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Message-ID: <20251016210250.15932-3-zhiw@nvidia.com>
Date: Thu, 16 Oct 2025 21:02:47 +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 2/5] rust: io: factor out MMIO read/write macros
Refactor the existing MMIO accessors to use common call macros
instead of inlining the bindings calls in each `define_{read,write}!`
expansion.
This factoring separates the common offset/bounds checks from the
low-level call pattern, making it easier to add additional I/O accessor
families.
No functional change intended.
Signed-off-by: Zhi Wang <zhiw@...dia.com>
---
rust/kernel/io.rs | 72 ++++++++++++++++++++++++++++++-----------------
1 file changed, 46 insertions(+), 26 deletions(-)
diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs
index 78413dc7ffcc..78f7bbc945ad 100644
--- a/rust/kernel/io.rs
+++ b/rust/kernel/io.rs
@@ -4,6 +4,8 @@
//!
//! C header: [`include/asm-generic/io.h`](srctree/include/asm-generic/io.h)
+use kernel::error::Error;
+
use crate::error::{code::EINVAL, Result};
use crate::{bindings, build_assert, ffi::c_void};
@@ -113,8 +115,23 @@ pub fn maxsize(&self) -> usize {
#[repr(transparent)]
pub struct Mmio<const SIZE: usize = 0>(MmioRaw<SIZE>);
+macro_rules! call_mmio_read {
+ ($c_fn:ident, $self:ident, $offset:expr, $type:ty, $addr:expr) => {
+ // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
+ Ok::<$type, Error>(unsafe { bindings::$c_fn($addr as *const c_void) as $type })
+ };
+}
+
+macro_rules! call_mmio_write {
+ ($c_fn:ident, $self:ident, $offset:expr, $ty:ty, $addr:expr, $value:expr) => {
+ // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
+ Ok::<(), Error>(unsafe { bindings::$c_fn($value, $addr as *mut c_void) })
+ };
+}
+
macro_rules! define_read {
- ($(#[$attr:meta])* $name:ident, $try_name:ident, $c_fn:ident -> $type_name:ty) => {
+ ($(#[$attr:meta])* $name:ident, $try_name:ident, $call_macro: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
@@ -122,10 +139,9 @@ macro_rules! define_read {
$(#[$attr])*
#[inline]
pub fn $name(&self, offset: usize) -> $type_name {
- let addr = self.io_addr_assert::<$type_name>(offset);
+ 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) }
+ $call_macro!($c_fn, self, offset, $type_name, _addr).unwrap_or(!0)
}
/// Read IO data from a given offset.
@@ -134,16 +150,18 @@ pub fn $name(&self, offset: usize) -> $type_name {
/// out of bounds.
$(#[$attr])*
pub fn $try_name(&self, offset: usize) -> Result<$type_name> {
- let addr = self.io_addr::<$type_name>(offset)?;
+ let _addr = self.io_addr::<$type_name>(offset)?;
// SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
- Ok(unsafe { bindings::$c_fn(addr as *const c_void) })
+ $call_macro!($c_fn, self, offset, $type_name, _addr)
}
};
}
+pub(crate) use define_read;
macro_rules! define_write {
- ($(#[$attr:meta])* $name:ident, $try_name:ident, $c_fn:ident <- $type_name:ty) => {
+ ($(#[$attr:meta])* $name:ident, $try_name:ident, $call_macro: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
@@ -151,10 +169,9 @@ macro_rules! define_write {
$(#[$attr])*
#[inline]
pub fn $name(&self, value: $type_name, offset: usize) {
- let addr = self.io_addr_assert::<$type_name>(offset);
+ 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) }
+ let _ = $call_macro!($c_fn, self, offset, $type_name, _addr, value);
}
/// Write IO data from a given offset.
@@ -163,14 +180,13 @@ pub fn $name(&self, value: $type_name, offset: usize) {
/// out of bounds.
$(#[$attr])*
pub fn $try_name(&self, value: $type_name, offset: usize) -> Result {
- let addr = self.io_addr::<$type_name>(offset)?;
+ let _addr = self.io_addr::<$type_name>(offset)?;
- // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
- unsafe { bindings::$c_fn(value, addr as *mut c_void) }
- Ok(())
+ $call_macro!($c_fn, self, offset, $type_name, _addr, value)
}
};
}
+pub(crate) use define_write;
/// Represents a region of I/O space of a fixed size.
///
@@ -247,43 +263,47 @@ pub unsafe fn from_raw(raw: &MmioRaw<SIZE>) -> &Self {
unsafe { &*core::ptr::from_ref(raw).cast() }
}
- define_read!(read8, try_read8, readb -> u8);
- define_read!(read16, try_read16, readw -> u16);
- define_read!(read32, try_read32, readl -> u32);
+ define_read!(read8, try_read8, call_mmio_read, readb -> u8);
+ define_read!(read16, try_read16, call_mmio_read, readw -> u16);
+ define_read!(read32, try_read32, call_mmio_read, readl -> u32);
define_read!(
#[cfg(CONFIG_64BIT)]
read64,
try_read64,
+ call_mmio_read,
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!(read8_relaxed, try_read8_relaxed, call_mmio_read, readb_relaxed -> u8);
+ define_read!(read16_relaxed, try_read16_relaxed, call_mmio_read, readw_relaxed -> u16);
+ define_read!(read32_relaxed, try_read32_relaxed, call_mmio_read, readl_relaxed -> u32);
define_read!(
#[cfg(CONFIG_64BIT)]
read64_relaxed,
try_read64_relaxed,
+ call_mmio_read,
readq_relaxed -> u64
);
- define_write!(write8, try_write8, writeb <- u8);
- define_write!(write16, try_write16, writew <- u16);
- define_write!(write32, try_write32, writel <- u32);
+ define_write!(write8, try_write8, call_mmio_write, writeb <- u8);
+ define_write!(write16, try_write16, call_mmio_write, writew <- u16);
+ define_write!(write32, try_write32, call_mmio_write, writel <- u32);
define_write!(
#[cfg(CONFIG_64BIT)]
write64,
try_write64,
+ call_mmio_write,
writeq <- 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!(write8_relaxed, try_write8_relaxed, call_mmio_write, writeb_relaxed <- u8);
+ define_write!(write16_relaxed, try_write16_relaxed, call_mmio_write, writew_relaxed <- u16);
+ define_write!(write32_relaxed, try_write32_relaxed, call_mmio_write, writel_relaxed <- u32);
define_write!(
#[cfg(CONFIG_64BIT)]
write64_relaxed,
try_write64_relaxed,
+ call_mmio_write,
writeq_relaxed <- u64
);
}
--
2.47.3
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