1/* 2 i2c-stub.c - I2C/SMBus chip emulator 3 4 Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com> 5 Copyright (C) 2007 Jean Delvare <khali@linux-fr.org> 6 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. 11 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. 16 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. 20*/ 21 22#define DEBUG 1 23 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> 30 31#define MAX_CHIPS 10 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) 35 36static unsigned short chip_addr[MAX_CHIPS]; 37module_param_array(chip_addr, ushort, NULL, S_IRUGO); 38MODULE_PARM_DESC(chip_addr, 39 "Chip addresses (up to 10, between 0x03 and 0x77)"); 40 41static unsigned long functionality = STUB_FUNC; 42module_param(functionality, ulong, S_IRUGO | S_IWUSR); 43MODULE_PARM_DESC(functionality, "Override functionality bitfield"); 44 45struct stub_chip { 46 u8 pointer; 47 u16 words[256]; /* Byte operations use the LSB as per SMBus 48 specification */ 49}; 50 51static struct stub_chip *stub_chips; 52 53/* Return negative errno on error. */ 54static 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) 56{ 57 s32 ret; 58 int i, len; 59 struct stub_chip *chip = NULL; 60 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; 65 break; 66 } 67 } 68 if (!chip) 69 return -ENODEV; 70 71 switch (size) { 72 73 case I2C_SMBUS_QUICK: 74 dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr); 75 ret = 0; 76 break; 77 78 case I2C_SMBUS_BYTE: 79 if (read_write == I2C_SMBUS_WRITE) { 80 chip->pointer = command; 81 dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, " 82 "wrote 0x%02x.\n", 83 addr, command); 84 } else { 85 data->byte = chip->words[chip->pointer++] & 0xff; 86 dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, " 87 "read 0x%02x.\n", 88 addr, data->byte); 89 } 90 91 ret = 0; 92 break; 93 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); 101 } else { 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); 106 } 107 chip->pointer = command + 1; 108 109 ret = 0; 110 break; 111 112 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); 118 } else { 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); 123 } 124 125 ret = 0; 126 break; 127 128 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]; 134 } 135 dev_dbg(&adap->dev, "i2c block data - addr 0x%02x, " 136 "wrote %d bytes at 0x%02x.\n", 137 addr, len, command); 138 } else { 139 for (i = 0; i < len; i++) { 140 data->block[1 + i] = 141 chip->words[command + i] & 0xff; 142 } 143 dev_dbg(&adap->dev, "i2c block data - addr 0x%02x, " 144 "read %d bytes at 0x%02x.\n", 145 addr, len, command); 146 } 147 148 ret = 0; 149 break; 150 151 default: 152 dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n"); 153 ret = -EOPNOTSUPP; 154 break; 155 } /* switch (size) */ 156 157 return ret; 158} 159 160static u32 stub_func(struct i2c_adapter *adapter) 161{ 162 return STUB_FUNC & functionality; 163} 164 165static const struct i2c_algorithm smbus_algorithm = { 166 .functionality = stub_func, 167 .smbus_xfer = stub_xfer, 168}; 169 170static 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", 175}; 176 177static int __init i2c_stub_init(void) 178{ 179 int i, ret; 180 181 if (!chip_addr[0]) { 182 printk(KERN_ERR "i2c-stub: Please specify a chip address\n"); 183 return -ENODEV; 184 } 185 186 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]); 190 return -EINVAL; 191 } 192 193 printk(KERN_INFO "i2c-stub: Virtual chip at 0x%02x\n", 194 chip_addr[i]); 195 } 196 197 /* Allocate memory for all chips at once */ 198 stub_chips = kzalloc(i * sizeof(struct stub_chip), GFP_KERNEL); 199 if (!stub_chips) { 200 printk(KERN_ERR "i2c-stub: Out of memory\n"); 201 return -ENOMEM; 202 } 203 204 ret = i2c_add_adapter(&stub_adapter); 205 if (ret) 206 kfree(stub_chips); 207 return ret; 208} 209 210static void __exit i2c_stub_exit(void) 211{ 212 i2c_del_adapter(&stub_adapter); 213 kfree(stub_chips); 214} 215 216MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>"); 217MODULE_DESCRIPTION("I2C stub driver"); 218MODULE_LICENSE("GPL"); 219 220module_init(i2c_stub_init); 221module_exit(i2c_stub_exit); 222