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, 113 insertions, 0 deletions

diff --git a/Documentation/gpu/drm-ras.rst b/Documentation/gpu/drm-ras.rst
new file mode 100644
index 000000000..83c21853b
--- /dev/null
+++ b/Documentation/gpu/drm-ras.rst
@@ -0,0 +1,113 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+============================
+DRM RAS over Generic Netlink
+============================
+
+The DRM RAS (Reliability, Availability, Serviceability) interface provides a
+standardized way for GPU/accelerator drivers to expose error counters and
+other reliability nodes to user space via Generic Netlink. This allows
+diagnostic tools, monitoring daemons, or test infrastructure to query hardware
+health in a uniform way across different DRM drivers.
+
+Key Goals:
+
+* Provide a standardized RAS solution for GPU and accelerator drivers, enabling
+  data center monitoring and reliability operations.
+* Implement a single drm-ras Generic Netlink family to meet modern Netlink YAML
+  specifications and centralize all RAS-related communication in one namespace.
+* Support a basic error counter interface, addressing the immediate, essential
+  monitoring needs.
+* Offer a flexible, future-proof interface that can be extended to support
+  additional types of RAS data in the future.
+* Allow multiple nodes per driver, enabling drivers to register separate
+  nodes for different IP blocks, sub-blocks, or other logical subdivisions
+  as applicable.
+
+.. contents::
+
+Nodes
+=====
+
+Nodes are logical abstractions representing an error type or error source within
+the device. Currently, only error counter nodes is supported.
+
+Drivers are responsible for registering and unregistering nodes via the
+`drm_ras_node_register()` and `drm_ras_node_unregister()` APIs.
+
+Node Management
+-------------------
+
+.. kernel-doc:: drivers/gpu/drm/drm_ras.c
+   :doc: DRM RAS Node Management
+.. kernel-doc:: drivers/gpu/drm/drm_ras.c
+   :internal:
+
+Generic Netlink Usage
+=====================
+
+The interface is implemented as a Generic Netlink family named ``drm-ras``.
+User space tools can:
+
+* List registered nodes with the ``list-nodes`` command.
+* List all error counters in an node with the ``get-error-counter`` command with ``node-id``
+  as a parameter.
+* Query specific error counter values with the ``get-error-counter`` command, using both
+  ``node-id`` and ``error-id`` as parameters.
+* Clear specific error counters with the ``clear-error-counter`` command, using both
+  ``node-id`` and ``error-id`` as parameters.
+
+YAML-based Interface
+--------------------
+
+The interface is described in a YAML specification ``Documentation/netlink/specs/drm_ras.yaml``
+
+This YAML is used to auto-generate user space bindings via
+``tools/net/ynl/pyynl/ynl_gen_c.py``, and drives the structure of netlink
+attributes and operations.
+
+Usage Notes
+-----------
+
+* User space must first enumerate nodes to obtain their IDs.
+* Node IDs or Node names can be used for all further queries, such as error counters.
+* Error counters can be queried by either the Error ID or Error name.
+* Query Parameters should be defined as part of the uAPI to ensure user interface stability.
+* The interface supports future extension by adding new node types and
+  additional attributes.
+
+Example: List nodes using ynl
+
+.. code-block:: bash
+
+    sudo ynl --family drm_ras --dump list-nodes
+    [{'device-name': '0000:03:00.0',
+    'node-id': 0,
+    'node-name': 'correctable-errors',
+    'node-type': 'error-counter'},
+    {'device-name': '0000:03:00.0',
+     'node-id': 1,
+     'node-name': 'uncorrectable-errors',
+     'node-type': 'error-counter'}]
+
+Example: List all error counters using ynl
+
+.. code-block:: bash
+
+    sudo ynl --family drm_ras --dump get-error-counter --json '{"node-id":0}'
+    [{'error-id': 1, 'error-name': 'error_name1', 'error-value': 0},
+    {'error-id': 2, 'error-name': 'error_name2', 'error-value': 0}]
+
+Example: Query an error counter for a given node
+
+.. code-block:: bash
+
+    sudo ynl --family drm_ras --do get-error-counter --json '{"node-id":0, "error-id":1}'
+    {'error-id': 1, 'error-name': 'error_name1', 'error-value': 0}
+
+Example: Clear an error counter for a given node
+
+.. code-block:: bash
+
+    sudo ynl --family drm_ras --do clear-error-counter --json '{"node-id":0, "error-id":1}'
+    None