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Message-ID: <20251016210250.15932-2-zhiw@nvidia.com>
Date: Thu, 16 Oct 2025 21:02:46 +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>
Subject: [PATCH v2 1/5] rust/io: factor common I/O helpers into Io trait and specialize Mmio<SIZE>
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 moves the MMIO-specific
logic into a dedicated Mmio<SIZE> type implementing that trait. Rename the
IoRaw to MmioRaw and pdate the bus MMIO implementations to use MmioRaw.
No functional change intended.
Cc: Danilo Krummrich <dakr@...nel.org>
Signed-off-by: Zhi Wang <zhiw@...dia.com>
---
drivers/gpu/nova-core/regs/macros.rs | 36 +++++------
rust/kernel/io.rs | 89 +++++++++++++++++-----------
rust/kernel/io/mem.rs | 16 ++---
rust/kernel/pci.rs | 10 ++--
4 files changed, 87 insertions(+), 64 deletions(-)
diff --git a/drivers/gpu/nova-core/regs/macros.rs b/drivers/gpu/nova-core/regs/macros.rs
index 8058e1696df9..c2a6547d58cd 100644
--- a/drivers/gpu/nova-core/regs/macros.rs
+++ b/drivers/gpu/nova-core/regs/macros.rs
@@ -609,7 +609,7 @@ impl $name {
/// Read the register from its address in `io`.
#[inline(always)]
pub(crate) fn read<const SIZE: usize, T>(io: &T) -> Self where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
{
Self(io.read32($offset))
}
@@ -617,7 +617,7 @@ pub(crate) fn read<const SIZE: usize, T>(io: &T) -> Self where
/// 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>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
{
io.write32(self.0, $offset)
}
@@ -629,7 +629,7 @@ pub(crate) fn alter<const SIZE: usize, T, F>(
io: &T,
f: F,
) where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
F: ::core::ops::FnOnce(Self) -> Self,
{
let reg = f(Self::read(io));
@@ -652,7 +652,7 @@ pub(crate) fn read<const SIZE: usize, T, B>(
#[allow(unused_variables)]
base: &B,
) -> Self where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
B: crate::regs::macros::RegisterBase<$base>,
{
const OFFSET: usize = $name::OFFSET;
@@ -673,7 +673,7 @@ pub(crate) fn write<const SIZE: usize, T, B>(
#[allow(unused_variables)]
base: &B,
) where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
B: crate::regs::macros::RegisterBase<$base>,
{
const OFFSET: usize = $name::OFFSET;
@@ -693,7 +693,7 @@ pub(crate) fn alter<const SIZE: usize, T, B, F>(
base: &B,
f: F,
) where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
B: crate::regs::macros::RegisterBase<$base>,
F: ::core::ops::FnOnce(Self) -> Self,
{
@@ -717,7 +717,7 @@ pub(crate) fn read<const SIZE: usize, T>(
io: &T,
idx: usize,
) -> Self where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
{
build_assert!(idx < Self::SIZE);
@@ -734,7 +734,7 @@ pub(crate) fn write<const SIZE: usize, T>(
io: &T,
idx: usize
) where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
{
build_assert!(idx < Self::SIZE);
@@ -751,7 +751,7 @@ pub(crate) fn alter<const SIZE: usize, T, F>(
idx: usize,
f: F,
) where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
F: ::core::ops::FnOnce(Self) -> Self,
{
let reg = f(Self::read(io, idx));
@@ -767,7 +767,7 @@ pub(crate) fn try_read<const SIZE: usize, T>(
io: &T,
idx: usize,
) -> ::kernel::error::Result<Self> where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
{
if idx < Self::SIZE {
Ok(Self::read(io, idx))
@@ -786,7 +786,7 @@ pub(crate) fn try_write<const SIZE: usize, T>(
io: &T,
idx: usize,
) -> ::kernel::error::Result where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
{
if idx < Self::SIZE {
Ok(self.write(io, idx))
@@ -806,7 +806,7 @@ pub(crate) fn try_alter<const SIZE: usize, T, F>(
idx: usize,
f: F,
) -> ::kernel::error::Result where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
F: ::core::ops::FnOnce(Self) -> Self,
{
if idx < Self::SIZE {
@@ -838,7 +838,7 @@ pub(crate) fn read<const SIZE: usize, T, B>(
base: &B,
idx: usize,
) -> Self where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
B: crate::regs::macros::RegisterBase<$base>,
{
build_assert!(idx < Self::SIZE);
@@ -860,7 +860,7 @@ pub(crate) fn write<const SIZE: usize, T, B>(
base: &B,
idx: usize
) where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
B: crate::regs::macros::RegisterBase<$base>,
{
build_assert!(idx < Self::SIZE);
@@ -881,7 +881,7 @@ pub(crate) fn alter<const SIZE: usize, T, B, F>(
idx: usize,
f: F,
) where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
B: crate::regs::macros::RegisterBase<$base>,
F: ::core::ops::FnOnce(Self) -> Self,
{
@@ -900,7 +900,7 @@ pub(crate) fn try_read<const SIZE: usize, T, B>(
base: &B,
idx: usize,
) -> ::kernel::error::Result<Self> where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
B: crate::regs::macros::RegisterBase<$base>,
{
if idx < Self::SIZE {
@@ -922,7 +922,7 @@ pub(crate) fn try_write<const SIZE: usize, T, B>(
base: &B,
idx: usize,
) -> ::kernel::error::Result where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
B: crate::regs::macros::RegisterBase<$base>,
{
if idx < Self::SIZE {
@@ -945,7 +945,7 @@ pub(crate) fn try_alter<const SIZE: usize, T, B, F>(
idx: usize,
f: F,
) -> ::kernel::error::Result where
- T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ T: ::core::ops::Deref<Target = ::kernel::io::Mmio<SIZE>>,
B: crate::regs::macros::RegisterBase<$base>,
F: ::core::ops::FnOnce(Self) -> Self,
{
diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs
index ee182b0b5452..78413dc7ffcc 100644
--- a/rust/kernel/io.rs
+++ b/rust/kernel/io.rs
@@ -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::{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) }
/// }
/// }
///
@@ -111,7 +111,7 @@ 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) => {
@@ -172,32 +172,24 @@ 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() }
- }
-
+/// 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()
- }
+ fn maxsize(&self) -> usize;
+ /// 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 {
+ 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
@@ -206,6 +198,8 @@ const fn offset_valid<U>(offset: usize, size: usize) -> bool {
}
}
+ /// 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()) {
@@ -217,12 +211,41 @@ 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));
self.addr() + offset
}
+}
+
+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()
+ }
+}
+
+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!(read8, try_read8, readb -> u8);
define_read!(read16, try_read16, readw -> u16);
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/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) }
}
}
--
2.47.3
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