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/of.h>
  24 #include <linux/i2c.h>
  25 #include <linux/platform_data/at24.h>
  26
  27 /*
  28  * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
  29  * Differences between different vendor product lines (like Atmel AT24C or
  30  * MicroChip 24LC, etc) won't much matter for typical read/write access.
  31  * There are also I2C RAM chips, likewise interchangeable. One example
  32  * would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
  33  *
  34  * However, misconfiguration can lose data. "Set 16-bit memory address"
  35  * to a part with 8-bit addressing will overwrite data. Writing with too
  36  * big a page size also loses data. And it's not safe to assume that the
  37  * conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
  38  * uses 0x51, for just one example.
  39  *
  40  * Accordingly, explicit board-specific configuration data should be used
  41  * in almost all cases. (One partial exception is an SMBus used to access
  42  * "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
  43  *
  44  * So this driver uses "new style" I2C driver binding, expecting to be
  45  * told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
  46  * similar kernel-resident tables; or, configuration data coming from
  47  * a bootloader.
  48  *
  49  * Other than binding model, current differences from "eeprom" driver are
  50  * that this one handles write access and isn't restricted to 24c02 devices.
  51  * It also handles larger devices (32 kbit and up) with two-byte addresses,
  52  * which won't work on pure SMBus systems.
  53  */
  54
  55 struct at24_data {
  56         struct at24_platform_data chip;
  57         struct memory_accessor macc;
  58         int use_smbus;
  59         int use_smbus_write;
  60
  61         /*
  62          * Lock protects against activities from other Linux tasks,
  63          * but not from changes by other I2C masters.
  64          */
  65         struct mutex lock;
  66         struct bin_attribute bin;
  67
  68         u8 *writebuf;
  69         unsigned write_max;
  70         unsigned num_addresses;
  71
  72         /*
  73          * Some chips tie up multiple I2C addresses; dummy devices reserve
  74          * them for us, and we'll use them with SMBus calls.
  75          */
  76         struct i2c_client *client[];
  77 };
  78
  79 /*
  80  * This parameter is to help this driver avoid blocking other drivers out
  81  * of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
  82  * clock, one 256 byte read takes about 1/43 second which is excessive;
  83  * but the 1/170 second it takes at 400 kHz may be quite reasonable; and
  84  * at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
  85  *
  86  * This value is forced to be a power of two so that writes align on pages.
  87  */
  88 static unsigned io_limit = 128;
  89 module_param(io_limit, uint, 0);
  90 MODULE_PARM_DESC(io_limit, "Maximum bytes per I/O (default 128)");
  91
  92 /*
  93  * Specs often allow 5 msec for a page write, sometimes 20 msec;
  94  * it's important to recover from write timeouts.
  95  */
  96 static unsigned write_timeout = 25;
  97 module_param(write_timeout, uint, 0);
  98 MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
  99
 100 #define AT24_SIZE_BYTELEN 5
 101 #define AT24_SIZE_FLAGS 8
 102
 103 #define AT24_BITMASK(x) (BIT(x) - 1)
 104
 105 /* create non-zero magic value for given eeprom parameters */
 106 #define AT24_DEVICE_MAGIC(_len, _flags)                 \
 107         ((1 << AT24_SIZE_FLAGS | (_flags))              \
 108             << AT24_SIZE_BYTELEN | ilog2(_len))
 109
 110 static const struct i2c_device_id at24_ids[] = {
 111         /* needs 8 addresses as A0-A2 are ignored */
 112         { "24c00", AT24_DEVICE_MAGIC(128 / 8, AT24_FLAG_TAKE8ADDR) },
 113         /* old variants can't be handled with this generic entry! */
 114         { "24c01", AT24_DEVICE_MAGIC(1024 / 8, 0) },
 115         { "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) },
 116         /* spd is a 24c02 in memory DIMMs */
 117         { "spd", AT24_DEVICE_MAGIC(2048 / 8,
 118                 AT24_FLAG_READONLY | AT24_FLAG_IRUGO) },
 119         { "24c04", AT24_DEVICE_MAGIC(4096 / 8, 0) },
 120         /* 24rf08 quirk is handled at i2c-core */
 121         { "24c08", AT24_DEVICE_MAGIC(8192 / 8, 0) },
 122         { "24c16", AT24_DEVICE_MAGIC(16384 / 8, 0) },
 123         { "24c32", AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16) },
 124         { "24c64", AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16) },
 125         { "24c128", AT24_DEVICE_MAGIC(131072 / 8, AT24_FLAG_ADDR16) },
 126         { "24c256", AT24_DEVICE_MAGIC(262144 / 8, AT24_FLAG_ADDR16) },
 127         { "24c512", AT24_DEVICE_MAGIC(524288 / 8, AT24_FLAG_ADDR16) },
 128         { "24c1024", AT24_DEVICE_MAGIC(1048576 / 8, AT24_FLAG_ADDR16) },
 129         { "at24", 0 },
 130         { /* END OF LIST */ }
 131 };
 132 MODULE_DEVICE_TABLE(i2c, at24_ids);
 133
 134 /*-------------------------------------------------------------------------*/
 135
 136 /*
 137  * This routine supports chips which consume multiple I2C addresses. It
 138  * computes the addressing information to be used for a given r/w request.
 139  * Assumes that sanity checks for offset happened at sysfs-layer.
 140  */
 141 static struct i2c_client *at24_translate_offset(struct at24_data *at24,
 142                 unsigned *offset)
 143 {
 144         unsigned i;
 145
 146         if (at24->chip.flags & AT24_FLAG_ADDR16) {
 147                 i = *offset >> 16;
 148                 *offset &= 0xffff;
 149         } else {
 150                 i = *offset >> 8;
 151                 *offset &= 0xff;
 152         }
 153
 154         return at24->client[i];
 155 }
 156
 157 static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,
 158                 unsigned offset, size_t count)
 159 {
 160         struct i2c_msg msg[2];
 161         u8 msgbuf[2];
 162         struct i2c_client *client;
 163         unsigned long timeout, read_time;
 164         int status, i;
 165
 166         memset(msg, 0, sizeof(msg));
 167
 168         /*
 169          * REVISIT some multi-address chips don't rollover page reads to
 170          * the next slave address, so we may need to truncate the count.
 171          * Those chips might need another quirk flag.
 172          *
 173          * If the real hardware used four adjacent 24c02 chips and that
 174          * were misconfigured as one 24c08, that would be a similar effect:
 175          * one "eeprom" file not four, but larger reads would fail when
 176          * they crossed certain pages.
 177          */
 178
 179         /*
 180          * Slave address and byte offset derive from the offset. Always
 181          * set the byte address; on a multi-master board, another master
 182          * may have changed the chip's "current" address pointer.
 183          */
 184         client = at24_translate_offset(at24, &offset);
 185
 186         if (count > io_limit)
 187                 count = io_limit;
 188
 189         if (at24->use_smbus) {
 190                 /* Smaller eeproms can work given some SMBus extension calls */
 191                 if (count > I2C_SMBUS_BLOCK_MAX)
 192                         count = I2C_SMBUS_BLOCK_MAX;
 193         } else {
 194                 /*
 195                  * When we have a better choice than SMBus calls, use a
 196                  * combined I2C message. Write address; then read up to
 197                  * io_limit data bytes. Note that read page rollover helps us
 198                  * here (unlike writes). msgbuf is u8 and will cast to our
 199                  * needs.
 200                  */
 201                 i = 0;
 202                 if (at24->chip.flags & AT24_FLAG_ADDR16)
 203                         msgbuf[i++] = offset >> 8;
 204                 msgbuf[i++] = offset;
 205
 206                 msg[0].addr = client->addr;
 207                 msg[0].buf = msgbuf;
 208                 msg[0].len = i;
 209
 210                 msg[1].addr = client->addr;
 211                 msg[1].flags = I2C_M_RD;
 212                 msg[1].buf = buf;
 213                 msg[1].len = count;
 214         }
 215
 216         /*
 217          * Reads fail if the previous write didn't complete yet. We may
 218          * loop a few times until this one succeeds, waiting at least
 219          * long enough for one entire page write to work.
 220          */
 221         timeout = jiffies + msecs_to_jiffies(write_timeout);
 222         do {
 223                 read_time = jiffies;
 224                 if (at24->use_smbus) {
 225                         status = i2c_smbus_read_i2c_block_data_or_emulated(client, offset,
 226                                                                            count, buf);
 227                 } else {
 228                         status = i2c_transfer(client->adapter, msg, 2);
 229                         if (status == 2)
 230                                 status = count;
 231                 }
 232                 dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
 233                                 count, offset, status, jiffies);
 234
 235                 if (status == count)
 236                         return count;
 237
 238                 /* REVISIT: at HZ=100, this is sloooow */
 239                 msleep(1);
 240         } while (time_before(read_time, timeout));
 241
 242         return -ETIMEDOUT;
 243 }
 244
 245 static ssize_t at24_read(struct at24_data *at24,
 246                 char *buf, loff_t off, size_t count)
 247 {
 248         ssize_t retval = 0;
 249
 250         if (unlikely(!count))
 251                 return count;
 252
 253         /*
 254          * Read data from chip, protecting against concurrent updates
 255          * from this host, but not from other I2C masters.
 256          */
 257         mutex_lock(&at24->lock);
 258
 259         while (count) {
 260                 ssize_t status;
 261
 262                 status = at24_eeprom_read(at24, buf, off, count);
 263                 if (status <= 0) {
 264                         if (retval == 0)
 265                                 retval = status;
 266                         break;
 267                 }
 268                 buf += status;
 269                 off += status;
 270                 count -= status;
 271                 retval += status;
 272         }
 273
 274         mutex_unlock(&at24->lock);
 275
 276         return retval;
 277 }
 278
 279 static ssize_t at24_bin_read(struct file *filp, struct kobject *kobj,
 280                 struct bin_attribute *attr,
 281                 char *buf, loff_t off, size_t count)
 282 {
 283         struct at24_data *at24;
 284
 285         at24 = dev_get_drvdata(container_of(kobj, struct device, kobj));
 286         return at24_read(at24, buf, off, count);
 287 }
 288
 289
 290 /*
 291  * Note that if the hardware write-protect pin is pulled high, the whole
 292  * chip is normally write protected. But there are plenty of product
 293  * variants here, including OTP fuses and partial chip protect.
 294  *
 295  * We only use page mode writes; the alternative is sloooow. This routine
 296  * writes at most one page.
 297  */
 298 static ssize_t at24_eeprom_write(struct at24_data *at24, const char *buf,
 299                 unsigned offset, size_t count)
 300 {
 301         struct i2c_client *client;
 302         struct i2c_msg msg;
 303         ssize_t status = 0;
 304         unsigned long timeout, write_time;
 305         unsigned next_page;
 306
 307         /* Get corresponding I2C address and adjust offset */
 308         client = at24_translate_offset(at24, &offset);
 309
 310         /* write_max is at most a page */
 311         if (count > at24->write_max)
 312                 count = at24->write_max;
 313
 314         /* Never roll over backwards, to the start of this page */
 315         next_page = roundup(offset + 1, at24->chip.page_size);
 316         if (offset + count > next_page)
 317                 count = next_page - offset;
 318
 319         /* If we'll use I2C calls for I/O, set up the message */
 320         if (!at24->use_smbus) {
 321                 int i = 0;
 322
 323                 msg.addr = client->addr;
 324                 msg.flags = 0;
 325
 326                 /* msg.buf is u8 and casts will mask the values */
 327                 msg.buf = at24->writebuf;
 328                 if (at24->chip.flags & AT24_FLAG_ADDR16)
 329                         msg.buf[i++] = offset >> 8;
 330
 331                 msg.buf[i++] = offset;
 332                 memcpy(&msg.buf[i], buf, count);
 333                 msg.len = i + count;
 334         }
 335
 336         /*
 337          * Writes fail if the previous one didn't complete yet. We may
 338          * loop a few times until this one succeeds, waiting at least
 339          * long enough for one entire page write to work.
 340          */
 341         timeout = jiffies + msecs_to_jiffies(write_timeout);
 342         do {
 343                 write_time = jiffies;
 344                 if (at24->use_smbus_write) {
 345                         switch (at24->use_smbus_write) {
 346                         case I2C_SMBUS_I2C_BLOCK_DATA:
 347                                 status = i2c_smbus_write_i2c_block_data(client,
 348                                                 offset, count, buf);
 349                                 break;
 350                         case I2C_SMBUS_BYTE_DATA:
 351                                 status = i2c_smbus_write_byte_data(client,
 352                                                 offset, buf[0]);
 353                                 break;
 354                         }
 355
 356                         if (status == 0)
 357                                 status = count;
 358                 } else {
 359                         status = i2c_transfer(client->adapter, &msg, 1);
 360                         if (status == 1)
 361                                 status = count;
 362                 }
 363                 dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n",
 364                                 count, offset, status, jiffies);
 365
 366                 if (status == count)
 367                         return count;
 368
 369                 /* REVISIT: at HZ=100, this is sloooow */
 370                 msleep(1);
 371         } while (time_before(write_time, timeout));
 372
 373         return -ETIMEDOUT;
 374 }
 375
 376 static ssize_t at24_write(struct at24_data *at24, const char *buf, loff_t off,
 377                           size_t count)
 378 {
 379         ssize_t retval = 0;
 380
 381         if (unlikely(!count))
 382                 return count;
 383
 384         /*
 385          * Write data to chip, protecting against concurrent updates
 386          * from this host, but not from other I2C masters.
 387          */
 388         mutex_lock(&at24->lock);
 389
 390         while (count) {
 391                 ssize_t status;
 392
 393                 status = at24_eeprom_write(at24, buf, off, count);
 394                 if (status <= 0) {
 395                         if (retval == 0)
 396                                 retval = status;
 397                         break;
 398                 }
 399                 buf += status;
 400                 off += status;
 401                 count -= status;
 402                 retval += status;
 403         }
 404
 405         mutex_unlock(&at24->lock);
 406
 407         return retval;
 408 }
 409
 410 static ssize_t at24_bin_write(struct file *filp, struct kobject *kobj,
 411                 struct bin_attribute *attr,
 412                 char *buf, loff_t off, size_t count)
 413 {
 414         struct at24_data *at24;
 415
 416         at24 = dev_get_drvdata(container_of(kobj, struct device, kobj));
 417         return at24_write(at24, buf, off, count);
 418 }
 419
 420 /*-------------------------------------------------------------------------*/
 421
 422 /*
 423  * This lets other kernel code access the eeprom data. For example, it
 424  * might hold a board's Ethernet address, or board-specific calibration
 425  * data generated on the manufacturing floor.
 426  */
 427
 428 static ssize_t at24_macc_read(struct memory_accessor *macc, char *buf,
 429                          off_t offset, size_t count)
 430 {
 431         struct at24_data *at24 = container_of(macc, struct at24_data, macc);
 432
 433         return at24_read(at24, buf, offset, count);
 434 }
 435
 436 static ssize_t at24_macc_write(struct memory_accessor *macc, const char *buf,
 437                           off_t offset, size_t count)
 438 {
 439         struct at24_data *at24 = container_of(macc, struct at24_data, macc);
 440
 441         return at24_write(at24, buf, offset, count);
 442 }
 443
 444 /*-------------------------------------------------------------------------*/
 445
 446 #ifdef CONFIG_OF
 447 static void at24_get_ofdata(struct i2c_client *client,
 448                 struct at24_platform_data *chip)
 449 {
 450         const __be32 *val;
 451         struct device_node *node = client->dev.of_node;
 452
 453         if (node) {
 454                 if (of_get_property(node, "read-only", NULL))
 455                         chip->flags |= AT24_FLAG_READONLY;
 456                 val = of_get_property(node, "pagesize", NULL);
 457                 if (val)
 458                         chip->page_size = be32_to_cpup(val);
 459         }
 460 }
 461 #else
 462 static void at24_get_ofdata(struct i2c_client *client,
 463                 struct at24_platform_data *chip)
 464 { }
 465 #endif /* CONFIG_OF */
 466
 467 static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 468 {
 469         struct at24_platform_data chip;
 470         bool writable;
 471         int use_smbus = 0;
 472         int use_smbus_write = 0;
 473         struct at24_data *at24;
 474         int err;
 475         unsigned i, num_addresses;
 476         kernel_ulong_t magic;
 477
 478         if (client->dev.platform_data) {
 479                 chip = *(struct at24_platform_data *)client->dev.platform_data;
 480         } else {
 481                 if (!id->driver_data)
 482                         return -ENODEV;
 483
 484                 magic = id->driver_data;
 485                 chip.byte_len = BIT(magic & AT24_BITMASK(AT24_SIZE_BYTELEN));
 486                 magic >>= AT24_SIZE_BYTELEN;
 487                 chip.flags = magic & AT24_BITMASK(AT24_SIZE_FLAGS);
 488                 /*
 489                  * This is slow, but we can't know all eeproms, so we better
 490                  * play safe. Specifying custom eeprom-types via platform_data
 491                  * is recommended anyhow.
 492                  */
 493                 chip.page_size = 1;
 494
 495                 /* update chipdata if OF is present */
 496                 at24_get_ofdata(client, &chip);
 497
 498                 chip.setup = NULL;
 499                 chip.context = NULL;
 500         }
 501
 502         if (!is_power_of_2(chip.byte_len))
 503                 dev_warn(&client->dev,
 504                         "byte_len looks suspicious (no power of 2)!\n");
 505         if (!chip.page_size) {
 506                 dev_err(&client->dev, "page_size must not be 0!\n");
 507                 return -EINVAL;
 508         }
 509         if (!is_power_of_2(chip.page_size))
 510                 dev_warn(&client->dev,
 511                         "page_size looks suspicious (no power of 2)!\n");
 512
 513         /* Use I2C operations unless we're stuck with SMBus extensions. */
 514         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
 515                 if (chip.flags & AT24_FLAG_ADDR16)
 516                         return -EPFNOSUPPORT;
 517
 518                 if (i2c_check_functionality(client->adapter,
 519                                 I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
 520                         use_smbus = I2C_SMBUS_I2C_BLOCK_DATA;
 521                 } else if (i2c_check_functionality(client->adapter,
 522                                 I2C_FUNC_SMBUS_READ_WORD_DATA)) {
 523                         use_smbus = I2C_SMBUS_WORD_DATA;
 524                 } else if (i2c_check_functionality(client->adapter,
 525                                 I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
 526                         use_smbus = I2C_SMBUS_BYTE_DATA;
 527                 } else {
 528                         return -EPFNOSUPPORT;
 529                 }
 530         }
 531
 532         /* Use I2C operations unless we're stuck with SMBus extensions. */
 533         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
 534                 if (i2c_check_functionality(client->adapter,
 535                                 I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
 536                         use_smbus_write = I2C_SMBUS_I2C_BLOCK_DATA;
 537                 } else if (i2c_check_functionality(client->adapter,
 538                                 I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) {
 539                         use_smbus_write = I2C_SMBUS_BYTE_DATA;
 540                         chip.page_size = 1;
 541                 }
 542         }
 543
 544         if (chip.flags & AT24_FLAG_TAKE8ADDR)
 545                 num_addresses = 8;
 546         else
 547                 num_addresses = DIV_ROUND_UP(chip.byte_len,
 548                         (chip.flags & AT24_FLAG_ADDR16) ? 65536 : 256);
 549
 550         at24 = devm_kzalloc(&client->dev, sizeof(struct at24_data) +
 551                 num_addresses * sizeof(struct i2c_client *), GFP_KERNEL);
 552         if (!at24)
 553                 return -ENOMEM;
 554
 555         mutex_init(&at24->lock);
 556         at24->use_smbus = use_smbus;
 557         at24->use_smbus_write = use_smbus_write;
 558         at24->chip = chip;
 559         at24->num_addresses = num_addresses;
 560
 561         /*
 562          * Export the EEPROM bytes through sysfs, since that's convenient.
 563          * By default, only root should see the data (maybe passwords etc)
 564          */
 565         sysfs_bin_attr_init(&at24->bin);
 566         at24->bin.attr.name = "eeprom";
 567         at24->bin.attr.mode = chip.flags & AT24_FLAG_IRUGO ? S_IRUGO : S_IRUSR;
 568         at24->bin.read = at24_bin_read;
 569         at24->bin.size = chip.byte_len;
 570
 571         at24->macc.read = at24_macc_read;
 572
 573         writable = !(chip.flags & AT24_FLAG_READONLY);
 574         if (writable) {
 575                 if (!use_smbus || use_smbus_write) {
 576
 577                         unsigned write_max = chip.page_size;
 578
 579                         at24->macc.write = at24_macc_write;
 580
 581                         at24->bin.write = at24_bin_write;
 582                         at24->bin.attr.mode |= S_IWUSR;
 583
 584                         if (write_max > io_limit)
 585                                 write_max = io_limit;
 586                         if (use_smbus && write_max > I2C_SMBUS_BLOCK_MAX)
 587                                 write_max = I2C_SMBUS_BLOCK_MAX;
 588                         at24->write_max = write_max;
 589
 590                         /* buffer (data + address at the beginning) */
 591                         at24->writebuf = devm_kzalloc(&client->dev,
 592                                 write_max + 2, GFP_KERNEL);
 593                         if (!at24->writebuf)
 594                                 return -ENOMEM;
 595                 } else {
 596                         dev_warn(&client->dev,
 597                                 "cannot write due to controller restrictions.");
 598                 }
 599         }
 600
 601         at24->client[0] = client;
 602
 603         /* use dummy devices for multiple-address chips */
 604         for (i = 1; i < num_addresses; i++) {
 605                 at24->client[i] = i2c_new_dummy(client->adapter,
 606                                         client->addr + i);
 607                 if (!at24->client[i]) {
 608                         dev_err(&client->dev, "address 0x%02x unavailable\n",
 609                                         client->addr + i);
 610                         err = -EADDRINUSE;
 611                         goto err_clients;
 612                 }
 613         }
 614
 615         err = sysfs_create_bin_file(&client->dev.kobj, &at24->bin);
 616         if (err)
 617                 goto err_clients;
 618
 619         i2c_set_clientdata(client, at24);
 620
 621         dev_info(&client->dev, "%zu byte %s EEPROM, %s, %u bytes/write\n",
 622                 at24->bin.size, client->name,
 623                 writable ? "writable" : "read-only", at24->write_max);
 624         if (use_smbus == I2C_SMBUS_WORD_DATA ||
 625             use_smbus == I2C_SMBUS_BYTE_DATA) {
 626                 dev_notice(&client->dev, "Falling back to %s reads, "
 627                            "performance will suffer\n", use_smbus ==
 628                            I2C_SMBUS_WORD_DATA ? "word" : "byte");
 629         }
 630
 631         /* export data to kernel code */
 632         if (chip.setup)
 633                 chip.setup(&at24->macc, chip.context);
 634
 635         return 0;
 636
 637 err_clients:
 638         for (i = 1; i < num_addresses; i++)
 639                 if (at24->client[i])
 640                         i2c_unregister_device(at24->client[i]);
 641
 642         return err;
 643 }
 644
 645 static int at24_remove(struct i2c_client *client)
 646 {
 647         struct at24_data *at24;
 648         int i;
 649
 650         at24 = i2c_get_clientdata(client);
 651         sysfs_remove_bin_file(&client->dev.kobj, &at24->bin);
 652
 653         for (i = 1; i < at24->num_addresses; i++)
 654                 i2c_unregister_device(at24->client[i]);
 655
 656         return 0;
 657 }
 658
 659 /*-------------------------------------------------------------------------*/
 660
 661 static struct i2c_driver at24_driver = {
 662         .driver = {
 663                 .name = "at24",
 664         },
 665         .probe = at24_probe,
 666         .remove = at24_remove,
 667         .id_table = at24_ids,
 668 };
 669
 670 static int __init at24_init(void)
 671 {
 672         if (!io_limit) {
 673                 pr_err("at24: io_limit must not be 0!\n");
 674                 return -EINVAL;
 675         }
 676
 677         io_limit = rounddown_pow_of_two(io_limit);
 678         return i2c_add_driver(&at24_driver);
 679 }
 680 module_init(at24_init);
 681
 682 static void __exit at24_exit(void)
 683 {
 684         i2c_del_driver(&at24_driver);
 685 }
 686 module_exit(at24_exit);
 687
 688 MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
 689 MODULE_AUTHOR("David Brownell and Wolfram Sang");
 690 MODULE_LICENSE("GPL");