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/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#define _GNU_SOURCE /* for asprintf */
#include <errno.h>
#include <fcntl.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include "comm-host.h"
#define EC_I2C_ADDR 0x1e
#define I2C_ADAPTER_NODE "/sys/class/i2c-adapter/i2c-%d/%d-%04x/name"
#define I2C_ADAPTER_NAME "cros-ec-i2c"
#define I2C_MAX_ADAPTER 32
#define I2C_NODE "/dev/i2c-%d"
#ifdef DEBUG
#define debug(format, arg...) printf(format, ##arg)
#else
#define debug(...)
#endif
static int i2c_fd = -1;
/*
* Sends a command to the EC (protocol v2). Returns the command status code, or
* -1 if other error.
*
* Returns >= 0 for success, or negative if error.
*
*/
static int ec_command_i2c(int command, int version,
const void *outdata, int outsize,
void *indata, int insize)
{
struct i2c_rdwr_ioctl_data data;
int ret = -1;
int i;
int req_len;
uint8_t *req_buf = NULL;
int resp_len;
uint8_t *resp_buf = NULL;
const uint8_t *c;
uint8_t *d;
uint8_t sum;
struct i2c_msg i2c_msg[2];
if (version > 1) {
fprintf(stderr, "Command versions >1 unsupported.\n");
return -EC_RES_ERROR;
}
if (i2c_fd < 0) {
fprintf(stderr, "i2c_fd is negative: %d\n", i2c_fd);
return -EC_RES_ERROR;
}
if (ioctl(i2c_fd, I2C_SLAVE, EC_I2C_ADDR) < 0) {
fprintf(stderr, "Cannot set I2C slave address\n");
return -EC_RES_ERROR;
}
i2c_msg[0].addr = EC_I2C_ADDR;
i2c_msg[0].flags = 0;
i2c_msg[1].addr = EC_I2C_ADDR;
i2c_msg[1].flags = I2C_M_RD;
data.msgs = i2c_msg;
data.nmsgs = 2;
/*
* allocate larger packet
* (version, command, size, ..., checksum)
*/
req_len = outsize + EC_PROTO2_REQUEST_OVERHEAD;
req_buf = calloc(1, req_len);
if (!req_buf)
goto done;
i2c_msg[0].len = req_len;
i2c_msg[0].buf = (char *)req_buf;
req_buf[0] = version + EC_CMD_VERSION0;
req_buf[1] = command;
req_buf[2] = outsize;
debug("i2c req %02x:", command);
sum = req_buf[0] + req_buf[1] + req_buf[2];
/* copy message payload and compute checksum */
for (i = 0, c = outdata; i < outsize; i++, c++) {
req_buf[i + 3] = *c;
sum += *c;
debug(" %02x", *c);
}
debug(", sum=%02x\n", sum);
req_buf[req_len - 1] = sum;
/*
* allocate larger packet
* (result, size, ..., checksum)
*/
resp_len = insize + EC_PROTO2_RESPONSE_OVERHEAD;
resp_buf = calloc(1, resp_len);
if (!resp_buf)
goto done;
i2c_msg[1].len = resp_len;
i2c_msg[1].buf = (char *)resp_buf;
/* send command to EC and read answer */
ret = ioctl(i2c_fd, I2C_RDWR, &data);
if (ret < 0) {
fprintf(stderr, "i2c transfer failed: %d (err: %d)\n",
ret, errno);
ret = -EC_RES_ERROR;
goto done;
}
/* check response error code */
ret = resp_buf[0];
/* TODO(crosbug.com/p/23824): handle EC_RES_IN_PROGRESS case. */
resp_len = resp_buf[1];
if (resp_len > insize) {
fprintf(stderr, "response size is too large %d > %d\n",
resp_len, insize);
ret = -EC_RES_ERROR;
goto done;
}
if (ret) {
debug("command 0x%02x returned an error %d\n",
command, i2c_msg[1].buf[0]);
/* Translate ERROR to -ERROR and offset */
ret = -EECRESULT - ret;
} else if (insize) {
debug("i2c resp :");
/* copy response packet payload and compute checksum */
sum = resp_buf[0] + resp_buf[1];
for (i = 0, d = indata; i < resp_len; i++, d++) {
*d = resp_buf[i + 2];
sum += *d;
debug(" %02x", *d);
}
debug(", sum=%02x\n", sum);
if (sum != resp_buf[resp_len + 2]) {
fprintf(stderr, "bad packet checksum\n");
ret = -EC_RES_ERROR;
goto done;
}
/* Return output buffer size */
ret = resp_len;
}
done:
if (resp_buf)
free(resp_buf);
if (req_buf)
free(req_buf);
return ret;
}
int comm_init_i2c(void)
{
char *file_path;
char buffer[64];
FILE *f;
int i;
/* find the device number based on the adapter name */
for (i = 0; i < I2C_MAX_ADAPTER; i++) {
if (asprintf(&file_path, I2C_ADAPTER_NODE,
i, i, EC_I2C_ADDR) < 0)
return -1;
f = fopen(file_path, "r");
if (f) {
if (fgets(buffer, sizeof(buffer), f) &&
!strncmp(buffer, I2C_ADAPTER_NAME, 6)) {
free(file_path);
break;
}
fclose(f);
}
free(file_path);
}
if (i == I2C_MAX_ADAPTER) {
fprintf(stderr, "Cannot find I2C adapter\n");
return -1;
}
if (asprintf(&file_path, I2C_NODE, i) < 0)
return -1;
debug("using I2C adapter %s\n", file_path);
i2c_fd = open(file_path, O_RDWR);
if (i2c_fd < 0)
fprintf(stderr, "Cannot open %s : %d\n", file_path, errno);
free(file_path);
ec_command_proto = ec_command_i2c;
ec_max_outsize = ec_max_insize = EC_PROTO2_MAX_PARAM_SIZE;
return 0;
}
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