rust: io: macro_export io_define_read!() and io_define_write!()

Currently, the define_read!() and define_write!() I/O macros are crate
public. The only user outside of the I/O module is PCI (for the
configurations space I/O backend). Consequently, when CONFIG_PCI=n this
causes a compile time warning [1].

In order to fix this, rename the macros to io_define_read!() and
io_define_write!() and use #[macro_export] to export them.

This is better than making the crate public visibility conditional, as
eventually subsystems will have their own crate.

Also, I/O backends are valid to be implemented by drivers as well. For
instance, there are devices (such as GPUs) that run firmware which
allows to program other devices only accessible through the primary
device through indirect I/O.

Since the macros are now public, also add the corresponding
documentation.

Fixes: 121d87b28e1d ("rust: io: separate generic I/O helpers from MMIO implementation")
Reported-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Closes: https://lore.kernel.org/driver-core/CANiq72khOYkt6t5zwMvSiyZvWWHMZuNCMERXu=7K=_5tT-8Pgg@mail.gmail.com/ [1]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Link: https://patch.msgid.link/20260216131534.65008-1-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

1 files changed, 12 insertions, 12 deletions

diff --git a/rust/kernel/pci/io.rs b/rust/kernel/pci/io.rs
index 6ca4cf75594c..fb6edab2aea7 100644
--- a/rust/kernel/pci/io.rs
+++ b/rust/kernel/pci/io.rs
@@ -8,8 +8,8 @@ use crate::{
     device,
     devres::Devres,
     io::{
-        define_read,
-        define_write,
+        io_define_read,
+        io_define_write,
         Io,
         IoCapable,
         IoKnownSize,
@@ -88,7 +88,7 @@ pub struct ConfigSpace<'a, S: ConfigSpaceKind = Extended> {
 /// Internal helper macros used to invoke C PCI configuration space read functions.
 ///
 /// This macro is intended to be used by higher-level PCI configuration space access macros
-/// (define_read) and provides a unified expansion for infallible vs. fallible read semantics. It
+/// (io_define_read) and provides a unified expansion for infallible vs. fallible read semantics. It
 /// emits a direct call into the corresponding C helper and performs the required cast to the Rust
 /// return type.
 ///
@@ -117,9 +117,9 @@ macro_rules! call_config_read {
 /// Internal helper macros used to invoke C PCI configuration space write functions.
 ///
 /// This macro is intended to be used by higher-level PCI configuration space access macros
-/// (define_write) and provides a unified expansion for infallible vs. fallible read semantics. It
-/// emits a direct call into the corresponding C helper and performs the required cast to the Rust
-/// return type.
+/// (io_define_write) and provides a unified expansion for infallible vs. fallible read semantics.
+/// It emits a direct call into the corresponding C helper and performs the required cast to the
+/// Rust return type.
 ///
 /// # Parameters
 ///
@@ -163,13 +163,13 @@ impl<'a, S: ConfigSpaceKind> Io for ConfigSpace<'a, S> {
     // PCI configuration space does not support fallible operations.
     // The default implementations from the Io trait are not used.
 
-    define_read!(infallible, read8, call_config_read(pci_read_config_byte) -> u8);
-    define_read!(infallible, read16, call_config_read(pci_read_config_word) -> u16);
-    define_read!(infallible, read32, call_config_read(pci_read_config_dword) -> u32);
+    io_define_read!(infallible, read8, call_config_read(pci_read_config_byte) -> u8);
+    io_define_read!(infallible, read16, call_config_read(pci_read_config_word) -> u16);
+    io_define_read!(infallible, read32, call_config_read(pci_read_config_dword) -> u32);
 
-    define_write!(infallible, write8, call_config_write(pci_write_config_byte) <- u8);
-    define_write!(infallible, write16, call_config_write(pci_write_config_word) <- u16);
-    define_write!(infallible, write32, call_config_write(pci_write_config_dword) <- u32);
+    io_define_write!(infallible, write8, call_config_write(pci_write_config_byte) <- u8);
+    io_define_write!(infallible, write16, call_config_write(pci_write_config_word) <- u16);
+    io_define_write!(infallible, write32, call_config_write(pci_write_config_dword) <- u32);
 }
 
 impl<'a, S: ConfigSpaceKind> IoKnownSize for ConfigSpace<'a, S> {