hmc5883_spi.cpp

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/**
 * @file HMC5883_SPI.cpp
 *
 * SPI interface for HMC5983
 */

#include <px4_platform_common/px4_config.h>
#include <drivers/device/spi.h>
#include <drivers/drv_mag.h>
#include <drivers/drv_device.h>

#include "hmc5883.h"

#ifdef PX4_SPIDEV_HMC

/* SPI protocol address bits */
#define DIR_READ            (1<<7)
#define DIR_WRITE           (0<<7)
#define ADDR_INCREMENT          (1<<6)

#define HMC_MAX_SEND_LEN        4
#define HMC_MAX_RCV_LEN         8

device::Device *HMC5883_SPI_interface(int bus);

class HMC5883_SPI : public device::SPI
{
public:
    HMC5883_SPI(int bus, uint32_t device);
    virtual ~HMC5883_SPI() = default;

    virtual int init();
    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);

};

device::Device *
HMC5883_SPI_interface(int bus)
{
    return new HMC5883_SPI(bus, PX4_SPIDEV_HMC);
}

HMC5883_SPI::HMC5883_SPI(int bus, uint32_t device) :
    SPI("HMC5883_SPI", nullptr, bus, device, SPIDEV_MODE3, 11 * 1000 * 1000 /* will be rounded to 10.4 MHz */)
{
    _device_id.devid_s.devtype = DRV_MAG_DEVTYPE_HMC5883;
}

int
HMC5883_SPI::init()
{
    int ret;

    ret = SPI::init();

    if (ret != OK) {
        DEVICE_DEBUG("SPI init failed");
        return -EIO;
    }

    // read WHO_AM_I value
    uint8_t data[3] = {0, 0, 0};

    if (read(ADDR_ID_A, &data[0], 1) ||
        read(ADDR_ID_B, &data[1], 1) ||
        read(ADDR_ID_C, &data[2], 1)) {
        DEVICE_DEBUG("read_reg fail");
    }

    if ((data[0] != ID_A_WHO_AM_I) ||
        (data[1] != ID_B_WHO_AM_I) ||
        (data[2] != ID_C_WHO_AM_I)) {
        DEVICE_DEBUG("ID byte mismatch (%02x,%02x,%02x)", data[0], data[1], data[2]);
        return -EIO;
    }

    return OK;
}

int
HMC5883_SPI::ioctl(unsigned operation, unsigned &arg)
{
    int ret;

    switch (operation) {

    case MAGIOCGEXTERNAL:
        /*
         * Even if this sensor is on the external SPI
         * bus it is still internal to the autopilot
         * assembly, so always return 0 for internal.
         */
        return 0;

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

    default: {
            ret = -EINVAL;
        }
    }

    return ret;
}

int
HMC5883_SPI::write(unsigned address, void *data, unsigned count)
{
    uint8_t buf[32];

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

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

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

int
HMC5883_SPI::read(unsigned address, void *data, unsigned count)
{
    uint8_t buf[32];

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

    buf[0] = address | DIR_READ | ADDR_INCREMENT;

    int ret = transfer(&buf[0], &buf[0], count + 1);
    memcpy(data, &buf[1], count);
    return ret;
}

#endif /* PX4_SPIDEV_HMC */