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/*
i2c-stub.c - I2C/SMBus chip emulator
Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>
Copyright (C) 2007 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#define DEBUG 1
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#define MAX_CHIPS 10
static unsigned short chip_addr[MAX_CHIPS];
module_param_array(chip_addr, ushort, NULL, S_IRUGO);
MODULE_PARM_DESC(chip_addr,
"Chip addresses (up to 10, between 0x03 and 0x77)");
struct stub_chip {
u8 pointer;
u16 words[256]; /* Byte operations use the LSB as per SMBus
specification */
};
static struct stub_chip *stub_chips;
/* Return negative errno on error. */
static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
char read_write, u8 command, int size, union i2c_smbus_data * data)
{
s32 ret;
int i;
struct stub_chip *chip = NULL;
/* Search for the right chip */
for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
if (addr == chip_addr[i]) {
chip = stub_chips + i;
break;
}
}
if (!chip)
return -ENODEV;
switch (size) {
case I2C_SMBUS_QUICK:
dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr);
ret = 0;
break;
case I2C_SMBUS_BYTE:
if (read_write == I2C_SMBUS_WRITE) {
chip->pointer = command;
dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
"wrote 0x%02x.\n",
addr, command);
} else {
data->byte = chip->words[chip->pointer++] & 0xff;
dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
"read 0x%02x.\n",
addr, data->byte);
}
ret = 0;
break;
case I2C_SMBUS_BYTE_DATA:
if (read_write == I2C_SMBUS_WRITE) {
chip->words[command] &= 0xff00;
chip->words[command] |= data->byte;
dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
"wrote 0x%02x at 0x%02x.\n",
addr, data->byte, command);
} else {
data->byte = chip->words[command] & 0xff;
dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
"read 0x%02x at 0x%02x.\n",
addr, data->byte, command);
}
chip->pointer = command + 1;
ret = 0;
break;
case I2C_SMBUS_WORD_DATA:
if (read_write == I2C_SMBUS_WRITE) {
chip->words[command] = data->word;
dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
"wrote 0x%04x at 0x%02x.\n",
addr, data->word, command);
} else {
data->word = chip->words[command];
dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
"read 0x%04x at 0x%02x.\n",
addr, data->word, command);
}
ret = 0;
break;
default:
dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
ret = -EOPNOTSUPP;
break;
} /* switch (size) */
return ret;
}
static u32 stub_func(struct i2c_adapter *adapter)
{
return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA;
}
static const struct i2c_algorithm smbus_algorithm = {
.functionality = stub_func,
.smbus_xfer = stub_xfer,
};
static struct i2c_adapter stub_adapter = {
.owner = THIS_MODULE,
.class = I2C_CLASS_HWMON | I2C_CLASS_SPD,
.algo = &smbus_algorithm,
.name = "SMBus stub driver",
};
static int __init i2c_stub_init(void)
{
int i, ret;
if (!chip_addr[0]) {
printk(KERN_ERR "i2c-stub: Please specify a chip address\n");
return -ENODEV;
}
for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) {
printk(KERN_ERR "i2c-stub: Invalid chip address "
"0x%02x\n", chip_addr[i]);
return -EINVAL;
}
printk(KERN_INFO "i2c-stub: Virtual chip at 0x%02x\n",
chip_addr[i]);
}
/* Allocate memory for all chips at once */
stub_chips = kzalloc(i * sizeof(struct stub_chip), GFP_KERNEL);
if (!stub_chips) {
printk(KERN_ERR "i2c-stub: Out of memory\n");
return -ENOMEM;
}
ret = i2c_add_adapter(&stub_adapter);
if (ret)
kfree(stub_chips);
return ret;
}
static void __exit i2c_stub_exit(void)
{
i2c_del_adapter(&stub_adapter);
kfree(stub_chips);
}
MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
MODULE_DESCRIPTION("I2C stub driver");
MODULE_LICENSE("GPL");
module_init(i2c_stub_init);
module_exit(i2c_stub_exit);
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