blob: 2d3db81be0990a1b88109aa7614f74f201930204 [file] [log] [blame]
Wolfram Sang2b7a5052008-07-14 22:38:35 +02001/*
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/sysfs.h>
19#include <linux/mod_devicetable.h>
20#include <linux/log2.h>
21#include <linux/bitops.h>
22#include <linux/jiffies.h>
Wolfram Sang9ed030d2010-11-17 13:00:48 +010023#include <linux/of.h>
Wolfram Sang2b7a5052008-07-14 22:38:35 +020024#include <linux/i2c.h>
Vivien Didelot25f73ed2013-09-27 15:06:28 -040025#include <linux/platform_data/at24.h>
Wolfram Sang2b7a5052008-07-14 22:38:35 +020026
27/*
28 * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
29 * Differences between different vendor product lines (like Atmel AT24C or
30 * MicroChip 24LC, etc) won't much matter for typical read/write access.
31 * There are also I2C RAM chips, likewise interchangeable. One example
32 * would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
33 *
34 * However, misconfiguration can lose data. "Set 16-bit memory address"
35 * to a part with 8-bit addressing will overwrite data. Writing with too
36 * big a page size also loses data. And it's not safe to assume that the
37 * conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
38 * uses 0x51, for just one example.
39 *
40 * Accordingly, explicit board-specific configuration data should be used
41 * in almost all cases. (One partial exception is an SMBus used to access
42 * "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
43 *
44 * So this driver uses "new style" I2C driver binding, expecting to be
45 * told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
46 * similar kernel-resident tables; or, configuration data coming from
47 * a bootloader.
48 *
49 * Other than binding model, current differences from "eeprom" driver are
50 * that this one handles write access and isn't restricted to 24c02 devices.
51 * It also handles larger devices (32 kbit and up) with two-byte addresses,
52 * which won't work on pure SMBus systems.
53 */
54
55struct at24_data {
56 struct at24_platform_data chip;
Kevin Hilman7274ec82009-04-02 16:56:57 -070057 struct memory_accessor macc;
Jean Delvare7aeb9662010-05-21 18:40:57 +020058 int use_smbus;
Christian Gmeinera839ce62014-10-09 11:07:58 +020059 int use_smbus_write;
Wolfram Sang2b7a5052008-07-14 22:38:35 +020060
61 /*
62 * Lock protects against activities from other Linux tasks,
63 * but not from changes by other I2C masters.
64 */
65 struct mutex lock;
66 struct bin_attribute bin;
67
68 u8 *writebuf;
69 unsigned write_max;
70 unsigned num_addresses;
71
72 /*
73 * Some chips tie up multiple I2C addresses; dummy devices reserve
74 * them for us, and we'll use them with SMBus calls.
75 */
76 struct i2c_client *client[];
77};
78
79/*
80 * This parameter is to help this driver avoid blocking other drivers out
81 * of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
82 * clock, one 256 byte read takes about 1/43 second which is excessive;
83 * but the 1/170 second it takes at 400 kHz may be quite reasonable; and
84 * at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
85 *
86 * This value is forced to be a power of two so that writes align on pages.
87 */
88static unsigned io_limit = 128;
89module_param(io_limit, uint, 0);
90MODULE_PARM_DESC(io_limit, "Maximum bytes per I/O (default 128)");
91
92/*
93 * Specs often allow 5 msec for a page write, sometimes 20 msec;
94 * it's important to recover from write timeouts.
95 */
96static unsigned write_timeout = 25;
97module_param(write_timeout, uint, 0);
98MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
99
100#define AT24_SIZE_BYTELEN 5
101#define AT24_SIZE_FLAGS 8
102
103#define AT24_BITMASK(x) (BIT(x) - 1)
104
105/* create non-zero magic value for given eeprom parameters */
106#define AT24_DEVICE_MAGIC(_len, _flags) \
107 ((1 << AT24_SIZE_FLAGS | (_flags)) \
108 << AT24_SIZE_BYTELEN | ilog2(_len))
109
110static const struct i2c_device_id at24_ids[] = {
111 /* needs 8 addresses as A0-A2 are ignored */
112 { "24c00", AT24_DEVICE_MAGIC(128 / 8, AT24_FLAG_TAKE8ADDR) },
113 /* old variants can't be handled with this generic entry! */
114 { "24c01", AT24_DEVICE_MAGIC(1024 / 8, 0) },
115 { "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) },
116 /* spd is a 24c02 in memory DIMMs */
117 { "spd", AT24_DEVICE_MAGIC(2048 / 8,
118 AT24_FLAG_READONLY | AT24_FLAG_IRUGO) },
119 { "24c04", AT24_DEVICE_MAGIC(4096 / 8, 0) },
120 /* 24rf08 quirk is handled at i2c-core */
121 { "24c08", AT24_DEVICE_MAGIC(8192 / 8, 0) },
122 { "24c16", AT24_DEVICE_MAGIC(16384 / 8, 0) },
123 { "24c32", AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16) },
124 { "24c64", AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16) },
125 { "24c128", AT24_DEVICE_MAGIC(131072 / 8, AT24_FLAG_ADDR16) },
126 { "24c256", AT24_DEVICE_MAGIC(262144 / 8, AT24_FLAG_ADDR16) },
127 { "24c512", AT24_DEVICE_MAGIC(524288 / 8, AT24_FLAG_ADDR16) },
128 { "24c1024", AT24_DEVICE_MAGIC(1048576 / 8, AT24_FLAG_ADDR16) },
129 { "at24", 0 },
130 { /* END OF LIST */ }
131};
132MODULE_DEVICE_TABLE(i2c, at24_ids);
133
134/*-------------------------------------------------------------------------*/
135
136/*
137 * This routine supports chips which consume multiple I2C addresses. It
138 * computes the addressing information to be used for a given r/w request.
139 * Assumes that sanity checks for offset happened at sysfs-layer.
140 */
141static struct i2c_client *at24_translate_offset(struct at24_data *at24,
142 unsigned *offset)
143{
144 unsigned i;
145
146 if (at24->chip.flags & AT24_FLAG_ADDR16) {
147 i = *offset >> 16;
148 *offset &= 0xffff;
149 } else {
150 i = *offset >> 8;
151 *offset &= 0xff;
152 }
153
154 return at24->client[i];
155}
156
157static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,
158 unsigned offset, size_t count)
159{
160 struct i2c_msg msg[2];
161 u8 msgbuf[2];
162 struct i2c_client *client;
Wolfram Sang4d291962009-11-26 09:22:33 +0100163 unsigned long timeout, read_time;
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200164 int status, i;
165
166 memset(msg, 0, sizeof(msg));
167
168 /*
169 * REVISIT some multi-address chips don't rollover page reads to
170 * the next slave address, so we may need to truncate the count.
171 * Those chips might need another quirk flag.
172 *
173 * If the real hardware used four adjacent 24c02 chips and that
174 * were misconfigured as one 24c08, that would be a similar effect:
175 * one "eeprom" file not four, but larger reads would fail when
176 * they crossed certain pages.
177 */
178
179 /*
180 * Slave address and byte offset derive from the offset. Always
181 * set the byte address; on a multi-master board, another master
182 * may have changed the chip's "current" address pointer.
183 */
184 client = at24_translate_offset(at24, &offset);
185
186 if (count > io_limit)
187 count = io_limit;
188
Jean Delvare7aeb9662010-05-21 18:40:57 +0200189 switch (at24->use_smbus) {
190 case I2C_SMBUS_I2C_BLOCK_DATA:
Wolfram Sang4d291962009-11-26 09:22:33 +0100191 /* Smaller eeproms can work given some SMBus extension calls */
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200192 if (count > I2C_SMBUS_BLOCK_MAX)
193 count = I2C_SMBUS_BLOCK_MAX;
Jean Delvare7aeb9662010-05-21 18:40:57 +0200194 break;
195 case I2C_SMBUS_WORD_DATA:
196 count = 2;
197 break;
198 case I2C_SMBUS_BYTE_DATA:
199 count = 1;
200 break;
201 default:
Wolfram Sang4d291962009-11-26 09:22:33 +0100202 /*
203 * When we have a better choice than SMBus calls, use a
204 * combined I2C message. Write address; then read up to
205 * io_limit data bytes. Note that read page rollover helps us
206 * here (unlike writes). msgbuf is u8 and will cast to our
207 * needs.
208 */
209 i = 0;
210 if (at24->chip.flags & AT24_FLAG_ADDR16)
211 msgbuf[i++] = offset >> 8;
212 msgbuf[i++] = offset;
213
214 msg[0].addr = client->addr;
215 msg[0].buf = msgbuf;
216 msg[0].len = i;
217
218 msg[1].addr = client->addr;
219 msg[1].flags = I2C_M_RD;
220 msg[1].buf = buf;
221 msg[1].len = count;
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200222 }
223
224 /*
Wolfram Sang4d291962009-11-26 09:22:33 +0100225 * Reads fail if the previous write didn't complete yet. We may
226 * loop a few times until this one succeeds, waiting at least
227 * long enough for one entire page write to work.
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200228 */
Wolfram Sang4d291962009-11-26 09:22:33 +0100229 timeout = jiffies + msecs_to_jiffies(write_timeout);
230 do {
231 read_time = jiffies;
Jean Delvare7aeb9662010-05-21 18:40:57 +0200232 switch (at24->use_smbus) {
233 case I2C_SMBUS_I2C_BLOCK_DATA:
Wolfram Sang4d291962009-11-26 09:22:33 +0100234 status = i2c_smbus_read_i2c_block_data(client, offset,
235 count, buf);
Jean Delvare7aeb9662010-05-21 18:40:57 +0200236 break;
237 case I2C_SMBUS_WORD_DATA:
238 status = i2c_smbus_read_word_data(client, offset);
239 if (status >= 0) {
240 buf[0] = status & 0xff;
241 buf[1] = status >> 8;
242 status = count;
243 }
244 break;
245 case I2C_SMBUS_BYTE_DATA:
246 status = i2c_smbus_read_byte_data(client, offset);
247 if (status >= 0) {
248 buf[0] = status;
249 status = count;
250 }
251 break;
252 default:
Wolfram Sang4d291962009-11-26 09:22:33 +0100253 status = i2c_transfer(client->adapter, msg, 2);
254 if (status == 2)
255 status = count;
256 }
257 dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
258 count, offset, status, jiffies);
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200259
Wolfram Sang4d291962009-11-26 09:22:33 +0100260 if (status == count)
261 return count;
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200262
Wolfram Sang4d291962009-11-26 09:22:33 +0100263 /* REVISIT: at HZ=100, this is sloooow */
264 msleep(1);
265 } while (time_before(read_time, timeout));
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200266
Wolfram Sang4d291962009-11-26 09:22:33 +0100267 return -ETIMEDOUT;
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200268}
269
Kevin Hilman7274ec82009-04-02 16:56:57 -0700270static ssize_t at24_read(struct at24_data *at24,
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200271 char *buf, loff_t off, size_t count)
272{
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200273 ssize_t retval = 0;
274
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200275 if (unlikely(!count))
276 return count;
277
278 /*
279 * Read data from chip, protecting against concurrent updates
280 * from this host, but not from other I2C masters.
281 */
282 mutex_lock(&at24->lock);
283
284 while (count) {
285 ssize_t status;
286
287 status = at24_eeprom_read(at24, buf, off, count);
288 if (status <= 0) {
289 if (retval == 0)
290 retval = status;
291 break;
292 }
293 buf += status;
294 off += status;
295 count -= status;
296 retval += status;
297 }
298
299 mutex_unlock(&at24->lock);
300
301 return retval;
302}
303
Chris Wright2c3c8be2010-05-12 18:28:57 -0700304static ssize_t at24_bin_read(struct file *filp, struct kobject *kobj,
305 struct bin_attribute *attr,
Kevin Hilman7274ec82009-04-02 16:56:57 -0700306 char *buf, loff_t off, size_t count)
307{
308 struct at24_data *at24;
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200309
Kevin Hilman7274ec82009-04-02 16:56:57 -0700310 at24 = dev_get_drvdata(container_of(kobj, struct device, kobj));
311 return at24_read(at24, buf, off, count);
312}
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200313
314
315/*
316 * Note that if the hardware write-protect pin is pulled high, the whole
317 * chip is normally write protected. But there are plenty of product
318 * variants here, including OTP fuses and partial chip protect.
319 *
320 * We only use page mode writes; the alternative is sloooow. This routine
321 * writes at most one page.
322 */
Geert Uytterhoeven280ca292009-04-13 14:40:06 -0700323static ssize_t at24_eeprom_write(struct at24_data *at24, const char *buf,
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200324 unsigned offset, size_t count)
325{
326 struct i2c_client *client;
327 struct i2c_msg msg;
Christian Gmeinera839ce62014-10-09 11:07:58 +0200328 ssize_t status = 0;
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200329 unsigned long timeout, write_time;
330 unsigned next_page;
331
332 /* Get corresponding I2C address and adjust offset */
333 client = at24_translate_offset(at24, &offset);
334
335 /* write_max is at most a page */
336 if (count > at24->write_max)
337 count = at24->write_max;
338
339 /* Never roll over backwards, to the start of this page */
340 next_page = roundup(offset + 1, at24->chip.page_size);
341 if (offset + count > next_page)
342 count = next_page - offset;
343
344 /* If we'll use I2C calls for I/O, set up the message */
345 if (!at24->use_smbus) {
346 int i = 0;
347
348 msg.addr = client->addr;
349 msg.flags = 0;
350
351 /* msg.buf is u8 and casts will mask the values */
352 msg.buf = at24->writebuf;
353 if (at24->chip.flags & AT24_FLAG_ADDR16)
354 msg.buf[i++] = offset >> 8;
355
356 msg.buf[i++] = offset;
357 memcpy(&msg.buf[i], buf, count);
358 msg.len = i + count;
359 }
360
361 /*
362 * Writes fail if the previous one didn't complete yet. We may
363 * loop a few times until this one succeeds, waiting at least
364 * long enough for one entire page write to work.
365 */
366 timeout = jiffies + msecs_to_jiffies(write_timeout);
367 do {
368 write_time = jiffies;
Christian Gmeinera839ce62014-10-09 11:07:58 +0200369 if (at24->use_smbus_write) {
370 switch (at24->use_smbus_write) {
371 case I2C_SMBUS_I2C_BLOCK_DATA:
372 status = i2c_smbus_write_i2c_block_data(client,
373 offset, count, buf);
374 break;
375 case I2C_SMBUS_BYTE_DATA:
376 status = i2c_smbus_write_byte_data(client,
377 offset, buf[0]);
378 break;
379 }
380
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200381 if (status == 0)
382 status = count;
383 } else {
384 status = i2c_transfer(client->adapter, &msg, 1);
385 if (status == 1)
386 status = count;
387 }
David Brownell2ce5b342008-08-10 22:56:16 +0200388 dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n",
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200389 count, offset, status, jiffies);
390
391 if (status == count)
392 return count;
393
394 /* REVISIT: at HZ=100, this is sloooow */
395 msleep(1);
396 } while (time_before(write_time, timeout));
397
398 return -ETIMEDOUT;
399}
400
Geert Uytterhoeven280ca292009-04-13 14:40:06 -0700401static ssize_t at24_write(struct at24_data *at24, const char *buf, loff_t off,
402 size_t count)
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200403{
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200404 ssize_t retval = 0;
405
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200406 if (unlikely(!count))
407 return count;
408
409 /*
410 * Write data to chip, protecting against concurrent updates
411 * from this host, but not from other I2C masters.
412 */
413 mutex_lock(&at24->lock);
414
415 while (count) {
416 ssize_t status;
417
418 status = at24_eeprom_write(at24, buf, off, count);
419 if (status <= 0) {
420 if (retval == 0)
421 retval = status;
422 break;
423 }
424 buf += status;
425 off += status;
426 count -= status;
427 retval += status;
428 }
429
430 mutex_unlock(&at24->lock);
431
432 return retval;
433}
434
Chris Wright2c3c8be2010-05-12 18:28:57 -0700435static ssize_t at24_bin_write(struct file *filp, struct kobject *kobj,
436 struct bin_attribute *attr,
Kevin Hilman7274ec82009-04-02 16:56:57 -0700437 char *buf, loff_t off, size_t count)
438{
439 struct at24_data *at24;
440
Vladimir Zapolskiy7c65e292013-10-28 19:05:15 +0200441 if (unlikely(off >= attr->size))
442 return -EFBIG;
443
Kevin Hilman7274ec82009-04-02 16:56:57 -0700444 at24 = dev_get_drvdata(container_of(kobj, struct device, kobj));
445 return at24_write(at24, buf, off, count);
446}
447
448/*-------------------------------------------------------------------------*/
449
450/*
451 * This lets other kernel code access the eeprom data. For example, it
452 * might hold a board's Ethernet address, or board-specific calibration
453 * data generated on the manufacturing floor.
454 */
455
456static ssize_t at24_macc_read(struct memory_accessor *macc, char *buf,
457 off_t offset, size_t count)
458{
459 struct at24_data *at24 = container_of(macc, struct at24_data, macc);
460
461 return at24_read(at24, buf, offset, count);
462}
463
Geert Uytterhoeven280ca292009-04-13 14:40:06 -0700464static ssize_t at24_macc_write(struct memory_accessor *macc, const char *buf,
Kevin Hilman7274ec82009-04-02 16:56:57 -0700465 off_t offset, size_t count)
466{
467 struct at24_data *at24 = container_of(macc, struct at24_data, macc);
468
469 return at24_write(at24, buf, offset, count);
470}
471
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200472/*-------------------------------------------------------------------------*/
473
Wolfram Sang9ed030d2010-11-17 13:00:48 +0100474#ifdef CONFIG_OF
475static void at24_get_ofdata(struct i2c_client *client,
476 struct at24_platform_data *chip)
477{
478 const __be32 *val;
479 struct device_node *node = client->dev.of_node;
480
481 if (node) {
482 if (of_get_property(node, "read-only", NULL))
483 chip->flags |= AT24_FLAG_READONLY;
484 val = of_get_property(node, "pagesize", NULL);
485 if (val)
486 chip->page_size = be32_to_cpup(val);
487 }
488}
489#else
490static void at24_get_ofdata(struct i2c_client *client,
491 struct at24_platform_data *chip)
492{ }
493#endif /* CONFIG_OF */
494
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200495static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
496{
497 struct at24_platform_data chip;
498 bool writable;
Jean Delvare7aeb9662010-05-21 18:40:57 +0200499 int use_smbus = 0;
Christian Gmeinera839ce62014-10-09 11:07:58 +0200500 int use_smbus_write = 0;
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200501 struct at24_data *at24;
502 int err;
503 unsigned i, num_addresses;
504 kernel_ulong_t magic;
505
506 if (client->dev.platform_data) {
507 chip = *(struct at24_platform_data *)client->dev.platform_data;
508 } else {
Nikolay Balandinf0ac2362013-05-28 13:00:20 -0700509 if (!id->driver_data)
510 return -ENODEV;
511
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200512 magic = id->driver_data;
513 chip.byte_len = BIT(magic & AT24_BITMASK(AT24_SIZE_BYTELEN));
514 magic >>= AT24_SIZE_BYTELEN;
515 chip.flags = magic & AT24_BITMASK(AT24_SIZE_FLAGS);
516 /*
517 * This is slow, but we can't know all eeproms, so we better
518 * play safe. Specifying custom eeprom-types via platform_data
519 * is recommended anyhow.
520 */
521 chip.page_size = 1;
Kevin Hilman7274ec82009-04-02 16:56:57 -0700522
Wolfram Sang9ed030d2010-11-17 13:00:48 +0100523 /* update chipdata if OF is present */
524 at24_get_ofdata(client, &chip);
525
Kevin Hilman7274ec82009-04-02 16:56:57 -0700526 chip.setup = NULL;
527 chip.context = NULL;
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200528 }
529
530 if (!is_power_of_2(chip.byte_len))
531 dev_warn(&client->dev,
532 "byte_len looks suspicious (no power of 2)!\n");
Wolfram Sang45efe842010-11-17 13:00:49 +0100533 if (!chip.page_size) {
534 dev_err(&client->dev, "page_size must not be 0!\n");
Nikolay Balandinf0ac2362013-05-28 13:00:20 -0700535 return -EINVAL;
Wolfram Sang45efe842010-11-17 13:00:49 +0100536 }
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200537 if (!is_power_of_2(chip.page_size))
538 dev_warn(&client->dev,
539 "page_size looks suspicious (no power of 2)!\n");
540
541 /* Use I2C operations unless we're stuck with SMBus extensions. */
542 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
Nikolay Balandinf0ac2362013-05-28 13:00:20 -0700543 if (chip.flags & AT24_FLAG_ADDR16)
544 return -EPFNOSUPPORT;
545
Jean Delvare7aeb9662010-05-21 18:40:57 +0200546 if (i2c_check_functionality(client->adapter,
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200547 I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
Jean Delvare7aeb9662010-05-21 18:40:57 +0200548 use_smbus = I2C_SMBUS_I2C_BLOCK_DATA;
549 } else if (i2c_check_functionality(client->adapter,
550 I2C_FUNC_SMBUS_READ_WORD_DATA)) {
551 use_smbus = I2C_SMBUS_WORD_DATA;
552 } else if (i2c_check_functionality(client->adapter,
553 I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
554 use_smbus = I2C_SMBUS_BYTE_DATA;
555 } else {
Nikolay Balandinf0ac2362013-05-28 13:00:20 -0700556 return -EPFNOSUPPORT;
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200557 }
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200558 }
559
Christian Gmeinera839ce62014-10-09 11:07:58 +0200560 /* Use I2C operations unless we're stuck with SMBus extensions. */
561 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
562 if (i2c_check_functionality(client->adapter,
563 I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
564 use_smbus_write = I2C_SMBUS_I2C_BLOCK_DATA;
565 } else if (i2c_check_functionality(client->adapter,
566 I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) {
567 use_smbus_write = I2C_SMBUS_BYTE_DATA;
568 chip.page_size = 1;
569 }
570 }
571
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200572 if (chip.flags & AT24_FLAG_TAKE8ADDR)
573 num_addresses = 8;
574 else
575 num_addresses = DIV_ROUND_UP(chip.byte_len,
576 (chip.flags & AT24_FLAG_ADDR16) ? 65536 : 256);
577
Nikolay Balandinf0ac2362013-05-28 13:00:20 -0700578 at24 = devm_kzalloc(&client->dev, sizeof(struct at24_data) +
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200579 num_addresses * sizeof(struct i2c_client *), GFP_KERNEL);
Nikolay Balandinf0ac2362013-05-28 13:00:20 -0700580 if (!at24)
581 return -ENOMEM;
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200582
583 mutex_init(&at24->lock);
584 at24->use_smbus = use_smbus;
Christian Gmeinera839ce62014-10-09 11:07:58 +0200585 at24->use_smbus_write = use_smbus_write;
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200586 at24->chip = chip;
587 at24->num_addresses = num_addresses;
588
589 /*
590 * Export the EEPROM bytes through sysfs, since that's convenient.
591 * By default, only root should see the data (maybe passwords etc)
592 */
Wolfram Sangd07b56b2010-03-13 20:56:55 +0100593 sysfs_bin_attr_init(&at24->bin);
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200594 at24->bin.attr.name = "eeprom";
595 at24->bin.attr.mode = chip.flags & AT24_FLAG_IRUGO ? S_IRUGO : S_IRUSR;
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200596 at24->bin.read = at24_bin_read;
597 at24->bin.size = chip.byte_len;
598
Kevin Hilman7274ec82009-04-02 16:56:57 -0700599 at24->macc.read = at24_macc_read;
600
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200601 writable = !(chip.flags & AT24_FLAG_READONLY);
602 if (writable) {
Christian Gmeinera839ce62014-10-09 11:07:58 +0200603 if (!use_smbus || use_smbus_write) {
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200604
605 unsigned write_max = chip.page_size;
606
Kevin Hilman7274ec82009-04-02 16:56:57 -0700607 at24->macc.write = at24_macc_write;
608
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200609 at24->bin.write = at24_bin_write;
610 at24->bin.attr.mode |= S_IWUSR;
611
612 if (write_max > io_limit)
613 write_max = io_limit;
614 if (use_smbus && write_max > I2C_SMBUS_BLOCK_MAX)
615 write_max = I2C_SMBUS_BLOCK_MAX;
616 at24->write_max = write_max;
617
618 /* buffer (data + address at the beginning) */
Nikolay Balandinf0ac2362013-05-28 13:00:20 -0700619 at24->writebuf = devm_kzalloc(&client->dev,
620 write_max + 2, GFP_KERNEL);
621 if (!at24->writebuf)
622 return -ENOMEM;
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200623 } else {
624 dev_warn(&client->dev,
625 "cannot write due to controller restrictions.");
626 }
627 }
628
629 at24->client[0] = client;
630
631 /* use dummy devices for multiple-address chips */
632 for (i = 1; i < num_addresses; i++) {
633 at24->client[i] = i2c_new_dummy(client->adapter,
634 client->addr + i);
635 if (!at24->client[i]) {
636 dev_err(&client->dev, "address 0x%02x unavailable\n",
637 client->addr + i);
638 err = -EADDRINUSE;
639 goto err_clients;
640 }
641 }
642
643 err = sysfs_create_bin_file(&client->dev.kobj, &at24->bin);
644 if (err)
645 goto err_clients;
646
647 i2c_set_clientdata(client, at24);
648
Wolfram Sang9ed030d2010-11-17 13:00:48 +0100649 dev_info(&client->dev, "%zu byte %s EEPROM, %s, %u bytes/write\n",
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200650 at24->bin.size, client->name,
Wolfram Sang9ed030d2010-11-17 13:00:48 +0100651 writable ? "writable" : "read-only", at24->write_max);
Jean Delvare7aeb9662010-05-21 18:40:57 +0200652 if (use_smbus == I2C_SMBUS_WORD_DATA ||
653 use_smbus == I2C_SMBUS_BYTE_DATA) {
654 dev_notice(&client->dev, "Falling back to %s reads, "
655 "performance will suffer\n", use_smbus ==
656 I2C_SMBUS_WORD_DATA ? "word" : "byte");
657 }
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200658
Kevin Hilman7274ec82009-04-02 16:56:57 -0700659 /* export data to kernel code */
660 if (chip.setup)
661 chip.setup(&at24->macc, chip.context);
662
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200663 return 0;
664
665err_clients:
666 for (i = 1; i < num_addresses; i++)
667 if (at24->client[i])
668 i2c_unregister_device(at24->client[i]);
669
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200670 return err;
671}
672
Bill Pemberton486a5c22012-11-19 13:26:02 -0500673static int at24_remove(struct i2c_client *client)
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200674{
675 struct at24_data *at24;
676 int i;
677
678 at24 = i2c_get_clientdata(client);
679 sysfs_remove_bin_file(&client->dev.kobj, &at24->bin);
680
681 for (i = 1; i < at24->num_addresses; i++)
682 i2c_unregister_device(at24->client[i]);
683
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200684 return 0;
685}
686
687/*-------------------------------------------------------------------------*/
688
689static struct i2c_driver at24_driver = {
690 .driver = {
691 .name = "at24",
692 .owner = THIS_MODULE,
693 },
694 .probe = at24_probe,
Bill Pemberton2d6bed92012-11-19 13:21:23 -0500695 .remove = at24_remove,
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200696 .id_table = at24_ids,
697};
698
699static int __init at24_init(void)
700{
Wolfram Sang45efe842010-11-17 13:00:49 +0100701 if (!io_limit) {
702 pr_err("at24: io_limit must not be 0!\n");
703 return -EINVAL;
704 }
705
Wolfram Sang2b7a5052008-07-14 22:38:35 +0200706 io_limit = rounddown_pow_of_two(io_limit);
707 return i2c_add_driver(&at24_driver);
708}
709module_init(at24_init);
710
711static void __exit at24_exit(void)
712{
713 i2c_del_driver(&at24_driver);
714}
715module_exit(at24_exit);
716
717MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
718MODULE_AUTHOR("David Brownell and Wolfram Sang");
719MODULE_LICENSE("GPL");