phylib: mdio: Add sysfs attribute for PHY identifiers.

This adds a phy_id sysfs attribute to MDIO devices, containing the
32-bit PHY identifier reported by the device.  This attribute can
be useful when debugging problems related to phy drivers.  Other
enumerable buses already have similar attributes.

Signed-off-by: Nick Bowler <nbowler@elliptictech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index c1ef3000ea60..044b5326459f 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -431,10 +431,24 @@ static struct dev_pm_ops mdio_bus_pm_ops = {
 
 #endif /* CONFIG_PM */
 
+static ssize_t
+phy_id_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+        struct phy_device *phydev = to_phy_device(dev);
+
+        return sprintf(buf, "0x%.8lx\n", (unsigned long)phydev->phy_id);
+}
+
+static struct device_attribute mdio_dev_attrs[] = {
+        __ATTR_RO(phy_id),
+        __ATTR_NULL
+};
+
 struct bus_type mdio_bus_type = {
         .name           = "mdio_bus",
         .match          = mdio_bus_match,
         .pm             = MDIO_BUS_PM_OPS,
+        .dev_attrs      = mdio_dev_attrs,
 };
 EXPORT_SYMBOL(mdio_bus_type);