/*
 * 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");