[PATCH] rust: pci: rework device enabling API

[Maurice Hieronymus]

`enable_device_mem()` wraps the unmanaged `pci_enable_device_mem()` and has
no disable counterpart, so the enable count is leaked on driver unbind.

Replace it with:

- `enable_device_managed()`, wrapping `pcim_enable_device()`, which
  registers a `pci_disable_device()` cleanup that runs on unbind; this
  is what drivers should normally call in `probe()`.

- an unmanaged `enable_device()`/`disable_device()` pair, wrapping
  `pci_enable_device()`/`pci_disable_device()`, e.g. for runtime PM
  paths.

Unlike `pci_enable_device_mem()`, both variants enable I/O and memory
resources.

Convert nova-core and the rust_driver_pci sample, the only users of
`enable_device_mem()`, to `enable_device_managed()`; besides gaining the
automatic cleanup they now also enables I/O resources.

This is a prerequisite for the EDU PCI sample driver series [1], as
requested by Danilo in its review [2]; that series will be rebased on
top of this patch.

Link: https://lore.kernel.org/r/20260620-b4-rust-pci-edu-driver-v2-0-6fd6684f2c14@xxxxxxxxxxx [1]
Link: https://lore.kernel.org/rust-for-linux/DJEPMYC7J6ZG.D0ODUD4YGFCT@xxxxxxxxxx/ [2]
Suggested-by: Danilo Krummrich <dakr@xxxxxxxxxx>
Signed-off-by: Maurice Hieronymus <mhi@xxxxxxxxxxx>
---
Replace pci::Device::enable_device_mem() with a managed
enable_device_managed() plus an unmanaged enable_device()/
disable_device() pair, and convert the two users (nova-core and the
rust_driver_pci sample).

Requested by Danilo [2] while reviewing the EDU PCI sample driver
series [1]; that series will be rebased on top of this one.

[1] https://lore.kernel.org/r/20260620-b4-rust-pci-edu-driver-v2-0-6fd6684f2c14@xxxxxxxxxxx
[2] https://lore.kernel.org/rust-for-linux/DJEPMYC7J6ZG.D0ODUD4YGFCT@xxxxxxxxxx
---
 drivers/gpu/nova-core/driver.rs |  2 +-
 rust/kernel/pci.rs              | 26 +++++++++++++++++++++++---
 samples/rust/rust_driver_pci.rs |  2 +-
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index 5738d4ac521b..b0711d98033b 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -75,7 +75,7 @@ fn probe<'bound>(
         pin_init::pin_init_scope(move || {
             dev_dbg!(pdev, "Probe Nova Core GPU driver.\n");
 
-            pdev.enable_device_mem()?;
+            pdev.enable_device_managed()?;
             pdev.set_master();
 
             Ok(try_pin_init!(NovaCore {
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index 5071cae6543f..a408b3412077 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -453,10 +453,30 @@ pub fn pci_class(&self) -> Class {
 }
 
 impl<'a> Device<device::Core<'a>> {
-    /// Enable memory resources for this device.
-    pub fn enable_device_mem(&self) -> Result {
+    /// Enable I/O and memory resources for this device.
+    ///
+    /// This function is unmanaged and does not perform any cleanup when the device is unbound.
+    /// For a managed function take a look at [`Device::enable_device_managed`].
+    #[inline]
+    pub fn enable_device(&self) -> Result {
+        // SAFETY: `self.as_raw` is guaranteed to be a pointer to a valid `struct pci_dev`.
+        to_result(unsafe { bindings::pci_enable_device(self.as_raw()) })
+    }
+
+    /// Disable I/O and memory resources for this device.
+    ///
+    /// This function is the counterpart to [`Device::enable_device`].
+    #[inline]
+    pub fn disable_device(&self) {
+        // SAFETY: `self.as_raw` is guaranteed to be a pointer to a valid `struct pci_dev`.
+        unsafe { bindings::pci_disable_device(self.as_raw()) }
+    }
+
+    /// Enable I/O and memory resources for this device, with automatic cleanup.
+    #[inline]
+    pub fn enable_device_managed(&self) -> Result {
         // SAFETY: `self.as_raw` is guaranteed to be a pointer to a valid `struct pci_dev`.
-        to_result(unsafe { bindings::pci_enable_device_mem(self.as_raw()) })
+        to_result(unsafe { bindings::pcim_enable_device(self.as_raw()) })
     }
 
     /// Enable bus-mastering for this device.
diff --git a/samples/rust/rust_driver_pci.rs b/samples/rust/rust_driver_pci.rs
index 1aa8197d8698..213ef14386ca 100644
--- a/samples/rust/rust_driver_pci.rs
+++ b/samples/rust/rust_driver_pci.rs
@@ -154,7 +154,7 @@ fn probe<'bound>(
             pdev.device_id()
         );
 
-        pdev.enable_device_mem()?;
+        pdev.enable_device_managed()?;
         pdev.set_master();
 
         let bar = pdev.iomap_region_sized::<{ regs::END }>(0, c"rust_driver_pci")?;

---
base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482
change-id: 20260702-rust-pci-enable-device-managed-155eb5de8603

Best regards,
-- 
Maurice Hieronymus <mhi@xxxxxxxxxxx>