1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Driver for most of the SPI EEPROMs, such as Atmel AT25 models 4 * and Cypress FRAMs FM25 models. 5 * 6 * Copyright (C) 2006 David Brownell 7 */ 8 9 #include <linux/bits.h> 10 #include <linux/delay.h> 11 #include <linux/device.h> 12 #include <linux/kernel.h> 13 #include <linux/module.h> 14 #include <linux/property.h> 15 #include <linux/sched.h> 16 #include <linux/slab.h> 17 18 #include <linux/spi/eeprom.h> 19 #include <linux/spi/spi.h> 20 21 #include <linux/nvmem-provider.h> 22 23 /* 24 * NOTE: this is an *EEPROM* driver. The vagaries of product naming 25 * mean that some AT25 products are EEPROMs, and others are FLASH. 26 * Handle FLASH chips with the drivers/mtd/devices/m25p80.c driver, 27 * not this one! 28 * 29 * EEPROMs that can be used with this driver include, for example: 30 * AT25M02, AT25128B 31 */ 32 33 #define FM25_SN_LEN 8 /* serial number length */ 34 #define EE_MAXADDRLEN 3 /* 24 bit addresses, up to 2 MBytes */ 35 36 struct at25_data { 37 struct spi_eeprom chip; 38 struct spi_device *spi; 39 struct mutex lock; 40 unsigned addrlen; 41 struct nvmem_config nvmem_config; 42 struct nvmem_device *nvmem; 43 u8 sernum[FM25_SN_LEN]; 44 u8 command[EE_MAXADDRLEN + 1]; 45 }; 46 47 #define AT25_WREN 0x06 /* latch the write enable */ 48 #define AT25_WRDI 0x04 /* reset the write enable */ 49 #define AT25_RDSR 0x05 /* read status register */ 50 #define AT25_WRSR 0x01 /* write status register */ 51 #define AT25_READ 0x03 /* read byte(s) */ 52 #define AT25_WRITE 0x02 /* write byte(s)/sector */ 53 #define FM25_SLEEP 0xb9 /* enter sleep mode */ 54 #define FM25_RDID 0x9f /* read device ID */ 55 #define FM25_RDSN 0xc3 /* read S/N */ 56 57 #define AT25_SR_nRDY 0x01 /* nRDY = write-in-progress */ 58 #define AT25_SR_WEN 0x02 /* write enable (latched) */ 59 #define AT25_SR_BP0 0x04 /* BP for software writeprotect */ 60 #define AT25_SR_BP1 0x08 61 #define AT25_SR_WPEN 0x80 /* writeprotect enable */ 62 63 #define AT25_INSTR_BIT3 0x08 /* additional address bit in instr */ 64 65 #define FM25_ID_LEN 9 /* ID length */ 66 67 /* 68 * Specs often allow 5ms for a page write, sometimes 20ms; 69 * it's important to recover from write timeouts. 70 */ 71 #define EE_TIMEOUT 25 72 73 /*-------------------------------------------------------------------------*/ 74 75 #define io_limit PAGE_SIZE /* bytes */ 76 77 static int at25_ee_read(void *priv, unsigned int offset, 78 void *val, size_t count) 79 { 80 struct at25_data *at25 = priv; 81 char *buf = val; 82 size_t max_chunk = spi_max_transfer_size(at25->spi); 83 unsigned int msg_offset = offset; 84 size_t bytes_left = count; 85 size_t segment; 86 u8 *cp; 87 ssize_t status; 88 struct spi_transfer t[2]; 89 struct spi_message m; 90 u8 instr; 91 92 if (unlikely(offset >= at25->chip.byte_len)) 93 return -EINVAL; 94 if ((offset + count) > at25->chip.byte_len) 95 count = at25->chip.byte_len - offset; 96 if (unlikely(!count)) 97 return -EINVAL; 98 99 do { 100 segment = min(bytes_left, max_chunk); 101 cp = at25->command; 102 103 instr = AT25_READ; 104 if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR) 105 if (msg_offset >= BIT(at25->addrlen * 8)) 106 instr |= AT25_INSTR_BIT3; 107 108 mutex_lock(&at25->lock); 109 110 *cp++ = instr; 111 112 /* 8/16/24-bit address is written MSB first */ 113 switch (at25->addrlen) { 114 default: /* case 3 */ 115 *cp++ = msg_offset >> 16; 116 fallthrough; 117 case 2: 118 *cp++ = msg_offset >> 8; 119 fallthrough; 120 case 1: 121 case 0: /* can't happen: for better code generation */ 122 *cp++ = msg_offset >> 0; 123 } 124 125 spi_message_init(&m); 126 memset(t, 0, sizeof(t)); 127 128 t[0].tx_buf = at25->command; 129 t[0].len = at25->addrlen + 1; 130 spi_message_add_tail(&t[0], &m); 131 132 t[1].rx_buf = buf; 133 t[1].len = segment; 134 spi_message_add_tail(&t[1], &m); 135 136 status = spi_sync(at25->spi, &m); 137 138 mutex_unlock(&at25->lock); 139 140 if (status) 141 return status; 142 143 msg_offset += segment; 144 buf += segment; 145 bytes_left -= segment; 146 } while (bytes_left > 0); 147 148 dev_dbg(&at25->spi->dev, "read %zu bytes at %d\n", 149 count, offset); 150 return 0; 151 } 152 153 /* Read extra registers as ID or serial number */ 154 static int fm25_aux_read(struct at25_data *at25, u8 *buf, uint8_t command, 155 int len) 156 { 157 int status; 158 struct spi_transfer t[2]; 159 struct spi_message m; 160 161 spi_message_init(&m); 162 memset(t, 0, sizeof(t)); 163 164 t[0].tx_buf = at25->command; 165 t[0].len = 1; 166 spi_message_add_tail(&t[0], &m); 167 168 t[1].rx_buf = buf; 169 t[1].len = len; 170 spi_message_add_tail(&t[1], &m); 171 172 mutex_lock(&at25->lock); 173 174 at25->command[0] = command; 175 176 status = spi_sync(at25->spi, &m); 177 dev_dbg(&at25->spi->dev, "read %d aux bytes --> %d\n", len, status); 178 179 mutex_unlock(&at25->lock); 180 return status; 181 } 182 183 static ssize_t sernum_show(struct device *dev, struct device_attribute *attr, char *buf) 184 { 185 struct at25_data *at25; 186 187 at25 = dev_get_drvdata(dev); 188 return sysfs_emit(buf, "%*ph\n", (int)sizeof(at25->sernum), at25->sernum); 189 } 190 static DEVICE_ATTR_RO(sernum); 191 192 static struct attribute *sernum_attrs[] = { 193 &dev_attr_sernum.attr, 194 NULL, 195 }; 196 ATTRIBUTE_GROUPS(sernum); 197 198 static int at25_ee_write(void *priv, unsigned int off, void *val, size_t count) 199 { 200 struct at25_data *at25 = priv; 201 size_t maxsz = spi_max_transfer_size(at25->spi); 202 const char *buf = val; 203 int status = 0; 204 unsigned buf_size; 205 u8 *bounce; 206 207 if (unlikely(off >= at25->chip.byte_len)) 208 return -EFBIG; 209 if ((off + count) > at25->chip.byte_len) 210 count = at25->chip.byte_len - off; 211 if (unlikely(!count)) 212 return -EINVAL; 213 214 /* Temp buffer starts with command and address */ 215 buf_size = at25->chip.page_size; 216 if (buf_size > io_limit) 217 buf_size = io_limit; 218 bounce = kmalloc(buf_size + at25->addrlen + 1, GFP_KERNEL); 219 if (!bounce) 220 return -ENOMEM; 221 222 /* 223 * For write, rollover is within the page ... so we write at 224 * most one page, then manually roll over to the next page. 225 */ 226 mutex_lock(&at25->lock); 227 do { 228 unsigned long timeout, retries; 229 unsigned segment; 230 unsigned offset = off; 231 u8 *cp = bounce; 232 int sr; 233 u8 instr; 234 235 *cp = AT25_WREN; 236 status = spi_write(at25->spi, cp, 1); 237 if (status < 0) { 238 dev_dbg(&at25->spi->dev, "WREN --> %d\n", status); 239 break; 240 } 241 242 instr = AT25_WRITE; 243 if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR) 244 if (offset >= BIT(at25->addrlen * 8)) 245 instr |= AT25_INSTR_BIT3; 246 *cp++ = instr; 247 248 /* 8/16/24-bit address is written MSB first */ 249 switch (at25->addrlen) { 250 default: /* case 3 */ 251 *cp++ = offset >> 16; 252 fallthrough; 253 case 2: 254 *cp++ = offset >> 8; 255 fallthrough; 256 case 1: 257 case 0: /* can't happen: for better code generation */ 258 *cp++ = offset >> 0; 259 } 260 261 /* Write as much of a page as we can */ 262 segment = buf_size - (offset % buf_size); 263 if (segment > count) 264 segment = count; 265 if (segment > maxsz) 266 segment = maxsz; 267 memcpy(cp, buf, segment); 268 status = spi_write(at25->spi, bounce, 269 segment + at25->addrlen + 1); 270 dev_dbg(&at25->spi->dev, "write %u bytes at %u --> %d\n", 271 segment, offset, status); 272 if (status < 0) 273 break; 274 275 /* 276 * REVISIT this should detect (or prevent) failed writes 277 * to read-only sections of the EEPROM... 278 */ 279 280 /* Wait for non-busy status */ 281 timeout = jiffies + msecs_to_jiffies(EE_TIMEOUT); 282 retries = 0; 283 do { 284 285 sr = spi_w8r8(at25->spi, AT25_RDSR); 286 if (sr < 0 || (sr & AT25_SR_nRDY)) { 287 dev_dbg(&at25->spi->dev, 288 "rdsr --> %d (%02x)\n", sr, sr); 289 /* at HZ=100, this is sloooow */ 290 msleep(1); 291 continue; 292 } 293 if (!(sr & AT25_SR_nRDY)) 294 break; 295 } while (retries++ < 3 || time_before_eq(jiffies, timeout)); 296 297 if ((sr < 0) || (sr & AT25_SR_nRDY)) { 298 dev_err(&at25->spi->dev, 299 "write %u bytes offset %u, timeout after %u msecs\n", 300 segment, offset, 301 jiffies_to_msecs(jiffies - 302 (timeout - EE_TIMEOUT))); 303 status = -ETIMEDOUT; 304 break; 305 } 306 307 off += segment; 308 buf += segment; 309 count -= segment; 310 311 } while (count > 0); 312 313 mutex_unlock(&at25->lock); 314 315 kfree(bounce); 316 return status; 317 } 318 319 /*-------------------------------------------------------------------------*/ 320 321 static int at25_fw_to_chip(struct device *dev, struct spi_eeprom *chip) 322 { 323 u32 val; 324 int err; 325 326 strscpy(chip->name, "at25", sizeof(chip->name)); 327 328 err = device_property_read_u32(dev, "size", &val); 329 if (err) 330 err = device_property_read_u32(dev, "at25,byte-len", &val); 331 if (err) { 332 dev_err(dev, "Error: missing \"size\" property\n"); 333 return err; 334 } 335 chip->byte_len = val; 336 337 err = device_property_read_u32(dev, "pagesize", &val); 338 if (err) 339 err = device_property_read_u32(dev, "at25,page-size", &val); 340 if (err) { 341 dev_err(dev, "Error: missing \"pagesize\" property\n"); 342 return err; 343 } 344 chip->page_size = val; 345 346 err = device_property_read_u32(dev, "address-width", &val); 347 if (err) { 348 err = device_property_read_u32(dev, "at25,addr-mode", &val); 349 if (err) { 350 dev_err(dev, "Error: missing \"address-width\" property\n"); 351 return err; 352 } 353 chip->flags = (u16)val; 354 } else { 355 switch (val) { 356 case 9: 357 chip->flags |= EE_INSTR_BIT3_IS_ADDR; 358 fallthrough; 359 case 8: 360 chip->flags |= EE_ADDR1; 361 break; 362 case 16: 363 chip->flags |= EE_ADDR2; 364 break; 365 case 24: 366 chip->flags |= EE_ADDR3; 367 break; 368 default: 369 dev_err(dev, 370 "Error: bad \"address-width\" property: %u\n", 371 val); 372 return -ENODEV; 373 } 374 if (device_property_present(dev, "read-only")) 375 chip->flags |= EE_READONLY; 376 } 377 return 0; 378 } 379 380 static int at25_fram_to_chip(struct device *dev, struct spi_eeprom *chip) 381 { 382 struct at25_data *at25 = container_of(chip, struct at25_data, chip); 383 u8 sernum[FM25_SN_LEN]; 384 u8 id[FM25_ID_LEN]; 385 int i; 386 387 strscpy(chip->name, "fm25", sizeof(chip->name)); 388 389 /* Get ID of chip */ 390 fm25_aux_read(at25, id, FM25_RDID, FM25_ID_LEN); 391 if (id[6] != 0xc2) { 392 dev_err(dev, "Error: no Cypress FRAM (id %02x)\n", id[6]); 393 return -ENODEV; 394 } 395 /* Set size found in ID */ 396 if (id[7] < 0x21 || id[7] > 0x26) { 397 dev_err(dev, "Error: unsupported size (id %02x)\n", id[7]); 398 return -ENODEV; 399 } 400 401 chip->byte_len = BIT(id[7] - 0x21 + 4) * 1024; 402 if (chip->byte_len > 64 * 1024) 403 chip->flags |= EE_ADDR3; 404 else 405 chip->flags |= EE_ADDR2; 406 407 if (id[8]) { 408 fm25_aux_read(at25, sernum, FM25_RDSN, FM25_SN_LEN); 409 /* Swap byte order */ 410 for (i = 0; i < FM25_SN_LEN; i++) 411 at25->sernum[i] = sernum[FM25_SN_LEN - 1 - i]; 412 } 413 414 chip->page_size = PAGE_SIZE; 415 return 0; 416 } 417 418 static const struct of_device_id at25_of_match[] = { 419 { .compatible = "atmel,at25" }, 420 { .compatible = "cypress,fm25" }, 421 { } 422 }; 423 MODULE_DEVICE_TABLE(of, at25_of_match); 424 425 static const struct spi_device_id at25_spi_ids[] = { 426 { .name = "at25" }, 427 { .name = "fm25" }, 428 { } 429 }; 430 MODULE_DEVICE_TABLE(spi, at25_spi_ids); 431 432 static int at25_probe(struct spi_device *spi) 433 { 434 struct at25_data *at25 = NULL; 435 int err; 436 int sr; 437 struct spi_eeprom *pdata; 438 bool is_fram; 439 440 /* 441 * Ping the chip ... the status register is pretty portable, 442 * unlike probing manufacturer IDs. We do expect that system 443 * firmware didn't write it in the past few milliseconds! 444 */ 445 sr = spi_w8r8(spi, AT25_RDSR); 446 if (sr < 0 || sr & AT25_SR_nRDY) { 447 dev_dbg(&spi->dev, "rdsr --> %d (%02x)\n", sr, sr); 448 return -ENXIO; 449 } 450 451 at25 = devm_kzalloc(&spi->dev, sizeof(*at25), GFP_KERNEL); 452 if (!at25) 453 return -ENOMEM; 454 455 mutex_init(&at25->lock); 456 at25->spi = spi; 457 spi_set_drvdata(spi, at25); 458 459 is_fram = fwnode_device_is_compatible(dev_fwnode(&spi->dev), "cypress,fm25"); 460 461 /* Chip description */ 462 pdata = dev_get_platdata(&spi->dev); 463 if (pdata) { 464 at25->chip = *pdata; 465 } else { 466 if (is_fram) 467 err = at25_fram_to_chip(&spi->dev, &at25->chip); 468 else 469 err = at25_fw_to_chip(&spi->dev, &at25->chip); 470 if (err) 471 return err; 472 } 473 474 /* For now we only support 8/16/24 bit addressing */ 475 if (at25->chip.flags & EE_ADDR1) 476 at25->addrlen = 1; 477 else if (at25->chip.flags & EE_ADDR2) 478 at25->addrlen = 2; 479 else if (at25->chip.flags & EE_ADDR3) 480 at25->addrlen = 3; 481 else { 482 dev_dbg(&spi->dev, "unsupported address type\n"); 483 return -EINVAL; 484 } 485 486 at25->nvmem_config.type = is_fram ? NVMEM_TYPE_FRAM : NVMEM_TYPE_EEPROM; 487 at25->nvmem_config.name = dev_name(&spi->dev); 488 at25->nvmem_config.dev = &spi->dev; 489 at25->nvmem_config.read_only = at25->chip.flags & EE_READONLY; 490 at25->nvmem_config.root_only = true; 491 at25->nvmem_config.owner = THIS_MODULE; 492 at25->nvmem_config.compat = true; 493 at25->nvmem_config.base_dev = &spi->dev; 494 at25->nvmem_config.reg_read = at25_ee_read; 495 at25->nvmem_config.reg_write = at25_ee_write; 496 at25->nvmem_config.priv = at25; 497 at25->nvmem_config.stride = 1; 498 at25->nvmem_config.word_size = 1; 499 at25->nvmem_config.size = at25->chip.byte_len; 500 501 at25->nvmem = devm_nvmem_register(&spi->dev, &at25->nvmem_config); 502 if (IS_ERR(at25->nvmem)) 503 return PTR_ERR(at25->nvmem); 504 505 dev_info(&spi->dev, "%d %s %s %s%s, pagesize %u\n", 506 (at25->chip.byte_len < 1024) ? 507 at25->chip.byte_len : (at25->chip.byte_len / 1024), 508 (at25->chip.byte_len < 1024) ? "Byte" : "KByte", 509 at25->chip.name, is_fram ? "fram" : "eeprom", 510 (at25->chip.flags & EE_READONLY) ? " (readonly)" : "", 511 at25->chip.page_size); 512 return 0; 513 } 514 515 /*-------------------------------------------------------------------------*/ 516 517 static struct spi_driver at25_driver = { 518 .driver = { 519 .name = "at25", 520 .of_match_table = at25_of_match, 521 .dev_groups = sernum_groups, 522 }, 523 .probe = at25_probe, 524 .id_table = at25_spi_ids, 525 }; 526 527 module_spi_driver(at25_driver); 528 529 MODULE_DESCRIPTION("Driver for most SPI EEPROMs"); 530 MODULE_AUTHOR("David Brownell"); 531 MODULE_LICENSE("GPL"); 532 MODULE_ALIAS("spi:at25"); 533