--- a/drivers/power/jz4740-battery.c
+++ b/drivers/power/jz4740-battery.c
@@ -47,6 +47,8 @@ struct jz_battery {
 
 	struct power_supply battery;
 	struct delayed_work work;
+
+	struct mutex lock;
 };
 
 static inline struct jz_battery *psy_to_jz_battery(struct power_supply *psy)
@@ -68,6 +70,8 @@ static long jz_battery_read_voltage(stru
 	unsigned long val;
 	long voltage;
 
+	mutex_lock(&battery->lock);
+
 	INIT_COMPLETION(battery->read_completion);
 
 	enable_irq(battery->irq);
@@ -91,6 +95,8 @@ static long jz_battery_read_voltage(stru
 	battery->cell->disable(battery->pdev);
 	disable_irq(battery->irq);
 
+	mutex_unlock(&battery->lock);
+
 	return voltage;
 }
 
@@ -240,6 +246,11 @@ static int __devinit jz_battery_probe(st
 	struct jz_battery *jz_battery;
 	struct power_supply *battery;
 
+	if (!pdata) {
+		dev_err(&pdev->dev, "No platform_data supplied\n");
+		return -ENXIO;
+	}
+
 	jz_battery = kzalloc(sizeof(*jz_battery), GFP_KERNEL);
 	if (!jz_battery) {
 		dev_err(&pdev->dev, "Failed to allocate driver structure\n");
@@ -291,6 +302,7 @@ static int __devinit jz_battery_probe(st
 	jz_battery->pdev = pdev;
 
 	init_completion(&jz_battery->read_completion);
+	mutex_init(&jz_battery->lock);
 
 	INIT_DELAYED_WORK(&jz_battery->work, jz_battery_work);