qmc5883_i2c.cpp

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/**
 * @file QMC5883_I2C.cpp
 *
 * I2C interface for QMC5883
 */

/* XXX trim includes */
#include <px4_platform_common/px4_config.h>

#include <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <assert.h>
#include <debug.h>
#include <errno.h>
#include <unistd.h>

#include <arch/board/board.h>

#include <drivers/device/i2c.h>
#include <drivers/drv_mag.h>
#include <drivers/drv_device.h>

#include "qmc5883.h"

#include "board_config.h"

#define QMC5883L_ADDRESS        0x0D

device::Device *QMC5883_I2C_interface(int bus);

class QMC5883_I2C : public device::I2C
{
public:
    QMC5883_I2C(int bus);
    virtual ~QMC5883_I2C() = default;

    virtual int read(unsigned address, void *data, unsigned count);
    virtual int write(unsigned address, void *data, unsigned count);

    virtual int ioctl(unsigned operation, unsigned &arg);

protected:
    virtual int probe();

};

device::Device *
QMC5883_I2C_interface(int bus)
{
    return new QMC5883_I2C(bus);
}

QMC5883_I2C::QMC5883_I2C(int bus) :
    I2C("QMC5883_I2C", nullptr, bus, QMC5883L_ADDRESS, 400000)
{
    _device_id.devid_s.devtype = DRV_MAG_DEVTYPE_QMC5883;
}

int
QMC5883_I2C::ioctl(unsigned operation, unsigned &arg)
{
    int ret;

    switch (operation) {

    case MAGIOCGEXTERNAL:
        return external();

    case DEVIOCGDEVICEID:
        return CDev::ioctl(nullptr, operation, arg);

    default:
        ret = -EINVAL;
    }

    return ret;
}

int
QMC5883_I2C::probe()
{
    uint8_t data[2] = {0, 0};

    // must read registers 0x00 once or reset to read ID registers reliably
    read(0x00, &data[0], 1);
    read(0x00, &data[0], 1);
    read(0x00, &data[0], 1);

    _retries = 10;

    bool read_valid = false;
    bool id_valid = false;

    for (unsigned i = 0; i < _retries; i++) {
        //attempt read
        if (!read(ADDR_ID_A, &data[0], 1) &&
            !read(ADDR_ID_B, &data[1], 1)) {
            read_valid = true;
        }

        if (read_valid && data[0] == ID_A_WHO_AM_I &&
            data[1] == ID_B_WHO_AM_I) {
            id_valid = true;
        }

        if (read_valid && id_valid) {
            return OK;
        }

        // wait 100 usec
        usleep(100);
    }

    if (!read_valid) {
        DEVICE_DEBUG("read_reg fail");
    }

    if (!id_valid) {
        DEVICE_DEBUG("ID byte mismatch (%02x,%02x)", data[0], data[1]);
    }

    return -EIO;
}

int
QMC5883_I2C::write(unsigned address, void *data, unsigned count)
{
    uint8_t buf[32];

    if (sizeof(buf) < (count + 1)) {
        return -EIO;
    }

    buf[0] = address;
    memcpy(&buf[1], data, count);

    return transfer(&buf[0], count + 1, nullptr, 0);
}

int
QMC5883_I2C::read(unsigned address, void *data, unsigned count)
{
    uint8_t cmd = address;
    return transfer(&cmd, 1, (uint8_t *)data, count);
}