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 /**
  * @file ms5611_i2c.cpp
  *
  * I2C interface for MS5611
  */

/* XXX trim includes */
#include <nuttx/config.h>

#include <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <assert.h>
#include <debug.h>
#include <errno.h>
#include <unistd.h>

#include <arch/board/board.h>

#include <drivers/device/i2c.h>

#include "ms5611.h"

#include "board_config.h"

#define MS5611_ADDRESS_1		0x76	/* address select pins pulled high (PX4FMU series v1.6+) */
#define MS5611_ADDRESS_2		0x77    /* address select pins pulled low (PX4FMU prototypes) */



device::Device *MS5611_i2c_interface(ms5611::prom_u &prom_buf);

class MS5611_I2C : public device::I2C
{
public:
	MS5611_I2C(uint8_t bus, ms5611::prom_u &prom_buf);
	virtual ~MS5611_I2C();

	virtual int	init();
	virtual int	read(unsigned offset, void *data, unsigned count);
	virtual int	ioctl(unsigned operation, unsigned &arg);

protected:
	virtual int	probe();

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		OK if the PROM reads successfully.
	 */
	int		_read_prom();

};

device::Device *
MS5611_i2c_interface(ms5611::prom_u &prom_buf, uint8_t busnum)
{
	return new MS5611_I2C(busnum, prom_buf);
}

MS5611_I2C::MS5611_I2C(uint8_t bus, ms5611::prom_u &prom) :
	I2C("MS5611_I2C", nullptr, bus, 0, 400000),
	_prom(prom)
{
}

MS5611_I2C::~MS5611_I2C()
{
}

int
MS5611_I2C::init()
{
	/* this will call probe(), and thereby _probe_address */
	return I2C::init();
}

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 == 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()
{
	_retries = 10;

	if ((OK == _probe_address(MS5611_ADDRESS_1)) ||
	    (OK == _probe_address(MS5611_ADDRESS_2))) {
		/*
	    	 * Disable retries; we may enable them selectively in some cases,
		 * but the device gets confused if we retry some of the commands.
	    	 */
		_retries = 0;
		return OK;
	}

	return -EIO;
}

int
MS5611_I2C::_probe_address(uint8_t address)
{
	/* select the address we are going to try */
	set_address(address);

	/* send reset command */
	if (OK != _reset())
		return -EIO;

	/* read PROM */
	if (OK != _read_prom())
		return -EIO;

	return OK;
}


int
MS5611_I2C::_reset()
{
	unsigned	old_retrycount = _retries;
	uint8_t		cmd = ADDR_RESET_CMD;
	int		result;

	/* bump the retry count */
	_retries = 10;
	result = transfer(&cmd, 1, nullptr, 0);
	_retries = old_retrycount;

	return result;
}

int
MS5611_I2C::_measure(unsigned addr)
{
	/*
	 * Disable retries on this command; we can't know whether failure 
	 * means the device did or did not see the command.
	 */
	_retries = 0;

	uint8_t cmd = addr;
	return transfer(&cmd, 1, nullptr, 0);
}

int
MS5611_I2C::_read_prom()
{
	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.
	 */
	usleep(3000);

	/* read and convert PROM words */
	for (int i = 0; i < 8; i++) {
		uint8_t cmd = ADDR_PROM_SETUP + (i * 2);

		if (OK != transfer(&cmd, 1, &prom_buf[0], 2))
			break;

		/* 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]) ? OK : -EIO;
}