From nobody Mon Oct 6 22:51:39 2025 Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) (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 F14FD2ED84D; Wed, 16 Jul 2025 21:45:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.251.105.195 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752702340; cv=none; b=evqfu7d6x3xMpMh8tnIYhzB4nus6D3zmpetYpuBjZVoiOY0xhi+cZUYNvL48t0zy5idK2mbqkSFk09mYvHrlPDMJOwUnbkNfkCxvTGbsKwnEi/LuVd4moISgN7vGeR3xwD4GZP1/r3lPmuiZI6dDEoBu1MdPZM6pHosUUtIE4/c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752702340; c=relaxed/simple; bh=NVHP2L7I+F80S0iSXz7Ayio5SqCeQC1UYDi+yY/64nc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=J6dYQz4z18W9WSd/kJYSR9ruS/VYba3GfZob6jShDFoQ9sKsdP6BYyqtyLLxZX9ehB6xUZrPRmMeCdgFhmjVbqxFaTfmyCDI6XCB3Lxw2/Uz+jUdjOWym7ed53viPLZW0jy7pOa1Jx0W3IiqVvfzjM97jU54R7NYIIjvKfl2U4o= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=Hz2DBHig; arc=none smtp.client-ip=148.251.105.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="Hz2DBHig" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1752702328; bh=NVHP2L7I+F80S0iSXz7Ayio5SqCeQC1UYDi+yY/64nc=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=Hz2DBHig2iA/huelh7HWjMNM9giutkfWS3ES2rK+8afcDcxTzmrYst9FeOBeA0nc0 JDX7NTSwiCVQM4+Y8FPXG4BWNkUmdTOlRI8txI9NqsaI/om3b7EoidfPYs3OPO9USF eg+SS5hbOiw6qIM1lZ6h1/D1DkgbP+PDr5TCYo+EDIscw9D9qr2vzu0tJ1ldHsMVbU e2/I+BXAbSAVEW7pCvZrkItyCOoiGAaREFqlOGSPM34hITfE1He3R8pi7MKmIILEQT VjEoZseZ2uNOL86okc5kjyB5W+HsTb8ufTXOjF08jdSHt3rutuXjd4iGvgL3sQo1lM bgA8ytbk/cPwQ== Received: from [192.168.0.2] (unknown [IPv6:2804:14d:72b4:82f6:67c:16ff:fe57:b5a3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: dwlsalmeida) by bali.collaboradmins.com (Postfix) with ESMTPSA id 6F24E17E10D0; Wed, 16 Jul 2025 23:45:26 +0200 (CEST) From: Daniel Almeida Date: Wed, 16 Jul 2025 18:45:13 -0300 Subject: [PATCH v14 1/3] rust: io: add resource abstraction Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250716-topics-tyr-platform_iomem-v14-1-2c2709135cb2@collabora.com> References: <20250716-topics-tyr-platform_iomem-v14-0-2c2709135cb2@collabora.com> In-Reply-To: <20250716-topics-tyr-platform_iomem-v14-0-2c2709135cb2@collabora.com> To: Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Greg Kroah-Hartman , "Rafael J. Wysocki" Cc: linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, Fiona Behrens , Daniel Almeida X-Mailer: b4 0.14.2 In preparation for ioremap support, add a Rust abstraction for struct resource. A future commit will introduce the Rust API to ioremap a resource from a platform device. The current abstraction, therefore, adds only the minimum API needed to get that done. Acked-by: Miguel Ojeda Reviewed-by: Alice Ryhl Co-developed-by: Fiona Behrens Signed-off-by: Fiona Behrens Signed-off-by: Daniel Almeida --- rust/bindings/bindings_helper.h | 1 + rust/helpers/io.c | 36 +++++++ rust/kernel/io.rs | 4 + rust/kernel/io/resource.rs | 229 ++++++++++++++++++++++++++++++++++++= ++++ 4 files changed, 270 insertions(+) diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helpe= r.h index 7e8f2285064797d5bbac5583990ff823b76c6bdc..5f795e60e889b9fc887013743c8= 1b1cf92a52adb 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -53,6 +53,7 @@ #include #include #include +#include #include #include #include diff --git a/rust/helpers/io.c b/rust/helpers/io.c index 15ea187c5466256effd07efe6f6995a1dd95a967..404776cf6717c8570c7600a2471= 2ce6e4623d3c6 100644 --- a/rust/helpers/io.c +++ b/rust/helpers/io.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 =20 #include +#include =20 void __iomem *rust_helper_ioremap(phys_addr_t offset, size_t size) { @@ -99,3 +100,38 @@ void rust_helper_writeq_relaxed(u64 value, void __iomem= *addr) writeq_relaxed(value, addr); } #endif + +resource_size_t rust_helper_resource_size(struct resource *res) +{ + return resource_size(res); +} + +struct resource *rust_helper_request_mem_region(resource_size_t start, + resource_size_t n, + const char *name) +{ + return request_mem_region(start, n, name); +} + +void rust_helper_release_mem_region(resource_size_t start, resource_size_t= n) +{ + release_mem_region(start, n); +} + +struct resource *rust_helper_request_region(resource_size_t start, + resource_size_t n, const char *name) +{ + return request_region(start, n, name); +} + +struct resource *rust_helper_request_muxed_region(resource_size_t start, + resource_size_t n, + const char *name) +{ + return request_muxed_region(start, n, name); +} + +void rust_helper_release_region(resource_size_t start, resource_size_t n) +{ + release_region(start, n); +} diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs index 72d80a6f131e3e826ecd9d2c3bcf54e89aa60cc3..7b70d5b5477e57d6d0f24bcd26b= d8b0071721bc0 100644 --- a/rust/kernel/io.rs +++ b/rust/kernel/io.rs @@ -7,6 +7,10 @@ use crate::error::{code::EINVAL, Result}; use crate::{bindings, build_assert}; =20 +pub mod resource; + +pub use resource::Resource; + /// Raw representation of an MMIO region. /// /// By itself, the existence of an instance of this structure does not pro= vide any guarantees that diff --git a/rust/kernel/io/resource.rs b/rust/kernel/io/resource.rs new file mode 100644 index 0000000000000000000000000000000000000000..ec07af06effbb00d3db186513a0= 683b491df020b --- /dev/null +++ b/rust/kernel/io/resource.rs @@ -0,0 +1,229 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Abstractions for [system +//! resources](https://docs.kernel.org/core-api/kernel-api.html#resources-= management). +//! +//! C header: [`include/linux/ioport.h`](srctree/include/linux/ioport.h) + +use core::ops::Deref; +use core::ptr::NonNull; + +use crate::prelude::*; +use crate::str::{CStr, CString}; +use crate::types::Opaque; + +/// Resource Size type. +/// +/// This is a type alias to either `u32` or `u64` depending on the config = option +/// `CONFIG_PHYS_ADDR_T_64BIT`, and it can be a u64 even on 32-bit archite= ctures. +pub type ResourceSize =3D bindings::phys_addr_t; + +/// A region allocated from a parent [`Resource`]. +/// +/// # Invariants +/// +/// - `self.0` points to a valid `bindings::resource` that was obtained th= rough +/// `bindings::__request_region`. +pub struct Region { + /// The resource returned when the region was requested. + resource: NonNull, + /// The name that was passed in when the region was requested. We need= to + /// store it for ownership reasons. + _name: CString, +} + +impl Deref for Region { + type Target =3D Resource; + + fn deref(&self) -> &Self::Target { + // SAFETY: Safe as per the invariant of `Region`. + unsafe { Resource::from_raw(self.resource.as_ptr()) } + } +} + +impl Drop for Region { + fn drop(&mut self) { + let (flags, start, size) =3D { + let res =3D &**self; + (res.flags(), res.start(), res.size()) + }; + + let release_fn =3D if flags.contains(Flags::IORESOURCE_MEM) { + bindings::release_mem_region + } else { + bindings::release_region + }; + + // SAFETY: Safe as per the invariant of `Region`. + unsafe { release_fn(start, size) }; + } +} + +// SAFETY: `Region` only holds a pointer to a C `struct resource`, which i= s safe to be used from +// any thread. +unsafe impl Send for Region {} + +// SAFETY: `Region` only holds a pointer to a C `struct resource`, referen= ces to which are +// safe to be used from any thread. +unsafe impl Sync for Region {} + +/// A resource abstraction. +/// +/// # Invariants +/// +/// [`Resource`] is a transparent wrapper around a valid `bindings::resour= ce`. +#[repr(transparent)] +pub struct Resource(Opaque); + +impl Resource { + /// Creates a reference to a [`Resource`] from a valid pointer. + /// + /// # Safety + /// + /// The caller must ensure that for the duration of 'a, the pointer wi= ll + /// point at a valid `bindings::resource`. + /// + /// The caller must also ensure that the [`Resource`] is only accessed= via the + /// returned reference for the duration of 'a. + pub(crate) const unsafe fn from_raw<'a>(ptr: *mut bindings::resource) = -> &'a Self { + // SAFETY: Self is a transparent wrapper around `Opaque`. + unsafe { &*ptr.cast() } + } + + /// Requests a resource region. + /// + /// Exclusive access will be given and the region will be marked as bu= sy. + /// Further calls to [`Self::request_region`] will return [`None`] if + /// the region, or a part of it, is already in use. + pub fn request_region( + &self, + start: ResourceSize, + size: ResourceSize, + name: CString, + flags: Flags, + ) -> Option { + // SAFETY: + // - Safe as per the invariant of `Resource`. + // - `__request_region` will store a reference to the name, but th= at is + // safe as we own it and it will not be dropped until the `Region`= is + // dropped. + let region =3D unsafe { + bindings::__request_region( + self.0.get(), + start, + size, + name.as_char_ptr(), + flags.0 as c_int, + ) + }; + + Some(Region { + resource: NonNull::new(region)?, + _name: name, + }) + } + + /// Returns the size of the resource. + pub fn size(&self) -> ResourceSize { + let inner =3D self.0.get(); + // SAFETY: safe as per the invariants of `Resource`. + unsafe { bindings::resource_size(inner) } + } + + /// Returns the start address of the resource. + pub fn start(&self) -> ResourceSize { + let inner =3D self.0.get(); + // SAFETY: safe as per the invariants of `Resource`. + unsafe { (*inner).start } + } + + /// Returns the name of the resource. + pub fn name(&self) -> Option<&CStr> { + let inner =3D self.0.get(); + + // SAFETY: safe as per the invariants of `Resource` + let name =3D unsafe { (*inner).name }; + + if name.is_null() { + return None; + } + + // SAFETY: In the C code, `resource::name` either contains a null + // pointer or points to a valid NUL-terminated C string, and at th= is + // point we know it is not null, so we can safely convert it to a + // `CStr`. + Some(unsafe { CStr::from_char_ptr(name) }) + } + + /// Returns the flags associated with the resource. + pub fn flags(&self) -> Flags { + let inner =3D self.0.get(); + // SAFETY: safe as per the invariants of `Resource` + let flags =3D unsafe { (*inner).flags }; + + Flags(flags) + } +} + +// SAFETY: `Resource` only holds a pointer to a C `struct resource`, which= is +// safe to be used from any thread. +unsafe impl Send for Resource {} + +// SAFETY: `Resource` only holds a pointer to a C `struct resource`, refer= ences +// to which are safe to be used from any thread. +unsafe impl Sync for Resource {} + +/// Resource flags as stored in the C `struct resource::flags` field. +/// +/// They can be combined with the operators `|`, `&`, and `!`. +/// +/// Values can be used from the [`flags`] module. +#[derive(Clone, Copy, PartialEq)] +pub struct Flags(c_ulong); + +impl Flags { + /// Check whether `flags` is contained in `self`. + pub fn contains(self, flags: Flags) -> bool { + (self & flags) =3D=3D flags + } +} + +impl core::ops::BitOr for Flags { + type Output =3D Self; + fn bitor(self, rhs: Self) -> Self::Output { + Self(self.0 | rhs.0) + } +} + +impl core::ops::BitAnd for Flags { + type Output =3D Self; + fn bitand(self, rhs: Self) -> Self::Output { + Self(self.0 & rhs.0) + } +} + +impl core::ops::Not for Flags { + type Output =3D Self; + fn not(self) -> Self::Output { + Self(!self.0) + } +} + +impl Flags { + /// PCI/ISA I/O ports. + pub const IORESOURCE_IO: Flags =3D Flags::new(bindings::IORESOURCE_IO); + + /// Resource is software muxed. + pub const IORESOURCE_MUXED: Flags =3D Flags::new(bindings::IORESOURCE_= MUXED); + + /// Resource represents a memory region. + pub const IORESOURCE_MEM: Flags =3D Flags::new(bindings::IORESOURCE_ME= M); + + /// Resource represents a memory region that must be ioremaped using `= ioremap_np`. + pub const IORESOURCE_MEM_NONPOSTED: Flags =3D Flags::new(bindings::IOR= ESOURCE_MEM_NONPOSTED); + + const fn new(value: u32) -> Self { + crate::build_assert!(value as u64 <=3D c_ulong::MAX as u64); + Flags(value as c_ulong) + } +} --=20 2.50.0