[PATCH v3 10/19] rust: io: remove `MmioOwned`
From: Gary Guo
Date: Mon Jun 08 2026 - 16:05:40 EST
`Io` trait is now very easy to implement. Thus, implement it on `Bar` and
`IoMem` directly and remove the `MmioOwned` struct.
Signed-off-by: Gary Guo <gary@xxxxxxxxxxx>
---
rust/kernel/devres.rs | 12 +++---
rust/kernel/io.rs | 103 +-------------------------------------------------
rust/kernel/io/mem.rs | 26 +++++++------
rust/kernel/pci/io.rs | 16 ++++----
4 files changed, 32 insertions(+), 125 deletions(-)
diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs
index aed0c994fd30..3545ffc5345d 100644
--- a/rust/kernel/devres.rs
+++ b/rust/kernel/devres.rs
@@ -68,8 +68,9 @@ struct Inner<T> {
/// devres::Devres,
/// io::{
/// Io,
-/// MmioOwned,
+/// Mmio,
/// MmioRaw,
+/// MmioBackend,
/// PhysAddr,
/// Region, //
/// },
@@ -104,12 +105,13 @@ struct Inner<T> {
/// }
/// }
///
-/// impl<const SIZE: usize> Deref for IoMem<SIZE> {
-/// type Target = MmioOwned<SIZE>;
+/// impl<'a, const SIZE: usize> Io<'a> for &'a IoMem<SIZE> {
+/// type Backend = MmioBackend;
+/// type Target = Region<SIZE>;
///
-/// fn deref(&self) -> &Self::Target {
+/// fn as_view(self) -> Mmio<'a, Region<SIZE>> {
/// // SAFETY: The memory range stored in `self` has been properly mapped in `Self::new`.
-/// unsafe { MmioOwned::from_raw(&self.0) }
+/// unsafe { Mmio::from_raw(self.0) }
/// }
/// }
/// # fn no_run(dev: &Device<Bound>) -> Result<(), Error> {
diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs
index d09d9864858d..8b3a64188b48 100644
--- a/rust/kernel/io.rs
+++ b/rust/kernel/io.rs
@@ -100,8 +100,8 @@ fn size(p: *const Self) -> usize {
/// the represented MMIO region does exist or is properly mapped.
///
/// Instead, the bus specific MMIO implementation must convert this raw representation into an
-/// `MmioOwned` instance providing the actual memory accessors. Only by the conversion into an
-/// `MmioOwned` structure any guarantees are given.
+/// `Mmio` instance providing the actual memory accessors. Only by the conversion into an `Mmio`
+/// structure any guarantees are given.
pub struct MmioRaw<T: ?Sized> {
/// Pointer is in I/O address space.
///
@@ -158,80 +158,6 @@ pub fn size(&self) -> usize {
}
}
-/// IO-mapped memory region.
-///
-/// The creator (usually a subsystem / bus such as PCI) is responsible for creating the
-/// mapping, performing an additional region request etc.
-///
-/// # Invariant
-///
-/// `addr` is the start and `maxsize` the length of valid I/O mapped memory region of size
-/// `maxsize`.
-///
-/// # Examples
-///
-/// ```no_run
-/// use kernel::{
-/// bindings,
-/// ffi::c_void,
-/// io::{
-/// Io,
-/// MmioOwned,
-/// MmioRaw,
-/// PhysAddr,
-/// Region,
-/// },
-/// };
-/// use core::ops::Deref;
-///
-/// // See also `pci::Bar` for a real example.
-/// struct IoMem<const SIZE: usize>(MmioRaw<Region<SIZE>>);
-///
-/// impl<const SIZE: usize> IoMem<SIZE> {
-/// /// # Safety
-/// ///
-/// /// [`paddr`, `paddr` + `SIZE`) must be a valid MMIO region that is mappable into the CPUs
-/// /// virtual address space.
-/// unsafe fn new(paddr: usize) -> Result<Self>{
-/// // SAFETY: By the safety requirements of this function [`paddr`, `paddr` + `SIZE`) is
-/// // valid for `ioremap`.
-/// let addr = unsafe { bindings::ioremap(paddr as PhysAddr, SIZE) };
-/// if addr.is_null() {
-/// return Err(ENOMEM);
-/// }
-///
-/// Ok(IoMem(MmioRaw::new_region(addr as usize, SIZE)?))
-/// }
-/// }
-///
-/// impl<const SIZE: usize> Drop for IoMem<SIZE> {
-/// fn drop(&mut self) {
-/// // SAFETY: `self.0.addr()` is guaranteed to be properly mapped by `Self::new`.
-/// unsafe { bindings::iounmap(self.0.addr() as *mut c_void); };
-/// }
-/// }
-///
-/// impl<const SIZE: usize> Deref for IoMem<SIZE> {
-/// type Target = MmioOwned<SIZE>;
-///
-/// fn deref(&self) -> &Self::Target {
-/// // SAFETY: The memory range stored in `self` has been properly mapped in `Self::new`.
-/// unsafe { MmioOwned::from_raw(&self.0) }
-/// }
-/// }
-///
-///# fn no_run() -> Result<(), Error> {
-/// // SAFETY: Invalid usage for example purposes.
-/// let iomem = unsafe { IoMem::<{ core::mem::size_of::<u32>() }>::new(0xBAAAAAAD)? };
-/// iomem.write32(0x42, 0x0);
-/// assert!(iomem.try_write32(0x42, 0x0).is_ok());
-/// assert!(iomem.try_write32(0x42, 0x4).is_err());
-/// # Ok(())
-/// # }
-/// ```
-#[repr(transparent)]
-pub struct MmioOwned<const SIZE: usize = 0>(MmioRaw<Region<SIZE>>);
-
/// Checks whether an access of type `U` at the given `base` and the given `offset`
/// is valid within this region.
///
@@ -947,31 +873,6 @@ fn io_write(view: <$backend as IoBackend>::View<'_, $ty>, value: $ty) {
#[cfg(CONFIG_64BIT)]
impl_mmio_io_capable!(MmioBackend, u64, readq, writeq);
-impl<'a, const SIZE: usize> Io<'a> for &'a MmioOwned<SIZE> {
- type Backend = MmioBackend;
- type Target = Region<SIZE>;
-
- #[inline]
- fn as_view(self) -> Mmio<'a, Self::Target> {
- // SAFETY: `Mmio` has same invariant as `MmioOwned`
- unsafe { Mmio::from_raw(self.0) }
- }
-}
-
-impl<const SIZE: usize> MmioOwned<SIZE> {
- /// Converts an `MmioRaw` into an `MmioOwned` 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<Region<SIZE>>) -> &Self {
- // SAFETY: `MmioOwned` is a transparent wrapper around `MmioRaw`.
- unsafe { &*core::ptr::from_ref(raw).cast() }
- }
-}
-
/// [`Mmio`] but using relaxed accessors.
///
/// This type provides an implementation of [`Io`] that uses relaxed I/O MMIO operands instead of
diff --git a/rust/kernel/io/mem.rs b/rust/kernel/io/mem.rs
index 8f6c257c5b8e..d9b3189d09b4 100644
--- a/rust/kernel/io/mem.rs
+++ b/rust/kernel/io/mem.rs
@@ -2,8 +2,6 @@
//! Generic memory-mapped IO.
-use core::ops::Deref;
-
use crate::{
device::{
Bound,
@@ -16,7 +14,9 @@
Region,
Resource, //
},
- MmioOwned,
+ Io,
+ Mmio,
+ MmioBackend,
MmioRaw, //
},
prelude::*,
@@ -210,11 +210,13 @@ pub fn into_devres(self) -> Result<Devres<ExclusiveIoMem<'static, SIZE>>> {
}
}
-impl<const SIZE: usize> Deref for ExclusiveIoMem<'_, SIZE> {
- type Target = MmioOwned<SIZE>;
+impl<'a, const SIZE: usize> Io<'a> for &'a ExclusiveIoMem<'_, SIZE> {
+ type Backend = MmioBackend;
+ type Target = super::Region<SIZE>;
- fn deref(&self) -> &Self::Target {
- &self.iomem
+ #[inline]
+ fn as_view(self) -> Mmio<'a, Self::Target> {
+ self.iomem.as_view()
}
}
@@ -290,11 +292,13 @@ fn drop(&mut self) {
}
}
-impl<const SIZE: usize> Deref for IoMem<'_, SIZE> {
- type Target = MmioOwned<SIZE>;
+impl<'a, const SIZE: usize> Io<'a> for &'a IoMem<'_, SIZE> {
+ type Backend = MmioBackend;
+ type Target = super::Region<SIZE>;
- fn deref(&self) -> &Self::Target {
+ #[inline]
+ fn as_view(self) -> Mmio<'a, Self::Target> {
// SAFETY: Safe as by the invariant of `IoMem`.
- unsafe { MmioOwned::from_raw(&self.io) }
+ unsafe { Mmio::from_raw(self.io) }
}
}
diff --git a/rust/kernel/pci/io.rs b/rust/kernel/pci/io.rs
index 9286b2e419f9..cd921cbba164 100644
--- a/rust/kernel/pci/io.rs
+++ b/rust/kernel/pci/io.rs
@@ -11,16 +11,14 @@
Io,
IoBackend,
IoCapable,
- MmioOwned,
+ Mmio,
+ MmioBackend,
MmioRaw,
Region, //
},
prelude::*,
ptr::KnownSize, //
};
-use core::{
- ops::Deref, //
-};
/// Represents the size of a PCI configuration space.
///
@@ -263,12 +261,14 @@ fn drop(&mut self) {
}
}
-impl<const SIZE: usize> Deref for Bar<'_, SIZE> {
- type Target = MmioOwned<SIZE>;
+impl<'a, const SIZE: usize> Io<'a> for &'a Bar<'_, SIZE> {
+ type Backend = MmioBackend;
+ type Target = crate::io::Region<SIZE>;
- fn deref(&self) -> &Self::Target {
+ #[inline]
+ fn as_view(self) -> Mmio<'a, Self::Target> {
// SAFETY: By the type invariant of `Self`, the MMIO range in `self.io` is properly mapped.
- unsafe { MmioOwned::from_raw(&self.io) }
+ unsafe { Mmio::from_raw(self.io) }
}
}
--
2.54.0