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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 | /* * 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), 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"); |