+DMG0B+g3 1f/jTAPn3+W3PZCZCMaL6UBJMeXluLMqcuXUR49M= Received: from eusmtip1.samsung.com (unknown [203.254.199.221]) by eucas1p2.samsung.com (KnoxPortal) with ESMTPA id 20250617140834eucas1p2b35624cd4903bed6d52b7cc432e6da64~J2bf7aTvf3036730367eucas1p2P; Tue, 17 Jun 2025 14:08:34 +0000 (GMT) Received: from AMDC4942.eu.corp.samsungelectronics.net (unknown [106.210.136.40]) by eusmtip1.samsung.com (KnoxPortal) with ESMTPA id 20250617140833eusmtip1eb981f749122290e9bd69bf7317df783~J2betIXdC2516525165eusmtip1A; Tue, 17 Jun 2025 14:08:33 +0000 (GMT) From: Michal Wilczynski Subject: [PATCH v3 0/9] Rust Abstractions for PWM subsystem with TH1520 PWM driver Date: Tue, 17 Jun 2025 16:07:23 +0200 Message-Id: <20250617-rust-next-pwm-working-fan-for-sending-v3-0-1cca847c6f9f@samsung.com> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAJt2UWgC/5WNsQ6DIBQAf8Uw9zWAvho79T+aDiigpBEMKNoY/ 73o0nRrx7vhbiVBeaMCuWYr8SqaYJxNkJ8y0nTCtgqMTEw45UiRF+CnMIJVywjD3MPs/NPYFrS woJ2HoKzcGZELySWrWZWT1Bq80mY5PvdH4s6E0fnXsY1st/8eIgMKtUwTpFWhdXkLog+Tbc+N6 8n+iPzTvTD6a5enbom54hWiZox+d7dtewM0AGuRNAEAAA== X-Change-ID: 20250524-rust-next-pwm-working-fan-for-sending-552ad2d1b193 To: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Michal Wilczynski , Drew Fustini , Guo Ren , Fu Wei , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Marek Szyprowski , Benno Lossin , Michael Turquette , Stephen Boyd , Benno Lossin Cc: linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-clk@vger.kernel.org, Krzysztof Kozlowski X-Mailer: b4 0.15-dev X-CMS-MailID: 20250617140834eucas1p2b35624cd4903bed6d52b7cc432e6da64 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20250617140834eucas1p2b35624cd4903bed6d52b7cc432e6da64 X-EPHeader: CA X-CMS-RootMailID: 20250617140834eucas1p2b35624cd4903bed6d52b7cc432e6da64 References: 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. - Clock Fix: A necessary fix to the TH1520 clock driver to ensure bus clocks remain enabled. - Device Tree Bindings & Nodes: The remaining patches add the necessary DT bindings and nodes for the TH1520 PWM controller, a thermal sensor, and the PWM fan configuration for the Lichee Pi 4A board. Testing: Tested on the TH1520 SoC. The fan works correctly. The duty/period calculaties 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] and math wrapper [2]. Reference repository with all the patches together can be found on github [3]. [1] - https://lore.kernel.org/rust-for-linux/20250509-topics-tyr-platform_iomem-v8-0-e9f1725a40da@collabora.com/ [2] - https://lore.kernel.org/all/20250609-math-rust-v1-v1-1-285fac00031f@samsung.com/ [3] - https://github.com/mwilczy/linux/commits/rust-next-pwm-working-fan-for-sending-v7/ --- 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 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 (9): rust: pwm: Add Kconfig and basic data structures rust: pwm: Add core 'Device' and 'Chip' object wrappers rust: pwm: Add driver operations trait and registration support pwm: Add Rust driver for T-HEAD TH1520 SoC clk: thead: Mark essential bus clocks as CLK_IGNORE_UNUSED dt-bindings: pwm: thead: Add T-HEAD TH1520 PWM controller riscv: dts: thead: Add PWM controller node riscv: dts: thead: Add PVT 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 | 18 + drivers/clk/thead/clk-th1520-ap.c | 5 +- drivers/pwm/Kconfig | 23 + drivers/pwm/Makefile | 1 + drivers/pwm/pwm_th1520.rs | 328 ++++++++ rust/bindings/bindings_helper.h | 1 + rust/helpers/helpers.c | 1 + rust/kernel/lib.rs | 2 + rust/kernel/pwm.rs | 886 +++++++++++++++++++++ 12 files changed, 1386 insertions(+), 2 deletions(-) --- base-commit: 79b01ff21368605a62b76535ab1ab5f1f726de60 change-id: 20250524-rust-next-pwm-working-fan-for-sending-552ad2d1b193 Best regards, -- Michal Wilczynski