spidev_lib.c

/*
 *
 * This file is based on  of pyA20.
 * spi_lib.c python SPI extension.
 *
 * Copyright (c) 2014 Stefan Mavrodiev @ OLIMEX LTD, <support@olimex.com>
 *
 * pyA20 is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301, USA.
 * Adpated by Philippe Van Hecke <lemouchon@gmail.com>
 */


#include <stdio.h>
#include <stdint.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/ioctl.h>
//#include <libexplain/ioctl.h>
#include <string.h>

#include <linux/spi/spidev.h>

#include "spidev_lib.h"

int spi_open(char *device, spi_config_t config) {
    int fd;

    /* Open block device */
    fd = open(device, O_RDWR);
    if (fd < 0) {
        return fd;
    }

    /* Set SPI_POL and SPI_PHA */
    if (ioctl(fd, SPI_IOC_WR_MODE, &config.mode) < 0) {
        return -1;
    }
    if (ioctl(fd, SPI_IOC_RD_MODE, &config.mode) < 0) {
        return -1;
    }

    /* Set bits per word*/
    if (ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &config.bits_per_word) < 0) {
        return -1;
    }
    if (ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &config.bits_per_word) < 0) {
        return -1;
    }

    /* Set SPI speed*/
    if (ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &config.speed) < 0) {
        return -1;
    }
    if (ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &config.speed) < 0) {
        return -1;
    }

    /* Return file descriptor */
    return fd;
}

int spi_close(int fd) {
    return close(fd);
}

int spi_xfer(int fd, uint8_t *tx_buffer, uint8_t tx_len, uint8_t *rx_buffer, uint8_t rx_len)
{
    int l_nIntResult;
    struct spi_ioc_transfer spi_message[1];
    memset(spi_message, 0, sizeof(spi_message));

    spi_message[0].rx_buf = (unsigned long)rx_buffer;
    spi_message[0].tx_buf = (unsigned long)tx_buffer;
    spi_message[0].len = tx_len;

    l_nIntResult =  ioctl(fd, SPI_IOC_MESSAGE(1), spi_message);
    if ( l_nIntResult  < 0 )
    {
        //printf("%s: ioctl err: %d [ %s ]", __FUNCTION__, l_nIntResult,  explain_ioctl(fd, SPI_IOC_MESSAGE(1), spi_message));
        printf("%s: ioctl err: %d [ %s ]\r\n", __FUNCTION__, l_nIntResult,  strerror(errno));

    }
    return l_nIntResult;
}

int spi_read(int fd, uint8_t *rx_buffer, uint8_t rx_len){
    struct spi_ioc_transfer spi_message[1];
    memset(spi_message, 0, sizeof(spi_message));

    spi_message[0].rx_buf = (unsigned long)rx_buffer;
    spi_message[0].len = rx_len;


    return ioctl(fd, SPI_IOC_MESSAGE(1), spi_message);
}

int spi_write(int fd, uint8_t *tx_buffer, uint8_t tx_len){
    struct spi_ioc_transfer spi_message[1];
    memset(spi_message, 0, sizeof(spi_message));

    spi_message[0].tx_buf = (unsigned long)tx_buffer;
    spi_message[0].len = tx_len;

    return ioctl(fd, SPI_IOC_MESSAGE(1), spi_message);
}