[PATCH 1/2] rust: dma: make use of start_ptr() and start_ptr_mut()

[Danilo Krummrich]

Using start_ptr() and start_ptr_mut() has the advantage that we inherit
the requirements the a mutable or immutable reference from those
methods.

Hence, use them instead of self.cpu_addr.

Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
---
 rust/kernel/dma.rs | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/rust/kernel/dma.rs b/rust/kernel/dma.rs
index 4e0af3e1a3b9..f066cbb53cfa 100644
--- a/rust/kernel/dma.rs
+++ b/rust/kernel/dma.rs
@@ -505,7 +505,7 @@ pub unsafe fn as_slice(&self, offset: usize, count: usize) -> Result<&[T]> {
         //   data is also guaranteed by the safety requirements of the function.
         // - `offset + count` can't overflow since it is smaller than `self.count` and we've checked
         //   that `self.count` won't overflow early in the constructor.
-        Ok(unsafe { core::slice::from_raw_parts(self.cpu_addr.add(offset), count) })
+        Ok(unsafe { core::slice::from_raw_parts(self.start_ptr().add(offset), count) })
     }
 
     /// Performs the same functionality as [`CoherentAllocation::as_slice`], except that a mutable
@@ -525,7 +525,7 @@ pub unsafe fn as_slice_mut(&mut self, offset: usize, count: usize) -> Result<&mu
         //   data is also guaranteed by the safety requirements of the function.
         // - `offset + count` can't overflow since it is smaller than `self.count` and we've checked
         //   that `self.count` won't overflow early in the constructor.
-        Ok(unsafe { core::slice::from_raw_parts_mut(self.cpu_addr.add(offset), count) })
+        Ok(unsafe { core::slice::from_raw_parts_mut(self.start_ptr_mut().add(offset), count) })
     }
 
     /// Writes data to the region starting from `offset`. `offset` is in units of `T`, not the
@@ -557,7 +557,11 @@ pub unsafe fn write(&mut self, src: &[T], offset: usize) -> Result {
         // - `offset + count` can't overflow since it is smaller than `self.count` and we've checked
         //   that `self.count` won't overflow early in the constructor.
         unsafe {
-            core::ptr::copy_nonoverlapping(src.as_ptr(), self.cpu_addr.add(offset), src.len())
+            core::ptr::copy_nonoverlapping(
+                src.as_ptr(),
+                self.start_ptr_mut().add(offset),
+                src.len(),
+            )
         };
         Ok(())
     }
@@ -576,7 +580,7 @@ pub fn item_from_index(&self, offset: usize) -> Result<*mut T> {
         // and we've just checked that the range and index is within bounds.
         // - `offset` can't overflow since it is smaller than `self.count` and we've checked
         // that `self.count` won't overflow early in the constructor.
-        Ok(unsafe { self.cpu_addr.add(offset) })
+        Ok(unsafe { self.start_ptr().cast_mut().add(offset) })
     }
 
     /// Reads the value of `field` and ensures that its type is [`FromBytes`].
@@ -637,7 +641,7 @@ fn drop(&mut self) {
             bindings::dma_free_attrs(
                 self.dev.as_raw(),
                 size,
-                self.cpu_addr.cast(),
+                self.start_ptr_mut().cast(),
                 self.dma_handle,
                 self.dma_attrs.as_raw(),
             )
-- 
2.51.0