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