icm20948_i2c.cpp

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/**
 * @file icm20948_i2c.cpp
 *
 * I2C interface for ICM20948
 */

#include <px4_platform_common/px4_config.h>
#include <drivers/device/i2c.h>
#include <drivers/drv_device.h>

#include "icm20948.h"

#ifdef USE_I2C

device::Device *ICM20948_I2C_interface(int bus, uint32_t address);

class ICM20948_I2C : public device::I2C
{
public:
    ICM20948_I2C(int bus, uint32_t address);
    ~ICM20948_I2C() override = default;

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

protected:
    virtual int probe();

private:

};

device::Device *
ICM20948_I2C_interface(int bus, uint32_t address)
{
    return new ICM20948_I2C(bus, address);
}

ICM20948_I2C::ICM20948_I2C(int bus, uint32_t address) :
    I2C("ICM20948_I2C", nullptr, bus, address, 400000)
{
    _device_id.devid_s.devtype = DRV_DEVTYPE_ICM20948;
}

int
ICM20948_I2C::write(unsigned reg_speed, void *data, unsigned count)
{
    uint8_t cmd[2] {};

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

    cmd[0] = ICM20948_REG(reg_speed);
    cmd[1] = *(uint8_t *)data;
    return transfer(&cmd[0], count + 1, nullptr, 0);
}

int
ICM20948_I2C::read(unsigned reg_speed, void *data, unsigned count)
{
    /* We want to avoid copying the data of MPUReport: So if the caller
     * supplies a buffer not MPUReport in size, it is assume to be a reg or
     * reg 16 read
     * Since MPUReport has a cmd at front, we must return the data
     * after that. Foe anthing else we must return it
     */
    uint32_t offset = count < sizeof(MPUReport) ? 0 : offsetof(MPUReport, status);
    uint8_t cmd = ICM20948_REG(reg_speed);
    return transfer(&cmd, 1, &((uint8_t *)data)[offset], count);
}

int
ICM20948_I2C::probe()
{
    uint8_t whoami = 0;
    uint8_t register_select = REG_BANK(BANK0);  // register bank containing WHOAMI for ICM20948

    // Try first for icm20948/6500
    read(MPUREG_WHOAMI, &whoami, 1);

    /*
     * If it's not an MPU it must be an ICM
     * Make sure register bank 0 is selected - whoami is only present on bank 0, and that is
     * not sure e.g. if the device has rebooted without repowering the sensor
     */
    write(ICMREG_20948_BANK_SEL, &register_select, 1);
    read(ICMREG_20948_WHOAMI, &whoami, 1);

    if (whoami == ICM_WHOAMI_20948) {
        return PX4_OK;
    }

    return -ENODEV;
}

#endif /* USE_I2C */