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Wed, 16 Jul 2025 09:32:17 -0700 (PDT) From: Matthew Wood To: Bjorn Helgaas Cc: "Jonathan Cameron" , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Subject: [PATCH v3 1/1] PCI/sysfs: Expose PCIe device serial number Date: Wed, 16 Jul 2025 09:32:11 -0700 Message-ID: <20250716163213.469226-2-thepacketgeek@gmail.com> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250716163213.469226-1-thepacketgeek@gmail.com> References: <20250716163213.469226-1-thepacketgeek@gmail.com> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add a single sysfs read-only interface for reading PCIe device serial numbers from userspace in a programmatic way. This device attribute uses the same hexadecimal 1-byte dashed formatting as lspci serial number capability output. If a device doesn't support the serial number capability, the device_serial_number sysfs attribute will not be visible. Signed-off-by: Matthew Wood --- Documentation/ABI/testing/sysfs-bus-pci | 7 +++++++ drivers/pci/pci-sysfs.c | 27 ++++++++++++++++++++++--- 2 files changed, 31 insertions(+), 3 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci index 69f952fffec7..f7e84b3a4204 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci +++ b/Documentation/ABI/testing/sysfs-bus-pci @@ -612,3 +612,10 @@ Description: # ls doe_features 0001:01 0001:02 doe_discovery + +What: /sys/bus/pci/devices/.../device_serial_number +Date: July 2025 +Contact: Matthew Wood +Description: + This is visible only for PCIe devices that support the serial + number extended capability. The file is read only. diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 268c69daa4d5..b7b52dea6e31 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -239,6 +239,22 @@ static ssize_t current_link_width_show(struct device *dev, } static DEVICE_ATTR_RO(current_link_width); +static ssize_t device_serial_number_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct pci_dev *pci_dev = to_pci_dev(dev); + u64 dsn; + + dsn = pci_get_dsn(pci_dev); + if (!dsn) + return -EIO; + + return sysfs_emit(buf, "%02llx-%02llx-%02llx-%02llx-%02llx-%02llx-%02llx-%02llx\n", + dsn >> 56, (dsn >> 48) & 0xff, (dsn >> 40) & 0xff, (dsn >> 32) & 0xff, + (dsn >> 24) & 0xff, (dsn >> 16) & 0xff, (dsn >> 8) & 0xff, dsn & 0xff); +} +static DEVICE_ATTR_RO(device_serial_number); + static ssize_t secondary_bus_number_show(struct device *dev, struct device_attribute *attr, char *buf) @@ -660,6 +676,7 @@ static struct attribute *pcie_dev_attrs[] = { &dev_attr_current_link_width.attr, &dev_attr_max_link_width.attr, &dev_attr_max_link_speed.attr, + &dev_attr_device_serial_number.attr, NULL, }; @@ -1749,10 +1766,14 @@ static umode_t pcie_dev_attrs_are_visible(struct kobject *kobj, struct device *dev = kobj_to_dev(kobj); struct pci_dev *pdev = to_pci_dev(dev); - if (pci_is_pcie(pdev)) - return a->mode; + if (!pci_is_pcie(pdev)) + return 0; + + if (a == &dev_attr_device_serial_number.attr && !pci_get_dsn(pdev)) + return 0; + + return a->mode; - return 0; } static const struct attribute_group pci_dev_group = { -- 2.50.0