SPI.cpp

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/**
 * @file SPI.cpp
 *
 * Base class for devices connected via SPI.
 *
 */

#include "SPI.hpp"

#ifdef __PX4_LINUX

#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <linux/spi/spidev.h>

#include <px4_platform_common/px4_config.h>

namespace device
{

SPI::SPI(const char *name, const char *devname, int bus, uint32_t device, enum spi_mode_e mode, uint32_t frequency) :
    CDev(name, devname),
    _device(device),
    _mode(mode),
    _frequency(frequency)
{
    DEVICE_DEBUG("SPI::SPI name = %s devname = %s", name, devname);

    // fill in _device_id fields for a SPI device
    _device_id.devid_s.bus_type = DeviceBusType_SPI;
    _device_id.devid_s.bus = bus;
    _device_id.devid_s.address = (uint8_t)device;
    // devtype needs to be filled in by the driver
    _device_id.devid_s.devtype = 0;
}

SPI::~SPI()
{
    if (_fd >= 0) {
        ::close(_fd);
        _fd = -1;
    }
}

int
SPI::init()
{
    // Open the actual SPI device
    char dev_path[16];
    snprintf(dev_path, sizeof(dev_path), "/dev/spidev%i.%i", get_device_bus(), PX4_SPI_DEV_ID(_device));
    DEVICE_DEBUG("%s", dev_path);
    _fd = ::open(dev_path, O_RDWR);

    if (_fd < 0) {
        PX4_ERR("could not open %s", dev_path);
        return PX4_ERROR;
    }

    /* call the probe function to check whether the device is present */
    int ret = probe();

    if (ret != OK) {
        DEVICE_DEBUG("probe failed");
        return ret;
    }

    /* do base class init, which will create the device node, etc. */
    ret = CDev::init();

    if (ret != OK) {
        DEVICE_DEBUG("cdev init failed");
        return ret;
    }

    /* tell the workd where we are */
    DEVICE_LOG("on SPI bus %d at %d (%u KHz)", get_device_bus(), PX4_SPI_DEV_ID(_device), _frequency / 1000);

    return PX4_OK;
}

int
SPI::transfer(uint8_t *send, uint8_t *recv, unsigned len)
{
    if ((send == nullptr) && (recv == nullptr)) {
        return -EINVAL;
    }

    // set write mode of SPI
    int result = ::ioctl(_fd, SPI_IOC_WR_MODE, &_mode);

    if (result == -1) {
        PX4_ERR("can’t set spi mode");
        return PX4_ERROR;
    }

    spi_ioc_transfer spi_transfer[1] {}; // datastructures for linux spi interface

    spi_transfer[0].tx_buf = (uint64_t)send;
    spi_transfer[0].rx_buf = (uint64_t)recv;
    spi_transfer[0].len = len;
    spi_transfer[0].speed_hz = _frequency;
    spi_transfer[0].bits_per_word = 8;
    //spi_transfer[0].delay_usecs = 10;
    spi_transfer[0].cs_change = true;

    result = ::ioctl(_fd, SPI_IOC_MESSAGE(1), &spi_transfer);

    if (result != (int)len) {
        PX4_ERR("write failed. Reported %d bytes written (%s)", result, strerror(errno));
        return -1;
    }

    return 0;
}

int
SPI::transferhword(uint16_t *send, uint16_t *recv, unsigned len)
{
    if ((send == nullptr) && (recv == nullptr)) {
        return -EINVAL;
    }

    // set write mode of SPI
    int result = ::ioctl(_fd, SPI_IOC_WR_MODE, &_mode);

    if (result == -1) {
        PX4_ERR("can’t set spi mode");
        return PX4_ERROR;
    }

    int bits = 16;
    result = ::ioctl(_fd, SPI_IOC_WR_BITS_PER_WORD, &bits);

    if (result == -1) {
        PX4_ERR("can’t set 16 bit spi mode");
        return PX4_ERROR;
    }

    spi_ioc_transfer spi_transfer[1] {}; // datastructures for linux spi interface

    spi_transfer[0].tx_buf = (uint64_t)send;
    spi_transfer[0].rx_buf = (uint64_t)recv;
    spi_transfer[0].len = len * 2;
    spi_transfer[0].speed_hz = _frequency;
    //spi_transfer[0].bits_per_word = 8;
    //spi_transfer[0].delay_usecs = 10;
    spi_transfer[0].cs_change = true;

    result = ::ioctl(_fd, SPI_IOC_MESSAGE(1), &spi_transfer);

    if (result != (int)(len * 2)) {
        PX4_ERR("write failed. Reported %d bytes written (%s)", result, strerror(errno));
        return -1;
    }

    return 0;
}

} // namespace device

#endif // __PX4_LINUX