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Message-ID: <20250113121620.21598-5-me@kloenk.dev>
Date: Mon, 13 Jan 2025 13:16:19 +0100
From: Fiona Behrens <me@...enk.dev>
To: Miguel Ojeda <ojeda@...nel.org>,
Alex Gaynor <alex.gaynor@...il.com>,
Pavel Machek <pavel@....cz>,
Lee Jones <lee@...nel.org>,
Jean Delvare <jdelvare@...e.com>
Cc: Boqun Feng <boqun.feng@...il.com>,
Gary Guo <gary@...yguo.net>,
Björn Roy Baron <bjorn3_gh@...tonmail.com>,
Benno Lossin <benno.lossin@...ton.me>,
Andreas Hindborg <a.hindborg@...nel.org>,
Alice Ryhl <aliceryhl@...gle.com>,
Trevor Gross <tmgross@...ch.edu>,
Fiona Behrens <me@...enk.dev>,
Mark Pearson <mpearson-lenovo@...ebb.ca>,
Peter Koch <pkoch@...ovo.com>,
rust-for-linux@...r.kernel.org,
linux-leds@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 4/5] rust: add I/O port abstractions with resource management
This patch introduces abstractions for working with I/O port resources,
including the `Resource` and `Region` types. These abstractions facilitate
interaction with `ioport_resource`, enabling safe management of resource
reservations and memory accesses.
Additionally, helper functions such as `outb`, `outw`, and `outl` have been
provided to write values to these resources, with matching read functions
such as `inb`, `inw`, and `inl` for accessing the port memory.
Signed-off-by: Fiona Behrens <me@...enk.dev>
---
rust/helpers/helpers.c | 1 +
rust/helpers/ioport.c | 42 ++++++++++
rust/kernel/ioport.rs | 169 +++++++++++++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 2 +
4 files changed, 214 insertions(+)
create mode 100644 rust/helpers/ioport.c
create mode 100644 rust/kernel/ioport.rs
diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
index dcf827a61b52..b40aee82fa0f 100644
--- a/rust/helpers/helpers.c
+++ b/rust/helpers/helpers.c
@@ -14,6 +14,7 @@
#include "cred.c"
#include "err.c"
#include "fs.c"
+#include "ioport.c"
#include "jump_label.c"
#include "kunit.c"
#include "mutex.c"
diff --git a/rust/helpers/ioport.c b/rust/helpers/ioport.c
new file mode 100644
index 000000000000..d9c9e2093b98
--- /dev/null
+++ b/rust/helpers/ioport.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/ioport.h>
+#include <linux/io.h>
+
+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);
+}
+
+#define define_rust_helper_out(name, type) \
+ void rust_helper_##name(type value, unsigned long addr) \
+ { \
+ (name)(value, addr); \
+ }
+
+define_rust_helper_out(outb, u8);
+define_rust_helper_out(outw, u16);
+define_rust_helper_out(outl, u32);
+
+#define define_rust_helper_in(name, type) \
+ type rust_helper_##name(unsigned long addr) \
+ { \
+ return (name)(addr); \
+ }
+
+define_rust_helper_in(inb, u8);
+define_rust_helper_in(inw, u16);
+define_rust_helper_in(inl, u32);
diff --git a/rust/kernel/ioport.rs b/rust/kernel/ioport.rs
new file mode 100644
index 000000000000..9bc342cb4663
--- /dev/null
+++ b/rust/kernel/ioport.rs
@@ -0,0 +1,169 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Abstractions of routines for detecting, reserving and
+//! allocating system resources.
+//!
+//! C header: [`include/linux/ioport.h`](srctree/include/linux/ioport.h)
+
+use core::ops::Deref;
+use core::ptr;
+
+use crate::prelude::*;
+use crate::types::Opaque;
+
+/// Resource Size type.
+/// This is a type alias to `u64`
+/// depending on the config option `CONFIG_PHYS_ADDR_T_64BIT`.
+#[cfg(CONFIG_PHYS_ADDR_T_64BIT)]
+pub type ResourceSize = u64;
+
+/// Resource Size type.
+/// This is a type alias to `u32`
+/// depending on the config option `CONFIG_PHYS_ADDR_T_64BIT`.
+#[cfg(not(CONFIG_PHYS_ADDR_T_64BIT))]
+pub type ResourceSize = u32;
+
+/// Resource node.
+#[repr(transparent)]
+pub struct Resource(Opaque<bindings::resource>);
+
+impl Resource {
+ /// Convert a raw C `struct resource` pointer to a `&'a Resource`.
+ ///
+ /// # Safety
+ ///
+ /// Callers must ensure that `ptr` is valid, non-null.
+ pub unsafe fn as_ref<'a>(ptr: *mut bindings::resource) -> &'a Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ unsafe { &*ptr.cast() }
+ }
+
+ /// Return raw pointer to the resource.
+ pub fn as_raw(&self) -> *mut bindings::resource {
+ self.0.get()
+ }
+
+ /// Get name of the resource.
+ pub fn name(&self) -> &CStr {
+ // SAFETY: self.get is valid and of type `bindings::resource`
+ let name_ptr = unsafe { ptr::read(ptr::addr_of!((*self.as_raw()).name)) };
+ // SAFETY: `name_ptr` is a valid char pointer from the resource
+ unsafe { CStr::from_char_ptr(name_ptr) }
+ }
+
+ /// Get the start of the [`Resource`].
+ #[inline]
+ pub fn start(&self) -> ResourceSize {
+ // SAFETY: self.get is valid and of type `bindings::resource`
+ unsafe { ptr::read(ptr::addr_of!((*self.as_raw()).start)) }
+ }
+
+ /// Get the end of the [`Resource`].
+ #[inline]
+ pub fn end(&self) -> ResourceSize {
+ // SAFETY: self.get is valid and of type `bindings::resource`
+ unsafe { ptr::read(ptr::addr_of!((*self.as_raw()).start)) }
+ }
+
+ /// Get the length of the Resource.
+ // Empty resource (len = 0) does not make any sense.`
+ #[allow(clippy::len_without_is_empty)]
+ pub fn len(&self) -> ResourceSize {
+ self.end() - self.start() + 1
+ }
+}
+
+/// Requested region using `request_region`. This will release the region when dropped.
+///
+/// This uses port memory from the `ioport_resource` parent resource.
+pub struct Region<'name>(&'name Resource);
+
+impl<'name> Region<'name> {
+ /// Request a new muxed region from the `ioport_resource` region.
+ #[inline]
+ pub fn request_muxed(start: ResourceSize, n: ResourceSize, name: &'name CStr) -> Option<Self> {
+ // SAFETY: C ffi call. `name` is valid for lifetime of `Self`
+ unsafe { Self::from_resource(bindings::request_muxed_region(start, n, name.as_char_ptr())) }
+ }
+
+ /// Request a new region from the `ioport_resource` region.
+ #[inline]
+ pub fn request(start: ResourceSize, n: ResourceSize, name: &'name CStr) -> Option<Self> {
+ // SAFETY: C ffi call. `name` is valid for lifetime of `Self`
+ unsafe { Self::from_resource(bindings::request_region(start, n, name.as_char_ptr())) }
+ }
+
+ /// Get a resource pointer and return a resource if the pointer is non-null.
+ ///
+ /// Helper for `request` and `request_muxed`.
+ ///
+ /// # Safety
+ ///
+ /// `resource` has to be a valid or null pointer to a resource.
+ unsafe fn from_resource(resource: *mut bindings::resource) -> Option<Self> {
+ if resource.is_null() {
+ None
+ } else {
+ // SAFETY: resource is a valid resource by the function requirements and non-null.
+ Some(Self(unsafe { Resource::as_ref(resource) }))
+ }
+ }
+}
+
+macro_rules! define_out {
+ ($name:ident => $type:ty) => {
+ #[doc = concat!("Write [`", stringify!($type), "`] value into port memory region at the given offset.")]
+ pub fn $name(&self, value: $type, offset: ResourceSize) {
+ let address = self.start() + offset;
+ debug_assert!((address + (core::mem::size_of::<$type>() as ResourceSize)) <= (self.end() + 1));
+ // SAFETY: ffi call, address is in the region
+ unsafe { bindings::$name(value, address) };
+ }
+ };
+ ($($name:ident => $type:ty;)*) => {
+ $(define_out! { $name => $type })*
+ };
+}
+
+macro_rules! define_in {
+ ($name:ident => $type:ty) => {
+ #[doc = concat!("Read [`", stringify!($type), "`] value from port memory region at the given offset.")]
+ pub fn $name(&self, offset: ResourceSize) -> $type {
+ let address = self.start() + offset;
+ debug_assert!((address + (core::mem::size_of::<$type>() as ResourceSize)) <= (self.end() + 1));
+ // SAFETY: ffi call, address is in the region
+ unsafe { bindings::$name(address) }
+ }
+ };
+ ($($name:ident => $type:ty;)*) => {
+ $(define_in! { $name => $type })*
+ };
+}
+
+impl Region<'_> {
+ define_out! {
+ outb => u8;
+ outw => u16;
+ outl => u32;
+ }
+ define_in! {
+ inb => u8;
+ inw => u16;
+ inl => u32;
+ }
+}
+
+impl Drop for Region<'_> {
+ fn drop(&mut self) {
+ // SAFETY: ffi call, resource is valid.
+ unsafe { bindings::release_region(self.start(), self.len()) };
+ }
+}
+
+impl Deref for Region<'_> {
+ type Target = Resource;
+
+ fn deref(&self) -> &Self::Target {
+ self.0
+ }
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 8895a1683f82..99cd706c40e7 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -43,6 +43,8 @@
pub mod fs;
pub mod init;
pub mod ioctl;
+#[cfg(CONFIG_HAS_IOPORT)]
+pub mod ioport;
pub mod jump_label;
#[cfg(CONFIG_KUNIT)]
pub mod kunit;
--
2.47.0
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