diff options
Diffstat (limited to 'drivers/iio/pressure/ms5611_core.c')
| -rw-r--r-- | drivers/iio/pressure/ms5611_core.c | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/drivers/iio/pressure/ms5611_core.c b/drivers/iio/pressure/ms5611_core.c new file mode 100644 index 000000000000..e42c8531d9b3 --- /dev/null +++ b/drivers/iio/pressure/ms5611_core.c @@ -0,0 +1,215 @@ +/* + * MS5611 pressure and temperature sensor driver + * + * Copyright (c) Tomasz Duszynski <tduszyns@gmail.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * Data sheet: + * http://www.meas-spec.com/downloads/MS5611-01BA03.pdf + * + */ + +#include <linux/module.h> +#include <linux/iio/iio.h> +#include <linux/delay.h> + +#include "ms5611.h" + +static bool ms5611_prom_is_valid(u16 *prom, size_t len) +{ + int i, j; + uint16_t crc = 0, crc_orig = prom[7] & 0x000F; + + prom[7] &= 0xFF00; + + for (i = 0; i < len * 2; i++) { + if (i % 2 == 1) + crc ^= prom[i >> 1] & 0x00FF; + else + crc ^= prom[i >> 1] >> 8; + + for (j = 0; j < 8; j++) { + if (crc & 0x8000) + crc = (crc << 1) ^ 0x3000; + else + crc <<= 1; + } + } + + crc = (crc >> 12) & 0x000F; + + return crc_orig != 0x0000 && crc == crc_orig; +} + +static int ms5611_read_prom(struct iio_dev *indio_dev) +{ + int ret, i; + struct ms5611_state *st = iio_priv(indio_dev); + + for (i = 0; i < MS5611_PROM_WORDS_NB; i++) { + ret = st->read_prom_word(&indio_dev->dev, i, &st->prom[i]); + if (ret < 0) { + dev_err(&indio_dev->dev, + "failed to read prom at %d\n", i); + return ret; + } + } + + if (!ms5611_prom_is_valid(st->prom, MS5611_PROM_WORDS_NB)) { + dev_err(&indio_dev->dev, "PROM integrity check failed\n"); + return -ENODEV; + } + + return 0; +} + +static int ms5611_read_temp_and_pressure(struct iio_dev *indio_dev, + s32 *temp, s32 *pressure) +{ + int ret; + s32 t, p; + s64 off, sens, dt; + struct ms5611_state *st = iio_priv(indio_dev); + + ret = st->read_adc_temp_and_pressure(&indio_dev->dev, &t, &p); + if (ret < 0) { + dev_err(&indio_dev->dev, + "failed to read temperature and pressure\n"); + return ret; + } + + dt = t - (st->prom[5] << 8); + off = ((s64)st->prom[2] << 16) + ((st->prom[4] * dt) >> 7); + sens = ((s64)st->prom[1] << 15) + ((st->prom[3] * dt) >> 8); + + t = 2000 + ((st->prom[6] * dt) >> 23); + if (t < 2000) { + s64 off2, sens2, t2; + + t2 = (dt * dt) >> 31; + off2 = (5 * (t - 2000) * (t - 2000)) >> 1; + sens2 = off2 >> 1; + + if (t < -1500) { + s64 tmp = (t + 1500) * (t + 1500); + + off2 += 7 * tmp; + sens2 += (11 * tmp) >> 1; + } + + t -= t2; + off -= off2; + sens -= sens2; + } + + *temp = t; + *pressure = (((p * sens) >> 21) - off) >> 15; + + return 0; +} + +static int ms5611_reset(struct iio_dev *indio_dev) +{ + int ret; + struct ms5611_state *st = iio_priv(indio_dev); + + ret = st->reset(&indio_dev->dev); + if (ret < 0) { + dev_err(&indio_dev->dev, "failed to reset device\n"); + return ret; + } + + usleep_range(3000, 4000); + + return 0; +} + +static int ms5611_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + int ret; + s32 temp, pressure; + struct ms5611_state *st = iio_priv(indio_dev); + + switch (mask) { + case IIO_CHAN_INFO_PROCESSED: + mutex_lock(&st->lock); + ret = ms5611_read_temp_and_pressure(indio_dev, + &temp, &pressure); + mutex_unlock(&st->lock); + if (ret < 0) + return ret; + + switch (chan->type) { + case IIO_TEMP: + *val = temp * 10; + return IIO_VAL_INT; + case IIO_PRESSURE: + *val = pressure / 1000; + *val2 = (pressure % 1000) * 1000; + return IIO_VAL_INT_PLUS_MICRO; + default: + return -EINVAL; + } + } + + return -EINVAL; +} + +static const struct iio_chan_spec ms5611_channels[] = { + { + .type = IIO_PRESSURE, + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) | + BIT(IIO_CHAN_INFO_SCALE) + }, + { + .type = IIO_TEMP, + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) | + BIT(IIO_CHAN_INFO_SCALE) + } +}; + +static const struct iio_info ms5611_info = { + .read_raw = &ms5611_read_raw, + .driver_module = THIS_MODULE, +}; + +static int ms5611_init(struct iio_dev *indio_dev) +{ + int ret; + + ret = ms5611_reset(indio_dev); + if (ret < 0) + return ret; + + return ms5611_read_prom(indio_dev); +} + +int ms5611_probe(struct iio_dev *indio_dev, struct device *dev) +{ + int ret; + struct ms5611_state *st = iio_priv(indio_dev); + + mutex_init(&st->lock); + indio_dev->dev.parent = dev; + indio_dev->name = dev->driver->name; + indio_dev->info = &ms5611_info; + indio_dev->channels = ms5611_channels; + indio_dev->num_channels = ARRAY_SIZE(ms5611_channels); + indio_dev->modes = INDIO_DIRECT_MODE; + + ret = ms5611_init(indio_dev); + if (ret < 0) + return ret; + + return devm_iio_device_register(dev, indio_dev); +} +EXPORT_SYMBOL(ms5611_probe); + +MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>"); +MODULE_DESCRIPTION("MS5611 core driver"); +MODULE_LICENSE("GPL v2"); |