[PATCH RESEND v5 1/3] rust: io: add resource abstraction

Daniel Almeida
2025-01-16T13:06:06Z

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.

Signed-off-by: Daniel Almeida <daniel.almeida@collabora.com>
---
rust/bindings/bindings_helper.h | 1 +
rust/helpers/io.c | 7 +++++
rust/kernel/io.rs | 2 ++
rust/kernel/io/resource.rs | 53 +++++++++++++++++++++++++++++++++
4 files changed, 63 insertions(+)
create mode 100644 rust/kernel/io/resource.rs

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index e9fdceb568b8..f9c2eedb5b9b 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -16,6 +16,7 @@
#include <linux/file.h>
#include <linux/firmware.h>
#include <linux/fs.h>
+#include <linux/ioport.h>
#include <linux/jiffies.h>
#include <linux/jump_label.h>
#include <linux/mdio.h>
diff --git a/rust/helpers/io.c b/rust/helpers/io.c
index 4c2401ccd720..3cb47bd01942 100644
--- a/rust/helpers/io.c
+++ b/rust/helpers/io.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0

#include <linux/io.h>
+#include <linux/ioport.h>

void __iomem *rust_helper_ioremap(phys_addr_t offset, size_t size)
{
@@ -99,3 +100,9 @@ void rust_helper_writeq_relaxed(u64 value, volatile void __iomem *addr)
writeq_relaxed(value, addr);
}
#endif
+
+resource_size_t rust_helper_resource_size(struct resource *res)
+{
+ return resource_size(res);
+}
+
diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs
index d4a73e52e3ee..566d8b177e01 100644
--- a/rust/kernel/io.rs
+++ b/rust/kernel/io.rs
@@ -7,6 +7,8 @@
use crate::error::{code::EINVAL, Result};
use crate::{bindings, build_assert};

+pub mod resource;
+
/// Raw representation of an MMIO region.
///
/// By itself, the existence of an instance of this structure does not provide any guarantees that
diff --git a/rust/kernel/io/resource.rs b/rust/kernel/io/resource.rs
new file mode 100644
index 000000000000..ca92f9af613b
--- /dev/null
+++ b/rust/kernel/io/resource.rs
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Abstraction for system resources.
+//!
+//! C header: [`include/linux/ioport.h`](srctree/include/linux/ioport.h)
+
+use crate::str::CStr;
+use crate::types::Opaque;
+
+/// A resource abstraction.
+///
+/// # Invariants
+///
+/// `Resource` is a transparent wrapper around a valid `bindings::resource`.
+#[repr(transparent)]
+pub struct Resource(Opaque<bindings::resource>);
+
+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 will
+ /// 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) unsafe fn from_ptr<'a>(ptr: *mut bindings::resource) -> &'a Self {
+ // SAFETY: Self is a transparent wrapper around `Opaque<bindings::resource>`.
+ unsafe { &*ptr.cast() }
+ }
+
+ /// Returns the size of the resource.
+ pub fn size(&self) -> bindings::resource_size_t {
+ let inner = 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) -> u64 {
+ let inner = self.0.get();
+ // SAFETY: safe as per the invariants of `Resource`
+ unsafe { *inner }.start
+ }
+
+ /// Returns the name of the resource.
+ pub fn name(&self) -> &CStr {
+ let inner = self.0.get();
+ // SAFETY: safe as per the invariants of `Resource`
+ unsafe { CStr::from_char_ptr((*inner).name) }
+ }
+}
--
2.48.0