PX4-Autopilot/src/lib/drivers/device/posix/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