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/*
* mpl115.c - Support for Freescale MPL115A pressure/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.
*
* TODO: shutdown pin
*
*/
#include <linux/module.h>
#include <linux/iio/iio.h>
#include <linux/delay.h>
#include "mpl115.h"
#define MPL115_PADC 0x00 /* pressure ADC output value, MSB first, 10 bit */
#define MPL115_TADC 0x02 /* temperature ADC output value, MSB first, 10 bit */
#define MPL115_A0 0x04 /* 12 bit integer, 3 bit fraction */
#define MPL115_B1 0x06 /* 2 bit integer, 13 bit fraction */
#define MPL115_B2 0x08 /* 1 bit integer, 14 bit fraction */
#define MPL115_C12 0x0a /* 0 bit integer, 13 bit fraction */
#define MPL115_CONVERT 0x12 /* convert temperature and pressure */
struct mpl115_data {
struct device *dev;
struct mutex lock;
s16 a0;
s16 b1, b2;
s16 c12;
const struct mpl115_ops *ops;
};
static int mpl115_request(struct mpl115_data *data)
{
int ret = data->ops->write(data->dev, MPL115_CONVERT, 0);
if (ret < 0)
return ret;
usleep_range(3000, 4000);
return 0;
}
static int mpl115_comp_pressure(struct mpl115_data *data, int *val, int *val2)
{
int ret;
u16 padc, tadc;
int a1, y1, pcomp;
unsigned kpa;
mutex_lock(&data->lock);
ret = mpl115_request(data);
if (ret < 0)
goto done;
ret = data->ops->read(data->dev, MPL115_PADC);
if (ret < 0)
goto done;
padc = ret >> 6;
ret = data->ops->read(data->dev, MPL115_TADC);
if (ret < 0)
goto done;
tadc = ret >> 6;
/* see Freescale AN3785 */
a1 = data->b1 + ((data->c12 * tadc) >> 11);
y1 = (data->a0 << 10) + a1 * padc;
/* compensated pressure with 4 fractional bits */
pcomp = (y1 + ((data->b2 * (int) tadc) >> 1)) >> 9;
kpa = pcomp * (115 - 50) / 1023 + (50 << 4);
*val = kpa >> 4;
*val2 = (kpa & 15) * (1000000 >> 4);
done:
mutex_unlock(&data->lock);
return ret;
}
static int mpl115_read_temp(struct mpl115_data *data)
{
int ret;
mutex_lock(&data->lock);
ret = mpl115_request(data);
if (ret < 0)
goto done;
ret = data->ops->read(data->dev, MPL115_TADC);
done:
mutex_unlock(&data->lock);
return ret;
}
static int mpl115_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct mpl115_data *data = iio_priv(indio_dev);
int ret;
switch (mask) {
case IIO_CHAN_INFO_PROCESSED:
ret = mpl115_comp_pressure(data, val, val2);
if (ret < 0)
return ret;
return IIO_VAL_INT_PLUS_MICRO;
case IIO_CHAN_INFO_RAW:
/* temperature -5.35 C / LSB, 472 LSB is 25 C */
ret = mpl115_read_temp(data);
if (ret < 0)
return ret;
*val = ret >> 6;
return IIO_VAL_INT;
case IIO_CHAN_INFO_OFFSET:
*val = -605;
*val2 = 750000;
return IIO_VAL_INT_PLUS_MICRO;
case IIO_CHAN_INFO_SCALE:
*val = -186;
*val2 = 915888;
return IIO_VAL_INT_PLUS_MICRO;
}
return -EINVAL;
}
static const struct iio_chan_spec mpl115_channels[] = {
{
.type = IIO_PRESSURE,
.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
},
{
.type = IIO_TEMP,
.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 mpl115_info = {
.read_raw = &mpl115_read_raw,
.driver_module = THIS_MODULE,
};
int mpl115_probe(struct device *dev, const char *name,
const struct mpl115_ops *ops)
{
struct mpl115_data *data;
struct iio_dev *indio_dev;
int ret;
indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
if (!indio_dev)
return -ENOMEM;
data = iio_priv(indio_dev);
data->dev = dev;
data->ops = ops;
mutex_init(&data->lock);
indio_dev->info = &mpl115_info;
indio_dev->name = name;
indio_dev->dev.parent = dev;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = mpl115_channels;
indio_dev->num_channels = ARRAY_SIZE(mpl115_channels);
ret = data->ops->init(data->dev);
if (ret)
return ret;
ret = data->ops->read(data->dev, MPL115_A0);
if (ret < 0)
return ret;
data->a0 = ret;
ret = data->ops->read(data->dev, MPL115_B1);
if (ret < 0)
return ret;
data->b1 = ret;
ret = data->ops->read(data->dev, MPL115_B2);
if (ret < 0)
return ret;
data->b2 = ret;
ret = data->ops->read(data->dev, MPL115_C12);
if (ret < 0)
return ret;
data->c12 = ret;
return devm_iio_device_register(dev, indio_dev);
}
EXPORT_SYMBOL_GPL(mpl115_probe);
MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
MODULE_DESCRIPTION("Freescale MPL115 pressure/temperature driver");
MODULE_LICENSE("GPL");
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