PX4-Autopilot/src/modules/uavcan/sensors/mag.cpp

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/**
 * @author Pavel Kirienko <pavel.kirienko@gmail.com>
 */

#include "mag.hpp"

#include <drivers/drv_hrt.h>
#include <systemlib/err.h>

const char *const UavcanMagnetometerBridge::NAME = "mag";

UavcanMagnetometerBridge::UavcanMagnetometerBridge(uavcan::INode &node) :
	UavcanCDevSensorBridgeBase("uavcan_mag", "/dev/uavcan/mag", MAG_BASE_DEVICE_PATH, ORB_ID(sensor_mag)),
	_sub_mag(node)
{
	_device_id.devid_s.devtype = DRV_MAG_DEVTYPE_HMC5883;     // <-- Why?

	_scale.x_scale = 1.0F;
	_scale.y_scale = 1.0F;
	_scale.z_scale = 1.0F;
}

int UavcanMagnetometerBridge::init()
{
	int res = device::CDev::init();

	if (res < 0) {
		return res;
	}

	res = _sub_mag.start(MagCbBinder(this, &UavcanMagnetometerBridge::mag_sub_cb));

	if (res < 0) {
		DEVICE_LOG("failed to start uavcan sub: %d", res);
		return res;
	}

	return 0;
}

ssize_t UavcanMagnetometerBridge::read(struct file *filp, char *buffer, size_t buflen)
{
	static uint64_t last_read = 0;
	struct mag_report *mag_buf = reinterpret_cast<struct mag_report *>(buffer);

	/* buffer must be large enough */
	unsigned count = buflen / sizeof(struct mag_report);

	if (count < 1) {
		return -ENOSPC;
	}

	if (last_read < _report.timestamp) {
		/* copy report */
		lock();
		*mag_buf = _report;
		last_read = _report.timestamp;
		unlock();
		return sizeof(struct mag_report);

	} else {
		/* no new data available, warn caller */
		return -EAGAIN;
	}
}

int UavcanMagnetometerBridge::ioctl(struct file *filp, int cmd, unsigned long arg)
{
	switch (cmd) {
	case SENSORIOCSQUEUEDEPTH: {
			return OK;			// Pretend that this stuff is supported to keep APM happy
		}

	case MAGIOCSSCALE: {
			std::memcpy(&_scale, reinterpret_cast<const void *>(arg), sizeof(_scale));
			return 0;
		}

	case MAGIOCGSCALE: {
			std::memcpy(reinterpret_cast<void *>(arg), &_scale, sizeof(_scale));
			return 0;
		}

	case MAGIOCSELFTEST: {
			return 0;           // Nothing to do
		}

	case MAGIOCGEXTERNAL: {
			return 1;           // declare it external rise it's priority and to allow for correct orientation compensation
		}

	case MAGIOCSSAMPLERATE: {
			return 0;           // Pretend that this stuff is supported to keep the sensor app happy
		}

	case MAGIOCCALIBRATE:
	case MAGIOCGSAMPLERATE:
	case MAGIOCSRANGE:
	case MAGIOCGRANGE:
	case MAGIOCEXSTRAP: {
			return -EINVAL;
		}

	default: {
			return CDev::ioctl(filp, cmd, arg);
		}
	}
}

void UavcanMagnetometerBridge::mag_sub_cb(const
		uavcan::ReceivedDataStructure<uavcan::equipment::ahrs::MagneticFieldStrength>
		&msg)
{
	lock();
	_report.range_ga = 1.3F;   // Arbitrary number, doesn't really mean anything
	/*
	 * FIXME HACK
	 * This code used to rely on msg.getMonotonicTimestamp().toUSec() instead of HRT.
	 * It stopped working when the time sync feature has been introduced, because it caused libuavcan
	 * to use an independent time source (based on hardware TIM5) instead of HRT.
	 * The proper solution is to be developed.
	 */
	_report.timestamp = hrt_absolute_time();
	_report.device_id = _device_id.devid;
	_report.is_external = true;

	_report.x = (msg.magnetic_field_ga[0] - _scale.x_offset) * _scale.x_scale;
	_report.y = (msg.magnetic_field_ga[1] - _scale.y_offset) * _scale.y_scale;
	_report.z = (msg.magnetic_field_ga[2] - _scale.z_offset) * _scale.z_scale;
	unlock();

	publish(msg.getSrcNodeID().get(), &_report);
}