[PATCH 1/2] rust: pci: display symbolic PCI class names

[John Hubbard <jhubbard@nvidia.com>]

The Display implementation for Class was forwarding directly to Debug
printing, resulting in raw hex values instead of PCI Class strings.

Improve things by doing a stringify!() call for each PCI Class item.
This now prints symbolic names such as "DISPLAY_VGA", instead of
"Class(0x030000)". It still falls back to Debug formatting for unknown
class values.

Suggested-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 rust/kernel/pci/id.rs | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/rust/kernel/pci/id.rs b/rust/kernel/pci/id.rs
index 8ee1dc5c3057..6e081de30faf 100644
--- a/rust/kernel/pci/id.rs
+++ b/rust/kernel/pci/id.rs
@@ -50,6 +50,17 @@ impl Class {
                 pub const $variant: Self = Self(Self::to_24bit_class($binding));
             )+
         }
+
+        impl fmt::Display for Class {
+            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                match self {
+                    $(
+                        &Self::$variant => write!(f, stringify!($variant)),
+                    )+
+                    _ => <Self as fmt::Debug>::fmt(self, f),
+                }
+            }
+        }
     };
 }
 
@@ -87,12 +98,6 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     }
 }
 
-impl fmt::Display for Class {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        <Self as fmt::Debug>::fmt(self, f)
-    }
-}
-
 impl ClassMask {
     /// Get the raw mask value.
     #[inline]
-- 
2.51.0