ZYNQ_GEM_DMACR_TXSIZE | \
                                        ZYNQ_GEM_DMACR_RXBUF)
 
+/* Use MII register 1 (MII status register) to detect PHY */
+#define PHY_DETECT_REG  1
+
+/* Mask used to verify certain PHY features (or register contents)
+ * in the register above:
+ *  0x1000: 10Mbps full duplex support
+ *  0x0800: 10Mbps half duplex support
+ *  0x0008: Auto-negotiation support
+ */
+#define PHY_DETECT_MASK 0x1808
+
 /* Device registers */
 struct zynq_gem_regs {
        u32 nwctrl; /* Network Control reg */
                                ZYNQ_GEM_PHYMNTNC_OP_W_MASK, &data);
 }
 
+static void phy_detection(struct eth_device *dev)
+{
+       int i;
+       u16 phyreg;
+       struct zynq_gem_priv *priv = dev->priv;
+
+       if (priv->phyaddr != -1) {
+               phyread(dev, priv->phyaddr, PHY_DETECT_REG, &phyreg);
+               if ((phyreg != 0xFFFF) &&
+                   ((phyreg & PHY_DETECT_MASK) == PHY_DETECT_MASK)) {
+                       /* Found a valid PHY address */
+                       debug("Default phy address %d is valid\n",
+                             priv->phyaddr);
+                       return;
+               } else {
+                       debug("PHY address is not setup correctly %d\n",
+                             priv->phyaddr);
+                       priv->phyaddr = -1;
+               }
+       }
+
+       debug("detecting phy address\n");
+       if (priv->phyaddr == -1) {
+               /* detect the PHY address */
+               for (i = 31; i >= 0; i--) {
+                       phyread(dev, i, PHY_DETECT_REG, &phyreg);
+                       if ((phyreg != 0xFFFF) &&
+                           ((phyreg & PHY_DETECT_MASK) == PHY_DETECT_MASK)) {
+                               /* Found a valid PHY address */
+                               priv->phyaddr = i;
+                               debug("Found valid phy address, %d\n", i);
+                               return;
+                       }
+               }
+       }
+       printf("PHY is not detected\n");
+}
+
 static int zynq_gem_setup_mac(struct eth_device *dev)
 {
        u32 i, macaddrlow, macaddrhigh;
                priv->init++;
        }
 
+       phy_detection(dev);
+
        /* interface - look at tsec */
        phydev = phy_connect(priv->bus, priv->phyaddr, dev, 0);