200 lines
4.5 KiB
C
200 lines
4.5 KiB
C
/*
|
|
* 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,
|
|
};
|
|
|
|
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");
|