Add support for UPISEMI us5182d als and proximity sensor.
Supports raw readings.
Data sheet for this device can be found here:
http://www.upi-semi.com/temp/uS5182D-DS-P0103-temp.pdf

nitpicking below
 

threshold

+ * roughly between 12-32 lux
+ */
+static u16 us5182d_dark_ths_vals[] = {170, 200, 512, 512, 800, 2000, 4000,
+				      8000};
+
+enum mode {
+	US5182D_ALS_PX,
+	US5182D_ALS_ONLY,
+	US5182D_PX_ONLY
+};
+
+struct us5182d_data {
+	struct i2c_client *client;
+	struct mutex lock;
+
+	/* Glass attenuation factor */
+	u32 ga;
+
+	/* Dark gain tuning */
+	u8 lower_dark_gain;
+	u8 upper_dark_gain;
+	u16 *us5182d_dark_ths;
+
+	u8 opmode;
+};
+
+static IIO_CONST_ATTR(in_illuminance_scale_available,
+		      "0.0021 0.0039 0.0076 0.0196 0.0336 0.061 0.1078 0.1885");
+
+static struct attribute *us5182d_attrs[] = {
+	&iio_const_attr_in_illuminance_scale_available.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group us5182d_attr_group = {
+	.attrs = us5182d_attrs,
+};
+
+static const struct {
+	u8 reg;
+	u8 val;
+} us5182d_regvals[] = {
+	{US5182D_REG_CFG0, (US5182D_CFG0_SHUTDOWN_EN |
+			    US5182D_CFG0_WORD_ENABLE)},
+	{US5182D_REG_CFG1, US5182D_CFG1_ALS_RES16},
+	{US5182D_REG_CFG2, (US5182D_CFG2_PX_RES16 |
+			    US5182D_CFG2_PXGAIN_DEFAULT)},
+	{US5182D_REG_CFG3, US5182D_CFG3_LED_CURRENT100},
+	{US5182D_REG_MODE_STORE, US5182D_STORE_MODE},
+	{US5182D_REG_CFG4, 0x00},
+};
+
+static const struct iio_chan_spec us5182d_channels[] = {
+	{
+		.type = IIO_LIGHT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+	},
+	{
+		.type = IIO_PROXIMITY,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+	}
+};
+
+static int us5182d_get_als(struct us5182d_data *data)
+{
+	int ret;
+	unsigned long result;
+
+	ret = i2c_smbus_read_word_data(data->client,
+				       US5182D_REG_ADL);
+	if (ret < 0)
+		return ret;
+
+	result = ret * data->ga / US5182D_GA_RESOLUTION;
+	if (result > 0xffff)
+		result = 0xffff;
+
+	return result;
+}
+
+static int us5182d_set_opmode(struct us5182d_data *data, u8 mode)
+{
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(data->client, US5182D_REG_CFG0);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * In oneshot mode the chip will power itself down after taking the
+	 * required measurement.
+	 */
+	ret = ret | US5182D_CFG0_ONESHOT_EN;
+
+	/* update mode */
+	ret = ret & ~US5182D_OPMODE_MASK;
+	ret = ret | (mode << US5182D_OPMODE_SHIFT);
+
+	/*
+	 * After updating the operating mode, the chip requires that
+	 * the operation is stored, by writing 1 in the STORE_MODE
+	 * register (auto-clearing).
+	 */
+	ret = i2c_smbus_write_byte_data(data->client, US5182D_REG_CFG0, ret);
+	if (ret < 0)
+		return ret;
+
+	if (mode == data->opmode)
+		return 0;
+
+	ret = i2c_smbus_write_byte_data(data->client, US5182D_REG_MODE_STORE,
+					US5182D_STORE_MODE);
+	if (ret < 0)
+		return ret;
+
+	data->opmode = mode;
+	msleep(US5182D_OPSTORE_SLEEP_TIME);
+
+	return 0;
+}
+
+static int us5182d_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int *val,
+			    int *val2, long mask)
+{
+	struct us5182d_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		switch (chan->type) {
+		case IIO_LIGHT:
+			mutex_lock(&data->lock);
+			ret = us5182d_set_opmode(data, US5182D_OPMODE_ALS);
+			if (ret < 0)
+				goto out_err;
+
+			ret = us5182d_get_als(data);
+			if (ret < 0)
+				goto out_err;
+			mutex_unlock(&data->lock);
+			*val = ret;
+			return IIO_VAL_INT;
+		case IIO_PROXIMITY:
+			mutex_lock(&data->lock);
+			ret = us5182d_set_opmode(data, US5182D_OPMODE_PX);
+			if (ret < 0)
+				goto out_err;
+
+			ret = i2c_smbus_read_word_data(data->client,
+						       US5182D_REG_PDL);
+			if (ret < 0)
+				goto out_err;
+			mutex_unlock(&data->lock);
+			*val = ret;
+			return  IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+
+	case IIO_CHAN_INFO_SCALE:
+		ret = i2c_smbus_read_byte_data(data->client, US5182D_REG_CFG1);
+		if (ret < 0)
+			return ret;
+
+		*val = 0;
+		*val2 = us5182d_scales[ret & US5182D_AGAIN_MASK];
+
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+
+	return -EINVAL;
+out_err:
+	mutex_unlock(&data->lock);
+	return ret;
+}
+
+/**`

there is an extra character (`) to remove

+ * us5182d_update_dark_th - update Darh_Th registers
+ * @data	us5182d_data structure
+ * @index	index in us5182d_dark_ths array to use for the updated value
+ *
+ * Function needs to be called with a lock held because it needs two i2c write
+ * byte operations as these registers (0x27 0x28) don't work in word mode
+ * accessing.
+ */
+static int us5182d_update_dark_th(struct us5182d_data *data, int index)
+{
+	__be16 dark_th = cpu_to_be16(data->us5182d_dark_ths[index]);
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(data->client, US5182D_REG_UDARK_TH,
+					((u8 *)&dark_th)[0]);
+	if (ret < 0)
+		return ret;
+
+	return i2c_smbus_write_byte_data(data->client, US5182D_REG_UDARK_TH + 1,
+					((u8 *)&dark_th)[1]);
+}
+
+/**`
+ * us5182d_apply_scale - update the ALS scale
+ * @data	us5182d_data structure
+ * @index	index in us5182d_scales array to use for the updated value
+ *
+ * Function needs to be called with a lock held as we're having more than one
+ * i2c operations.

operation

+ */
+static int us5182d_apply_scale(struct us5182d_data *data, int index)
+{
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(data->client, US5182D_REG_CFG1);
+	if (ret < 0)
+		return ret;
+
+	ret = ret & (~US5182D_AGAIN_MASK);
+	ret |= index;
+
+	ret = i2c_smbus_write_byte_data(data->client, US5182D_REG_CFG1, ret);
+	if (ret < 0)
+		return ret;
+
+	return us5182d_update_dark_th(data, index);
+}
+
+static int us5182d_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int val,
+			     int val2, long mask)
+{
+	struct us5182d_data *data = iio_priv(indio_dev);
+	int ret, i;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		if (val != 0)
+			return -EINVAL;
+		for (i = 0; i < ARRAY_SIZE(us5182d_scales); i++)
+			if (val2 == us5182d_scales[i]) {
+				mutex_lock(&data->lock);
+				ret = us5182d_apply_scale(data, i);
+				mutex_unlock(&data->lock);
+				return ret;
+			}
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_info us5182d_info = {
+	.driver_module	= THIS_MODULE,
+	.read_raw = us5182d_read_raw,
+	.write_raw = us5182d_write_raw,
+	.attrs = &us5182d_attr_group,
+};
+
+static int us5182d_reset(struct iio_dev *indio_dev)
+{
+	struct us5182d_data *data = iio_priv(indio_dev);
+
+	return i2c_smbus_write_byte_data(data->client, US5182D_REG_CFG3,
+					 US5182D_RESET_CHIP);
+}
+
+static int us5182d_init(struct iio_dev *indio_dev)
+{
+	struct us5182d_data *data = iio_priv(indio_dev);
+	int i, ret;
+
+	ret = us5182d_reset(indio_dev);
+	if (ret < 0)
+		return ret;
+
+	data->opmode = 0;
+	for (i = 0; i < ARRAY_SIZE(us5182d_regvals); i++) {
+		ret = i2c_smbus_write_byte_data(data->client,
+						us5182d_regvals[i].reg,
+						us5182d_regvals[i].val);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+static void us5182d_get_platform_data(struct iio_dev *indio_dev)
+{
+	struct us5182d_data *data = iio_priv(indio_dev);
+
+	if (device_property_read_u32(&data->client->dev, "upisemi,glass-coef",
+				     &data->ga))
+		data->ga = US5182D_GA_RESOLUTION;
+	if (device_property_read_u16_array(&data->client->dev,
+					   "upisemi,dark-ths",
+					   data->us5182d_dark_ths,
+					   ARRAY_SIZE(us5182d_dark_ths_vals)))
+		data->us5182d_dark_ths = us5182d_dark_ths_vals;
+	if (device_property_read_u8(&data->client->dev,
+				    "upisemi,upper-dark-gain",
+				    &data->upper_dark_gain))
+		data->upper_dark_gain = US5182D_REG_AUTO_HDARK_GAIN_DEFAULT;
+	if (device_property_read_u8(&data->client->dev,
+				    "upisemi,lower-dark-gain",
+				    &data->lower_dark_gain))
+		data->lower_dark_gain = US5182D_REG_AUTO_LDARK_GAIN_DEFAULT;
+}
+
+static int  us5182d_dark_gain_config(struct iio_dev *indio_dev)
+{
+	struct us5182d_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = us5182d_update_dark_th(data, US5182D_CFG1_AGAIN_DEFAULT);
+	if (ret < 0)
+		return ret;
+
+	ret = i2c_smbus_write_byte_data(data->client,
+					US5182D_REG_AUTO_LDARK_GAIN,
+					data->lower_dark_gain);
+	if (ret < 0)
+		return ret;
+
+	ret = i2c_smbus_write_byte_data(data->client,
+					US5182D_REG_AUTO_HDARK_GAIN,
+					data->upper_dark_gain);
+	if (ret < 0)
+		return ret;
+
+	return i2c_smbus_write_byte_data(data->client, US5182D_REG_DARK_AUTO_EN,
+					 US5182D_REG_DARK_AUTO_EN_DEFAULT);
+}
+
+static int us5182d_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct us5182d_data *data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+
+	mutex_init(&data->lock);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &us5182d_info;
+	indio_dev->name = US5182D_DRV_NAME;
+	indio_dev->channels = us5182d_channels;
+	indio_dev->num_channels = ARRAY_SIZE(us5182d_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = i2c_smbus_read_byte_data(data->client, US5182D_REG_CHIPID);
+	if (ret != US5182D_CHIPID) {
+		dev_err(&data->client->dev,
+			"Failed to detect US5182 light chip\n");
+		return (ret < 0) ? ret : -ENODEV;
+	}
+
+	us5182d_get_platform_data(indio_dev);
+	ret = us5182d_init(indio_dev);
+	if (ret < 0)
+		return ret;
+
+	ret = us5182d_dark_gain_config(indio_dev);
+	if (ret < 0)
+		return ret;
+
+	return iio_device_register(indio_dev);
+}
+
+static int us5182d_remove(struct i2c_client *client)
+{
+	iio_device_unregister(i2c_get_clientdata(client));
+	return i2c_smbus_write_byte_data(client, US5182D_REG_CFG0,
+					 US5182D_CFG0_SHUTDOWN_EN);
+}
+
+static const struct acpi_device_id us5182d_acpi_match[] = {
+	{ "USD5182", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(acpi, us5182d_acpi_match);
+
+static const struct i2c_device_id us5182d_id[] = {
+		{"usd5182", 0},
+		{}
+};
+
+MODULE_DEVICE_TABLE(i2c, us5182d_id);
+
+static struct i2c_driver us5182d_driver = {
+	.driver = {
+		.name = US5182D_DRV_NAME,
+		.acpi_match_table = ACPI_PTR(us5182d_acpi_match),
+	},
+	.probe = us5182d_probe,
+	.remove = us5182d_remove,
+	.id_table = us5182d_id,
+
+};
+module_i2c_driver(us5182d_driver);
+
+MODULE_AUTHOR("Adriana Reus [off-list ref]");
+MODULE_DESCRIPTION("Driver for us5182d Proximity and Light Sensor");
+MODULE_LICENSE("GPL v2");

-- 

Peter Meerwald
+43-664-2444418 (mobile)