drivers/misc/eeprom/eeprom_93xx46.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Driver for 93xx46 EEPROMs
   4  *
   5  * (C) 2011 DENX Software Engineering, Anatolij Gustschin <[email protected]>
   6  */
   7
   8 #include <linux/delay.h>
   9 #include <linux/device.h>
  10 #include <linux/gpio/consumer.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/mutex.h>
  14 #include <linux/of.h>
  15 #include <linux/of_device.h>
  16 #include <linux/of_gpio.h>
  17 #include <linux/slab.h>
  18 #include <linux/spi/spi.h>
  19 #include <linux/nvmem-provider.h>
  20 #include <linux/eeprom_93xx46.h>
  21
  22 #define OP_START        0x4
  23 #define OP_WRITE        (OP_START | 0x1)
  24 #define OP_READ         (OP_START | 0x2)
  25 #define ADDR_EWDS       0x00
  26 #define ADDR_ERAL       0x20
  27 #define ADDR_EWEN       0x30
  28
  29 struct eeprom_93xx46_devtype_data {
  30         unsigned int quirks;
  31 };
  32
  33 static const struct eeprom_93xx46_devtype_data atmel_at93c46d_data = {
  34         .quirks = EEPROM_93XX46_QUIRK_SINGLE_WORD_READ |
  35                   EEPROM_93XX46_QUIRK_INSTRUCTION_LENGTH,
  36 };
  37
  38 struct eeprom_93xx46_dev {
  39         struct spi_device *spi;
  40         struct eeprom_93xx46_platform_data *pdata;
  41         struct mutex lock;
  42         struct nvmem_config nvmem_config;
  43         struct nvmem_device *nvmem;
  44         int addrlen;
  45         int size;
  46 };
  47
  48 static inline bool has_quirk_single_word_read(struct eeprom_93xx46_dev *edev)
  49 {
  50         return edev->pdata->quirks & EEPROM_93XX46_QUIRK_SINGLE_WORD_READ;
  51 }
  52
  53 static inline bool has_quirk_instruction_length(struct eeprom_93xx46_dev *edev)
  54 {
  55         return edev->pdata->quirks & EEPROM_93XX46_QUIRK_INSTRUCTION_LENGTH;
  56 }
  57
  58 static int eeprom_93xx46_read(void *priv, unsigned int off,
  59                               void *val, size_t count)
  60 {
  61         struct eeprom_93xx46_dev *edev = priv;
  62         char *buf = val;
  63         int err = 0;
  64
  65         if (unlikely(off >= edev->size))
  66                 return 0;
  67         if ((off + count) > edev->size)
  68                 count = edev->size - off;
  69         if (unlikely(!count))
  70                 return count;
  71
  72         mutex_lock(&edev->lock);
  73
  74         if (edev->pdata->prepare)
  75                 edev->pdata->prepare(edev);
  76
  77         while (count) {
  78                 struct spi_message m;
  79                 struct spi_transfer t[2] = { { 0 } };
  80                 u16 cmd_addr = OP_READ << edev->addrlen;
  81                 size_t nbytes = count;
  82                 int bits;
  83
  84                 if (edev->addrlen == 7) {
  85                         cmd_addr |= off & 0x7f;
  86                         bits = 10;
  87                         if (has_quirk_single_word_read(edev))
  88                                 nbytes = 1;
  89                 } else {
  90                         cmd_addr |= (off >> 1) & 0x3f;
  91                         bits = 9;
  92                         if (has_quirk_single_word_read(edev))
  93                                 nbytes = 2;
  94                 }
  95
  96                 dev_dbg(&edev->spi->dev, "read cmd 0x%x, %d Hz\n",
  97                         cmd_addr, edev->spi->max_speed_hz);
  98
  99                 spi_message_init(&m);
 100
 101                 t[0].tx_buf = (char *)&cmd_addr;
 102                 t[0].len = 2;
 103                 t[0].bits_per_word = bits;
 104                 spi_message_add_tail(&t[0], &m);
 105
 106                 t[1].rx_buf = buf;
 107                 t[1].len = count;
 108                 t[1].bits_per_word = 8;
 109                 spi_message_add_tail(&t[1], &m);
 110
 111                 err = spi_sync(edev->spi, &m);
 112                 /* have to wait at least Tcsl ns */
 113                 ndelay(250);
 114
 115                 if (err) {
 116                         dev_err(&edev->spi->dev, "read %zu bytes at %d: err. %d\n",
 117                                 nbytes, (int)off, err);
 118                         break;
 119                 }
 120
 121                 buf += nbytes;
 122                 off += nbytes;
 123                 count -= nbytes;
 124         }
 125
 126         if (edev->pdata->finish)
 127                 edev->pdata->finish(edev);
 128
 129         mutex_unlock(&edev->lock);
 130
 131         return err;
 132 }
 133
 134 static int eeprom_93xx46_ew(struct eeprom_93xx46_dev *edev, int is_on)
 135 {
 136         struct spi_message m;
 137         struct spi_transfer t;
 138         int bits, ret;
 139         u16 cmd_addr;
 140
 141         cmd_addr = OP_START << edev->addrlen;
 142         if (edev->addrlen == 7) {
 143                 cmd_addr |= (is_on ? ADDR_EWEN : ADDR_EWDS) << 1;
 144                 bits = 10;
 145         } else {
 146                 cmd_addr |= (is_on ? ADDR_EWEN : ADDR_EWDS);
 147                 bits = 9;
 148         }
 149
 150         if (has_quirk_instruction_length(edev)) {
 151                 cmd_addr <<= 2;
 152                 bits += 2;
 153         }
 154
 155         dev_dbg(&edev->spi->dev, "ew%s cmd 0x%04x, %d bits\n",
 156                         is_on ? "en" : "ds", cmd_addr, bits);
 157
 158         spi_message_init(&m);
 159         memset(&t, 0, sizeof(t));
 160
 161         t.tx_buf = &cmd_addr;
 162         t.len = 2;
 163         t.bits_per_word = bits;
 164         spi_message_add_tail(&t, &m);
 165
 166         mutex_lock(&edev->lock);
 167
 168         if (edev->pdata->prepare)
 169                 edev->pdata->prepare(edev);
 170
 171         ret = spi_sync(edev->spi, &m);
 172         /* have to wait at least Tcsl ns */
 173         ndelay(250);
 174         if (ret)
 175                 dev_err(&edev->spi->dev, "erase/write %sable error %d\n",
 176                         is_on ? "en" : "dis", ret);
 177
 178         if (edev->pdata->finish)
 179                 edev->pdata->finish(edev);
 180
 181         mutex_unlock(&edev->lock);
 182         return ret;
 183 }
 184
 185 static ssize_t
 186 eeprom_93xx46_write_word(struct eeprom_93xx46_dev *edev,
 187                          const char *buf, unsigned off)
 188 {
 189         struct spi_message m;
 190         struct spi_transfer t[2];
 191         int bits, data_len, ret;
 192         u16 cmd_addr;
 193
 194         cmd_addr = OP_WRITE << edev->addrlen;
 195
 196         if (edev->addrlen == 7) {
 197                 cmd_addr |= off & 0x7f;
 198                 bits = 10;
 199                 data_len = 1;
 200         } else {
 201                 cmd_addr |= (off >> 1) & 0x3f;
 202                 bits = 9;
 203                 data_len = 2;
 204         }
 205
 206         dev_dbg(&edev->spi->dev, "write cmd 0x%x\n", cmd_addr);
 207
 208         spi_message_init(&m);
 209         memset(t, 0, sizeof(t));
 210
 211         t[0].tx_buf = (char *)&cmd_addr;
 212         t[0].len = 2;
 213         t[0].bits_per_word = bits;
 214         spi_message_add_tail(&t[0], &m);
 215
 216         t[1].tx_buf = buf;
 217         t[1].len = data_len;
 218         t[1].bits_per_word = 8;
 219         spi_message_add_tail(&t[1], &m);
 220
 221         ret = spi_sync(edev->spi, &m);
 222         /* have to wait program cycle time Twc ms */
 223         mdelay(6);
 224         return ret;
 225 }
 226
 227 static int eeprom_93xx46_write(void *priv, unsigned int off,
 228                                    void *val, size_t count)
 229 {
 230         struct eeprom_93xx46_dev *edev = priv;
 231         char *buf = val;
 232         int i, ret, step = 1;
 233
 234         if (unlikely(off >= edev->size))
 235                 return -EFBIG;
 236         if ((off + count) > edev->size)
 237                 count = edev->size - off;
 238         if (unlikely(!count))
 239                 return count;
 240
 241         /* only write even number of bytes on 16-bit devices */
 242         if (edev->addrlen == 6) {
 243                 step = 2;
 244                 count &= ~1;
 245         }
 246
 247         /* erase/write enable */
 248         ret = eeprom_93xx46_ew(edev, 1);
 249         if (ret)
 250                 return ret;
 251
 252         mutex_lock(&edev->lock);
 253
 254         if (edev->pdata->prepare)
 255                 edev->pdata->prepare(edev);
 256
 257         for (i = 0; i < count; i += step) {
 258                 ret = eeprom_93xx46_write_word(edev, &buf[i], off + i);
 259                 if (ret) {
 260                         dev_err(&edev->spi->dev, "write failed at %d: %d\n",
 261                                 (int)off + i, ret);
 262                         break;
 263                 }
 264         }
 265
 266         if (edev->pdata->finish)
 267                 edev->pdata->finish(edev);
 268
 269         mutex_unlock(&edev->lock);
 270
 271         /* erase/write disable */
 272         eeprom_93xx46_ew(edev, 0);
 273         return ret;
 274 }
 275
 276 static int eeprom_93xx46_eral(struct eeprom_93xx46_dev *edev)
 277 {
 278         struct eeprom_93xx46_platform_data *pd = edev->pdata;
 279         struct spi_message m;
 280         struct spi_transfer t;
 281         int bits, ret;
 282         u16 cmd_addr;
 283
 284         cmd_addr = OP_START << edev->addrlen;
 285         if (edev->addrlen == 7) {
 286                 cmd_addr |= ADDR_ERAL << 1;
 287                 bits = 10;
 288         } else {
 289                 cmd_addr |= ADDR_ERAL;
 290                 bits = 9;
 291         }
 292
 293         if (has_quirk_instruction_length(edev)) {
 294                 cmd_addr <<= 2;
 295                 bits += 2;
 296         }
 297
 298         dev_dbg(&edev->spi->dev, "eral cmd 0x%04x, %d bits\n", cmd_addr, bits);
 299
 300         spi_message_init(&m);
 301         memset(&t, 0, sizeof(t));
 302
 303         t.tx_buf = &cmd_addr;
 304         t.len = 2;
 305         t.bits_per_word = bits;
 306         spi_message_add_tail(&t, &m);
 307
 308         mutex_lock(&edev->lock);
 309
 310         if (edev->pdata->prepare)
 311                 edev->pdata->prepare(edev);
 312
 313         ret = spi_sync(edev->spi, &m);
 314         if (ret)
 315                 dev_err(&edev->spi->dev, "erase error %d\n", ret);
 316         /* have to wait erase cycle time Tec ms */
 317         mdelay(6);
 318
 319         if (pd->finish)
 320                 pd->finish(edev);
 321
 322         mutex_unlock(&edev->lock);
 323         return ret;
 324 }
 325
 326 static ssize_t eeprom_93xx46_store_erase(struct device *dev,
 327                                          struct device_attribute *attr,
 328                                          const char *buf, size_t count)
 329 {
 330         struct eeprom_93xx46_dev *edev = dev_get_drvdata(dev);
 331         int erase = 0, ret;
 332
 333         sscanf(buf, "%d", &erase);
 334         if (erase) {
 335                 ret = eeprom_93xx46_ew(edev, 1);
 336                 if (ret)
 337                         return ret;
 338                 ret = eeprom_93xx46_eral(edev);
 339                 if (ret)
 340                         return ret;
 341                 ret = eeprom_93xx46_ew(edev, 0);
 342                 if (ret)
 343                         return ret;
 344         }
 345         return count;
 346 }
 347 static DEVICE_ATTR(erase, S_IWUSR, NULL, eeprom_93xx46_store_erase);
 348
 349 static void select_assert(void *context)
 350 {
 351         struct eeprom_93xx46_dev *edev = context;
 352
 353         gpiod_set_value_cansleep(edev->pdata->select, 1);
 354 }
 355
 356 static void select_deassert(void *context)
 357 {
 358         struct eeprom_93xx46_dev *edev = context;
 359
 360         gpiod_set_value_cansleep(edev->pdata->select, 0);
 361 }
 362
 363 static const struct of_device_id eeprom_93xx46_of_table[] = {
 364         { .compatible = "eeprom-93xx46", },
 365         { .compatible = "atmel,at93c46d", .data = &atmel_at93c46d_data, },
 366         {}
 367 };
 368 MODULE_DEVICE_TABLE(of, eeprom_93xx46_of_table);
 369
 370 static int eeprom_93xx46_probe_dt(struct spi_device *spi)
 371 {
 372         const struct of_device_id *of_id =
 373                 of_match_device(eeprom_93xx46_of_table, &spi->dev);
 374         struct device_node *np = spi->dev.of_node;
 375         struct eeprom_93xx46_platform_data *pd;
 376         u32 tmp;
 377         int ret;
 378
 379         pd = devm_kzalloc(&spi->dev, sizeof(*pd), GFP_KERNEL);
 380         if (!pd)
 381                 return -ENOMEM;
 382
 383         ret = of_property_read_u32(np, "data-size", &tmp);
 384         if (ret < 0) {
 385                 dev_err(&spi->dev, "data-size property not found\n");
 386                 return ret;
 387         }
 388
 389         if (tmp == 8) {
 390                 pd->flags |= EE_ADDR8;
 391         } else if (tmp == 16) {
 392                 pd->flags |= EE_ADDR16;
 393         } else {
 394                 dev_err(&spi->dev, "invalid data-size (%d)\n", tmp);
 395                 return -EINVAL;
 396         }
 397
 398         if (of_property_read_bool(np, "read-only"))
 399                 pd->flags |= EE_READONLY;
 400
 401         pd->select = devm_gpiod_get_optional(&spi->dev, "select",
 402                                              GPIOD_OUT_LOW);
 403         if (IS_ERR(pd->select))
 404                 return PTR_ERR(pd->select);
 405
 406         pd->prepare = select_assert;
 407         pd->finish = select_deassert;
 408         gpiod_direction_output(pd->select, 0);
 409
 410         if (of_id->data) {
 411                 const struct eeprom_93xx46_devtype_data *data = of_id->data;
 412
 413                 pd->quirks = data->quirks;
 414         }
 415
 416         spi->dev.platform_data = pd;
 417
 418         return 0;
 419 }
 420
 421 static int eeprom_93xx46_probe(struct spi_device *spi)
 422 {
 423         struct eeprom_93xx46_platform_data *pd;
 424         struct eeprom_93xx46_dev *edev;
 425         int err;
 426
 427         if (spi->dev.of_node) {
 428                 err = eeprom_93xx46_probe_dt(spi);
 429                 if (err < 0)
 430                         return err;
 431         }
 432
 433         pd = spi->dev.platform_data;
 434         if (!pd) {
 435                 dev_err(&spi->dev, "missing platform data\n");
 436                 return -ENODEV;
 437         }
 438
 439         edev = devm_kzalloc(&spi->dev, sizeof(*edev), GFP_KERNEL);
 440         if (!edev)
 441                 return -ENOMEM;
 442
 443         if (pd->flags & EE_ADDR8)
 444                 edev->addrlen = 7;
 445         else if (pd->flags & EE_ADDR16)
 446                 edev->addrlen = 6;
 447         else {
 448                 dev_err(&spi->dev, "unspecified address type\n");
 449                 return -EINVAL;
 450         }
 451
 452         mutex_init(&edev->lock);
 453
 454         edev->spi = spi;
 455         edev->pdata = pd;
 456
 457         edev->size = 128;
 458         edev->nvmem_config.name = dev_name(&spi->dev);
 459         edev->nvmem_config.dev = &spi->dev;
 460         edev->nvmem_config.read_only = pd->flags & EE_READONLY;
 461         edev->nvmem_config.root_only = true;
 462         edev->nvmem_config.owner = THIS_MODULE;
 463         edev->nvmem_config.compat = true;
 464         edev->nvmem_config.base_dev = &spi->dev;
 465         edev->nvmem_config.reg_read = eeprom_93xx46_read;
 466         edev->nvmem_config.reg_write = eeprom_93xx46_write;
 467         edev->nvmem_config.priv = edev;
 468         edev->nvmem_config.stride = 4;
 469         edev->nvmem_config.word_size = 1;
 470         edev->nvmem_config.size = edev->size;
 471
 472         edev->nvmem = devm_nvmem_register(&spi->dev, &edev->nvmem_config);
 473         if (IS_ERR(edev->nvmem))
 474                 return PTR_ERR(edev->nvmem);
 475
 476         dev_info(&spi->dev, "%d-bit eeprom %s\n",
 477                 (pd->flags & EE_ADDR8) ? 8 : 16,
 478                 (pd->flags & EE_READONLY) ? "(readonly)" : "");
 479
 480         if (!(pd->flags & EE_READONLY)) {
 481                 if (device_create_file(&spi->dev, &dev_attr_erase))
 482                         dev_err(&spi->dev, "can't create erase interface\n");
 483         }
 484
 485         spi_set_drvdata(spi, edev);
 486         return 0;
 487 }
 488
 489 static int eeprom_93xx46_remove(struct spi_device *spi)
 490 {
 491         struct eeprom_93xx46_dev *edev = spi_get_drvdata(spi);
 492
 493         if (!(edev->pdata->flags & EE_READONLY))
 494                 device_remove_file(&spi->dev, &dev_attr_erase);
 495
 496         return 0;
 497 }
 498
 499 static struct spi_driver eeprom_93xx46_driver = {
 500         .driver = {
 501                 .name   = "93xx46",
 502                 .of_match_table = of_match_ptr(eeprom_93xx46_of_table),
 503         },
 504         .probe          = eeprom_93xx46_probe,
 505         .remove         = eeprom_93xx46_remove,
 506 };
 507
 508 module_spi_driver(eeprom_93xx46_driver);
 509
 510 MODULE_LICENSE("GPL");
 511 MODULE_DESCRIPTION("Driver for 93xx46 EEPROMs");
 512 MODULE_AUTHOR("Anatolij Gustschin <[email protected]>");
 513 MODULE_ALIAS("spi:93xx46");