rust: pci: provide access to PCI Class and Class-related items

Allow callers to write Class::STORAGE_SCSI instead of
bindings::PCI_CLASS_STORAGE_SCSI, for example.

New APIs:
    Class::STORAGE_SCSI, Class::NETWORK_ETHERNET, etc.
    Class::from_raw() -- Only callable from pci module.
    Class::as_raw()
    ClassMask: Full, ClassSubclass
    Device::pci_class()

Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Elle Rhumsaa <elle@weathered-steel.dev>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Link: https://lore.kernel.org/r/20250829223632.144030-2-jhubbard@nvidia.com
[ Minor doc-comment improvements, align Debug and Display. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index cae4e274f776..72d38f23f914 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -24,6 +24,10 @@ use core::{
 };
 use kernel::prelude::*;
 
+mod id;
+
+pub use self::id::{Class, ClassMask};
+
 /// An adapter for the registration of PCI drivers.
 pub struct Adapter<T: Driver>(T);
 
@@ -459,6 +463,13 @@ impl Device {
         // - by its type invariant `self.as_raw` is always a valid pointer to a `struct pci_dev`.
         Ok(unsafe { bindings::pci_resource_len(self.as_raw(), bar.try_into()?) })
     }
+
+    /// Returns the PCI class as a `Class` struct.
+    #[inline]
+    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 })
+    }
 }
 
 impl Device<device::Bound> {