From nobody Tue Oct 7 13:27:49 2025 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 920652FCFF6 for ; Thu, 10 Jul 2025 18:54:44 +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=1752173686; cv=none; b=AMYRsax6xWuR7IK6n9cJgt0GJnrF4dSdmTUReYJpS1XevBVEwFSOtk8n2FtIOra0NhcLGj+EjuyfIFGuEgdt8l3U1o0MU6sdr0+83njnHMfwmuuaowlYGbCGDbxaH4Tn6Mpgc1VV0044UUDAQ82CbmUhpwqINXzZ4kBshlmIVaI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752173686; c=relaxed/simple; bh=/OtKJxxr+rsqjTLS7hAiA2D1ufkvpJWSTweL2w50xAQ=; h=From:Date:Subject:MIME-Version:Message-Id:In-Reply-To:To:Cc: Content-Type:References; b=EY8kbkfyZx6V1qLgu5+YhCFX9hvpEhqxlWzlOsB1t+4K+YN1wtSiLS/AblT/iYaOWf4SoXFqwwosj5fh0FNRM7KyH3txECo/IWw3cGYebvt/4zeFLqEIDQnPNR11UMdaYnln+Y39EQFz8+DnZcqF3A09MZ3wkixpT4Q77E0oqBc= 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=u2zap5jo; 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="u2zap5jo" Received: from eucas1p2.samsung.com (unknown [182.198.249.207]) by mailout2.w1.samsung.com (KnoxPortal) with ESMTP id 20250710185442euoutp029ee743dc4c72a3b9cf9a9f56da5bdb73~Q_K43TL3X0969209692euoutp02l for ; Thu, 10 Jul 2025 18:54:42 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout2.w1.samsung.com 20250710185442euoutp029ee743dc4c72a3b9cf9a9f56da5bdb73~Q_K43TL3X0969209692euoutp02l DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1752173682; bh=7z6+Dkh6UkCFrLttXWWt6W6hTmLBHMizcToymQJAPX8=; h=From:Date:Subject:In-Reply-To:To:Cc:References:From; b=u2zap5jonqHKjxqmf2NjG9JlVsL2t2ZDD/XxRtQ6h4xZOXJY3wKYzs123+YCVLY9D 8sIcZyz1cS58RaoYfQd9BkTkFOHvGa0JzbU6+APIh3JV8giRL7SbYcrIfN4xarSMvE 8fM/nxDHPSNjgR3a53kIRGvzjuxNFSgeHcrDu8nk= Received: from eusmtip1.samsung.com (unknown [203.254.199.221]) by eucas1p2.samsung.com (KnoxPortal) with ESMTPA id 20250710185440eucas1p2ea282a7bae97733fd010e69ff8003013~Q_K3U4EP83113931139eucas1p2j; Thu, 10 Jul 2025 18:54:40 +0000 (GMT) Received: from AMDC4942.eu.corp.samsungelectronics.net (unknown [106.210.136.40]) by eusmtip1.samsung.com (KnoxPortal) with ESMTPA id 20250710185439eusmtip1242ee7fd11c164ea28e3284250d5bd91~Q_K2N4Ycw2401224012eusmtip1i; Thu, 10 Jul 2025 18:54:39 +0000 (GMT) From: Michal Wilczynski Date: Thu, 10 Jul 2025 20:54:29 +0200 Subject: [PATCH v11 2/3] rust: pwm: Add Kconfig and basic data structures Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Message-Id: <20250710-rust-next-pwm-working-fan-for-sending-v11-2-93824a16f9ec@samsung.com> In-Reply-To: <20250710-rust-next-pwm-working-fan-for-sending-v11-0-93824a16f9ec@samsung.com> 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 , Drew Fustini , 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 X-Mailer: b4 0.15-dev X-CMS-MailID: 20250710185440eucas1p2ea282a7bae97733fd010e69ff8003013 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20250710185440eucas1p2ea282a7bae97733fd010e69ff8003013 X-EPHeader: CA X-CMS-RootMailID: 20250710185440eucas1p2ea282a7bae97733fd010e69ff8003013 References: <20250710-rust-next-pwm-working-fan-for-sending-v11-0-93824a16f9ec@samsung.com> Introduce the foundational support for PWM abstractions in Rust. This commit adds the `RUST_PWM_ABSTRACTIONS` Kconfig option to enable the feature, along with the necessary build-system support and C helpers. It also introduces the first set of safe wrappers for the PWM subsystem, covering the basic data carrying C structs and enums: - `Polarity`: A safe wrapper for `enum pwm_polarity`. - `Waveform`: A wrapper for `struct pwm_waveform`. - `Args`: A wrapper for `struct pwm_args`. - `State`: A wrapper for `struct pwm_state`. These types provide memory safe, idiomatic Rust representations of the core PWM data structures and form the building blocks for the abstractions that will follow. Tested-by: Drew Fustini Signed-off-by: Michal Wilczynski --- MAINTAINERS | 8 +++ drivers/pwm/Kconfig | 13 ++++ 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 | 137 ++++++++++++++++++++++++++++++++++++= ++++ 7 files changed, 182 insertions(+) diff --git a/MAINTAINERS b/MAINTAINERS index 0c1d245bf7b84f8a78b811e0c9c5a3edc09edc22..ca490a8a196c5db287045908416= 8c5483eb57b06 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -20073,6 +20073,14 @@ F: include/linux/pwm.h F: include/linux/pwm_backlight.h K: pwm_(config|apply_might_sleep|apply_atomic|ops) =20 +PWM SUBSYSTEM BINDINGS [RUST] +M: Michal Wilczynski +L: linux-pwm@vger.kernel.org +L: rust-for-linux@vger.kernel.org +S: Maintained +F: rust/helpers/pwm.c +F: rust/kernel/pwm.rs + PXA GPIO DRIVER M: Robert Jarzmik L: linux-gpio@vger.kernel.org diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index 3ef1757502ebd92b30584cd10611311a0fbfc03b..c32655566d6ab9eff9d10f29e46= 9f9aef89cecfa 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -799,4 +799,17 @@ config PWM_XILINX To compile this driver as a module, choose M here: the module will be called pwm-xilinx. =20 + config RUST_PWM_ABSTRACTIONS + bool "Rust PWM abstractions support" + depends on RUST + depends on PWM=3Dy + help + This option enables the safe Rust abstraction layer for the PWM + subsystem. It provides idiomatic wrappers and traits necessary for + writing PWM controller drivers in Rust. + + The abstractions handle resource management (like memory and reference + counting) and provide safe interfaces to the underlying C core, + allowing driver logic to be written in safe Rust. + endif diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helpe= r.h index bc494745f67b82e7a3a6f53055ece0fc3acf6e0d..e794dada5537c53f8aeae425d18= 1ec339c10f9d0 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -63,6 +63,7 @@ #include #include #include +#include #include #include #include diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c index 16fa9bca5949b85e8d4cdcfe8e6886124f72d8d8..60879e6d794ce0f87e39caafc54= 95bf5e8acf8f0 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -31,6 +31,7 @@ #include "platform.c" #include "pci.c" #include "pid_namespace.c" +#include "pwm.c" #include "rbtree.c" #include "rcu.c" #include "refcount.c" diff --git a/rust/helpers/pwm.c b/rust/helpers/pwm.c new file mode 100644 index 0000000000000000000000000000000000000000..d75c588863685d3990b525bb1b8= 4aa4bc35ac397 --- /dev/null +++ b/rust/helpers/pwm.c @@ -0,0 +1,20 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (c) 2025 Samsung Electronics Co., Ltd. +// Author: Michal Wilczynski + +#include + +struct device *rust_helper_pwmchip_parent(const struct pwm_chip *chip) +{ + return pwmchip_parent(chip); +} + +void *rust_helper_pwmchip_get_drvdata(struct pwm_chip *chip) +{ + return pwmchip_get_drvdata(chip); +} + +void rust_helper_pwmchip_set_drvdata(struct pwm_chip *chip, void *data) +{ + pwmchip_set_drvdata(chip, data); +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 6b4774b2b1c37f4da1866e993be6230bc6715841..ce1d08b14e456905dbe7b625bbb= 8ca8b08deae2a 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -105,6 +105,8 @@ pub mod seq_file; pub mod sizes; mod static_assert; +#[cfg(CONFIG_RUST_PWM_ABSTRACTIONS)] +pub mod pwm; #[doc(hidden)] pub mod std_vendor; pub mod str; diff --git a/rust/kernel/pwm.rs b/rust/kernel/pwm.rs new file mode 100644 index 0000000000000000000000000000000000000000..3fad101406eac728d9b12083fad= 7abf7b7f89b25 --- /dev/null +++ b/rust/kernel/pwm.rs @@ -0,0 +1,137 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (c) 2025 Samsung Electronics Co., Ltd. +// Author: Michal Wilczynski + +//! PWM subsystem abstractions. +//! +//! C header: [`include/linux/pwm.h`](srctree/include/linux/pwm.h). + +use crate::{ + bindings, + prelude::*, + types::Opaque, +}; +use core::convert::TryFrom; + +/// PWM polarity. Mirrors [`enum pwm_polarity`](srctree/include/linux/pwm.= h). +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +pub enum Polarity { + /// Normal polarity (duty cycle defines the high period of the signal). + Normal, + + /// Inversed polarity (duty cycle defines the low period of the signal= ). + Inversed, +} + +impl TryFrom for Polarity { + type Error =3D Error; + + fn try_from(polarity: bindings::pwm_polarity) -> Result { + match polarity { + bindings::pwm_polarity_PWM_POLARITY_NORMAL =3D> Ok(Polarity::N= ormal), + bindings::pwm_polarity_PWM_POLARITY_INVERSED =3D> Ok(Polarity:= :Inversed), + _ =3D> Err(EINVAL), + } + } +} + +impl From for bindings::pwm_polarity { + fn from(polarity: Polarity) -> Self { + match polarity { + Polarity::Normal =3D> bindings::pwm_polarity_PWM_POLARITY_NORM= AL, + Polarity::Inversed =3D> bindings::pwm_polarity_PWM_POLARITY_IN= VERSED, + } + } +} + +/// Represents a PWM waveform configuration. +/// Mirrors struct [`struct pwm_waveform`](srctree/include/linux/pwm.h). +#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)] +pub struct Waveform { + /// Total duration of one complete PWM cycle, in nanoseconds. + pub period_length_ns: u64, + + /// Duty-cycle active time, in nanoseconds. + /// + /// For a typical normal polarity configuration (active-high) this is = the + /// high time of the signal. + pub duty_length_ns: u64, + + /// Duty-cycle start offset, in nanoseconds. + /// + /// Delay from the beginning of the period to the first active edge. + /// In most simple PWM setups this is `0`, so the duty cycle starts + /// immediately at each period=E2=80=99s start. + pub duty_offset_ns: u64, +} + +impl From for Waveform { + fn from(wf: bindings::pwm_waveform) -> Self { + Waveform { + period_length_ns: wf.period_length_ns, + duty_length_ns: wf.duty_length_ns, + duty_offset_ns: wf.duty_offset_ns, + } + } +} + +impl From for bindings::pwm_waveform { + fn from(wf: Waveform) -> Self { + bindings::pwm_waveform { + period_length_ns: wf.period_length_ns, + duty_length_ns: wf.duty_length_ns, + duty_offset_ns: wf.duty_offset_ns, + } + } +} + +/// Wrapper for board-dependent PWM arguments [`struct pwm_args`](srctree/= include/linux/pwm.h). +#[repr(transparent)] +pub struct Args(Opaque); + +impl Args { + /// Creates an `Args` wrapper from a C struct pointer. + /// + /// # Safety + /// + /// The caller must ensure that `c_args_ptr` is a valid, non-null poin= ter + /// to `bindings::pwm_args` and that the pointed-to data is valid + /// for the duration of this function call (as data is copied). + unsafe fn from_c_ptr(c_args_ptr: *const bindings::pwm_args) -> Self { + // SAFETY: Caller guarantees `c_args_ptr` is valid. We dereference= it to copy. + Args(Opaque::new(unsafe { *c_args_ptr })) + } + + /// Returns the period of the PWM signal in nanoseconds. + pub fn period(&self) -> u64 { + // SAFETY: `self.0.get()` returns a pointer to the `bindings::pwm_= args` + // managed by the `Opaque` wrapper. This pointer is guaranteed to = be + // valid and aligned for the lifetime of `self` because `Opaque` o= wns a copy. + unsafe { (*self.0.get()).period } + } + + /// Returns the polarity of the PWM signal. + pub fn polarity(&self) -> Result { + // SAFETY: `self.0.get()` returns a pointer to the `bindings::pwm_= args` + // managed by the `Opaque` wrapper. This pointer is guaranteed to = be + // valid and aligned for the lifetime of `self`. + let raw_polarity =3D unsafe { (*self.0.get()).polarity }; + Polarity::try_from(raw_polarity) + } +} + +/// Wrapper for PWM state [`struct pwm_state`](srctree/include/linux/pwm.h= ). +#[repr(transparent)] +pub struct State(bindings::pwm_state); + +impl State { + /// Creates a `State` wrapper by taking ownership of a C `pwm_state` v= alue. + pub(crate) fn from_c(c_state: bindings::pwm_state) -> Self { + State(c_state) + } + + /// Returns `true` if the PWM signal is enabled. + pub fn enabled(&self) -> bool { + self.0.enabled + } +} --=20 2.34.1