本文主要是介绍spi 环回测试代码，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
spi环回测试代码，检测spi主模式通信链路是否正常。
/** SPI testing utility (using spidev driver)** Copyright (c) 2007 MontaVista Software, Inc.* Copyright (c) 2007 Anton Vorontsov <avorontsov@ru.mvista.com>** 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/spidev2.0";
static uint8_t mode;
static uint8_t bits = 8;
static uint32_t speed = 500000;
static uint16_t delay;static void transfer(int fd)
{int ret;uint8_t tx[] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,0x40, 0x00, 0x00, 0x00, 0x00, 0x95,0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,0xDE, 0xAD, 0xBE, 0xEF, 0xBA, 0xAD,0xF0, 0x0D,};uint8_t rx[ARRAY_SIZE(tx)] = {0, };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 ret = 0;int fd;parse_opts(argc, argv);fd = open(device, O_RDWR);if (fd < 0)pabort("can't open device");/** spi mode*/ret = ioctl(fd, SPI_IOC_WR_MODE, &mode);if (ret == -1)pabort("can't set spi mode");ret = ioctl(fd, SPI_IOC_RD_MODE, &mode);if (ret == -1)pabort("can't get spi mode");/** bits per word*/ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);if (ret == -1)pabort("can't set bits per word");ret = ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits);if (ret == -1)pabort("can't get bits per word");/** max speed hz*/ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);if (ret == -1)pabort("can't set max speed hz");ret = ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed);if (ret == -1)pabort("can't get max speed hz");printf("spi mode: %d\n", mode);printf("bits per word: %d\n", bits);printf("max speed: %d Hz (%d KHz)\n", speed, speed/1000);transfer(fd);close(fd);return ret;
}
短接SDO和SDI，测试结果：
root@OpenWrt:~# ./spidev_test -D /dev/spidev2.0 -H -O
spi mode: 3
bits per word: 8
max speed: 500000 Hz (500 KHz)FF FF FF FF FF FF
40 00 00 00 00 95
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
DE AD BE EF BA AD
F0 0D
供后面速查使用。
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