1 /* 2 i2c-stub.c - I2C/SMBus chip emulator 3 4 Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com> 5 Copyright (C) 2007-2014 Jean Delvare <jdelvare@suse.de> 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 #include <linux/list.h> 31 32 #define MAX_CHIPS 10 33 34 /* 35 * Support for I2C_FUNC_SMBUS_BLOCK_DATA is disabled by default and must 36 * be enabled explicitly by setting the I2C_FUNC_SMBUS_BLOCK_DATA bits 37 * in the 'functionality' module parameter. 38 */ 39 #define STUB_FUNC_DEFAULT \ 40 (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | \ 41 I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | \ 42 I2C_FUNC_SMBUS_I2C_BLOCK) 43 44 #define STUB_FUNC_ALL \ 45 (STUB_FUNC_DEFAULT | I2C_FUNC_SMBUS_BLOCK_DATA) 46 47 static unsigned short chip_addr[MAX_CHIPS]; 48 module_param_array(chip_addr, ushort, NULL, S_IRUGO); 49 MODULE_PARM_DESC(chip_addr, 50 "Chip addresses (up to 10, between 0x03 and 0x77)"); 51 52 static unsigned long functionality = STUB_FUNC_DEFAULT; 53 module_param(functionality, ulong, S_IRUGO | S_IWUSR); 54 MODULE_PARM_DESC(functionality, "Override functionality bitfield"); 55 56 /* Some chips have banked register ranges */ 57 58 static u8 bank_reg[MAX_CHIPS]; 59 module_param_array(bank_reg, byte, NULL, S_IRUGO); 60 MODULE_PARM_DESC(bank_reg, "Bank register"); 61 62 static u8 bank_mask[MAX_CHIPS]; 63 module_param_array(bank_mask, byte, NULL, S_IRUGO); 64 MODULE_PARM_DESC(bank_mask, "Bank value mask"); 65 66 static u8 bank_start[MAX_CHIPS]; 67 module_param_array(bank_start, byte, NULL, S_IRUGO); 68 MODULE_PARM_DESC(bank_start, "First banked register"); 69 70 static u8 bank_end[MAX_CHIPS]; 71 module_param_array(bank_end, byte, NULL, S_IRUGO); 72 MODULE_PARM_DESC(bank_end, "Last banked register"); 73 74 struct smbus_block_data { 75 struct list_head node; 76 u8 command; 77 u8 len; 78 u8 block[I2C_SMBUS_BLOCK_MAX]; 79 }; 80 81 struct stub_chip { 82 u8 pointer; 83 u16 words[256]; /* Byte operations use the LSB as per SMBus 84 specification */ 85 struct list_head smbus_blocks; 86 87 /* For chips with banks, extra registers are allocated dynamically */ 88 u8 bank_reg; 89 u8 bank_shift; 90 u8 bank_mask; 91 u8 bank_sel; /* Currently selected bank */ 92 u8 bank_start; 93 u8 bank_end; 94 u16 bank_size; 95 u16 *bank_words; /* Room for bank_mask * bank_size registers */ 96 }; 97 98 static struct stub_chip *stub_chips; 99 static int stub_chips_nr; 100 101 static struct smbus_block_data *stub_find_block(struct device *dev, 102 struct stub_chip *chip, 103 u8 command, bool create) 104 { 105 struct smbus_block_data *b, *rb = NULL; 106 107 list_for_each_entry(b, &chip->smbus_blocks, node) { 108 if (b->command == command) { 109 rb = b; 110 break; 111 } 112 } 113 if (rb == NULL && create) { 114 rb = devm_kzalloc(dev, sizeof(*rb), GFP_KERNEL); 115 if (rb == NULL) 116 return rb; 117 rb->command = command; 118 list_add(&rb->node, &chip->smbus_blocks); 119 } 120 return rb; 121 } 122 123 static u16 *stub_get_wordp(struct stub_chip *chip, u8 offset) 124 { 125 if (chip->bank_sel && 126 offset >= chip->bank_start && offset <= chip->bank_end) 127 return chip->bank_words + 128 (chip->bank_sel - 1) * chip->bank_size + 129 offset - chip->bank_start; 130 else 131 return chip->words + offset; 132 } 133 134 /* Return negative errno on error. */ 135 static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags, 136 char read_write, u8 command, int size, union i2c_smbus_data *data) 137 { 138 s32 ret; 139 int i, len; 140 struct stub_chip *chip = NULL; 141 struct smbus_block_data *b; 142 u16 *wordp; 143 144 /* Search for the right chip */ 145 for (i = 0; i < stub_chips_nr; i++) { 146 if (addr == chip_addr[i]) { 147 chip = stub_chips + i; 148 break; 149 } 150 } 151 if (!chip) 152 return -ENODEV; 153 154 switch (size) { 155 156 case I2C_SMBUS_QUICK: 157 dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr); 158 ret = 0; 159 break; 160 161 case I2C_SMBUS_BYTE: 162 if (read_write == I2C_SMBUS_WRITE) { 163 chip->pointer = command; 164 dev_dbg(&adap->dev, 165 "smbus byte - addr 0x%02x, wrote 0x%02x.\n", 166 addr, command); 167 } else { 168 wordp = stub_get_wordp(chip, chip->pointer++); 169 data->byte = *wordp & 0xff; 170 dev_dbg(&adap->dev, 171 "smbus byte - addr 0x%02x, read 0x%02x.\n", 172 addr, data->byte); 173 } 174 175 ret = 0; 176 break; 177 178 case I2C_SMBUS_BYTE_DATA: 179 wordp = stub_get_wordp(chip, command); 180 if (read_write == I2C_SMBUS_WRITE) { 181 *wordp &= 0xff00; 182 *wordp |= data->byte; 183 dev_dbg(&adap->dev, 184 "smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n", 185 addr, data->byte, command); 186 187 /* Set the bank as needed */ 188 if (chip->bank_words && command == chip->bank_reg) { 189 chip->bank_sel = 190 (data->byte >> chip->bank_shift) 191 & chip->bank_mask; 192 dev_dbg(&adap->dev, 193 "switching to bank %u.\n", 194 chip->bank_sel); 195 } 196 } else { 197 data->byte = *wordp & 0xff; 198 dev_dbg(&adap->dev, 199 "smbus byte data - addr 0x%02x, read 0x%02x at 0x%02x.\n", 200 addr, data->byte, command); 201 } 202 chip->pointer = command + 1; 203 204 ret = 0; 205 break; 206 207 case I2C_SMBUS_WORD_DATA: 208 wordp = stub_get_wordp(chip, command); 209 if (read_write == I2C_SMBUS_WRITE) { 210 *wordp = data->word; 211 dev_dbg(&adap->dev, 212 "smbus word data - addr 0x%02x, wrote 0x%04x at 0x%02x.\n", 213 addr, data->word, command); 214 } else { 215 data->word = *wordp; 216 dev_dbg(&adap->dev, 217 "smbus word data - addr 0x%02x, read 0x%04x at 0x%02x.\n", 218 addr, data->word, command); 219 } 220 221 ret = 0; 222 break; 223 224 case I2C_SMBUS_I2C_BLOCK_DATA: 225 /* 226 * We ignore banks here, because banked chips don't use I2C 227 * block transfers 228 */ 229 if (data->block[0] > 256 - command) /* Avoid overrun */ 230 data->block[0] = 256 - command; 231 len = data->block[0]; 232 if (read_write == I2C_SMBUS_WRITE) { 233 for (i = 0; i < len; i++) { 234 chip->words[command + i] &= 0xff00; 235 chip->words[command + i] |= data->block[1 + i]; 236 } 237 dev_dbg(&adap->dev, 238 "i2c block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n", 239 addr, len, command); 240 } else { 241 for (i = 0; i < len; i++) { 242 data->block[1 + i] = 243 chip->words[command + i] & 0xff; 244 } 245 dev_dbg(&adap->dev, 246 "i2c block data - addr 0x%02x, read %d bytes at 0x%02x.\n", 247 addr, len, command); 248 } 249 250 ret = 0; 251 break; 252 253 case I2C_SMBUS_BLOCK_DATA: 254 /* 255 * We ignore banks here, because chips typically don't use both 256 * banks and SMBus block transfers 257 */ 258 b = stub_find_block(&adap->dev, chip, command, false); 259 if (read_write == I2C_SMBUS_WRITE) { 260 len = data->block[0]; 261 if (len == 0 || len > I2C_SMBUS_BLOCK_MAX) { 262 ret = -EINVAL; 263 break; 264 } 265 if (b == NULL) { 266 b = stub_find_block(&adap->dev, chip, command, 267 true); 268 if (b == NULL) { 269 ret = -ENOMEM; 270 break; 271 } 272 } 273 /* Largest write sets read block length */ 274 if (len > b->len) 275 b->len = len; 276 for (i = 0; i < len; i++) 277 b->block[i] = data->block[i + 1]; 278 /* update for byte and word commands */ 279 chip->words[command] = (b->block[0] << 8) | b->len; 280 dev_dbg(&adap->dev, 281 "smbus block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n", 282 addr, len, command); 283 } else { 284 if (b == NULL) { 285 dev_dbg(&adap->dev, 286 "SMBus block read command without prior block write not supported\n"); 287 ret = -EOPNOTSUPP; 288 break; 289 } 290 len = b->len; 291 data->block[0] = len; 292 for (i = 0; i < len; i++) 293 data->block[i + 1] = b->block[i]; 294 dev_dbg(&adap->dev, 295 "smbus block data - addr 0x%02x, read %d bytes at 0x%02x.\n", 296 addr, len, command); 297 } 298 299 ret = 0; 300 break; 301 302 default: 303 dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n"); 304 ret = -EOPNOTSUPP; 305 break; 306 } /* switch (size) */ 307 308 return ret; 309 } 310 311 static u32 stub_func(struct i2c_adapter *adapter) 312 { 313 return STUB_FUNC_ALL & functionality; 314 } 315 316 static const struct i2c_algorithm smbus_algorithm = { 317 .functionality = stub_func, 318 .smbus_xfer = stub_xfer, 319 }; 320 321 static struct i2c_adapter stub_adapter = { 322 .owner = THIS_MODULE, 323 .class = I2C_CLASS_HWMON | I2C_CLASS_SPD, 324 .algo = &smbus_algorithm, 325 .name = "SMBus stub driver", 326 }; 327 328 static int __init i2c_stub_allocate_banks(int i) 329 { 330 struct stub_chip *chip = stub_chips + i; 331 332 chip->bank_reg = bank_reg[i]; 333 chip->bank_start = bank_start[i]; 334 chip->bank_end = bank_end[i]; 335 chip->bank_size = bank_end[i] - bank_start[i] + 1; 336 337 /* We assume that all bits in the mask are contiguous */ 338 chip->bank_mask = bank_mask[i]; 339 while (!(chip->bank_mask & 1)) { 340 chip->bank_shift++; 341 chip->bank_mask >>= 1; 342 } 343 344 chip->bank_words = kzalloc(chip->bank_mask * chip->bank_size * 345 sizeof(u16), GFP_KERNEL); 346 if (!chip->bank_words) 347 return -ENOMEM; 348 349 pr_debug("i2c-stub: Allocated %u banks of %u words each (registers 0x%02x to 0x%02x)\n", 350 chip->bank_mask, chip->bank_size, chip->bank_start, 351 chip->bank_end); 352 353 return 0; 354 } 355 356 static void i2c_stub_free(void) 357 { 358 int i; 359 360 for (i = 0; i < stub_chips_nr; i++) 361 kfree(stub_chips[i].bank_words); 362 kfree(stub_chips); 363 } 364 365 static int __init i2c_stub_init(void) 366 { 367 int i, ret; 368 369 if (!chip_addr[0]) { 370 pr_err("i2c-stub: Please specify a chip address\n"); 371 return -ENODEV; 372 } 373 374 for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) { 375 if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) { 376 pr_err("i2c-stub: Invalid chip address 0x%02x\n", 377 chip_addr[i]); 378 return -EINVAL; 379 } 380 381 pr_info("i2c-stub: Virtual chip at 0x%02x\n", chip_addr[i]); 382 } 383 384 /* Allocate memory for all chips at once */ 385 stub_chips_nr = i; 386 stub_chips = kcalloc(stub_chips_nr, sizeof(struct stub_chip), 387 GFP_KERNEL); 388 if (!stub_chips) { 389 pr_err("i2c-stub: Out of memory\n"); 390 return -ENOMEM; 391 } 392 for (i = 0; i < stub_chips_nr; i++) { 393 INIT_LIST_HEAD(&stub_chips[i].smbus_blocks); 394 395 /* Allocate extra memory for banked register ranges */ 396 if (bank_mask[i]) { 397 ret = i2c_stub_allocate_banks(i); 398 if (ret) 399 goto fail_free; 400 } 401 } 402 403 ret = i2c_add_adapter(&stub_adapter); 404 if (ret) 405 goto fail_free; 406 407 return 0; 408 409 fail_free: 410 i2c_stub_free(); 411 return ret; 412 } 413 414 static void __exit i2c_stub_exit(void) 415 { 416 i2c_del_adapter(&stub_adapter); 417 i2c_stub_free(); 418 } 419 420 MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>"); 421 MODULE_DESCRIPTION("I2C stub driver"); 422 MODULE_LICENSE("GPL"); 423 424 module_init(i2c_stub_init); 425 module_exit(i2c_stub_exit); 426