[PATCH v2 1/4] rust: pci: make Vendor::from_raw() public

[Maurice Hieronymus]

`Vendor::from_raw()` is currently `pub(super)`, so a Vendor can only be
obtained through the named constants generated from the
`PCI_VENDOR_ID_*` defines in `<linux/pci_ids.h>`. A driver therefore
cannot match a device whose vendor ID has no symbolic name.

Such devices exist. QEMU's "edu" educational device and the legacy
qemu/Bochs stdvga both use vendor ID 0x1234, which is not registered in
`pci_ids.h`. Per the policy stated at the top of that header, IDs are
only added there when shared between multiple drivers; a single-driver
ID is expected to be open-coded in the driver instead. C drivers already
do this -- see `drivers/gpu/drm/tiny/bochs.c`, which matches with a bare
".vendor = 0x1234".

The Rust abstraction has no equivalent escape hatch: there is no public
way to express an unregistered vendor. Make `Vendor::from_raw()` public
(and const, so it can be used in the const device-ID tables built by
`pci_device_table!`) so that drivers can construct a Vendor from a raw
ID, matching what C drivers can already do.

Reviewed-by: Gary Guo <gary@xxxxxxxxxxx>
Signed-off-by: Maurice Hieronymus <mhi@xxxxxxxxxxx>
---
 rust/kernel/pci/id.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/kernel/pci/id.rs b/rust/kernel/pci/id.rs
index dbaf301666e7..fe3b0047179b 100644
--- a/rust/kernel/pci/id.rs
+++ b/rust/kernel/pci/id.rs
@@ -156,7 +156,7 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 impl Vendor {
     /// Create a Vendor from a raw 16-bit vendor ID.
     #[inline]
-    pub(super) fn from_raw(vendor_id: u16) -> Self {
+    pub const fn from_raw(vendor_id: u16) -> Self {
         Self(vendor_id)
     }
 

-- 
2.51.2