drivers/misc/eeprom/at24.c

   1 /*
   2  * at24.c - handle most I2C EEPROMs
   3  *
   4  * Copyright (C) 2005-2007 David Brownell
   5  * Copyright (C) 2008 Wolfram Sang, Pengutronix
   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 #include <linux/kernel.h>
  13 #include <linux/init.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/delay.h>
  17 #include <linux/mutex.h>
  18 #include <linux/sysfs.h>
  19 #include <linux/mod_devicetable.h>
  20 #include <linux/log2.h>
  21 #include <linux/bitops.h>
  22 #include <linux/jiffies.h>
  23 #include <linux/i2c.h>
  24 #include <linux/i2c/at24.h>
  25
  26 /*
  27  * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
  28  * Differences between different vendor product lines (like Atmel AT24C or
  29  * MicroChip 24LC, etc) won't much matter for typical read/write access.
  30  * There are also I2C RAM chips, likewise interchangeable. One example
  31  * would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
  32  *
  33  * However, misconfiguration can lose data. "Set 16-bit memory address"
  34  * to a part with 8-bit addressing will overwrite data. Writing with too
  35  * big a page size also loses data. And it's not safe to assume that the
  36  * conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
  37  * uses 0x51, for just one example.
  38  *
  39  * Accordingly, explicit board-specific configuration data should be used
  40  * in almost all cases. (One partial exception is an SMBus used to access
  41  * "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
  42  *
  43  * So this driver uses "new style" I2C driver binding, expecting to be
  44  * told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
  45  * similar kernel-resident tables; or, configuration data coming from
  46  * a bootloader.
  47  *
  48  * Other than binding model, current differences from "eeprom" driver are
  49  * that this one handles write access and isn't restricted to 24c02 devices.
  50  * It also handles larger devices (32 kbit and up) with two-byte addresses,
  51  * which won't work on pure SMBus systems.
  52  */
  53
  54 struct at24_data {
  55         struct at24_platform_data chip;
  56         struct memory_accessor macc;
  57         int use_smbus;
  58
  59         /*
  60          * Lock protects against activities from other Linux tasks,
  61          * but not from changes by other I2C masters.
  62          */
  63         struct mutex lock;
  64         struct bin_attribute bin;
  65
  66         u8 *writebuf;
  67         unsigned write_max;
  68         unsigned num_addresses;
  69
  70         /*
  71          * Some chips tie up multiple I2C addresses; dummy devices reserve
  72          * them for us, and we'll use them with SMBus calls.
  73          */
  74         struct i2c_client *client[];
  75 };
  76
  77 /*
  78  * This parameter is to help this driver avoid blocking other drivers out
  79  * of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
  80  * clock, one 256 byte read takes about 1/43 second which is excessive;
  81  * but the 1/170 second it takes at 400 kHz may be quite reasonable; and
  82  * at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
  83  *
  84  * This value is forced to be a power of two so that writes align on pages.
  85  */
  86 static unsigned io_limit = 128;
  87 module_param(io_limit, uint, 0);
  88 MODULE_PARM_DESC(io_limit, "Maximum bytes per I/O (default 128)");
  89
  90 /*
  91  * Specs often allow 5 msec for a page write, sometimes 20 msec;
  92  * it's important to recover from write timeouts.
  93  */
  94 static unsigned write_timeout = 25;
  95 module_param(write_timeout, uint, 0);
  96 MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
  97
  98 #define AT24_SIZE_BYTELEN 5
  99 #define AT24_SIZE_FLAGS 8
 100
 101 #define AT24_BITMASK(x) (BIT(x) - 1)
 102
 103 /* create non-zero magic value for given eeprom parameters */
 104 #define AT24_DEVICE_MAGIC(_len, _flags)                 \
 105         ((1 << AT24_SIZE_FLAGS | (_flags))              \
 106             << AT24_SIZE_BYTELEN | ilog2(_len))
 107
 108 static const struct i2c_device_id at24_ids[] = {
 109         /* needs 8 addresses as A0-A2 are ignored */
 110         { "24c00", AT24_DEVICE_MAGIC(128 / 8, AT24_FLAG_TAKE8ADDR) },
 111         /* old variants can't be handled with this generic entry! */
 112         { "24c01", AT24_DEVICE_MAGIC(1024 / 8, 0) },
 113         { "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) },
 114         /* spd is a 24c02 in memory DIMMs */
 115         { "spd", AT24_DEVICE_MAGIC(2048 / 8,
 116                 AT24_FLAG_READONLY | AT24_FLAG_IRUGO) },
 117         { "24c04", AT24_DEVICE_MAGIC(4096 / 8, 0) },
 118         /* 24rf08 quirk is handled at i2c-core */
 119         { "24c08", AT24_DEVICE_MAGIC(8192 / 8, 0) },
 120         { "24c16", AT24_DEVICE_MAGIC(16384 / 8, 0) },
 121         { "24c32", AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16) },
 122         { "24c64", AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16) },
 123         { "24c128", AT24_DEVICE_MAGIC(131072 / 8, AT24_FLAG_ADDR16) },
 124         { "24c256", AT24_DEVICE_MAGIC(262144 / 8, AT24_FLAG_ADDR16) },
 125         { "24c512", AT24_DEVICE_MAGIC(524288 / 8, AT24_FLAG_ADDR16) },
 126         { "24c1024", AT24_DEVICE_MAGIC(1048576 / 8, AT24_FLAG_ADDR16) },
 127         { "at24", 0 },
 128         { /* END OF LIST */ }
 129 };
 130 MODULE_DEVICE_TABLE(i2c, at24_ids);
 131
 132 /*-------------------------------------------------------------------------*/
 133
 134 /*
 135  * This routine supports chips which consume multiple I2C addresses. It
 136  * computes the addressing information to be used for a given r/w request.
 137  * Assumes that sanity checks for offset happened at sysfs-layer.
 138  */
 139 static struct i2c_client *at24_translate_offset(struct at24_data *at24,
 140                 unsigned *offset)
 141 {
 142         unsigned i;
 143
 144         if (at24->chip.flags & AT24_FLAG_ADDR16) {
 145                 i = *offset >> 16;
 146                 *offset &= 0xffff;
 147         } else {
 148                 i = *offset >> 8;
 149                 *offset &= 0xff;
 150         }
 151
 152         return at24->client[i];
 153 }
 154
 155 static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,
 156                 unsigned offset, size_t count)
 157 {
 158         struct i2c_msg msg[2];
 159         u8 msgbuf[2];
 160         struct i2c_client *client;
 161         unsigned long timeout, read_time;
 162         int status, i;
 163
 164         memset(msg, 0, sizeof(msg));
 165
 166         /*
 167          * REVISIT some multi-address chips don't rollover page reads to
 168          * the next slave address, so we may need to truncate the count.
 169          * Those chips might need another quirk flag.
 170          *
 171          * If the real hardware used four adjacent 24c02 chips and that
 172          * were misconfigured as one 24c08, that would be a similar effect:
 173          * one "eeprom" file not four, but larger reads would fail when
 174          * they crossed certain pages.
 175          */
 176
 177         /*
 178          * Slave address and byte offset derive from the offset. Always
 179          * set the byte address; on a multi-master board, another master
 180          * may have changed the chip's "current" address pointer.
 181          */
 182         client = at24_translate_offset(at24, &offset);
 183
 184         if (count > io_limit)
 185                 count = io_limit;
 186
 187         switch (at24->use_smbus) {
 188         case I2C_SMBUS_I2C_BLOCK_DATA:
 189                 /* Smaller eeproms can work given some SMBus extension calls */
 190                 if (count > I2C_SMBUS_BLOCK_MAX)
 191                         count = I2C_SMBUS_BLOCK_MAX;
 192                 break;
 193         case I2C_SMBUS_WORD_DATA:
 194                 count = 2;
 195                 break;
 196         case I2C_SMBUS_BYTE_DATA:
 197                 count = 1;
 198                 break;
 199         default:
 200                 /*
 201                  * When we have a better choice than SMBus calls, use a
 202                  * combined I2C message. Write address; then read up to
 203                  * io_limit data bytes. Note that read page rollover helps us
 204                  * here (unlike writes). msgbuf is u8 and will cast to our
 205                  * needs.
 206                  */
 207                 i = 0;
 208                 if (at24->chip.flags & AT24_FLAG_ADDR16)
 209                         msgbuf[i++] = offset >> 8;
 210                 msgbuf[i++] = offset;
 211
 212                 msg[0].addr = client->addr;
 213                 msg[0].buf = msgbuf;
 214                 msg[0].len = i;
 215
 216                 msg[1].addr = client->addr;
 217                 msg[1].flags = I2C_M_RD;
 218                 msg[1].buf = buf;
 219                 msg[1].len = count;
 220         }
 221
 222         /*
 223          * Reads fail if the previous write didn't complete yet. We may
 224          * loop a few times until this one succeeds, waiting at least
 225          * long enough for one entire page write to work.
 226          */
 227         timeout = jiffies + msecs_to_jiffies(write_timeout);
 228         do {
 229                 read_time = jiffies;
 230                 switch (at24->use_smbus) {
 231                 case I2C_SMBUS_I2C_BLOCK_DATA:
 232                         status = i2c_smbus_read_i2c_block_data(client, offset,
 233                                         count, buf);
 234                         break;
 235                 case I2C_SMBUS_WORD_DATA:
 236                         status = i2c_smbus_read_word_data(client, offset);
 237                         if (status >= 0) {
 238                                 buf[0] = status & 0xff;
 239                                 buf[1] = status >> 8;
 240                                 status = count;
 241                         }
 242                         break;
 243                 case I2C_SMBUS_BYTE_DATA:
 244                         status = i2c_smbus_read_byte_data(client, offset);
 245                         if (status >= 0) {
 246                                 buf[0] = status;
 247                                 status = count;
 248                         }
 249                         break;
 250                 default:
 251                         status = i2c_transfer(client->adapter, msg, 2);
 252                         if (status == 2)
 253                                 status = count;
 254                 }
 255                 dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
 256                                 count, offset, status, jiffies);
 257
 258                 if (status == count)
 259                         return count;
 260
 261                 /* REVISIT: at HZ=100, this is sloooow */
 262                 msleep(1);
 263         } while (time_before(read_time, timeout));
 264
 265         return -ETIMEDOUT;
 266 }
 267
 268 static ssize_t at24_read(struct at24_data *at24,
 269                 char *buf, loff_t off, size_t count)
 270 {
 271         ssize_t retval = 0;
 272
 273         if (unlikely(!count))
 274                 return count;
 275
 276         /*
 277          * Read data from chip, protecting against concurrent updates
 278          * from this host, but not from other I2C masters.
 279          */
 280         mutex_lock(&at24->lock);
 281
 282         while (count) {
 283                 ssize_t status;
 284
 285                 status = at24_eeprom_read(at24, buf, off, count);
 286                 if (status <= 0) {
 287                         if (retval == 0)
 288                                 retval = status;
 289                         break;
 290                 }
 291                 buf += status;
 292                 off += status;
 293                 count -= status;
 294                 retval += status;
 295         }
 296
 297         mutex_unlock(&at24->lock);
 298
 299         return retval;
 300 }
 301
 302 static ssize_t at24_bin_read(struct file *filp, struct kobject *kobj,
 303                 struct bin_attribute *attr,
 304                 char *buf, loff_t off, size_t count)
 305 {
 306         struct at24_data *at24;
 307
 308         at24 = dev_get_drvdata(container_of(kobj, struct device, kobj));
 309         return at24_read(at24, buf, off, count);
 310 }
 311
 312
 313 /*
 314  * Note that if the hardware write-protect pin is pulled high, the whole
 315  * chip is normally write protected. But there are plenty of product
 316  * variants here, including OTP fuses and partial chip protect.
 317  *
 318  * We only use page mode writes; the alternative is sloooow. This routine
 319  * writes at most one page.
 320  */
 321 static ssize_t at24_eeprom_write(struct at24_data *at24, const char *buf,
 322                 unsigned offset, size_t count)
 323 {
 324         struct i2c_client *client;
 325         struct i2c_msg msg;
 326         ssize_t status;
 327         unsigned long timeout, write_time;
 328         unsigned next_page;
 329
 330         /* Get corresponding I2C address and adjust offset */
 331         client = at24_translate_offset(at24, &offset);
 332
 333         /* write_max is at most a page */
 334         if (count > at24->write_max)
 335                 count = at24->write_max;
 336
 337         /* Never roll over backwards, to the start of this page */
 338         next_page = roundup(offset + 1, at24->chip.page_size);
 339         if (offset + count > next_page)
 340                 count = next_page - offset;
 341
 342         /* If we'll use I2C calls for I/O, set up the message */
 343         if (!at24->use_smbus) {
 344                 int i = 0;
 345
 346                 msg.addr = client->addr;
 347                 msg.flags = 0;
 348
 349                 /* msg.buf is u8 and casts will mask the values */
 350                 msg.buf = at24->writebuf;
 351                 if (at24->chip.flags & AT24_FLAG_ADDR16)
 352                         msg.buf[i++] = offset >> 8;
 353
 354                 msg.buf[i++] = offset;
 355                 memcpy(&msg.buf[i], buf, count);
 356                 msg.len = i + count;
 357         }
 358
 359         /*
 360          * Writes fail if the previous one didn't complete yet. We may
 361          * loop a few times until this one succeeds, waiting at least
 362          * long enough for one entire page write to work.
 363          */
 364         timeout = jiffies + msecs_to_jiffies(write_timeout);
 365         do {
 366                 write_time = jiffies;
 367                 if (at24->use_smbus) {
 368                         status = i2c_smbus_write_i2c_block_data(client,
 369                                         offset, count, buf);
 370                         if (status == 0)
 371                                 status = count;
 372                 } else {
 373                         status = i2c_transfer(client->adapter, &msg, 1);
 374                         if (status == 1)
 375                                 status = count;
 376                 }
 377                 dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n",
 378                                 count, offset, status, jiffies);
 379
 380                 if (status == count)
 381                         return count;
 382
 383                 /* REVISIT: at HZ=100, this is sloooow */
 384                 msleep(1);
 385         } while (time_before(write_time, timeout));
 386
 387         return -ETIMEDOUT;
 388 }
 389
 390 static ssize_t at24_write(struct at24_data *at24, const char *buf, loff_t off,
 391                           size_t count)
 392 {
 393         ssize_t retval = 0;
 394
 395         if (unlikely(!count))
 396                 return count;
 397
 398         /*
 399          * Write data to chip, protecting against concurrent updates
 400          * from this host, but not from other I2C masters.
 401          */
 402         mutex_lock(&at24->lock);
 403
 404         while (count) {
 405                 ssize_t status;
 406
 407                 status = at24_eeprom_write(at24, buf, off, count);
 408                 if (status <= 0) {
 409                         if (retval == 0)
 410                                 retval = status;
 411                         break;
 412                 }
 413                 buf += status;
 414                 off += status;
 415                 count -= status;
 416                 retval += status;
 417         }
 418
 419         mutex_unlock(&at24->lock);
 420
 421         return retval;
 422 }
 423
 424 static ssize_t at24_bin_write(struct file *filp, struct kobject *kobj,
 425                 struct bin_attribute *attr,
 426                 char *buf, loff_t off, size_t count)
 427 {
 428         struct at24_data *at24;
 429
 430         at24 = dev_get_drvdata(container_of(kobj, struct device, kobj));
 431         return at24_write(at24, buf, off, count);
 432 }
 433
 434 /*-------------------------------------------------------------------------*/
 435
 436 /*
 437  * This lets other kernel code access the eeprom data. For example, it
 438  * might hold a board's Ethernet address, or board-specific calibration
 439  * data generated on the manufacturing floor.
 440  */
 441
 442 static ssize_t at24_macc_read(struct memory_accessor *macc, char *buf,
 443                          off_t offset, size_t count)
 444 {
 445         struct at24_data *at24 = container_of(macc, struct at24_data, macc);
 446
 447         return at24_read(at24, buf, offset, count);
 448 }
 449
 450 static ssize_t at24_macc_write(struct memory_accessor *macc, const char *buf,
 451                           off_t offset, size_t count)
 452 {
 453         struct at24_data *at24 = container_of(macc, struct at24_data, macc);
 454
 455         return at24_write(at24, buf, offset, count);
 456 }
 457
 458 /*-------------------------------------------------------------------------*/
 459
 460 static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 461 {
 462         struct at24_platform_data chip;
 463         bool writable;
 464         int use_smbus = 0;
 465         struct at24_data *at24;
 466         int err;
 467         unsigned i, num_addresses;
 468         kernel_ulong_t magic;
 469
 470         if (client->dev.platform_data) {
 471                 chip = *(struct at24_platform_data *)client->dev.platform_data;
 472         } else {
 473                 if (!id->driver_data) {
 474                         err = -ENODEV;
 475                         goto err_out;
 476                 }
 477                 magic = id->driver_data;
 478                 chip.byte_len = BIT(magic & AT24_BITMASK(AT24_SIZE_BYTELEN));
 479                 magic >>= AT24_SIZE_BYTELEN;
 480                 chip.flags = magic & AT24_BITMASK(AT24_SIZE_FLAGS);
 481                 /*
 482                  * This is slow, but we can't know all eeproms, so we better
 483                  * play safe. Specifying custom eeprom-types via platform_data
 484                  * is recommended anyhow.
 485                  */
 486                 chip.page_size = 1;
 487
 488                 chip.setup = NULL;
 489                 chip.context = NULL;
 490         }
 491
 492         if (!is_power_of_2(chip.byte_len))
 493                 dev_warn(&client->dev,
 494                         "byte_len looks suspicious (no power of 2)!\n");
 495         if (!is_power_of_2(chip.page_size))
 496                 dev_warn(&client->dev,
 497                         "page_size looks suspicious (no power of 2)!\n");
 498
 499         /* Use I2C operations unless we're stuck with SMBus extensions. */
 500         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
 501                 if (chip.flags & AT24_FLAG_ADDR16) {
 502                         err = -EPFNOSUPPORT;
 503                         goto err_out;
 504                 }
 505                 if (i2c_check_functionality(client->adapter,
 506                                 I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
 507                         use_smbus = I2C_SMBUS_I2C_BLOCK_DATA;
 508                 } else if (i2c_check_functionality(client->adapter,
 509                                 I2C_FUNC_SMBUS_READ_WORD_DATA)) {
 510                         use_smbus = I2C_SMBUS_WORD_DATA;
 511                 } else if (i2c_check_functionality(client->adapter,
 512                                 I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
 513                         use_smbus = I2C_SMBUS_BYTE_DATA;
 514                 } else {
 515                         err = -EPFNOSUPPORT;
 516                         goto err_out;
 517                 }
 518         }
 519
 520         if (chip.flags & AT24_FLAG_TAKE8ADDR)
 521                 num_addresses = 8;
 522         else
 523                 num_addresses = DIV_ROUND_UP(chip.byte_len,
 524                         (chip.flags & AT24_FLAG_ADDR16) ? 65536 : 256);
 525
 526         at24 = kzalloc(sizeof(struct at24_data) +
 527                 num_addresses * sizeof(struct i2c_client *), GFP_KERNEL);
 528         if (!at24) {
 529                 err = -ENOMEM;
 530                 goto err_out;
 531         }
 532
 533         mutex_init(&at24->lock);
 534         at24->use_smbus = use_smbus;
 535         at24->chip = chip;
 536         at24->num_addresses = num_addresses;
 537
 538         /*
 539          * Export the EEPROM bytes through sysfs, since that's convenient.
 540          * By default, only root should see the data (maybe passwords etc)
 541          */
 542         sysfs_bin_attr_init(&at24->bin);
 543         at24->bin.attr.name = "eeprom";
 544         at24->bin.attr.mode = chip.flags & AT24_FLAG_IRUGO ? S_IRUGO : S_IRUSR;
 545         at24->bin.read = at24_bin_read;
 546         at24->bin.size = chip.byte_len;
 547
 548         at24->macc.read = at24_macc_read;
 549
 550         writable = !(chip.flags & AT24_FLAG_READONLY);
 551         if (writable) {
 552                 if (!use_smbus || i2c_check_functionality(client->adapter,
 553                                 I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
 554
 555                         unsigned write_max = chip.page_size;
 556
 557                         at24->macc.write = at24_macc_write;
 558
 559                         at24->bin.write = at24_bin_write;
 560                         at24->bin.attr.mode |= S_IWUSR;
 561
 562                         if (write_max > io_limit)
 563                                 write_max = io_limit;
 564                         if (use_smbus && write_max > I2C_SMBUS_BLOCK_MAX)
 565                                 write_max = I2C_SMBUS_BLOCK_MAX;
 566                         at24->write_max = write_max;
 567
 568                         /* buffer (data + address at the beginning) */
 569                         at24->writebuf = kmalloc(write_max + 2, GFP_KERNEL);
 570                         if (!at24->writebuf) {
 571                                 err = -ENOMEM;
 572                                 goto err_struct;
 573                         }
 574                 } else {
 575                         dev_warn(&client->dev,
 576                                 "cannot write due to controller restrictions.");
 577                 }
 578         }
 579
 580         at24->client[0] = client;
 581
 582         /* use dummy devices for multiple-address chips */
 583         for (i = 1; i < num_addresses; i++) {
 584                 at24->client[i] = i2c_new_dummy(client->adapter,
 585                                         client->addr + i);
 586                 if (!at24->client[i]) {
 587                         dev_err(&client->dev, "address 0x%02x unavailable\n",
 588                                         client->addr + i);
 589                         err = -EADDRINUSE;
 590                         goto err_clients;
 591                 }
 592         }
 593
 594         err = sysfs_create_bin_file(&client->dev.kobj, &at24->bin);
 595         if (err)
 596                 goto err_clients;
 597
 598         i2c_set_clientdata(client, at24);
 599
 600         dev_info(&client->dev, "%zu byte %s EEPROM %s\n",
 601                 at24->bin.size, client->name,
 602                 writable ? "(writable)" : "(read-only)");
 603         if (use_smbus == I2C_SMBUS_WORD_DATA ||
 604             use_smbus == I2C_SMBUS_BYTE_DATA) {
 605                 dev_notice(&client->dev, "Falling back to %s reads, "
 606                            "performance will suffer\n", use_smbus ==
 607                            I2C_SMBUS_WORD_DATA ? "word" : "byte");
 608         }
 609         dev_dbg(&client->dev,
 610                 "page_size %d, num_addresses %d, write_max %d, use_smbus %d\n",
 611                 chip.page_size, num_addresses,
 612                 at24->write_max, use_smbus);
 613
 614         /* export data to kernel code */
 615         if (chip.setup)
 616                 chip.setup(&at24->macc, chip.context);
 617
 618         return 0;
 619
 620 err_clients:
 621         for (i = 1; i < num_addresses; i++)
 622                 if (at24->client[i])
 623                         i2c_unregister_device(at24->client[i]);
 624
 625         kfree(at24->writebuf);
 626 err_struct:
 627         kfree(at24);
 628 err_out:
 629         dev_dbg(&client->dev, "probe error %d\n", err);
 630         return err;
 631 }
 632
 633 static int __devexit at24_remove(struct i2c_client *client)
 634 {
 635         struct at24_data *at24;
 636         int i;
 637
 638         at24 = i2c_get_clientdata(client);
 639         sysfs_remove_bin_file(&client->dev.kobj, &at24->bin);
 640
 641         for (i = 1; i < at24->num_addresses; i++)
 642                 i2c_unregister_device(at24->client[i]);
 643
 644         kfree(at24->writebuf);
 645         kfree(at24);
 646         return 0;
 647 }
 648
 649 /*-------------------------------------------------------------------------*/
 650
 651 static struct i2c_driver at24_driver = {
 652         .driver = {
 653                 .name = "at24",
 654                 .owner = THIS_MODULE,
 655         },
 656         .probe = at24_probe,
 657         .remove = __devexit_p(at24_remove),
 658         .id_table = at24_ids,
 659 };
 660
 661 static int __init at24_init(void)
 662 {
 663         io_limit = rounddown_pow_of_two(io_limit);
 664         return i2c_add_driver(&at24_driver);
 665 }
 666 module_init(at24_init);
 667
 668 static void __exit at24_exit(void)
 669 {
 670         i2c_del_driver(&at24_driver);
 671 }
 672 module_exit(at24_exit);
 673
 674 MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
 675 MODULE_AUTHOR("David Brownell and Wolfram Sang");
 676 MODULE_LICENSE("GPL");