diff --git a/drivers/serial/sunzilog.c b/drivers/serial/sunzilog.c
index 18df10f49aff..47bc3d57e019 100644
--- a/drivers/serial/sunzilog.c
+++ b/drivers/serial/sunzilog.c
@@ -68,9 +68,6 @@ static int num_sunzilog;
 #define NUM_SUNZILOG	num_sunzilog
 #define NUM_CHANNELS	(NUM_SUNZILOG * 2)
 
-#define KEYBOARD_LINE 0x2
-#define MOUSE_LINE    0x3
-
 #define ZS_CLOCK		4915200 /* Zilog input clock rate. */
 #define ZS_CLOCK_DIVISOR	16      /* Divisor this driver uses. */
 
@@ -1225,12 +1222,10 @@ static void __init sunzilog_init_kbdms(struct uart_sunzilog_port *up, int channe
 {
 	int baud, brg;
 
-	if (channel == KEYBOARD_LINE) {
-		up->flags |= SUNZILOG_FLAG_CONS_KEYB;
+	if (up->flags & SUNZILOG_FLAG_CONS_KEYB) {
 		up->cflag = B1200 | CS8 | CLOCAL | CREAD;
 		baud = 1200;
 	} else {
-		up->flags |= SUNZILOG_FLAG_CONS_MOUSE;
 		up->cflag = B4800 | CS8 | CLOCAL | CREAD;
 		baud = 4800;
 	}
@@ -1243,14 +1238,14 @@ static void __init sunzilog_init_kbdms(struct uart_sunzilog_port *up, int channe
 }
 
 #ifdef CONFIG_SERIO
-static void __init sunzilog_register_serio(struct uart_sunzilog_port *up, int channel)
+static void __init sunzilog_register_serio(struct uart_sunzilog_port *up)
 {
 	struct serio *serio = &up->serio;
 
 	serio->port_data = up;
 
 	serio->id.type = SERIO_RS232;
-	if (channel == KEYBOARD_LINE) {
+	if (up->flags & SUNZILOG_FLAG_CONS_KEYB) {
 		serio->id.proto = SERIO_SUNKBD;
 		strlcpy(serio->name, "zskbd", sizeof(serio->name));
 	} else {
@@ -1259,7 +1254,8 @@ static void __init sunzilog_register_serio(struct uart_sunzilog_port *up, int ch
 		strlcpy(serio->name, "zsms", sizeof(serio->name));
 	}
 	strlcpy(serio->phys,
-		(channel == KEYBOARD_LINE ? "zs/serio0" : "zs/serio1"),
+		((up->flags & SUNZILOG_FLAG_CONS_KEYB) ?
+		 "zs/serio0" : "zs/serio1"),
 		sizeof(serio->phys));
 
 	serio->write = sunzilog_serio_write;
@@ -1286,8 +1282,8 @@ static void __init sunzilog_init_hw(struct uart_sunzilog_port *up)
 		(void) read_zsreg(channel, R0);
 	}
 
-	if (up->port.line == KEYBOARD_LINE ||
-	    up->port.line == MOUSE_LINE) {
+	if (up->flags & (SUNZILOG_FLAG_CONS_KEYB |
+			 SUNZILOG_FLAG_CONS_MOUSE)) {
 		sunzilog_init_kbdms(up, up->port.line);
 		up->curregs[R9] |= (NV | MIE);
 		write_zsreg(channel, R9, up->curregs[R9]);
@@ -1313,36 +1309,26 @@ static void __init sunzilog_init_hw(struct uart_sunzilog_port *up)
 	spin_unlock_irqrestore(&up->port.lock, flags);
 
 #ifdef CONFIG_SERIO
-	if (up->port.line == KEYBOARD_LINE || up->port.line == MOUSE_LINE)
-		sunzilog_register_serio(up, up->port.line);
+	if (up->flags & (SUNZILOG_FLAG_CONS_KEYB |
+			 SUNZILOG_FLAG_CONS_MOUSE))
+		sunzilog_register_serio(up);
 #endif
 }
 
-static int __devinit zs_get_instance(struct device_node *dp)
-{
-	int ret;
-
-	ret = of_getintprop_default(dp, "slave", -1);
-	if (ret != -1)
-		return ret;
-
-	if (of_find_property(dp, "keyboard", NULL))
-		ret = 1;
-	else
-		ret = 0;
-
-	return ret;
-}
-
 static int zilog_irq = -1;
 
 static int __devinit zs_probe(struct of_device *op, const struct of_device_id *match)
 {
+	static int inst;
 	struct uart_sunzilog_port *up;
 	struct zilog_layout __iomem *rp;
-	int inst = zs_get_instance(op->node);
+	int keyboard_mouse;
 	int err;
 
+	keyboard_mouse = 0;
+	if (of_find_property(op->node, "keyboard", NULL))
+		keyboard_mouse = 1;
+
 	sunzilog_chip_regs[inst] = of_ioremap(&op->resource[0], 0,
 					      sizeof(struct zilog_layout),
 					      "zs");
@@ -1369,7 +1355,7 @@ static int __devinit zs_probe(struct of_device *op, const struct of_device_id *m
 	up[0].port.line = (inst * 2) + 0;
 	up[0].port.dev = &op->dev;
 	up[0].flags |= SUNZILOG_FLAG_IS_CHANNEL_A;
-	if (inst == 1)
+	if (keyboard_mouse)
 		up[0].flags |= SUNZILOG_FLAG_CONS_KEYB;
 	sunzilog_init_hw(&up[0]);
 
@@ -1386,11 +1372,11 @@ static int __devinit zs_probe(struct of_device *op, const struct of_device_id *m
 	up[1].port.line = (inst * 2) + 1;
 	up[1].port.dev = &op->dev;
 	up[1].flags |= 0;
-	if (inst == 1)
+	if (keyboard_mouse)
 		up[1].flags |= SUNZILOG_FLAG_CONS_MOUSE;
 	sunzilog_init_hw(&up[1]);
 
-	if (inst != 1) {
+	if (!keyboard_mouse) {
 		err = uart_add_one_port(&sunzilog_reg, &up[0].port);
 		if (err) {
 			of_iounmap(rp, sizeof(struct zilog_layout));
@@ -1402,10 +1388,19 @@ static int __devinit zs_probe(struct of_device *op, const struct of_device_id *m
 			of_iounmap(rp, sizeof(struct zilog_layout));
 			return err;
 		}
+	} else {
+		printk(KERN_INFO "%s: Keyboard at MMIO %lx (irq = %d) "
+		       "is a zs\n",
+		       op->dev.bus_id, up[0].port.mapbase, op->irqs[0]);
+		printk(KERN_INFO "%s: Mouse at MMIO %lx (irq = %d) "
+		       "is a zs\n",
+		       op->dev.bus_id, up[1].port.mapbase, op->irqs[0]);
 	}
 
 	dev_set_drvdata(&op->dev, &up[0]);
 
+	inst++;
+
 	return 0;
 }
 
@@ -1454,10 +1449,15 @@ static int __init sunzilog_init(void)
 {
 	struct device_node *dp;
 	int err, uart_count;
+	int num_keybms;
 
 	NUM_SUNZILOG = 0;
-	for_each_node_by_name(dp, "zs")
+	num_keybms = 0;
+	for_each_node_by_name(dp, "zs") {
 		NUM_SUNZILOG++;
+		if (of_find_property(dp, "keyboard", NULL))
+			num_keybms++;
+	}
 
 	uart_count = 0;
 	if (NUM_SUNZILOG) {
@@ -1467,8 +1467,7 @@ static int __init sunzilog_init(void)
 		if (err)
 			goto out;
 
-		/* Subtract 1 for keyboard, 1 for mouse.  */
-		uart_count = (NUM_SUNZILOG * 2) - 2;
+		uart_count = (NUM_SUNZILOG * 2) - (2 * num_keybms);
 
 		sunzilog_reg.nr = uart_count;
 		sunzilog_reg.minor = sunserial_current_minor;