/*
   * 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
   *  http://www.meas-spec.com/downloads/MS5607-02BA03.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->chip_info->prom[i]);
  		if (ret < 0) {
  			dev_err(&indio_dev->dev,
  				"failed to read prom at %d
  ", i);
  			return ret;
  		}
  	}
  
  	if (!ms5611_prom_is_valid(st->chip_info->prom, MS5611_PROM_WORDS_NB)) {
  		dev_err(&indio_dev->dev, "PROM integrity check failed
  ");
  		return -ENODEV;
  	}
  
  	return 0;
  }
  
  static int ms5611_read_temp_and_pressure(struct iio_dev *indio_dev,
  					 s32 *temp, s32 *pressure)
  {
  	int ret;
  	struct ms5611_state *st = iio_priv(indio_dev);
  
  	ret = st->read_adc_temp_and_pressure(&indio_dev->dev, temp, pressure);
  	if (ret < 0) {
  		dev_err(&indio_dev->dev,
  			"failed to read temperature and pressure
  ");
  		return ret;
  	}
  
  	return st->chip_info->temp_and_pressure_compensate(st->chip_info,
  							   temp, pressure);
  }
  
  static int ms5611_temp_and_pressure_compensate(struct ms5611_chip_info *chip_info,
  					       s32 *temp, s32 *pressure)
  {
  	s32 t = *temp, p = *pressure;
  	s64 off, sens, dt;
  
  	dt = t - (chip_info->prom[5] << 8);
  	off = ((s64)chip_info->prom[2] << 16) + ((chip_info->prom[4] * dt) >> 7);
  	sens = ((s64)chip_info->prom[1] << 15) + ((chip_info->prom[3] * dt) >> 8);
  
  	t = 2000 + ((chip_info->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 ms5607_temp_and_pressure_compensate(struct ms5611_chip_info *chip_info,
  					       s32 *temp, s32 *pressure)
  {
  	s32 t = *temp, p = *pressure;
  	s64 off, sens, dt;
  
  	dt = t - (chip_info->prom[5] << 8);
  	off = ((s64)chip_info->prom[2] << 17) + ((chip_info->prom[4] * dt) >> 6);
  	sens = ((s64)chip_info->prom[1] << 16) + ((chip_info->prom[3] * dt) >> 7);
  
  	t = 2000 + ((chip_info->prom[6] * dt) >> 23);
  	if (t < 2000) {
  		s64 off2, sens2, t2;
  
  		t2 = (dt * dt) >> 31;
  		off2 = (61 * (t - 2000) * (t - 2000)) >> 4;
  		sens2 = off2 << 1;
  
  		if (t < -1500) {
  			s64 tmp = (t + 1500) * (t + 1500);
  
  			off2 += 15 * tmp;
  			sens2 += (8 * tmp);
  		}
  
  		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
  ");
  		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 struct ms5611_chip_info chip_info_tbl[] = {
  	[MS5611] = {
  		.temp_and_pressure_compensate = ms5611_temp_and_pressure_compensate,
  	},
  	[MS5607] = {
  		.temp_and_pressure_compensate = ms5607_temp_and_pressure_compensate,
  	}
  };
  
  static const struct iio_chan_spec ms5611_channels[] = {
  	{
  		.type = IIO_PRESSURE,
  		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
  	},
  	{
  		.type = IIO_TEMP,
  		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
  	}
  };
  
  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 type)
  {
  	int ret;
  	struct ms5611_state *st = iio_priv(indio_dev);
  
  	mutex_init(&st->lock);
  	st->chip_info = &chip_info_tbl[type];
  	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");