diff --git a/arch/arm/src/stm32/stm32_eth.c b/arch/arm/src/stm32/stm32_eth.c
index 2197665b32..0d86cd605a 100644
--- a/arch/arm/src/stm32/stm32_eth.c
+++ b/arch/arm/src/stm32/stm32_eth.c
@@ -665,6 +665,9 @@ static void stm32_rxdescinit(FAR struct stm32_ethmac_s *priv);
 
 /* PHY Initialization */
 
+#ifdef CONFIG_NETDEV_PHY_IOCTL
+static int  stm32_ioctl(int cmd, struct mii_ioctl_data *req);
+#endif
 static int  stm32_phyread(uint16_t phydevaddr, uint16_t phyregaddr, uint16_t *value);
 static int  stm32_phywrite(uint16_t phydevaddr, uint16_t phyregaddr, uint16_t value);
 #ifdef CONFIG_ETH0_PHY_DM9161
@@ -2475,6 +2478,63 @@ static void stm32_rxdescinit(FAR struct stm32_ethmac_s *priv)
   stm32_putreg((uint32_t)priv->rxtable, STM32_ETH_DMARDLAR);
 }
 
+/****************************************************************************
+ * Function: stm32_ioctl
+ *
+ * Description:
+ *  Executes the SIOCxMIIxxx command and responds using the request struct
+ *  that must be provided as its 2nd parameter.
+ *
+ *  When called with SIOCGMIIPHY it will get the PHY address for the device
+ *  and write it to the req->phy_id field of the request struct.
+ *
+ *  When called with SIOCGMIIREG it will read a register of the PHY that is
+ *  specified using the req->reg_no struct field and then write its output
+ *  to the req->val_out field.
+ *
+ *  When called with SIOCSMIIREG it will write to a register of the PHY that
+ *  is specified using the req->reg_no struct field and use req->val_in as
+ *  its input.
+ *
+ * Parameters:
+ *   cmd - SIOCxMIIxxx command code
+ *   req - request structure also used to return values
+ *
+ * Returned Value: Negated errno on failure.
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_NETDEV_PHY_IOCTL
+static int stm32_ioctl(int cmd, struct mii_ioctl_data *req)
+{
+  int ret = -ENOTTY;
+
+  switch (cmd)
+  {
+  case SIOCGMIIPHY: /* Get MII PHY address */
+    req->phy_id = CONFIG_STM32_PHYADDR;
+    ret = OK;
+    break;
+
+  case SIOCGMIIREG: /* Get register from MII PHY */
+    ret = stm32_phyread(req->phy_id, req->reg_num, &req->val_out);
+    break;
+
+  case SIOCSMIIREG: /* Set register in MII PHY */
+    ret = stm32_phywrite(req->phy_id, req->reg_num, req->val_in);
+    break;
+
+  default:
+    ret = -EINVAL;
+    break;
+  }
+
+  return ret;
+}
+#endif /* CONFIG_NETDEV_PHY_IOCTL */
+
 /****************************************************************************
  * Function: stm32_phyread
  *
@@ -3460,6 +3520,9 @@ int stm32_ethinitialize(int intf)
 #ifdef CONFIG_NET_IGMP
   priv->dev.d_addmac  = stm32_addmac;   /* Add multicast MAC address */
   priv->dev.d_rmmac   = stm32_rmmac;    /* Remove multicast MAC address */
+#endif
+#ifdef CONFIG_NETDEV_PHY_IOCTL
+  priv->dev.d_ioctl   = stm32_ioctl;    /* Support PHY ioctl() calls */
 #endif
   priv->dev.d_private = (void*)g_stm32ethmac; /* Used to recover private state from dev */
 
diff --git a/include/net/if.h b/include/net/if.h
index eae6bcb3fc..bad4a21240 100644
--- a/include/net/if.h
+++ b/include/net/if.h
@@ -57,11 +57,22 @@
 #define IFF_RUNNING     (1 << 2)
 #define IFF_NOARP       (1 << 7)
 
-
 /*******************************************************************************************
  * Public Type Definitions
  *******************************************************************************************/
 
+/* Part of the I/F request used to read from or write to the MII/PHY management
+ * interface when SIOCxMIIREG ioctl was called.
+ */
+
+struct mii_ioctl_data
+{
+  uint16_t phy_id;      /* PHY device address */
+  uint16_t reg_num;     /* PHY register address */
+  uint16_t val_in;      /* PHY input data */
+  uint16_t val_out;     /* PHY output data */
+};
+
 /* This is the newer form if the I/F request structure that can be used with both IPv4
  * and IPv6.
  */
@@ -79,6 +90,7 @@ struct lifreq
     int                     lifru_count;              /* Number of devices */
     int                     lifru_mtu;                /* MTU size */
     uint8_t                 lifru_flags;              /* Interface flags */
+    struct mii_ioctl_data   lifru_mii_data;           /* MII request data */
   } lifr_ifru;
 };
 
@@ -90,6 +102,10 @@ struct lifreq
 #define lifr_mtu            lifr_ifru.lifru_mtu       /* MTU */
 #define lifr_count          lifr_ifru.lifru_count     /* Number of devices */
 #define lifr_flags          lifr_ifru.lifru_flags     /* interface flags */
+#define lifr_mii_phy_id     lifr_ifru.lifru_mii_data.phy_id  /* PHY device address */
+#define lifr_mii_reg_num    lifr_ifru.lifru_mii_data.reg_num /* PHY register address */
+#define lifr_mii_val_in     lifr_ifru.lifru_mii_data.val_in  /* PHY input data */
+#define lifr_mii_val_out    lifr_ifru.lifru_mii_data.val_out /* PHY output data */
 
 /* This is the older I/F request that should only be used with IPv4.  However, since
  * NuttX only supports IPv4 or 6 (not both), we can force the older structure to
@@ -110,6 +126,7 @@ struct ifreq
     int                     ifru_count;               /* Number of devices */
     int                     ifru_mtu;                 /* MTU size */
     uint8_t                 ifru_flags;               /* Interface flags */
+    struct mii_ioctl_data   ifru_mii_data;            /* MII request data */
   } ifr_ifru;
 };
 
@@ -121,6 +138,10 @@ struct ifreq
 #define ifr_mtu             ifr_ifru.ifru_mtu         /* MTU */
 #define ifr_count           ifr_ifru.ifru_count       /* Number of devices */
 #define ifr_flags           ifr_ifru.ifru_flags       /* interface flags */
+#define ifr_mii_phy_id      ifr_ifru.ifru_mii_data.phy_id  /* PHY device address */
+#define ifr_mii_reg_num     ifr_ifru.ifru_mii_data.reg_num /* PHY register address */
+#define ifr_mii_val_in      ifr_ifru.ifru_mii_data.val_in  /* PHY input data */
+#define ifr_mii_val_out     ifr_ifru.ifru_mii_data.val_out /* PHY output data */
 
 #else /* CONFIG_NET_IPv6 */
 
@@ -134,6 +155,10 @@ struct ifreq
 #define ifr_mtu             lifr_ifru.lifru_mtu       /* MTU */
 #define ifr_count           lifr_ifru.lifru_count     /* Number of devices */
 #define ifr_flags           lifr_ifru.lifru_flags     /* interface flags */
+#define ifr_mii_phy_id      lifr_ifru.lifru_mii_data.phy_id  /* PHY device address */
+#define ifr_mii_reg_num     lifr_ifru.lifru_mii_data.reg_num /* PHY register address */
+#define ifr_mii_val_in      lifr_ifru.lifru_mii_data.val_in  /* PHY input data */
+#define ifr_mii_val_out     lifr_ifru.lifru_mii_data.val_out /* PHY output data */
 
 #endif /* CONFIG_NET_IPv6 */
 
diff --git a/include/nuttx/net/ioctl.h b/include/nuttx/net/ioctl.h
index 7fbcc3b201..7c2e1cb497 100644
--- a/include/nuttx/net/ioctl.h
+++ b/include/nuttx/net/ioctl.h
@@ -160,6 +160,12 @@
 
 #define SIOCSIWPMKSA     _SIOC(0x0041) /* PMKSA cache operation */
 
+/* MDIO/MCD *****************************************************************/
+
+#define SIOCGMIIPHY      _SIOC(0x0042) /* Get address of MII PHY in use */
+#define SIOCGMIIREG      _SIOC(0x0043) /* Get a MII register via MDIO */
+#define SIOCSMIIREG      _SIOC(0x0044) /* Set a MII register via MDIO */
+
 /****************************************************************************
  * Type Definitions
  ****************************************************************************/
diff --git a/include/nuttx/net/netdev.h b/include/nuttx/net/netdev.h
index 0537587381..cc781a77df 100644
--- a/include/nuttx/net/netdev.h
+++ b/include/nuttx/net/netdev.h
@@ -187,6 +187,9 @@ struct uip_driver_s
   int (*d_addmac)(struct uip_driver_s *dev, FAR const uint8_t *mac);
   int (*d_rmmac)(struct uip_driver_s *dev, FAR const uint8_t *mac);
 #endif
+#ifdef CONFIG_NETDEV_PHY_IOCTL
+  int (*d_ioctl)(int cmd, struct mii_ioctl_data *req);
+#endif
 
   /* Drivers may attached device-specific, private information */
 
diff --git a/net/Kconfig b/net/Kconfig
index 294ea523e4..8440b4dc1d 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -73,6 +73,12 @@ config NET_SOCKOPTS
 	---help---
 		Enable or disable support for socket options
 
+config NETDEV_PHY_IOCTL
+	bool "Enable PHY ioctl()"
+	default n
+	---help---
+		Enable support for ioctl() commands to access PHY registers"
+
 if NET_SOCKOPTS
 
 config NET_SOLINGER
diff --git a/net/netdev_ioctl.c b/net/netdev_ioctl.c
index 1505e668fe..ec216a1e47 100644
--- a/net/netdev_ioctl.c
+++ b/net/netdev_ioctl.c
@@ -422,6 +422,21 @@ static int netdev_ifrioctl(FAR struct socket *psock, int cmd,
 # error "IOCTL Commands not implemented"
 #endif
 
+#ifdef CONFIG_NETDEV_PHY_IOCTL
+      case SIOCGMIIPHY: /* Get address of MII PHY in use */
+      case SIOCGMIIREG: /* Get MII register via MDIO */
+      case SIOCSMIIREG: /* Set MII register via MDIO */
+        {
+          dev = netdev_ifrdev(req);
+          if (dev && dev->d_ioctl)
+            {
+              struct mii_ioctl_data *mii_data = &req->ifr_ifru.ifru_mii_data;
+              ret = dev->d_ioctl(cmd, mii_data);
+            }
+        }
+        break;
+#endif
+
       default:
         {
           ret = -ENOTTY;