diff --git a/src/mainboard/intel/eagleheights/romstage.c b/src/mainboard/intel/eagleheights/romstage.c
index 8ffe22c168..8e1d212363 100644
--- a/src/mainboard/intel/eagleheights/romstage.c
+++ b/src/mainboard/intel/eagleheights/romstage.c
@@ -91,6 +91,8 @@ static inline int spd_read_byte(u16 device, u8 address)
 #include "northbridge/intel/i3100/reset_test.c"
 #include "debug.c"
 
+#define SERIAL_DEV PNP_DEV(0x4e, I3100_SP1)
+
 static void early_config(void)
 {
 	u32 gcs, rpc, fd;
@@ -157,7 +159,9 @@ void main(unsigned long bist)
 
 	/* Setup the console */
 	i3100_enable_superio();
-	i3100_enable_serial(0x4E, I3100_SP1, CONFIG_TTYS0_BASE);
+	i3100_enable_serial(SERIAL_DEV, CONFIG_TTYS0_BASE);
+	i3100_configure_uart_clk(SERIAL_DEV, I3100_UART_CLK_PREDIVIDE_26);
+
 	uart_init();
 	console_init();
 
diff --git a/src/mainboard/intel/mtarvon/romstage.c b/src/mainboard/intel/mtarvon/romstage.c
index 89fb5439ef..f36e4a4e68 100644
--- a/src/mainboard/intel/mtarvon/romstage.c
+++ b/src/mainboard/intel/mtarvon/romstage.c
@@ -40,6 +40,8 @@
 #define DEVPRES_CONFIG  (DEVPRES_D1F0 | DEVPRES_D2F0)
 #define DEVPRES1_CONFIG (DEVPRES1_D0F1 | DEVPRES1_D8F0)
 
+#define SERIAL_DEV PNP_DEV(0x4e, I3100_SP1)
+
 static inline int spd_read_byte(u16 device, u8 address)
 {
 	return smbus_read_byte(device, address);
@@ -75,9 +77,12 @@ void main(unsigned long bist)
 		}
 #endif
 	}
+
 	/* Set up the console */
 	i3100_enable_superio();
-	i3100_enable_serial(0x4e, I3100_SP1, CONFIG_TTYS0_BASE);
+	i3100_enable_serial(SERIAL_DEV, CONFIG_TTYS0_BASE);
+	i3100_configure_uart_clk(SERIAL_DEV, I3100_UART_CLK_PREDIVIDE_26);
+
 	uart_init();
 	console_init();
 
diff --git a/src/mainboard/intel/truxton/romstage.c b/src/mainboard/intel/truxton/romstage.c
index 3ef60b893e..4f85095d9f 100644
--- a/src/mainboard/intel/truxton/romstage.c
+++ b/src/mainboard/intel/truxton/romstage.c
@@ -15,7 +15,6 @@
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
- *
  */
 
 #include <stdint.h>
@@ -54,6 +53,8 @@ static inline int spd_read_byte(u16 device, u8 address)
 
 /* #define TRUXTON_DEBUG */
 
+#define SERIAL_DEV PNP_DEV(0x4e, I3100_SP1)
+
 static void main(unsigned long bist)
 {
 	msr_t msr;
@@ -76,7 +77,9 @@ static void main(unsigned long bist)
 
 	/* Set up the console */
 	i3100_enable_superio();
-	i3100_enable_serial(I3100_SUPERIO_CONFIG_PORT, I3100_SP1, CONFIG_TTYS0_BASE);
+	i3100_enable_serial(SERIAL_DEV, CONFIG_TTYS0_BASE);
+	i3100_configure_uart_clk(SERIAL_DEV, I3100_UART_CLK_PREDIVIDE_26);
+
 	uart_init();
 	console_init();
 
diff --git a/src/superio/intel/i3100/i3100.h b/src/superio/intel/i3100/i3100.h
index f0d6426be0..6218e6d09f 100644
--- a/src/superio/intel/i3100/i3100.h
+++ b/src/superio/intel/i3100/i3100.h
@@ -46,6 +46,19 @@
 #define I3100_SP2 0x05 /* Com2 */
 #define I3100_WDT 0x06 /* Watchdog timer */
 
-#define I3100_SUPERIO_CONFIG_PORT 0x4e
+/* Registers and bit definitions: */
+
+#define I3100_SIW_CONFIGURATION		0x29
+
+/*
+ * SIW_CONFIGURATION[3:2] = UART_CLK predivide
+ * 00: divide by 1
+ * 01: divide by 8
+ * 10: divide by 26
+ * 11: reserved
+ */
+#define I3100_UART_CLK_PREDIVIDE_1	0x00
+#define I3100_UART_CLK_PREDIVIDE_8	0x01
+#define I3100_UART_CLK_PREDIVIDE_26	0x02
 
 #endif
diff --git a/src/superio/intel/i3100/i3100_early_serial.c b/src/superio/intel/i3100/i3100_early_serial.c
index 74c20c537c..23f8cab5ab 100644
--- a/src/superio/intel/i3100/i3100_early_serial.c
+++ b/src/superio/intel/i3100/i3100_early_serial.c
@@ -21,31 +21,36 @@
 #include <arch/romcc_io.h>
 #include "i3100.h"
 
-static void i3100_sio_write(u8 port, u8 ldn, u8 index, u8 value)
+static void pnp_enter_ext_func_mode(device_t dev)
 {
-	outb(0x07, port);
-	outb(ldn, port + 1);
-	outb(index, port);
-	outb(value, port + 1);
-}
+	u16 port = dev >> 8;
 
-static void i3100_enable_serial(u8 port, u8 ldn, u16 iobase)
-{
-	/* Enter configuration state. */
 	outb(0x80, port);
 	outb(0x86, port);
+}
 
-	/* Enable serial port. */
-	i3100_sio_write(port, ldn, 0x30, 0x01);
+static void pnp_exit_ext_func_mode(device_t dev)
+{
+	u16 port = dev >> 8;
 
-	/* Set serial port I/O region. */
-	i3100_sio_write(port, ldn, 0x60, (iobase >> 8) & 0xff);
-	i3100_sio_write(port, ldn, 0x61, iobase & 0xff);
-
-	/* Enable device interrupts, set UART_CLK predivide to 26. */
-	i3100_sio_write(port, 0x00, 0x29, 0x0b);
-
-	/* Exit configuration state. */
 	outb(0x68, port);
 	outb(0x08, port);
 }
+
+/* Enable device interrupts, set UART_CLK predivide. */
+static void i3100_configure_uart_clk(device_t dev, u8 predivide)
+{
+	pnp_enter_ext_func_mode(dev);
+	pnp_write_config(dev, I3100_SIW_CONFIGURATION, (predivide << 2) | 1);
+	pnp_exit_ext_func_mode(dev);
+}
+
+static void i3100_enable_serial(device_t dev, u16 iobase)
+{
+	pnp_enter_ext_func_mode(dev);
+	pnp_set_logical_device(dev);
+	pnp_set_enable(dev, 0);
+	pnp_set_iobase(dev, PNP_IDX_IO0, iobase);
+	pnp_set_enable(dev, 1);
+	pnp_exit_ext_func_mode(dev);
+}