iio: Add Melexis mlx90614 contact-less infrared temperature sensor driver

I2C-controlled sensor measures ambient and object temperatuer

see
http://www.melexis.com/Infrared-Thermometer-Sensors/Infrared-Thermometer-Sensors/MLX90614-615.aspxSigned-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/temperature/Kconfig

@@ -3,6 +3,16 @@
 #
 menu "Temperature sensors"
 
+config MLX90614
+	tristate "MLX90614 contact-less infrared sensor"
+	depends on I2C
+	help
+	  If you say yes here you get support for the Melexis
+	  MLX90614 contact-less infrared sensor connected with I2C.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called mlx90614.
+
 config TMP006
 	tristate "TMP006 infrared thermopile sensor"
 	depends on I2C

drivers/iio/temperature/Makefile

@@ -2,4 +2,5 @@
 # Makefile for industrial I/O temperature drivers
 #
 
+obj-$(CONFIG_MLX90614) += mlx90614.o
 obj-$(CONFIG_TMP006) += tmp006.o

drivers/iio/temperature/mlx90614.c

+/*
+ * mlx90614.c - Support for Melexis MLX90614 contactless IR temperature sensor
+ *
+ * Copyright (c) 2014 Peter Meerwald <pmeerw@pmeerw.net>
+ *
+ * This file is subject to the terms and conditions of version 2 of
+ * the GNU General Public License.  See the file COPYING in the main
+ * directory of this archive for more details.
+ *
+ * Driver for the Melexis MLX90614 I2C 16-bit IR thermopile sensor
+ *
+ * (7-bit I2C slave address 0x5a, 100KHz bus speed only!)
+ *
+ * TODO: sleep mode, configuration EEPROM
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+
+#include <linux/iio/iio.h>
+
+#define MLX90614_OP_RAM 0x00
+
+/* RAM offsets with 16-bit data, MSB first */
+#define MLX90614_TA 0x06 /* ambient temperature */
+#define MLX90614_TOBJ1 0x07 /* object temperature */
+
+struct mlx90614_data {
+	struct i2c_client *client;
+};
+
+static int mlx90614_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *channel, int *val,
+			    int *val2, long mask)
+{
+	struct mlx90614_data *data = iio_priv(indio_dev);
+	s32 ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW: /* 0.02K / LSB */
+		switch (channel->channel2) {
+		case IIO_MOD_TEMP_AMBIENT:
+			ret = i2c_smbus_read_word_data(data->client,
+			    MLX90614_OP_RAM | MLX90614_TA);
+			if (ret < 0)
+				return ret;
+			break;
+		case IIO_MOD_TEMP_OBJECT:
+			ret = i2c_smbus_read_word_data(data->client,
+			    MLX90614_OP_RAM | MLX90614_TOBJ1);
+			if (ret < 0)
+				return ret;
+			break;
+		default:
+			return -EINVAL;
+		}
+		*val = ret;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_OFFSET:
+		*val = 13657;
+		*val2 = 500000;
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 20;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_chan_spec mlx90614_channels[] = {
+	{
+		.type = IIO_TEMP,
+		.modified = 1,
+		.channel2 = IIO_MOD_TEMP_AMBIENT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
+		    BIT(IIO_CHAN_INFO_SCALE),
+	},
+	{
+		.type = IIO_TEMP,
+		.modified = 1,
+		.channel2 = IIO_MOD_TEMP_OBJECT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
+		    BIT(IIO_CHAN_INFO_SCALE),
+	},
+};
+
+static const struct iio_info mlx90614_info = {
+	.read_raw = mlx90614_read_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static int mlx90614_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct iio_dev *indio_dev;
+	struct mlx90614_data *data;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
+		return -ENODEV;
+
+	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;
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->name = id->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &mlx90614_info;
+
+	indio_dev->channels = mlx90614_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mlx90614_channels);
+
+	return iio_device_register(indio_dev);
+}
+
+static int mlx90614_remove(struct i2c_client *client)
+{
+	iio_device_unregister(i2c_get_clientdata(client));
+
+	return 0;
+}
+
+static const struct i2c_device_id mlx90614_id[] = {
+	{ "mlx90614", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, mlx90614_id);
+
+static struct i2c_driver mlx90614_driver = {
+	.driver = {
+		.name	= "mlx90614",
+		.owner	= THIS_MODULE,
+	},
+	.probe = mlx90614_probe,
+	.remove = mlx90614_remove,
+	.id_table = mlx90614_id,
+};
+module_i2c_driver(mlx90614_driver);
+
+MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
+MODULE_DESCRIPTION("Melexis MLX90614 contactless IR temperature sensor driver");
+MODULE_LICENSE("GPL");