rm3100_i2c.cpp

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/**
 * @file rm3100_i2c.cpp
 *
 * I2C interface for RM3100
 */

#include <px4_platform_common/px4_config.h>

#include <assert.h>
#include <debug.h>
#include <errno.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <sys/types.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 "board_config.h"
#include "rm3100.h"

#if defined(PX4_I2C_BUS_ONBOARD) || defined(PX4_I2C_BUS_EXPANSION)

#define RM3100_ADDRESS      0x20

class RM3100_I2C : public device::I2C
{
public:
    RM3100_I2C(int bus);
    virtual ~RM3100_I2C() = default;

    virtual int     init();
    virtual int     ioctl(unsigned operation, unsigned &arg);
    virtual int     read(unsigned address, void *data, unsigned count);
    virtual int     write(unsigned address, void *data, unsigned count);

protected:
    virtual int     probe();

};

device::Device *
RM3100_I2C_interface(int bus);

device::Device *
RM3100_I2C_interface(int bus)
{
    return new RM3100_I2C(bus);
}

RM3100_I2C::RM3100_I2C(int bus) :
    I2C("RM300_I2C", nullptr, bus, RM3100_ADDRESS, 400000)
{
    _device_id.devid_s.devtype = DRV_MAG_DEVTYPE_RM3100;
}

int
RM3100_I2C::init()
{
    /* this will call probe() */
    return I2C::init();
}

int
RM3100_I2C::ioctl(unsigned operation, unsigned &arg)
{
    switch (operation) {

    case MAGIOCGEXTERNAL:
        return external();

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

    default:
        return  -EINVAL;
    }
}

int
RM3100_I2C::probe()
{
    uint8_t data = 0;

    _retries = 10;

    if (read(ADDR_REVID, &data, 1)) {
        DEVICE_DEBUG("RM3100 read_reg fail");
        return -EIO;
    }

    _retries = 2;

    if (data != RM3100_REVID) {
        DEVICE_DEBUG("RM3100 bad ID: %02x", data);
        return -EIO;
    }

    return OK;
}

int
RM3100_I2C::read(unsigned address, void *data, unsigned count)
{
    uint8_t cmd = address;
    int ret;

    /* We need a first transfer where we write the register to read */
    ret = transfer(&cmd, 1, nullptr, 0);

    if (ret != OK) {
        return ret;
    }

    /* Now we read the previously selected register */
    ret = transfer(nullptr, 0, (uint8_t *)data, count);

    return ret;
}

int
RM3100_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);
}

#endif /* PX4_I2C_OBDEV_RM3100 */