On Tue, Jul 15, 2025 at 09:53:22PM -0700, Matthew Wood wrote:
> 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 <thepacketgeek@xxxxxxxxx>
> ---
> drivers/pci/pci-sysfs.c | 23 ++++++++++++++++++++++-
> 1 file changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index 268c69daa4d5..d59756bc91c9 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 -EINVAL;
-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,
> };
>
> @@ -1749,8 +1766,12 @@ 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))
> + if (pci_is_pcie(pdev)) {
> + if (strncmp(a->name, "device_serial_number", 20) == 0 &&
Compare to the real 'struct attribute *' instead of the name.
You could restructure this a bit to be easier to read.
if (!pci_is_pcie(pdev))
return 0;
if (a == &dev_addr_device_serial_number.attr && !pci_get_dns(pdev))
return 0;
return a->mode;
> + !pci_get_dsn(pdev))
> + return 0;
> return a->mode;
> + }
Also should have some docs in Documentation/ABI/testing/sysfs-bus-pci.
>
> return 0;
> }
> --
> 2.50.0
>
