---
 .../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 <pl...@plaes.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);
        if (error)
                return error;
 
+       error = input_register_device(lradc->input);
+       if (error) {
+               device_remove_file(&pdev->dev, &dev_attr_voltage);
+               return error;
+       }
+
        platform_set_drvdata(pdev, lradc);
        return 0;
 }
 
+static int sun4i_lradc_remove(struct platform_device *pdev)
+{
+       device_remove_file(&pdev->dev, &dev_attr_voltage);
+       return 0;
+}
+
 static const struct of_device_id sun4i_lradc_of_match[] = {
        { .compatible = "allwinner,sun4i-a10-lradc-keys", },
        { /* sentinel */ }
@@ -277,6 +305,7 @@ static struct platform_driver sun4i_lradc_driver = {
                .of_match_table = of_match_ptr(sun4i_lradc_of_match),
        },
        .probe  = sun4i_lradc_probe,
+       .remove = sun4i_lradc_remove,
 };
 
 module_platform_driver(sun4i_lradc_driver);
-- 
2.2.2

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