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authorDan Williams <dan.j.williams@intel.com>2025-10-31 14:28:58 -0700
committerDan Williams <dan.j.williams@intel.com>2025-11-03 19:27:41 -0800
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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>
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diff --git a/Documentation/ABI/testing/sysfs-devices-pci-host-bridge b/Documentation/ABI/testing/sysfs-devices-pci-host-bridge
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+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.