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@nvidia.com>
---
 rust/kernel/io.rs | 110 ++++++++++++++++++++++++++++++----------------
 1 file changed, 73 insertions(+), 37 deletions(-)

diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs
index 4d98d431b523..090d1b11a896 100644
--- a/rust/kernel/io.rs
+++ b/rust/kernel/io.rs
@@ -124,8 +124,34 @@ pub fn maxsize(&self) -> usize {
 #[repr(transparent)]
 pub struct Mmio<const SIZE: usize = 0>(MmioRaw<SIZE>);
 
+macro_rules! call_mmio_read {
+    (infallible, $c_fn:ident, $self:ident, $type:ty, $addr:expr) => {
+        // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
+        unsafe { bindings::$c_fn($addr as *const c_void) as $type }
+    };
+
+    (fallible, $c_fn:ident, $self:ident, $type:ty, $addr:expr) => {{
+        // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
+        Ok(unsafe { bindings::$c_fn($addr as *const c_void) as $type })
+    }};
+}
+
+macro_rules! call_mmio_write {
+    (infallible, $c_fn:ident, $self:ident, $ty:ty, $addr:expr, $value:expr) => {
+        // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
+        unsafe { bindings::$c_fn($value, $addr as *mut c_void) }
+    };
+
+    (fallible, $c_fn:ident, $self:ident, $ty:ty, $addr:expr, $value:expr) => {{
+        // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
+        unsafe { bindings::$c_fn($value, $addr as *mut c_void) };
+        Ok(())
+    }};
+}
+
 macro_rules! define_read {
-    (infallible, $(#[$attr:meta])* $vis:vis $name:ident, $c_fn:ident -> $type_name:ty) => {
+    (infallible, $(#[$attr:meta])* $vis:vis $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
@@ -135,12 +161,13 @@ macro_rules! define_read {
         $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) }
+            // SAFETY: By the type invariant `addr` is a valid address for IO operations.
+            $call_macro!(infallible, $c_fn, self, $type_name, addr)
         }
     };
 
-    (fallible, $(#[$attr:meta])* $vis:vis $try_name:ident, $c_fn:ident -> $type_name:ty) => {
+    (fallible, $(#[$attr:meta])* $vis:vis $try_name:ident, $call_macro: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
@@ -149,14 +176,16 @@ macro_rules! define_read {
         $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.
-            Ok(unsafe { bindings::$c_fn(addr as *const c_void) })
+            // SAFETY: By the type invariant `addr` is a valid address for IO operations.
+            $call_macro!(fallible, $c_fn, self, $type_name, addr)
         }
     };
 }
+pub(crate) use define_read;
 
 macro_rules! define_write {
-    (infallible, $(#[$attr:meta])* $vis:vis $name:ident, $c_fn:ident <- $type_name:ty) => {
+    (infallible, $(#[$attr:meta])* $vis:vis $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
@@ -166,12 +195,12 @@ macro_rules! define_write {
         $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) }
+            $call_macro!(infallible, $c_fn, self, $type_name, addr, value);
         }
     };
 
-    (fallible, $(#[$attr:meta])* $vis:vis $try_name:ident, $c_fn:ident <- $type_name:ty) => {
+    (fallible, $(#[$attr:meta])* $vis:vis $try_name:ident, $call_macro: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
@@ -180,12 +209,11 @@ macro_rules! define_write {
         $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.
-            unsafe { bindings::$c_fn(value, addr as *mut c_void) }
-            Ok(())
+            $call_macro!(fallible, $c_fn, self, $type_name, addr, value)
         }
     };
 }
+pub(crate) use define_write;
 
 /// Checks whether an access of type `U` at the given `offset`
 /// is valid within this region.
@@ -298,23 +326,23 @@ fn maxsize(&self) -> usize {
 }
 
 impl<const SIZE: usize> IoInfallible for Mmio<SIZE> {
-    define_read!(infallible, read8, readb -> u8);
-    define_read!(infallible, read16, readw -> u16);
-    define_read!(infallible, read32, readl -> u32);
+    define_read!(infallible, read8, call_mmio_read, readb -> u8);
+    define_read!(infallible, read16, call_mmio_read, readw -> u16);
+    define_read!(infallible, read32, call_mmio_read, readl -> u32);
 
-    define_write!(infallible, write8, writeb <- u8);
-    define_write!(infallible, write16, writew <- u16);
-    define_write!(infallible, write32, writel <- u32);
+    define_write!(infallible, write8, call_mmio_write, writeb <- u8);
+    define_write!(infallible, write16, call_mmio_write, writew <- u16);
+    define_write!(infallible, write32, call_mmio_write, writel <- u32);
 }
 
 impl<const SIZE: usize> IoFallible for Mmio<SIZE> {
-    define_read!(fallible, try_read8, readb -> u8);
-    define_read!(fallible, try_read16, readw -> u16);
-    define_read!(fallible, try_read32, readl -> u32);
+    define_read!(fallible, try_read8, call_mmio_read, readb -> u8);
+    define_read!(fallible, try_read16, call_mmio_read, readw -> u16);
+    define_read!(fallible, try_read32, call_mmio_read, readl -> u32);
 
-    define_write!(fallible, try_write8, writeb <- u8);
-    define_write!(fallible, try_write16, writew <- u16);
-    define_write!(fallible, try_write32, writel <- u32);
+    define_write!(fallible, try_write8, call_mmio_write, writeb <- u8);
+    define_write!(fallible, try_write16, call_mmio_write, writew <- u16);
+    define_write!(fallible, try_write32, call_mmio_write, writel <- u32);
 }
 
 impl<const SIZE: usize> Mmio<SIZE> {
@@ -333,6 +361,7 @@ pub unsafe fn from_raw(raw: &MmioRaw<SIZE>) -> &Self {
         infallible,
         #[cfg(CONFIG_64BIT)]
         pub read64,
+        call_mmio_read,
         readq -> u64
     );
 
@@ -340,6 +369,7 @@ pub unsafe fn from_raw(raw: &MmioRaw<SIZE>) -> &Self {
         infallible,
         #[cfg(CONFIG_64BIT)]
         pub write64,
+        call_mmio_write,
         writeq <- u64
     );
 
@@ -347,6 +377,7 @@ pub unsafe fn from_raw(raw: &MmioRaw<SIZE>) -> &Self {
         fallible,
         #[cfg(CONFIG_64BIT)]
         pub try_read64,
+        call_mmio_read,
         readq -> u64
     );
 
@@ -354,46 +385,51 @@ pub unsafe fn from_raw(raw: &MmioRaw<SIZE>) -> &Self {
         fallible,
         #[cfg(CONFIG_64BIT)]
         pub try_write64,
+        call_mmio_write,
         writeq <- u64
     );
 
-    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, pub read8_relaxed, call_mmio_read, readb_relaxed -> u8);
+    define_read!(infallible, pub read16_relaxed, call_mmio_read, readw_relaxed -> u16);
+    define_read!(infallible, pub read32_relaxed, call_mmio_read, readl_relaxed -> u32);
     define_read!(
         infallible,
         #[cfg(CONFIG_64BIT)]
         pub read64_relaxed,
+        call_mmio_read,
         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, pub try_read8_relaxed, call_mmio_read, readb_relaxed -> u8);
+    define_read!(fallible, pub try_read16_relaxed, call_mmio_read, readw_relaxed -> u16);
+    define_read!(fallible, pub try_read32_relaxed, call_mmio_read, readl_relaxed -> u32);
     define_read!(
         fallible,
         #[cfg(CONFIG_64BIT)]
         pub try_read64_relaxed,
+        call_mmio_read,
         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, pub write8_relaxed, call_mmio_write, writeb_relaxed <- u8);
+    define_write!(infallible, pub write16_relaxed, call_mmio_write, writew_relaxed <- u16);
+    define_write!(infallible, pub write32_relaxed, call_mmio_write, writel_relaxed <- u32);
     define_write!(
         infallible,
         #[cfg(CONFIG_64BIT)]
         pub write64_relaxed,
+        call_mmio_write,
         writeq_relaxed <- u64
     );
 
-    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, pub try_write8_relaxed, call_mmio_write, writeb_relaxed <- u8);
+    define_write!(fallible, pub try_write16_relaxed, call_mmio_write, writew_relaxed <- u16);
+    define_write!(fallible, pub try_write32_relaxed, call_mmio_write, writel_relaxed <- u32);
     define_write!(
         fallible,
         #[cfg(CONFIG_64BIT)]
         pub try_write64_relaxed,
+        call_mmio_write,
         writeq_relaxed <- u64
     );
 }
-- 
2.51.0

On Tue Nov 11, 2025 at 5:41 AM JST, Zhi Wang wrote:
> 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@nvidia.com>
> ---
>  rust/kernel/io.rs | 110 ++++++++++++++++++++++++++++++----------------
>  1 file changed, 73 insertions(+), 37 deletions(-)
>
> diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs
> index 4d98d431b523..090d1b11a896 100644
> --- a/rust/kernel/io.rs
> +++ b/rust/kernel/io.rs
> @@ -124,8 +124,34 @@ pub fn maxsize(&self) -> usize {
>  #[repr(transparent)]
>  pub struct Mmio<const SIZE: usize = 0>(MmioRaw<SIZE>);
>  
> +macro_rules! call_mmio_read {
> +    (infallible, $c_fn:ident, $self:ident, $type:ty, $addr:expr) => {
> +        // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
> +        unsafe { bindings::$c_fn($addr as *const c_void) as $type }
> +    };
> +
> +    (fallible, $c_fn:ident, $self:ident, $type:ty, $addr:expr) => {{
> +        // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
> +        Ok(unsafe { bindings::$c_fn($addr as *const c_void) as $type })
> +    }};
> +}
> +
> +macro_rules! call_mmio_write {
> +    (infallible, $c_fn:ident, $self:ident, $ty:ty, $addr:expr, $value:expr) => {
> +        // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
> +        unsafe { bindings::$c_fn($value, $addr as *mut c_void) }
> +    };
> +
> +    (fallible, $c_fn:ident, $self:ident, $ty:ty, $addr:expr, $value:expr) => {{
> +        // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
> +        unsafe { bindings::$c_fn($value, $addr as *mut c_void) };
> +        Ok(())
> +    }};
> +}

I understand the intent from the commit message, but this is starting to
look like an intricate maze of macro expansion and it might not be as
easy for first-time readers - could you add an explanatory doccomment
for these?

> +
>  macro_rules! define_read {
> -    (infallible, $(#[$attr:meta])* $vis:vis $name:ident, $c_fn:ident -> $type_name:ty) => {
> +    (infallible, $(#[$attr:meta])* $vis:vis $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
> @@ -135,12 +161,13 @@ macro_rules! define_read {
>          $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) }
> +            // SAFETY: By the type invariant `addr` is a valid address for IO operations.
> +            $call_macro!(infallible, $c_fn, self, $type_name, addr)
>          }
>      };

To convey the fact that `$c_fn` is passed to `$call_macro`, how about
changing the syntax to something like 

  `define_read(infallible, $vis $name $call_macro($c_fn) -> $type_name`

?

On Thu, 13 Nov 2025 16:36:47 +0900
"Alexandre Courbot" <acourbot@nvidia.com> wrote:


> I understand the intent from the commit message, but this is starting
> to look like an intricate maze of macro expansion and it might not be
> as easy for first-time readers - could you add an explanatory
> doccomment for these?
> 

Sure.

> > +
> >  macro_rules! define_read {
> > -    (infallible, $(#[$attr:meta])* $vis:vis $name:ident,
> > $c_fn:ident -> $type_name:ty) => {
> > +    (infallible, $(#[$attr:meta])* $vis:vis $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 @@ -135,12 +161,13 @@
> > macro_rules! define_read { $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) }
> > +            // SAFETY: By the type invariant `addr` is a valid
> > address for IO operations.
> > +            $call_macro!(infallible, $c_fn, self, $type_name, addr)
> >          }
> >      };
> 
> To convey the fact that `$c_fn` is passed to `$call_macro`, how about
> changing the syntax to something like 
> 
>   `define_read(infallible, $vis $name $call_macro($c_fn) ->
> $type_name`
> 
> ?

Then the macros will look like:

define_read!(infallible, pub read32 call_mmio_read!(ioread32) -> u32);
define_write!(infallible, pub write32 call_mmio_write!(iowrite32) ->
u32);

The readability is indeed better - I’ll take that, thanks. :)

Z.