[RFC PATCH 2/2] samples: rust: add sample code for scatterlist bindings

[Abdiel Janulgue <abdiel.janulgue@gmail.com>]

Add simple excercises to test the scatterlist bindings.

Signed-off-by: Abdiel Janulgue <abdiel.janulgue@gmail.com>
---
 samples/rust/rust_dma.rs | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/samples/rust/rust_dma.rs b/samples/rust/rust_dma.rs
index 874c2c964afa..e3768c1a16b7 100644
--- a/samples/rust/rust_dma.rs
+++ b/samples/rust/rust_dma.rs
@@ -4,11 +4,15 @@
 //!
 //! To make this driver probe, QEMU must be run with `-device pci-testdev`.
 
-use kernel::{bindings, device::Core, dma::CoherentAllocation, pci, prelude::*, types::ARef};
+use kernel::{
+    bindings, device::Core, dma::CoherentAllocation, page::*, pci, prelude::*,
+    scatterlist::DmaDataDirection::*, scatterlist::*, types::ARef,
+};
 
 struct DmaSampleDriver {
     pdev: ARef<pci::Device>,
     ca: CoherentAllocation<MyStruct>,
+    _sgt: DeviceSGTable,
 }
 
 const TEST_VALUES: [(u32, u32); 5] = [
@@ -62,10 +66,18 @@ fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> Result<Pin<KBox<Self
             Ok(())
         }()?;
 
+        let mut sgt = DeviceSGTable::alloc_table(pdev.as_ref(), TEST_VALUES.len(), GFP_KERNEL)?;
+        for sg in sgt.iter_mut() {
+            sg.set_page(&Page::alloc_page(GFP_KERNEL)?, PAGE_SIZE as u32, 0);
+        }
+        sgt.dma_map(DmaToDevice)?;
+
         let drvdata = KBox::new(
             Self {
                 pdev: pdev.into(),
                 ca,
+                // Save object to excercise the destructor.
+                _sgt: sgt,
             },
             GFP_KERNEL,
         )?;
-- 
2.43.0