[PATCH v4 1/9] rust: pci: add PCI device name method

[Timur Tabi <ttabi@nvidia.com>]

Add a name() method to the PCI `Device` type, which returns a CStr
that contains the device name, typically the BDF address.

Signed-off-by: Timur Tabi <ttabi@nvidia.com>
---
 rust/kernel/pci.rs | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index 82e128431f08..125fb39f4316 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -427,6 +427,43 @@ 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 PCI device name.
+    ///
+    /// This returns the device name in the format "DDDD:BB:DD.F" where:
+    /// - DDDD is the PCI domain (4 hex digits)
+    /// - BB is the bus number (2 hex digits)
+    /// - DD is the device number (2 hex digits)
+    /// - F is the function number (1 hex digit)
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use kernel::{c_str, debugfs::Dir, device::Core, pci, prelude::*};
+    /// fn create_debugfs(pdev: &pci::Device<Core>) -> Result {
+    ///     let dir = Dir::new(pdev.name());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[inline]
+    pub fn name(&self) -> &CStr {
+        // SAFETY: By its type invariant `self.as_raw` is always a valid pointer to a
+        // `struct pci_dev`, which contains a `struct device dev` member.
+        unsafe {
+            let pci_dev = self.as_raw();
+            let dev = &raw const (*pci_dev).dev;
+
+            // If init_name is set, use it; otherwise use the kobject name
+            let init_name = (*dev).init_name;
+            let name_ptr = if !init_name.is_null() {
+                init_name
+            } else {
+                (*dev).kobj.name
+            };
+
+            CStr::from_char_ptr(name_ptr)
+        }
+    }
 }
 
 impl Device<device::Core> {
-- 
2.52.0