PCI: Add pci_irq_type() to query the allocated interrupt typegrafted

Add a helper that returns PCI_IRQ_MSIX, PCI_IRQ_MSI, or PCI_IRQ_INTX
based on the interrupt type the PCI core selected after
pci_alloc_irq_vectors().

Several drivers already open-code this check against pdev->msix_enabled
and pdev->msi_enabled, or even open code this helper [1].

A common helper avoids the duplication and keeps drivers from accessing
the bitfield directly (see also [2]).

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: John Hubbard <jhubbard@nvidia.com>
Link: https://elixir.bootlin.com/linux/v7.1/source/drivers/net/ethernet/aquantia/atlantic/aq_pci_func.c#L196 [1]
Inspired-by: John Hubbard <jhubbard@nvidia.com>
Link: https://lore.kernel.org/all/DKKG2QM3YJYB.Z2H2B2UXJ75N@kernel.org/ [2]
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260813165234.620555-5-dakr@kernel.org
[ Add missing pci_irq_type() stub for CONFIG_PCI=n. ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

1 files changed, 69 insertions, 0 deletions

diff --git a/Documentation/gpu/nova/guidelines.rst b/Documentation/gpu/nova/guidelines.rst
new file mode 100644
index 000000000..13ab13984
--- /dev/null
+++ b/Documentation/gpu/nova/guidelines.rst
@@ -0,0 +1,69 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+==========
+Guidelines
+==========
+
+This document describes the general project guidelines that apply to nova-core
+and nova-drm.
+
+Language
+========
+
+The Nova project uses the Rust programming language. In this context, all rules
+of the Rust for Linux project as documented in
+:doc:`../../rust/general-information` apply. Additionally, the following rules
+apply.
+
+- Unless technically necessary otherwise (e.g. uAPI), any driver code is written
+  in Rust.
+
+- Unless technically necessary, unsafe Rust code must be avoided. In case of
+  technical necessity, unsafe code should be isolated in a separate component
+  providing a safe API for other driver code to use.
+
+Style
+-----
+
+All rules of the Rust for Linux project as documented in
+:doc:`../../rust/coding-guidelines` apply.
+
+For a submit checklist, please also see the `Rust for Linux Submit checklist
+addendum <https://rust-for-linux.com/contributing#submit-checklist-addendum>`_.
+
+Documentation
+=============
+
+The availability of proper documentation is essential in terms of scalability,
+accessibility for new contributors and maintainability of a project in general,
+but especially for a driver running as complex hardware as Nova is targeting.
+
+Hence, adding documentation of any kind is very much encouraged by the project.
+
+Besides that, there are some minimum requirements.
+
+- Every non-private structure needs at least a brief doc comment explaining the
+  semantical sense of the structure, as well as potential locking and lifetime
+  requirements. It is encouraged to have the same minimum documentation for
+  non-trivial private structures.
+
+- uAPIs must be fully documented with kernel-doc comments; additionally, the
+  semantical behavior must be explained including potential special or corner
+  cases.
+
+- The APIs connecting the 1st level driver (nova-core) with 2nd level drivers
+  must be fully documented. This includes doc comments, potential locking and
+  lifetime requirements, as well as example code if applicable.
+
+- Abbreviations must be explained when introduced; terminology must be uniquely
+  defined.
+
+- Register addresses, layouts, shift values and masks must be defined properly;
+  unless obvious, the semantical sense must be documented. This only applies if
+  the author is able to obtain the corresponding information.
+
+Acceptance Criteria
+===================
+
+- Patches must only be applied if reviewed by at least one other person on the
+  mailing list; this also applies for maintainers.