[PATCH v2 0/4] rust: samples: add an EDU PCI driver sample (MMIO + IRQ + DMA)

[Maurice Hieronymus]

The Rust sample drivers currently exercise PCI facilities in isolation:
rust_driver_pci covers MMIO and rust_dma covers DMA, but there is no
single in-tree example that combines memory-mapped I/O, interrupts and
DMA in one driver.

This series adds one. It targets QEMU's `edu` device -- a small,
well-documented educational PCI device that supports exactly these three
facilities and ships with any recent QEMU (`-device edu`), so the sample
runs without special hardware.

The sample maps BAR0 and runs a set of MMIO self-tests (identification,
liveness, factorial), allocates an MSI vector and registers an IRQ
handler, and performs a DMA round-trip -- each stage waiting on a
Completion that the IRQ handler signals.

Prerequisites, that had to be implemented:

- pci: make Vendor::from_raw() public, so a driver can match a device
  whose vendor ID has no symbolic name in pci_ids.h (QEMU's 0x1234),
  matching what C drivers already do.
- pci: add a managed enable_device() wrapping pcim_enable_device(), so
  the enable count stays balanced across unbind/rebind.
- completion: add complete(), so a single Completion can be reused to
  wait for consecutive events (e.g. back-to-back DMA transfers).

Tested with QEMU `-device edu`;

Signed-off-by: Maurice Hieronymus <mhi@xxxxxxxxxxx>
---
Changes in v2:
- pci: Vendor::from_raw(): collected Reviewed-by from Gary Guo;
  wrapped code identifiers in the commit message in backticks (Gary).
- pci: enable_device(): collected Reviewed-by from Fiona Behrens;
  made enable_device_mem() #[inline] and added a cross-reference to
  enable_device() in its docs (Fiona).
- completion: complete(): tightened the doc comment per Gary's review
  (emphasise "single", drop the internal-counter detail, drop the
  complete_all comparison).
- samples/edu: take &EduDriverData instead of &Arc<EduDriverData> in
  init()/test_irq()/test_dma() (Ewan Chorynski).
- samples/edu: simplify wait_until_compute_has_finished() to forward
  read_poll_timeout()'s error via inspect_err() instead of returning a
  hard-coded ETIMEDOUT (Ewan Chorynski / Miguel Ojeda).
- samples/edu: Rebased on rust/rust-next and adapt to the updated
  pci::Bar / device::Core lifetimes and pci::Driver::Data<'bound>, and
  obtain the BAR via into_devres().
- Link to v1: https://lore.kernel.org/r/20260614-b4-rust-pci-edu-driver-v1-0-e3f2471b595c@xxxxxxxxxxx

---
Maurice Hieronymus (4):
      rust: pci: make Vendor::from_raw() public
      rust: pci: add managed Device::enable_device()
      rust: completion: add complete()
      rust: samples: add EDU PCI driver sample

 rust/kernel/pci.rs              |  16 ++
 rust/kernel/pci/id.rs           |   2 +-
 rust/kernel/sync/completion.rs  |  11 ++
 samples/rust/Kconfig            |  11 ++
 samples/rust/Makefile           |   1 +
 samples/rust/rust_driver_edu.rs | 378 ++++++++++++++++++++++++++++++++++++++++
 6 files changed, 418 insertions(+), 1 deletion(-)
---
base-commit: 43a393185e33e573a374c1d4f7ddf6481484ef8d
change-id: 20260614-b4-rust-pci-edu-driver-3e50db2dda0f

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