[PATCH] gpu: nova-core: vbios: use offset_of in PmuLookupTableHeader::new

[Rhys Lloyd <krakow20@gmail.com>]

Use the offset_of macro for each struct field, annotate the
`PmuLookupTableHeader` struct with `#[repr(C)]` attribute,
and add a TODO message to use FromBytes when available.

Signed-off-by: Rhys Lloyd <krakow20@gmail.com>
---
 drivers/gpu/nova-core/vbios.rs | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/nova-core/vbios.rs b/drivers/gpu/nova-core/vbios.rs
index a77d7a4c8595..cedfcf3476bb 100644
--- a/drivers/gpu/nova-core/vbios.rs
+++ b/drivers/gpu/nova-core/vbios.rs
@@ -893,6 +893,7 @@ fn try_from(base: BiosImageBase) -> Result<Self> {
 ///
 /// See the [`PmuLookupTable`] description for more information.
 #[expect(dead_code)]
+#[repr(C)]
 struct PmuLookupTableHeader {
     version: u8,
     header_len: u8,
@@ -901,16 +902,17 @@ struct PmuLookupTableHeader {
 }
 
 impl PmuLookupTableHeader {
+    // TODO[TRSM]: use FromBytes::from_bytes when it becomes available.
     fn new(data: &[u8]) -> Result<Self> {
         if data.len() < core::mem::size_of::<Self>() {
             return Err(EINVAL);
         }
 
         Ok(PmuLookupTableHeader {
-            version: data[0],
-            header_len: data[1],
-            entry_len: data[2],
-            entry_count: data[3],
+            version: data[const { core::mem::offset_of!(PmuLookupTableHeader, version) }],
+            header_len: data[const { core::mem::offset_of!(PmuLookupTableHeader, header_len) }],
+            entry_len: data[const { core::mem::offset_of!(PmuLookupTableHeader, entry_len) }],
+            entry_count: data[const { core::mem::offset_of!(PmuLookupTableHeader, entry_count) }],
         })
     }
 }

base-commit: 14ae91a81ec8fa0bc23170d4aa16dd2a20d54105
prerequisite-patch-id: 6f9311de987d56f4313d5fbdd85ed8c48a44e78c
-- 
2.50.1