[PATCH 5/8] rust: io: register: allow paths for relative register bases

[Alexandre Courbot <acourbot@nvidia.com>]

Relative register bases are currently matched as `ident` fragments,
so bases declared in another module must first be imported into the
current scope.

Add `Base: Offset` and `Base: Alias` forms whose bases are matched as
`path` fragments. A colon is used because macro_rules! does not allow
a `path` fragment to be followed by `+`.

The old form continues to be accepted temporarily so in-tree users can
be converted in subsequent patches.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
 rust/kernel/io/register.rs | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/io/register.rs b/rust/kernel/io/register.rs
index 62208f52752a..4070fabb00f4 100644
--- a/rust/kernel/io/register.rs
+++ b/rust/kernel/io/register.rs
@@ -801,6 +801,26 @@ fn into_io_op(self) -> (FixedRegisterLoc<T>, T) {
 /// ```
 #[macro_export]
 macro_rules! register {
+    // Deprecated `+` syntax for relative registers and their aliases.
+    (
+        $(
+            $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty)
+                $([ $size:expr $(, stride = $stride:expr)? ])?
+                $(@ $($base:ident +)? $offset:literal)?
+                $(=> $alias:ident $(+ $alias_offset:ty)? $([$alias_idx:expr])? )?
+            { $($fields:tt)* }
+        )*
+    ) => {
+        $(
+        $crate::register!(
+            @reg $(#[$attr])* $vis $name ($storage) $([$size $(, stride = $stride)?])?
+                $(@ $($base :)? $offset)?
+                $(=> $alias $(: $alias_offset)? $([$alias_idx])? )?
+            { $($fields)* }
+        );
+        )*
+    };
+
     // Entry point for the macro, allowing multiple registers to be defined in one call.
     // It matches all possible register declaration patterns to dispatch them to corresponding
     // `@reg` rule that defines a single register.
@@ -808,8 +828,8 @@ macro_rules! register {
         $(
             $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty)
                 $([ $size:expr $(, stride = $stride:expr)? ])?
-                $(@ $($base:ident +)? $offset:literal)?
-                $(=> $alias:ident $(+ $alias_offset:path)? $([$alias_idx:expr])? )?
+                $(@ $($base:path :)? $offset:literal)?
+                $(=> $alias:path $(: $alias_offset:path)? $([$alias_idx:expr])? )?
             { $($fields:tt)* }
         )*
     ) => {

-- 
2.55.0