iio: light: ltr390: Add ALS channel and support for gain and resolution

Add new ALS channel and allow reading lux and scale values.
Also provide gain and resolution configuration for ALS channel.
Add automatic mode switching between the UVS and ALS channel
based on which channel is being accessed.
The default mode in which the sensor start is ALS mode.
Signed-off-by: Abhash Jha <abhashkumarjha123@gmail.com>
Link: https://patch.msgid.link/20240814113135.14575-2-abhashkumarjha123@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/light/ltr390.c

@@ -63,11 +63,17 @@
  */
 #define LTR390_WINDOW_FACTOR 1
 
+enum ltr390_mode {
+	LTR390_SET_ALS_MODE,
+	LTR390_SET_UVS_MODE,
+};
+
 struct ltr390_data {
 	struct regmap *regmap;
 	struct i2c_client *client;
 	/* Protects device from simulataneous reads */
 	struct mutex lock;
+	enum ltr390_mode mode;
 	int gain;
 	int int_time_us;
 };
@@ -95,6 +101,30 @@ static int ltr390_register_read(struct ltr390_data *data, u8 register_address)
 	return get_unaligned_le24(recieve_buffer);
 }
 
+static int ltr390_set_mode(struct ltr390_data *data, enum ltr390_mode mode)
+{
+	int ret;
+
+	if (data->mode == mode)
+		return 0;
+
+	switch (mode) {
+	case LTR390_SET_ALS_MODE:
+		ret = regmap_clear_bits(data->regmap, LTR390_MAIN_CTRL, LTR390_UVS_MODE);
+		break;
+
+	case LTR390_SET_UVS_MODE:
+		ret = regmap_set_bits(data->regmap, LTR390_MAIN_CTRL, LTR390_UVS_MODE);
+		break;
+	}
+
+	if (ret)
+		return ret;
+
+	data->mode = mode;
+	return 0;
+}
+
 static int ltr390_read_raw(struct iio_dev *iio_device,
 			   struct iio_chan_spec const *chan, int *val,
 			   int *val2, long mask)
@@ -105,15 +135,47 @@ static int ltr390_read_raw(struct iio_dev *iio_device,
 	guard(mutex)(&data->lock);
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
-		ret = ltr390_register_read(data, LTR390_UVS_DATA);
-		if (ret < 0)
-			return ret;
+		switch (chan->type) {
+		case IIO_UVINDEX:
+			ret = ltr390_set_mode(data, LTR390_SET_UVS_MODE);
+			if (ret < 0)
+				return ret;
+
+			ret = ltr390_register_read(data, LTR390_UVS_DATA);
+			if (ret < 0)
+				return ret;
+			break;
+
+		case IIO_LIGHT:
+			ret = ltr390_set_mode(data, LTR390_SET_ALS_MODE);
+			if (ret < 0)
+				return ret;
+
+			ret = ltr390_register_read(data, LTR390_ALS_DATA);
+			if (ret < 0)
+				return ret;
+			break;
+
+		default:
+			return -EINVAL;
+		}
 		*val = ret;
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
-		*val = LTR390_WINDOW_FACTOR;
-		*val2 = LTR390_COUNTS_PER_UVI;
-		return IIO_VAL_FRACTIONAL;
+		switch (chan->type) {
+		case IIO_UVINDEX:
+			*val = LTR390_WINDOW_FACTOR;
+			*val2 = LTR390_COUNTS_PER_UVI;
+			return IIO_VAL_FRACTIONAL;
+
+		case IIO_LIGHT:
+			*val = LTR390_WINDOW_FACTOR * 6 * 100;
+			*val2 = data->gain * data->int_time_us;
+			return IIO_VAL_FRACTIONAL;
+
+		default:
+			return -EINVAL;
+		}
 
 	case IIO_CHAN_INFO_INT_TIME:
 		*val = data->int_time_us;
@@ -128,11 +190,23 @@ static int ltr390_read_raw(struct iio_dev *iio_device,
 static const int ltr390_int_time_map_us[] = { 400000, 200000, 100000, 50000, 25000, 12500 };
 static const int ltr390_gain_map[] = { 1, 3, 6, 9, 18 };
 
-static const struct iio_chan_spec ltr390_channel = {
-	.type = IIO_UVINDEX,
-	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
-	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME),
-	.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_INT_TIME) | BIT(IIO_CHAN_INFO_SCALE)
+static const struct iio_chan_spec ltr390_channels[] = {
+	/* UV sensor */
+	{
+		.type = IIO_UVINDEX,
+		.scan_index = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_INT_TIME) | BIT(IIO_CHAN_INFO_SCALE)
+	},
+	/* ALS sensor */
+	{
+		.type = IIO_LIGHT,
+		.scan_index = 1,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_INT_TIME) | BIT(IIO_CHAN_INFO_SCALE)
+	},
 };
 
 static int ltr390_set_gain(struct ltr390_data *data, int val)
@@ -252,12 +326,14 @@ static int ltr390_probe(struct i2c_client *client)
 	data->int_time_us = 100000;
 	/* default value of gain from pg: 16 of the datasheet */
 	data->gain = 3;
+	/* default mode for ltr390 is ALS mode */
+	data->mode = LTR390_SET_ALS_MODE;
 
 	mutex_init(&data->lock);
 
 	indio_dev->info = &ltr390_info;
-	indio_dev->channels = &ltr390_channel;
-	indio_dev->num_channels = 1;
+	indio_dev->channels = ltr390_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ltr390_channels);
 	indio_dev->name = "ltr390";
 
 	ret = regmap_read(data->regmap, LTR390_PART_ID, &part_number);
@@ -275,8 +351,7 @@ static int ltr390_probe(struct i2c_client *client)
 	/* Wait for the registers to reset before proceeding */
 	usleep_range(1000, 2000);
 
-	ret = regmap_set_bits(data->regmap, LTR390_MAIN_CTRL,
-			      LTR390_SENSOR_ENABLE | LTR390_UVS_MODE);
+	ret = regmap_set_bits(data->regmap, LTR390_MAIN_CTRL, LTR390_SENSOR_ENABLE);
 	if (ret)
 		return dev_err_probe(dev, ret, "failed to enable the sensor\n");