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, 25 insertions, 0 deletions

diff --git a/fs/sysfs/Kconfig b/fs/sysfs/Kconfig
new file mode 100644
index 000000000..b0fe1cce3
--- /dev/null
+++ b/fs/sysfs/Kconfig
@@ -0,0 +1,25 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config SYSFS
+	bool "sysfs file system support" if EXPERT
+	default y
+	select KERNFS
+	help
+	The sysfs filesystem is a virtual filesystem that the kernel uses to
+	export internal kernel objects, their attributes, and their
+	relationships to one another.
+
+	Users can use sysfs to ascertain useful information about the running
+	kernel, such as the devices the kernel has discovered on each bus and
+	which driver each is bound to. sysfs can also be used to tune devices
+	and other kernel subsystems.
+
+	Some system agents rely on the information in sysfs to operate.
+	/sbin/hotplug uses device and object attributes in sysfs to assist in
+	delegating policy decisions, like persistently naming devices.
+
+	sysfs is currently used by the block subsystem to mount the root
+	partition.  If sysfs is disabled you must specify the boot device on
+	the kernel boot command line via its major and minor numbers.  For
+	example, "root=03:01" for /dev/hda1.
+
+	Designers of embedded systems may wish to say N here to conserve space.