iio: vcnl4000: Export near level property for proximity sensor

When an object can be considered close to the sensor is hardware
dependent. Allowing to configure the property via device tree
allows to configure this device specific value.

This is useful for e.g. iio-sensor-proxy to indicate to userspace
if an object is close to the sensor.
Signed-off-by: Guido Günther <agx@sigxcpu.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/light/vcnl4000.c

@@ -83,6 +83,7 @@ struct vcnl4000_data {
 	struct mutex vcnl4000_lock;
 	struct vcnl4200_channel vcnl4200_al;
 	struct vcnl4200_channel vcnl4200_ps;
+	uint32_t near_level;
 };
 
 struct vcnl4000_chip_spec {
@@ -342,6 +343,25 @@ static const struct vcnl4000_chip_spec vcnl4000_chip_spec_cfg[] = {
 	},
 };
 
+static ssize_t vcnl4000_read_near_level(struct iio_dev *indio_dev,
+					uintptr_t priv,
+					const struct iio_chan_spec *chan,
+					char *buf)
+{
+	struct vcnl4000_data *data = iio_priv(indio_dev);
+
+	return sprintf(buf, "%u\n", data->near_level);
+}
+
+static const struct iio_chan_spec_ext_info vcnl4000_ext_info[] = {
+	{
+		.name = "nearlevel",
+		.shared = IIO_SEPARATE,
+		.read = vcnl4000_read_near_level,
+	},
+	{ /* sentinel */ }
+};
+
 static const struct iio_chan_spec vcnl4000_channels[] = {
 	{
 		.type = IIO_LIGHT,
@@ -350,6 +370,7 @@ static const struct iio_chan_spec vcnl4000_channels[] = {
 	}, {
 		.type = IIO_PROXIMITY,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.ext_info = vcnl4000_ext_info,
 	}
 };
 
@@ -439,6 +460,10 @@ static int vcnl4000_probe(struct i2c_client *client,
 	dev_dbg(&client->dev, "%s Ambient light/proximity sensor, Rev: %02x\n",
 		data->chip_spec->prod, data->rev);
 
+	if (device_property_read_u32(&client->dev, "proximity-near-level",
+				     &data->near_level))
+		data->near_level = 0;
+
 	indio_dev->dev.parent = &client->dev;
 	indio_dev->info = &vcnl4000_info;
 	indio_dev->channels = vcnl4000_channels;