PX4-Autopilot/src/drivers/airspeed/airspeed.cpp

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/**
 * @file ets_airspeed.cpp
 * @author Simon Wilks
 *
 * Driver for the Eagle Tree Airspeed V3 connected via I2C.
 */

#include <nuttx/config.h>

#include <drivers/device/i2c.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 <nuttx/arch.h>
#include <nuttx/wqueue.h>
#include <nuttx/clock.h>

#include <arch/board/board.h>

#include <systemlib/airspeed.h>
#include <systemlib/err.h>
#include <systemlib/param/param.h>
#include <systemlib/perf_counter.h>

#include <drivers/drv_airspeed.h>
#include <drivers/drv_hrt.h>
#include <drivers/device/ringbuffer.h>

#include <uORB/uORB.h>
#include <uORB/topics/differential_pressure.h>
#include <uORB/topics/subsystem_info.h>

#include <drivers/airspeed/airspeed.h>

Airspeed::Airspeed(int bus, int address, unsigned conversion_interval, const char* path) :
	I2C("Airspeed", path, bus, address, 100000),
	_reports(nullptr),
	_buffer_overflows(perf_alloc(PC_COUNT, "airspeed_buffer_overflows")),
	_max_differential_pressure_pa(0),
	_sensor_ok(false),
	_last_published_sensor_ok(true), /* initialize differently to force publication */
	_measure_ticks(0),
	_collect_phase(false),
	_diff_pres_offset(0.0f),
	_airspeed_pub(-1),
	_subsys_pub(-1),
	_class_instance(-1),
	_conversion_interval(conversion_interval),
	_sample_perf(perf_alloc(PC_ELAPSED, "airspeed_read")),
	_comms_errors(perf_alloc(PC_COUNT, "airspeed_comms_errors"))
{
	// enable debug() calls
	_debug_enabled = false;

	// work_cancel in the dtor will explode if we don't do this...
	memset(&_work, 0, sizeof(_work));
}

Airspeed::~Airspeed()
{
	/* make sure we are truly inactive */
	stop();

	if (_class_instance != -1)
		unregister_class_devname(AIRSPEED_DEVICE_PATH, _class_instance);

	/* free any existing reports */
	if (_reports != nullptr)
		delete _reports;

	// free perf counters
	perf_free(_sample_perf);
	perf_free(_comms_errors);
	perf_free(_buffer_overflows);
}

int
Airspeed::init()
{
	int ret = ERROR;

	/* do I2C init (and probe) first */
	if (I2C::init() != OK)
		goto out;

	/* allocate basic report buffers */
	_reports = new RingBuffer(2, sizeof(differential_pressure_s));
	if (_reports == nullptr)
		goto out;

	/* register alternate interfaces if we have to */
	_class_instance = register_class_devname(AIRSPEED_DEVICE_PATH);

	/* publication init */
	if (_class_instance == CLASS_DEVICE_PRIMARY) {

		/* advertise sensor topic, measure manually to initialize valid report */
		struct differential_pressure_s arp;
		measure();
		_reports->get(&arp);

		/* measurement will have generated a report, publish */
		_airspeed_pub = orb_advertise(ORB_ID(differential_pressure), &arp);

		if (_airspeed_pub < 0)
			warnx("uORB started?");
	}

	ret = OK;

out:
	return ret;
}

int
Airspeed::probe()
{
	/* on initial power up the device may need more than one retry
	   for detection. Once it is running the number of retries can
	   be reduced
	*/
	_retries = 4;
	int ret = measure();

        // drop back to 2 retries once initialised
	_retries = 2;
	return ret;
}

int
Airspeed::ioctl(struct file *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;

			irqstate_t flags = irqsave();
			if (!_reports->resize(arg)) {
				irqrestore(flags);
				return -ENOMEM;
			}
			irqrestore(flags);

			return OK;
		}

	case SENSORIOCGQUEUEDEPTH:
		return _reports->size();

	case SENSORIOCRESET:
		/* XXX implement this */
		return -EINVAL;

	case AIRSPEEDIOCSSCALE: {
		struct airspeed_scale *s = (struct airspeed_scale*)arg;
		_diff_pres_offset = s->offset_pa;
		return OK;
		}

	case AIRSPEEDIOCGSCALE: {
		struct airspeed_scale *s = (struct airspeed_scale*)arg;
		s->offset_pa = _diff_pres_offset;
		s->scale = 1.0f;
		return OK;
		}

	default:
		/* give it to the superclass */
		return I2C::ioctl(filp, cmd, arg);
	}
}

ssize_t
Airspeed::read(struct file *filp, char *buffer, size_t buflen)
{
	unsigned count = buflen / sizeof(differential_pressure_s);
	differential_pressure_s *abuf = reinterpret_cast<differential_pressure_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(abuf)) {
				ret += sizeof(*abuf);
				abuf++;
			}
		}

		/* 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(abuf)) {
			ret = sizeof(*abuf);
		}

	} while (0);

	return ret;
}

void
Airspeed::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)&Airspeed::cycle_trampoline, this, 1);
}

void
Airspeed::stop()
{
	work_cancel(HPWORK, &_work);
}

void
Airspeed::update_status()
{
	if (_sensor_ok != _last_published_sensor_ok) {
		/* notify about state change */
		struct subsystem_info_s info = {
			true,
			true,
			_sensor_ok,
			SUBSYSTEM_TYPE_DIFFPRESSURE
		};

		if (_subsys_pub > 0) {
			orb_publish(ORB_ID(subsystem_info), _subsys_pub, &info);
		} else {
			_subsys_pub = orb_advertise(ORB_ID(subsystem_info), &info);
		}

		_last_published_sensor_ok = _sensor_ok;
	}
}

void
Airspeed::cycle_trampoline(void *arg)
{
	Airspeed *dev = (Airspeed *)arg;

	dev->cycle();
	// XXX we do not know if this is
	// really helping - do not update the
	// subsys state right now
	//dev->update_status();
}

void
Airspeed::print_info()
{
	perf_print_counter(_sample_perf);
	perf_print_counter(_comms_errors);
	perf_print_counter(_buffer_overflows);
	warnx("poll interval:  %u ticks", _measure_ticks);
	_reports->print_info("report queue");
}

void
Airspeed::new_report(const differential_pressure_s &report)
{
	if (!_reports->force(&report))
		perf_count(_buffer_overflows);
}