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  /**
   * @file LidarLitePWM.h
   * @author Johan Jansen <jnsn.johan@gmail.com>
   * @author Ban Siesta <bansiesta@gmail.com>
   *
   * Driver for the PulsedLight Lidar-Lite range finders connected via PWM.
   *
   * This driver accesses the pwm_input published by the pwm_input driver.
   */
  
  #include "LidarLitePWM.h"
  #include <stdio.h>
  #include <string.h>
  #include <px4_defines.h>
  #include <drivers/drv_hrt.h>
  #include <drivers/drv_pwm_input.h>
  
  LidarLitePWM::LidarLitePWM(const char *path, uint8_t rotation) :
  	CDev(path),
  	_rotation(rotation),
  	_work{},
  	_reports(nullptr),
  	_class_instance(-1),
  	_orb_class_instance(-1),
  	_pwmSub(-1),
  	_pwm{},
  	_distance_sensor_topic(nullptr),
  	_range{},
  	_sample_perf(perf_alloc(PC_ELAPSED, "ll40ls_pwm_read")),
  	_read_errors(perf_alloc(PC_COUNT, "ll40ls_pwm_read_errors")),
  	_sensor_zero_resets(perf_alloc(PC_COUNT, "ll40ls_pwm_zero_resets"))
  {
  }
  
  LidarLitePWM::~LidarLitePWM()
  {
  	stop();
  
  	/* free any existing reports */
  	if (_reports != nullptr) {
  		delete _reports;
  	}
  
  	if (_class_instance != -1) {
  		unregister_class_devname(RANGE_FINDER_BASE_DEVICE_PATH, _class_instance);
  	}
  
  	/* free perf counters */
  	perf_free(_sample_perf);
  	perf_free(_sensor_zero_resets);
  }
  
  
  int LidarLitePWM::init()
  {
  	/* do regular cdev init */
  	int ret = CDev::init();
  
  	if (ret != PX4_OK) {
  		return PX4_ERROR;
  	}
  
  	/* allocate basic report buffers */
  	_reports = new ringbuffer::RingBuffer(2, sizeof(struct distance_sensor_s));
  
  	if (_reports == nullptr) {
  		return PX4_ERROR;
  	}
  
  	_class_instance = register_class_devname(RANGE_FINDER_BASE_DEVICE_PATH);
  
  	/* get a publish handle on the distance_sensor topic */
  	struct distance_sensor_s ds_report = {};
  	measure();
  	_reports->get(&ds_report);
  	_distance_sensor_topic = orb_advertise_multi(ORB_ID(distance_sensor), &ds_report,
  				 &_orb_class_instance, ORB_PRIO_LOW);
  
  	if (_distance_sensor_topic == nullptr) {
  		PX4_DEBUG("failed to create distance_sensor object. Did you start uOrb?");
  	}
  
  	return PX4_OK;
  }
  
  void LidarLitePWM::print_info()
  {
  	perf_print_counter(_sample_perf);
  	perf_print_counter(_read_errors);
  	perf_print_counter(_sensor_zero_resets);
  	PX4_INFO("poll interval:  %u ticks", getMeasureTicks());
  
  	print_message(_range);
  }
  
  void LidarLitePWM::print_registers()
  {
  	printf("Not supported in PWM mode\n");
  }
  
  void LidarLitePWM::start()
  {
  	/* schedule a cycle to start things */
  	work_queue(HPWORK, &_work, (worker_t)&LidarLitePWM::cycle_trampoline, this, 1);
  }
  
  void LidarLitePWM::stop()
  {
  	work_cancel(HPWORK, &_work);
  }
  
  void LidarLitePWM::cycle_trampoline(void *arg)
  {
  	LidarLitePWM *dev = (LidarLitePWM *)arg;
  
  	dev->cycle();
  }
  
  void LidarLitePWM::cycle()
  {
  	measure();
  
  	/* schedule a fresh cycle call when the measurement is done */
  	work_queue(HPWORK,
  		   &_work,
  		   (worker_t)&LidarLitePWM::cycle_trampoline,
  		   this,
  		   getMeasureTicks());
  }
  
  int LidarLitePWM::measure()
  {
  	perf_begin(_sample_perf);
  
  	if (PX4_OK != collect()) {
  		PX4_DEBUG("collection error");
  		perf_count(_read_errors);
  		perf_end(_sample_perf);
  		return PX4_ERROR;
  	}
  
  	_range.timestamp = hrt_absolute_time();
  	_range.type = distance_sensor_s::MAV_DISTANCE_SENSOR_LASER;
  	_range.max_distance = get_maximum_distance();
  	_range.min_distance = get_minimum_distance();
  	_range.current_distance = float(_pwm.pulse_width) * 1e-3f;   /* 10 usec = 1 cm distance for LIDAR-Lite */
  	_range.covariance = 0.0f;
  	_range.orientation = _rotation;
  	/* TODO: set proper ID */
  	_range.id = 0;
  
  	/* Due to a bug in older versions of the LidarLite firmware, we have to reset sensor on (distance == 0) */
  	if (_range.current_distance <= 0.0f) {
  		perf_count(_sensor_zero_resets);
  		perf_end(_sample_perf);
  		return reset_sensor();
  	}
  
  	if (_distance_sensor_topic != nullptr) {
  		orb_publish(ORB_ID(distance_sensor), _distance_sensor_topic, &_range);
  	}
  
  	_reports->force(&_range);
  
  	poll_notify(POLLIN);
  	perf_end(_sample_perf);
  	return PX4_OK;
  }
  
  ssize_t LidarLitePWM::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 (getMeasureTicks() > 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;
  
  	} else {
  
  		_reports->flush();
  		measure();
  
  		if (_reports->get(rbuf)) {
  			ret = sizeof(*rbuf);
  		}
  	}
  
  	return ret;
  }
  
  int
  LidarLitePWM::ioctl(device::file_t *filp, int cmd, unsigned long arg)
  {
  	switch (cmd) {
  	/* no custom ioctls implemented for now */
  	default:
  		/* give it to the superclass */
  		return LidarLite::ioctl(filp, cmd, arg);
  	}
  }
  
  int LidarLitePWM::collect()
  {
  	int fd = ::open(PWMIN0_DEVICE_PATH, O_RDONLY);
  
  	if (fd == -1) {
  		return PX4_ERROR;
  	}
  
  	if (::read(fd, &_pwm, sizeof(_pwm)) == sizeof(_pwm)) {
  		::close(fd);
  		return PX4_OK;
  	}
  
  	::close(fd);
  	return EAGAIN;
  }
  
  int LidarLitePWM::reset_sensor()
  {
  
  	int fd = ::open(PWMIN0_DEVICE_PATH, O_RDONLY);
  
  	if (fd == -1) {
  		return PX4_ERROR;
  	}
  
  	int ret = ::ioctl(fd, SENSORIOCRESET, 0);
  	::close(fd);
  	return ret;
  }
  
  const char *LidarLitePWM::get_dev_name()
  {
  	return get_devname();
  }
  