Add tests exercising the PCI configuration space helpers.

Suggested-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Zhi Wang <zhiw@nvidia.com>
---
 samples/rust/rust_driver_pci.rs | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/samples/rust/rust_driver_pci.rs b/samples/rust/rust_driver_pci.rs
index 528e672b6b89..f02ae6d089d0 100644
--- a/samples/rust/rust_driver_pci.rs
+++ b/samples/rust/rust_driver_pci.rs
@@ -58,6 +58,30 @@ fn testdev(index: &TestIndex, bar: &Bar0) -> Result<u32> {
 
         Ok(bar.read32(Regs::COUNT))
     }
+
+    fn config_space(pdev: &pci::Device<Core>) -> Result {
+        let config = pdev.config_space()?;
+
+        dev_info!(
+            pdev.as_ref(),
+            "pci-testdev config space try_read8 rev ID: {:x}\n",
+            config.try_read8(0x8)?
+        );
+
+        dev_info!(
+            pdev.as_ref(),
+            "pci-testdev config space try_read16 vendor ID: {:x}\n",
+            config.try_read16(0)?
+        );
+
+        dev_info!(
+            pdev.as_ref(),
+            "pci-testdev config space try_read32 BAR 0: {:x}\n",
+            config.try_read32(0x10)?
+        );
+
+        Ok(())
+    }
 }
 
 impl pci::Driver for SampleDriver {
@@ -93,6 +117,8 @@ fn probe(pdev: &pci::Device<Core>, info: &Self::IdInfo) -> Result<Pin<KBox<Self>
             Self::testdev(info, bar)?
         );
 
+        Self::config_space(pdev)?;
+
         Ok(drvdata)
     }
 
-- 
2.47.3

On Thu Oct 30, 2025 at 4:48 PM CET, Zhi Wang wrote:
> +    fn config_space(pdev: &pci::Device<Core>) -> Result {
> +        let config = pdev.config_space()?;
> +
> +        dev_info!(
> +            pdev.as_ref(),
> +            "pci-testdev config space try_read8 rev ID: {:x}\n",
> +            config.try_read8(0x8)?
> +        );
> +
> +        dev_info!(
> +            pdev.as_ref(),
> +            "pci-testdev config space try_read16 vendor ID: {:x}\n",
> +            config.try_read16(0)?
> +        );
> +
> +        dev_info!(
> +            pdev.as_ref(),
> +            "pci-testdev config space try_read32 BAR 0: {:x}\n",
> +            config.try_read32(0x10)?
> +        );
> +
> +        Ok(())
> +    }
>  }

Please use the infallible accessors and add a TODO to use the register!() macro
for defining PCI configuration space registers once it has been move out of
nova-core.