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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: Vianney le Clément de Saint-Marcq <vianney.leclement@essensium.com>
Cc: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Vianney le Clément de Saint-Marcq 2015-03-30 10:35:00 +02:00 committed by Jonathan Cameron
parent 5147b21a61
commit fad65a8fe5
1 changed files with 103 additions and 3 deletions
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106
drivers/iio/temperature/mlx90614.c
View File

@ -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;