rust: io: add typedef for phys_addr_t

The C typedef phys_addr_t is missing an analogue in Rust, meaning that
we end up using bindings::phys_addr_t or ResourceSize as a replacement
in various places throughout the kernel. Fix that by introducing a new
typedef on the Rust side. Place it next to the existing ResourceSize
typedef since they're quite related to each other.

Cc: stable@vger.kernel.org # for v6.18 [1]
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://patch.msgid.link/20251112-resource-phys-typedefs-v2-4-538307384f82@google.com
Link: https://lore.kernel.org/all/20251112-resource-phys-typedefs-v2-0-538307384f82@google.com/ [1]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

3 files changed, 38 insertions, 9 deletions

diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs
index 10a6a1789854..e01e0d36702d 100644
--- a/rust/kernel/devres.rs
+++ b/rust/kernel/devres.rs
@@ -52,8 +52,20 @@ struct Inner<T: Send> {
 /// # Examples
 ///
 /// ```no_run
-/// # use kernel::{bindings, device::{Bound, Device}, devres::Devres, io::{Io, IoRaw}};
-/// # use core::ops::Deref;
+/// use kernel::{
+///     bindings,
+///     device::{
+///         Bound,
+///         Device,
+///     },
+///     devres::Devres,
+///     io::{
+///         Io,
+///         IoRaw,
+///         PhysAddr,
+///     },
+/// };
+/// use core::ops::Deref;
 ///
 /// // See also [`pci::Bar`] for a real example.
 /// struct IoMem<const SIZE: usize>(IoRaw<SIZE>);
@@ -66,7 +78,7 @@ struct Inner<T: Send> {
 ///     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 bindings::phys_addr_t, SIZE) };
+///         let addr = unsafe { bindings::ioremap(paddr as PhysAddr, SIZE) };
 ///         if addr.is_null() {
 ///             return Err(ENOMEM);
 ///         }
diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs
index b8d0fb27f6ae..98e8b84e68d1 100644
--- a/rust/kernel/io.rs
+++ b/rust/kernel/io.rs
@@ -15,6 +15,12 @@ pub mod resource;
 
 pub use resource::Resource;
 
+/// Physical address type.
+///
+/// This is a type alias to either `u32` or `u64` depending on the config option
+/// `CONFIG_PHYS_ADDR_T_64BIT`, and it can be a u64 even on 32-bit architectures.
+pub type PhysAddr = bindings::phys_addr_t;
+
 /// Resource Size type.
 ///
 /// This is a type alias to either `u32` or `u64` depending on the config option
@@ -70,8 +76,16 @@ impl<const SIZE: usize> IoRaw<SIZE> {
 /// # Examples
 ///
 /// ```no_run
-/// # use kernel::{bindings, ffi::c_void, io::{Io, IoRaw}};
-/// # use core::ops::Deref;
+/// use kernel::{
+///     bindings,
+///     ffi::c_void,
+///     io::{
+///         Io,
+///         IoRaw,
+///         PhysAddr,
+///     },
+/// };
+/// use core::ops::Deref;
 ///
 /// // See also [`pci::Bar`] for a real example.
 /// struct IoMem<const SIZE: usize>(IoRaw<SIZE>);
@@ -84,7 +98,7 @@ impl<const SIZE: usize> IoRaw<SIZE> {
 ///     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 bindings::phys_addr_t, SIZE) };
+///         let addr = unsafe { bindings::ioremap(paddr as PhysAddr, SIZE) };
 ///         if addr.is_null() {
 ///             return Err(ENOMEM);
 ///         }
diff --git a/rust/kernel/io/resource.rs b/rust/kernel/io/resource.rs
index eb25cf9b4c90..56cfde97ce87 100644
--- a/rust/kernel/io/resource.rs
+++ b/rust/kernel/io/resource.rs
@@ -16,7 +16,10 @@ use crate::{
     types::Opaque, //
 };
 
-pub use super::ResourceSize;
+pub use super::{
+    PhysAddr,
+    ResourceSize, //
+};
 
 /// A region allocated from a parent [`Resource`].
 ///
@@ -97,7 +100,7 @@ impl Resource {
     /// the region, or a part of it, is already in use.
     pub fn request_region(
         &self,
-        start: ResourceSize,
+        start: PhysAddr,
         size: ResourceSize,
         name: CString,
         flags: Flags,
@@ -131,7 +134,7 @@ impl Resource {
     }
 
     /// Returns the start address of the resource.
-    pub fn start(&self) -> ResourceSize {
+    pub fn start(&self) -> PhysAddr {
         let inner = self.0.get();
         // SAFETY: Safe as per the invariants of `Resource`.
         unsafe { (*inner).start }