text: /****************************************************************************
   *
   *   Copyright (c) 2014-2015 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
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
   * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   *
   ****************************************************************************/
  
  /**
   * @file sf0x.cpp
   * @author Lorenz Meier <lm@inf.ethz.ch>
   * @author Greg Hulands
   *
   * Driver for the Lightware SF0x laser rangefinder series
   */
  
  #include <px4_config.h>
  #include <px4_getopt.h>
  #include <px4_workqueue.h>
  
  #include <sys/types.h>
  #include <stdint.h>
  #include <stdlib.h>
  #include <stdbool.h>
  #include <semaphore.h>
  #include <string.h>
  #include <fcntl.h>
  #include <poll.h>
  #include <errno.h>
  #include <stdio.h>
  #include <math.h>
  #include <unistd.h>
  #include <termios.h>
  
  #include <perf/perf_counter.h>
  #include <systemlib/err.h>
  
  #include <drivers/drv_hrt.h>
  #include <drivers/drv_range_finder.h>
  #include <drivers/device/device.h>
  #include <drivers/device/ringbuffer.h>
  
  #include <uORB/uORB.h>
  #include <uORB/topics/distance_sensor.h>
  
  #include "sf0x_parser.h"
  
  /* Configuration Constants */
  
  #ifndef CONFIG_SCHED_WORKQUEUE
  # error This requires CONFIG_SCHED_WORKQUEUE.
  #endif
  
  #define SF0X_TAKE_RANGE_REG		'd'
  
  // designated SERIAL4/5 on Pixhawk
  #define SF0X_DEFAULT_PORT		"/dev/ttyS6"
  
  class SF0X : public device::CDev
  {
  public:
  	SF0X(const char *port = SF0X_DEFAULT_PORT, uint8_t rotation = distance_sensor_s::ROTATION_DOWNWARD_FACING);
  	virtual ~SF0X();
  
  	virtual int 			init();
  
  	virtual ssize_t			read(device::file_t *filp, char *buffer, size_t buflen);
  	virtual int			ioctl(device::file_t *filp, int cmd, unsigned long arg);
  
  	/**
  	* Diagnostics - print some basic information about the driver.
  	*/
  	void				print_info();
  
  protected:
  	virtual int			probe();
  
  private:
  	char 				_port[20];
  	uint8_t _rotation;
  	float				_min_distance;
  	float				_max_distance;
  	int                 _conversion_interval;
  	work_s				_work;
  	ringbuffer::RingBuffer		*_reports;
  	int				_measure_ticks;
  	bool				_collect_phase;
  	int				_fd;
  	char				_linebuf[10];
  	unsigned			_linebuf_index;
  	enum SF0X_PARSE_STATE		_parse_state;
  	hrt_abstime			_last_read;
  
  	int				_class_instance;
  	int				_orb_class_instance;
  
  	orb_advert_t			_distance_sensor_topic;
  
  	unsigned			_consecutive_fail_count;
  
  	perf_counter_t			_sample_perf;
  	perf_counter_t			_comms_errors;
  
  	/**
  	* Initialise the automatic measurement state machine and start it.
  	*
  	* @note This function is called at open and error time.  It might make sense
  	*       to make it more aggressive about resetting the bus in case of errors.
  	*/
  	void				start();
  
  	/**
  	* Stop the automatic measurement state machine.
  	*/
  	void				stop();
  
  	/**
  	* Set the min and max distance thresholds if you want the end points of the sensors
  	* range to be brought in at all, otherwise it will use the defaults SF0X_MIN_DISTANCE
  	* and SF0X_MAX_DISTANCE
  	*/
  	void				set_minimum_distance(float min);
  	void				set_maximum_distance(float max);
  	float				get_minimum_distance();
  	float				get_maximum_distance();
  
  	/**
  	* Perform a poll cycle; collect from the previous measurement
  	* and start a new one.
  	*/
  	void				cycle();
  	int				measure();
  	int				collect();
  	/**
  	* Static trampoline from the workq context; because we don't have a
  	* generic workq wrapper yet.
  	*
  	* @param arg		Instance pointer for the driver that is polling.
  	*/
  	static void			cycle_trampoline(void *arg);
  
  
  };
  
  /*
   * Driver 'main' command.
   */
  extern "C" __EXPORT int sf0x_main(int argc, char *argv[]);
  
  SF0X::SF0X(const char *port, uint8_t rotation) :
  	CDev("SF0X", RANGE_FINDER0_DEVICE_PATH),
  	_rotation(rotation),
  	_min_distance(0.30f),
  	_max_distance(40.0f),
  	_conversion_interval(83334),
  	_reports(nullptr),
  	_measure_ticks(0),
  	_collect_phase(false),
  	_fd(-1),
  	_linebuf_index(0),
  	_parse_state(SF0X_PARSE_STATE0_UNSYNC),
  	_last_read(0),
  	_class_instance(-1),
  	_orb_class_instance(-1),
  	_distance_sensor_topic(nullptr),
  	_consecutive_fail_count(0),
  	_sample_perf(perf_alloc(PC_ELAPSED, "sf0x_read")),
  	_comms_errors(perf_alloc(PC_COUNT, "sf0x_com_err"))
  {
  	/* store port name */
  	strncpy(_port, port, sizeof(_port));
  	/* enforce null termination */
  	_port[sizeof(_port) - 1] = '\0';
  
  	/* open fd */
  	_fd = ::open(_port, O_RDWR | O_NOCTTY | O_NONBLOCK);
  
  	if (_fd < 0) {
  		warnx("FAIL: laser fd");
  	}
  
  	struct termios uart_config;
  
  	int termios_state;
  
  	/* fill the struct for the new configuration */
  	tcgetattr(_fd, &uart_config);
  
  	/* clear ONLCR flag (which appends a CR for every LF) */
  	uart_config.c_oflag &= ~ONLCR;
  
  	/* no parity, one stop bit */
  	uart_config.c_cflag &= ~(CSTOPB | PARENB);
  
  	unsigned speed = B9600;
  
  	/* set baud rate */
  	if ((termios_state = cfsetispeed(&uart_config, speed)) < 0) {
  		warnx("ERR CFG: %d ISPD", termios_state);
  	}
  
  	if ((termios_state = cfsetospeed(&uart_config, speed)) < 0) {
  		warnx("ERR CFG: %d OSPD\n", termios_state);
  	}
  
  	if ((termios_state = tcsetattr(_fd, TCSANOW, &uart_config)) < 0) {
  		warnx("ERR baud %d ATTR", termios_state);
  	}
  
  	// disable debug() calls
  	_debug_enabled = false;
  
  	// work_cancel in the dtor will explode if we don't do this...
  	memset(&_work, 0, sizeof(_work));
  }
  
  SF0X::~SF0X()
  {
  	/* make sure we are truly inactive */
  	stop();
  
  	/* free any existing reports */
  	if (_reports != nullptr) {
  		delete _reports;
  	}
  
  	if (_class_instance != -1) {
  		unregister_class_devname(RANGE_FINDER_BASE_DEVICE_PATH, _class_instance);
  	}
  
  	perf_free(_sample_perf);
  	perf_free(_comms_errors);
  }
  
  int
  SF0X::init()
  {
  	int hw_model;
  	param_get(param_find("SENS_EN_SF0X"), &hw_model);
  
  	switch (hw_model) {
  	case 0:
  		DEVICE_LOG("disabled.");
  		return 0;
  
  	case 1: /* SF02 (40m, 12 Hz)*/
  		_min_distance = 0.3f;
  		_max_distance = 40.0f;
  		_conversion_interval =	83334;
  		break;
  
  	case 2:  /* SF10/a (25m 32Hz) */
  		_min_distance = 0.01f;
  		_max_distance = 25.0f;
  		_conversion_interval = 31250;
  		break;
  
  	case 3:  /* SF10/b (50m 32Hz) */
  		_min_distance = 0.01f;
  		_max_distance = 50.0f;
  		_conversion_interval = 31250;
  		break;
  
  	case 4:  /* SF10/c (100m 16Hz) */
  		_min_distance = 0.01f;
  		_max_distance = 100.0f;
  		_conversion_interval = 62500;
  		break;
  
  	case 5:
  		/* SF11/c (120m 20Hz) */
  		_min_distance = 0.01f;
  		_max_distance = 120.0f;
  		_conversion_interval = 50000;
  		break;
  
  	default:
  		DEVICE_LOG("invalid HW model %d.", hw_model);
  		return -1;
  	}
  
  	/* status */
  	int ret = 0;
  
  	do { /* create a scope to handle exit conditions using break */
  
  		/* do regular cdev init */
  		ret = CDev::init();
  
  		if (ret != OK) { break; }
  
  		/* allocate basic report buffers */
  		_reports = new ringbuffer::RingBuffer(2, sizeof(distance_sensor_s));
  
  		if (_reports == nullptr) {
  			warnx("mem err");
  			ret = -1;
  			break;
  		}
  
  		_class_instance = register_class_devname(RANGE_FINDER_BASE_DEVICE_PATH);
  
  		/* get a publish handle on the range finder topic */
  		struct distance_sensor_s ds_report = {};
  
  		_distance_sensor_topic = orb_advertise_multi(ORB_ID(distance_sensor), &ds_report,
  					 &_orb_class_instance, ORB_PRIO_HIGH);
  
  		if (_distance_sensor_topic == nullptr) {
  			DEVICE_LOG("failed to create distance_sensor object. Did you start uOrb?");
  		}
  
  	} while (0);
  
  	/* close the fd */
  	::close(_fd);
  	_fd = -1;
  
  	return OK;
  }
  
  int
  SF0X::probe()
  {
  	return measure();
  }
  
  void
  SF0X::set_minimum_distance(float min)
  {
  	_min_distance = min;
  }
  
  void
  SF0X::set_maximum_distance(float max)
  {
  	_max_distance = max;
  }
  
  float
  SF0X::get_minimum_distance()
  {
  	return _min_distance;
  }
  
  float
  SF0X::get_maximum_distance()
  {
  	return _max_distance;
  }
  
  int
  SF0X::ioctl(device::file_t *filp, int cmd, unsigned long arg)
  {
  	switch (cmd) {
  
  	case SENSORIOCSPOLLRATE: {
  			switch (arg) {
  
  			/* switching to manual polling */
  			case SENSOR_POLLRATE_MANUAL:
  				stop();
  				_measure_ticks = 0;
  				return OK;
  
  			/* external signalling (DRDY) not supported */
  			case SENSOR_POLLRATE_EXTERNAL:
  
  			/* zero would be bad */
  			case 0:
  				return -EINVAL;
  
  			/* set default/max polling rate */
  			case SENSOR_POLLRATE_MAX:
  			case SENSOR_POLLRATE_DEFAULT: {
  					/* do we need to start internal polling? */
  					bool want_start = (_measure_ticks == 0);
  
  					/* set interval for next measurement to minimum legal value */
  					_measure_ticks = USEC2TICK(_conversion_interval);
  
  					/* if we need to start the poll state machine, do it */
  					if (want_start) {
  						start();
  					}
  
  					return OK;
  				}
  
  			/* adjust to a legal polling interval in Hz */
  			default: {
  
  					/* do we need to start internal polling? */
  					bool want_start = (_measure_ticks == 0);
  
  					/* convert hz to tick interval via microseconds */
  					unsigned ticks = USEC2TICK(1000000 / arg);
  
  					/* check against maximum rate */
  					if (ticks < USEC2TICK(_conversion_interval)) {
  						return -EINVAL;
  					}
  
  					/* update interval for next measurement */
  					_measure_ticks = ticks;
  
  					/* if we need to start the poll state machine, do it */
  					if (want_start) {
  						start();
  					}
  
  					return OK;
  				}
  			}
  		}
  
  	case SENSORIOCGPOLLRATE:
  		if (_measure_ticks == 0) {
  			return SENSOR_POLLRATE_MANUAL;
  		}
  
  		return (1000 / _measure_ticks);
  
  	case SENSORIOCSQUEUEDEPTH: {
  			/* lower bound is mandatory, upper bound is a sanity check */
  			if ((arg < 1) || (arg > 100)) {
  				return -EINVAL;
  			}
  
  			ATOMIC_ENTER;
  
  			if (!_reports->resize(arg)) {
  				ATOMIC_LEAVE;
  				return -ENOMEM;
  			}
  
  			ATOMIC_LEAVE;
  
  			return OK;
  		}
  
  	case SENSORIOCRESET:
  		/* XXX implement this */
  		return -EINVAL;
  
  	default:
  		/* give it to the superclass */
  		return CDev::ioctl(filp, cmd, arg);
  	}
  }
  
  ssize_t
  SF0X::read(device::file_t *filp, char *buffer, size_t buflen)
  {
  	unsigned count = buflen / sizeof(struct distance_sensor_s);
  	struct distance_sensor_s *rbuf = reinterpret_cast<struct distance_sensor_s *>(buffer);
  	int ret = 0;
  
  	/* buffer must be large enough */
  	if (count < 1) {
  		return -ENOSPC;
  	}
  
  	/* if automatic measurement is enabled */
  	if (_measure_ticks > 0) {
  
  		/*
  		 * While there is space in the caller's buffer, and reports, copy them.
  		 * Note that we may be pre-empted by the workq thread while we are doing this;
  		 * we are careful to avoid racing with them.
  		 */
  		while (count--) {
  			if (_reports->get(rbuf)) {
  				ret += sizeof(*rbuf);
  				rbuf++;
  			}
  		}
  
  		/* if there was no data, warn the caller */
  		return ret ? ret : -EAGAIN;
  	}
  
  	/* manual measurement - run one conversion */
  	do {
  		_reports->flush();
  
  		/* trigger a measurement */
  		if (OK != measure()) {
  			ret = -EIO;
  			break;
  		}
  
  		/* wait for it to complete */
  		usleep(_conversion_interval);
  
  		/* run the collection phase */
  		if (OK != collect()) {
  			ret = -EIO;
  			break;
  		}
  
  		/* state machine will have generated a report, copy it out */
  		if (_reports->get(rbuf)) {
  			ret = sizeof(*rbuf);
  		}
  
  	} while (0);
  
  	return ret;
  }
  
  int
  SF0X::measure()
  {
  	int ret;
  
  	/*
  	 * Send the command to begin a measurement.
  	 */
  	char cmd = SF0X_TAKE_RANGE_REG;
  	ret = ::write(_fd, &cmd, 1);
  
  	if (ret != sizeof(cmd)) {
  		perf_count(_comms_errors);
  		DEVICE_LOG("write fail %d", ret);
  		return ret;
  	}
  
  	ret = OK;
  
  	return ret;
  }
  
  int
  SF0X::collect()
  {
  	int	ret;
  
  	perf_begin(_sample_perf);
  
  	/* clear buffer if last read was too long ago */
  	uint64_t read_elapsed = hrt_elapsed_time(&_last_read);
  
  	/* the buffer for read chars is buflen minus null termination */
  	char readbuf[sizeof(_linebuf)];
  	unsigned readlen = sizeof(readbuf) - 1;
  
  	/* read from the sensor (uart buffer) */
  	ret = ::read(_fd, &readbuf[0], readlen);
  
  	if (ret < 0) {
  		DEVICE_DEBUG("read err: %d", ret);
  		perf_count(_comms_errors);
  		perf_end(_sample_perf);
  
  		/* only throw an error if we time out */
  		if (read_elapsed > (_conversion_interval * 2)) {
  			return ret;
  
  		} else {
  			return -EAGAIN;
  		}
  
  	} else if (ret == 0) {
  		return -EAGAIN;
  	}
  
  	_last_read = hrt_absolute_time();
  
  	float distance_m = -1.0f;
  	bool valid = false;
  
  	for (int i = 0; i < ret; i++) {
  		if (OK == sf0x_parser(readbuf[i], _linebuf, &_linebuf_index, &_parse_state, &distance_m)) {
  			valid = true;
  		}
  	}
  
  	if (!valid) {
  		return -EAGAIN;
  	}
  
  	DEVICE_DEBUG("val (float): %8.4f, raw: %s, valid: %s", (double)distance_m, _linebuf, ((valid) ? "OK" : "NO"));
  
  	struct distance_sensor_s report;
  
  	report.timestamp = hrt_absolute_time();
  	report.type = distance_sensor_s::MAV_DISTANCE_SENSOR_LASER;
  	report.orientation = _rotation;
  	report.current_distance = distance_m;
  	report.min_distance = get_minimum_distance();
  	report.max_distance = get_maximum_distance();
  	report.covariance = 0.0f;
  	/* TODO: set proper ID */
  	report.id = 0;
  
  	/* publish it */
  	orb_publish(ORB_ID(distance_sensor), _distance_sensor_topic, &report);
  
  	_reports->force(&report);
  
  	/* notify anyone waiting for data */
  	poll_notify(POLLIN);
  
  	ret = OK;
  
  	perf_end(_sample_perf);
  	return ret;
  }
  
  void
  SF0X::start()
  {
  	/* reset the report ring and state machine */
  	_collect_phase = false;
  	_reports->flush();
  
  	/* schedule a cycle to start things */
  	work_queue(HPWORK, &_work, (worker_t)&SF0X::cycle_trampoline, this, 1);
  
  }
  
  void
  SF0X::stop()
  {
  	work_cancel(HPWORK, &_work);
  }
  
  void
  SF0X::cycle_trampoline(void *arg)
  {
  	SF0X *dev = static_cast<SF0X *>(arg);
  
  	dev->cycle();
  }
  
  void
  SF0X::cycle()
  {
  	/* fds initialized? */
  	if (_fd < 0) {
  		/* open fd */
  		_fd = ::open(_port, O_RDWR | O_NOCTTY | O_NONBLOCK);
  	}
  
  	/* collection phase? */
  	if (_collect_phase) {
  
  		/* perform collection */
  		int collect_ret = collect();
  
  		if (collect_ret == -EAGAIN) {
  			/* reschedule to grab the missing bits, time to transmit 8 bytes @ 9600 bps */
  			work_queue(HPWORK,
  				   &_work,
  				   (worker_t)&SF0X::cycle_trampoline,
  				   this,
  				   USEC2TICK(1042 * 8));
  			return;
  		}
  
  		if (OK != collect_ret) {
  
  			/* we know the sensor needs about four seconds to initialize */
  			if (hrt_absolute_time() > 5 * 1000 * 1000LL && _consecutive_fail_count < 5) {
  				DEVICE_LOG("collection error #%u", _consecutive_fail_count);
  			}
  
  			_consecutive_fail_count++;
  
  			/* restart the measurement state machine */
  			start();
  			return;
  
  		} else {
  			/* apparently success */
  			_consecutive_fail_count = 0;
  		}
  
  		/* next phase is measurement */
  		_collect_phase = false;
  
  		/*
  		 * Is there a collect->measure gap?
  		 */
  		if (_measure_ticks > USEC2TICK(_conversion_interval)) {
  
  			/* schedule a fresh cycle call when we are ready to measure again */
  			work_queue(HPWORK,
  				   &_work,
  				   (worker_t)&SF0X::cycle_trampoline,
  				   this,
  				   _measure_ticks - USEC2TICK(_conversion_interval));
  
  			return;
  		}
  	}
  
  	/* measurement phase */
  	if (OK != measure()) {
  		DEVICE_LOG("measure error");
  	}
  
  	/* next phase is collection */
  	_collect_phase = true;
  
  	/* schedule a fresh cycle call when the measurement is done */
  	work_queue(HPWORK,
  		   &_work,
  		   (worker_t)&SF0X::cycle_trampoline,
  		   this,
  		   USEC2TICK(_conversion_interval));
  }
  
  void
  SF0X::print_info()
  {
  	perf_print_counter(_sample_perf);
  	perf_print_counter(_comms_errors);
  	printf("poll interval:  %d ticks\n", _measure_ticks);
  	_reports->print_info("report queue");
  }
  
  /**
   * Local functions in support of the shell command.
   */
  namespace sf0x
  {
  
  SF0X	*g_dev;
  
  void	start(const char *port, uint8_t rotation);
  void	stop();
  void	test();
  void	reset();
  void	info();
  
  /**
   * Start the driver.
   */
  void
  start(const char *port, uint8_t rotation)
  {
  	int fd;
  
  	if (g_dev != nullptr) {
  		errx(1, "already started");
  	}
  
  	/* create the driver */
  	g_dev = new SF0X(port, rotation);
  
  	if (g_dev == nullptr) {
  		goto fail;
  	}
  
  	if (OK != g_dev->init()) {
  		goto fail;
  	}
  
  	/* set the poll rate to default, starts automatic data collection */
  	fd = open(RANGE_FINDER0_DEVICE_PATH, 0);
  
  	if (fd < 0) {
  		warnx("device open fail");
  		goto fail;
  	}
  
  	if (ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT) < 0) {
  		goto fail;
  	}
  
  	exit(0);
  
  fail:
  
  	if (g_dev != nullptr) {
  		delete g_dev;
  		g_dev = nullptr;
  	}
  
  	errx(1, "driver start failed");
  }
  
  /**
   * Stop the driver
   */
  void stop()
  {
  	if (g_dev != nullptr) {
  		delete g_dev;
  		g_dev = nullptr;
  
  	} else {
  		errx(1, "driver not running");
  	}
  
  	exit(0);
  }
  
  /**
   * Perform some basic functional tests on the driver;
   * make sure we can collect data from the sensor in polled
   * and automatic modes.
   */
  void
  test()
  {
  	struct distance_sensor_s report;
  	ssize_t sz;
  
  	int fd = open(RANGE_FINDER0_DEVICE_PATH, O_RDONLY);
  
  	if (fd < 0) {
  		err(1, "%s open failed (try 'sf0x start' if the driver is not running", RANGE_FINDER0_DEVICE_PATH);
  	}
  
  	/* do a simple demand read */
  	sz = read(fd, &report, sizeof(report));
  
  	if (sz != sizeof(report)) {
  		err(1, "immediate read failed");
  	}
  
  	print_message(report);
  
  	/* start the sensor polling at 2 Hz rate */
  	if (OK != ioctl(fd, SENSORIOCSPOLLRATE, 2)) {
  		errx(1, "failed to set 2Hz poll rate");
  	}
  
  	/* read the sensor 5x and report each value */
  	for (unsigned i = 0; i < 5; i++) {
  		struct pollfd fds;
  
  		/* wait for data to be ready */
  		fds.fd = fd;
  		fds.events = POLLIN;
  		int ret = poll(&fds, 1, 2000);
  
  		if (ret != 1) {
  			warnx("timed out");
  			break;
  		}
  
  		/* now go get it */
  		sz = read(fd, &report, sizeof(report));
  
  		if (sz != sizeof(report)) {
  			warnx("read failed: got %d vs exp. %d", sz, sizeof(report));
  			break;
  		}
  
  		print_message(report);
  	}
  
  	/* reset the sensor polling to the default rate */
  	if (OK != ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT)) {
  		errx(1, "ERR: DEF RATE");
  	}
  
  	errx(0, "PASS");
  }
  
  /**
   * Reset the driver.
   */
  void
  reset()
  {
  	int fd = open(RANGE_FINDER0_DEVICE_PATH, O_RDONLY);
  
  	if (fd < 0) {
  		err(1, "failed ");
  	}
  
  	if (ioctl(fd, SENSORIOCRESET, 0) < 0) {
  		err(1, "driver reset failed");
  	}
  
  	if (ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT) < 0) {
  		err(1, "driver poll restart failed");
  	}
  
  	exit(0);
  }
  
  /**
   * Print a little info about the driver.
   */
  void
  info()
  {
  	if (g_dev == nullptr) {
  		errx(1, "driver not running");
  	}
  
  	printf("state @ %p\n", g_dev);
  	g_dev->print_info();
  
  	exit(0);
  }
  
  } // namespace
  
  int
  sf0x_main(int argc, char *argv[])
  {
  	int ch;
  	uint8_t rotation = distance_sensor_s::ROTATION_DOWNWARD_FACING;
  	int myoptind = 1;
  	const char *myoptarg = nullptr;
  
  	while ((ch = px4_getopt(argc, argv, "R:", &myoptind, &myoptarg)) != EOF) {
  		switch (ch) {
  		case 'R':
  			rotation = (uint8_t)atoi(myoptarg);
  			break;
  
  		default:
  			PX4_WARN("Unknown option!");
  			return -1;
  		}
  	}
  
  	if (myoptind >= argc) {
  		goto out_error;
  	}
  
  	/*
  	 * Start/load the driver.
  	 */
  	if (!strcmp(argv[myoptind], "start")) {
  		if (argc > myoptind + 1) {
  			sf0x::start(argv[myoptind + 1], rotation);
  
  		} else {
  			sf0x::start(SF0X_DEFAULT_PORT, rotation);
  		}
  	}
  
  	/*
  	 * Stop the driver
  	 */
  	if (!strcmp(argv[myoptind], "stop")) {
  		sf0x::stop();
  	}
  
  	/*
  	 * Test the driver/device.
  	 */
  	if (!strcmp(argv[myoptind], "test")) {
  		sf0x::test();
  	}
  
  	/*
  	 * Reset the driver.
  	 */
  	if (!strcmp(argv[myoptind], "reset")) {
  		sf0x::reset();
  	}
  
  	/*
  	 * Print driver information.
  	 */
  	if (!strcmp(argv[myoptind], "info") || !strcmp(argv[myoptind], "status")) {
  		sf0x::info();
  	}
  
  out_error:
  	PX4_ERR("unrecognized command, try 'start', 'test', 'reset' or 'info'");
  	return -1;
  }
  