[PATCH 06/14] rust: pci: add is_physfn(), to check for PFs

[Zhi Wang <zhiw@nvidia.com>]

From: Peter Colberg <pcolberg@redhat.com>

Add a method to check if a PCI device is a Physical Function (PF).

zhiw: Keep this role check private to the PCI SR-IOV implementation
instead of extending the public `Device` API. Add a dead-code
expectation because this standalone API commit has no in-tree caller.

Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Peter Colberg <pcolberg@redhat.com>
Signed-off-by: Zhi Wang <zhiw@nvidia.com>
---
 rust/kernel/pci.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index 844d73a83670..ed42511911d7 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -507,6 +507,14 @@ pub fn resource_start(&self, bar: u32) -> Result<bindings::resource_size_t> {
         Ok(unsafe { bindings::pci_resource_start(self.as_raw(), bar.try_into()?) })
     }
 
+    /// Returns `true` if this device is a Physical Function (PF).
+    #[inline]
+    #[expect(dead_code)]
+    pub(crate) fn is_physfn(&self) -> bool {
+        // SAFETY: `self.as_raw` is a valid pointer to a `struct pci_dev`.
+        unsafe { (*self.as_raw()).is_physfn() != 0 }
+    }
+
     /// Returns `true` if this device is a Virtual Function (VF).
     #[inline]
     #[expect(dead_code)]