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

#define SPI_DEV_PATH "/dev/spidev0.0"

/*SPI 接收 、发送 缓冲区*/
unsigned char tx_buffer[100] = "hello the world !";
unsigned char rx_buffer[100];


int fd;                  					// SPI 控制引脚的设备文件描述符
static unsigned  mode = SPI_MODE_2;         //用于保存 SPI 工作模式
static uint8_t bits = 8;        			// 接收、发送数据位数
static uint32_t speed = 10000000; 			// 发送速度
static uint16_t delay;          			//保存延时时间

void transfer(int fd, uint8_t const *tx, uint8_t const *rx, size_t len)
{
  	int ret;

  	struct spi_ioc_transfer tr = {
      	.tx_buf = (unsigned long)tx,
      	.rx_buf = (unsigned long)rx,
      	.len = len,
      	.delay_usecs = delay,
      	.speed_hz = speed,
      	.bits_per_word = bits,
      	.tx_nbits = 1,
      	.rx_nbits = 1
  	};

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

void spi_init(int fd)
{
  	int ret = 0;

	// spi mode 设置SPI 工作模式
  	ret = ioctl(fd, SPI_IOC_WR_MODE32, &mode);
  	if (ret == -1)
  	  	printf("can't set spi mode\n");

	//  bits per word  设置一个字节的位数
  	ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);
  	if (ret == -1)
    	printf("can't set bits per word\n");

	//  max speed hz  设置SPI 最高工作频率
  	ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);
  	if (ret == -1)
    	printf("can't set max speed hz\n");

	// 打印
   	printf("spi mode: 0x%x\n", mode);
    printf("bits per word: %d\n", bits);
    printf("max speed: %d Hz (%d KHz)\n", speed, speed / 1000);
}

int main(int argc, char *argv[])
{
	int fd;
	
	if(argc < 2){
    printf("Wrong use !!!!\n");
        printf("Usage: %s [dev]\n",argv[0]);
        return -1;
    }
	/*打开 SPI 设备*/
    fd = open(argv[1], O_RDWR); // open file and enable read and  write
    if (fd < 0){
        printf("Can't open %s \n",argv[1]); // open i2c dev file fail
        exit(1);
    }

	/*初始化SPI */
	spi_init(fd);

	/*执行发送*/
	transfer(fd, tx_buffer, rx_buffer, sizeof(tx_buffer));

	/*打印 tx_buffer 和 rx_buffer*/
	printf("tx_buffer: \n %s\n ", tx_buffer);
	printf("rx_buffer: \n %s\n ", rx_buffer);

	close(fd);

	return 0;
}