Commit 290b633a authored Oct 31, 2025 by Dan Williams

PCI: Establish document for PCI host bridge sysfs attributes

In preparation for adding more host bridge sysfs attributes, document the
existing naming format and 'firmware_node' attribute.

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Link: https://patch.msgid.link/20251031212902.2256310-7-dan.j.williams@intel.com

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

parent c0c1262f

Documentation/ABI/testing/sysfs-devices-pci-host-bridge

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Original line number	Diff line number	Diff line
		What: /sys/devices/pciDDDD:BB
		/sys/devices/.../pciDDDD:BB
		Contact: linux-pci@vger.kernel.org
		Description:
		A PCI host bridge device parents a PCI bus device topology. PCI
		controllers may also parent host bridges. The DDDD:BB format
		conveys the PCI domain (ACPI segment) number and root bus number
		(in hexadecimal) of the host bridge. Note that the domain number
		may be larger than the 16-bits that the "DDDD" format implies
		for emulated host-bridges.

		What: pciDDDD:BB/firmware_node
		Contact: linux-pci@vger.kernel.org
		Description:
		(RO) Symlink to the platform firmware device object "companion"
		of the host bridge. For example, an ACPI device with an _HID of
		PNP0A08 (/sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00). See
		/sys/devices/pciDDDD:BB entry for details about the DDDD:BB
		format.

MAINTAINERS

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		@@ -19910,6 +19910,7 @@ Q: https://patchwork.kernel.org/project/linux-pci/list/
		B: https://bugzilla.kernel.org
		C: irc://irc.oftc.net/linux-pci
		T: git git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git
		F: Documentation/ABI/testing/sysfs-devices-pci-host-bridge
		F: Documentation/PCI/
		F: Documentation/devicetree/bindings/pci/
		F: arch/x86/kernel/early-quirks.c