Hy,
I wrote a simple user program to test an i2c bus driver. I found in
Documentation/i2c/dev-interface their is macro function to read data
(i2c_smbus_read_byte_data). I used it but I have link error when I compile :
$ arm-linux-gcc -O i2cread.c -o i2cread
/tmp/ccfa90st.o: In function `read_byte':
i2cread.c:(.text+0x3c): undefined reference to `i2c_smbus_read_byte_data'
collect2: ld returned 1 exit status
Is someone know what is the problem ?
Thanks in advance
FabM
/* a simple program to read on i2c bus
* Fabien Marteau <[EMAIL PROTECTED]>
*
* inspired from :
* ch7024: manage the Svideo controller CH7024
* author: [EMAIL PROTECTED]
*
*
** THE ARMADEUS PROJECT
**
** Copyright (C) year The source forge armadeus project team
**
** 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, 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
**
*/
#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
int fd;
/* Read a byte on the I2C bus
This is done by writing the register address
we want to access and then by reading this register
@param fd: file descriptor of the device
@param reg: register to access
@param buf: buffer used to store the result
@return : -1 in case of error otherwise 0
*/
__s32 read_byte( int fd,unsigned char addr, unsigned char reg)
{
int err;
__s32 res;
/* select address */
if(err=ioctl(fd,I2C_SLAVE,addr) < 0){
perror("can't select this address\n");
return err;
}
res = i2c_smbus_read_byte_data(fd,(__u8)reg);
if(res<0)
perror("read byte data error\n");
return res;
}
/* i2cread i2c-devfile addr*/
int main(int argc, char **argv){
unsigned char buf;
unsigned char addr;
unsigned char subaddr;
unsigned char value;
if(argc != 4){
printf("wrong args numbers\nsyntaxe (hexa) :\n");
printf("i2cread i2c-devfile addr subaddr\n");
return -1;
}
fd = open(argv[1],O_RDWR);
if(fd < 0){
printf("%d : can't open %s\n",fd,argv[1]);
return -1;
}
/* select address */
addr = (unsigned char )strtol(argv[2], (char **)NULL, 16);
/* select subaddress */
subaddr = (unsigned char )strtol(argv[3], (char **)NULL, 16);
buf = (unsigned char)read_byte(fd,addr, subaddr);
printf("Read component %02x at subaddress %02x->%02x\n",addr,subaddr,buf);
return value;
}
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