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Message-ID: <20251030154842.450518-2-zhiw@nvidia.com>
Date: Thu, 30 Oct 2025 15:48:38 +0000
From: Zhi Wang <zhiw@...dia.com>
To: <rust-for-linux@...r.kernel.org>
CC: <dakr@...nel.org>, <bhelgaas@...gle.com>, <kwilczynski@...nel.org>,
	<ojeda@...nel.org>, <alex.gaynor@...il.com>, <boqun.feng@...il.com>,
	<gary@...yguo.net>, <bjorn3_gh@...tonmail.com>, <lossin@...nel.org>,
	<a.hindborg@...nel.org>, <aliceryhl@...gle.com>, <tmgross@...ch.edu>,
	<linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<cjia@...dia.com>, <smitra@...dia.com>, <ankita@...dia.com>,
	<aniketa@...dia.com>, <kwankhede@...dia.com>, <targupta@...dia.com>,
	<zhiw@...dia.com>, <zhiwang@...nel.org>, <acourbot@...dia.com>,
	<joelagnelf@...dia.com>, <jhubbard@...dia.com>, <markus.probst@...teo.de>,
	Bjorn Helgaas <helgaas@...nel.org>
Subject: [PATCH v3 1/5] rust: io: factor common I/O helpers into Io trait
The previous Io<SIZE> type combined both the generic I/O access helpers
and MMIO implementation details in a single struct.
To establish a cleaner layering between the I/O interface and its concrete
backends, paving the way for supporting additional I/O mechanisms in the
future, Io<SIZE> need to be factored.
Factor the common helpers into a new Io trait, and move the MMIO-specific
logic into a dedicated Mmio<SIZE> type implementing that trait. Rename the
IoRaw to MmioRaw and update the bus MMIO implementations to use MmioRaw.
No functional change intended.
Cc: Alexandre Courbot <acourbot@...dia.com>
Cc: Bjorn Helgaas <helgaas@...nel.org>
Cc: Danilo Krummrich <dakr@...nel.org>
Cc: John Hubbard <jhubbard@...dia.com>
Signed-off-by: Zhi Wang <zhiw@...dia.com>
---
 drivers/gpu/nova-core/regs/macros.rs |  90 +++++----
 drivers/gpu/nova-core/vbios.rs       |   1 +
 rust/kernel/devres.rs                |  12 +-
 rust/kernel/io.rs                    | 279 ++++++++++++++++++++-------
 rust/kernel/io/mem.rs                |  16 +-
 rust/kernel/io/poll.rs               |   4 +-
 rust/kernel/pci.rs                   |  10 +-
 samples/rust/rust_driver_pci.rs      |   2 +-
 8 files changed, 289 insertions(+), 125 deletions(-)
diff --git a/drivers/gpu/nova-core/regs/macros.rs b/drivers/gpu/nova-core/regs/macros.rs
index fd1a815fa57d..80daaa486bc1 100644
--- a/drivers/gpu/nova-core/regs/macros.rs
+++ b/drivers/gpu/nova-core/regs/macros.rs
@@ -369,16 +369,18 @@ impl $name {
 
             /// Read the register from its address in `io`.
             #[inline(always)]
-            pub(crate) fn read<const SIZE: usize, T>(io: &T) -> Self where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+            pub(crate) fn read<const SIZE: usize, T, I>(io: &T) -> Self where
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
             {
                 Self(io.read32($offset))
             }
 
             /// Write the value contained in `self` to the register address in `io`.
             #[inline(always)]
-            pub(crate) fn write<const SIZE: usize, T>(self, io: &T) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+            pub(crate) fn write<const SIZE: usize, T, I>(self, io: &T) where
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
             {
                 io.write32(self.0, $offset)
             }
@@ -386,11 +388,12 @@ pub(crate) fn write<const SIZE: usize, T>(self, io: &T) where
             /// Read the register from its address in `io` and run `f` on its value to obtain a new
             /// value to write back.
             #[inline(always)]
-            pub(crate) fn update<const SIZE: usize, T, F>(
+            pub(crate) fn update<const SIZE: usize, T, I, F>(
                 io: &T,
                 f: F,
             ) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
                 let reg = f(Self::read(io));
@@ -408,12 +411,13 @@ impl $name {
             /// Read the register from `io`, using the base address provided by `base` and adding
             /// the register's offset to it.
             #[inline(always)]
-            pub(crate) fn read<const SIZE: usize, T, B>(
+            pub(crate) fn read<const SIZE: usize, T, I, B>(
                 io: &T,
                 #[allow(unused_variables)]
                 base: &B,
             ) -> Self where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
                 B: crate::regs::macros::RegisterBase<$base>,
             {
                 const OFFSET: usize = $name::OFFSET;
@@ -428,13 +432,14 @@ pub(crate) fn read<const SIZE: usize, T, B>(
             /// Write the value contained in `self` to `io`, using the base address provided by
             /// `base` and adding the register's offset to it.
             #[inline(always)]
-            pub(crate) fn write<const SIZE: usize, T, B>(
+            pub(crate) fn write<const SIZE: usize, T, I, B>(
                 self,
                 io: &T,
                 #[allow(unused_variables)]
                 base: &B,
             ) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
                 B: crate::regs::macros::RegisterBase<$base>,
             {
                 const OFFSET: usize = $name::OFFSET;
@@ -449,12 +454,13 @@ pub(crate) fn write<const SIZE: usize, T, B>(
             /// the register's offset to it, then run `f` on its value to obtain a new value to
             /// write back.
             #[inline(always)]
-            pub(crate) fn update<const SIZE: usize, T, B, F>(
+            pub(crate) fn update<const SIZE: usize, T, I, B, F>(
                 io: &T,
                 base: &B,
                 f: F,
             ) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
                 B: crate::regs::macros::RegisterBase<$base>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
@@ -474,11 +480,12 @@ impl $name {
 
             /// Read the array register at index `idx` from its address in `io`.
             #[inline(always)]
-            pub(crate) fn read<const SIZE: usize, T>(
+            pub(crate) fn read<const SIZE: usize, T, I>(
                 io: &T,
                 idx: usize,
             ) -> Self where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
             {
                 build_assert!(idx < Self::SIZE);
 
@@ -490,12 +497,13 @@ pub(crate) fn read<const SIZE: usize, T>(
 
             /// Write the value contained in `self` to the array register with index `idx` in `io`.
             #[inline(always)]
-            pub(crate) fn write<const SIZE: usize, T>(
+            pub(crate) fn write<const SIZE: usize, T, I>(
                 self,
                 io: &T,
                 idx: usize
             ) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
             {
                 build_assert!(idx < Self::SIZE);
 
@@ -507,12 +515,13 @@ pub(crate) fn write<const SIZE: usize, T>(
             /// Read the array register at index `idx` in `io` and run `f` on its value to obtain a
             /// new value to write back.
             #[inline(always)]
-            pub(crate) fn update<const SIZE: usize, T, F>(
+            pub(crate) fn update<const SIZE: usize, T, I, F>(
                 io: &T,
                 idx: usize,
                 f: F,
             ) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
                 let reg = f(Self::read(io, idx));
@@ -524,11 +533,12 @@ pub(crate) fn update<const SIZE: usize, T, F>(
             /// The validity of `idx` is checked at run-time, and `EINVAL` is returned is the
             /// access was out-of-bounds.
             #[inline(always)]
-            pub(crate) fn try_read<const SIZE: usize, T>(
+            pub(crate) fn try_read<const SIZE: usize, T, I>(
                 io: &T,
                 idx: usize,
             ) -> ::kernel::error::Result<Self> where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
             {
                 if idx < Self::SIZE {
                     Ok(Self::read(io, idx))
@@ -542,12 +552,13 @@ pub(crate) fn try_read<const SIZE: usize, T>(
             /// The validity of `idx` is checked at run-time, and `EINVAL` is returned is the
             /// access was out-of-bounds.
             #[inline(always)]
-            pub(crate) fn try_write<const SIZE: usize, T>(
+            pub(crate) fn try_write<const SIZE: usize, T, I>(
                 self,
                 io: &T,
                 idx: usize,
             ) -> ::kernel::error::Result where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
             {
                 if idx < Self::SIZE {
                     Ok(self.write(io, idx))
@@ -562,12 +573,13 @@ pub(crate) fn try_write<const SIZE: usize, T>(
             /// The validity of `idx` is checked at run-time, and `EINVAL` is returned is the
             /// access was out-of-bounds.
             #[inline(always)]
-            pub(crate) fn try_update<const SIZE: usize, T, F>(
+            pub(crate) fn try_update<const SIZE: usize, T, I, F>(
                 io: &T,
                 idx: usize,
                 f: F,
             ) -> ::kernel::error::Result where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
                 if idx < Self::SIZE {
@@ -593,13 +605,14 @@ impl $name {
             /// Read the array register at index `idx` from `io`, using the base address provided
             /// by `base` and adding the register's offset to it.
             #[inline(always)]
-            pub(crate) fn read<const SIZE: usize, T, B>(
+            pub(crate) fn read<const SIZE: usize, T, I, B>(
                 io: &T,
                 #[allow(unused_variables)]
                 base: &B,
                 idx: usize,
             ) -> Self where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
                 B: crate::regs::macros::RegisterBase<$base>,
             {
                 build_assert!(idx < Self::SIZE);
@@ -614,14 +627,15 @@ pub(crate) fn read<const SIZE: usize, T, B>(
             /// Write the value contained in `self` to `io`, using the base address provided by
             /// `base` and adding the offset of array register `idx` to it.
             #[inline(always)]
-            pub(crate) fn write<const SIZE: usize, T, B>(
+            pub(crate) fn write<const SIZE: usize, T, I, B>(
                 self,
                 io: &T,
                 #[allow(unused_variables)]
                 base: &B,
                 idx: usize
             ) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
                 B: crate::regs::macros::RegisterBase<$base>,
             {
                 build_assert!(idx < Self::SIZE);
@@ -636,13 +650,14 @@ pub(crate) fn write<const SIZE: usize, T, B>(
             /// by `base` and adding the register's offset to it, then run `f` on its value to
             /// obtain a new value to write back.
             #[inline(always)]
-            pub(crate) fn update<const SIZE: usize, T, B, F>(
+            pub(crate) fn update<const SIZE: usize, T, I, B, F>(
                 io: &T,
                 base: &B,
                 idx: usize,
                 f: F,
             ) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
                 B: crate::regs::macros::RegisterBase<$base>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
@@ -656,12 +671,13 @@ pub(crate) fn update<const SIZE: usize, T, B, F>(
             /// The validity of `idx` is checked at run-time, and `EINVAL` is returned is the
             /// access was out-of-bounds.
             #[inline(always)]
-            pub(crate) fn try_read<const SIZE: usize, T, B>(
+            pub(crate) fn try_read<const SIZE: usize, T, I, B>(
                 io: &T,
                 base: &B,
                 idx: usize,
             ) -> ::kernel::error::Result<Self> where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
                 B: crate::regs::macros::RegisterBase<$base>,
             {
                 if idx < Self::SIZE {
@@ -677,13 +693,14 @@ pub(crate) fn try_read<const SIZE: usize, T, B>(
             /// The validity of `idx` is checked at run-time, and `EINVAL` is returned is the
             /// access was out-of-bounds.
             #[inline(always)]
-            pub(crate) fn try_write<const SIZE: usize, T, B>(
+            pub(crate) fn try_write<const SIZE: usize, T, I, B>(
                 self,
                 io: &T,
                 base: &B,
                 idx: usize,
             ) -> ::kernel::error::Result where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
                 B: crate::regs::macros::RegisterBase<$base>,
             {
                 if idx < Self::SIZE {
@@ -700,13 +717,14 @@ pub(crate) fn try_write<const SIZE: usize, T, B>(
             /// The validity of `idx` is checked at run-time, and `EINVAL` is returned is the
             /// access was out-of-bounds.
             #[inline(always)]
-            pub(crate) fn try_update<const SIZE: usize, T, B, F>(
+            pub(crate) fn try_update<const SIZE: usize, T, I, B, F>(
                 io: &T,
                 base: &B,
                 idx: usize,
                 f: F,
             ) -> ::kernel::error::Result where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = I>,
+                I: ::kernel::io::Io<SIZE>,
                 B: crate::regs::macros::RegisterBase<$base>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
diff --git a/drivers/gpu/nova-core/vbios.rs b/drivers/gpu/nova-core/vbios.rs
index 74ed6d61e6cc..cafb2d99c82b 100644
--- a/drivers/gpu/nova-core/vbios.rs
+++ b/drivers/gpu/nova-core/vbios.rs
@@ -10,6 +10,7 @@
 use kernel::error::Result;
 use kernel::prelude::*;
 use kernel::ptr::{Alignable, Alignment};
+use kernel::io::Io;
 use kernel::types::ARef;
 
 /// The offset of the VBIOS ROM in the BAR0 space.
diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs
index 10a6a1789854..12a4474df3c3 100644
--- a/rust/kernel/devres.rs
+++ b/rust/kernel/devres.rs
@@ -52,11 +52,11 @@ struct Inner<T: Send> {
 /// # Examples
 ///
 /// ```no_run
-/// # use kernel::{bindings, device::{Bound, Device}, devres::Devres, io::{Io, IoRaw}};
+/// # use kernel::{bindings, device::{Bound, Device}, devres::Devres, io::{Io, Mmio, MmioRaw}};
 /// # use core::ops::Deref;
 ///
 /// // See also [`pci::Bar`] for a real example.
-/// struct IoMem<const SIZE: usize>(IoRaw<SIZE>);
+/// struct IoMem<const SIZE: usize>(MmioRaw<SIZE>);
 ///
 /// impl<const SIZE: usize> IoMem<SIZE> {
 ///     /// # Safety
@@ -71,7 +71,7 @@ struct Inner<T: Send> {
 ///             return Err(ENOMEM);
 ///         }
 ///
-///         Ok(IoMem(IoRaw::new(addr as usize, SIZE)?))
+///         Ok(IoMem(MmioRaw::new(addr as usize, SIZE)?))
 ///     }
 /// }
 ///
@@ -83,11 +83,11 @@ struct Inner<T: Send> {
 /// }
 ///
 /// impl<const SIZE: usize> Deref for IoMem<SIZE> {
-///    type Target = Io<SIZE>;
+///    type Target = Mmio<SIZE>;
 ///
 ///    fn deref(&self) -> &Self::Target {
 ///         // SAFETY: The memory range stored in `self` has been properly mapped in `Self::new`.
-///         unsafe { Io::from_raw(&self.0) }
+///         unsafe { Mmio::from_raw(&self.0) }
 ///    }
 /// }
 /// # fn no_run(dev: &Device<Bound>) -> Result<(), Error> {
@@ -230,7 +230,7 @@ pub fn device(&self) -> &Device {
     ///
     /// ```no_run
     /// # #![cfg(CONFIG_PCI)]
-    /// # use kernel::{device::Core, devres::Devres, pci};
+    /// # use kernel::{device::Core, devres::Devres, io::Io, pci};
     ///
     /// fn from_core(dev: &pci::Device<Core>, devres: Devres<pci::Bar<0x4>>) -> Result {
     ///     let bar = devres.access(dev.as_ref())?;
diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs
index ee182b0b5452..0b48edabf39a 100644
--- a/rust/kernel/io.rs
+++ b/rust/kernel/io.rs
@@ -4,7 +4,7 @@
 //!
 //! C header: [`include/asm-generic/io.h`](srctree/include/asm-generic/io.h)
 
-use crate::error::{code::EINVAL, Result};
+use crate::error::{code::EINVAL, code::ENOTSUPP, Result};
 use crate::{bindings, build_assert, ffi::c_void};
 
 pub mod mem;
@@ -18,16 +18,16 @@
 /// By itself, the existence of an instance of this structure does not provide any guarantees that
 /// the represented MMIO region does exist or is properly mapped.
 ///
-/// Instead, the bus specific MMIO implementation must convert this raw representation into an `Io`
-/// instance providing the actual memory accessors. Only by the conversion into an `Io` structure
-/// any guarantees are given.
-pub struct IoRaw<const SIZE: usize = 0> {
+/// Instead, the bus specific MMIO implementation must convert this raw representation into an
+/// `Mmio` instance providing the actual memory accessors. Only by the conversion into an `Mmio`
+/// structure any guarantees are given.
+pub struct MmioRaw<const SIZE: usize = 0> {
     addr: usize,
     maxsize: usize,
 }
 
-impl<const SIZE: usize> IoRaw<SIZE> {
-    /// Returns a new `IoRaw` instance on success, an error otherwise.
+impl<const SIZE: usize> MmioRaw<SIZE> {
+    /// Returns a new `MmioRaw` instance on success, an error otherwise.
     pub fn new(addr: usize, maxsize: usize) -> Result<Self> {
         if maxsize < SIZE {
             return Err(EINVAL);
@@ -62,11 +62,11 @@ pub fn maxsize(&self) -> usize {
 /// # Examples
 ///
 /// ```no_run
-/// # use kernel::{bindings, ffi::c_void, io::{Io, IoRaw}};
+/// # use kernel::{bindings, ffi::c_void, io::{Io, Mmio, MmioRaw}};
 /// # use core::ops::Deref;
 ///
 /// // See also [`pci::Bar`] for a real example.
-/// struct IoMem<const SIZE: usize>(IoRaw<SIZE>);
+/// struct IoMem<const SIZE: usize>(MmioRaw<SIZE>);
 ///
 /// impl<const SIZE: usize> IoMem<SIZE> {
 ///     /// # Safety
@@ -81,7 +81,7 @@ pub fn maxsize(&self) -> usize {
 ///             return Err(ENOMEM);
 ///         }
 ///
-///         Ok(IoMem(IoRaw::new(addr as usize, SIZE)?))
+///         Ok(IoMem(MmioRaw::new(addr as usize, SIZE)?))
 ///     }
 /// }
 ///
@@ -93,11 +93,11 @@ pub fn maxsize(&self) -> usize {
 /// }
 ///
 /// impl<const SIZE: usize> Deref for IoMem<SIZE> {
-///    type Target = Io<SIZE>;
+///    type Target = Mmio<SIZE>;
 ///
 ///    fn deref(&self) -> &Self::Target {
 ///         // SAFETY: The memory range stored in `self` has been properly mapped in `Self::new`.
-///         unsafe { Io::from_raw(&self.0) }
+///         unsafe { Mmio::from_raw(&self.0) }
 ///    }
 /// }
 ///
@@ -111,29 +111,31 @@ pub fn maxsize(&self) -> usize {
 /// # }
 /// ```
 #[repr(transparent)]
-pub struct Io<const SIZE: usize = 0>(IoRaw<SIZE>);
+pub struct Mmio<const SIZE: usize = 0>(MmioRaw<SIZE>);
 
 macro_rules! define_read {
-    ($(#[$attr:meta])* $name:ident, $try_name:ident, $c_fn:ident -> $type_name:ty) => {
+    (infallible, $(#[$attr:meta])* $vis:vis $name:ident, $c_fn:ident -> $type_name:ty) => {
         /// Read IO data from a given offset known at compile time.
         ///
         /// Bound checks are performed on compile time, hence if the offset is not known at compile
         /// time, the build will fail.
         $(#[$attr])*
         #[inline]
-        pub fn $name(&self, offset: usize) -> $type_name {
+        $vis fn $name(&self, offset: usize) -> $type_name {
             let addr = self.io_addr_assert::<$type_name>(offset);
 
             // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
             unsafe { bindings::$c_fn(addr as *const c_void) }
         }
+    };
 
+    (fallible, $(#[$attr:meta])* $vis:vis $try_name:ident, $c_fn:ident -> $type_name:ty) => {
         /// Read IO data from a given offset.
         ///
         /// Bound checks are performed on runtime, it fails if the offset (plus the type size) is
         /// out of bounds.
         $(#[$attr])*
-        pub fn $try_name(&self, offset: usize) -> Result<$type_name> {
+        $vis fn $try_name(&self, offset: usize) -> Result<$type_name> {
             let addr = self.io_addr::<$type_name>(offset)?;
 
             // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
@@ -143,26 +145,28 @@ pub fn $try_name(&self, offset: usize) -> Result<$type_name> {
 }
 
 macro_rules! define_write {
-    ($(#[$attr:meta])* $name:ident, $try_name:ident, $c_fn:ident <- $type_name:ty) => {
+    (infallible, $(#[$attr:meta])* $vis:vis $name:ident, $c_fn:ident <- $type_name:ty) => {
         /// Write IO data from a given offset known at compile time.
         ///
         /// Bound checks are performed on compile time, hence if the offset is not known at compile
         /// time, the build will fail.
         $(#[$attr])*
         #[inline]
-        pub fn $name(&self, value: $type_name, offset: usize) {
+        $vis fn $name(&self, value: $type_name, offset: usize) {
             let addr = self.io_addr_assert::<$type_name>(offset);
 
             // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
             unsafe { bindings::$c_fn(value, addr as *mut c_void) }
         }
+    };
 
+    (fallible, $(#[$attr:meta])* $vis:vis $try_name:ident, $c_fn:ident <- $type_name:ty) => {
         /// Write IO data from a given offset.
         ///
         /// Bound checks are performed on runtime, it fails if the offset (plus the type size) is
         /// out of bounds.
         $(#[$attr])*
-        pub fn $try_name(&self, value: $type_name, offset: usize) -> Result {
+        $vis fn $try_name(&self, value: $type_name, offset: usize) -> Result {
             let addr = self.io_addr::<$type_name>(offset)?;
 
             // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
@@ -172,43 +176,37 @@ pub fn $try_name(&self, value: $type_name, offset: usize) -> Result {
     };
 }
 
-impl<const SIZE: usize> Io<SIZE> {
-    /// Converts an `IoRaw` into an `Io` instance, providing the accessors to the MMIO mapping.
-    ///
-    /// # Safety
-    ///
-    /// Callers must ensure that `addr` is the start of a valid I/O mapped memory region of size
-    /// `maxsize`.
-    pub unsafe fn from_raw(raw: &IoRaw<SIZE>) -> &Self {
-        // SAFETY: `Io` is a transparent wrapper around `IoRaw`.
-        unsafe { &*core::ptr::from_ref(raw).cast() }
+/// Checks whether an access of type `U` at the given `offset`
+/// is valid within this region.
+#[inline]
+const fn offset_valid<U>(offset: usize, size: usize) -> bool {
+    let type_size = core::mem::size_of::<U>();
+    if let Some(end) = offset.checked_add(type_size) {
+        end <= size && offset % type_size == 0
+    } else {
+        false
     }
+}
 
+/// Represents a region of I/O space of a fixed size.
+///
+/// Provides common helpers for offset validation and address
+/// calculation on top of a base address and maximum size.
+///
+/// Types implementing this trait (e.g. MMIO BARs or PCI config
+/// regions) can share the same accessors.
+pub trait Io<const SIZE: usize> {
     /// Returns the base address of this mapping.
-    #[inline]
-    pub fn addr(&self) -> usize {
-        self.0.addr()
-    }
+    fn addr(&self) -> usize;
 
     /// Returns the maximum size of this mapping.
-    #[inline]
-    pub fn maxsize(&self) -> usize {
-        self.0.maxsize()
-    }
-
-    #[inline]
-    const fn offset_valid<U>(offset: usize, size: usize) -> bool {
-        let type_size = core::mem::size_of::<U>();
-        if let Some(end) = offset.checked_add(type_size) {
-            end <= size && offset % type_size == 0
-        } else {
-            false
-        }
-    }
+    fn maxsize(&self) -> usize;
 
+    /// Returns the absolute I/O address for a given `offset`.
+    /// Performs runtime bounds checks using [`offset_valid`]
     #[inline]
     fn io_addr<U>(&self, offset: usize) -> Result<usize> {
-        if !Self::offset_valid::<U>(offset, self.maxsize()) {
+        if !offset_valid::<U>(offset, self.maxsize()) {
             return Err(EINVAL);
         }
 
@@ -217,50 +215,197 @@ fn io_addr<U>(&self, offset: usize) -> Result<usize> {
         self.addr().checked_add(offset).ok_or(EINVAL)
     }
 
+    /// Returns the absolute I/O address for a given `offset`,
+    /// performing compile-time bound checks.
     #[inline]
     fn io_addr_assert<U>(&self, offset: usize) -> usize {
-        build_assert!(Self::offset_valid::<U>(offset, SIZE));
+        build_assert!(offset_valid::<U>(offset, SIZE));
 
         self.addr() + offset
     }
 
-    define_read!(read8, try_read8, readb -> u8);
-    define_read!(read16, try_read16, readw -> u16);
-    define_read!(read32, try_read32, readl -> u32);
+    /// Infallible 8-bit read with compile-time bounds check.
+    fn read8(&self, _offset: usize) -> u8 {
+        !0
+    }
+
+    /// Infallible 16-bit read with compile-time bounds check.
+    fn read16(&self, _offset: usize) -> u16 {
+        !0
+    }
+
+    /// Infallible 32-bit read with compile-time bounds check.
+    fn read32(&self, _offset: usize) -> u32 {
+        !0
+    }
+
+    /// Infallible 64-bit read with compile-time bounds check (64-bit only).
+    #[cfg(CONFIG_64BIT)]
+    fn read64(&self, _offset: usize) -> u64 {
+        !0
+    }
+
+    /// Fallible 8-bit read with runtime bounds check.
+    fn try_read8(&self, _offset: usize) -> Result<u8> {
+        Err(ENOTSUPP)
+    }
+
+    /// Fallible 16-bit read with runtime bounds check.
+    fn try_read16(&self, _offset: usize) -> Result<u16> {
+        Err(ENOTSUPP)
+    }
+
+    /// Fallible 32-bit read with runtime bounds check.
+    fn try_read32(&self, _offset: usize) -> Result<u32> {
+        Err(ENOTSUPP)
+    }
+
+    /// Fallible 64-bit read with runtime bounds check (64-bit only).
+    #[cfg(CONFIG_64BIT)]
+    fn try_read64(&self, _offset: usize) -> Result<u64> {
+        Err(ENOTSUPP)
+    }
+
+    /// Infallible 8-bit write with compile-time bounds check.
+    fn write8(&self, _value: u8, _offset: usize) {
+        ()
+    }
+
+    /// Infallible 16-bit write with compile-time bounds check.
+    fn write16(&self, _value: u16, _offset: usize) {
+        ()
+    }
+
+    /// Infallible 32-bit write with compile-time bounds check.
+    fn write32(&self, _value: u32, _offset: usize) {
+        ()
+    }
+
+    /// Infallible 64-bit write with compile-time bounds check (64-bit only).
+    #[cfg(CONFIG_64BIT)]
+    fn write64(&self, _value: u64, _offset: usize) {
+        ()
+    }
+
+    /// Fallible 8-bit write with runtime bounds check.
+    fn try_write8(&self, value: u8, offset: usize) -> Result;
+
+    /// Fallible 16-bit write with runtime bounds check.
+    fn try_write16(&self, value: u16, offset: usize) -> Result;
+
+    /// Fallible 32-bit write with runtime bounds check.
+    fn try_write32(&self, value: u32, offset: usize) -> Result;
+
+    /// Fallible 64-bit write with runtime bounds check (64-bit only).
+    #[cfg(CONFIG_64BIT)]
+    fn try_write64(&self, _value: u64, _offset: usize) -> Result {
+        Err(ENOTSUPP)
+    }
+}
+
+impl<const SIZE: usize> Io<SIZE> for Mmio<SIZE> {
+    /// Returns the base address of this mapping.
+    #[inline]
+    fn addr(&self) -> usize {
+        self.0.addr()
+    }
+
+    /// Returns the maximum size of this mapping.
+    #[inline]
+    fn maxsize(&self) -> usize {
+        self.0.maxsize()
+    }
+
+    define_read!(infallible, read8, readb -> u8);
+    define_read!(infallible, read16, readw -> u16);
+    define_read!(infallible, read32, readl -> u32);
     define_read!(
+        infallible,
         #[cfg(CONFIG_64BIT)]
         read64,
-        try_read64,
         readq -> u64
     );
 
-    define_read!(read8_relaxed, try_read8_relaxed, readb_relaxed -> u8);
-    define_read!(read16_relaxed, try_read16_relaxed, readw_relaxed -> u16);
-    define_read!(read32_relaxed, try_read32_relaxed, readl_relaxed -> u32);
+    define_read!(fallible, try_read8, readb -> u8);
+    define_read!(fallible, try_read16, readw -> u16);
+    define_read!(fallible, try_read32, readl -> u32);
     define_read!(
+        fallible,
         #[cfg(CONFIG_64BIT)]
-        read64_relaxed,
-        try_read64_relaxed,
-        readq_relaxed -> u64
+        try_read64,
+        readq -> u64
     );
 
-    define_write!(write8, try_write8, writeb <- u8);
-    define_write!(write16, try_write16, writew <- u16);
-    define_write!(write32, try_write32, writel <- u32);
+    define_write!(infallible, write8, writeb <- u8);
+    define_write!(infallible, write16, writew <- u16);
+    define_write!(infallible, write32, writel <- u32);
     define_write!(
+        infallible,
         #[cfg(CONFIG_64BIT)]
         write64,
+        writeq <- u64
+    );
+
+    define_write!(fallible, try_write8, writeb <- u8);
+    define_write!(fallible, try_write16, writew <- u16);
+    define_write!(fallible, try_write32, writel <- u32);
+    define_write!(
+        fallible,
+        #[cfg(CONFIG_64BIT)]
         try_write64,
         writeq <- u64
     );
+}
+
+impl<const SIZE: usize> Mmio<SIZE> {
+    /// Converts an `MmioRaw` into an `Mmio` instance, providing the accessors to the MMIO mapping.
+    ///
+    /// # Safety
+    ///
+    /// Callers must ensure that `addr` is the start of a valid I/O mapped memory region of size
+    /// `maxsize`.
+    pub unsafe fn from_raw(raw: &MmioRaw<SIZE>) -> &Self {
+        // SAFETY: `Mmio` is a transparent wrapper around `MmioRaw`.
+        unsafe { &*core::ptr::from_ref(raw).cast() }
+    }
+
+    define_read!(infallible, pub read8_relaxed, readb_relaxed -> u8);
+    define_read!(infallible, pub read16_relaxed, readw_relaxed -> u16);
+    define_read!(infallible, pub read32_relaxed, readl_relaxed -> u32);
+    define_read!(
+        infallible,
+        #[cfg(CONFIG_64BIT)]
+        pub read64_relaxed,
+        readq_relaxed -> u64
+    );
+
+    define_read!(fallible, pub try_read8_relaxed, readb_relaxed -> u8);
+    define_read!(fallible, pub try_read16_relaxed, readw_relaxed -> u16);
+    define_read!(fallible, pub try_read32_relaxed, readl_relaxed -> u32);
+    define_read!(
+        fallible,
+        #[cfg(CONFIG_64BIT)]
+        pub try_read64_relaxed,
+        readq_relaxed -> u64
+    );
+
+    define_write!(infallible, pub write8_relaxed, writeb_relaxed <- u8);
+    define_write!(infallible, pub write16_relaxed, writew_relaxed <- u16);
+    define_write!(infallible, pub write32_relaxed, writel_relaxed <- u32);
+    define_write!(
+        infallible,
+        #[cfg(CONFIG_64BIT)]
+        pub write64_relaxed,
+        writeq_relaxed <- u64
+    );
 
-    define_write!(write8_relaxed, try_write8_relaxed, writeb_relaxed <- u8);
-    define_write!(write16_relaxed, try_write16_relaxed, writew_relaxed <- u16);
-    define_write!(write32_relaxed, try_write32_relaxed, writel_relaxed <- u32);
+    define_write!(fallible, pub try_write8_relaxed, writeb_relaxed <- u8);
+    define_write!(fallible, pub try_write16_relaxed, writew_relaxed <- u16);
+    define_write!(fallible, pub try_write32_relaxed, writel_relaxed <- u32);
     define_write!(
+        fallible,
         #[cfg(CONFIG_64BIT)]
-        write64_relaxed,
-        try_write64_relaxed,
+        pub try_write64_relaxed,
         writeq_relaxed <- u64
     );
 }
diff --git a/rust/kernel/io/mem.rs b/rust/kernel/io/mem.rs
index 6f99510bfc3a..93cad8539b18 100644
--- a/rust/kernel/io/mem.rs
+++ b/rust/kernel/io/mem.rs
@@ -11,8 +11,8 @@
 use crate::io;
 use crate::io::resource::Region;
 use crate::io::resource::Resource;
-use crate::io::Io;
-use crate::io::IoRaw;
+use crate::io::Mmio;
+use crate::io::MmioRaw;
 use crate::prelude::*;
 
 /// An IO request for a specific device and resource.
@@ -195,7 +195,7 @@ pub fn new<'a>(io_request: IoRequest<'a>) -> impl PinInit<Devres<Self>, Error> +
 }
 
 impl<const SIZE: usize> Deref for ExclusiveIoMem<SIZE> {
-    type Target = Io<SIZE>;
+    type Target = Mmio<SIZE>;
 
     fn deref(&self) -> &Self::Target {
         &self.iomem
@@ -209,10 +209,10 @@ fn deref(&self) -> &Self::Target {
 ///
 /// # Invariants
 ///
-/// [`IoMem`] always holds an [`IoRaw`] instance that holds a valid pointer to the
+/// [`IoMem`] always holds an [`MmioRaw`] instance that holds a valid pointer to the
 /// start of the I/O memory mapped region.
 pub struct IoMem<const SIZE: usize = 0> {
-    io: IoRaw<SIZE>,
+    io: MmioRaw<SIZE>,
 }
 
 impl<const SIZE: usize> IoMem<SIZE> {
@@ -247,7 +247,7 @@ fn ioremap(resource: &Resource) -> Result<Self> {
             return Err(ENOMEM);
         }
 
-        let io = IoRaw::new(addr as usize, size)?;
+        let io = MmioRaw::new(addr as usize, size)?;
         let io = IoMem { io };
 
         Ok(io)
@@ -270,10 +270,10 @@ fn drop(&mut self) {
 }
 
 impl<const SIZE: usize> Deref for IoMem<SIZE> {
-    type Target = Io<SIZE>;
+    type Target = Mmio<SIZE>;
 
     fn deref(&self) -> &Self::Target {
         // SAFETY: Safe as by the invariant of `IoMem`.
-        unsafe { Io::from_raw(&self.io) }
+        unsafe { Mmio::from_raw(&self.io) }
     }
 }
diff --git a/rust/kernel/io/poll.rs b/rust/kernel/io/poll.rs
index 613eb25047ef..a9fea091303b 100644
--- a/rust/kernel/io/poll.rs
+++ b/rust/kernel/io/poll.rs
@@ -37,12 +37,12 @@
 /// # Examples
 ///
 /// ```no_run
-/// use kernel::io::{Io, poll::read_poll_timeout};
+/// use kernel::io::{Io, Mmio, poll::read_poll_timeout};
 /// use kernel::time::Delta;
 ///
 /// const HW_READY: u16 = 0x01;
 ///
-/// fn wait_for_hardware<const SIZE: usize>(io: &Io<SIZE>) -> Result<()> {
+/// fn wait_for_hardware<const SIZE: usize>(io: &Mmio<SIZE>) -> Result<()> {
 ///     match read_poll_timeout(
 ///         // The `op` closure reads the value of a specific status register.
 ///         || io.try_read16(0x1000),
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index 7fcc5f6022c1..77a8eb39ad32 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -10,7 +10,7 @@
     devres::Devres,
     driver,
     error::{from_result, to_result, Result},
-    io::{Io, IoRaw},
+    io::{Mmio, MmioRaw},
     irq::{self, IrqRequest},
     str::CStr,
     sync::aref::ARef,
@@ -313,7 +313,7 @@ pub struct Device<Ctx: device::DeviceContext = device::Normal>(
 /// memory mapped PCI bar and its size.
 pub struct Bar<const SIZE: usize = 0> {
     pdev: ARef<Device>,
-    io: IoRaw<SIZE>,
+    io: MmioRaw<SIZE>,
     num: i32,
 }
 
@@ -349,7 +349,7 @@ fn new(pdev: &Device, num: u32, name: &CStr) -> Result<Self> {
             return Err(ENOMEM);
         }
 
-        let io = match IoRaw::new(ioptr, len as usize) {
+        let io = match MmioRaw::new(ioptr, len as usize) {
             Ok(io) => io,
             Err(err) => {
                 // SAFETY:
@@ -403,11 +403,11 @@ fn drop(&mut self) {
 }
 
 impl<const SIZE: usize> Deref for Bar<SIZE> {
-    type Target = Io<SIZE>;
+    type Target = Mmio<SIZE>;
 
     fn deref(&self) -> &Self::Target {
         // SAFETY: By the type invariant of `Self`, the MMIO range in `self.io` is properly mapped.
-        unsafe { Io::from_raw(&self.io) }
+        unsafe { Mmio::from_raw(&self.io) }
     }
 }
 
diff --git a/samples/rust/rust_driver_pci.rs b/samples/rust/rust_driver_pci.rs
index 55a683c39ed9..528e672b6b89 100644
--- a/samples/rust/rust_driver_pci.rs
+++ b/samples/rust/rust_driver_pci.rs
@@ -4,7 +4,7 @@
 //!
 //! To make this driver probe, QEMU must be run with `-device pci-testdev`.
 
-use kernel::{c_str, device::Core, devres::Devres, pci, prelude::*, sync::aref::ARef};
+use kernel::{c_str, device::Core, devres::Devres, io::Io, pci, prelude::*, sync::aref::ARef};
 
 struct Regs;
 
-- 
2.47.3
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