/* This program is an example of writing and reading an EEPROM device via
SMBus on a GE Fanuc Embedded Systems, Inc. VMIVME-7809 Single Board
Computer.
To compile this program:
gcc -O vmieep.c -o vmieep
Before running this program, log in as root, then load the following
modules using:
/sbin/modprobe i2c-core
/sbin/modprobe i2c-dev
/sbin/modprobe i2c-i801
Loading the i2c-i801 module will create /dev/i2c-0, with
permissions = CRW- --- ---. Either run the vmieep program as root,
or change the permissions to CRW- RW- RW- as shown:
chmod 666 /dev/i2c-0
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#include <sys/time.h>
/* The inline smbus function definitions may or may not be in i2c-dev.h,
depending on the Linux distribution. Comment or uncomment the following
#include as necessary. */
#if 1
# include "vmieep.h"
#endif
#define EEPROM_SIZE 256 /* Adjust for actual number of bytes in EEPROM */
#define EEPROM_SMBUS_ADDR 0xAC /* Do NOT change! */
int gef_eeprom_read(int fd, unsigned char start_offset, unsigned char *buffer,
unsigned short buflen);
int gef_eeprom_write(int fd, unsigned char start_offset, unsigned char *buffer,
unsigned short buflen);
void gef_msec_delay(unsigned int msecs);
int main(int argc, char **argv)
{
int fd; /* File descriptor initialized with open() */
int status; /* Return code from ioctl() */
int adapter_num = 0; /* To match with /dev/i2c-0 */
char filename[20]; /* Name of special device file */
int i2c_addr = EEPROM_SMBUS_ADDR; /* SMBus address of EEPROM */
unsigned short offset; /* Which byte to access in the EEPROM */
unsigned short dataSize = 16; /* No more than EEPROM_SIZE */
unsigned char rbuffer[16]; /* Data read from EEPROM */
unsigned char wbuffer[16] =
{
/* Data written to EEPROM */
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F
};
/* Open the special device file for the SMBus */
sprintf(filename, "/dev/i2c-%d", adapter_num);
fd = open(filename, O_RDWR);
if (fd < 0)
{
printf("ERROR: open(%s) failed\n", filename);
printf("errno = %d, %s\n", errno, strerror(errno));
return -1;
}
printf("SUCCESS: open(%s) passed\n", filename);
/* Specify the EEPROM as the device we want to access.
*** IMPORTANT ***
The address is actually in the 7 LSBs, so shift
i2c_addr one bit to the right.*/
status = ioctl(fd, I2C_SLAVE, i2c_addr>>1);
if (status < 0)
{
printf("ERROR: ioctl(fd, I2C_SLAVE, 0x%02X) failed\n", i2c_addr);
printf("errno = %d, %s\n", errno, strerror(errno));
close(fd);
return -1;
}
printf("SUCCESS: ioctl(fd, I2C_SLAVE, 0x%02X>>1) passed\n", i2c_addr);
/* Read data from the EEPROM */
offset = 0;
if (gef_eeprom_read(fd, offset, rbuffer, dataSize) < 0)
{
printf("ERROR: gef_eeprom_read() failed\n");
close(fd);
return -1;
}
/* Dump the data read from the EEPROM */
for (offset=0; offset<dataSize; offset++)
{
printf("Offset: %02d Data: 0x%02X\n", offset, rbuffer[offset]);
}
/* Write data to the EEPROM */
printf("\nPress ENTER to write to the EEPROM");
getchar();
offset = 0;
if (gef_eeprom_write(fd, offset, wbuffer, dataSize) < 0)
{
printf("ERROR: gef_eeprom_write() failed\n");
close(fd);
return -1;
}
printf("SUCCESS: Data written to the EEPROM\n");
/* Read data again from the EEPROM */
printf("\nPress ENTER to read again from the EEPROM");
getchar();
offset = 0;
if (gef_eeprom_read(fd, offset, rbuffer, dataSize) < 0)
{
printf("ERROR: gef_eeprom_read() failed\n");
close(fd);
return -1;
}
/* Dump the data read from the EEPROM */
for (offset=0; offset<dataSize; offset++)
{
printf("Offset: %02d Data: 0x%02X\n", offset, rbuffer[offset]);
}
printf("\n");
/* Close the special device file */
close(fd);
return 0;
}
//////////////////////////////////////////////////////////////////////////////
//
// Function name : gef_eeprom_read
//
// Description : Read buflen bytes from the EEPROM beginning at start_offset
//
// Return type : 0 for success, -1 for failure
//
// Argument : int fd : File descriptor returned by open()
// Argument : unsigned char start_offset : Read bytes starting at this
// offset in the EEPROM. The sum of buflen and
// start_offset must not exceed the maximum size in bytes
// of the EEPROM
// Argument : unsigned char *buffer : Where to store the bytes read
// from the EEPROM. The buffer must be large enough
// to store buflen bytes read from the EEPROM.
// Argument : unsigned short buflen : The size in bytes of buffer, or
// how many bytes to read from the EEPROM. The sum of
// buflen and start_offset must not exceed the maximum
// size in bytes of the EEPROM.
//
int gef_eeprom_read(int fd, unsigned char start_offset, unsigned char *buffer,
unsigned short buflen)
{
int offset, index;
int data;
for (index=0, offset=start_offset; index<buflen &&
offset<EEPROM_SIZE; index++, offset++)
{
data = i2c_smbus_read_byte_data(fd, offset);
if (data == -1)
{
printf("ERROR: i2c_smbus_read_byte_data(fd, 0x%02X) failed\n",
offset);
printf("errno = %d, %s\n", errno, strerror(errno));
return -1;
}
buffer[index] = (unsigned char) (data);
}
return 0;
}
//////////////////////////////////////////////////////////////////////////////
//
// Function name : gef_eeprom_write
//
// Description : Write buflen bytes to the EEPROM beginning at start_offset
//
// Return type : 0 for success, -1 for failure
//
// Argument : int fd : File descriptor returned by open()
// Argument : unsigned char start_offset : Write bytes starting at this
// offset in the EEPROM. The sum of buflen and
// start_offset must not exceed the maximum size in bytes
// of the EEPROM
// Argument : unsigned char *buffer : Where to get the bytes to write
// to the EEPROM.
// Argument : unsigned short buflen : The size in bytes of buffer.
// The sum of buflen and start_offset must not exceed the
// maximum size in bytes of the EEPROM.
//
int gef_eeprom_write(int fd, unsigned char start_offset, unsigned char *buffer,
unsigned short buflen)
{
int offset, index;
int status;
for (index=0, offset=start_offset; index<buflen &&
offset<EEPROM_SIZE; index++, offset++)
{
status = i2c_smbus_write_byte_data(fd, offset, buffer[index]);
if (status < 0)
{
printf("ERROR: i2c_smbus_write_byte_data(fd, 0x%02X, 0x%02X) failed\n",
offset, buffer[index]);
printf("errno = %d, %s\n", errno, strerror(errno));
return -1;
}
/* Delay while the byte write completes */
gef_msec_delay(10);
}
return 0;
}
//////////////////////////////////////////////////////////////////////////////
//
// Function name : gef_msec_delay
//
// Description : Delay for a number of milliseconds before returning
//
// Return type : void
//
// Argument : unsigned int msecs : The number of milliseconds to delay
//
void gef_msec_delay(unsigned int msecs)
{
struct timeval s_current, s_start;
struct timezone tz;
unsigned int current, start;
/* Get initial time */
gettimeofday(&s_start, &tz);
start = s_start.tv_sec*1000000 + s_start.tv_usec;
/* Loop until msecs time have elapsed */
do
{
gettimeofday(&s_current, &tz);
current = s_current.tv_sec*1000000 + s_current.tv_usec;
} while ((current-start) < (msecs*1000));
}
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