mpl3115a2.cpp

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 *
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 * modification, are permitted provided that the following conditions
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 *
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 *    used to endorse or promote products derived from this software
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/**
 * @file mpl3115a2.cpp
 *
 * Driver for the MPL3115A2 barometric pressure sensor connected via I2C.
 */

#include "mpl3115a2.h"

enum MPL3115A2_BUS {
    MPL3115A2_BUS_ALL = 0,
    MPL3115A2_BUS_I2C_INTERNAL,
    MPL3115A2_BUS_I2C_EXTERNAL,
};

/* helper macro for handling report buffer indices */
#define INCREMENT(_x, _lim) do { __typeof__(_x) _tmp = _x+1; if (_tmp >= _lim) _tmp = 0; _x = _tmp; } while(0)

/* helper macro for arithmetic - returns the square of the argument */
#define POW2(_x)        ((_x) * (_x))

/*
 * MPL3115A2 internal constants and data structures.
 */

#define MPL3115A2_CONVERSION_INTERVAL   10000   /* microseconds */
#define MPL3115A2_OSR                   2       /* Over Sample rate of 4 18MS Minimum time between data samples */
#define MPL3115A2_CTRL_TRIGGER          (CTRL_REG1_OST | CTRL_REG1_OS(MPL3115A2_OSR))
#define MPL3115A2_BARO_DEVICE_PATH_EXT  "/dev/mpl3115a2_ext"
#define MPL3115A2_BARO_DEVICE_PATH_INT  "/dev/mpl3115a2_int"

class MPL3115A2 : public cdev::CDev, public px4::ScheduledWorkItem
{
public:
    MPL3115A2(device::Device *interface, const char *path);
    ~MPL3115A2();

    virtual int     init();

    virtual ssize_t     read(struct file *filp, char *buffer, size_t buflen);
    virtual int     ioctl(struct file *filp, int cmd, unsigned long arg);

    /**
     * Diagnostics - print some basic information about the driver.
     */
    void            print_info();

protected:
    device::Device          *_interface;

    unsigned        _measure_interval;

    ringbuffer::RingBuffer  *_reports;
    bool            _collect_phase;

    /*  */
    float           _P;
    float           _T;

    orb_advert_t        _baro_topic;
    int         _orb_class_instance;
    int         _class_instance;

    perf_counter_t      _sample_perf;
    perf_counter_t      _measure_perf;
    perf_counter_t      _comms_errors;

    /**
     * Initialize the automatic measurement state machine and start it.
     *
     * @param delay_us the number of microseconds before executing the next cycle
     *
     * @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(unsigned delay_us = 1);

    /**
     * Stop the automatic measurement state machine.
     */
    void            stop();

    /**
     * Perform a poll cycle; collect from the previous measurement
     * and start a new one.
     *
     * This is the heart of the measurement state machine.  This function
     * alternately starts a measurement, or collects the data from the
     * previous measurement.
     *
     * When the interval between measurements is greater than the minimum
     * measurement interval, a gap is inserted between collection
     * and measurement to provide the most recent measurement possible
     * at the next interval.
     */
    void            Run() override;

    /**
     * Issue a measurement command for the current state.
     *
     * @return      OK if the measurement command was successful.
     */
    virtual int     measure();

    /**
     * Collect the result of the most recent measurement.
     */
    virtual int     collect();

};

/*
 * Driver 'main' command.
 */
extern "C" __EXPORT int mpl3115a2_main(int argc, char *argv[]);

MPL3115A2::MPL3115A2(device::Device *interface, const char *path) :
    CDev(path),
    ScheduledWorkItem(MODULE_NAME, px4::device_bus_to_wq(interface->get_device_id())),
    _interface(interface),
    _measure_interval(0),
    _reports(nullptr),
    _collect_phase(false),
    _P(0),
    _T(0),
    _baro_topic(nullptr),
    _orb_class_instance(-1),
    _class_instance(-1),
    _sample_perf(perf_alloc(PC_ELAPSED, "mpl3115a2_read")),
    _measure_perf(perf_alloc(PC_ELAPSED, "mpl3115a2_measure")),
    _comms_errors(perf_alloc(PC_COUNT, "mpl3115a2_com_err"))
{
    _interface->set_device_type(DRV_BARO_DEVTYPE_MPL3115A2);
}

MPL3115A2::~MPL3115A2()
{
    /* make sure we are truly inactive */
    stop();

    if (_class_instance != -1) {
        unregister_class_devname(get_devname(), _class_instance);
    }

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

    // free perf counters
    perf_free(_sample_perf);
    perf_free(_measure_perf);
    perf_free(_comms_errors);

    delete _interface;
}

int
MPL3115A2::init()
{
    int ret;

    ret = CDev::init();

    if (ret != OK) {
        PX4_DEBUG("CDev init failed");
        goto out;
    }

    /* allocate basic report buffers */
    _reports = new ringbuffer::RingBuffer(2, sizeof(sensor_baro_s));

    if (_reports == nullptr) {
        PX4_DEBUG("can't get memory for reports");
        ret = -ENOMEM;
        goto out;
    }

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

    sensor_baro_s brp;
    _reports->flush();

    while (true) {

        /* First reading */
        do  {
            ret = measure();

            if (ret == -EAGAIN) {
                usleep(500);
            }
        } while (ret == -EAGAIN);

        if (ret != OK) {
            ret = -EIO;
            break;
        }

        /* First reading */
        do  {
            ret = collect();

            if (ret == -EAGAIN) {
                usleep(500);
            }
        } while (ret == -EAGAIN);

        if (ret != OK) {
            ret = -EIO;
            break;
        }

        /* state machine will have generated a report, copy it out */
        _reports->get(&brp);

        // DEVICE_LOG("altitude (%u) = %.2f", _device_type, (double)brp.altitude);

        /* ensure correct devid */
        brp.device_id = _interface->get_device_id();

        ret = OK;

        _baro_topic = orb_advertise_multi(ORB_ID(sensor_baro), &brp,
                          &_orb_class_instance, (_interface->external()) ? ORB_PRIO_HIGH : ORB_PRIO_DEFAULT);

        if (_baro_topic == nullptr) {
            warnx("failed to create sensor_baro publication");
        }

        break;
    }

out:
    return ret;
}

ssize_t
MPL3115A2::read(struct file *filp, char *buffer, size_t buflen)
{
    unsigned count = buflen / sizeof(sensor_baro_s);
    sensor_baro_s *brp = reinterpret_cast<sensor_baro_s *>(buffer);
    int ret = 0;

    /* buffer must be large enough */
    if (count < 1) {
        return -ENOSPC;
    }

    /* if automatic measurement is enabled */
    if (_measure_interval > 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(brp)) {
                ret += sizeof(*brp);
                brp++;
            }
        }

        /* if there was no data, warn the caller */
        return ret ? ret : -EAGAIN;
    }

    /* manual measurement - run one conversion */
    do {
        _reports->flush();

        /* First reading */
        do  {
            ret = measure();

            if (ret == -EAGAIN) {
                usleep(1000);
            }
        } while (ret == -EAGAIN);

        if (ret != OK) {
            ret = -EIO;
            break;
        }

        if (OK != collect()) {
            ret = -EIO;
            break;
        }

        /* state machine will have generated a report, copy it out */
        if (_reports->get(brp)) {
            ret = sizeof(*brp);
        }

    } while (0);

    return ret;
}

int
MPL3115A2::ioctl(struct file *filp, int cmd, unsigned long arg)
{
    switch (cmd) {

    case SENSORIOCSPOLLRATE: {
            switch (arg) {

            /* zero would be bad */
            case 0:
                return -EINVAL;

            /* set default polling rate */
            case SENSOR_POLLRATE_DEFAULT: {
                    /* do we need to start internal polling? */
                    bool want_start = (_measure_interval == 0);

                    /* set interval for next measurement to minimum legal value */
                    _measure_interval = MPL3115A2_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_interval == 0);

                    /* convert hz to tick interval via microseconds */
                    unsigned interval = (1000000 / arg);

                    /* check against maximum rate */
                    if (interval < MPL3115A2_CONVERSION_INTERVAL) {
                        return -EINVAL;
                    }

                    /* update interval for next measurement */
                    _measure_interval = interval;

                    /* if we need to start the poll state machine, do it */
                    if (want_start) {
                        start();
                    }

                    return OK;
                }
            }
        }

    case SENSORIOCRESET: {
            /*
             * Since we are initialized, we do not need to do anything, since the
             * PROM is correctly read and the part does not need to be configured.
             */
            unsigned int dummy;
            _interface->ioctl(IOCTL_RESET, dummy);
            return OK;
        }

    default:
        break;
    }

    /* give it to the bus-specific superclass */
    // return bus_ioctl(filp, cmd, arg);
    return CDev::ioctl(filp, cmd, arg);
}

void
MPL3115A2::start(unsigned delay_us)
{
    /* reset the report ring and state machine */
    _collect_phase = false;
    _reports->flush();

    /* schedule a cycle to start things */
    ScheduleDelayed(delay_us);
}

void
MPL3115A2::stop()
{
    ScheduleClear();
}

void
MPL3115A2::Run()
{
    int ret;
    unsigned dummy;

    /* collection phase? */
    if (_collect_phase) {

        /* perform collection */
        ret = collect();

        if (ret == -EIO) {
            /* issue a reset command to the sensor */
            _interface->ioctl(IOCTL_RESET, dummy);
            /* reset the collection state machine and try again - we need
             * to wait 2.8 ms after issuing the sensor reset command
             * according to the MPL3115A2 datasheet
             */
            start(2800);
            return;
        }

        if (ret == -EAGAIN) {

            /* Ready read it on next cycle */
            ScheduleDelayed(MPL3115A2_CONVERSION_INTERVAL);

            return;
        }

        /* next phase is measurement */
        _collect_phase = false;
    }

    /* Look for a ready condition */

    ret = measure();

    if (ret == -EIO) {
        /* issue a reset command to the sensor */
        _interface->ioctl(IOCTL_RESET, dummy);
        /* reset the collection state machine and try again */
        start();
        return;
    }

    /* next phase is measurement */
    _collect_phase = true;

    /* schedule a fresh cycle call when the measurement is done */
    ScheduleDelayed(MPL3115A2_CONVERSION_INTERVAL);
}

int
MPL3115A2::measure()
{
    int ret;

    perf_begin(_measure_perf);

    /*
     * Send the command to read the ADC for P and T.
     */
    unsigned addr = (MPL3115A2_CTRL_REG1 << 8) | MPL3115A2_CTRL_TRIGGER;
    ret = _interface->ioctl(IOCTL_MEASURE, addr);

    if (ret == -EIO) {
        perf_count(_comms_errors);
    }

    perf_end(_measure_perf);

    return PX4_OK;
}

int
MPL3115A2::collect()
{
    int ret;
    MPL3115A2_data_t reading;
    uint8_t ctrl;

    perf_begin(_sample_perf);

    ret = _interface->read(MPL3115A2_CTRL_REG1, (void *)&ctrl, 1);

    if (ret == -EIO) {
        perf_end(_sample_perf);
        return ret;
    }

    if (ctrl & CTRL_REG1_OST) {
        perf_end(_sample_perf);
        return -EAGAIN;
    }

    sensor_baro_s report;

    /* this should be fairly close to the end of the conversion, so the best approximation of the time */
    report.timestamp = hrt_absolute_time();

    report.error_count = perf_event_count(_comms_errors);

    /* read the most recent measurement - read offset/size are hardcoded in the interface */
    ret = _interface->read(OUT_P_MSB, (void *)&reading, sizeof(reading));

    if (ret == -EIO) {
        perf_count(_comms_errors);
        perf_end(_sample_perf);
        return ret;
    }

    _T = (float) reading.temperature.b[1] + ((float)(reading.temperature.b[0]) / 16.0f);
    _P = (float)(reading.pressure.q >> 8) + ((float)(reading.pressure.b[0]) / 4.0f);

    report.temperature = _T;
    report.pressure = _P / 100.0f;      /* convert to millibar */

    /* return device ID */
    report.device_id = _interface->get_device_id();

    /* publish it */
    if (_baro_topic != nullptr) {
        /* publish it */
        orb_publish(ORB_ID(sensor_baro), _baro_topic, &report);
    }

    _reports->force(&report);

    /* notify anyone waiting for data */
    poll_notify(POLLIN);

    perf_end(_sample_perf);

    return OK;
}

void
MPL3115A2::print_info()
{
    perf_print_counter(_sample_perf);
    perf_print_counter(_comms_errors);
    printf("poll interval:  %u\n", _measure_interval);
    _reports->print_info("report queue");

    sensor_baro_s brp = {};
    _reports->get(&brp);
    print_message(brp);
}

/**
 * Local functions in support of the shell command.
 */
namespace mpl3115a2
{

/*
  list of supported bus configurations
 */
struct mpl3115a2_bus_option {
    enum MPL3115A2_BUS busid;
    const char *devpath;
    MPL3115A2_constructor interface_constructor;
    uint8_t busnum;
    MPL3115A2 *dev;
} bus_options[] = {
#if defined(PX4_SPIDEV_EXT_BARO) && defined(PX4_SPI_BUS_EXT)
    { MPL3115A2_BUS_SPI_EXTERNAL, "/dev/mpl3115a2_spi_ext", &MPL3115A2_spi_interface, PX4_SPI_BUS_EXT, NULL },
#endif
#ifdef PX4_SPIDEV_BARO
    { MPL3115A2_BUS_SPI_INTERNAL, "/dev/mpl3115a2_spi_int", &MPL3115A2_spi_interface, PX4_SPI_BUS_BARO, NULL },
#endif
#ifdef PX4_I2C_BUS_ONBOARD
    { MPL3115A2_BUS_I2C_INTERNAL, "/dev/mpl3115a2_int", &MPL3115A2_i2c_interface, PX4_I2C_BUS_ONBOARD, NULL },
#endif
#ifdef PX4_I2C_BUS_EXPANSION
    { MPL3115A2_BUS_I2C_EXTERNAL, "/dev/mpl3115a2_ext", &MPL3115A2_i2c_interface, PX4_I2C_BUS_EXPANSION, NULL },
#endif
#ifdef PX4_I2C_BUS_EXPANSION1
    { MPL3115A2_BUS_I2C_EXTERNAL, "/dev/mpl3115a2_ext1", &MPL3115A2_i2c_interface, PX4_I2C_BUS_EXPANSION1, NULL },
#endif
#ifdef PX4_I2C_BUS_EXPANSION2
    { MPL3115A2_BUS_I2C_EXTERNAL, "/dev/mpl3115a2_ext2", &MPL3115A2_i2c_interface, PX4_I2C_BUS_EXPANSION2, NULL },
#endif
};
#define NUM_BUS_OPTIONS (sizeof(bus_options)/sizeof(bus_options[0]))

bool    start_bus(struct mpl3115a2_bus_option &bus);
struct mpl3115a2_bus_option &find_bus(enum MPL3115A2_BUS busid);
void    start(enum MPL3115A2_BUS busid);
void    test(enum MPL3115A2_BUS busid);
void    reset(enum MPL3115A2_BUS busid);
void    info();
void    usage();

/**
 * Start the driver.
 */
bool
start_bus(struct mpl3115a2_bus_option &bus)
{
    if (bus.dev != nullptr) {
        errx(1, "bus option already started");
    }

    device::Device *interface = bus.interface_constructor(bus.busnum);

    if (interface->init() != OK) {
        delete interface;
        warnx("no device on bus %u", (unsigned)bus.busid);
        return false;
    }

    bus.dev = new MPL3115A2(interface, bus.devpath);

    if (bus.dev != nullptr && OK != bus.dev->init()) {
        delete bus.dev;
        bus.dev = NULL;
        return false;
    }

    int fd = open(bus.devpath, O_RDONLY);

    /* set the poll rate to default, starts automatic data collection */
    if (fd == -1) {
        errx(1, "can't open baro device");
    }

    if (ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT) < 0) {
        close(fd);
        errx(1, "failed setting default poll rate");
    }

    close(fd);
    return true;
}


/**
 * Start the driver.
 *
 * This function call only returns once the driver
 * is either successfully up and running or failed to start.
 */
void
start(enum MPL3115A2_BUS busid)
{
    uint8_t i;
    bool started = false;

    for (i = 0; i < NUM_BUS_OPTIONS; i++) {
        if (busid == MPL3115A2_BUS_ALL && bus_options[i].dev != NULL) {
            // this device is already started
            continue;
        }

        if (busid != MPL3115A2_BUS_ALL && bus_options[i].busid != busid) {
            // not the one that is asked for
            continue;
        }

        started = started | start_bus(bus_options[i]);
    }

    if (!started) {
        exit(1);
    }

    // one or more drivers started OK
    exit(0);
}


/**
 * find a bus structure for a busid
 */
struct mpl3115a2_bus_option &find_bus(enum MPL3115A2_BUS busid)
{
    for (uint8_t i = 0; i < NUM_BUS_OPTIONS; i++) {
        if ((busid == MPL3115A2_BUS_ALL ||
             busid == bus_options[i].busid) && bus_options[i].dev != NULL) {
            return bus_options[i];
        }
    }

    errx(1, "bus %u not started", (unsigned)busid);
}

/**
 * Perform some basic functional tests on the driver;
 * make sure we can collect data from the sensor in polled
 * and automatic modes.
 */
void
test(enum MPL3115A2_BUS busid)
{
    struct mpl3115a2_bus_option &bus = find_bus(busid);
    sensor_baro_s report;
    ssize_t sz;
    int ret;

    int fd;

    fd = open(bus.devpath, O_RDONLY);

    if (fd < 0) {
        err(1, "open failed (try 'mpl3115a2 start' if the driver is not running)");
    }

    /* do a simple demand read */
    sz = read(fd, &report, sizeof(report));

    if (sz != sizeof(report)) {
        err(1, "immediate read failed");
    }

    print_message(report);

    /* 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;
        ret = poll(&fds, 1, 2000);

        if (ret != 1) {
            errx(1, "timed out waiting for sensor data");
        }

        /* now go get it */
        sz = read(fd, &report, sizeof(report));

        if (sz != sizeof(report)) {
            err(1, "periodic read failed");
        }

        print_message(report);
    }

    close(fd);
    errx(0, "PASS");
}

/**
 * Reset the driver.
 */
void
reset(enum MPL3115A2_BUS busid)
{
    struct mpl3115a2_bus_option &bus = find_bus(busid);
    int fd;

    fd = open(bus.devpath, 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()
{
    for (uint8_t i = 0; i < NUM_BUS_OPTIONS; i++) {
        struct mpl3115a2_bus_option &bus = bus_options[i];

        if (bus.dev != nullptr) {
            warnx("%s", bus.devpath);
            bus.dev->print_info();
        }
    }

    exit(0);
}

void
usage()
{
    warnx("missing command: try 'start', 'info', 'test', 'reset'");
    warnx("options:");
    warnx("    -X    (external I2C bus)");
    warnx("    -I    (intternal I2C bus)");

}

} // namespace

int
mpl3115a2_main(int argc, char *argv[])
{
    enum MPL3115A2_BUS busid = MPL3115A2_BUS_ALL;
    int myoptind = 1;
    int ch;
    const char *myoptarg = NULL;

    /* jump over start/off/etc and look at options first */
    while ((ch = px4_getopt(argc, argv, "XI", &myoptind, &myoptarg)) != EOF) {
        switch (ch) {
        case 'X':
            busid = MPL3115A2_BUS_I2C_EXTERNAL;
            break;

        case 'I':
            busid = MPL3115A2_BUS_I2C_INTERNAL;
            break;

        default:
            mpl3115a2::usage();
            exit(0);
        }
    }

    if (myoptind >= argc) {
        mpl3115a2::usage();
        exit(0);
    }

    const char *verb = argv[myoptind];

    /*
     * Start/load the driver.
     */
    if (!strcmp(verb, "start")) {
        mpl3115a2::start(busid);
    }

    /*
     * Test the driver/device.
     */
    if (!strcmp(verb, "test")) {
        mpl3115a2::test(busid);
    }

    /*
     * Reset the driver.
     */
    if (!strcmp(verb, "reset")) {
        mpl3115a2::reset(busid);
    }

    /*
     * Print driver information.
     */
    if (!strcmp(verb, "info")) {
        mpl3115a2::info();
    }

    mpl3115a2::usage();
    exit(1);
}