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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/mod_devicetable.h>
19#include <linux/log2.h>
20#include <linux/bitops.h>
21#include <linux/jiffies.h>
22#include <linux/of.h>
23#include <linux/acpi.h>
24#include <linux/i2c.h>
25#include <linux/nvmem-provider.h>
26#include <linux/regmap.h>
27#include <linux/platform_data/at24.h>
28
29/*
30 * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
31 * Differences between different vendor product lines (like Atmel AT24C or
32 * MicroChip 24LC, etc) won't much matter for typical read/write access.
33 * There are also I2C RAM chips, likewise interchangeable. One example
34 * would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
35 *
36 * However, misconfiguration can lose data. "Set 16-bit memory address"
37 * to a part with 8-bit addressing will overwrite data. Writing with too
38 * big a page size also loses data. And it's not safe to assume that the
39 * conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
40 * uses 0x51, for just one example.
41 *
42 * Accordingly, explicit board-specific configuration data should be used
43 * in almost all cases. (One partial exception is an SMBus used to access
44 * "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
45 *
46 * So this driver uses "new style" I2C driver binding, expecting to be
47 * told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
48 * similar kernel-resident tables; or, configuration data coming from
49 * a bootloader.
50 *
51 * Other than binding model, current differences from "eeprom" driver are
52 * that this one handles write access and isn't restricted to 24c02 devices.
53 * It also handles larger devices (32 kbit and up) with two-byte addresses,
54 * which won't work on pure SMBus systems.
55 */
56
57struct at24_data {
58 struct at24_platform_data chip;
59 int use_smbus;
60 int use_smbus_write;
61
62 /*
63 * Lock protects against activities from other Linux tasks,
64 * but not from changes by other I2C masters.
65 */
66 struct mutex lock;
67
68 u8 *writebuf;
69 unsigned write_max;
70 unsigned num_addresses;
71
72 struct regmap_config regmap_config;
73 struct nvmem_config nvmem_config;
74 struct nvmem_device *nvmem;
75
76 /*
77 * Some chips tie up multiple I2C addresses; dummy devices reserve
78 * them for us, and we'll use them with SMBus calls.
79 */
80 struct i2c_client *client[];
81};
82
83/*
84 * This parameter is to help this driver avoid blocking other drivers out
85 * of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
86 * clock, one 256 byte read takes about 1/43 second which is excessive;
87 * but the 1/170 second it takes at 400 kHz may be quite reasonable; and
88 * at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
89 *
90 * This value is forced to be a power of two so that writes align on pages.
91 */
92static unsigned io_limit = 128;
93module_param(io_limit, uint, 0);
94MODULE_PARM_DESC(io_limit, "Maximum bytes per I/O (default 128)");
95
96/*
97 * Specs often allow 5 msec for a page write, sometimes 20 msec;
98 * it's important to recover from write timeouts.
99 */
100static unsigned write_timeout = 25;
101module_param(write_timeout, uint, 0);
102MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
103
104#define AT24_SIZE_BYTELEN 5
105#define AT24_SIZE_FLAGS 8
106
107#define AT24_BITMASK(x) (BIT(x) - 1)
108
109/* create non-zero magic value for given eeprom parameters */
110#define AT24_DEVICE_MAGIC(_len, _flags) \
111 ((1 << AT24_SIZE_FLAGS | (_flags)) \
112 << AT24_SIZE_BYTELEN | ilog2(_len))
113
114static const struct i2c_device_id at24_ids[] = {
115 /* needs 8 addresses as A0-A2 are ignored */
116 { "24c00", AT24_DEVICE_MAGIC(128 / 8, AT24_FLAG_TAKE8ADDR) },
117 /* old variants can't be handled with this generic entry! */
118 { "24c01", AT24_DEVICE_MAGIC(1024 / 8, 0) },
119 { "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) },
120 /* spd is a 24c02 in memory DIMMs */
121 { "spd", AT24_DEVICE_MAGIC(2048 / 8,
122 AT24_FLAG_READONLY | AT24_FLAG_IRUGO) },
123 { "24c04", AT24_DEVICE_MAGIC(4096 / 8, 0) },
124 /* 24rf08 quirk is handled at i2c-core */
125 { "24c08", AT24_DEVICE_MAGIC(8192 / 8, 0) },
126 { "24c16", AT24_DEVICE_MAGIC(16384 / 8, 0) },
127 { "24c32", AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16) },
128 { "24c64", AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16) },
129 { "24c128", AT24_DEVICE_MAGIC(131072 / 8, AT24_FLAG_ADDR16) },
130 { "24c256", AT24_DEVICE_MAGIC(262144 / 8, AT24_FLAG_ADDR16) },
131 { "24c512", AT24_DEVICE_MAGIC(524288 / 8, AT24_FLAG_ADDR16) },
132 { "24c1024", AT24_DEVICE_MAGIC(1048576 / 8, AT24_FLAG_ADDR16) },
133 { "at24", 0 },
134 { /* END OF LIST */ }
135};
136MODULE_DEVICE_TABLE(i2c, at24_ids);
137
138static const struct acpi_device_id at24_acpi_ids[] = {
139 { "INT3499", AT24_DEVICE_MAGIC(8192 / 8, 0) },
140 { }
141};
142MODULE_DEVICE_TABLE(acpi, at24_acpi_ids);
143
144/*-------------------------------------------------------------------------*/
145
146/*
147 * This routine supports chips which consume multiple I2C addresses. It
148 * computes the addressing information to be used for a given r/w request.
149 * Assumes that sanity checks for offset happened at sysfs-layer.
150 */
151static struct i2c_client *at24_translate_offset(struct at24_data *at24,
152 unsigned *offset)
153{
154 unsigned i;
155
156 if (at24->chip.flags & AT24_FLAG_ADDR16) {
157 i = *offset >> 16;
158 *offset &= 0xffff;
159 } else {
160 i = *offset >> 8;
161 *offset &= 0xff;
162 }
163
164 return at24->client[i];
165}
166
167static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,
168 unsigned offset, size_t count)
169{
170 struct i2c_msg msg[2];
171 u8 msgbuf[2];
172 struct i2c_client *client;
173 unsigned long timeout, read_time;
174 int status, i;
175
176 memset(msg, 0, sizeof(msg));
177
178 /*
179 * REVISIT some multi-address chips don't rollover page reads to
180 * the next slave address, so we may need to truncate the count.
181 * Those chips might need another quirk flag.
182 *
183 * If the real hardware used four adjacent 24c02 chips and that
184 * were misconfigured as one 24c08, that would be a similar effect:
185 * one "eeprom" file not four, but larger reads would fail when
186 * they crossed certain pages.
187 */
188
189 /*
190 * Slave address and byte offset derive from the offset. Always
191 * set the byte address; on a multi-master board, another master
192 * may have changed the chip's "current" address pointer.
193 */
194 client = at24_translate_offset(at24, &offset);
195
196 if (count > io_limit)
197 count = io_limit;
198
199 if (at24->use_smbus) {
200 /* Smaller eeproms can work given some SMBus extension calls */
201 if (count > I2C_SMBUS_BLOCK_MAX)
202 count = I2C_SMBUS_BLOCK_MAX;
203 } else {
204 /*
205 * When we have a better choice than SMBus calls, use a
206 * combined I2C message. Write address; then read up to
207 * io_limit data bytes. Note that read page rollover helps us
208 * here (unlike writes). msgbuf is u8 and will cast to our
209 * needs.
210 */
211 i = 0;
212 if (at24->chip.flags & AT24_FLAG_ADDR16)
213 msgbuf[i++] = offset >> 8;
214 msgbuf[i++] = offset;
215
216 msg[0].addr = client->addr;
217 msg[0].buf = msgbuf;
218 msg[0].len = i;
219
220 msg[1].addr = client->addr;
221 msg[1].flags = I2C_M_RD;
222 msg[1].buf = buf;
223 msg[1].len = count;
224 }
225
226 /*
227 * Reads fail if the previous write didn't complete yet. We may
228 * loop a few times until this one succeeds, waiting at least
229 * long enough for one entire page write to work.
230 */
231 timeout = jiffies + msecs_to_jiffies(write_timeout);
232 do {
233 read_time = jiffies;
234 if (at24->use_smbus) {
235 status = i2c_smbus_read_i2c_block_data_or_emulated(client, offset,
236 count, buf);
237 } else {
238 status = i2c_transfer(client->adapter, msg, 2);
239 if (status == 2)
240 status = count;
241 }
242 dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
243 count, offset, status, jiffies);
244
245 if (status == count)
246 return count;
247
248 /* REVISIT: at HZ=100, this is sloooow */
249 msleep(1);
250 } while (time_before(read_time, timeout));
251
252 return -ETIMEDOUT;
253}
254
255static ssize_t at24_read(struct at24_data *at24,
256 char *buf, loff_t off, size_t count)
257{
258 ssize_t retval = 0;
259
260 if (unlikely(!count))
261 return count;
262
263 /*
264 * Read data from chip, protecting against concurrent updates
265 * from this host, but not from other I2C masters.
266 */
267 mutex_lock(&at24->lock);
268
269 while (count) {
270 ssize_t status;
271
272 status = at24_eeprom_read(at24, buf, off, count);
273 if (status <= 0) {
274 if (retval == 0)
275 retval = status;
276 break;
277 }
278 buf += status;
279 off += status;
280 count -= status;
281 retval += status;
282 }
283
284 mutex_unlock(&at24->lock);
285
286 return retval;
287}
288
289/*
290 * Note that if the hardware write-protect pin is pulled high, the whole
291 * chip is normally write protected. But there are plenty of product
292 * variants here, including OTP fuses and partial chip protect.
293 *
294 * We only use page mode writes; the alternative is sloooow. This routine
295 * writes at most one page.
296 */
297static ssize_t at24_eeprom_write(struct at24_data *at24, const char *buf,
298 unsigned offset, size_t count)
299{
300 struct i2c_client *client;
301 struct i2c_msg msg;
302 ssize_t status = 0;
303 unsigned long timeout, write_time;
304 unsigned next_page;
305
306 /* Get corresponding I2C address and adjust offset */
307 client = at24_translate_offset(at24, &offset);
308
309 /* write_max is at most a page */
310 if (count > at24->write_max)
311 count = at24->write_max;
312
313 /* Never roll over backwards, to the start of this page */
314 next_page = roundup(offset + 1, at24->chip.page_size);
315 if (offset + count > next_page)
316 count = next_page - offset;
317
318 /* If we'll use I2C calls for I/O, set up the message */
319 if (!at24->use_smbus) {
320 int i = 0;
321
322 msg.addr = client->addr;
323 msg.flags = 0;
324
325 /* msg.buf is u8 and casts will mask the values */
326 msg.buf = at24->writebuf;
327 if (at24->chip.flags & AT24_FLAG_ADDR16)
328 msg.buf[i++] = offset >> 8;
329
330 msg.buf[i++] = offset;
331 memcpy(&msg.buf[i], buf, count);
332 msg.len = i + count;
333 }
334
335 /*
336 * Writes fail if the previous one didn't complete yet. We may
337 * loop a few times until this one succeeds, waiting at least
338 * long enough for one entire page write to work.
339 */
340 timeout = jiffies + msecs_to_jiffies(write_timeout);
341 do {
342 write_time = jiffies;
343 if (at24->use_smbus_write) {
344 switch (at24->use_smbus_write) {
345 case I2C_SMBUS_I2C_BLOCK_DATA:
346 status = i2c_smbus_write_i2c_block_data(client,
347 offset, count, buf);
348 break;
349 case I2C_SMBUS_BYTE_DATA:
350 status = i2c_smbus_write_byte_data(client,
351 offset, buf[0]);
352 break;
353 }
354
355 if (status == 0)
356 status = count;
357 } else {
358 status = i2c_transfer(client->adapter, &msg, 1);
359 if (status == 1)
360 status = count;
361 }
362 dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n",
363 count, offset, status, jiffies);
364
365 if (status == count)
366 return count;
367
368 /* REVISIT: at HZ=100, this is sloooow */
369 msleep(1);
370 } while (time_before(write_time, timeout));
371
372 return -ETIMEDOUT;
373}
374
375static ssize_t at24_write(struct at24_data *at24, const char *buf, loff_t off,
376 size_t count)
377{
378 ssize_t retval = 0;
379
380 if (unlikely(!count))
381 return count;
382
383 /*
384 * Write data to chip, protecting against concurrent updates
385 * from this host, but not from other I2C masters.
386 */
387 mutex_lock(&at24->lock);
388
389 while (count) {
390 ssize_t status;
391
392 status = at24_eeprom_write(at24, buf, off, count);
393 if (status <= 0) {
394 if (retval == 0)
395 retval = status;
396 break;
397 }
398 buf += status;
399 off += status;
400 count -= status;
401 retval += status;
402 }
403
404 mutex_unlock(&at24->lock);
405
406 return retval;
407}
408
409/*-------------------------------------------------------------------------*/
410
411/*
412 * Provide a regmap interface, which is registered with the NVMEM
413 * framework
414*/
415static int at24_regmap_read(void *context, const void *reg, size_t reg_size,
416 void *val, size_t val_size)
417{
418 struct at24_data *at24 = context;
419 off_t offset = *(u32 *)reg;
420 int err;
421
422 err = at24_read(at24, val, offset, val_size);
423 if (err)
424 return err;
425 return 0;
426}
427
428static int at24_regmap_write(void *context, const void *data, size_t count)
429{
430 struct at24_data *at24 = context;
431 const char *buf;
432 u32 offset;
433 size_t len;
434 int err;
435
436 memcpy(&offset, data, sizeof(offset));
437 buf = (const char *)data + sizeof(offset);
438 len = count - sizeof(offset);
439
440 err = at24_write(at24, buf, offset, len);
441 if (err)
442 return err;
443 return 0;
444}
445
446static const struct regmap_bus at24_regmap_bus = {
447 .read = at24_regmap_read,
448 .write = at24_regmap_write,
449 .reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
450};
451
452/*-------------------------------------------------------------------------*/
453
454#ifdef CONFIG_OF
455static void at24_get_ofdata(struct i2c_client *client,
456 struct at24_platform_data *chip)
457{
458 const __be32 *val;
459 struct device_node *node = client->dev.of_node;
460
461 if (node) {
462 if (of_get_property(node, "read-only", NULL))
463 chip->flags |= AT24_FLAG_READONLY;
464 val = of_get_property(node, "pagesize", NULL);
465 if (val)
466 chip->page_size = be32_to_cpup(val);
467 }
468}
469#else
470static void at24_get_ofdata(struct i2c_client *client,
471 struct at24_platform_data *chip)
472{ }
473#endif /* CONFIG_OF */
474
475static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
476{
477 struct at24_platform_data chip;
478 kernel_ulong_t magic = 0;
479 bool writable;
480 int use_smbus = 0;
481 int use_smbus_write = 0;
482 struct at24_data *at24;
483 int err;
484 unsigned i, num_addresses;
485 struct regmap *regmap;
486
487 if (client->dev.platform_data) {
488 chip = *(struct at24_platform_data *)client->dev.platform_data;
489 } else {
490 if (id) {
491 magic = id->driver_data;
492 } else {
493 const struct acpi_device_id *aid;
494
495 aid = acpi_match_device(at24_acpi_ids, &client->dev);
496 if (aid)
497 magic = aid->driver_data;
498 }
499 if (!magic)
500 return -ENODEV;
501
502 chip.byte_len = BIT(magic & AT24_BITMASK(AT24_SIZE_BYTELEN));
503 magic >>= AT24_SIZE_BYTELEN;
504 chip.flags = magic & AT24_BITMASK(AT24_SIZE_FLAGS);
505 /*
506 * This is slow, but we can't know all eeproms, so we better
507 * play safe. Specifying custom eeprom-types via platform_data
508 * is recommended anyhow.
509 */
510 chip.page_size = 1;
511
512 /* update chipdata if OF is present */
513 at24_get_ofdata(client, &chip);
514
515 chip.setup = NULL;
516 chip.context = NULL;
517 }
518
519 if (!is_power_of_2(chip.byte_len))
520 dev_warn(&client->dev,
521 "byte_len looks suspicious (no power of 2)!\n");
522 if (!chip.page_size) {
523 dev_err(&client->dev, "page_size must not be 0!\n");
524 return -EINVAL;
525 }
526 if (!is_power_of_2(chip.page_size))
527 dev_warn(&client->dev,
528 "page_size looks suspicious (no power of 2)!\n");
529
530 /* Use I2C operations unless we're stuck with SMBus extensions. */
531 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
532 if (chip.flags & AT24_FLAG_ADDR16)
533 return -EPFNOSUPPORT;
534
535 if (i2c_check_functionality(client->adapter,
536 I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
537 use_smbus = I2C_SMBUS_I2C_BLOCK_DATA;
538 } else if (i2c_check_functionality(client->adapter,
539 I2C_FUNC_SMBUS_READ_WORD_DATA)) {
540 use_smbus = I2C_SMBUS_WORD_DATA;
541 } else if (i2c_check_functionality(client->adapter,
542 I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
543 use_smbus = I2C_SMBUS_BYTE_DATA;
544 } else {
545 return -EPFNOSUPPORT;
546 }
547 }
548
549 /* Use I2C operations unless we're stuck with SMBus extensions. */
550 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
551 if (i2c_check_functionality(client->adapter,
552 I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
553 use_smbus_write = I2C_SMBUS_I2C_BLOCK_DATA;
554 } else if (i2c_check_functionality(client->adapter,
555 I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) {
556 use_smbus_write = I2C_SMBUS_BYTE_DATA;
557 chip.page_size = 1;
558 }
559 }
560
561 if (chip.flags & AT24_FLAG_TAKE8ADDR)
562 num_addresses = 8;
563 else
564 num_addresses = DIV_ROUND_UP(chip.byte_len,
565 (chip.flags & AT24_FLAG_ADDR16) ? 65536 : 256);
566
567 at24 = devm_kzalloc(&client->dev, sizeof(struct at24_data) +
568 num_addresses * sizeof(struct i2c_client *), GFP_KERNEL);
569 if (!at24)
570 return -ENOMEM;
571
572 mutex_init(&at24->lock);
573 at24->use_smbus = use_smbus;
574 at24->use_smbus_write = use_smbus_write;
575 at24->chip = chip;
576 at24->num_addresses = num_addresses;
577
578 writable = !(chip.flags & AT24_FLAG_READONLY);
579 if (writable) {
580 if (!use_smbus || use_smbus_write) {
581
582 unsigned write_max = chip.page_size;
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 at24->regmap_config.reg_bits = 32;
616 at24->regmap_config.val_bits = 8;
617 at24->regmap_config.reg_stride = 1;
618 at24->regmap_config.max_register = chip.byte_len - 1;
619
620 regmap = devm_regmap_init(&client->dev, &at24_regmap_bus, at24,
621 &at24->regmap_config);
622 if (IS_ERR(regmap)) {
623 dev_err(&client->dev, "regmap init failed\n");
624 err = PTR_ERR(regmap);
625 goto err_clients;
626 }
627
628 at24->nvmem_config.name = dev_name(&client->dev);
629 at24->nvmem_config.dev = &client->dev;
630 at24->nvmem_config.read_only = !writable;
631 at24->nvmem_config.root_only = true;
632 at24->nvmem_config.owner = THIS_MODULE;
633 at24->nvmem_config.compat = true;
634 at24->nvmem_config.base_dev = &client->dev;
635
636 at24->nvmem = nvmem_register(&at24->nvmem_config);
637
638 if (IS_ERR(at24->nvmem)) {
639 err = PTR_ERR(at24->nvmem);
640 goto err_clients;
641 }
642
643 i2c_set_clientdata(client, at24);
644
645 dev_info(&client->dev, "%u byte %s EEPROM, %s, %u bytes/write\n",
646 chip.byte_len, client->name,
647 writable ? "writable" : "read-only", at24->write_max);
648 if (use_smbus == I2C_SMBUS_WORD_DATA ||
649 use_smbus == I2C_SMBUS_BYTE_DATA) {
650 dev_notice(&client->dev, "Falling back to %s reads, "
651 "performance will suffer\n", use_smbus ==
652 I2C_SMBUS_WORD_DATA ? "word" : "byte");
653 }
654
655 /* export data to kernel code */
656 if (chip.setup)
657 chip.setup(at24->nvmem, chip.context);
658
659 return 0;
660
661err_clients:
662 for (i = 1; i < num_addresses; i++)
663 if (at24->client[i])
664 i2c_unregister_device(at24->client[i]);
665
666 return err;
667}
668
669static int at24_remove(struct i2c_client *client)
670{
671 struct at24_data *at24;
672 int i;
673
674 at24 = i2c_get_clientdata(client);
675
676 nvmem_unregister(at24->nvmem);
677
678 for (i = 1; i < at24->num_addresses; i++)
679 i2c_unregister_device(at24->client[i]);
680
681 return 0;
682}
683
684/*-------------------------------------------------------------------------*/
685
686static struct i2c_driver at24_driver = {
687 .driver = {
688 .name = "at24",
689 .acpi_match_table = ACPI_PTR(at24_acpi_ids),
690 },
691 .probe = at24_probe,
692 .remove = at24_remove,
693 .id_table = at24_ids,
694};
695
696static int __init at24_init(void)
697{
698 if (!io_limit) {
699 pr_err("at24: io_limit must not be 0!\n");
700 return -EINVAL;
701 }
702
703 io_limit = rounddown_pow_of_two(io_limit);
704 return i2c_add_driver(&at24_driver);
705}
706module_init(at24_init);
707
708static void __exit at24_exit(void)
709{
710 i2c_del_driver(&at24_driver);
711}
712module_exit(at24_exit);
713
714MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
715MODULE_AUTHOR("David Brownell and Wolfram Sang");
716MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0-or-later
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/acpi.h>
10#include <linux/bitops.h>
11#include <linux/capability.h>
12#include <linux/delay.h>
13#include <linux/i2c.h>
14#include <linux/init.h>
15#include <linux/jiffies.h>
16#include <linux/kernel.h>
17#include <linux/mod_devicetable.h>
18#include <linux/module.h>
19#include <linux/mutex.h>
20#include <linux/nvmem-provider.h>
21#include <linux/of_device.h>
22#include <linux/pm_runtime.h>
23#include <linux/property.h>
24#include <linux/regmap.h>
25#include <linux/regulator/consumer.h>
26#include <linux/slab.h>
27
28/* Address pointer is 16 bit. */
29#define AT24_FLAG_ADDR16 BIT(7)
30/* sysfs-entry will be read-only. */
31#define AT24_FLAG_READONLY BIT(6)
32/* sysfs-entry will be world-readable. */
33#define AT24_FLAG_IRUGO BIT(5)
34/* Take always 8 addresses (24c00). */
35#define AT24_FLAG_TAKE8ADDR BIT(4)
36/* Factory-programmed serial number. */
37#define AT24_FLAG_SERIAL BIT(3)
38/* Factory-programmed mac address. */
39#define AT24_FLAG_MAC BIT(2)
40/* Does not auto-rollover reads to the next slave address. */
41#define AT24_FLAG_NO_RDROL BIT(1)
42
43/*
44 * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
45 * Differences between different vendor product lines (like Atmel AT24C or
46 * MicroChip 24LC, etc) won't much matter for typical read/write access.
47 * There are also I2C RAM chips, likewise interchangeable. One example
48 * would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
49 *
50 * However, misconfiguration can lose data. "Set 16-bit memory address"
51 * to a part with 8-bit addressing will overwrite data. Writing with too
52 * big a page size also loses data. And it's not safe to assume that the
53 * conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
54 * uses 0x51, for just one example.
55 *
56 * Accordingly, explicit board-specific configuration data should be used
57 * in almost all cases. (One partial exception is an SMBus used to access
58 * "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
59 *
60 * So this driver uses "new style" I2C driver binding, expecting to be
61 * told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
62 * similar kernel-resident tables; or, configuration data coming from
63 * a bootloader.
64 *
65 * Other than binding model, current differences from "eeprom" driver are
66 * that this one handles write access and isn't restricted to 24c02 devices.
67 * It also handles larger devices (32 kbit and up) with two-byte addresses,
68 * which won't work on pure SMBus systems.
69 */
70
71struct at24_client {
72 struct i2c_client *client;
73 struct regmap *regmap;
74};
75
76struct at24_data {
77 /*
78 * Lock protects against activities from other Linux tasks,
79 * but not from changes by other I2C masters.
80 */
81 struct mutex lock;
82
83 unsigned int write_max;
84 unsigned int num_addresses;
85 unsigned int offset_adj;
86
87 u32 byte_len;
88 u16 page_size;
89 u8 flags;
90
91 struct nvmem_device *nvmem;
92 struct regulator *vcc_reg;
93 void (*read_post)(unsigned int off, char *buf, size_t count);
94
95 /*
96 * Some chips tie up multiple I2C addresses; dummy devices reserve
97 * them for us, and we'll use them with SMBus calls.
98 */
99 struct at24_client client[];
100};
101
102/*
103 * This parameter is to help this driver avoid blocking other drivers out
104 * of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
105 * clock, one 256 byte read takes about 1/43 second which is excessive;
106 * but the 1/170 second it takes at 400 kHz may be quite reasonable; and
107 * at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
108 *
109 * This value is forced to be a power of two so that writes align on pages.
110 */
111static unsigned int at24_io_limit = 128;
112module_param_named(io_limit, at24_io_limit, uint, 0);
113MODULE_PARM_DESC(at24_io_limit, "Maximum bytes per I/O (default 128)");
114
115/*
116 * Specs often allow 5 msec for a page write, sometimes 20 msec;
117 * it's important to recover from write timeouts.
118 */
119static unsigned int at24_write_timeout = 25;
120module_param_named(write_timeout, at24_write_timeout, uint, 0);
121MODULE_PARM_DESC(at24_write_timeout, "Time (in ms) to try writes (default 25)");
122
123struct at24_chip_data {
124 u32 byte_len;
125 u8 flags;
126 void (*read_post)(unsigned int off, char *buf, size_t count);
127};
128
129#define AT24_CHIP_DATA(_name, _len, _flags) \
130 static const struct at24_chip_data _name = { \
131 .byte_len = _len, .flags = _flags, \
132 }
133
134#define AT24_CHIP_DATA_CB(_name, _len, _flags, _read_post) \
135 static const struct at24_chip_data _name = { \
136 .byte_len = _len, .flags = _flags, \
137 .read_post = _read_post, \
138 }
139
140static void at24_read_post_vaio(unsigned int off, char *buf, size_t count)
141{
142 int i;
143
144 if (capable(CAP_SYS_ADMIN))
145 return;
146
147 /*
148 * Hide VAIO private settings to regular users:
149 * - BIOS passwords: bytes 0x00 to 0x0f
150 * - UUID: bytes 0x10 to 0x1f
151 * - Serial number: 0xc0 to 0xdf
152 */
153 for (i = 0; i < count; i++) {
154 if ((off + i <= 0x1f) ||
155 (off + i >= 0xc0 && off + i <= 0xdf))
156 buf[i] = 0;
157 }
158}
159
160/* needs 8 addresses as A0-A2 are ignored */
161AT24_CHIP_DATA(at24_data_24c00, 128 / 8, AT24_FLAG_TAKE8ADDR);
162/* old variants can't be handled with this generic entry! */
163AT24_CHIP_DATA(at24_data_24c01, 1024 / 8, 0);
164AT24_CHIP_DATA(at24_data_24cs01, 16,
165 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
166AT24_CHIP_DATA(at24_data_24c02, 2048 / 8, 0);
167AT24_CHIP_DATA(at24_data_24cs02, 16,
168 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
169AT24_CHIP_DATA(at24_data_24mac402, 48 / 8,
170 AT24_FLAG_MAC | AT24_FLAG_READONLY);
171AT24_CHIP_DATA(at24_data_24mac602, 64 / 8,
172 AT24_FLAG_MAC | AT24_FLAG_READONLY);
173/* spd is a 24c02 in memory DIMMs */
174AT24_CHIP_DATA(at24_data_spd, 2048 / 8,
175 AT24_FLAG_READONLY | AT24_FLAG_IRUGO);
176/* 24c02_vaio is a 24c02 on some Sony laptops */
177AT24_CHIP_DATA_CB(at24_data_24c02_vaio, 2048 / 8,
178 AT24_FLAG_READONLY | AT24_FLAG_IRUGO,
179 at24_read_post_vaio);
180AT24_CHIP_DATA(at24_data_24c04, 4096 / 8, 0);
181AT24_CHIP_DATA(at24_data_24cs04, 16,
182 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
183/* 24rf08 quirk is handled at i2c-core */
184AT24_CHIP_DATA(at24_data_24c08, 8192 / 8, 0);
185AT24_CHIP_DATA(at24_data_24cs08, 16,
186 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
187AT24_CHIP_DATA(at24_data_24c16, 16384 / 8, 0);
188AT24_CHIP_DATA(at24_data_24cs16, 16,
189 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
190AT24_CHIP_DATA(at24_data_24c32, 32768 / 8, AT24_FLAG_ADDR16);
191AT24_CHIP_DATA(at24_data_24cs32, 16,
192 AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
193AT24_CHIP_DATA(at24_data_24c64, 65536 / 8, AT24_FLAG_ADDR16);
194AT24_CHIP_DATA(at24_data_24cs64, 16,
195 AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
196AT24_CHIP_DATA(at24_data_24c128, 131072 / 8, AT24_FLAG_ADDR16);
197AT24_CHIP_DATA(at24_data_24c256, 262144 / 8, AT24_FLAG_ADDR16);
198AT24_CHIP_DATA(at24_data_24c512, 524288 / 8, AT24_FLAG_ADDR16);
199AT24_CHIP_DATA(at24_data_24c1024, 1048576 / 8, AT24_FLAG_ADDR16);
200AT24_CHIP_DATA(at24_data_24c2048, 2097152 / 8, AT24_FLAG_ADDR16);
201/* identical to 24c08 ? */
202AT24_CHIP_DATA(at24_data_INT3499, 8192 / 8, 0);
203
204static const struct i2c_device_id at24_ids[] = {
205 { "24c00", (kernel_ulong_t)&at24_data_24c00 },
206 { "24c01", (kernel_ulong_t)&at24_data_24c01 },
207 { "24cs01", (kernel_ulong_t)&at24_data_24cs01 },
208 { "24c02", (kernel_ulong_t)&at24_data_24c02 },
209 { "24cs02", (kernel_ulong_t)&at24_data_24cs02 },
210 { "24mac402", (kernel_ulong_t)&at24_data_24mac402 },
211 { "24mac602", (kernel_ulong_t)&at24_data_24mac602 },
212 { "spd", (kernel_ulong_t)&at24_data_spd },
213 { "24c02-vaio", (kernel_ulong_t)&at24_data_24c02_vaio },
214 { "24c04", (kernel_ulong_t)&at24_data_24c04 },
215 { "24cs04", (kernel_ulong_t)&at24_data_24cs04 },
216 { "24c08", (kernel_ulong_t)&at24_data_24c08 },
217 { "24cs08", (kernel_ulong_t)&at24_data_24cs08 },
218 { "24c16", (kernel_ulong_t)&at24_data_24c16 },
219 { "24cs16", (kernel_ulong_t)&at24_data_24cs16 },
220 { "24c32", (kernel_ulong_t)&at24_data_24c32 },
221 { "24cs32", (kernel_ulong_t)&at24_data_24cs32 },
222 { "24c64", (kernel_ulong_t)&at24_data_24c64 },
223 { "24cs64", (kernel_ulong_t)&at24_data_24cs64 },
224 { "24c128", (kernel_ulong_t)&at24_data_24c128 },
225 { "24c256", (kernel_ulong_t)&at24_data_24c256 },
226 { "24c512", (kernel_ulong_t)&at24_data_24c512 },
227 { "24c1024", (kernel_ulong_t)&at24_data_24c1024 },
228 { "24c2048", (kernel_ulong_t)&at24_data_24c2048 },
229 { "at24", 0 },
230 { /* END OF LIST */ }
231};
232MODULE_DEVICE_TABLE(i2c, at24_ids);
233
234static const struct of_device_id at24_of_match[] = {
235 { .compatible = "atmel,24c00", .data = &at24_data_24c00 },
236 { .compatible = "atmel,24c01", .data = &at24_data_24c01 },
237 { .compatible = "atmel,24cs01", .data = &at24_data_24cs01 },
238 { .compatible = "atmel,24c02", .data = &at24_data_24c02 },
239 { .compatible = "atmel,24cs02", .data = &at24_data_24cs02 },
240 { .compatible = "atmel,24mac402", .data = &at24_data_24mac402 },
241 { .compatible = "atmel,24mac602", .data = &at24_data_24mac602 },
242 { .compatible = "atmel,spd", .data = &at24_data_spd },
243 { .compatible = "atmel,24c04", .data = &at24_data_24c04 },
244 { .compatible = "atmel,24cs04", .data = &at24_data_24cs04 },
245 { .compatible = "atmel,24c08", .data = &at24_data_24c08 },
246 { .compatible = "atmel,24cs08", .data = &at24_data_24cs08 },
247 { .compatible = "atmel,24c16", .data = &at24_data_24c16 },
248 { .compatible = "atmel,24cs16", .data = &at24_data_24cs16 },
249 { .compatible = "atmel,24c32", .data = &at24_data_24c32 },
250 { .compatible = "atmel,24cs32", .data = &at24_data_24cs32 },
251 { .compatible = "atmel,24c64", .data = &at24_data_24c64 },
252 { .compatible = "atmel,24cs64", .data = &at24_data_24cs64 },
253 { .compatible = "atmel,24c128", .data = &at24_data_24c128 },
254 { .compatible = "atmel,24c256", .data = &at24_data_24c256 },
255 { .compatible = "atmel,24c512", .data = &at24_data_24c512 },
256 { .compatible = "atmel,24c1024", .data = &at24_data_24c1024 },
257 { .compatible = "atmel,24c2048", .data = &at24_data_24c2048 },
258 { /* END OF LIST */ },
259};
260MODULE_DEVICE_TABLE(of, at24_of_match);
261
262static const struct acpi_device_id __maybe_unused at24_acpi_ids[] = {
263 { "INT3499", (kernel_ulong_t)&at24_data_INT3499 },
264 { "TPF0001", (kernel_ulong_t)&at24_data_24c1024 },
265 { /* END OF LIST */ }
266};
267MODULE_DEVICE_TABLE(acpi, at24_acpi_ids);
268
269/*
270 * This routine supports chips which consume multiple I2C addresses. It
271 * computes the addressing information to be used for a given r/w request.
272 * Assumes that sanity checks for offset happened at sysfs-layer.
273 *
274 * Slave address and byte offset derive from the offset. Always
275 * set the byte address; on a multi-master board, another master
276 * may have changed the chip's "current" address pointer.
277 */
278static struct at24_client *at24_translate_offset(struct at24_data *at24,
279 unsigned int *offset)
280{
281 unsigned int i;
282
283 if (at24->flags & AT24_FLAG_ADDR16) {
284 i = *offset >> 16;
285 *offset &= 0xffff;
286 } else {
287 i = *offset >> 8;
288 *offset &= 0xff;
289 }
290
291 return &at24->client[i];
292}
293
294static struct device *at24_base_client_dev(struct at24_data *at24)
295{
296 return &at24->client[0].client->dev;
297}
298
299static size_t at24_adjust_read_count(struct at24_data *at24,
300 unsigned int offset, size_t count)
301{
302 unsigned int bits;
303 size_t remainder;
304
305 /*
306 * In case of multi-address chips that don't rollover reads to
307 * the next slave address: truncate the count to the slave boundary,
308 * so that the read never straddles slaves.
309 */
310 if (at24->flags & AT24_FLAG_NO_RDROL) {
311 bits = (at24->flags & AT24_FLAG_ADDR16) ? 16 : 8;
312 remainder = BIT(bits) - offset;
313 if (count > remainder)
314 count = remainder;
315 }
316
317 if (count > at24_io_limit)
318 count = at24_io_limit;
319
320 return count;
321}
322
323static ssize_t at24_regmap_read(struct at24_data *at24, char *buf,
324 unsigned int offset, size_t count)
325{
326 unsigned long timeout, read_time;
327 struct at24_client *at24_client;
328 struct i2c_client *client;
329 struct regmap *regmap;
330 int ret;
331
332 at24_client = at24_translate_offset(at24, &offset);
333 regmap = at24_client->regmap;
334 client = at24_client->client;
335 count = at24_adjust_read_count(at24, offset, count);
336
337 /* adjust offset for mac and serial read ops */
338 offset += at24->offset_adj;
339
340 timeout = jiffies + msecs_to_jiffies(at24_write_timeout);
341 do {
342 /*
343 * The timestamp shall be taken before the actual operation
344 * to avoid a premature timeout in case of high CPU load.
345 */
346 read_time = jiffies;
347
348 ret = regmap_bulk_read(regmap, offset, buf, count);
349 dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
350 count, offset, ret, jiffies);
351 if (!ret)
352 return count;
353
354 usleep_range(1000, 1500);
355 } while (time_before(read_time, timeout));
356
357 return -ETIMEDOUT;
358}
359
360/*
361 * Note that if the hardware write-protect pin is pulled high, the whole
362 * chip is normally write protected. But there are plenty of product
363 * variants here, including OTP fuses and partial chip protect.
364 *
365 * We only use page mode writes; the alternative is sloooow. These routines
366 * write at most one page.
367 */
368
369static size_t at24_adjust_write_count(struct at24_data *at24,
370 unsigned int offset, size_t count)
371{
372 unsigned int next_page;
373
374 /* write_max is at most a page */
375 if (count > at24->write_max)
376 count = at24->write_max;
377
378 /* Never roll over backwards, to the start of this page */
379 next_page = roundup(offset + 1, at24->page_size);
380 if (offset + count > next_page)
381 count = next_page - offset;
382
383 return count;
384}
385
386static ssize_t at24_regmap_write(struct at24_data *at24, const char *buf,
387 unsigned int offset, size_t count)
388{
389 unsigned long timeout, write_time;
390 struct at24_client *at24_client;
391 struct i2c_client *client;
392 struct regmap *regmap;
393 int ret;
394
395 at24_client = at24_translate_offset(at24, &offset);
396 regmap = at24_client->regmap;
397 client = at24_client->client;
398 count = at24_adjust_write_count(at24, offset, count);
399 timeout = jiffies + msecs_to_jiffies(at24_write_timeout);
400
401 do {
402 /*
403 * The timestamp shall be taken before the actual operation
404 * to avoid a premature timeout in case of high CPU load.
405 */
406 write_time = jiffies;
407
408 ret = regmap_bulk_write(regmap, offset, buf, count);
409 dev_dbg(&client->dev, "write %zu@%d --> %d (%ld)\n",
410 count, offset, ret, jiffies);
411 if (!ret)
412 return count;
413
414 usleep_range(1000, 1500);
415 } while (time_before(write_time, timeout));
416
417 return -ETIMEDOUT;
418}
419
420static int at24_read(void *priv, unsigned int off, void *val, size_t count)
421{
422 struct at24_data *at24;
423 struct device *dev;
424 char *buf = val;
425 int i, ret;
426
427 at24 = priv;
428 dev = at24_base_client_dev(at24);
429
430 if (unlikely(!count))
431 return count;
432
433 if (off + count > at24->byte_len)
434 return -EINVAL;
435
436 ret = pm_runtime_get_sync(dev);
437 if (ret < 0) {
438 pm_runtime_put_noidle(dev);
439 return ret;
440 }
441
442 /*
443 * Read data from chip, protecting against concurrent updates
444 * from this host, but not from other I2C masters.
445 */
446 mutex_lock(&at24->lock);
447
448 for (i = 0; count; i += ret, count -= ret) {
449 ret = at24_regmap_read(at24, buf + i, off + i, count);
450 if (ret < 0) {
451 mutex_unlock(&at24->lock);
452 pm_runtime_put(dev);
453 return ret;
454 }
455 }
456
457 mutex_unlock(&at24->lock);
458
459 pm_runtime_put(dev);
460
461 if (unlikely(at24->read_post))
462 at24->read_post(off, buf, i);
463
464 return 0;
465}
466
467static int at24_write(void *priv, unsigned int off, void *val, size_t count)
468{
469 struct at24_data *at24;
470 struct device *dev;
471 char *buf = val;
472 int ret;
473
474 at24 = priv;
475 dev = at24_base_client_dev(at24);
476
477 if (unlikely(!count))
478 return -EINVAL;
479
480 if (off + count > at24->byte_len)
481 return -EINVAL;
482
483 ret = pm_runtime_get_sync(dev);
484 if (ret < 0) {
485 pm_runtime_put_noidle(dev);
486 return ret;
487 }
488
489 /*
490 * Write data to chip, protecting against concurrent updates
491 * from this host, but not from other I2C masters.
492 */
493 mutex_lock(&at24->lock);
494
495 while (count) {
496 ret = at24_regmap_write(at24, buf, off, count);
497 if (ret < 0) {
498 mutex_unlock(&at24->lock);
499 pm_runtime_put(dev);
500 return ret;
501 }
502 buf += ret;
503 off += ret;
504 count -= ret;
505 }
506
507 mutex_unlock(&at24->lock);
508
509 pm_runtime_put(dev);
510
511 return 0;
512}
513
514static const struct at24_chip_data *at24_get_chip_data(struct device *dev)
515{
516 struct device_node *of_node = dev->of_node;
517 const struct at24_chip_data *cdata;
518 const struct i2c_device_id *id;
519
520 id = i2c_match_id(at24_ids, to_i2c_client(dev));
521
522 /*
523 * The I2C core allows OF nodes compatibles to match against the
524 * I2C device ID table as a fallback, so check not only if an OF
525 * node is present but also if it matches an OF device ID entry.
526 */
527 if (of_node && of_match_device(at24_of_match, dev))
528 cdata = of_device_get_match_data(dev);
529 else if (id)
530 cdata = (void *)id->driver_data;
531 else
532 cdata = acpi_device_get_match_data(dev);
533
534 if (!cdata)
535 return ERR_PTR(-ENODEV);
536
537 return cdata;
538}
539
540static int at24_make_dummy_client(struct at24_data *at24, unsigned int index,
541 struct regmap_config *regmap_config)
542{
543 struct i2c_client *base_client, *dummy_client;
544 struct regmap *regmap;
545 struct device *dev;
546
547 base_client = at24->client[0].client;
548 dev = &base_client->dev;
549
550 dummy_client = devm_i2c_new_dummy_device(dev, base_client->adapter,
551 base_client->addr + index);
552 if (IS_ERR(dummy_client))
553 return PTR_ERR(dummy_client);
554
555 regmap = devm_regmap_init_i2c(dummy_client, regmap_config);
556 if (IS_ERR(regmap))
557 return PTR_ERR(regmap);
558
559 at24->client[index].client = dummy_client;
560 at24->client[index].regmap = regmap;
561
562 return 0;
563}
564
565static unsigned int at24_get_offset_adj(u8 flags, unsigned int byte_len)
566{
567 if (flags & AT24_FLAG_MAC) {
568 /* EUI-48 starts from 0x9a, EUI-64 from 0x98 */
569 return 0xa0 - byte_len;
570 } else if (flags & AT24_FLAG_SERIAL && flags & AT24_FLAG_ADDR16) {
571 /*
572 * For 16 bit address pointers, the word address must contain
573 * a '10' sequence in bits 11 and 10 regardless of the
574 * intended position of the address pointer.
575 */
576 return 0x0800;
577 } else if (flags & AT24_FLAG_SERIAL) {
578 /*
579 * Otherwise the word address must begin with a '10' sequence,
580 * regardless of the intended address.
581 */
582 return 0x0080;
583 } else {
584 return 0;
585 }
586}
587
588static int at24_probe(struct i2c_client *client)
589{
590 struct regmap_config regmap_config = { };
591 struct nvmem_config nvmem_config = { };
592 u32 byte_len, page_size, flags, addrw;
593 const struct at24_chip_data *cdata;
594 struct device *dev = &client->dev;
595 bool i2c_fn_i2c, i2c_fn_block;
596 unsigned int i, num_addresses;
597 struct at24_data *at24;
598 struct regmap *regmap;
599 bool writable;
600 u8 test_byte;
601 int err;
602
603 i2c_fn_i2c = i2c_check_functionality(client->adapter, I2C_FUNC_I2C);
604 i2c_fn_block = i2c_check_functionality(client->adapter,
605 I2C_FUNC_SMBUS_WRITE_I2C_BLOCK);
606
607 cdata = at24_get_chip_data(dev);
608 if (IS_ERR(cdata))
609 return PTR_ERR(cdata);
610
611 err = device_property_read_u32(dev, "pagesize", &page_size);
612 if (err)
613 /*
614 * This is slow, but we can't know all eeproms, so we better
615 * play safe. Specifying custom eeprom-types via device tree
616 * or properties is recommended anyhow.
617 */
618 page_size = 1;
619
620 flags = cdata->flags;
621 if (device_property_present(dev, "read-only"))
622 flags |= AT24_FLAG_READONLY;
623 if (device_property_present(dev, "no-read-rollover"))
624 flags |= AT24_FLAG_NO_RDROL;
625
626 err = device_property_read_u32(dev, "address-width", &addrw);
627 if (!err) {
628 switch (addrw) {
629 case 8:
630 if (flags & AT24_FLAG_ADDR16)
631 dev_warn(dev,
632 "Override address width to be 8, while default is 16\n");
633 flags &= ~AT24_FLAG_ADDR16;
634 break;
635 case 16:
636 flags |= AT24_FLAG_ADDR16;
637 break;
638 default:
639 dev_warn(dev, "Bad \"address-width\" property: %u\n",
640 addrw);
641 }
642 }
643
644 err = device_property_read_u32(dev, "size", &byte_len);
645 if (err)
646 byte_len = cdata->byte_len;
647
648 if (!i2c_fn_i2c && !i2c_fn_block)
649 page_size = 1;
650
651 if (!page_size) {
652 dev_err(dev, "page_size must not be 0!\n");
653 return -EINVAL;
654 }
655
656 if (!is_power_of_2(page_size))
657 dev_warn(dev, "page_size looks suspicious (no power of 2)!\n");
658
659 err = device_property_read_u32(dev, "num-addresses", &num_addresses);
660 if (err) {
661 if (flags & AT24_FLAG_TAKE8ADDR)
662 num_addresses = 8;
663 else
664 num_addresses = DIV_ROUND_UP(byte_len,
665 (flags & AT24_FLAG_ADDR16) ? 65536 : 256);
666 }
667
668 if ((flags & AT24_FLAG_SERIAL) && (flags & AT24_FLAG_MAC)) {
669 dev_err(dev,
670 "invalid device data - cannot have both AT24_FLAG_SERIAL & AT24_FLAG_MAC.");
671 return -EINVAL;
672 }
673
674 regmap_config.val_bits = 8;
675 regmap_config.reg_bits = (flags & AT24_FLAG_ADDR16) ? 16 : 8;
676 regmap_config.disable_locking = true;
677
678 regmap = devm_regmap_init_i2c(client, ®map_config);
679 if (IS_ERR(regmap))
680 return PTR_ERR(regmap);
681
682 at24 = devm_kzalloc(dev, struct_size(at24, client, num_addresses),
683 GFP_KERNEL);
684 if (!at24)
685 return -ENOMEM;
686
687 mutex_init(&at24->lock);
688 at24->byte_len = byte_len;
689 at24->page_size = page_size;
690 at24->flags = flags;
691 at24->read_post = cdata->read_post;
692 at24->num_addresses = num_addresses;
693 at24->offset_adj = at24_get_offset_adj(flags, byte_len);
694 at24->client[0].client = client;
695 at24->client[0].regmap = regmap;
696
697 at24->vcc_reg = devm_regulator_get(dev, "vcc");
698 if (IS_ERR(at24->vcc_reg))
699 return PTR_ERR(at24->vcc_reg);
700
701 writable = !(flags & AT24_FLAG_READONLY);
702 if (writable) {
703 at24->write_max = min_t(unsigned int,
704 page_size, at24_io_limit);
705 if (!i2c_fn_i2c && at24->write_max > I2C_SMBUS_BLOCK_MAX)
706 at24->write_max = I2C_SMBUS_BLOCK_MAX;
707 }
708
709 /* use dummy devices for multiple-address chips */
710 for (i = 1; i < num_addresses; i++) {
711 err = at24_make_dummy_client(at24, i, ®map_config);
712 if (err)
713 return err;
714 }
715
716 /*
717 * We initialize nvmem_config.id to NVMEM_DEVID_AUTO even if the
718 * label property is set as some platform can have multiple eeproms
719 * with same label and we can not register each of those with same
720 * label. Failing to register those eeproms trigger cascade failure
721 * on such platform.
722 */
723 nvmem_config.id = NVMEM_DEVID_AUTO;
724
725 if (device_property_present(dev, "label")) {
726 err = device_property_read_string(dev, "label",
727 &nvmem_config.name);
728 if (err)
729 return err;
730 } else {
731 nvmem_config.name = dev_name(dev);
732 }
733
734 nvmem_config.type = NVMEM_TYPE_EEPROM;
735 nvmem_config.dev = dev;
736 nvmem_config.read_only = !writable;
737 nvmem_config.root_only = !(flags & AT24_FLAG_IRUGO);
738 nvmem_config.owner = THIS_MODULE;
739 nvmem_config.compat = true;
740 nvmem_config.base_dev = dev;
741 nvmem_config.reg_read = at24_read;
742 nvmem_config.reg_write = at24_write;
743 nvmem_config.priv = at24;
744 nvmem_config.stride = 1;
745 nvmem_config.word_size = 1;
746 nvmem_config.size = byte_len;
747
748 i2c_set_clientdata(client, at24);
749
750 err = regulator_enable(at24->vcc_reg);
751 if (err) {
752 dev_err(dev, "Failed to enable vcc regulator\n");
753 return err;
754 }
755
756 /* enable runtime pm */
757 pm_runtime_set_active(dev);
758 pm_runtime_enable(dev);
759
760 at24->nvmem = devm_nvmem_register(dev, &nvmem_config);
761 if (IS_ERR(at24->nvmem)) {
762 pm_runtime_disable(dev);
763 if (!pm_runtime_status_suspended(dev))
764 regulator_disable(at24->vcc_reg);
765 return PTR_ERR(at24->nvmem);
766 }
767
768 /*
769 * Perform a one-byte test read to verify that the
770 * chip is functional.
771 */
772 err = at24_read(at24, 0, &test_byte, 1);
773 if (err) {
774 pm_runtime_disable(dev);
775 if (!pm_runtime_status_suspended(dev))
776 regulator_disable(at24->vcc_reg);
777 return -ENODEV;
778 }
779
780 pm_runtime_idle(dev);
781
782 if (writable)
783 dev_info(dev, "%u byte %s EEPROM, writable, %u bytes/write\n",
784 byte_len, client->name, at24->write_max);
785 else
786 dev_info(dev, "%u byte %s EEPROM, read-only\n",
787 byte_len, client->name);
788
789 return 0;
790}
791
792static int at24_remove(struct i2c_client *client)
793{
794 struct at24_data *at24 = i2c_get_clientdata(client);
795
796 pm_runtime_disable(&client->dev);
797 if (!pm_runtime_status_suspended(&client->dev))
798 regulator_disable(at24->vcc_reg);
799 pm_runtime_set_suspended(&client->dev);
800
801 return 0;
802}
803
804static int __maybe_unused at24_suspend(struct device *dev)
805{
806 struct i2c_client *client = to_i2c_client(dev);
807 struct at24_data *at24 = i2c_get_clientdata(client);
808
809 return regulator_disable(at24->vcc_reg);
810}
811
812static int __maybe_unused at24_resume(struct device *dev)
813{
814 struct i2c_client *client = to_i2c_client(dev);
815 struct at24_data *at24 = i2c_get_clientdata(client);
816
817 return regulator_enable(at24->vcc_reg);
818}
819
820static const struct dev_pm_ops at24_pm_ops = {
821 SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
822 pm_runtime_force_resume)
823 SET_RUNTIME_PM_OPS(at24_suspend, at24_resume, NULL)
824};
825
826static struct i2c_driver at24_driver = {
827 .driver = {
828 .name = "at24",
829 .pm = &at24_pm_ops,
830 .of_match_table = at24_of_match,
831 .acpi_match_table = ACPI_PTR(at24_acpi_ids),
832 },
833 .probe_new = at24_probe,
834 .remove = at24_remove,
835 .id_table = at24_ids,
836};
837
838static int __init at24_init(void)
839{
840 if (!at24_io_limit) {
841 pr_err("at24: at24_io_limit must not be 0!\n");
842 return -EINVAL;
843 }
844
845 at24_io_limit = rounddown_pow_of_two(at24_io_limit);
846 return i2c_add_driver(&at24_driver);
847}
848module_init(at24_init);
849
850static void __exit at24_exit(void)
851{
852 i2c_del_driver(&at24_driver);
853}
854module_exit(at24_exit);
855
856MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
857MODULE_AUTHOR("David Brownell and Wolfram Sang");
858MODULE_LICENSE("GPL");