[PATCH v3 2/2] rust: Add several miscellaneous PCI helpers

[Alistair Popple]

Add bindings to obtain a PCI device's resource start address, bus/
device function, revision ID and subsystem device and vendor IDs.

These will be used by the nova-core GPU driver which is currently in
development.

Reviewed-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
Cc: Danilo Krummrich <dakr@xxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Krzysztof Wilczyński <kwilczynski@xxxxxxxxxx>
Cc: Miguel Ojeda <ojeda@xxxxxxxxxx>
Cc: Alex Gaynor <alex.gaynor@xxxxxxxxx>
Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
Cc: Gary Guo <gary@xxxxxxxxxxx>
Cc: Björn Roy Baron <bjorn3_gh@xxxxxxxxxxxxxx>
Cc: Benno Lossin <lossin@xxxxxxxxxx>
Cc: Andreas Hindborg <a.hindborg@xxxxxxxxxx>
Cc: Alice Ryhl <aliceryhl@xxxxxxxxxx>
Cc: Trevor Gross <tmgross@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Rafael J. Wysocki <rafael@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Alexandre Courbot <acourbot@xxxxxxxxxx>
Cc: linux-pci@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx>

---

Changes for v3:

 - Fixed capitalisation of SAFETY comments.
 - There was a long discussion about the SAFETY comments on v2 of the
   series[1]. I don't think anything actionable came of it so I haven't
   made any changes as a result of that discussion.

[1] - https://lore.kernel.org/rust-for-linux/20250710022415.923972-1-apopple@xxxxxxxxxx/
---
 rust/helpers/pci.c | 10 ++++++++++
 rust/kernel/pci.rs | 44 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/rust/helpers/pci.c b/rust/helpers/pci.c
index cd0e6bf2cc4d9..59d15bd4bdb13 100644
--- a/rust/helpers/pci.c
+++ b/rust/helpers/pci.c
@@ -12,6 +12,16 @@ void *rust_helper_pci_get_drvdata(struct pci_dev *pdev)
 	return pci_get_drvdata(pdev);
 }
 
+u16 rust_helper_pci_dev_id(struct pci_dev *dev)
+{
+	return PCI_DEVID(dev->bus->number, dev->devfn);
+}
+
+resource_size_t rust_helper_pci_resource_start(struct pci_dev *pdev, int bar)
+{
+	return pci_resource_start(pdev, bar);
+}
+
 resource_size_t rust_helper_pci_resource_len(struct pci_dev *pdev, int bar)
 {
 	return pci_resource_len(pdev, bar);
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index 7da1712398938..d47226a679f6c 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -386,6 +386,50 @@ pub fn device_id(&self) -> u16 {
         unsafe { (*self.as_raw()).device }
     }
 
+    /// Returns the PCI revision ID.
+    #[inline]
+    pub fn revision_id(&self) -> u8 {
+        // SAFETY: By its type invariant `self.as_raw` is always a valid pointer to a
+        // `struct pci_dev`.
+        unsafe { (*self.as_raw()).revision }
+    }
+
+    /// Returns the PCI bus device/function.
+    #[inline]
+    pub fn dev_id(&self) -> u16 {
+        // SAFETY: By its type invariant `self.as_raw` is always a valid pointer to a
+        // `struct pci_dev`.
+        unsafe { bindings::pci_dev_id(self.as_raw()) }
+    }
+
+    /// Returns the PCI subsystem vendor ID.
+    #[inline]
+    pub fn subsystem_vendor_id(&self) -> u16 {
+        // SAFETY: By its type invariant `self.as_raw` is always a valid pointer to a
+        // `struct pci_dev`.
+        unsafe { (*self.as_raw()).subsystem_vendor }
+    }
+
+    /// Returns the PCI subsystem device ID.
+    #[inline]
+    pub fn subsystem_device_id(&self) -> u16 {
+        // SAFETY: By its type invariant `self.as_raw` is always a valid pointer to a
+        // `struct pci_dev`.
+        unsafe { (*self.as_raw()).subsystem_device }
+    }
+
+    /// Returns the start of the given PCI bar resource.
+    pub fn resource_start(&self, bar: u32) -> Result<bindings::resource_size_t> {
+        if !Bar::index_is_valid(bar) {
+            return Err(EINVAL);
+        }
+
+        // SAFETY:
+        // - `bar` is a valid bar number, as guaranteed by the above call to `Bar::index_is_valid`,
+        // - by its type invariant `self.as_raw` is always a valid pointer to a `struct pci_dev`.
+        Ok(unsafe { bindings::pci_resource_start(self.as_raw(), bar.try_into()?) })
+    }
+
     /// Returns the size of the given PCI bar resource.
     pub fn resource_len(&self, bar: u32) -> Result<bindings::resource_size_t> {
         if !Bar::index_is_valid(bar) {
-- 
2.47.2