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194 lines
4.3 KiB
194 lines
4.3 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* mpl115.c - Support for Freescale MPL115A pressure/temperature sensor |
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* |
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* Copyright (c) 2014 Peter Meerwald <[email protected]> |
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* |
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* TODO: shutdown pin |
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*/ |
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#include <linux/module.h> |
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#include <linux/iio/iio.h> |
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#include <linux/delay.h> |
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#include "mpl115.h" |
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#define MPL115_PADC 0x00 /* pressure ADC output value, MSB first, 10 bit */ |
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#define MPL115_TADC 0x02 /* temperature ADC output value, MSB first, 10 bit */ |
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#define MPL115_A0 0x04 /* 12 bit integer, 3 bit fraction */ |
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#define MPL115_B1 0x06 /* 2 bit integer, 13 bit fraction */ |
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#define MPL115_B2 0x08 /* 1 bit integer, 14 bit fraction */ |
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#define MPL115_C12 0x0a /* 0 bit integer, 13 bit fraction */ |
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#define MPL115_CONVERT 0x12 /* convert temperature and pressure */ |
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struct mpl115_data { |
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struct device *dev; |
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struct mutex lock; |
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s16 a0; |
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s16 b1, b2; |
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s16 c12; |
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const struct mpl115_ops *ops; |
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}; |
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static int mpl115_request(struct mpl115_data *data) |
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{ |
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int ret = data->ops->write(data->dev, MPL115_CONVERT, 0); |
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if (ret < 0) |
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return ret; |
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usleep_range(3000, 4000); |
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return 0; |
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} |
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static int mpl115_comp_pressure(struct mpl115_data *data, int *val, int *val2) |
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{ |
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int ret; |
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u16 padc, tadc; |
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int a1, y1, pcomp; |
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unsigned kpa; |
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mutex_lock(&data->lock); |
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ret = mpl115_request(data); |
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if (ret < 0) |
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goto done; |
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ret = data->ops->read(data->dev, MPL115_PADC); |
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if (ret < 0) |
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goto done; |
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padc = ret >> 6; |
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ret = data->ops->read(data->dev, MPL115_TADC); |
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if (ret < 0) |
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goto done; |
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tadc = ret >> 6; |
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/* see Freescale AN3785 */ |
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a1 = data->b1 + ((data->c12 * tadc) >> 11); |
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y1 = (data->a0 << 10) + a1 * padc; |
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/* compensated pressure with 4 fractional bits */ |
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pcomp = (y1 + ((data->b2 * (int) tadc) >> 1)) >> 9; |
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kpa = pcomp * (115 - 50) / 1023 + (50 << 4); |
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*val = kpa >> 4; |
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*val2 = (kpa & 15) * (1000000 >> 4); |
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done: |
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mutex_unlock(&data->lock); |
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return ret; |
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} |
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static int mpl115_read_temp(struct mpl115_data *data) |
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{ |
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int ret; |
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mutex_lock(&data->lock); |
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ret = mpl115_request(data); |
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if (ret < 0) |
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goto done; |
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ret = data->ops->read(data->dev, MPL115_TADC); |
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done: |
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mutex_unlock(&data->lock); |
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return ret; |
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} |
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static int mpl115_read_raw(struct iio_dev *indio_dev, |
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struct iio_chan_spec const *chan, |
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int *val, int *val2, long mask) |
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{ |
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struct mpl115_data *data = iio_priv(indio_dev); |
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int ret; |
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switch (mask) { |
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case IIO_CHAN_INFO_PROCESSED: |
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ret = mpl115_comp_pressure(data, val, val2); |
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if (ret < 0) |
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return ret; |
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return IIO_VAL_INT_PLUS_MICRO; |
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case IIO_CHAN_INFO_RAW: |
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/* temperature -5.35 C / LSB, 472 LSB is 25 C */ |
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ret = mpl115_read_temp(data); |
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if (ret < 0) |
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return ret; |
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*val = ret >> 6; |
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return IIO_VAL_INT; |
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case IIO_CHAN_INFO_OFFSET: |
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*val = -605; |
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*val2 = 750000; |
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return IIO_VAL_INT_PLUS_MICRO; |
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case IIO_CHAN_INFO_SCALE: |
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*val = -186; |
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*val2 = 915888; |
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return IIO_VAL_INT_PLUS_MICRO; |
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} |
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return -EINVAL; |
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} |
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static const struct iio_chan_spec mpl115_channels[] = { |
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{ |
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.type = IIO_PRESSURE, |
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.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), |
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}, |
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{ |
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.type = IIO_TEMP, |
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), |
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.info_mask_shared_by_type = |
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BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_SCALE), |
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}, |
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}; |
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static const struct iio_info mpl115_info = { |
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.read_raw = &mpl115_read_raw, |
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}; |
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int mpl115_probe(struct device *dev, const char *name, |
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const struct mpl115_ops *ops) |
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{ |
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struct mpl115_data *data; |
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struct iio_dev *indio_dev; |
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int ret; |
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indio_dev = devm_iio_device_alloc(dev, sizeof(*data)); |
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if (!indio_dev) |
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return -ENOMEM; |
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data = iio_priv(indio_dev); |
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data->dev = dev; |
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data->ops = ops; |
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mutex_init(&data->lock); |
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indio_dev->info = &mpl115_info; |
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indio_dev->name = name; |
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indio_dev->modes = INDIO_DIRECT_MODE; |
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indio_dev->channels = mpl115_channels; |
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indio_dev->num_channels = ARRAY_SIZE(mpl115_channels); |
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ret = data->ops->init(data->dev); |
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if (ret) |
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return ret; |
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ret = data->ops->read(data->dev, MPL115_A0); |
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if (ret < 0) |
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return ret; |
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data->a0 = ret; |
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ret = data->ops->read(data->dev, MPL115_B1); |
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if (ret < 0) |
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return ret; |
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data->b1 = ret; |
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ret = data->ops->read(data->dev, MPL115_B2); |
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if (ret < 0) |
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return ret; |
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data->b2 = ret; |
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ret = data->ops->read(data->dev, MPL115_C12); |
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if (ret < 0) |
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return ret; |
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data->c12 = ret; |
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return devm_iio_device_register(dev, indio_dev); |
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} |
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EXPORT_SYMBOL_GPL(mpl115_probe); |
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MODULE_AUTHOR("Peter Meerwald <[email protected]>"); |
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MODULE_DESCRIPTION("Freescale MPL115 pressure/temperature driver"); |
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MODULE_LICENSE("GPL");
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