drivers/misc/eeprom/at24.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
at24_translate_offset
at24_base_client_dev
at24_adjust_read_count
at24_regmap_read
at24_adjust_write_count
at24_regmap_write
at24_read
at24_write
at24_get_chip_data
at24_make_dummy_client
at24_get_offset_adj
at24_probe
at24_remove
at24_init
at24_exit
   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * at24.c - handle most I2C EEPROMs
   4  *
   5  * Copyright (C) 2005-2007 David Brownell
   6  * Copyright (C) 2008 Wolfram Sang, Pengutronix
   7  */
   8 
   9 #include <linux/kernel.h>
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12 #include <linux/of_device.h>
  13 #include <linux/slab.h>
  14 #include <linux/delay.h>
  15 #include <linux/mutex.h>
  16 #include <linux/mod_devicetable.h>
  17 #include <linux/bitops.h>
  18 #include <linux/jiffies.h>
  19 #include <linux/property.h>
  20 #include <linux/acpi.h>
  21 #include <linux/i2c.h>
  22 #include <linux/nvmem-provider.h>
  23 #include <linux/regmap.h>
  24 #include <linux/pm_runtime.h>
  25 #include <linux/gpio/consumer.h>
  26 
  27 /* Address pointer is 16 bit. */
  28 #define AT24_FLAG_ADDR16        BIT(7)
  29 /* sysfs-entry will be read-only. */
  30 #define AT24_FLAG_READONLY      BIT(6)
  31 /* sysfs-entry will be world-readable. */
  32 #define AT24_FLAG_IRUGO         BIT(5)
  33 /* Take always 8 addresses (24c00). */
  34 #define AT24_FLAG_TAKE8ADDR     BIT(4)
  35 /* Factory-programmed serial number. */
  36 #define AT24_FLAG_SERIAL        BIT(3)
  37 /* Factory-programmed mac address. */
  38 #define AT24_FLAG_MAC           BIT(2)
  39 /* Does not auto-rollover reads to the next slave address. */
  40 #define AT24_FLAG_NO_RDROL      BIT(1)
  41 
  42 /*
  43  * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
  44  * Differences between different vendor product lines (like Atmel AT24C or
  45  * MicroChip 24LC, etc) won't much matter for typical read/write access.
  46  * There are also I2C RAM chips, likewise interchangeable. One example
  47  * would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
  48  *
  49  * However, misconfiguration can lose data. "Set 16-bit memory address"
  50  * to a part with 8-bit addressing will overwrite data. Writing with too
  51  * big a page size also loses data. And it's not safe to assume that the
  52  * conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
  53  * uses 0x51, for just one example.
  54  *
  55  * Accordingly, explicit board-specific configuration data should be used
  56  * in almost all cases. (One partial exception is an SMBus used to access
  57  * "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
  58  *
  59  * So this driver uses "new style" I2C driver binding, expecting to be
  60  * told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
  61  * similar kernel-resident tables; or, configuration data coming from
  62  * a bootloader.
  63  *
  64  * Other than binding model, current differences from "eeprom" driver are
  65  * that this one handles write access and isn't restricted to 24c02 devices.
  66  * It also handles larger devices (32 kbit and up) with two-byte addresses,
  67  * which won't work on pure SMBus systems.
  68  */
  69 
  70 struct at24_client {
  71         struct i2c_client *client;
  72         struct regmap *regmap;
  73 };
  74 
  75 struct at24_data {
  76         /*
  77          * Lock protects against activities from other Linux tasks,
  78          * but not from changes by other I2C masters.
  79          */
  80         struct mutex lock;
  81 
  82         unsigned int write_max;
  83         unsigned int num_addresses;
  84         unsigned int offset_adj;
  85 
  86         u32 byte_len;
  87         u16 page_size;
  88         u8 flags;
  89 
  90         struct nvmem_device *nvmem;
  91 
  92         struct gpio_desc *wp_gpio;
  93 
  94         /*
  95          * Some chips tie up multiple I2C addresses; dummy devices reserve
  96          * them for us, and we'll use them with SMBus calls.
  97          */
  98         struct at24_client client[];
  99 };
 100 
 101 /*
 102  * This parameter is to help this driver avoid blocking other drivers out
 103  * of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
 104  * clock, one 256 byte read takes about 1/43 second which is excessive;
 105  * but the 1/170 second it takes at 400 kHz may be quite reasonable; and
 106  * at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
 107  *
 108  * This value is forced to be a power of two so that writes align on pages.
 109  */
 110 static unsigned int at24_io_limit = 128;
 111 module_param_named(io_limit, at24_io_limit, uint, 0);
 112 MODULE_PARM_DESC(at24_io_limit, "Maximum bytes per I/O (default 128)");
 113 
 114 /*
 115  * Specs often allow 5 msec for a page write, sometimes 20 msec;
 116  * it's important to recover from write timeouts.
 117  */
 118 static unsigned int at24_write_timeout = 25;
 119 module_param_named(write_timeout, at24_write_timeout, uint, 0);
 120 MODULE_PARM_DESC(at24_write_timeout, "Time (in ms) to try writes (default 25)");
 121 
 122 struct at24_chip_data {
 123         u32 byte_len;
 124         u8 flags;
 125 };
 126 
 127 #define AT24_CHIP_DATA(_name, _len, _flags)                             \
 128         static const struct at24_chip_data _name = {                    \
 129                 .byte_len = _len, .flags = _flags,                      \
 130         }
 131 
 132 /* needs 8 addresses as A0-A2 are ignored */
 133 AT24_CHIP_DATA(at24_data_24c00, 128 / 8, AT24_FLAG_TAKE8ADDR);
 134 /* old variants can't be handled with this generic entry! */
 135 AT24_CHIP_DATA(at24_data_24c01, 1024 / 8, 0);
 136 AT24_CHIP_DATA(at24_data_24cs01, 16,
 137         AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
 138 AT24_CHIP_DATA(at24_data_24c02, 2048 / 8, 0);
 139 AT24_CHIP_DATA(at24_data_24cs02, 16,
 140         AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
 141 AT24_CHIP_DATA(at24_data_24mac402, 48 / 8,
 142         AT24_FLAG_MAC | AT24_FLAG_READONLY);
 143 AT24_CHIP_DATA(at24_data_24mac602, 64 / 8,
 144         AT24_FLAG_MAC | AT24_FLAG_READONLY);
 145 /* spd is a 24c02 in memory DIMMs */
 146 AT24_CHIP_DATA(at24_data_spd, 2048 / 8,
 147         AT24_FLAG_READONLY | AT24_FLAG_IRUGO);
 148 AT24_CHIP_DATA(at24_data_24c04, 4096 / 8, 0);
 149 AT24_CHIP_DATA(at24_data_24cs04, 16,
 150         AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
 151 /* 24rf08 quirk is handled at i2c-core */
 152 AT24_CHIP_DATA(at24_data_24c08, 8192 / 8, 0);
 153 AT24_CHIP_DATA(at24_data_24cs08, 16,
 154         AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
 155 AT24_CHIP_DATA(at24_data_24c16, 16384 / 8, 0);
 156 AT24_CHIP_DATA(at24_data_24cs16, 16,
 157         AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
 158 AT24_CHIP_DATA(at24_data_24c32, 32768 / 8, AT24_FLAG_ADDR16);
 159 AT24_CHIP_DATA(at24_data_24cs32, 16,
 160         AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
 161 AT24_CHIP_DATA(at24_data_24c64, 65536 / 8, AT24_FLAG_ADDR16);
 162 AT24_CHIP_DATA(at24_data_24cs64, 16,
 163         AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
 164 AT24_CHIP_DATA(at24_data_24c128, 131072 / 8, AT24_FLAG_ADDR16);
 165 AT24_CHIP_DATA(at24_data_24c256, 262144 / 8, AT24_FLAG_ADDR16);
 166 AT24_CHIP_DATA(at24_data_24c512, 524288 / 8, AT24_FLAG_ADDR16);
 167 AT24_CHIP_DATA(at24_data_24c1024, 1048576 / 8, AT24_FLAG_ADDR16);
 168 AT24_CHIP_DATA(at24_data_24c2048, 2097152 / 8, AT24_FLAG_ADDR16);
 169 /* identical to 24c08 ? */
 170 AT24_CHIP_DATA(at24_data_INT3499, 8192 / 8, 0);
 171 
 172 static const struct i2c_device_id at24_ids[] = {
 173         { "24c00",      (kernel_ulong_t)&at24_data_24c00 },
 174         { "24c01",      (kernel_ulong_t)&at24_data_24c01 },
 175         { "24cs01",     (kernel_ulong_t)&at24_data_24cs01 },
 176         { "24c02",      (kernel_ulong_t)&at24_data_24c02 },
 177         { "24cs02",     (kernel_ulong_t)&at24_data_24cs02 },
 178         { "24mac402",   (kernel_ulong_t)&at24_data_24mac402 },
 179         { "24mac602",   (kernel_ulong_t)&at24_data_24mac602 },
 180         { "spd",        (kernel_ulong_t)&at24_data_spd },
 181         { "24c04",      (kernel_ulong_t)&at24_data_24c04 },
 182         { "24cs04",     (kernel_ulong_t)&at24_data_24cs04 },
 183         { "24c08",      (kernel_ulong_t)&at24_data_24c08 },
 184         { "24cs08",     (kernel_ulong_t)&at24_data_24cs08 },
 185         { "24c16",      (kernel_ulong_t)&at24_data_24c16 },
 186         { "24cs16",     (kernel_ulong_t)&at24_data_24cs16 },
 187         { "24c32",      (kernel_ulong_t)&at24_data_24c32 },
 188         { "24cs32",     (kernel_ulong_t)&at24_data_24cs32 },
 189         { "24c64",      (kernel_ulong_t)&at24_data_24c64 },
 190         { "24cs64",     (kernel_ulong_t)&at24_data_24cs64 },
 191         { "24c128",     (kernel_ulong_t)&at24_data_24c128 },
 192         { "24c256",     (kernel_ulong_t)&at24_data_24c256 },
 193         { "24c512",     (kernel_ulong_t)&at24_data_24c512 },
 194         { "24c1024",    (kernel_ulong_t)&at24_data_24c1024 },
 195         { "24c2048",    (kernel_ulong_t)&at24_data_24c2048 },
 196         { "at24",       0 },
 197         { /* END OF LIST */ }
 198 };
 199 MODULE_DEVICE_TABLE(i2c, at24_ids);
 200 
 201 static const struct of_device_id at24_of_match[] = {
 202         { .compatible = "atmel,24c00",          .data = &at24_data_24c00 },
 203         { .compatible = "atmel,24c01",          .data = &at24_data_24c01 },
 204         { .compatible = "atmel,24cs01",         .data = &at24_data_24cs01 },
 205         { .compatible = "atmel,24c02",          .data = &at24_data_24c02 },
 206         { .compatible = "atmel,24cs02",         .data = &at24_data_24cs02 },
 207         { .compatible = "atmel,24mac402",       .data = &at24_data_24mac402 },
 208         { .compatible = "atmel,24mac602",       .data = &at24_data_24mac602 },
 209         { .compatible = "atmel,spd",            .data = &at24_data_spd },
 210         { .compatible = "atmel,24c04",          .data = &at24_data_24c04 },
 211         { .compatible = "atmel,24cs04",         .data = &at24_data_24cs04 },
 212         { .compatible = "atmel,24c08",          .data = &at24_data_24c08 },
 213         { .compatible = "atmel,24cs08",         .data = &at24_data_24cs08 },
 214         { .compatible = "atmel,24c16",          .data = &at24_data_24c16 },
 215         { .compatible = "atmel,24cs16",         .data = &at24_data_24cs16 },
 216         { .compatible = "atmel,24c32",          .data = &at24_data_24c32 },
 217         { .compatible = "atmel,24cs32",         .data = &at24_data_24cs32 },
 218         { .compatible = "atmel,24c64",          .data = &at24_data_24c64 },
 219         { .compatible = "atmel,24cs64",         .data = &at24_data_24cs64 },
 220         { .compatible = "atmel,24c128",         .data = &at24_data_24c128 },
 221         { .compatible = "atmel,24c256",         .data = &at24_data_24c256 },
 222         { .compatible = "atmel,24c512",         .data = &at24_data_24c512 },
 223         { .compatible = "atmel,24c1024",        .data = &at24_data_24c1024 },
 224         { .compatible = "atmel,24c2048",        .data = &at24_data_24c2048 },
 225         { /* END OF LIST */ },
 226 };
 227 MODULE_DEVICE_TABLE(of, at24_of_match);
 228 
 229 static const struct acpi_device_id at24_acpi_ids[] = {
 230         { "INT3499",    (kernel_ulong_t)&at24_data_INT3499 },
 231         { /* END OF LIST */ }
 232 };
 233 MODULE_DEVICE_TABLE(acpi, at24_acpi_ids);
 234 
 235 /*
 236  * This routine supports chips which consume multiple I2C addresses. It
 237  * computes the addressing information to be used for a given r/w request.
 238  * Assumes that sanity checks for offset happened at sysfs-layer.
 239  *
 240  * Slave address and byte offset derive from the offset. Always
 241  * set the byte address; on a multi-master board, another master
 242  * may have changed the chip's "current" address pointer.
 243  */
 244 static struct at24_client *at24_translate_offset(struct at24_data *at24,
 245                                                  unsigned int *offset)
 246 {
 247         unsigned int i;
 248 
 249         if (at24->flags & AT24_FLAG_ADDR16) {
 250                 i = *offset >> 16;
 251                 *offset &= 0xffff;
 252         } else {
 253                 i = *offset >> 8;
 254                 *offset &= 0xff;
 255         }
 256 
 257         return &at24->client[i];
 258 }
 259 
 260 static struct device *at24_base_client_dev(struct at24_data *at24)
 261 {
 262         return &at24->client[0].client->dev;
 263 }
 264 
 265 static size_t at24_adjust_read_count(struct at24_data *at24,
 266                                       unsigned int offset, size_t count)
 267 {
 268         unsigned int bits;
 269         size_t remainder;
 270 
 271         /*
 272          * In case of multi-address chips that don't rollover reads to
 273          * the next slave address: truncate the count to the slave boundary,
 274          * so that the read never straddles slaves.
 275          */
 276         if (at24->flags & AT24_FLAG_NO_RDROL) {
 277                 bits = (at24->flags & AT24_FLAG_ADDR16) ? 16 : 8;
 278                 remainder = BIT(bits) - offset;
 279                 if (count > remainder)
 280                         count = remainder;
 281         }
 282 
 283         if (count > at24_io_limit)
 284                 count = at24_io_limit;
 285 
 286         return count;
 287 }
 288 
 289 static ssize_t at24_regmap_read(struct at24_data *at24, char *buf,
 290                                 unsigned int offset, size_t count)
 291 {
 292         unsigned long timeout, read_time;
 293         struct at24_client *at24_client;
 294         struct i2c_client *client;
 295         struct regmap *regmap;
 296         int ret;
 297 
 298         at24_client = at24_translate_offset(at24, &offset);
 299         regmap = at24_client->regmap;
 300         client = at24_client->client;
 301         count = at24_adjust_read_count(at24, offset, count);
 302 
 303         /* adjust offset for mac and serial read ops */
 304         offset += at24->offset_adj;
 305 
 306         timeout = jiffies + msecs_to_jiffies(at24_write_timeout);
 307         do {
 308                 /*
 309                  * The timestamp shall be taken before the actual operation
 310                  * to avoid a premature timeout in case of high CPU load.
 311                  */
 312                 read_time = jiffies;
 313 
 314                 ret = regmap_bulk_read(regmap, offset, buf, count);
 315                 dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
 316                         count, offset, ret, jiffies);
 317                 if (!ret)
 318                         return count;
 319 
 320                 usleep_range(1000, 1500);
 321         } while (time_before(read_time, timeout));
 322 
 323         return -ETIMEDOUT;
 324 }
 325 
 326 /*
 327  * Note that if the hardware write-protect pin is pulled high, the whole
 328  * chip is normally write protected. But there are plenty of product
 329  * variants here, including OTP fuses and partial chip protect.
 330  *
 331  * We only use page mode writes; the alternative is sloooow. These routines
 332  * write at most one page.
 333  */
 334 
 335 static size_t at24_adjust_write_count(struct at24_data *at24,
 336                                       unsigned int offset, size_t count)
 337 {
 338         unsigned int next_page;
 339 
 340         /* write_max is at most a page */
 341         if (count > at24->write_max)
 342                 count = at24->write_max;
 343 
 344         /* Never roll over backwards, to the start of this page */
 345         next_page = roundup(offset + 1, at24->page_size);
 346         if (offset + count > next_page)
 347                 count = next_page - offset;
 348 
 349         return count;
 350 }
 351 
 352 static ssize_t at24_regmap_write(struct at24_data *at24, const char *buf,
 353                                  unsigned int offset, size_t count)
 354 {
 355         unsigned long timeout, write_time;
 356         struct at24_client *at24_client;
 357         struct i2c_client *client;
 358         struct regmap *regmap;
 359         int ret;
 360 
 361         at24_client = at24_translate_offset(at24, &offset);
 362         regmap = at24_client->regmap;
 363         client = at24_client->client;
 364         count = at24_adjust_write_count(at24, offset, count);
 365         timeout = jiffies + msecs_to_jiffies(at24_write_timeout);
 366 
 367         do {
 368                 /*
 369                  * The timestamp shall be taken before the actual operation
 370                  * to avoid a premature timeout in case of high CPU load.
 371                  */
 372                 write_time = jiffies;
 373 
 374                 ret = regmap_bulk_write(regmap, offset, buf, count);
 375                 dev_dbg(&client->dev, "write %zu@%d --> %d (%ld)\n",
 376                         count, offset, ret, jiffies);
 377                 if (!ret)
 378                         return count;
 379 
 380                 usleep_range(1000, 1500);
 381         } while (time_before(write_time, timeout));
 382 
 383         return -ETIMEDOUT;
 384 }
 385 
 386 static int at24_read(void *priv, unsigned int off, void *val, size_t count)
 387 {
 388         struct at24_data *at24;
 389         struct device *dev;
 390         char *buf = val;
 391         int ret;
 392 
 393         at24 = priv;
 394         dev = at24_base_client_dev(at24);
 395 
 396         if (unlikely(!count))
 397                 return count;
 398 
 399         if (off + count > at24->byte_len)
 400                 return -EINVAL;
 401 
 402         ret = pm_runtime_get_sync(dev);
 403         if (ret < 0) {
 404                 pm_runtime_put_noidle(dev);
 405                 return ret;
 406         }
 407 
 408         /*
 409          * Read data from chip, protecting against concurrent updates
 410          * from this host, but not from other I2C masters.
 411          */
 412         mutex_lock(&at24->lock);
 413 
 414         while (count) {
 415                 ret = at24_regmap_read(at24, buf, off, count);
 416                 if (ret < 0) {
 417                         mutex_unlock(&at24->lock);
 418                         pm_runtime_put(dev);
 419                         return ret;
 420                 }
 421                 buf += ret;
 422                 off += ret;
 423                 count -= ret;
 424         }
 425 
 426         mutex_unlock(&at24->lock);
 427 
 428         pm_runtime_put(dev);
 429 
 430         return 0;
 431 }
 432 
 433 static int at24_write(void *priv, unsigned int off, void *val, size_t count)
 434 {
 435         struct at24_data *at24;
 436         struct device *dev;
 437         char *buf = val;
 438         int ret;
 439 
 440         at24 = priv;
 441         dev = at24_base_client_dev(at24);
 442 
 443         if (unlikely(!count))
 444                 return -EINVAL;
 445 
 446         if (off + count > at24->byte_len)
 447                 return -EINVAL;
 448 
 449         ret = pm_runtime_get_sync(dev);
 450         if (ret < 0) {
 451                 pm_runtime_put_noidle(dev);
 452                 return ret;
 453         }
 454 
 455         /*
 456          * Write data to chip, protecting against concurrent updates
 457          * from this host, but not from other I2C masters.
 458          */
 459         mutex_lock(&at24->lock);
 460         gpiod_set_value_cansleep(at24->wp_gpio, 0);
 461 
 462         while (count) {
 463                 ret = at24_regmap_write(at24, buf, off, count);
 464                 if (ret < 0) {
 465                         gpiod_set_value_cansleep(at24->wp_gpio, 1);
 466                         mutex_unlock(&at24->lock);
 467                         pm_runtime_put(dev);
 468                         return ret;
 469                 }
 470                 buf += ret;
 471                 off += ret;
 472                 count -= ret;
 473         }
 474 
 475         gpiod_set_value_cansleep(at24->wp_gpio, 1);
 476         mutex_unlock(&at24->lock);
 477 
 478         pm_runtime_put(dev);
 479 
 480         return 0;
 481 }
 482 
 483 static const struct at24_chip_data *at24_get_chip_data(struct device *dev)
 484 {
 485         struct device_node *of_node = dev->of_node;
 486         const struct at24_chip_data *cdata;
 487         const struct i2c_device_id *id;
 488 
 489         id = i2c_match_id(at24_ids, to_i2c_client(dev));
 490 
 491         /*
 492          * The I2C core allows OF nodes compatibles to match against the
 493          * I2C device ID table as a fallback, so check not only if an OF
 494          * node is present but also if it matches an OF device ID entry.
 495          */
 496         if (of_node && of_match_device(at24_of_match, dev))
 497                 cdata = of_device_get_match_data(dev);
 498         else if (id)
 499                 cdata = (void *)id->driver_data;
 500         else
 501                 cdata = acpi_device_get_match_data(dev);
 502 
 503         if (!cdata)
 504                 return ERR_PTR(-ENODEV);
 505 
 506         return cdata;
 507 }
 508 
 509 static int at24_make_dummy_client(struct at24_data *at24, unsigned int index,
 510                                   struct regmap_config *regmap_config)
 511 {
 512         struct i2c_client *base_client, *dummy_client;
 513         struct regmap *regmap;
 514         struct device *dev;
 515 
 516         base_client = at24->client[0].client;
 517         dev = &base_client->dev;
 518 
 519         dummy_client = devm_i2c_new_dummy_device(dev, base_client->adapter,
 520                                                  base_client->addr + index);
 521         if (IS_ERR(dummy_client))
 522                 return PTR_ERR(dummy_client);
 523 
 524         regmap = devm_regmap_init_i2c(dummy_client, regmap_config);
 525         if (IS_ERR(regmap))
 526                 return PTR_ERR(regmap);
 527 
 528         at24->client[index].client = dummy_client;
 529         at24->client[index].regmap = regmap;
 530 
 531         return 0;
 532 }
 533 
 534 static unsigned int at24_get_offset_adj(u8 flags, unsigned int byte_len)
 535 {
 536         if (flags & AT24_FLAG_MAC) {
 537                 /* EUI-48 starts from 0x9a, EUI-64 from 0x98 */
 538                 return 0xa0 - byte_len;
 539         } else if (flags & AT24_FLAG_SERIAL && flags & AT24_FLAG_ADDR16) {
 540                 /*
 541                  * For 16 bit address pointers, the word address must contain
 542                  * a '10' sequence in bits 11 and 10 regardless of the
 543                  * intended position of the address pointer.
 544                  */
 545                 return 0x0800;
 546         } else if (flags & AT24_FLAG_SERIAL) {
 547                 /*
 548                  * Otherwise the word address must begin with a '10' sequence,
 549                  * regardless of the intended address.
 550                  */
 551                 return 0x0080;
 552         } else {
 553                 return 0;
 554         }
 555 }
 556 
 557 static int at24_probe(struct i2c_client *client)
 558 {
 559         struct regmap_config regmap_config = { };
 560         struct nvmem_config nvmem_config = { };
 561         u32 byte_len, page_size, flags, addrw;
 562         const struct at24_chip_data *cdata;
 563         struct device *dev = &client->dev;
 564         bool i2c_fn_i2c, i2c_fn_block;
 565         unsigned int i, num_addresses;
 566         struct at24_data *at24;
 567         struct regmap *regmap;
 568         bool writable;
 569         u8 test_byte;
 570         int err;
 571 
 572         i2c_fn_i2c = i2c_check_functionality(client->adapter, I2C_FUNC_I2C);
 573         i2c_fn_block = i2c_check_functionality(client->adapter,
 574                                                I2C_FUNC_SMBUS_WRITE_I2C_BLOCK);
 575 
 576         cdata = at24_get_chip_data(dev);
 577         if (IS_ERR(cdata))
 578                 return PTR_ERR(cdata);
 579 
 580         err = device_property_read_u32(dev, "pagesize", &page_size);
 581         if (err)
 582                 /*
 583                  * This is slow, but we can't know all eeproms, so we better
 584                  * play safe. Specifying custom eeprom-types via device tree
 585                  * or properties is recommended anyhow.
 586                  */
 587                 page_size = 1;
 588 
 589         flags = cdata->flags;
 590         if (device_property_present(dev, "read-only"))
 591                 flags |= AT24_FLAG_READONLY;
 592         if (device_property_present(dev, "no-read-rollover"))
 593                 flags |= AT24_FLAG_NO_RDROL;
 594 
 595         err = device_property_read_u32(dev, "address-width", &addrw);
 596         if (!err) {
 597                 switch (addrw) {
 598                 case 8:
 599                         if (flags & AT24_FLAG_ADDR16)
 600                                 dev_warn(dev,
 601                                          "Override address width to be 8, while default is 16\n");
 602                         flags &= ~AT24_FLAG_ADDR16;
 603                         break;
 604                 case 16:
 605                         flags |= AT24_FLAG_ADDR16;
 606                         break;
 607                 default:
 608                         dev_warn(dev, "Bad \"address-width\" property: %u\n",
 609                                  addrw);
 610                 }
 611         }
 612 
 613         err = device_property_read_u32(dev, "size", &byte_len);
 614         if (err)
 615                 byte_len = cdata->byte_len;
 616 
 617         if (!i2c_fn_i2c && !i2c_fn_block)
 618                 page_size = 1;
 619 
 620         if (!page_size) {
 621                 dev_err(dev, "page_size must not be 0!\n");
 622                 return -EINVAL;
 623         }
 624 
 625         if (!is_power_of_2(page_size))
 626                 dev_warn(dev, "page_size looks suspicious (no power of 2)!\n");
 627 
 628         err = device_property_read_u32(dev, "num-addresses", &num_addresses);
 629         if (err) {
 630                 if (flags & AT24_FLAG_TAKE8ADDR)
 631                         num_addresses = 8;
 632                 else
 633                         num_addresses = DIV_ROUND_UP(byte_len,
 634                                 (flags & AT24_FLAG_ADDR16) ? 65536 : 256);
 635         }
 636 
 637         if ((flags & AT24_FLAG_SERIAL) && (flags & AT24_FLAG_MAC)) {
 638                 dev_err(dev,
 639                         "invalid device data - cannot have both AT24_FLAG_SERIAL & AT24_FLAG_MAC.");
 640                 return -EINVAL;
 641         }
 642 
 643         regmap_config.val_bits = 8;
 644         regmap_config.reg_bits = (flags & AT24_FLAG_ADDR16) ? 16 : 8;
 645         regmap_config.disable_locking = true;
 646 
 647         regmap = devm_regmap_init_i2c(client, &regmap_config);
 648         if (IS_ERR(regmap))
 649                 return PTR_ERR(regmap);
 650 
 651         at24 = devm_kzalloc(dev, struct_size(at24, client, num_addresses),
 652                             GFP_KERNEL);
 653         if (!at24)
 654                 return -ENOMEM;
 655 
 656         mutex_init(&at24->lock);
 657         at24->byte_len = byte_len;
 658         at24->page_size = page_size;
 659         at24->flags = flags;
 660         at24->num_addresses = num_addresses;
 661         at24->offset_adj = at24_get_offset_adj(flags, byte_len);
 662         at24->client[0].client = client;
 663         at24->client[0].regmap = regmap;
 664 
 665         at24->wp_gpio = devm_gpiod_get_optional(dev, "wp", GPIOD_OUT_HIGH);
 666         if (IS_ERR(at24->wp_gpio))
 667                 return PTR_ERR(at24->wp_gpio);
 668 
 669         writable = !(flags & AT24_FLAG_READONLY);
 670         if (writable) {
 671                 at24->write_max = min_t(unsigned int,
 672                                         page_size, at24_io_limit);
 673                 if (!i2c_fn_i2c && at24->write_max > I2C_SMBUS_BLOCK_MAX)
 674                         at24->write_max = I2C_SMBUS_BLOCK_MAX;
 675         }
 676 
 677         /* use dummy devices for multiple-address chips */
 678         for (i = 1; i < num_addresses; i++) {
 679                 err = at24_make_dummy_client(at24, i, &regmap_config);
 680                 if (err)
 681                         return err;
 682         }
 683 
 684         nvmem_config.name = dev_name(dev);
 685         nvmem_config.dev = dev;
 686         nvmem_config.read_only = !writable;
 687         nvmem_config.root_only = !(flags & AT24_FLAG_IRUGO);
 688         nvmem_config.owner = THIS_MODULE;
 689         nvmem_config.compat = true;
 690         nvmem_config.base_dev = dev;
 691         nvmem_config.reg_read = at24_read;
 692         nvmem_config.reg_write = at24_write;
 693         nvmem_config.priv = at24;
 694         nvmem_config.stride = 1;
 695         nvmem_config.word_size = 1;
 696         nvmem_config.size = byte_len;
 697 
 698         at24->nvmem = devm_nvmem_register(dev, &nvmem_config);
 699         if (IS_ERR(at24->nvmem))
 700                 return PTR_ERR(at24->nvmem);
 701 
 702         i2c_set_clientdata(client, at24);
 703 
 704         /* enable runtime pm */
 705         pm_runtime_set_active(dev);
 706         pm_runtime_enable(dev);
 707 
 708         /*
 709          * Perform a one-byte test read to verify that the
 710          * chip is functional.
 711          */
 712         err = at24_read(at24, 0, &test_byte, 1);
 713         pm_runtime_idle(dev);
 714         if (err) {
 715                 pm_runtime_disable(dev);
 716                 return -ENODEV;
 717         }
 718 
 719         dev_info(dev, "%u byte %s EEPROM, %s, %u bytes/write\n",
 720                  byte_len, client->name,
 721                  writable ? "writable" : "read-only", at24->write_max);
 722 
 723         return 0;
 724 }
 725 
 726 static int at24_remove(struct i2c_client *client)
 727 {
 728         pm_runtime_disable(&client->dev);
 729         pm_runtime_set_suspended(&client->dev);
 730 
 731         return 0;
 732 }
 733 
 734 static struct i2c_driver at24_driver = {
 735         .driver = {
 736                 .name = "at24",
 737                 .of_match_table = at24_of_match,
 738                 .acpi_match_table = ACPI_PTR(at24_acpi_ids),
 739         },
 740         .probe_new = at24_probe,
 741         .remove = at24_remove,
 742         .id_table = at24_ids,
 743 };
 744 
 745 static int __init at24_init(void)
 746 {
 747         if (!at24_io_limit) {
 748                 pr_err("at24: at24_io_limit must not be 0!\n");
 749                 return -EINVAL;
 750         }
 751 
 752         at24_io_limit = rounddown_pow_of_two(at24_io_limit);
 753         return i2c_add_driver(&at24_driver);
 754 }
 755 module_init(at24_init);
 756 
 757 static void __exit at24_exit(void)
 758 {
 759         i2c_del_driver(&at24_driver);
 760 }
 761 module_exit(at24_exit);
 762 
 763 MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
 764 MODULE_AUTHOR("David Brownell and Wolfram Sang");
 765 MODULE_LICENSE("GPL");
/* [<][>][^][v][top][bottom][index][help] */
root/drivers/misc/eeprom/at24.c

DEFINITIONS
