[PATCH 4/7] iio: mlx90614: Support devices with dual IR sensor

["Vianney le Clément de Saint-Marcq" <vianney.leclement@essensium.com>]

The model is detected by reading the EEPROM configuration during
probing.  In the dual IR sensor model, the ambient temperature is
exported twice to userspace.  This makes the two channels appear
completely symmetrical.

Signed-off-by: Vianney le Clément de Saint-Marcq <vianney.leclement@essensium.com>
Cc: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
---
 drivers/iio/temperature/mlx90614.c | 78 +++++++++++++++++++++++++++++++++-----
 1 file changed, 68 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/temperature/mlx90614.c b/drivers/iio/temperature/mlx90614.c
index d5b41fd..0b36746 100644
--- a/drivers/iio/temperature/mlx90614.c
+++ b/drivers/iio/temperature/mlx90614.c
@@ -60,6 +60,7 @@ static int mlx90614_read_raw(struct iio_dev *indio_dev,
 			    int *val2, long mask)
 {
 	struct mlx90614_data *data = iio_priv(indio_dev);
+	u8 cmd;
 	s32 ret;
 
 	switch (mask) {
@@ -67,20 +68,28 @@ static int mlx90614_read_raw(struct iio_dev *indio_dev,
 	case IIO_CHAN_INFO_PROCESSED:
 		switch (channel->channel2) {
 		case IIO_MOD_TEMP_AMBIENT:
-			ret = i2c_smbus_read_word_data(data->client,
-			    MLX90614_TA);
-			if (ret < 0)
-				return ret;
+			cmd = MLX90614_TA;
 			break;
 		case IIO_MOD_TEMP_OBJECT:
-			ret = i2c_smbus_read_word_data(data->client,
-			    MLX90614_TOBJ1);
-			if (ret < 0)
-				return ret;
+			switch (channel->channel) {
+			case 0:
+				cmd = MLX90614_TOBJ1;
+				break;
+			case 1:
+				cmd = MLX90614_TOBJ2;
+				break;
+			default:
+				return -EINVAL;
+			}
 			break;
 		default:
 			return -EINVAL;
 		}
+
+		ret = i2c_smbus_read_word_data(data->client, cmd);
+		if (ret < 0)
+			return ret;
+
 		switch (mask) {
 		case IIO_CHAN_INFO_RAW:
 			*val = ret;
@@ -121,6 +130,28 @@ static const struct iio_chan_spec mlx90614_channels[] = {
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
 		    BIT(IIO_CHAN_INFO_SCALE),
 	},
+	{
+		.type = IIO_TEMP,
+		.indexed = 1,
+		.modified = 1,
+		.channel = 1,
+		.channel2 = IIO_MOD_TEMP_AMBIENT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+		    BIT(IIO_CHAN_INFO_PROCESSED),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
+		    BIT(IIO_CHAN_INFO_SCALE),
+	},
+	{
+		.type = IIO_TEMP,
+		.indexed = 1,
+		.modified = 1,
+		.channel = 1,
+		.channel2 = IIO_MOD_TEMP_OBJECT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+		    BIT(IIO_CHAN_INFO_PROCESSED),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
+		    BIT(IIO_CHAN_INFO_SCALE),
+	},
 };
 
 static const struct iio_info mlx90614_info = {
@@ -128,11 +159,25 @@ static const struct iio_info mlx90614_info = {
 	.driver_module = THIS_MODULE,
 };
 
+/* Return 0 for single sensor, 1 for dual sensor, <0 on error. */
+static int mlx90614_probe_model(struct i2c_client *client)
+{
+	s32 ret;
+
+	ret = i2c_smbus_read_word_data(client, MLX90614_CONFIG);
+
+	if (ret < 0)
+		return ret;
+
+	return (ret & MLX90614_CONFIG_DUAL_MASK) ? 1 : 0;
+}
+
 static int mlx90614_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
 	struct iio_dev *indio_dev;
 	struct mlx90614_data *data;
+	int ret;
 
 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
 		return -ENODEV;
@@ -150,8 +195,21 @@ static int mlx90614_probe(struct i2c_client *client,
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->info = &mlx90614_info;
 
-	indio_dev->channels = mlx90614_channels;
-	indio_dev->num_channels = ARRAY_SIZE(mlx90614_channels);
+	ret = mlx90614_probe_model(client);
+	switch (ret) {
+	case 0:
+		dev_dbg(&client->dev, "Found single sensor");
+		indio_dev->channels = mlx90614_channels;
+		indio_dev->num_channels = 2;
+		break;
+	case 1:
+		dev_dbg(&client->dev, "Found dual sensor");
+		indio_dev->channels = mlx90614_channels;
+		indio_dev->num_channels = 4;
+		break;
+	default:
+		return ret;
+	}
 
 	return iio_device_register(indio_dev);
 }
-- 
2.3.0