spi linux 代码实例

/*
 * SPI testing utility (using spidev driver)
 *
 * Copyright (c) 2007  MontaVista Software, Inc.
 * Copyright (c) 2007  Anton Vorontsov <[email protected]>
 *
 * This program 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.
 *
 * Cross-compile with cross-gcc -I/path/to/cross-kernel/include
 */

#include <stdint.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <linux/spi/spidev.h>

#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))

static void pabort(const char *s)
{
    perror(s);
    abort();
}

static const char *device = "/dev/spidev1.1";
static uint8_t mode;
static uint8_t bits = 8;
static uint32_t speed = 500000;
static uint16_t delay;
uint8_t tx[4096] = {0};
uint8_t rx[ARRAY_SIZE(tx)] = {0, };
static void transfer(int fd)
{
    int ret;

    struct spi_ioc_transfer tr = {
        .tx_buf = (unsigned long)tx,
        .rx_buf = (unsigned long)rx,
        .len = ARRAY_SIZE(tx),
        .delay_usecs = delay,
        .speed_hz = speed,
        .bits_per_word = bits,
    };

    ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
    if (ret < 1)
        pabort("can't send spi message");

    //for (ret = 0; ret < ARRAY_SIZE(tx); ret++) {
    //  if (!(ret % 6))
    //      puts("");
    //  printf("%.2X ", rx[ret]);
    //}
    puts("");
}

static void print_usage(const char *prog)
{
    printf("Usage: %s [-DsbdlHOLC3]\n", prog);
    puts("  -D --device   device to use (default /dev/spidev1.1)\n"
         "  -s --speed    max speed (Hz)\n"
         "  -d --delay    delay (usec)\n"
         "  -b --bpw      bits per word \n"
         "  -l --loop     loopback\n"
         "  -H --cpha     clock phase\n"
         "  -O --cpol     clock polarity\n"
         "  -L --lsb      least significant bit first\n"
         "  -C --cs-high  chip select active high\n"
         "  -3 --3wire    SI/SO signals shared\n");
    exit(1);
}

static void parse_opts(int argc, char *argv[])
{
    while (1) {
        static const struct option lopts[] = {
            { "device",  1, 0, 'D' },
            { "speed",   1, 0, 's' },
            { "delay",   1, 0, 'd' },
            { "bpw",     1, 0, 'b' },
            { "loop",    0, 0, 'l' },
            { "cpha",    0, 0, 'H' },
            { "cpol",    0, 0, 'O' },
            { "lsb",     0, 0, 'L' },
            { "cs-high", 0, 0, 'C' },
            { "3wire",   0, 0, '3' },
            { "no-cs",   0, 0, 'N' },
            { "ready",   0, 0, 'R' },
            { NULL, 0, 0, 0 },
        };
        int c;

        c = getopt_long(argc, argv, "D:s:d:b:lHOLC3NR", lopts, NULL);

        if (c == -1)
            break;

        switch (c) {
        case 'D':
            device = optarg;
            break;
        case 's':
            speed = atoi(optarg);
            break;
        case 'd':
            delay = atoi(optarg);
            break;
        case 'b':
            bits = atoi(optarg);
            break;
        case 'l':
            mode |= SPI_LOOP;
            break;
        case 'H':
            mode |= SPI_CPHA;
            break;
        case 'O':
            mode |= SPI_CPOL;
            break;
        case 'L':
            mode |= SPI_LSB_FIRST;
            break;
        case 'C':
            mode |= SPI_CS_HIGH;
            break;
        case '3':
            mode |= SPI_3WIRE;
            break;
        case 'N':
            mode |= SPI_NO_CS;
            break;
        case 'R':
            mode |= SPI_READY;
            break;
        default:
            print_usage(argv[0]);
            break;
        }
    }
}

int main(int argc, char *argv[])
{
    int err = 0;
    unsigned char cmd = 32;
    unsigned int mode = 0;
    int handle_spi1dev = 0;
    int ret = 0;

    printf("init_SPI1()++\n");

    printf("handle_spi1dev = %x \n", handle_spi1dev);
    handle_spi1dev = open("/dev/spidev1.0",O_RDWR);

    if(handle_spi1dev < 0)
    {   
        printf("/dev/spidev1.0 error \n");
    }   
    mode = SPI_CPHA;
    err = ioctl(handle_spi1dev, SPI_IOC_WR_BITS_PER_WORD,&cmd);//change spi to 32bits mode
    if (err == -1)
        printf("can't set spi mode\n");

    err = ioctl(handle_spi1dev, SPI_IOC_WR_MODE, &mode);
    if (err == -1)
        printf("can't set spi mode\n");
    printf("handle_spi1dev = %x \n", handle_spi1dev);
    printf("init_SPI1()--\n");


    transfer(handle_spi1dev);

    close(handle_spi1dev);

    return ret;
}

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转载自blog.csdn.net/ruipeng_liu/article/details/82143015
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