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2b7a5056 WS |
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/sysfs.h> | |
19 | #include <linux/mod_devicetable.h> | |
20 | #include <linux/log2.h> | |
21 | #include <linux/bitops.h> | |
22 | #include <linux/jiffies.h> | |
9ed030d7 | 23 | #include <linux/of.h> |
2b7a5056 | 24 | #include <linux/i2c.h> |
25f73ed5 | 25 | #include <linux/platform_data/at24.h> |
2b7a5056 WS |
26 | |
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 | ||
55 | struct at24_data { | |
56 | struct at24_platform_data chip; | |
7274ec8b | 57 | struct memory_accessor macc; |
7aeb9664 | 58 | int use_smbus; |
2b7a5056 WS |
59 | |
60 | /* | |
61 | * Lock protects against activities from other Linux tasks, | |
62 | * but not from changes by other I2C masters. | |
63 | */ | |
64 | struct mutex lock; | |
65 | struct bin_attribute bin; | |
66 | ||
67 | u8 *writebuf; | |
68 | unsigned write_max; | |
69 | unsigned num_addresses; | |
70 | ||
71 | /* | |
72 | * Some chips tie up multiple I2C addresses; dummy devices reserve | |
73 | * them for us, and we'll use them with SMBus calls. | |
74 | */ | |
75 | struct i2c_client *client[]; | |
76 | }; | |
77 | ||
78 | /* | |
79 | * This parameter is to help this driver avoid blocking other drivers out | |
80 | * of I2C for potentially troublesome amounts of time. With a 100 kHz I2C | |
81 | * clock, one 256 byte read takes about 1/43 second which is excessive; | |
82 | * but the 1/170 second it takes at 400 kHz may be quite reasonable; and | |
83 | * at 1 MHz (Fm+) a 1/430 second delay could easily be invisible. | |
84 | * | |
85 | * This value is forced to be a power of two so that writes align on pages. | |
86 | */ | |
87 | static unsigned io_limit = 128; | |
88 | module_param(io_limit, uint, 0); | |
89 | MODULE_PARM_DESC(io_limit, "Maximum bytes per I/O (default 128)"); | |
90 | ||
91 | /* | |
92 | * Specs often allow 5 msec for a page write, sometimes 20 msec; | |
93 | * it's important to recover from write timeouts. | |
94 | */ | |
95 | static unsigned write_timeout = 25; | |
96 | module_param(write_timeout, uint, 0); | |
97 | MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)"); | |
98 | ||
99 | #define AT24_SIZE_BYTELEN 5 | |
100 | #define AT24_SIZE_FLAGS 8 | |
101 | ||
102 | #define AT24_BITMASK(x) (BIT(x) - 1) | |
103 | ||
104 | /* create non-zero magic value for given eeprom parameters */ | |
105 | #define AT24_DEVICE_MAGIC(_len, _flags) \ | |
106 | ((1 << AT24_SIZE_FLAGS | (_flags)) \ | |
107 | << AT24_SIZE_BYTELEN | ilog2(_len)) | |
108 | ||
109 | static const struct i2c_device_id at24_ids[] = { | |
110 | /* needs 8 addresses as A0-A2 are ignored */ | |
111 | { "24c00", AT24_DEVICE_MAGIC(128 / 8, AT24_FLAG_TAKE8ADDR) }, | |
112 | /* old variants can't be handled with this generic entry! */ | |
113 | { "24c01", AT24_DEVICE_MAGIC(1024 / 8, 0) }, | |
114 | { "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) }, | |
115 | /* spd is a 24c02 in memory DIMMs */ | |
116 | { "spd", AT24_DEVICE_MAGIC(2048 / 8, | |
117 | AT24_FLAG_READONLY | AT24_FLAG_IRUGO) }, | |
118 | { "24c04", AT24_DEVICE_MAGIC(4096 / 8, 0) }, | |
119 | /* 24rf08 quirk is handled at i2c-core */ | |
120 | { "24c08", AT24_DEVICE_MAGIC(8192 / 8, 0) }, | |
121 | { "24c16", AT24_DEVICE_MAGIC(16384 / 8, 0) }, | |
122 | { "24c32", AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16) }, | |
123 | { "24c64", AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16) }, | |
124 | { "24c128", AT24_DEVICE_MAGIC(131072 / 8, AT24_FLAG_ADDR16) }, | |
125 | { "24c256", AT24_DEVICE_MAGIC(262144 / 8, AT24_FLAG_ADDR16) }, | |
126 | { "24c512", AT24_DEVICE_MAGIC(524288 / 8, AT24_FLAG_ADDR16) }, | |
127 | { "24c1024", AT24_DEVICE_MAGIC(1048576 / 8, AT24_FLAG_ADDR16) }, | |
128 | { "at24", 0 }, | |
129 | { /* END OF LIST */ } | |
130 | }; | |
131 | MODULE_DEVICE_TABLE(i2c, at24_ids); | |
132 | ||
133 | /*-------------------------------------------------------------------------*/ | |
134 | ||
135 | /* | |
136 | * This routine supports chips which consume multiple I2C addresses. It | |
137 | * computes the addressing information to be used for a given r/w request. | |
138 | * Assumes that sanity checks for offset happened at sysfs-layer. | |
139 | */ | |
140 | static struct i2c_client *at24_translate_offset(struct at24_data *at24, | |
141 | unsigned *offset) | |
142 | { | |
143 | unsigned i; | |
144 | ||
145 | if (at24->chip.flags & AT24_FLAG_ADDR16) { | |
146 | i = *offset >> 16; | |
147 | *offset &= 0xffff; | |
148 | } else { | |
149 | i = *offset >> 8; | |
150 | *offset &= 0xff; | |
151 | } | |
152 | ||
153 | return at24->client[i]; | |
154 | } | |
155 | ||
156 | static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf, | |
157 | unsigned offset, size_t count) | |
158 | { | |
159 | struct i2c_msg msg[2]; | |
160 | u8 msgbuf[2]; | |
161 | struct i2c_client *client; | |
4d29196c | 162 | unsigned long timeout, read_time; |
2b7a5056 WS |
163 | int status, i; |
164 | ||
165 | memset(msg, 0, sizeof(msg)); | |
166 | ||
167 | /* | |
168 | * REVISIT some multi-address chips don't rollover page reads to | |
169 | * the next slave address, so we may need to truncate the count. | |
170 | * Those chips might need another quirk flag. | |
171 | * | |
172 | * If the real hardware used four adjacent 24c02 chips and that | |
173 | * were misconfigured as one 24c08, that would be a similar effect: | |
174 | * one "eeprom" file not four, but larger reads would fail when | |
175 | * they crossed certain pages. | |
176 | */ | |
177 | ||
178 | /* | |
179 | * Slave address and byte offset derive from the offset. Always | |
180 | * set the byte address; on a multi-master board, another master | |
181 | * may have changed the chip's "current" address pointer. | |
182 | */ | |
183 | client = at24_translate_offset(at24, &offset); | |
184 | ||
185 | if (count > io_limit) | |
186 | count = io_limit; | |
187 | ||
7aeb9664 JD |
188 | switch (at24->use_smbus) { |
189 | case I2C_SMBUS_I2C_BLOCK_DATA: | |
4d29196c | 190 | /* Smaller eeproms can work given some SMBus extension calls */ |
2b7a5056 WS |
191 | if (count > I2C_SMBUS_BLOCK_MAX) |
192 | count = I2C_SMBUS_BLOCK_MAX; | |
7aeb9664 JD |
193 | break; |
194 | case I2C_SMBUS_WORD_DATA: | |
195 | count = 2; | |
196 | break; | |
197 | case I2C_SMBUS_BYTE_DATA: | |
198 | count = 1; | |
199 | break; | |
200 | default: | |
4d29196c WS |
201 | /* |
202 | * When we have a better choice than SMBus calls, use a | |
203 | * combined I2C message. Write address; then read up to | |
204 | * io_limit data bytes. Note that read page rollover helps us | |
205 | * here (unlike writes). msgbuf is u8 and will cast to our | |
206 | * needs. | |
207 | */ | |
208 | i = 0; | |
209 | if (at24->chip.flags & AT24_FLAG_ADDR16) | |
210 | msgbuf[i++] = offset >> 8; | |
211 | msgbuf[i++] = offset; | |
212 | ||
213 | msg[0].addr = client->addr; | |
214 | msg[0].buf = msgbuf; | |
215 | msg[0].len = i; | |
216 | ||
217 | msg[1].addr = client->addr; | |
218 | msg[1].flags = I2C_M_RD; | |
219 | msg[1].buf = buf; | |
220 | msg[1].len = count; | |
2b7a5056 WS |
221 | } |
222 | ||
223 | /* | |
4d29196c WS |
224 | * Reads fail if the previous write didn't complete yet. We may |
225 | * loop a few times until this one succeeds, waiting at least | |
226 | * long enough for one entire page write to work. | |
2b7a5056 | 227 | */ |
4d29196c WS |
228 | timeout = jiffies + msecs_to_jiffies(write_timeout); |
229 | do { | |
230 | read_time = jiffies; | |
7aeb9664 JD |
231 | switch (at24->use_smbus) { |
232 | case I2C_SMBUS_I2C_BLOCK_DATA: | |
4d29196c WS |
233 | status = i2c_smbus_read_i2c_block_data(client, offset, |
234 | count, buf); | |
7aeb9664 JD |
235 | break; |
236 | case I2C_SMBUS_WORD_DATA: | |
237 | status = i2c_smbus_read_word_data(client, offset); | |
238 | if (status >= 0) { | |
239 | buf[0] = status & 0xff; | |
240 | buf[1] = status >> 8; | |
241 | status = count; | |
242 | } | |
243 | break; | |
244 | case I2C_SMBUS_BYTE_DATA: | |
245 | status = i2c_smbus_read_byte_data(client, offset); | |
246 | if (status >= 0) { | |
247 | buf[0] = status; | |
248 | status = count; | |
249 | } | |
250 | break; | |
251 | default: | |
4d29196c WS |
252 | status = i2c_transfer(client->adapter, msg, 2); |
253 | if (status == 2) | |
254 | status = count; | |
255 | } | |
256 | dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n", | |
257 | count, offset, status, jiffies); | |
2b7a5056 | 258 | |
4d29196c WS |
259 | if (status == count) |
260 | return count; | |
2b7a5056 | 261 | |
4d29196c WS |
262 | /* REVISIT: at HZ=100, this is sloooow */ |
263 | msleep(1); | |
264 | } while (time_before(read_time, timeout)); | |
2b7a5056 | 265 | |
4d29196c | 266 | return -ETIMEDOUT; |
2b7a5056 WS |
267 | } |
268 | ||
7274ec8b | 269 | static ssize_t at24_read(struct at24_data *at24, |
2b7a5056 WS |
270 | char *buf, loff_t off, size_t count) |
271 | { | |
2b7a5056 WS |
272 | ssize_t retval = 0; |
273 | ||
2b7a5056 WS |
274 | if (unlikely(!count)) |
275 | return count; | |
276 | ||
277 | /* | |
278 | * Read data from chip, protecting against concurrent updates | |
279 | * from this host, but not from other I2C masters. | |
280 | */ | |
281 | mutex_lock(&at24->lock); | |
282 | ||
283 | while (count) { | |
284 | ssize_t status; | |
285 | ||
286 | status = at24_eeprom_read(at24, buf, off, count); | |
287 | if (status <= 0) { | |
288 | if (retval == 0) | |
289 | retval = status; | |
290 | break; | |
291 | } | |
292 | buf += status; | |
293 | off += status; | |
294 | count -= status; | |
295 | retval += status; | |
296 | } | |
297 | ||
298 | mutex_unlock(&at24->lock); | |
299 | ||
300 | return retval; | |
301 | } | |
302 | ||
2c3c8bea CW |
303 | static ssize_t at24_bin_read(struct file *filp, struct kobject *kobj, |
304 | struct bin_attribute *attr, | |
7274ec8b KH |
305 | char *buf, loff_t off, size_t count) |
306 | { | |
307 | struct at24_data *at24; | |
2b7a5056 | 308 | |
7274ec8b KH |
309 | at24 = dev_get_drvdata(container_of(kobj, struct device, kobj)); |
310 | return at24_read(at24, buf, off, count); | |
311 | } | |
2b7a5056 WS |
312 | |
313 | ||
314 | /* | |
315 | * Note that if the hardware write-protect pin is pulled high, the whole | |
316 | * chip is normally write protected. But there are plenty of product | |
317 | * variants here, including OTP fuses and partial chip protect. | |
318 | * | |
319 | * We only use page mode writes; the alternative is sloooow. This routine | |
320 | * writes at most one page. | |
321 | */ | |
280ca299 | 322 | static ssize_t at24_eeprom_write(struct at24_data *at24, const char *buf, |
2b7a5056 WS |
323 | unsigned offset, size_t count) |
324 | { | |
325 | struct i2c_client *client; | |
326 | struct i2c_msg msg; | |
327 | ssize_t status; | |
328 | unsigned long timeout, write_time; | |
329 | unsigned next_page; | |
330 | ||
331 | /* Get corresponding I2C address and adjust offset */ | |
332 | client = at24_translate_offset(at24, &offset); | |
333 | ||
334 | /* write_max is at most a page */ | |
335 | if (count > at24->write_max) | |
336 | count = at24->write_max; | |
337 | ||
338 | /* Never roll over backwards, to the start of this page */ | |
339 | next_page = roundup(offset + 1, at24->chip.page_size); | |
340 | if (offset + count > next_page) | |
341 | count = next_page - offset; | |
342 | ||
343 | /* If we'll use I2C calls for I/O, set up the message */ | |
344 | if (!at24->use_smbus) { | |
345 | int i = 0; | |
346 | ||
347 | msg.addr = client->addr; | |
348 | msg.flags = 0; | |
349 | ||
350 | /* msg.buf is u8 and casts will mask the values */ | |
351 | msg.buf = at24->writebuf; | |
352 | if (at24->chip.flags & AT24_FLAG_ADDR16) | |
353 | msg.buf[i++] = offset >> 8; | |
354 | ||
355 | msg.buf[i++] = offset; | |
356 | memcpy(&msg.buf[i], buf, count); | |
357 | msg.len = i + count; | |
358 | } | |
359 | ||
360 | /* | |
361 | * Writes fail if the previous one didn't complete yet. We may | |
362 | * loop a few times until this one succeeds, waiting at least | |
363 | * long enough for one entire page write to work. | |
364 | */ | |
365 | timeout = jiffies + msecs_to_jiffies(write_timeout); | |
366 | do { | |
367 | write_time = jiffies; | |
368 | if (at24->use_smbus) { | |
369 | status = i2c_smbus_write_i2c_block_data(client, | |
370 | offset, count, buf); | |
371 | if (status == 0) | |
372 | status = count; | |
373 | } else { | |
374 | status = i2c_transfer(client->adapter, &msg, 1); | |
375 | if (status == 1) | |
376 | status = count; | |
377 | } | |
2ce5b34f | 378 | dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n", |
2b7a5056 WS |
379 | count, offset, status, jiffies); |
380 | ||
381 | if (status == count) | |
382 | return count; | |
383 | ||
384 | /* REVISIT: at HZ=100, this is sloooow */ | |
385 | msleep(1); | |
386 | } while (time_before(write_time, timeout)); | |
387 | ||
388 | return -ETIMEDOUT; | |
389 | } | |
390 | ||
280ca299 GU |
391 | static ssize_t at24_write(struct at24_data *at24, const char *buf, loff_t off, |
392 | size_t count) | |
2b7a5056 | 393 | { |
2b7a5056 WS |
394 | ssize_t retval = 0; |
395 | ||
2b7a5056 WS |
396 | if (unlikely(!count)) |
397 | return count; | |
398 | ||
399 | /* | |
400 | * Write data to chip, protecting against concurrent updates | |
401 | * from this host, but not from other I2C masters. | |
402 | */ | |
403 | mutex_lock(&at24->lock); | |
404 | ||
405 | while (count) { | |
406 | ssize_t status; | |
407 | ||
408 | status = at24_eeprom_write(at24, buf, off, count); | |
409 | if (status <= 0) { | |
410 | if (retval == 0) | |
411 | retval = status; | |
412 | break; | |
413 | } | |
414 | buf += status; | |
415 | off += status; | |
416 | count -= status; | |
417 | retval += status; | |
418 | } | |
419 | ||
420 | mutex_unlock(&at24->lock); | |
421 | ||
422 | return retval; | |
423 | } | |
424 | ||
2c3c8bea CW |
425 | static ssize_t at24_bin_write(struct file *filp, struct kobject *kobj, |
426 | struct bin_attribute *attr, | |
7274ec8b KH |
427 | char *buf, loff_t off, size_t count) |
428 | { | |
429 | struct at24_data *at24; | |
430 | ||
431 | at24 = dev_get_drvdata(container_of(kobj, struct device, kobj)); | |
432 | return at24_write(at24, buf, off, count); | |
433 | } | |
434 | ||
435 | /*-------------------------------------------------------------------------*/ | |
436 | ||
437 | /* | |
438 | * This lets other kernel code access the eeprom data. For example, it | |
439 | * might hold a board's Ethernet address, or board-specific calibration | |
440 | * data generated on the manufacturing floor. | |
441 | */ | |
442 | ||
443 | static ssize_t at24_macc_read(struct memory_accessor *macc, char *buf, | |
444 | off_t offset, size_t count) | |
445 | { | |
446 | struct at24_data *at24 = container_of(macc, struct at24_data, macc); | |
447 | ||
448 | return at24_read(at24, buf, offset, count); | |
449 | } | |
450 | ||
280ca299 | 451 | static ssize_t at24_macc_write(struct memory_accessor *macc, const char *buf, |
7274ec8b KH |
452 | off_t offset, size_t count) |
453 | { | |
454 | struct at24_data *at24 = container_of(macc, struct at24_data, macc); | |
455 | ||
456 | return at24_write(at24, buf, offset, count); | |
457 | } | |
458 | ||
2b7a5056 WS |
459 | /*-------------------------------------------------------------------------*/ |
460 | ||
9ed030d7 WS |
461 | #ifdef CONFIG_OF |
462 | static void at24_get_ofdata(struct i2c_client *client, | |
463 | struct at24_platform_data *chip) | |
464 | { | |
465 | const __be32 *val; | |
466 | struct device_node *node = client->dev.of_node; | |
467 | ||
468 | if (node) { | |
469 | if (of_get_property(node, "read-only", NULL)) | |
470 | chip->flags |= AT24_FLAG_READONLY; | |
471 | val = of_get_property(node, "pagesize", NULL); | |
472 | if (val) | |
473 | chip->page_size = be32_to_cpup(val); | |
474 | } | |
475 | } | |
476 | #else | |
477 | static void at24_get_ofdata(struct i2c_client *client, | |
478 | struct at24_platform_data *chip) | |
479 | { } | |
480 | #endif /* CONFIG_OF */ | |
481 | ||
2b7a5056 WS |
482 | static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id) |
483 | { | |
484 | struct at24_platform_data chip; | |
485 | bool writable; | |
7aeb9664 | 486 | int use_smbus = 0; |
2b7a5056 WS |
487 | struct at24_data *at24; |
488 | int err; | |
489 | unsigned i, num_addresses; | |
490 | kernel_ulong_t magic; | |
491 | ||
492 | if (client->dev.platform_data) { | |
493 | chip = *(struct at24_platform_data *)client->dev.platform_data; | |
494 | } else { | |
f0ac2363 NB |
495 | if (!id->driver_data) |
496 | return -ENODEV; | |
497 | ||
2b7a5056 WS |
498 | magic = id->driver_data; |
499 | chip.byte_len = BIT(magic & AT24_BITMASK(AT24_SIZE_BYTELEN)); | |
500 | magic >>= AT24_SIZE_BYTELEN; | |
501 | chip.flags = magic & AT24_BITMASK(AT24_SIZE_FLAGS); | |
502 | /* | |
503 | * This is slow, but we can't know all eeproms, so we better | |
504 | * play safe. Specifying custom eeprom-types via platform_data | |
505 | * is recommended anyhow. | |
506 | */ | |
507 | chip.page_size = 1; | |
7274ec8b | 508 | |
9ed030d7 WS |
509 | /* update chipdata if OF is present */ |
510 | at24_get_ofdata(client, &chip); | |
511 | ||
7274ec8b KH |
512 | chip.setup = NULL; |
513 | chip.context = NULL; | |
2b7a5056 WS |
514 | } |
515 | ||
516 | if (!is_power_of_2(chip.byte_len)) | |
517 | dev_warn(&client->dev, | |
518 | "byte_len looks suspicious (no power of 2)!\n"); | |
45efe847 WS |
519 | if (!chip.page_size) { |
520 | dev_err(&client->dev, "page_size must not be 0!\n"); | |
f0ac2363 | 521 | return -EINVAL; |
45efe847 | 522 | } |
2b7a5056 WS |
523 | if (!is_power_of_2(chip.page_size)) |
524 | dev_warn(&client->dev, | |
525 | "page_size looks suspicious (no power of 2)!\n"); | |
526 | ||
527 | /* Use I2C operations unless we're stuck with SMBus extensions. */ | |
528 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) { | |
f0ac2363 NB |
529 | if (chip.flags & AT24_FLAG_ADDR16) |
530 | return -EPFNOSUPPORT; | |
531 | ||
7aeb9664 | 532 | if (i2c_check_functionality(client->adapter, |
2b7a5056 | 533 | I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { |
7aeb9664 JD |
534 | use_smbus = I2C_SMBUS_I2C_BLOCK_DATA; |
535 | } else if (i2c_check_functionality(client->adapter, | |
536 | I2C_FUNC_SMBUS_READ_WORD_DATA)) { | |
537 | use_smbus = I2C_SMBUS_WORD_DATA; | |
538 | } else if (i2c_check_functionality(client->adapter, | |
539 | I2C_FUNC_SMBUS_READ_BYTE_DATA)) { | |
540 | use_smbus = I2C_SMBUS_BYTE_DATA; | |
541 | } else { | |
f0ac2363 | 542 | return -EPFNOSUPPORT; |
2b7a5056 | 543 | } |
2b7a5056 WS |
544 | } |
545 | ||
546 | if (chip.flags & AT24_FLAG_TAKE8ADDR) | |
547 | num_addresses = 8; | |
548 | else | |
549 | num_addresses = DIV_ROUND_UP(chip.byte_len, | |
550 | (chip.flags & AT24_FLAG_ADDR16) ? 65536 : 256); | |
551 | ||
f0ac2363 | 552 | at24 = devm_kzalloc(&client->dev, sizeof(struct at24_data) + |
2b7a5056 | 553 | num_addresses * sizeof(struct i2c_client *), GFP_KERNEL); |
f0ac2363 NB |
554 | if (!at24) |
555 | return -ENOMEM; | |
2b7a5056 WS |
556 | |
557 | mutex_init(&at24->lock); | |
558 | at24->use_smbus = use_smbus; | |
559 | at24->chip = chip; | |
560 | at24->num_addresses = num_addresses; | |
561 | ||
562 | /* | |
563 | * Export the EEPROM bytes through sysfs, since that's convenient. | |
564 | * By default, only root should see the data (maybe passwords etc) | |
565 | */ | |
d07b56b3 | 566 | sysfs_bin_attr_init(&at24->bin); |
2b7a5056 WS |
567 | at24->bin.attr.name = "eeprom"; |
568 | at24->bin.attr.mode = chip.flags & AT24_FLAG_IRUGO ? S_IRUGO : S_IRUSR; | |
2b7a5056 WS |
569 | at24->bin.read = at24_bin_read; |
570 | at24->bin.size = chip.byte_len; | |
571 | ||
7274ec8b KH |
572 | at24->macc.read = at24_macc_read; |
573 | ||
2b7a5056 WS |
574 | writable = !(chip.flags & AT24_FLAG_READONLY); |
575 | if (writable) { | |
576 | if (!use_smbus || i2c_check_functionality(client->adapter, | |
577 | I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) { | |
578 | ||
579 | unsigned write_max = chip.page_size; | |
580 | ||
7274ec8b KH |
581 | at24->macc.write = at24_macc_write; |
582 | ||
2b7a5056 WS |
583 | at24->bin.write = at24_bin_write; |
584 | at24->bin.attr.mode |= S_IWUSR; | |
585 | ||
586 | if (write_max > io_limit) | |
587 | write_max = io_limit; | |
588 | if (use_smbus && write_max > I2C_SMBUS_BLOCK_MAX) | |
589 | write_max = I2C_SMBUS_BLOCK_MAX; | |
590 | at24->write_max = write_max; | |
591 | ||
592 | /* buffer (data + address at the beginning) */ | |
f0ac2363 NB |
593 | at24->writebuf = devm_kzalloc(&client->dev, |
594 | write_max + 2, GFP_KERNEL); | |
595 | if (!at24->writebuf) | |
596 | return -ENOMEM; | |
2b7a5056 WS |
597 | } else { |
598 | dev_warn(&client->dev, | |
599 | "cannot write due to controller restrictions."); | |
600 | } | |
601 | } | |
602 | ||
603 | at24->client[0] = client; | |
604 | ||
605 | /* use dummy devices for multiple-address chips */ | |
606 | for (i = 1; i < num_addresses; i++) { | |
607 | at24->client[i] = i2c_new_dummy(client->adapter, | |
608 | client->addr + i); | |
609 | if (!at24->client[i]) { | |
610 | dev_err(&client->dev, "address 0x%02x unavailable\n", | |
611 | client->addr + i); | |
612 | err = -EADDRINUSE; | |
613 | goto err_clients; | |
614 | } | |
615 | } | |
616 | ||
617 | err = sysfs_create_bin_file(&client->dev.kobj, &at24->bin); | |
618 | if (err) | |
619 | goto err_clients; | |
620 | ||
621 | i2c_set_clientdata(client, at24); | |
622 | ||
9ed030d7 | 623 | dev_info(&client->dev, "%zu byte %s EEPROM, %s, %u bytes/write\n", |
2b7a5056 | 624 | at24->bin.size, client->name, |
9ed030d7 | 625 | writable ? "writable" : "read-only", at24->write_max); |
7aeb9664 JD |
626 | if (use_smbus == I2C_SMBUS_WORD_DATA || |
627 | use_smbus == I2C_SMBUS_BYTE_DATA) { | |
628 | dev_notice(&client->dev, "Falling back to %s reads, " | |
629 | "performance will suffer\n", use_smbus == | |
630 | I2C_SMBUS_WORD_DATA ? "word" : "byte"); | |
631 | } | |
2b7a5056 | 632 | |
7274ec8b KH |
633 | /* export data to kernel code */ |
634 | if (chip.setup) | |
635 | chip.setup(&at24->macc, chip.context); | |
636 | ||
2b7a5056 WS |
637 | return 0; |
638 | ||
639 | err_clients: | |
640 | for (i = 1; i < num_addresses; i++) | |
641 | if (at24->client[i]) | |
642 | i2c_unregister_device(at24->client[i]); | |
643 | ||
2b7a5056 WS |
644 | return err; |
645 | } | |
646 | ||
486a5c28 | 647 | static int at24_remove(struct i2c_client *client) |
2b7a5056 WS |
648 | { |
649 | struct at24_data *at24; | |
650 | int i; | |
651 | ||
652 | at24 = i2c_get_clientdata(client); | |
653 | sysfs_remove_bin_file(&client->dev.kobj, &at24->bin); | |
654 | ||
655 | for (i = 1; i < at24->num_addresses; i++) | |
656 | i2c_unregister_device(at24->client[i]); | |
657 | ||
2b7a5056 WS |
658 | return 0; |
659 | } | |
660 | ||
661 | /*-------------------------------------------------------------------------*/ | |
662 | ||
663 | static struct i2c_driver at24_driver = { | |
664 | .driver = { | |
665 | .name = "at24", | |
666 | .owner = THIS_MODULE, | |
667 | }, | |
668 | .probe = at24_probe, | |
2d6bed9c | 669 | .remove = at24_remove, |
2b7a5056 WS |
670 | .id_table = at24_ids, |
671 | }; | |
672 | ||
673 | static int __init at24_init(void) | |
674 | { | |
45efe847 WS |
675 | if (!io_limit) { |
676 | pr_err("at24: io_limit must not be 0!\n"); | |
677 | return -EINVAL; | |
678 | } | |
679 | ||
2b7a5056 WS |
680 | io_limit = rounddown_pow_of_two(io_limit); |
681 | return i2c_add_driver(&at24_driver); | |
682 | } | |
683 | module_init(at24_init); | |
684 | ||
685 | static void __exit at24_exit(void) | |
686 | { | |
687 | i2c_del_driver(&at24_driver); | |
688 | } | |
689 | module_exit(at24_exit); | |
690 | ||
691 | MODULE_DESCRIPTION("Driver for most I2C EEPROMs"); | |
692 | MODULE_AUTHOR("David Brownell and Wolfram Sang"); | |
693 | MODULE_LICENSE("GPL"); |