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Commit fad65a8f authored by Vianney le Clément de Saint-Marcq's avatar Vianney le Clément de Saint-Marcq Committed by Jonathan Cameron
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iio: mlx90614: Add emissivity setting 



The mapping from the 16-bit EEPROM value to the decimal 0-1 range is
approximate.  A special case ensures 0xFFFF shows as 1.0 instead of
0.999998565.

Writing to EEPROM requires an explicit erase by writing zero.  In
addition, it takes 20ms for the erase/write to complete.  During this
time no EEPROM register should be accessed.  Therefore, two msleep()s
are added to the write function and a mutex protects against concurrent
access.

Signed-off-by: default avatarVianney le Clément de Saint-Marcq <vianney.leclement@essensium.com>
Cc: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent 5147b21a

drivers/iio/temperature/mlx90614.c

+103 −3
Original line number Diff line number Diff line
@@ -12,12 +12,13 @@ 
 *

 * (7-bit I2C slave address 0x5a, 100KHz bus speed only!)

 *

 * TODO: sleep mode, configuration EEPROM

 * TODO: sleep mode, filter configuration

 */



#include <linux/err.h>

#include <linux/i2c.h>

#include <linux/module.h>

#include <linux/delay.h>



#include <linux/iio/iio.h>
@@ -53,8 +54,47 @@ 


struct mlx90614_data {

	struct i2c_client *client;

	struct mutex lock; /* for EEPROM access only */

};



/*

 * Erase an address and write word.

 * The mutex must be locked before calling.

 */

static s32 mlx90614_write_word(const struct i2c_client *client, u8 command,

			       u16 value)

{

	/*

	 * Note: The mlx90614 requires a PEC on writing but does not send us a

	 * valid PEC on reading.  Hence, we cannot set I2C_CLIENT_PEC in

	 * i2c_client.flags.  As a workaround, we use i2c_smbus_xfer here.

	 */

	union i2c_smbus_data data;

	s32 ret;



	dev_dbg(&client->dev, "Writing 0x%x to address 0x%x", value, command);



	data.word = 0x0000; /* erase command */

	ret = i2c_smbus_xfer(client->adapter, client->addr,

			     client->flags | I2C_CLIENT_PEC,

			     I2C_SMBUS_WRITE, command,

			     I2C_SMBUS_WORD_DATA, &data);

	if (ret < 0)

		return ret;



	msleep(MLX90614_TIMING_EEPROM);



	data.word = value; /* actual write */

	ret = i2c_smbus_xfer(client->adapter, client->addr,

			     client->flags | I2C_CLIENT_PEC,

			     I2C_SMBUS_WRITE, command,

			     I2C_SMBUS_WORD_DATA, &data);



	msleep(MLX90614_TIMING_EEPROM);



	return ret;

}



static int mlx90614_read_raw(struct iio_dev *indio_dev,

			    struct iio_chan_spec const *channel, int *val,

			    int *val2, long mask)
@@ -97,6 +137,61 @@ static int mlx90614_read_raw(struct iio_dev *indio_dev, 
	case IIO_CHAN_INFO_SCALE:

		*val = 20;

		return IIO_VAL_INT;

	case IIO_CHAN_INFO_CALIBEMISSIVITY: /* 1/65535 / LSB */

		mutex_lock(&data->lock);

		ret = i2c_smbus_read_word_data(data->client,

					       MLX90614_EMISSIVITY);

		mutex_unlock(&data->lock);



		if (ret < 0)

			return ret;



		if (ret == 65535) {

			*val = 1;

			*val2 = 0;

		} else {

			*val = 0;

			*val2 = ret * 15259; /* 1/65535 ~ 0.000015259 */

		}

		return IIO_VAL_INT_PLUS_NANO;

	default:

		return -EINVAL;

	}

}



static int mlx90614_write_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_CALIBEMISSIVITY: /* 1/65535 / LSB */

		if (val < 0 || val2 < 0 || val > 1 || (val == 1 && val2 != 0))

			return -EINVAL;

		val = val * 65535 + val2 / 15259; /* 1/65535 ~ 0.000015259 */



		mutex_lock(&data->lock);

		ret = mlx90614_write_word(data->client, MLX90614_EMISSIVITY,

					  val);

		mutex_unlock(&data->lock);



		if (ret < 0)

			return ret;

		return 0;

	default:

		return -EINVAL;

	}

}



static int mlx90614_write_raw_get_fmt(struct iio_dev *indio_dev,

				     const struct iio_chan_spec const *channel,

				     long mask)

{

	switch (mask) {

	case IIO_CHAN_INFO_CALIBEMISSIVITY:

		return IIO_VAL_INT_PLUS_NANO;

	default:

		return -EINVAL;

	}
@@ -115,7 +210,8 @@ static const struct iio_chan_spec mlx90614_channels[] = { 
		.type = IIO_TEMP,

		.modified = 1,

		.channel2 = IIO_MOD_TEMP_OBJECT,

		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),

		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |

		    BIT(IIO_CHAN_INFO_CALIBEMISSIVITY),

		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |

		    BIT(IIO_CHAN_INFO_SCALE),

	},
@@ -125,7 +221,8 @@ static const struct iio_chan_spec mlx90614_channels[] = { 
		.modified = 1,

		.channel = 1,

		.channel2 = IIO_MOD_TEMP_OBJECT,

		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),

		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |

		    BIT(IIO_CHAN_INFO_CALIBEMISSIVITY),

		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |

		    BIT(IIO_CHAN_INFO_SCALE),

	},
@@ -133,6 +230,8 @@ static const struct iio_chan_spec mlx90614_channels[] = { 


static const struct iio_info mlx90614_info = {

	.read_raw = mlx90614_read_raw,

	.write_raw = mlx90614_write_raw,

	.write_raw_get_fmt = mlx90614_write_raw_get_fmt,

	.driver_module = THIS_MODULE,

};
@@ -166,6 +265,7 @@ static int mlx90614_probe(struct i2c_client *client, 
	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->name = id->name;