diff options
Diffstat (limited to 'drivers/iio/pressure/mpl115.c')
| -rw-r--r-- | drivers/iio/pressure/mpl115.c | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/drivers/iio/pressure/mpl115.c b/drivers/iio/pressure/mpl115.c new file mode 100644 index 000000000..ab4786d01 --- /dev/null +++ b/drivers/iio/pressure/mpl115.c @@ -0,0 +1,199 @@ +/* + * 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"); |