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Fri, 01 Aug 2025 11:13:29 -0700 (PDT) From: Matthew Wood To: Bjorn Helgaas Cc: "Mario Limonciello" , "Jonathan Cameron" , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= , Jonathan Cameron , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Subject: [PATCH v7 1/1] PCI/sysfs: Expose PCIe device serial number Date: Fri, 1 Aug 2025 11:13:24 -0700 Message-ID: <20250801181326.1782789-2-thepacketgeek@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250801181326.1782789-1-thepacketgeek@gmail.com> References: <20250801181326.1782789-1-thepacketgeek@gmail.com> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 serial_number sysfs attribute will not be visible. Signed-off-by: Matthew Wood Reviewed-by: Mario Limonciello Reviewed-by: Jonathan Cameron Reviewed-by: Thomas Weißschuh --- Documentation/ABI/testing/sysfs-bus-pci | 9 +++++++++ drivers/pci/pci-sysfs.c | 27 ++++++++++++++++++++++--- 2 files changed, 33 insertions(+), 3 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci index 69f952fffec7..d5251f4f3659 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci +++ b/Documentation/ABI/testing/sysfs-bus-pci @@ -612,3 +612,12 @@ Description: # ls doe_features 0001:01 0001:02 doe_discovery + +What: /sys/bus/pci/devices/.../serial_number +Date: December 2025 +Contact: Matthew Wood +Description: + This is visible only for PCIe devices that support the serial + number extended capability. The file is read only and due to + the possible sensitivity of accessible serial numbers, admin + only. diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 268c69daa4d5..1d26e4336f1b 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -30,6 +30,7 @@ #include #include #include +#include #include "pci.h" #ifndef ARCH_PCI_DEV_GROUPS @@ -239,6 +240,22 @@ static ssize_t current_link_width_show(struct device *dev, } static DEVICE_ATTR_RO(current_link_width); +static ssize_t serial_number_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct pci_dev *pci_dev = to_pci_dev(dev); + u64 dsn; + u8 bytes[8]; + + dsn = pci_get_dsn(pci_dev); + if (!dsn) + return -EIO; + put_unaligned_be64(dsn, bytes); + + return sysfs_emit(buf, "%8phD\n", bytes); +} +static DEVICE_ATTR_ADMIN_RO(serial_number); + static ssize_t secondary_bus_number_show(struct device *dev, struct device_attribute *attr, char *buf) @@ -660,6 +677,7 @@ 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_serial_number.attr, NULL, }; @@ -1749,10 +1767,13 @@ 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; - return 0; + if (a == &dev_attr_serial_number.attr && !pci_get_dsn(pdev)) + return 0; + + return a->mode; } static const struct attribute_group pci_dev_group = { -- 2.50.1