diff --git a/hw/Makefile.objs b/hw/Makefile.objs
index af93dfc..4ec6fb8 100644
--- a/hw/Makefile.objs
+++ b/hw/Makefile.objs
@@ -117,7 +117,7 @@ common-obj-$(CONFIG_PCNET_COMMON) += pcnet.o
 common-obj-$(CONFIG_E1000_PCI) += e1000.o
 common-obj-$(CONFIG_RTL8139_PCI) += rtl8139.o
 
-common-obj-$(CONFIG_SMC91C111) += smc91c111.o
+common-obj-$(CONFIG_SMC91C111) += smc91c111.o mdio.o
 common-obj-$(CONFIG_LAN9118) += lan9118.o
 common-obj-$(CONFIG_NE2000_ISA) += ne2000-isa.o
 common-obj-$(CONFIG_OPENCORES_ETH) += opencores_eth.o
diff --git a/hw/smc91c111.c b/hw/smc91c111.c
index a34698f..c1b3678 100644
--- a/hw/smc91c111.c
+++ b/hw/smc91c111.c
@@ -10,6 +10,7 @@
 #include "sysbus.h"
 #include "net/net.h"
 #include "devices.h"
+#include "mdio.h"
 /* For crc32 */
 #include <zlib.h>
 
@@ -44,6 +45,10 @@ typedef struct {
     uint8_t int_level;
     uint8_t int_mask;
     MemoryRegion mmio;
+
+    /* MDIO bus and the attached phy */
+    struct qemu_mdio mdio_bus;
+    struct qemu_phy phy;
 } smc91c111_state;
 
 static const VMStateDescription vmstate_smc91c111 = {
@@ -71,6 +76,8 @@ static const VMStateDescription vmstate_smc91c111 = {
         VMSTATE_BUFFER_UNSAFE(data, smc91c111_state, 0, NUM_PACKETS * 2048),
         VMSTATE_UINT8(int_level, smc91c111_state),
         VMSTATE_UINT8(int_mask, smc91c111_state),
+        VMSTATE_MDIO(mdio_bus, smc91c111_state),
+        VMSTATE_MDIO_PHY(phy, smc91c111_state),
         VMSTATE_END_OF_LIST()
     }
 };
@@ -437,8 +444,16 @@ static void smc91c111_writeb(void *opaque, hwaddr offset,
             /* Multicast table.  */
             /* Not implemented.  */
             return;
-        case 8: case 9: /* Management Interface.  */
-            /* Not implemented.  */
+        case 8: /* Management Interface.  */
+            /* Update MDIO data line status; but only if output is enabled */
+            if (value & 8) {
+                s->mdio_bus.mdio = !!(value & 1);
+            }
+            /* Process the clock */
+            mdio_cycle(&s->mdio_bus, value & 4);
+            return;
+        case 9: /* Management Interface.  */
+            /* Not implemented */
             return;
         case 12: /* Early receive.  */
             s->ercv = value & 0x1f;
@@ -576,8 +591,7 @@ static uint32_t smc91c111_readb(void *opaque, hwaddr offset)
             /* Not implemented.  */
             return 0;
         case 8: /* Management Interface.  */
-            /* Not implemented.  */
-            return 0x30;
+            return 0x30 | (s->mdio_bus.mdio ? 2 : 0);
         case 9:
             return 0x33;
         case 10: /* Revision.  */
@@ -754,6 +768,9 @@ static int smc91c111_init1(SysBusDevice *dev)
     s->nic = qemu_new_nic(&net_smc91c111_info, &s->conf,
                           object_get_typename(OBJECT(dev)), dev->qdev.id, s);
     qemu_format_nic_info_str(&s->nic->nc, s->conf.macaddr.a);
+
+    tdk_init(&s->phy);
+    mdio_attach(&s->mdio_bus, &s->phy, 0);
     /* ??? Save/restore.  */
     return 0;
 }