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/*
i2cget.c - A user-space program to read an I2C register.
Copyright (C) 2005-2008 Jean Delvare <khali@linux-fr.org>
Based on i2cset.c:
Copyright (C) 2001-2003 Frodo Looijaard <frodol@dds.nl>, and
Mark D. Studebaker <mdsxyz123@yahoo.com>
Copyright (C) 2004-2005 Jean Delvare <khali@linux-fr.org>
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., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301 USA.
*/
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/i2c-dev.h>
#include "i2cbusses.h"
#include "util.h"
#include "../version.h"
static void help(void) __attribute__ ((noreturn));
static void help(void)
{
fprintf(stderr,
"Usage: i2cget [-f] [-y] I2CBUS CHIP-ADDRESS [DATA-ADDRESS [MODE]]\n"
" I2CBUS is an integer or an I2C bus name\n"
" ADDRESS is an integer (0x03 - 0x77)\n"
" MODE is one of:\n"
" b (read byte data, default)\n"
" w (read word data)\n"
" c (write byte/read byte)\n"
" Append p for SMBus PEC\n");
exit(1);
}
static int check_funcs(int file, int size, int daddress, int pec)
{
unsigned long funcs;
/* check adapter functionality */
if (ioctl(file, I2C_FUNCS, &funcs) < 0) {
fprintf(stderr, "Error: Could not get the adapter "
"functionality matrix: %s\n", strerror(errno));
return -1;
}
switch (size) {
case I2C_SMBUS_BYTE:
if (!(funcs & I2C_FUNC_SMBUS_READ_BYTE)) {
fprintf(stderr, MISSING_FUNC_FMT, "SMBus receive byte");
return -1;
}
if (daddress >= 0
&& !(funcs & I2C_FUNC_SMBUS_WRITE_BYTE)) {
fprintf(stderr, MISSING_FUNC_FMT, "SMBus send byte");
return -1;
}
break;
case I2C_SMBUS_BYTE_DATA:
if (!(funcs & I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
fprintf(stderr, MISSING_FUNC_FMT, "SMBus read byte");
return -1;
}
break;
case I2C_SMBUS_WORD_DATA:
if (!(funcs & I2C_FUNC_SMBUS_READ_WORD_DATA)) {
fprintf(stderr, MISSING_FUNC_FMT, "SMBus read word");
return -1;
}
break;
}
if (pec
&& !(funcs & (I2C_FUNC_SMBUS_PEC | I2C_FUNC_I2C))) {
fprintf(stderr, "Warning: Adapter does "
"not seem to support PEC\n");
}
return 0;
}
static int confirm(const char *filename, int address, int size, int daddress,
int pec)
{
int dont = 0;
fprintf(stderr, "WARNING! This program can confuse your I2C "
"bus, cause data loss and worse!\n");
/* Don't let the user break his/her EEPROMs */
if (address >= 0x50 && address <= 0x57 && pec) {
fprintf(stderr, "STOP! EEPROMs are I2C devices, not "
"SMBus devices. Using PEC\non I2C devices may "
"result in unexpected results, such as\n"
"trashing the contents of EEPROMs. We can't "
"let you do that, sorry.\n");
return 0;
}
if (size == I2C_SMBUS_BYTE && daddress >= 0 && pec) {
fprintf(stderr, "WARNING! All I2C chips and some SMBus chips "
"will interpret a write\nbyte command with PEC as a"
"write byte data command, effectively writing a\n"
"value into a register!\n");
dont++;
}
fprintf(stderr, "I will read from device file %s, chip "
"address 0x%02x, ", filename, address);
if (daddress < 0)
fprintf(stderr, "current data\naddress");
else
fprintf(stderr, "data address\n0x%02x", daddress);
fprintf(stderr, ", using %s.\n",
size == I2C_SMBUS_BYTE ? (daddress < 0 ?
"read byte" : "write byte/read byte") :
size == I2C_SMBUS_BYTE_DATA ? "read byte data" :
"read word data");
if (pec)
fprintf(stderr, "PEC checking enabled.\n");
fprintf(stderr, "Continue? [%s] ", dont ? "y/N" : "Y/n");
fflush(stderr);
if (!user_ack(!dont)) {
fprintf(stderr, "Aborting on user request.\n");
return 0;
}
return 1;
}
int main(int argc, char *argv[])
{
char *end;
int res, i2cbus, address, size, file;
int daddress;
char filename[20];
int pec = 0;
int flags = 0;
int force = 0, yes = 0, version = 0;
/* handle (optional) flags first */
while (1+flags < argc && argv[1+flags][0] == '-') {
switch (argv[1+flags][1]) {
case 'V': version = 1; break;
case 'f': force = 1; break;
case 'y': yes = 1; break;
default:
fprintf(stderr, "Error: Unsupported option "
"\"%s\"!\n", argv[1+flags]);
help();
exit(1);
}
flags++;
}
if (version) {
fprintf(stderr, "i2cget version %s\n", VERSION);
exit(0);
}
if (argc < flags + 3)
help();
i2cbus = lookup_i2c_bus(argv[flags+1]);
if (i2cbus < 0)
help();
address = parse_i2c_address(argv[flags+2]);
if (address < 0)
help();
if (argc > flags + 3) {
size = I2C_SMBUS_BYTE_DATA;
daddress = strtol(argv[flags+3], &end, 0);
if (*end || daddress < 0 || daddress > 0xff) {
fprintf(stderr, "Error: Data address invalid!\n");
help();
}
} else {
size = I2C_SMBUS_BYTE;
daddress = -1;
}
if (argc > flags + 4) {
switch (argv[flags+4][0]) {
case 'b': size = I2C_SMBUS_BYTE_DATA; break;
case 'w': size = I2C_SMBUS_WORD_DATA; break;
case 'c': size = I2C_SMBUS_BYTE; break;
default:
fprintf(stderr, "Error: Invalid mode!\n");
help();
}
pec = argv[flags+4][1] == 'p';
}
file = open_i2c_dev(i2cbus, filename, 0);
if (file < 0
|| check_funcs(file, size, daddress, pec)
|| set_slave_addr(file, address, force))
exit(1);
if (!yes && !confirm(filename, address, size, daddress, pec))
exit(0);
if (pec && ioctl(file, I2C_PEC, 1) < 0) {
fprintf(stderr, "Error: Could not set PEC: %s\n",
strerror(errno));
close(file);
exit(1);
}
switch (size) {
case I2C_SMBUS_BYTE:
if (daddress >= 0) {
res = i2c_smbus_write_byte(file, daddress);
if (res < 0)
fprintf(stderr, "Warning - write failed\n");
}
res = i2c_smbus_read_byte(file);
break;
case I2C_SMBUS_WORD_DATA:
res = i2c_smbus_read_word_data(file, daddress);
break;
default: /* I2C_SMBUS_BYTE_DATA */
res = i2c_smbus_read_byte_data(file, daddress);
}
close(file);
if (res < 0) {
fprintf(stderr, "Error: Read failed\n");
exit(2);
}
printf("0x%0*x\n", size == I2C_SMBUS_WORD_DATA ? 4 : 2, res);
exit(0);
}
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