MPU6000_SPI.cpp

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/**
 * @file mpu6000_spi.cpp
 *
 * Driver for the Invensense MPU6000 connected via SPI.
 *
 * @author Andrew Tridgell
 * @author Pat Hickey
 * @author David sidrane
 */

#include <drivers/device/spi.h>

#include "MPU6000.hpp"

#define DIR_READ            0x80
#define DIR_WRITE           0x00

#if defined(PX4_SPIDEV_MPU) || defined(PX4_SPIDEV_ICM_20602) || defined(PX4_SPIDEV_ICM_20689)

/* The MPU6000 can only handle high SPI bus speeds of 20Mhz on the sensor and
* interrupt status registers. All other registers have a maximum 1MHz
* SPI speed
*
* The ICM parts are not rated as high.
*
* The Actual Value will be rounded down by the spi driver.
*          168 Mhz CPU         180 Mhz CPU
* Selected ------------actual---------------
* 20 Mhz   10.5     Mhz         11.250   Mhz
* 10 Mhz   5.250    Mhz         5.625    Mhz
* 8  Mhz   5.250    Mhz         5.625    Mhz
* 1  Mhz   0.703125 Mhz         0.65625  Mhz
*
*/
#define MPU6000_LOW_SPI_BUS_SPEED    1000*1000
#define MPU6000_HIGH_SPI_BUS_SPEED   20*1000*1000
#define ICM20608_HIGH_SPI_BUS_SPEED  8*1000*1000
#define ICM20689_HIGH_SPI_BUS_SPEED  8*1000*1000
#define ICM20602_HIGH_SPI_BUS_SPEED 10*1000*1000
#define UNKNOWN_HIGH_SPI_BUS_SPEED   8*1000*1000 // Use the minimum


device::Device *MPU6000_SPI_interface(int bus, int device_type, bool external_bus);


class MPU6000_SPI : public device::SPI
{
public:
    MPU6000_SPI(int bus, uint32_t device, int device_type);
    ~MPU6000_SPI() override = default;

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

protected:
    int probe() override;

private:

    int _device_type;
    /* Helper to set the desired speed and isolate the register on return */

    int _max_frequency;
    void set_bus_frequency(unsigned &reg_speed_reg_out);
};

device::Device *
MPU6000_SPI_interface(int bus, int device_type, bool external_bus)
{
    int cs = SPIDEV_NONE(0);
    device::Device *interface = nullptr;

    if (external_bus) {

#if defined(PX4_SPI_BUS_EXT) || defined(PX4_SPI_BUS_EXTERNAL)

        switch (device_type) {

        case MPU_DEVICE_TYPE_MPU6000:
#  if defined(PX4_SPIDEV_EXT_MPU)
            cs  = PX4_SPIDEV_EXT_MPU;
# endif
            break;

        case MPU_DEVICE_TYPE_ICM20602:
#  if defined(PX4_SPIDEV_ICM_20602_EXT)
            cs = PX4_SPIDEV_ICM_20602_EXT;
#  endif
            break;

        case MPU_DEVICE_TYPE_ICM20608:
#  if defined(PX4_SPIDEV_EXT_ICM)
            cs = PX4_SPIDEV_EXT_ICM;
#  elif defined(PX4_SPIDEV_ICM_20608_EXT)
            cs = PX4_SPIDEV_ICM_20608_EXT;
#  endif
            break;

        case MPU_DEVICE_TYPE_ICM20689:
#  if defined(PX4_SPIDEV_ICM_20689_EXT)
            cs = PX4_SPIDEV_ICM_20689_EXT;
#  endif
            break;

        default:
            break;
        }

#endif

    } else {

        switch (device_type) {

        case MPU_DEVICE_TYPE_MPU6000:
#if defined(PX4_SPIDEV_MPU)
            cs = PX4_SPIDEV_MPU;
#endif
            break;

        case MPU_DEVICE_TYPE_ICM20602:
#if defined(PX4_SPIDEV_ICM_20602)
            cs = PX4_SPIDEV_ICM_20602;
#endif
            break;

        case MPU_DEVICE_TYPE_ICM20608:
#if defined(PX4_SPIDEV_ICM_20608)
            cs = PX4_SPIDEV_ICM_20608;
#endif
            break;

        case MPU_DEVICE_TYPE_ICM20689:
#  if defined(PX4_SPIDEV_ICM_20689)
            cs = PX4_SPIDEV_ICM_20689;
#  endif

        default:
            break;
        }
    }

    if (cs != SPIDEV_NONE(0)) {
        interface = new MPU6000_SPI(bus,  cs, device_type);
    }

    return interface;
}

MPU6000_SPI::MPU6000_SPI(int bus, uint32_t device, int device_type) :
    SPI("MPU6000", nullptr, bus, device, SPIDEV_MODE3, MPU6000_LOW_SPI_BUS_SPEED),
    _device_type(device_type)
{
}

void
MPU6000_SPI::set_bus_frequency(unsigned &reg_speed)
{
    /* Set the desired speed */
    set_frequency(MPU6000_IS_HIGH_SPEED(reg_speed) ? _max_frequency : MPU6000_LOW_SPI_BUS_SPEED);

    /* Isolate the register on return */
    reg_speed = MPU6000_REG(reg_speed);
}

int
MPU6000_SPI::write(unsigned reg_speed, void *data, unsigned count)
{
    uint8_t cmd[MPU_MAX_WRITE_BUFFER_SIZE];

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

    /* Set the desired speed and isolate the register */
    set_bus_frequency(reg_speed);

    cmd[0] = reg_speed | DIR_WRITE;
    cmd[1] = *(uint8_t *)data;

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

int
MPU6000_SPI::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
     * and we need to provied the buffer large enough for the callers data
     * and our command.
     */
    uint8_t cmd[3] = {0, 0, 0};

    uint8_t *pbuff  =  count < sizeof(MPUReport) ? cmd : (uint8_t *) data ;

    if (count < sizeof(MPUReport))  {
        /* add command */
        count++;
    }

    set_bus_frequency(reg_speed);

    /* Set command */
    pbuff[0] = reg_speed | DIR_READ ;

    /* Transfer the command and get the data */
    int ret = transfer(pbuff, pbuff, count);

    if (ret == OK && pbuff == &cmd[0]) {

        /* Adjust the count back */
        count--;

        /* Return the data */
        memcpy(data, &cmd[1], count);

    }

    return ret == OK ? count : ret;
}

int
MPU6000_SPI::probe()
{
    uint8_t whoami = 0;
    uint8_t expected = MPU_WHOAMI_6000;
    _max_frequency = UNKNOWN_HIGH_SPI_BUS_SPEED;

    switch (_device_type) {

    default:
    case MPU_DEVICE_TYPE_MPU6000:
        _max_frequency = MPU6000_HIGH_SPI_BUS_SPEED;
        break;

    case MPU_DEVICE_TYPE_ICM20602:
        expected = ICM_WHOAMI_20602;
        _max_frequency = ICM20602_HIGH_SPI_BUS_SPEED;
        break;

    case MPU_DEVICE_TYPE_ICM20608:
        expected = ICM_WHOAMI_20608;
        _max_frequency = ICM20608_HIGH_SPI_BUS_SPEED;
        break;

    case MPU_DEVICE_TYPE_ICM20689:
        expected = ICM_WHOAMI_20689;
        _max_frequency = ICM20689_HIGH_SPI_BUS_SPEED;
        break;
    }

    return (read(MPUREG_WHOAMI, &whoami, 1) > 0 && (whoami == expected)) ? 0 : -EIO;
}

#endif // PX4_SPIDEV_MPU