test_i2c.c

基于linux xcale平台linux系统下I2c驱动程序

/*
	created by hzh, to support AT24C02 read/write
 */
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <linux/fb.h>
#include <sys/mman.h>
#include <sys/ioctl.h>

#define I2C_SLAVE		0x0703	/* Change slave address			*/
#define	I2C_BUS_MODE	0x0780

#define	EEPROM_I2C_ADDR	0x50

void udelay(int usec)
{
	fd_set rfds;

	struct timeval tv;

	FD_ZERO(&rfds);
	FD_SET(0, &rfds);

	tv.tv_sec = 0;
	tv.tv_usec = usec;

	select(1, &rfds, NULL,  NULL, &tv);

}

void mdelay(int msec)
{
//	int i;
	
//	for(i=0; i<msec; i++)
//		udelay(1000);
	udelay(msec*1000);
}

static int i2c_write(int fd, __u8 reg, __u8 val)
{
	int retries;
	__u8 data[2];

	data[0] = reg;
	data[1] = val;
	for(retries=5; retries; retries--) {
		if(write(fd, data, 2)==2)
			return 0;
		mdelay(10);
	}
	return -1;
}

static int i2c_read(int fd, __u8 reg, __u8 *val)
{
	int retries;

	for(retries=5; retries; retries--)
		if(write(fd, &reg, 1)==1)
			if(read(fd, val, 1)==1)
				return 0;
	return -1;
}

int main(int argc, char *argv[])
{
	int i, count, fd;
	__u8 buf[256];

	fd = open("/dev/i2c/0", O_RDWR);
	if(fd<0) {
		fd = open("/dev/misc/i2c", O_RDWR);
		if(fd<0) {
			printf("fail to open i2c adapter device!\n");
			return -1;
		}
	}

	if(ioctl(fd, I2C_SLAVE, EEPROM_I2C_ADDR)<0) {
		printf("fail to set i2c device slave address!\n");
		close(fd);
		return -1;
	}
	printf("set slave address to 0x%x success!\n", EEPROM_I2C_ADDR);
	if(ioctl(fd, I2C_BUS_MODE, 1)<0)
		printf("set bus mode fail!\n");
	else
		printf("set bus mode ok!\n");

	for(i=0; i<sizeof(buf); i++)
		if(i2c_write(fd, i, i))
			break;
	printf("write %d bytes.\n", i);

	for(i=0; i<sizeof(buf); i++)
		buf[i] = 0;
	
	for(i=0; i<sizeof(buf); i++)
		if(i2c_read(fd, i, buf+i))
			break;
	printf("read %d bytes.\n", i);
	count = i;
	for(i=0; i<count; i++)
		printf("%02x %c", buf[i], ((i+1)%16)?',':'\n');

	close(fd);

	return 0;
}