From nobody Mon Oct 6 22:49:52 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 B04CE288CAC for ; Thu, 17 Jul 2025 09:08:41 +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=1752743323; cv=none; b=bEOkeE4vwUMoW9f2S1FptFJ267yRQ3i/d28BHzT6AHnmEu6pl7YoQZrq4nT756gnaRZpnUEbi3AcQZ5NvMxw5hmRXUfkERstq8H3r7mxTrs3OzpbChfDO2Qn35l+fkaY2m+oE9U2pdonW+GTh0cUsJJ/EBMDV/kf37OXyxalYRU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752743323; c=relaxed/simple; bh=0eHfiCvPuZiyjkmwrvr2UPkkByEj4STBt/lkt3aOKTM=; h=From:Date:Subject:MIME-Version:Message-Id:In-Reply-To:To:Cc: Content-Type:References; b=a9tiVE17PL+xX+CqxkbTIM0/IRmquYcgonLQcgL997sxeoxzRUobPwTggvCH2gLddK6BhojQ/ZDzQ1LCh1e14yMuE3pPH3QDkBh0TfegRZgD1LJr9n/nSVEUJ33RXzoDThozRb3oAxy/6uNmxc35xfEMn0651xRtB1npnSkAwLE= 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=Vfh4ph1y; 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="Vfh4ph1y" Received: from eucas1p2.samsung.com (unknown [182.198.249.207]) by mailout2.w1.samsung.com (KnoxPortal) with ESMTP id 20250717090832euoutp0248c150679ac901409470e5170c440f9b~S-sGfO4Nq1532015320euoutp02I for ; Thu, 17 Jul 2025 09:08:32 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout2.w1.samsung.com 20250717090832euoutp0248c150679ac901409470e5170c440f9b~S-sGfO4Nq1532015320euoutp02I DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1752743312; bh=YoMdpZl5sMxRXvIHkMoqJzDQgW+p/4naLd+FG+aZZQw=; h=From:Date:Subject:In-Reply-To:To:Cc:References:From; b=Vfh4ph1yQVw6NmWubLDMZvUQgAxSTTRQv/VI+Z/azWWrO/iY1dsQ2Ueqmfcw+wxxv Cix9v5C+x0T9dO+UWSmG5tzOH5uunrMJLWRcupwOWUscxfpLFJA8Fd3VzNV3NT/3/v uD/o5MvG+cqT1dipWY1PAtiAvji6PpqECYkmOGUI= Received: from eusmtip2.samsung.com (unknown [203.254.199.222]) by eucas1p2.samsung.com (KnoxPortal) with ESMTPA id 20250717090831eucas1p282ac3df2e2f1fc2a46e12c440abfbba1~S-sF8pz1C1865818658eucas1p2P; Thu, 17 Jul 2025 09:08:31 +0000 (GMT) Received: from AMDC4942.eu.corp.samsungelectronics.net (unknown [106.210.136.40]) by eusmtip2.samsung.com (KnoxPortal) with ESMTPA id 20250717090830eusmtip28f4c445e1a1c01012ec8bffef0611173~S-sExOL6F0443704437eusmtip2e; Thu, 17 Jul 2025 09:08:30 +0000 (GMT) From: Michal Wilczynski Date: Thu, 17 Jul 2025 11:08:24 +0200 Subject: [PATCH v12 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: <20250717-rust-next-pwm-working-fan-for-sending-v12-2-40f73defae0c@samsung.com> In-Reply-To: <20250717-rust-next-pwm-working-fan-for-sending-v12-0-40f73defae0c@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: 20250717090831eucas1p282ac3df2e2f1fc2a46e12c440abfbba1 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20250717090831eucas1p282ac3df2e2f1fc2a46e12c440abfbba1 X-EPHeader: CA X-CMS-RootMailID: 20250717090831eucas1p282ac3df2e2f1fc2a46e12c440abfbba1 References: <20250717-rust-next-pwm-working-fan-for-sending-v12-0-40f73defae0c@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 Reviewed-by: Daniel Almeida --- 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 a92290fffa163f9fe8fe3f04bf66426f9a894409..778c668066dda09f304b19e2366= e9011a6843dab 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -20070,6 +20070,14 @@ 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 d9bcd1e8413eaed1602d6686873e263767c58f5f..cfddeae0eab3523f04f361fb41c= cd1345c0c937b 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -790,4 +790,17 @@ 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 0f1b5d11598591bc62bb6439747211af164b76d6..73902d8bd87e93cb3bc3c501360= c37e29e8dde19 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -30,6 +30,7 @@ #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