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 18 #define DEBUG 1 19 #define pr_fmt(fmt) "i2c-stub: " fmt 20 21 #include <linux/errno.h> 22 #include <linux/i2c.h> 23 #include <linux/init.h> 24 #include <linux/kernel.h> 25 #include <linux/list.h> 26 #include <linux/module.h> 27 #include <linux/slab.h> 28 29 #define MAX_CHIPS 10 30 31 /* 32 * Support for I2C_FUNC_SMBUS_BLOCK_DATA is disabled by default and must 33 * be enabled explicitly by setting the I2C_FUNC_SMBUS_BLOCK_DATA bits 34 * in the 'functionality' module parameter. 35 */ 36 #define STUB_FUNC_DEFAULT \ 37 (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | \ 38 I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | \ 39 I2C_FUNC_SMBUS_I2C_BLOCK) 40 41 #define STUB_FUNC_ALL \ 42 (STUB_FUNC_DEFAULT | I2C_FUNC_SMBUS_BLOCK_DATA) 43 44 static unsigned short chip_addr[MAX_CHIPS]; 45 module_param_array(chip_addr, ushort, NULL, S_IRUGO); 46 MODULE_PARM_DESC(chip_addr, 47 "Chip addresses (up to 10, between 0x03 and 0x77)"); 48 49 static unsigned long functionality = STUB_FUNC_DEFAULT; 50 module_param(functionality, ulong, S_IRUGO | S_IWUSR); 51 MODULE_PARM_DESC(functionality, "Override functionality bitfield"); 52 53 /* Some chips have banked register ranges */ 54 55 static u8 bank_reg[MAX_CHIPS]; 56 module_param_array(bank_reg, byte, NULL, S_IRUGO); 57 MODULE_PARM_DESC(bank_reg, "Bank register"); 58 59 static u8 bank_mask[MAX_CHIPS]; 60 module_param_array(bank_mask, byte, NULL, S_IRUGO); 61 MODULE_PARM_DESC(bank_mask, "Bank value mask"); 62 63 static u8 bank_start[MAX_CHIPS]; 64 module_param_array(bank_start, byte, NULL, S_IRUGO); 65 MODULE_PARM_DESC(bank_start, "First banked register"); 66 67 static u8 bank_end[MAX_CHIPS]; 68 module_param_array(bank_end, byte, NULL, S_IRUGO); 69 MODULE_PARM_DESC(bank_end, "Last banked register"); 70 71 struct smbus_block_data { 72 struct list_head node; 73 u8 command; 74 u8 len; 75 u8 block[I2C_SMBUS_BLOCK_MAX]; 76 }; 77 78 struct stub_chip { 79 u8 pointer; 80 u16 words[256]; /* Byte operations use the LSB as per SMBus 81 specification */ 82 struct list_head smbus_blocks; 83 84 /* For chips with banks, extra registers are allocated dynamically */ 85 u8 bank_reg; 86 u8 bank_shift; 87 u8 bank_mask; 88 u8 bank_sel; /* Currently selected bank */ 89 u8 bank_start; 90 u8 bank_end; 91 u16 bank_size; 92 u16 *bank_words; /* Room for bank_mask * bank_size registers */ 93 }; 94 95 static struct stub_chip *stub_chips; 96 static int stub_chips_nr; 97 98 static struct smbus_block_data *stub_find_block(struct device *dev, 99 struct stub_chip *chip, 100 u8 command, bool create) 101 { 102 struct smbus_block_data *b, *rb = NULL; 103 104 list_for_each_entry(b, &chip->smbus_blocks, node) { 105 if (b->command == command) { 106 rb = b; 107 break; 108 } 109 } 110 if (rb == NULL && create) { 111 rb = devm_kzalloc(dev, sizeof(*rb), GFP_KERNEL); 112 if (rb == NULL) 113 return rb; 114 rb->command = command; 115 list_add(&rb->node, &chip->smbus_blocks); 116 } 117 return rb; 118 } 119 120 static u16 *stub_get_wordp(struct stub_chip *chip, u8 offset) 121 { 122 if (chip->bank_sel && 123 offset >= chip->bank_start && offset <= chip->bank_end) 124 return chip->bank_words + 125 (chip->bank_sel - 1) * chip->bank_size + 126 offset - chip->bank_start; 127 else 128 return chip->words + offset; 129 } 130 131 /* Return negative errno on error. */ 132 static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags, 133 char read_write, u8 command, int size, union i2c_smbus_data *data) 134 { 135 s32 ret; 136 int i, len; 137 struct stub_chip *chip = NULL; 138 struct smbus_block_data *b; 139 u16 *wordp; 140 141 /* Search for the right chip */ 142 for (i = 0; i < stub_chips_nr; i++) { 143 if (addr == chip_addr[i]) { 144 chip = stub_chips + i; 145 break; 146 } 147 } 148 if (!chip) 149 return -ENODEV; 150 151 switch (size) { 152 153 case I2C_SMBUS_QUICK: 154 dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr); 155 ret = 0; 156 break; 157 158 case I2C_SMBUS_BYTE: 159 if (read_write == I2C_SMBUS_WRITE) { 160 chip->pointer = command; 161 dev_dbg(&adap->dev, 162 "smbus byte - addr 0x%02x, wrote 0x%02x.\n", 163 addr, command); 164 } else { 165 wordp = stub_get_wordp(chip, chip->pointer++); 166 data->byte = *wordp & 0xff; 167 dev_dbg(&adap->dev, 168 "smbus byte - addr 0x%02x, read 0x%02x.\n", 169 addr, data->byte); 170 } 171 172 ret = 0; 173 break; 174 175 case I2C_SMBUS_BYTE_DATA: 176 wordp = stub_get_wordp(chip, command); 177 if (read_write == I2C_SMBUS_WRITE) { 178 *wordp &= 0xff00; 179 *wordp |= data->byte; 180 dev_dbg(&adap->dev, 181 "smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n", 182 addr, data->byte, command); 183 184 /* Set the bank as needed */ 185 if (chip->bank_words && command == chip->bank_reg) { 186 chip->bank_sel = 187 (data->byte >> chip->bank_shift) 188 & chip->bank_mask; 189 dev_dbg(&adap->dev, 190 "switching to bank %u.\n", 191 chip->bank_sel); 192 } 193 } else { 194 data->byte = *wordp & 0xff; 195 dev_dbg(&adap->dev, 196 "smbus byte data - addr 0x%02x, read 0x%02x at 0x%02x.\n", 197 addr, data->byte, command); 198 } 199 chip->pointer = command + 1; 200 201 ret = 0; 202 break; 203 204 case I2C_SMBUS_WORD_DATA: 205 wordp = stub_get_wordp(chip, command); 206 if (read_write == I2C_SMBUS_WRITE) { 207 *wordp = data->word; 208 dev_dbg(&adap->dev, 209 "smbus word data - addr 0x%02x, wrote 0x%04x at 0x%02x.\n", 210 addr, data->word, command); 211 } else { 212 data->word = *wordp; 213 dev_dbg(&adap->dev, 214 "smbus word data - addr 0x%02x, read 0x%04x at 0x%02x.\n", 215 addr, data->word, command); 216 } 217 218 ret = 0; 219 break; 220 221 case I2C_SMBUS_I2C_BLOCK_DATA: 222 /* 223 * We ignore banks here, because banked chips don't use I2C 224 * block transfers 225 */ 226 if (data->block[0] > 256 - command) /* Avoid overrun */ 227 data->block[0] = 256 - command; 228 len = data->block[0]; 229 if (read_write == I2C_SMBUS_WRITE) { 230 for (i = 0; i < len; i++) { 231 chip->words[command + i] &= 0xff00; 232 chip->words[command + i] |= data->block[1 + i]; 233 } 234 dev_dbg(&adap->dev, 235 "i2c block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n", 236 addr, len, command); 237 } else { 238 for (i = 0; i < len; i++) { 239 data->block[1 + i] = 240 chip->words[command + i] & 0xff; 241 } 242 dev_dbg(&adap->dev, 243 "i2c block data - addr 0x%02x, read %d bytes at 0x%02x.\n", 244 addr, len, command); 245 } 246 247 ret = 0; 248 break; 249 250 case I2C_SMBUS_BLOCK_DATA: 251 /* 252 * We ignore banks here, because chips typically don't use both 253 * banks and SMBus block transfers 254 */ 255 b = stub_find_block(&adap->dev, chip, command, false); 256 if (read_write == I2C_SMBUS_WRITE) { 257 len = data->block[0]; 258 if (len == 0 || len > I2C_SMBUS_BLOCK_MAX) { 259 ret = -EINVAL; 260 break; 261 } 262 if (b == NULL) { 263 b = stub_find_block(&adap->dev, chip, command, 264 true); 265 if (b == NULL) { 266 ret = -ENOMEM; 267 break; 268 } 269 } 270 /* Largest write sets read block length */ 271 if (len > b->len) 272 b->len = len; 273 for (i = 0; i < len; i++) 274 b->block[i] = data->block[i + 1]; 275 /* update for byte and word commands */ 276 chip->words[command] = (b->block[0] << 8) | b->len; 277 dev_dbg(&adap->dev, 278 "smbus block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n", 279 addr, len, command); 280 } else { 281 if (b == NULL) { 282 dev_dbg(&adap->dev, 283 "SMBus block read command without prior block write not supported\n"); 284 ret = -EOPNOTSUPP; 285 break; 286 } 287 len = b->len; 288 data->block[0] = len; 289 for (i = 0; i < len; i++) 290 data->block[i + 1] = b->block[i]; 291 dev_dbg(&adap->dev, 292 "smbus block data - addr 0x%02x, read %d bytes at 0x%02x.\n", 293 addr, len, command); 294 } 295 296 ret = 0; 297 break; 298 299 default: 300 dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n"); 301 ret = -EOPNOTSUPP; 302 break; 303 } /* switch (size) */ 304 305 return ret; 306 } 307 308 static u32 stub_func(struct i2c_adapter *adapter) 309 { 310 return STUB_FUNC_ALL & functionality; 311 } 312 313 static const struct i2c_algorithm smbus_algorithm = { 314 .functionality = stub_func, 315 .smbus_xfer = stub_xfer, 316 }; 317 318 static struct i2c_adapter stub_adapter = { 319 .owner = THIS_MODULE, 320 .class = I2C_CLASS_HWMON | I2C_CLASS_SPD, 321 .algo = &smbus_algorithm, 322 .name = "SMBus stub driver", 323 }; 324 325 static int __init i2c_stub_allocate_banks(int i) 326 { 327 struct stub_chip *chip = stub_chips + i; 328 329 chip->bank_reg = bank_reg[i]; 330 chip->bank_start = bank_start[i]; 331 chip->bank_end = bank_end[i]; 332 chip->bank_size = bank_end[i] - bank_start[i] + 1; 333 334 /* We assume that all bits in the mask are contiguous */ 335 chip->bank_mask = bank_mask[i]; 336 while (!(chip->bank_mask & 1)) { 337 chip->bank_shift++; 338 chip->bank_mask >>= 1; 339 } 340 341 chip->bank_words = kcalloc(chip->bank_mask * chip->bank_size, 342 sizeof(u16), 343 GFP_KERNEL); 344 if (!chip->bank_words) 345 return -ENOMEM; 346 347 pr_debug("Allocated %u banks of %u words each (registers 0x%02x to 0x%02x)\n", 348 chip->bank_mask, chip->bank_size, chip->bank_start, 349 chip->bank_end); 350 351 return 0; 352 } 353 354 static void i2c_stub_free(void) 355 { 356 int i; 357 358 for (i = 0; i < stub_chips_nr; i++) 359 kfree(stub_chips[i].bank_words); 360 kfree(stub_chips); 361 } 362 363 static int __init i2c_stub_init(void) 364 { 365 int i, ret; 366 367 if (!chip_addr[0]) { 368 pr_err("Please specify a chip address\n"); 369 return -ENODEV; 370 } 371 372 for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) { 373 if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) { 374 pr_err("Invalid chip address 0x%02x\n", 375 chip_addr[i]); 376 return -EINVAL; 377 } 378 379 pr_info("Virtual chip at 0x%02x\n", chip_addr[i]); 380 } 381 382 /* Allocate memory for all chips at once */ 383 stub_chips_nr = i; 384 stub_chips = kcalloc(stub_chips_nr, sizeof(struct stub_chip), 385 GFP_KERNEL); 386 if (!stub_chips) 387 return -ENOMEM; 388 389 for (i = 0; i < stub_chips_nr; i++) { 390 INIT_LIST_HEAD(&stub_chips[i].smbus_blocks); 391 392 /* Allocate extra memory for banked register ranges */ 393 if (bank_mask[i]) { 394 ret = i2c_stub_allocate_banks(i); 395 if (ret) 396 goto fail_free; 397 } 398 } 399 400 ret = i2c_add_adapter(&stub_adapter); 401 if (ret) 402 goto fail_free; 403 404 return 0; 405 406 fail_free: 407 i2c_stub_free(); 408 return ret; 409 } 410 411 static void __exit i2c_stub_exit(void) 412 { 413 i2c_del_adapter(&stub_adapter); 414 i2c_stub_free(); 415 } 416 417 MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>"); 418 MODULE_DESCRIPTION("I2C stub driver"); 419 MODULE_LICENSE("GPL"); 420 421 module_init(i2c_stub_init); 422 module_exit(i2c_stub_exit); 423