gpu: nova-core: replace use of `as` with functions from `num`

Use the newly-introduced `num` module to replace the use of `as`
wherever it is safe to do. This ensures that a given conversion cannot
lose data if its source or destination type ever changes.

Acked-by: Danilo Krummrich <dakr@kernel.org>
[acourbot@nvidia.com: fix merge conflicts after rebase.]
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Message-ID: <20251029-nova-as-v3-5-6a30c7333ad9@nvidia.com>

1 files changed, 8 insertions, 4 deletions

diff --git a/drivers/gpu/nova-core/firmware.rs b/drivers/gpu/nova-core/firmware.rs
index 163b746f03ef..2d2008b33fb4 100644
--- a/drivers/gpu/nova-core/firmware.rs
+++ b/drivers/gpu/nova-core/firmware.rs
@@ -16,7 +16,11 @@ use kernel::{
 use crate::{
     dma::DmaObject,
     falcon::FalconFirmware,
-    gpu, //
+    gpu,
+    num::{
+        FromSafeCast,
+        IntoSafeCast, //
+    },
 };
 
 pub(crate) mod booter;
@@ -78,7 +82,7 @@ impl FalconUCodeDescV3 {
         const HDR_SIZE_SHIFT: u32 = 16;
         const HDR_SIZE_MASK: u32 = 0xffff0000;
 
-        ((self.hdr & HDR_SIZE_MASK) >> HDR_SIZE_SHIFT) as usize
+        ((self.hdr & HDR_SIZE_MASK) >> HDR_SIZE_SHIFT).into_safe_cast()
     }
 }
 
@@ -193,8 +197,8 @@ impl<'a> BinFirmware<'a> {
     /// Returns the data payload of the firmware, or `None` if the data range is out of bounds of
     /// the firmware image.
     fn data(&self) -> Option<&[u8]> {
-        let fw_start = self.hdr.data_offset as usize;
-        let fw_size = self.hdr.data_size as usize;
+        let fw_start = usize::from_safe_cast(self.hdr.data_offset);
+        let fw_size = usize::from_safe_cast(self.hdr.data_size);
 
         self.fw.get(fw_start..fw_start + fw_size)
     }