text: /****************************************************************************
   *
   *   Copyright (c) 2013-2019 PX4 Development Team. All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   * 3. Neither the name PX4 nor the names of its contributors may be
   *    used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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   * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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   *
   ****************************************************************************/
  
  /**
   * @file ms5611_i2c.cpp
   *
   * I2C interface for MS5611
   */
  
  #include <drivers/device/i2c.h>
  
  #if defined(CONFIG_I2C)
  
  #include "ms5611.h"
  
  class MS5611_I2C : public device::I2C
  {
  public:
  	MS5611_I2C(uint8_t bus, ms5611::prom_u &prom_buf, int bus_frequency);
  	~MS5611_I2C() override = default;
  
  	int	read(unsigned offset, void *data, unsigned count) override;
  	int	ioctl(unsigned operation, unsigned &arg) override;
  
  protected:
  	int	probe() override;
  
  private:
  	ms5611::prom_u	&_prom;
  
  	int		_probe_address(uint8_t address);
  
  	/**
  	 * Send a reset command to the MS5611.
  	 *
  	 * This is required after any bus reset.
  	 */
  	int		_reset();
  
  	/**
  	 * Send a measure command to the MS5611.
  	 *
  	 * @param addr		Which address to use for the measure operation.
  	 */
  	int		_measure(unsigned addr);
  
  	/**
  	 * Read the MS5611 PROM
  	 *
  	 * @return		PX4_OK if the PROM reads successfully.
  	 */
  	int		_read_prom();
  
  };
  
  device::Device *
  MS5611_i2c_interface(ms5611::prom_u &prom_buf, uint32_t devid, uint8_t busnum, int bus_frequency)
  {
  	return new MS5611_I2C(busnum, prom_buf, bus_frequency);
  }
  
  MS5611_I2C::MS5611_I2C(uint8_t bus, ms5611::prom_u &prom, int bus_frequency) :
  	I2C(DRV_BARO_DEVTYPE_MS5611, MODULE_NAME, bus, 0, bus_frequency),
  	_prom(prom)
  {
  }
  
  int
  MS5611_I2C::read(unsigned offset, void *data, unsigned count)
  {
  	union _cvt {
  		uint8_t	b[4];
  		uint32_t w;
  	} *cvt = (_cvt *)data;
  	uint8_t buf[3];
  
  	/* read the most recent measurement */
  	uint8_t cmd = 0;
  	int ret = transfer(&cmd, 1, &buf[0], 3);
  
  	if (ret == PX4_OK) {
  		/* fetch the raw value */
  		cvt->b[0] = buf[2];
  		cvt->b[1] = buf[1];
  		cvt->b[2] = buf[0];
  		cvt->b[3] = 0;
  	}
  
  	return ret;
  }
  
  int
  MS5611_I2C::ioctl(unsigned operation, unsigned &arg)
  {
  	int ret;
  
  	switch (operation) {
  	case IOCTL_RESET:
  		ret = _reset();
  		break;
  
  	case IOCTL_MEASURE:
  		ret = _measure(arg);
  		break;
  
  	default:
  		ret = EINVAL;
  	}
  
  	return ret;
  }
  
  int
  MS5611_I2C::probe()
  {
  #ifdef REALDEV
          _retries = 10;
  
  	if ((PX4_OK == _probe_address(MS5611_ADDRESS_1)) ||
  	    (PX4_OK == _probe_address(MS5611_ADDRESS_2))) {
  
  		return PX4_OK;
  	}
  
  	_retries = 1;
  
  	return -EIO;
  #else // REALDEV
      return PX4_OK;
  #endif // REALDEV
  }
  
  int
  MS5611_I2C::_probe_address(uint8_t address)
  {
  #ifdef REALDEV
          /* select the address we are going to try */
  	set_device_address(address);
  
  	/* send reset command */
  	if (PX4_OK != _reset()) {
  		return -EIO;
  	}
  
  	/* read PROM */
  	if (PX4_OK != _read_prom()) {
  		return -EIO;
  	}
  
  	return PX4_OK;
  #else // REALDEV
      return PX4_OK;
  #endif // REALDEV
  }
  
  int
  MS5611_I2C::_reset()
  {
  #ifdef REALDEV
          unsigned	old_retrycount = _retries;
  	uint8_t		cmd = ADDR_RESET_CMD;
  	int		result;
  
  	/* bump the retry count */
  	_retries = 3;
  	result = transfer(&cmd, 1, nullptr, 0);
  	_retries = old_retrycount;
  
  	return result;
  #else // REALDEV
      return PX4_OK;
  #endif // REALDEV
  }
  
  int
  MS5611_I2C::_measure(unsigned addr)
  {
  #ifdef REALDEV
  	uint8_t cmd = addr;
  	return transfer(&cmd, 1, nullptr, 0);
  #else // REALDEV
      return PX4_OK;
  #endif // REALDEV
  }
  
  int
  MS5611_I2C::_read_prom()
  {
  #ifdef REALDEV
          uint8_t		prom_buf[2];
  	union {
  		uint8_t		b[2];
  		uint16_t	w;
  	} cvt;
  
  	/*
  	 * Wait for PROM contents to be in the device (2.8 ms) in the case we are
  	 * called immediately after reset.
  	 */
  	px4_usleep(3000);
  
  	uint8_t last_val = 0;
  	bool bits_stuck = true;
  
  	/* read and convert PROM words */
  	for (int i = 0; i < 8; i++) {
  		uint8_t cmd = ADDR_PROM_SETUP + (i * 2);
  
  		if (PX4_OK != transfer(&cmd, 1, &prom_buf[0], 2)) {
  			break;
  		}
  
  		/* check if all bytes are zero */
  		if (i == 0) {
  			/* initialize to first byte read */
  			last_val = prom_buf[0];
  		}
  
  		if ((prom_buf[0] != last_val) || (prom_buf[1] != last_val)) {
  			bits_stuck = false;
  		}
  
  		/* assemble 16 bit value and convert from big endian (sensor) to little endian (MCU) */
  		cvt.b[0] = prom_buf[1];
  		cvt.b[1] = prom_buf[0];
  		_prom.c[i] = cvt.w;
  	}
  
  	/* calculate CRC and return success/failure accordingly */
  	return (ms5611::crc4(&_prom.c[0]) && !bits_stuck) ? PX4_OK : -EIO;
  #else // REALDEV
      return PX4_OK;
  #endif // REALDEV
  }
  
  #endif // CONFIG_I2C
  