[PATCH v3 2/5] rust: io: factor out MMIO read/write macros

[Zhi Wang <zhiw@nvidia.com>]

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 0b48edabf39a..ded0f4ecf2ad 100644
--- a/rust/kernel/io.rs
+++ b/rust/kernel/io.rs
@@ -113,8 +113,34 @@ 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
@@ -124,12 +150,13 @@ 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
@@ -138,14 +165,16 @@ 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
@@ -155,12 +184,12 @@ 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
@@ -169,12 +198,11 @@ 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.
@@ -316,43 +344,47 @@ fn maxsize(&self) -> usize {
         self.0.maxsize()
     }
 
-    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_read!(
         infallible,
         #[cfg(CONFIG_64BIT)]
         read64,
+        call_mmio_read,
         readq -> u64
     );
 
-    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_read!(
         fallible,
         #[cfg(CONFIG_64BIT)]
         try_read64,
+        call_mmio_read,
         readq -> u64
     );
 
-    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);
     define_write!(
         infallible,
         #[cfg(CONFIG_64BIT)]
         write64,
+        call_mmio_write,
         writeq <- u64
     );
 
-    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);
     define_write!(
         fallible,
         #[cfg(CONFIG_64BIT)]
         try_write64,
+        call_mmio_write,
         writeq <- u64
     );
 }
@@ -369,43 +401,47 @@ pub unsafe fn from_raw(raw: &MmioRaw<SIZE>) -> &Self {
         unsafe { &*core::ptr::from_ref(raw).cast() }
     }
 
-    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
     );
 }
-- 
2.47.3