rust: pci: expose the allocated interrupt type

Add irq_type() on IrqVectorRegistration and IrqVector, wrapping the new
pci_irq_type() C function. A driver whose interrupt acknowledgment
depends on the type (MSI-X vs MSI vs INTx) queries it here rather than
assuming which type the PCI core selected.

Tested-by: John Hubbard <jhubbard@nvidia.com>
Suggested-by: John Hubbard <jhubbard@nvidia.com>
Link: https://lore.kernel.org/all/20260808031120.363869-4-jhubbard@nvidia.com/
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260813165234.620555-6-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

rust/helpers/pci.c

@@ -24,6 +24,11 @@ __rust_helper bool rust_helper_dev_is_pci(const struct device *dev)
 	return dev_is_pci(dev);
 }
 
+__rust_helper unsigned int rust_helper_pci_irq_type(struct pci_dev *pdev)
+{
+	return pci_irq_type(pdev);
+}
+
 #ifndef CONFIG_PCI_MSI
 __rust_helper int rust_helper_pci_alloc_irq_vectors(struct pci_dev *dev,
 						    unsigned int min_vecs,

rust/kernel/pci/irq.rs

@@ -33,6 +33,16 @@ const fn as_raw(self) -> u32 {
             IrqType::MsiX => bindings::PCI_IRQ_MSIX,
         }
     }
+
+    /// Construct from raw value.
+    #[inline]
+    const fn from_raw(raw: u32) -> Self {
+        match raw {
+            bindings::PCI_IRQ_MSIX => IrqType::MsiX,
+            bindings::PCI_IRQ_MSI => IrqType::Msi,
+            _ => IrqType::Intx,
+        }
+    }
 }
 
 /// Set of IRQ types that can be used for PCI interrupt allocation.
@@ -90,6 +100,12 @@ unsafe fn new(request: IrqRequest<'a>, reg: &'a IrqVectorRegistration<'a>) -> Se
     pub fn vectors(&self) -> &'a IrqVectorRegistration<'a> {
         self.reg
     }
+
+    /// Returns the interrupt type the PCI core selected for this vector's allocation.
+    #[inline]
+    pub fn irq_type(&self) -> IrqType {
+        self.reg.irq_type()
+    }
 }
 
 impl<'a> From<IrqVector<'a>> for IrqRequest<'a> {
@@ -122,6 +138,13 @@ pub fn len(&self) -> usize {
         self.len.get()
     }
 
+    /// Returns the interrupt type the PCI core selected for this allocation.
+    #[inline]
+    pub fn irq_type(&self) -> IrqType {
+        // SAFETY: `self.dev.as_raw()` is a valid pointer to a `struct pci_dev`.
+        IrqType::from_raw(unsafe { bindings::pci_irq_type(self.dev.as_raw()) })
+    }
+
     /// Returns the [`IrqVector`] at `index`.
     ///
     /// Returns [`EINVAL`] if the `index` is out of bounds for the length reported by