2 i2c-stub.c - I2C/SMBus chip emulator
4 Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>
5 Copyright (C) 2007 Jean Delvare <khali@linux-fr.org>
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 #include <linux/init.h>
25 #include <linux/module.h>
26 #include <linux/kernel.h>
27 #include <linux/slab.h>
28 #include <linux/errno.h>
29 #include <linux/i2c.h>
32 #define STUB_FUNC (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | \
33 I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | \
34 I2C_FUNC_SMBUS_I2C_BLOCK)
36 static unsigned short chip_addr[MAX_CHIPS];
37 module_param_array(chip_addr, ushort, NULL, S_IRUGO);
38 MODULE_PARM_DESC(chip_addr,
39 "Chip addresses (up to 10, between 0x03 and 0x77)");
41 static unsigned long functionality = STUB_FUNC;
42 module_param(functionality, ulong, S_IRUGO | S_IWUSR);
43 MODULE_PARM_DESC(functionality, "Override functionality bitfield");
47 u16 words[256]; /* Byte operations use the LSB as per SMBus
51 static struct stub_chip *stub_chips;
53 /* Return negative errno on error. */
54 static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
55 char read_write, u8 command, int size, union i2c_smbus_data * data)
59 struct stub_chip *chip = NULL;
61 /* Search for the right chip */
62 for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
63 if (addr == chip_addr[i]) {
64 chip = stub_chips + i;
74 dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr);
79 if (read_write == I2C_SMBUS_WRITE) {
80 chip->pointer = command;
81 dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
85 data->byte = chip->words[chip->pointer++] & 0xff;
86 dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
94 case I2C_SMBUS_BYTE_DATA:
95 if (read_write == I2C_SMBUS_WRITE) {
96 chip->words[command] &= 0xff00;
97 chip->words[command] |= data->byte;
98 dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
99 "wrote 0x%02x at 0x%02x.\n",
100 addr, data->byte, command);
102 data->byte = chip->words[command] & 0xff;
103 dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
104 "read 0x%02x at 0x%02x.\n",
105 addr, data->byte, command);
107 chip->pointer = command + 1;
112 case I2C_SMBUS_WORD_DATA:
113 if (read_write == I2C_SMBUS_WRITE) {
114 chip->words[command] = data->word;
115 dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
116 "wrote 0x%04x at 0x%02x.\n",
117 addr, data->word, command);
119 data->word = chip->words[command];
120 dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
121 "read 0x%04x at 0x%02x.\n",
122 addr, data->word, command);
128 case I2C_SMBUS_I2C_BLOCK_DATA:
129 len = data->block[0];
130 if (read_write == I2C_SMBUS_WRITE) {
131 for (i = 0; i < len; i++) {
132 chip->words[command + i] &= 0xff00;
133 chip->words[command + i] |= data->block[1 + i];
135 dev_dbg(&adap->dev, "i2c block data - addr 0x%02x, "
136 "wrote %d bytes at 0x%02x.\n",
139 for (i = 0; i < len; i++) {
141 chip->words[command + i] & 0xff;
143 dev_dbg(&adap->dev, "i2c block data - addr 0x%02x, "
144 "read %d bytes at 0x%02x.\n",
152 dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
155 } /* switch (size) */
160 static u32 stub_func(struct i2c_adapter *adapter)
162 return STUB_FUNC & functionality;
165 static const struct i2c_algorithm smbus_algorithm = {
166 .functionality = stub_func,
167 .smbus_xfer = stub_xfer,
170 static struct i2c_adapter stub_adapter = {
171 .owner = THIS_MODULE,
172 .class = I2C_CLASS_HWMON | I2C_CLASS_SPD,
173 .algo = &smbus_algorithm,
174 .name = "SMBus stub driver",
177 static int __init i2c_stub_init(void)
182 printk(KERN_ERR "i2c-stub: Please specify a chip address\n");
186 for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
187 if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) {
188 printk(KERN_ERR "i2c-stub: Invalid chip address "
189 "0x%02x\n", chip_addr[i]);
193 printk(KERN_INFO "i2c-stub: Virtual chip at 0x%02x\n",
197 /* Allocate memory for all chips at once */
198 stub_chips = kzalloc(i * sizeof(struct stub_chip), GFP_KERNEL);
200 printk(KERN_ERR "i2c-stub: Out of memory\n");
204 ret = i2c_add_adapter(&stub_adapter);
210 static void __exit i2c_stub_exit(void)
212 i2c_del_adapter(&stub_adapter);
216 MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
217 MODULE_DESCRIPTION("I2C stub driver");
218 MODULE_LICENSE("GPL");
220 module_init(i2c_stub_init);
221 module_exit(i2c_stub_exit);