[PATCH v3 2/8] rust: pci: add sriov_get_totalvfs() helper

[Zhi Wang]

Expose pci_sriov_get_totalvfs() to Rust PCI drivers so they can query
how many SR-IOV VFs a device supports.

Cc: Alexandre Courbot <acourbot@xxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: David Laight <david.laight.linux@xxxxxxxxx>
Cc: Gary Guo <gary@xxxxxxxxxxx>
Cc: linux-pci@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/all/DJHPRE4TGGT8.BUTMYOF5YE05@xxxxxxxxxx/
Signed-off-by: Zhi Wang <zhiw@xxxxxxxxxx>
---
 rust/kernel/pci.rs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index 5071cae6543f..21c51981c02e 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -450,6 +450,17 @@ pub fn pci_class(&self) -> Class {
         // SAFETY: `self.as_raw` is a valid pointer to a `struct pci_dev`.
         Class::from_raw(unsafe { (*self.as_raw()).class })
     }
+
+    /// Returns the total number of VFs, or 0 if SR-IOV is not available.
+    #[inline]
+    pub fn sriov_get_totalvfs(&self) -> u16 {
+        // SAFETY: `self.as_raw()` is a valid pointer to a `struct pci_dev`.
+        let total_vfs = unsafe { bindings::pci_sriov_get_totalvfs(self.as_raw()) };
+
+        // CAST: The C helper returns `unsigned int`, but the value originates
+        // from TotalVFs/driver_max_VFs, so this cast cannot truncate.
+        total_vfs as u16
+    }
 }
 
 impl<'a> Device<device::Core<'a>> {
-- 
2.51.0