[PATCH v8 6/9] PCI: Establish document for PCI host bridge sysfs attributes

Dan Williams
2025-10-31T21:29:05Z

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

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
---
.../ABI/testing/sysfs-devices-pci-host-bridge | 19 +++++++++++++++++++
MAINTAINERS | 1 +
2 files changed, 20 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-devices-pci-host-bridge

diff --git a/Documentation/ABI/testing/sysfs-devices-pci-host-bridge b/Documentation/ABI/testing/sysfs-devices-pci-host-bridge
new file mode 100644
index 000000000000..8c3a652799f1
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-pci-host-bridge
@@ -0,0 +1,19 @@
+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.
diff --git a/MAINTAINERS b/MAINTAINERS
index ebf6988666eb..9b961fb11b09 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19896,6 +19896,7 @@ 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
--
2.51.0