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 53A5B293C4B for ; Mon, 7 Jul 2025 09:49:33 +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=1751881776; cv=none; b=ROoQWNOeciO4nDWJVDeY57kYNUajKPPjnlQF0sbobpBs22nc4tM7f/J2SjDKIo+SXYVb6ljOQhKIN9C0J1AQbJybO1Luq3Y53CoKmN58MdC4HapRy78ouX/02c10eNFu19MRs1PFtDtwSWWMyMBtEKNAZoQlU2K9V9W0WY3vnwE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751881776; c=relaxed/simple; bh=AeD2hBgLfIFq8qXOrFtRk8yGOWuOGR54JxGrKux9P9w=; h=From:Date:Subject:MIME-Version:Message-Id:In-Reply-To:To:Cc: Content-Type:References; b=sQm4bSA533JCbRVpKvT1/ipNyIHw5E318DmG96V31nidDGBUqUZ2pP52qzlAb7FlDHKrAZqig5PfT5xr5w3HyBkrW/JYM07loiuoJP9eFZcK6MZUyZIl4zTsUTMrirwbdg16Fx5Z+fECInzW649fp3glLg+1nURv7g1esBNYFVc= 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=b9ITblrm; 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="b9ITblrm" Received: from eucas1p2.samsung.com (unknown [182.198.249.207]) by mailout2.w1.samsung.com (KnoxPortal) with ESMTP id 20250707094930euoutp026d8145048f0d3fb987d0ba16dcc3f68c~P7zBDOvjK1618316183euoutp02t for ; Mon, 7 Jul 2025 09:49:30 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout2.w1.samsung.com 20250707094930euoutp026d8145048f0d3fb987d0ba16dcc3f68c~P7zBDOvjK1618316183euoutp02t DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1751881770; bh=7IOdcpqFPt15Yboz3/CwL2I2Kh3Mg9UFi2hzSn3688A=; h=From:Date:Subject:In-Reply-To:To:Cc:References:From; b=b9ITblrmmjc4CfugGDmrlX0tlnzwoBVCO9KpacBOPnGrbEOsTqos3RkDeGRxfx5wk mnJdPIsRwIjvClg/hxwskM5ZogMVjc9LmlZ+qAkTVbIwJpHz1gg+Qh6qmy9PvoosqV eeth7c7ptYxtMcEG1X7+/N2LwcqMqFOPNpVcwc3Y= Received: from eusmtip1.samsung.com (unknown [203.254.199.221]) by eucas1p2.samsung.com (KnoxPortal) with ESMTPA id 20250707094929eucas1p2282257ae8e5351df04b497a6c8664ab2~P7zAJtFEs2483424834eucas1p2j; Mon, 7 Jul 2025 09:49:29 +0000 (GMT) Received: from AMDC4942.eu.corp.samsungelectronics.net (unknown [106.210.136.40]) by eusmtip1.samsung.com (KnoxPortal) with ESMTPA id 20250707094927eusmtip1f59b044b7805bd76e7bbd7aaff712720~P7y_XwZo02055920559eusmtip1L; Mon, 7 Jul 2025 09:49:27 +0000 (GMT) From: Michal Wilczynski Date: Mon, 07 Jul 2025 11:48:30 +0200 Subject: [PATCH v10 2/7] rust: pwm: Add Kconfig and basic data structures Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-Id: <20250707-rust-next-pwm-working-fan-for-sending-v10-2-d0c5cf342004@samsung.com> In-Reply-To: <20250707-rust-next-pwm-working-fan-for-sending-v10-0-d0c5cf342004@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 , 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 , Drew Fustini 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: 20250707094929eucas1p2282257ae8e5351df04b497a6c8664ab2 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20250707094929eucas1p2282257ae8e5351df04b497a6c8664ab2 X-EPHeader: CA X-CMS-RootMailID: 20250707094929eucas1p2282257ae8e5351df04b497a6c8664ab2 References: <20250707-rust-next-pwm-working-fan-for-sending-v10-0-d0c5cf342004@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 | 6 ++ 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, 180 insertions(+) diff --git a/MAINTAINERS b/MAINTAINERS index 92e9d8c7708ff4874efaa9727814ad7f1c9f6b0c..494de42ca8c36b30d80e14b03d3c9e0e054fb267 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -20196,6 +20196,12 @@ F: include/linux/pwm.h F: include/linux/pwm_backlight.h K: pwm_(config|apply_might_sleep|apply_atomic|ops) +PWM SUBSYSTEM BINDINGS [RUST] +M: Michal Wilczynski +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..c32655566d6ab9eff9d10f29e469f9aef89cecfa 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. + config RUST_PWM_ABSTRACTIONS + bool "Rust PWM abstractions support" + depends on RUST + depends on PWM=y + 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_helper.h index 5f795e60e889b9fc887013743c81b1cf92a52adb..6a6e1b1736b38f36c1dbdd875defb3b526372b67 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -66,6 +66,7 @@ #include #include #include +#include #include #include #include diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c index 1f800e78920145fc5149befb15579179dfb6e02e..c449d72fa8b19b2ab084be520466ab916c63cea7 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -35,6 +35,7 @@ #include "pid_namespace.c" #include "poll.c" #include "property.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..d75c588863685d3990b525bb1b84aa4bc35ac397 --- /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 5bbf3627212f0a26d34be0d6c160a370abf1e996..9f7038d3d501982a843d6d86571d20f1213ba9ee 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -106,6 +106,8 @@ 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..3fad101406eac728d9b12083fad7abf7b7f89b25 --- /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 = Error; + + fn try_from(polarity: bindings::pwm_polarity) -> Result { + match polarity { + bindings::pwm_polarity_PWM_POLARITY_NORMAL => Ok(Polarity::Normal), + bindings::pwm_polarity_PWM_POLARITY_INVERSED => Ok(Polarity::Inversed), + _ => Err(EINVAL), + } + } +} + +impl From for bindings::pwm_polarity { + fn from(polarity: Polarity) -> Self { + match polarity { + Polarity::Normal => bindings::pwm_polarity_PWM_POLARITY_NORMAL, + Polarity::Inversed => bindings::pwm_polarity_PWM_POLARITY_INVERSED, + } + } +} + +/// 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’s 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 pointer + /// 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` owns 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 = 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` value. + 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 + } +} -- 2.34.1