rust: pci: make Bar lifetime-parameterized

Convert pci::Bar<SIZE> to pci::Bar<'a, SIZE>, storing &'a Device<Bound>
to tie the BAR mapping lifetime to the device.

iomap_region_sized() now returns Result<Bar<'a, SIZE>> directly instead
of impl PinInit<Devres<Bar<SIZE>>, Error>.

Since the lifetime ties the mapping to the device's bound state, callers
no longer need Devres for the common case where the Bar lives in the
driver's private data.

Add Bar::into_devres() to consume the bar and register it as a
device-managed resource, returning Devres<Bar<'static, SIZE>>. The
lifetime is erased to 'static because Devres guarantees the bar does not
actually outlive the device -- access is revoked on unbind.

Reviewed-by: Eliot Courtney <ecourtney@nvidia.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260525202921.124698-19-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index 6ad1a856694c..7dbec0470c26 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -45,7 +45,7 @@ const BAR0_SIZE: usize = SZ_16M;
 // DMA addresses. These systems should be quite rare.
 const GPU_DMA_BITS: u32 = 47;
 
-pub(crate) type Bar0 = pci::Bar<BAR0_SIZE>;
+pub(crate) type Bar0 = pci::Bar<'static, BAR0_SIZE>;
 
 kernel::pci_device_table!(
     PCI_TABLE,
@@ -92,8 +92,9 @@ impl pci::Driver for NovaCore {
             // other threads of execution.
             unsafe { pdev.dma_set_mask_and_coherent(DmaMask::new::<GPU_DMA_BITS>())? };
 
-            let bar = Arc::pin_init(
-                pdev.iomap_region_sized::<BAR0_SIZE>(0, c"nova-core/bar0"),
+            let bar = Arc::new(
+                pdev.iomap_region_sized::<BAR0_SIZE>(0, c"nova-core/bar0")?
+                    .into_devres()?,
                 GFP_KERNEL,
             )?;