.../ABI/testing/sysfs-driver-input-sun4i-lradc     |  4 ++
 drivers/input/keyboard/sun4i-lradc-keys.c          | 49 +++++++++++++++++-----
 2 files changed, 43 insertions(+), 10 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-driver-input-sun4i-lradc

diff --git a/Documentation/ABI/testing/sysfs-driver-input-sun4i-lradc b/Documentation/ABI/testing/sysfs-driver-input-sun4i-lradc
new file mode 100644
index 0000000..e4e6448
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-input-sun4i-lradc

@@ -0,0 +1,4 @@
+What:		/sys/class/input/input(x)/device/voltage
+Date:		February 2015
+Contact:	Priit Laes <plaes-q/aMd4JkU83YtjvyW6yDsg@public.gmane.org>
+Description:	ADC output voltage in microvolts or 0 if device is not opened.

diff --git a/drivers/input/keyboard/sun4i-lradc-keys.c b/drivers/input/keyboard/sun4i-lradc-keys.c
index cc8f7dd..c0ab8ec 100644
--- a/drivers/input/keyboard/sun4i-lradc-keys.c
+++ b/drivers/input/keyboard/sun4i-lradc-keys.c

@@ -79,10 +79,27 @@ struct sun4i_lradc_data {
 	u32 vref;
 };
 
+static u32 sun4i_lradc_read_voltage(struct sun4i_lradc_data *lradc)
+{
+	u32 val = readl(lradc->base + LRADC_DATA0) & 0x3f;
+	return val * lradc->vref / 63;
+};
+
+static ssize_t
+sun4i_lradc_dev_voltage_show(struct device *dev,
+			struct device_attribute *attr, char *buf)
+{
+	struct sun4i_lradc_data *lradc = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", sun4i_lradc_read_voltage(lradc));
+}
+
+static const DEVICE_ATTR(voltage, S_IRUGO, sun4i_lradc_dev_voltage_show, NULL);
+
 static irqreturn_t sun4i_lradc_irq(int irq, void *dev_id)
 {
 	struct sun4i_lradc_data *lradc = dev_id;
-	u32 i, ints, val, voltage, diff, keycode = 0, closest = 0xffffffff;
+	u32 i, ints, voltage, diff, keycode = 0, closest = 0xffffffff;
 
 	ints  = readl(lradc->base + LRADC_INTS);
 

@@ -97,8 +114,7 @@ static irqreturn_t sun4i_lradc_irq(int irq, void *dev_id)
 	}
 
 	if ((ints & CHAN0_KEYDOWN_IRQ) && lradc->chan0_keycode == 0) {
-		val = readl(lradc->base + LRADC_DATA0) & 0x3f;
-		voltage = val * lradc->vref / 63;
+		voltage = sun4i_lradc_read_voltage(lradc);
 
 		for (i = 0; i < lradc->chan0_map_count; i++) {
 			diff = abs(lradc->chan0_map[i].voltage - voltage);

@@ -156,7 +172,7 @@ static void sun4i_lradc_close(struct input_dev *dev)
 }
 
 static int sun4i_lradc_load_dt_keymap(struct device *dev,
-				      struct sun4i_lradc_data *lradc)
+				    struct sun4i_lradc_data *lradc)
 {
 	struct device_node *np, *pp;
 	int i;

@@ -168,8 +184,8 @@ static int sun4i_lradc_load_dt_keymap(struct device *dev,
 
 	lradc->chan0_map_count = of_get_child_count(np);
 	if (lradc->chan0_map_count == 0) {
-		dev_err(dev, "keymap is missing in device tree\n");
-		return -EINVAL;
+		dev_info(dev, "keymap is missing in device tree\n");
+		return 0;
 	}
 
 	lradc->chan0_map = devm_kmalloc_array(dev, lradc->chan0_map_count,

@@ -185,19 +201,19 @@ static int sun4i_lradc_load_dt_keymap(struct device *dev,
 
 		error = of_property_read_u32(pp, "channel", &channel);
 		if (error || channel != 0) {
-			dev_err(dev, "%s: Inval channel prop\n", pp->name);
+			dev_err(dev, "%s: Invalid 'channel' property\n", pp->name);
 			return -EINVAL;
 		}
 
 		error = of_property_read_u32(pp, "voltage", &map->voltage);
 		if (error) {
-			dev_err(dev, "%s: Inval voltage prop\n", pp->name);
+			dev_err(dev, "%s: Invalid 'voltage' property\n", pp->name);
 			return -EINVAL;
 		}
 
 		error = of_property_read_u32(pp, "linux,code", &map->keycode);
 		if (error) {
-			dev_err(dev, "%s: Inval linux,code prop\n", pp->name);
+			dev_err(dev, "%s: Invalid 'linux,code' property\n", pp->name);
 			return -EINVAL;
 		}
 

@@ -257,14 +273,26 @@ static int sun4i_lradc_probe(struct platform_device *pdev)
 	if (error)
 		return error;
 
-	error = input_register_device(lradc->input);
+	error = device_create_file(dev, &dev_attr_voltage);