David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 1 | /* |
| 2 | * at25.c -- support most SPI EEPROMs, such as Atmel AT25 models |
| 3 | * |
| 4 | * Copyright (C) 2006 David Brownell |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License as published by |
| 8 | * the Free Software Foundation; either version 2 of the License, or |
| 9 | * (at your option) any later version. |
| 10 | */ |
| 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/device.h> |
| 18 | #include <linux/sched.h> |
| 19 | |
| 20 | #include <linux/spi/spi.h> |
| 21 | #include <linux/spi/eeprom.h> |
| 22 | |
| 23 | |
David Brownell | 3f86f14 | 2007-12-04 23:45:10 -0800 | [diff] [blame] | 24 | /* |
| 25 | * NOTE: this is an *EEPROM* driver. The vagaries of product naming |
| 26 | * mean that some AT25 products are EEPROMs, and others are FLASH. |
| 27 | * Handle FLASH chips with the drivers/mtd/devices/m25p80.c driver, |
| 28 | * not this one! |
| 29 | */ |
| 30 | |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 31 | struct at25_data { |
| 32 | struct spi_device *spi; |
David Brownell | 14dd1ff | 2009-04-02 16:56:58 -0700 | [diff] [blame] | 33 | struct memory_accessor mem; |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 34 | struct mutex lock; |
| 35 | struct spi_eeprom chip; |
| 36 | struct bin_attribute bin; |
| 37 | unsigned addrlen; |
| 38 | }; |
| 39 | |
| 40 | #define AT25_WREN 0x06 /* latch the write enable */ |
| 41 | #define AT25_WRDI 0x04 /* reset the write enable */ |
| 42 | #define AT25_RDSR 0x05 /* read status register */ |
| 43 | #define AT25_WRSR 0x01 /* write status register */ |
| 44 | #define AT25_READ 0x03 /* read byte(s) */ |
| 45 | #define AT25_WRITE 0x02 /* write byte(s)/sector */ |
| 46 | |
| 47 | #define AT25_SR_nRDY 0x01 /* nRDY = write-in-progress */ |
| 48 | #define AT25_SR_WEN 0x02 /* write enable (latched) */ |
| 49 | #define AT25_SR_BP0 0x04 /* BP for software writeprotect */ |
| 50 | #define AT25_SR_BP1 0x08 |
| 51 | #define AT25_SR_WPEN 0x80 /* writeprotect enable */ |
| 52 | |
| 53 | |
| 54 | #define EE_MAXADDRLEN 3 /* 24 bit addresses, up to 2 MBytes */ |
| 55 | |
| 56 | /* Specs often allow 5 msec for a page write, sometimes 20 msec; |
| 57 | * it's important to recover from write timeouts. |
| 58 | */ |
| 59 | #define EE_TIMEOUT 25 |
| 60 | |
| 61 | /*-------------------------------------------------------------------------*/ |
| 62 | |
| 63 | #define io_limit PAGE_SIZE /* bytes */ |
| 64 | |
| 65 | static ssize_t |
| 66 | at25_ee_read( |
| 67 | struct at25_data *at25, |
| 68 | char *buf, |
| 69 | unsigned offset, |
| 70 | size_t count |
| 71 | ) |
| 72 | { |
| 73 | u8 command[EE_MAXADDRLEN + 1]; |
| 74 | u8 *cp; |
| 75 | ssize_t status; |
| 76 | struct spi_transfer t[2]; |
| 77 | struct spi_message m; |
| 78 | |
David Brownell | 14dd1ff | 2009-04-02 16:56:58 -0700 | [diff] [blame] | 79 | if (unlikely(offset >= at25->bin.size)) |
| 80 | return 0; |
| 81 | if ((offset + count) > at25->bin.size) |
| 82 | count = at25->bin.size - offset; |
| 83 | if (unlikely(!count)) |
| 84 | return count; |
| 85 | |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 86 | cp = command; |
| 87 | *cp++ = AT25_READ; |
| 88 | |
| 89 | /* 8/16/24-bit address is written MSB first */ |
| 90 | switch (at25->addrlen) { |
| 91 | default: /* case 3 */ |
| 92 | *cp++ = offset >> 16; |
| 93 | case 2: |
| 94 | *cp++ = offset >> 8; |
| 95 | case 1: |
| 96 | case 0: /* can't happen: for better codegen */ |
| 97 | *cp++ = offset >> 0; |
| 98 | } |
| 99 | |
| 100 | spi_message_init(&m); |
| 101 | memset(t, 0, sizeof t); |
| 102 | |
| 103 | t[0].tx_buf = command; |
| 104 | t[0].len = at25->addrlen + 1; |
| 105 | spi_message_add_tail(&t[0], &m); |
| 106 | |
| 107 | t[1].rx_buf = buf; |
| 108 | t[1].len = count; |
| 109 | spi_message_add_tail(&t[1], &m); |
| 110 | |
| 111 | mutex_lock(&at25->lock); |
| 112 | |
| 113 | /* Read it all at once. |
| 114 | * |
| 115 | * REVISIT that's potentially a problem with large chips, if |
| 116 | * other devices on the bus need to be accessed regularly or |
| 117 | * this chip is clocked very slowly |
| 118 | */ |
| 119 | status = spi_sync(at25->spi, &m); |
| 120 | dev_dbg(&at25->spi->dev, |
| 121 | "read %Zd bytes at %d --> %d\n", |
| 122 | count, offset, (int) status); |
| 123 | |
| 124 | mutex_unlock(&at25->lock); |
| 125 | return status ? status : count; |
| 126 | } |
| 127 | |
| 128 | static ssize_t |
Chris Wright | 2c3c8be | 2010-05-12 18:28:57 -0700 | [diff] [blame] | 129 | at25_bin_read(struct file *filp, struct kobject *kobj, |
| 130 | struct bin_attribute *bin_attr, |
Zhang Rui | 91a6902 | 2007-06-09 13:57:22 +0800 | [diff] [blame] | 131 | char *buf, loff_t off, size_t count) |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 132 | { |
| 133 | struct device *dev; |
| 134 | struct at25_data *at25; |
| 135 | |
| 136 | dev = container_of(kobj, struct device, kobj); |
| 137 | at25 = dev_get_drvdata(dev); |
| 138 | |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 139 | return at25_ee_read(at25, buf, off, count); |
| 140 | } |
| 141 | |
| 142 | |
| 143 | static ssize_t |
Geert Uytterhoeven | 4cafbd0 | 2009-04-13 14:40:07 -0700 | [diff] [blame] | 144 | at25_ee_write(struct at25_data *at25, const char *buf, loff_t off, |
| 145 | size_t count) |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 146 | { |
| 147 | ssize_t status = 0; |
| 148 | unsigned written = 0; |
| 149 | unsigned buf_size; |
| 150 | u8 *bounce; |
| 151 | |
David Brownell | 14dd1ff | 2009-04-02 16:56:58 -0700 | [diff] [blame] | 152 | if (unlikely(off >= at25->bin.size)) |
| 153 | return -EFBIG; |
| 154 | if ((off + count) > at25->bin.size) |
| 155 | count = at25->bin.size - off; |
| 156 | if (unlikely(!count)) |
| 157 | return count; |
| 158 | |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 159 | /* Temp buffer starts with command and address */ |
| 160 | buf_size = at25->chip.page_size; |
| 161 | if (buf_size > io_limit) |
| 162 | buf_size = io_limit; |
| 163 | bounce = kmalloc(buf_size + at25->addrlen + 1, GFP_KERNEL); |
| 164 | if (!bounce) |
| 165 | return -ENOMEM; |
| 166 | |
| 167 | /* For write, rollover is within the page ... so we write at |
| 168 | * most one page, then manually roll over to the next page. |
| 169 | */ |
| 170 | bounce[0] = AT25_WRITE; |
| 171 | mutex_lock(&at25->lock); |
| 172 | do { |
| 173 | unsigned long timeout, retries; |
| 174 | unsigned segment; |
| 175 | unsigned offset = (unsigned) off; |
| 176 | u8 *cp = bounce + 1; |
Sebastian Heutling | f0d8367 | 2009-07-29 15:04:05 -0700 | [diff] [blame] | 177 | int sr; |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 178 | |
| 179 | *cp = AT25_WREN; |
| 180 | status = spi_write(at25->spi, cp, 1); |
| 181 | if (status < 0) { |
| 182 | dev_dbg(&at25->spi->dev, "WREN --> %d\n", |
| 183 | (int) status); |
| 184 | break; |
| 185 | } |
| 186 | |
| 187 | /* 8/16/24-bit address is written MSB first */ |
| 188 | switch (at25->addrlen) { |
| 189 | default: /* case 3 */ |
| 190 | *cp++ = offset >> 16; |
| 191 | case 2: |
| 192 | *cp++ = offset >> 8; |
| 193 | case 1: |
| 194 | case 0: /* can't happen: for better codegen */ |
| 195 | *cp++ = offset >> 0; |
| 196 | } |
| 197 | |
| 198 | /* Write as much of a page as we can */ |
| 199 | segment = buf_size - (offset % buf_size); |
| 200 | if (segment > count) |
| 201 | segment = count; |
| 202 | memcpy(cp, buf, segment); |
| 203 | status = spi_write(at25->spi, bounce, |
| 204 | segment + at25->addrlen + 1); |
| 205 | dev_dbg(&at25->spi->dev, |
| 206 | "write %u bytes at %u --> %d\n", |
| 207 | segment, offset, (int) status); |
| 208 | if (status < 0) |
| 209 | break; |
| 210 | |
| 211 | /* REVISIT this should detect (or prevent) failed writes |
| 212 | * to readonly sections of the EEPROM... |
| 213 | */ |
| 214 | |
| 215 | /* Wait for non-busy status */ |
| 216 | timeout = jiffies + msecs_to_jiffies(EE_TIMEOUT); |
| 217 | retries = 0; |
| 218 | do { |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 219 | |
| 220 | sr = spi_w8r8(at25->spi, AT25_RDSR); |
| 221 | if (sr < 0 || (sr & AT25_SR_nRDY)) { |
| 222 | dev_dbg(&at25->spi->dev, |
| 223 | "rdsr --> %d (%02x)\n", sr, sr); |
| 224 | /* at HZ=100, this is sloooow */ |
| 225 | msleep(1); |
| 226 | continue; |
| 227 | } |
| 228 | if (!(sr & AT25_SR_nRDY)) |
| 229 | break; |
| 230 | } while (retries++ < 3 || time_before_eq(jiffies, timeout)); |
| 231 | |
Sebastian Heutling | f0d8367 | 2009-07-29 15:04:05 -0700 | [diff] [blame] | 232 | if ((sr < 0) || (sr & AT25_SR_nRDY)) { |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 233 | dev_err(&at25->spi->dev, |
| 234 | "write %d bytes offset %d, " |
| 235 | "timeout after %u msecs\n", |
| 236 | segment, offset, |
| 237 | jiffies_to_msecs(jiffies - |
| 238 | (timeout - EE_TIMEOUT))); |
| 239 | status = -ETIMEDOUT; |
| 240 | break; |
| 241 | } |
| 242 | |
| 243 | off += segment; |
| 244 | buf += segment; |
| 245 | count -= segment; |
| 246 | written += segment; |
| 247 | |
| 248 | } while (count > 0); |
| 249 | |
| 250 | mutex_unlock(&at25->lock); |
| 251 | |
| 252 | kfree(bounce); |
| 253 | return written ? written : status; |
| 254 | } |
| 255 | |
| 256 | static ssize_t |
Chris Wright | 2c3c8be | 2010-05-12 18:28:57 -0700 | [diff] [blame] | 257 | at25_bin_write(struct file *filp, struct kobject *kobj, |
| 258 | struct bin_attribute *bin_attr, |
Zhang Rui | 91a6902 | 2007-06-09 13:57:22 +0800 | [diff] [blame] | 259 | char *buf, loff_t off, size_t count) |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 260 | { |
| 261 | struct device *dev; |
| 262 | struct at25_data *at25; |
| 263 | |
| 264 | dev = container_of(kobj, struct device, kobj); |
| 265 | at25 = dev_get_drvdata(dev); |
| 266 | |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 267 | return at25_ee_write(at25, buf, off, count); |
| 268 | } |
| 269 | |
| 270 | /*-------------------------------------------------------------------------*/ |
| 271 | |
David Brownell | 14dd1ff | 2009-04-02 16:56:58 -0700 | [diff] [blame] | 272 | /* Let in-kernel code access the eeprom data. */ |
| 273 | |
| 274 | static ssize_t at25_mem_read(struct memory_accessor *mem, char *buf, |
| 275 | off_t offset, size_t count) |
| 276 | { |
| 277 | struct at25_data *at25 = container_of(mem, struct at25_data, mem); |
| 278 | |
| 279 | return at25_ee_read(at25, buf, offset, count); |
| 280 | } |
| 281 | |
Geert Uytterhoeven | 4cafbd0 | 2009-04-13 14:40:07 -0700 | [diff] [blame] | 282 | static ssize_t at25_mem_write(struct memory_accessor *mem, const char *buf, |
David Brownell | 14dd1ff | 2009-04-02 16:56:58 -0700 | [diff] [blame] | 283 | off_t offset, size_t count) |
| 284 | { |
| 285 | struct at25_data *at25 = container_of(mem, struct at25_data, mem); |
| 286 | |
| 287 | return at25_ee_write(at25, buf, offset, count); |
| 288 | } |
| 289 | |
| 290 | /*-------------------------------------------------------------------------*/ |
| 291 | |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 292 | static int at25_probe(struct spi_device *spi) |
| 293 | { |
| 294 | struct at25_data *at25 = NULL; |
| 295 | const struct spi_eeprom *chip; |
| 296 | int err; |
| 297 | int sr; |
| 298 | int addrlen; |
| 299 | |
| 300 | /* Chip description */ |
| 301 | chip = spi->dev.platform_data; |
| 302 | if (!chip) { |
| 303 | dev_dbg(&spi->dev, "no chip description\n"); |
| 304 | err = -ENODEV; |
| 305 | goto fail; |
| 306 | } |
| 307 | |
| 308 | /* For now we only support 8/16/24 bit addressing */ |
| 309 | if (chip->flags & EE_ADDR1) |
| 310 | addrlen = 1; |
| 311 | else if (chip->flags & EE_ADDR2) |
| 312 | addrlen = 2; |
| 313 | else if (chip->flags & EE_ADDR3) |
| 314 | addrlen = 3; |
| 315 | else { |
| 316 | dev_dbg(&spi->dev, "unsupported address type\n"); |
| 317 | err = -EINVAL; |
| 318 | goto fail; |
| 319 | } |
| 320 | |
| 321 | /* Ping the chip ... the status register is pretty portable, |
| 322 | * unlike probing manufacturer IDs. We do expect that system |
| 323 | * firmware didn't write it in the past few milliseconds! |
| 324 | */ |
| 325 | sr = spi_w8r8(spi, AT25_RDSR); |
| 326 | if (sr < 0 || sr & AT25_SR_nRDY) { |
Atsushi Nemoto | c6ca97d | 2007-03-16 13:38:20 -0800 | [diff] [blame] | 327 | dev_dbg(&spi->dev, "rdsr --> %d (%02x)\n", sr, sr); |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 328 | err = -ENXIO; |
| 329 | goto fail; |
| 330 | } |
| 331 | |
| 332 | if (!(at25 = kzalloc(sizeof *at25, GFP_KERNEL))) { |
| 333 | err = -ENOMEM; |
| 334 | goto fail; |
| 335 | } |
| 336 | |
| 337 | mutex_init(&at25->lock); |
| 338 | at25->chip = *chip; |
| 339 | at25->spi = spi_dev_get(spi); |
| 340 | dev_set_drvdata(&spi->dev, at25); |
| 341 | at25->addrlen = addrlen; |
| 342 | |
| 343 | /* Export the EEPROM bytes through sysfs, since that's convenient. |
David Brownell | 14dd1ff | 2009-04-02 16:56:58 -0700 | [diff] [blame] | 344 | * And maybe to other kernel code; it might hold a board's Ethernet |
| 345 | * address, or board-specific calibration data generated on the |
| 346 | * manufacturing floor. |
| 347 | * |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 348 | * Default to root-only access to the data; EEPROMs often hold data |
| 349 | * that's sensitive for read and/or write, like ethernet addresses, |
| 350 | * security codes, board-specific manufacturing calibrations, etc. |
| 351 | */ |
Wolfram Sang | f937331 | 2010-03-15 01:29:41 +0100 | [diff] [blame] | 352 | sysfs_bin_attr_init(&at25->bin); |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 353 | at25->bin.attr.name = "eeprom"; |
| 354 | at25->bin.attr.mode = S_IRUSR; |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 355 | at25->bin.read = at25_bin_read; |
David Brownell | 14dd1ff | 2009-04-02 16:56:58 -0700 | [diff] [blame] | 356 | at25->mem.read = at25_mem_read; |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 357 | |
| 358 | at25->bin.size = at25->chip.byte_len; |
| 359 | if (!(chip->flags & EE_READONLY)) { |
| 360 | at25->bin.write = at25_bin_write; |
| 361 | at25->bin.attr.mode |= S_IWUSR; |
David Brownell | 14dd1ff | 2009-04-02 16:56:58 -0700 | [diff] [blame] | 362 | at25->mem.write = at25_mem_write; |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 363 | } |
| 364 | |
| 365 | err = sysfs_create_bin_file(&spi->dev.kobj, &at25->bin); |
| 366 | if (err) |
| 367 | goto fail; |
| 368 | |
David Brownell | 14dd1ff | 2009-04-02 16:56:58 -0700 | [diff] [blame] | 369 | if (chip->setup) |
| 370 | chip->setup(&at25->mem, chip->context); |
| 371 | |
David Brownell | b587b13 | 2007-02-12 00:52:48 -0800 | [diff] [blame] | 372 | dev_info(&spi->dev, "%Zd %s %s eeprom%s, pagesize %u\n", |
| 373 | (at25->bin.size < 1024) |
| 374 | ? at25->bin.size |
| 375 | : (at25->bin.size / 1024), |
| 376 | (at25->bin.size < 1024) ? "Byte" : "KByte", |
| 377 | at25->chip.name, |
| 378 | (chip->flags & EE_READONLY) ? " (readonly)" : "", |
| 379 | at25->chip.page_size); |
| 380 | return 0; |
| 381 | fail: |
| 382 | dev_dbg(&spi->dev, "probe err %d\n", err); |
| 383 | kfree(at25); |
| 384 | return err; |
| 385 | } |
| 386 | |
| 387 | static int __devexit at25_remove(struct spi_device *spi) |
| 388 | { |
| 389 | struct at25_data *at25; |
| 390 | |
| 391 | at25 = dev_get_drvdata(&spi->dev); |
| 392 | sysfs_remove_bin_file(&spi->dev.kobj, &at25->bin); |
| 393 | kfree(at25); |
| 394 | return 0; |
| 395 | } |
| 396 | |
| 397 | /*-------------------------------------------------------------------------*/ |
| 398 | |
| 399 | static struct spi_driver at25_driver = { |
| 400 | .driver = { |
| 401 | .name = "at25", |
| 402 | .owner = THIS_MODULE, |
| 403 | }, |
| 404 | .probe = at25_probe, |
| 405 | .remove = __devexit_p(at25_remove), |
| 406 | }; |
| 407 | |
| 408 | static int __init at25_init(void) |
| 409 | { |
| 410 | return spi_register_driver(&at25_driver); |
| 411 | } |
| 412 | module_init(at25_init); |
| 413 | |
| 414 | static void __exit at25_exit(void) |
| 415 | { |
| 416 | spi_unregister_driver(&at25_driver); |
| 417 | } |
| 418 | module_exit(at25_exit); |
| 419 | |
| 420 | MODULE_DESCRIPTION("Driver for most SPI EEPROMs"); |
| 421 | MODULE_AUTHOR("David Brownell"); |
| 422 | MODULE_LICENSE("GPL"); |
Anton Vorontsov | e0626e3 | 2009-09-22 16:46:08 -0700 | [diff] [blame] | 423 | MODULE_ALIAS("spi:at25"); |