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1// SPDX-License-Identifier: GPL-2.0+
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/kernel.h>
10#include <linux/init.h>
11#include <linux/module.h>
12#include <linux/of_device.h>
13#include <linux/slab.h>
14#include <linux/delay.h>
15#include <linux/mutex.h>
16#include <linux/mod_devicetable.h>
17#include <linux/bitops.h>
18#include <linux/jiffies.h>
19#include <linux/property.h>
20#include <linux/acpi.h>
21#include <linux/i2c.h>
22#include <linux/nvmem-provider.h>
23#include <linux/regmap.h>
24#include <linux/pm_runtime.h>
25#include <linux/gpio/consumer.h>
26
27/* Address pointer is 16 bit. */
28#define AT24_FLAG_ADDR16 BIT(7)
29/* sysfs-entry will be read-only. */
30#define AT24_FLAG_READONLY BIT(6)
31/* sysfs-entry will be world-readable. */
32#define AT24_FLAG_IRUGO BIT(5)
33/* Take always 8 addresses (24c00). */
34#define AT24_FLAG_TAKE8ADDR BIT(4)
35/* Factory-programmed serial number. */
36#define AT24_FLAG_SERIAL BIT(3)
37/* Factory-programmed mac address. */
38#define AT24_FLAG_MAC BIT(2)
39/* Does not auto-rollover reads to the next slave address. */
40#define AT24_FLAG_NO_RDROL BIT(1)
41
42/*
43 * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
44 * Differences between different vendor product lines (like Atmel AT24C or
45 * MicroChip 24LC, etc) won't much matter for typical read/write access.
46 * There are also I2C RAM chips, likewise interchangeable. One example
47 * would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
48 *
49 * However, misconfiguration can lose data. "Set 16-bit memory address"
50 * to a part with 8-bit addressing will overwrite data. Writing with too
51 * big a page size also loses data. And it's not safe to assume that the
52 * conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
53 * uses 0x51, for just one example.
54 *
55 * Accordingly, explicit board-specific configuration data should be used
56 * in almost all cases. (One partial exception is an SMBus used to access
57 * "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
58 *
59 * So this driver uses "new style" I2C driver binding, expecting to be
60 * told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
61 * similar kernel-resident tables; or, configuration data coming from
62 * a bootloader.
63 *
64 * Other than binding model, current differences from "eeprom" driver are
65 * that this one handles write access and isn't restricted to 24c02 devices.
66 * It also handles larger devices (32 kbit and up) with two-byte addresses,
67 * which won't work on pure SMBus systems.
68 */
69
70struct at24_client {
71 struct i2c_client *client;
72 struct regmap *regmap;
73};
74
75struct at24_data {
76 /*
77 * Lock protects against activities from other Linux tasks,
78 * but not from changes by other I2C masters.
79 */
80 struct mutex lock;
81
82 unsigned int write_max;
83 unsigned int num_addresses;
84 unsigned int offset_adj;
85
86 u32 byte_len;
87 u16 page_size;
88 u8 flags;
89
90 struct nvmem_device *nvmem;
91
92 struct gpio_desc *wp_gpio;
93
94 /*
95 * Some chips tie up multiple I2C addresses; dummy devices reserve
96 * them for us, and we'll use them with SMBus calls.
97 */
98 struct at24_client client[];
99};
100
101/*
102 * This parameter is to help this driver avoid blocking other drivers out
103 * of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
104 * clock, one 256 byte read takes about 1/43 second which is excessive;
105 * but the 1/170 second it takes at 400 kHz may be quite reasonable; and
106 * at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
107 *
108 * This value is forced to be a power of two so that writes align on pages.
109 */
110static unsigned int at24_io_limit = 128;
111module_param_named(io_limit, at24_io_limit, uint, 0);
112MODULE_PARM_DESC(at24_io_limit, "Maximum bytes per I/O (default 128)");
113
114/*
115 * Specs often allow 5 msec for a page write, sometimes 20 msec;
116 * it's important to recover from write timeouts.
117 */
118static unsigned int at24_write_timeout = 25;
119module_param_named(write_timeout, at24_write_timeout, uint, 0);
120MODULE_PARM_DESC(at24_write_timeout, "Time (in ms) to try writes (default 25)");
121
122struct at24_chip_data {
123 u32 byte_len;
124 u8 flags;
125};
126
127#define AT24_CHIP_DATA(_name, _len, _flags) \
128 static const struct at24_chip_data _name = { \
129 .byte_len = _len, .flags = _flags, \
130 }
131
132/* needs 8 addresses as A0-A2 are ignored */
133AT24_CHIP_DATA(at24_data_24c00, 128 / 8, AT24_FLAG_TAKE8ADDR);
134/* old variants can't be handled with this generic entry! */
135AT24_CHIP_DATA(at24_data_24c01, 1024 / 8, 0);
136AT24_CHIP_DATA(at24_data_24cs01, 16,
137 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
138AT24_CHIP_DATA(at24_data_24c02, 2048 / 8, 0);
139AT24_CHIP_DATA(at24_data_24cs02, 16,
140 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
141AT24_CHIP_DATA(at24_data_24mac402, 48 / 8,
142 AT24_FLAG_MAC | AT24_FLAG_READONLY);
143AT24_CHIP_DATA(at24_data_24mac602, 64 / 8,
144 AT24_FLAG_MAC | AT24_FLAG_READONLY);
145/* spd is a 24c02 in memory DIMMs */
146AT24_CHIP_DATA(at24_data_spd, 2048 / 8,
147 AT24_FLAG_READONLY | AT24_FLAG_IRUGO);
148AT24_CHIP_DATA(at24_data_24c04, 4096 / 8, 0);
149AT24_CHIP_DATA(at24_data_24cs04, 16,
150 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
151/* 24rf08 quirk is handled at i2c-core */
152AT24_CHIP_DATA(at24_data_24c08, 8192 / 8, 0);
153AT24_CHIP_DATA(at24_data_24cs08, 16,
154 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
155AT24_CHIP_DATA(at24_data_24c16, 16384 / 8, 0);
156AT24_CHIP_DATA(at24_data_24cs16, 16,
157 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
158AT24_CHIP_DATA(at24_data_24c32, 32768 / 8, AT24_FLAG_ADDR16);
159AT24_CHIP_DATA(at24_data_24cs32, 16,
160 AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
161AT24_CHIP_DATA(at24_data_24c64, 65536 / 8, AT24_FLAG_ADDR16);
162AT24_CHIP_DATA(at24_data_24cs64, 16,
163 AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
164AT24_CHIP_DATA(at24_data_24c128, 131072 / 8, AT24_FLAG_ADDR16);
165AT24_CHIP_DATA(at24_data_24c256, 262144 / 8, AT24_FLAG_ADDR16);
166AT24_CHIP_DATA(at24_data_24c512, 524288 / 8, AT24_FLAG_ADDR16);
167AT24_CHIP_DATA(at24_data_24c1024, 1048576 / 8, AT24_FLAG_ADDR16);
168AT24_CHIP_DATA(at24_data_24c2048, 2097152 / 8, AT24_FLAG_ADDR16);
169/* identical to 24c08 ? */
170AT24_CHIP_DATA(at24_data_INT3499, 8192 / 8, 0);
171
172static const struct i2c_device_id at24_ids[] = {
173 { "24c00", (kernel_ulong_t)&at24_data_24c00 },
174 { "24c01", (kernel_ulong_t)&at24_data_24c01 },
175 { "24cs01", (kernel_ulong_t)&at24_data_24cs01 },
176 { "24c02", (kernel_ulong_t)&at24_data_24c02 },
177 { "24cs02", (kernel_ulong_t)&at24_data_24cs02 },
178 { "24mac402", (kernel_ulong_t)&at24_data_24mac402 },
179 { "24mac602", (kernel_ulong_t)&at24_data_24mac602 },
180 { "spd", (kernel_ulong_t)&at24_data_spd },
181 { "24c04", (kernel_ulong_t)&at24_data_24c04 },
182 { "24cs04", (kernel_ulong_t)&at24_data_24cs04 },
183 { "24c08", (kernel_ulong_t)&at24_data_24c08 },
184 { "24cs08", (kernel_ulong_t)&at24_data_24cs08 },
185 { "24c16", (kernel_ulong_t)&at24_data_24c16 },
186 { "24cs16", (kernel_ulong_t)&at24_data_24cs16 },
187 { "24c32", (kernel_ulong_t)&at24_data_24c32 },
188 { "24cs32", (kernel_ulong_t)&at24_data_24cs32 },
189 { "24c64", (kernel_ulong_t)&at24_data_24c64 },
190 { "24cs64", (kernel_ulong_t)&at24_data_24cs64 },
191 { "24c128", (kernel_ulong_t)&at24_data_24c128 },
192 { "24c256", (kernel_ulong_t)&at24_data_24c256 },
193 { "24c512", (kernel_ulong_t)&at24_data_24c512 },
194 { "24c1024", (kernel_ulong_t)&at24_data_24c1024 },
195 { "24c2048", (kernel_ulong_t)&at24_data_24c2048 },
196 { "at24", 0 },
197 { /* END OF LIST */ }
198};
199MODULE_DEVICE_TABLE(i2c, at24_ids);
200
201static const struct of_device_id at24_of_match[] = {
202 { .compatible = "atmel,24c00", .data = &at24_data_24c00 },
203 { .compatible = "atmel,24c01", .data = &at24_data_24c01 },
204 { .compatible = "atmel,24cs01", .data = &at24_data_24cs01 },
205 { .compatible = "atmel,24c02", .data = &at24_data_24c02 },
206 { .compatible = "atmel,24cs02", .data = &at24_data_24cs02 },
207 { .compatible = "atmel,24mac402", .data = &at24_data_24mac402 },
208 { .compatible = "atmel,24mac602", .data = &at24_data_24mac602 },
209 { .compatible = "atmel,spd", .data = &at24_data_spd },
210 { .compatible = "atmel,24c04", .data = &at24_data_24c04 },
211 { .compatible = "atmel,24cs04", .data = &at24_data_24cs04 },
212 { .compatible = "atmel,24c08", .data = &at24_data_24c08 },
213 { .compatible = "atmel,24cs08", .data = &at24_data_24cs08 },
214 { .compatible = "atmel,24c16", .data = &at24_data_24c16 },
215 { .compatible = "atmel,24cs16", .data = &at24_data_24cs16 },
216 { .compatible = "atmel,24c32", .data = &at24_data_24c32 },
217 { .compatible = "atmel,24cs32", .data = &at24_data_24cs32 },
218 { .compatible = "atmel,24c64", .data = &at24_data_24c64 },
219 { .compatible = "atmel,24cs64", .data = &at24_data_24cs64 },
220 { .compatible = "atmel,24c128", .data = &at24_data_24c128 },
221 { .compatible = "atmel,24c256", .data = &at24_data_24c256 },
222 { .compatible = "atmel,24c512", .data = &at24_data_24c512 },
223 { .compatible = "atmel,24c1024", .data = &at24_data_24c1024 },
224 { .compatible = "atmel,24c2048", .data = &at24_data_24c2048 },
225 { /* END OF LIST */ },
226};
227MODULE_DEVICE_TABLE(of, at24_of_match);
228
229static const struct acpi_device_id at24_acpi_ids[] = {
230 { "INT3499", (kernel_ulong_t)&at24_data_INT3499 },
231 { /* END OF LIST */ }
232};
233MODULE_DEVICE_TABLE(acpi, at24_acpi_ids);
234
235/*
236 * This routine supports chips which consume multiple I2C addresses. It
237 * computes the addressing information to be used for a given r/w request.
238 * Assumes that sanity checks for offset happened at sysfs-layer.
239 *
240 * Slave address and byte offset derive from the offset. Always
241 * set the byte address; on a multi-master board, another master
242 * may have changed the chip's "current" address pointer.
243 */
244static struct at24_client *at24_translate_offset(struct at24_data *at24,
245 unsigned int *offset)
246{
247 unsigned int i;
248
249 if (at24->flags & AT24_FLAG_ADDR16) {
250 i = *offset >> 16;
251 *offset &= 0xffff;
252 } else {
253 i = *offset >> 8;
254 *offset &= 0xff;
255 }
256
257 return &at24->client[i];
258}
259
260static struct device *at24_base_client_dev(struct at24_data *at24)
261{
262 return &at24->client[0].client->dev;
263}
264
265static size_t at24_adjust_read_count(struct at24_data *at24,
266 unsigned int offset, size_t count)
267{
268 unsigned int bits;
269 size_t remainder;
270
271 /*
272 * In case of multi-address chips that don't rollover reads to
273 * the next slave address: truncate the count to the slave boundary,
274 * so that the read never straddles slaves.
275 */
276 if (at24->flags & AT24_FLAG_NO_RDROL) {
277 bits = (at24->flags & AT24_FLAG_ADDR16) ? 16 : 8;
278 remainder = BIT(bits) - offset;
279 if (count > remainder)
280 count = remainder;
281 }
282
283 if (count > at24_io_limit)
284 count = at24_io_limit;
285
286 return count;
287}
288
289static ssize_t at24_regmap_read(struct at24_data *at24, char *buf,
290 unsigned int offset, size_t count)
291{
292 unsigned long timeout, read_time;
293 struct at24_client *at24_client;
294 struct i2c_client *client;
295 struct regmap *regmap;
296 int ret;
297
298 at24_client = at24_translate_offset(at24, &offset);
299 regmap = at24_client->regmap;
300 client = at24_client->client;
301 count = at24_adjust_read_count(at24, offset, count);
302
303 /* adjust offset for mac and serial read ops */
304 offset += at24->offset_adj;
305
306 timeout = jiffies + msecs_to_jiffies(at24_write_timeout);
307 do {
308 /*
309 * The timestamp shall be taken before the actual operation
310 * to avoid a premature timeout in case of high CPU load.
311 */
312 read_time = jiffies;
313
314 ret = regmap_bulk_read(regmap, offset, buf, count);
315 dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
316 count, offset, ret, jiffies);
317 if (!ret)
318 return count;
319
320 usleep_range(1000, 1500);
321 } while (time_before(read_time, timeout));
322
323 return -ETIMEDOUT;
324}
325
326/*
327 * Note that if the hardware write-protect pin is pulled high, the whole
328 * chip is normally write protected. But there are plenty of product
329 * variants here, including OTP fuses and partial chip protect.
330 *
331 * We only use page mode writes; the alternative is sloooow. These routines
332 * write at most one page.
333 */
334
335static size_t at24_adjust_write_count(struct at24_data *at24,
336 unsigned int offset, size_t count)
337{
338 unsigned int next_page;
339
340 /* write_max is at most a page */
341 if (count > at24->write_max)
342 count = at24->write_max;
343
344 /* Never roll over backwards, to the start of this page */
345 next_page = roundup(offset + 1, at24->page_size);
346 if (offset + count > next_page)
347 count = next_page - offset;
348
349 return count;
350}
351
352static ssize_t at24_regmap_write(struct at24_data *at24, const char *buf,
353 unsigned int offset, size_t count)
354{
355 unsigned long timeout, write_time;
356 struct at24_client *at24_client;
357 struct i2c_client *client;
358 struct regmap *regmap;
359 int ret;
360
361 at24_client = at24_translate_offset(at24, &offset);
362 regmap = at24_client->regmap;
363 client = at24_client->client;
364 count = at24_adjust_write_count(at24, offset, count);
365 timeout = jiffies + msecs_to_jiffies(at24_write_timeout);
366
367 do {
368 /*
369 * The timestamp shall be taken before the actual operation
370 * to avoid a premature timeout in case of high CPU load.
371 */
372 write_time = jiffies;
373
374 ret = regmap_bulk_write(regmap, offset, buf, count);
375 dev_dbg(&client->dev, "write %zu@%d --> %d (%ld)\n",
376 count, offset, ret, jiffies);
377 if (!ret)
378 return count;
379
380 usleep_range(1000, 1500);
381 } while (time_before(write_time, timeout));
382
383 return -ETIMEDOUT;
384}
385
386static int at24_read(void *priv, unsigned int off, void *val, size_t count)
387{
388 struct at24_data *at24;
389 struct device *dev;
390 char *buf = val;
391 int ret;
392
393 at24 = priv;
394 dev = at24_base_client_dev(at24);
395
396 if (unlikely(!count))
397 return count;
398
399 if (off + count > at24->byte_len)
400 return -EINVAL;
401
402 ret = pm_runtime_get_sync(dev);
403 if (ret < 0) {
404 pm_runtime_put_noidle(dev);
405 return ret;
406 }
407
408 /*
409 * Read data from chip, protecting against concurrent updates
410 * from this host, but not from other I2C masters.
411 */
412 mutex_lock(&at24->lock);
413
414 while (count) {
415 ret = at24_regmap_read(at24, buf, off, count);
416 if (ret < 0) {
417 mutex_unlock(&at24->lock);
418 pm_runtime_put(dev);
419 return ret;
420 }
421 buf += ret;
422 off += ret;
423 count -= ret;
424 }
425
426 mutex_unlock(&at24->lock);
427
428 pm_runtime_put(dev);
429
430 return 0;
431}
432
433static int at24_write(void *priv, unsigned int off, void *val, size_t count)
434{
435 struct at24_data *at24;
436 struct device *dev;
437 char *buf = val;
438 int ret;
439
440 at24 = priv;
441 dev = at24_base_client_dev(at24);
442
443 if (unlikely(!count))
444 return -EINVAL;
445
446 if (off + count > at24->byte_len)
447 return -EINVAL;
448
449 ret = pm_runtime_get_sync(dev);
450 if (ret < 0) {
451 pm_runtime_put_noidle(dev);
452 return ret;
453 }
454
455 /*
456 * Write data to chip, protecting against concurrent updates
457 * from this host, but not from other I2C masters.
458 */
459 mutex_lock(&at24->lock);
460 gpiod_set_value_cansleep(at24->wp_gpio, 0);
461
462 while (count) {
463 ret = at24_regmap_write(at24, buf, off, count);
464 if (ret < 0) {
465 gpiod_set_value_cansleep(at24->wp_gpio, 1);
466 mutex_unlock(&at24->lock);
467 pm_runtime_put(dev);
468 return ret;
469 }
470 buf += ret;
471 off += ret;
472 count -= ret;
473 }
474
475 gpiod_set_value_cansleep(at24->wp_gpio, 1);
476 mutex_unlock(&at24->lock);
477
478 pm_runtime_put(dev);
479
480 return 0;
481}
482
483static const struct at24_chip_data *at24_get_chip_data(struct device *dev)
484{
485 struct device_node *of_node = dev->of_node;
486 const struct at24_chip_data *cdata;
487 const struct i2c_device_id *id;
488
489 id = i2c_match_id(at24_ids, to_i2c_client(dev));
490
491 /*
492 * The I2C core allows OF nodes compatibles to match against the
493 * I2C device ID table as a fallback, so check not only if an OF
494 * node is present but also if it matches an OF device ID entry.
495 */
496 if (of_node && of_match_device(at24_of_match, dev))
497 cdata = of_device_get_match_data(dev);
498 else if (id)
499 cdata = (void *)id->driver_data;
500 else
501 cdata = acpi_device_get_match_data(dev);
502
503 if (!cdata)
504 return ERR_PTR(-ENODEV);
505
506 return cdata;
507}
508
509static int at24_make_dummy_client(struct at24_data *at24, unsigned int index,
510 struct regmap_config *regmap_config)
511{
512 struct i2c_client *base_client, *dummy_client;
513 struct regmap *regmap;
514 struct device *dev;
515
516 base_client = at24->client[0].client;
517 dev = &base_client->dev;
518
519 dummy_client = devm_i2c_new_dummy_device(dev, base_client->adapter,
520 base_client->addr + index);
521 if (IS_ERR(dummy_client))
522 return PTR_ERR(dummy_client);
523
524 regmap = devm_regmap_init_i2c(dummy_client, regmap_config);
525 if (IS_ERR(regmap))
526 return PTR_ERR(regmap);
527
528 at24->client[index].client = dummy_client;
529 at24->client[index].regmap = regmap;
530
531 return 0;
532}
533
534static unsigned int at24_get_offset_adj(u8 flags, unsigned int byte_len)
535{
536 if (flags & AT24_FLAG_MAC) {
537 /* EUI-48 starts from 0x9a, EUI-64 from 0x98 */
538 return 0xa0 - byte_len;
539 } else if (flags & AT24_FLAG_SERIAL && flags & AT24_FLAG_ADDR16) {
540 /*
541 * For 16 bit address pointers, the word address must contain
542 * a '10' sequence in bits 11 and 10 regardless of the
543 * intended position of the address pointer.
544 */
545 return 0x0800;
546 } else if (flags & AT24_FLAG_SERIAL) {
547 /*
548 * Otherwise the word address must begin with a '10' sequence,
549 * regardless of the intended address.
550 */
551 return 0x0080;
552 } else {
553 return 0;
554 }
555}
556
557static int at24_probe(struct i2c_client *client)
558{
559 struct regmap_config regmap_config = { };
560 struct nvmem_config nvmem_config = { };
561 u32 byte_len, page_size, flags, addrw;
562 const struct at24_chip_data *cdata;
563 struct device *dev = &client->dev;
564 bool i2c_fn_i2c, i2c_fn_block;
565 unsigned int i, num_addresses;
566 struct at24_data *at24;
567 struct regmap *regmap;
568 bool writable;
569 u8 test_byte;
570 int err;
571
572 i2c_fn_i2c = i2c_check_functionality(client->adapter, I2C_FUNC_I2C);
573 i2c_fn_block = i2c_check_functionality(client->adapter,
574 I2C_FUNC_SMBUS_WRITE_I2C_BLOCK);
575
576 cdata = at24_get_chip_data(dev);
577 if (IS_ERR(cdata))
578 return PTR_ERR(cdata);
579
580 err = device_property_read_u32(dev, "pagesize", &page_size);
581 if (err)
582 /*
583 * This is slow, but we can't know all eeproms, so we better
584 * play safe. Specifying custom eeprom-types via device tree
585 * or properties is recommended anyhow.
586 */
587 page_size = 1;
588
589 flags = cdata->flags;
590 if (device_property_present(dev, "read-only"))
591 flags |= AT24_FLAG_READONLY;
592 if (device_property_present(dev, "no-read-rollover"))
593 flags |= AT24_FLAG_NO_RDROL;
594
595 err = device_property_read_u32(dev, "address-width", &addrw);
596 if (!err) {
597 switch (addrw) {
598 case 8:
599 if (flags & AT24_FLAG_ADDR16)
600 dev_warn(dev,
601 "Override address width to be 8, while default is 16\n");
602 flags &= ~AT24_FLAG_ADDR16;
603 break;
604 case 16:
605 flags |= AT24_FLAG_ADDR16;
606 break;
607 default:
608 dev_warn(dev, "Bad \"address-width\" property: %u\n",
609 addrw);
610 }
611 }
612
613 err = device_property_read_u32(dev, "size", &byte_len);
614 if (err)
615 byte_len = cdata->byte_len;
616
617 if (!i2c_fn_i2c && !i2c_fn_block)
618 page_size = 1;
619
620 if (!page_size) {
621 dev_err(dev, "page_size must not be 0!\n");
622 return -EINVAL;
623 }
624
625 if (!is_power_of_2(page_size))
626 dev_warn(dev, "page_size looks suspicious (no power of 2)!\n");
627
628 err = device_property_read_u32(dev, "num-addresses", &num_addresses);
629 if (err) {
630 if (flags & AT24_FLAG_TAKE8ADDR)
631 num_addresses = 8;
632 else
633 num_addresses = DIV_ROUND_UP(byte_len,
634 (flags & AT24_FLAG_ADDR16) ? 65536 : 256);
635 }
636
637 if ((flags & AT24_FLAG_SERIAL) && (flags & AT24_FLAG_MAC)) {
638 dev_err(dev,
639 "invalid device data - cannot have both AT24_FLAG_SERIAL & AT24_FLAG_MAC.");
640 return -EINVAL;
641 }
642
643 regmap_config.val_bits = 8;
644 regmap_config.reg_bits = (flags & AT24_FLAG_ADDR16) ? 16 : 8;
645 regmap_config.disable_locking = true;
646
647 regmap = devm_regmap_init_i2c(client, ®map_config);
648 if (IS_ERR(regmap))
649 return PTR_ERR(regmap);
650
651 at24 = devm_kzalloc(dev, struct_size(at24, client, num_addresses),
652 GFP_KERNEL);
653 if (!at24)
654 return -ENOMEM;
655
656 mutex_init(&at24->lock);
657 at24->byte_len = byte_len;
658 at24->page_size = page_size;
659 at24->flags = flags;
660 at24->num_addresses = num_addresses;
661 at24->offset_adj = at24_get_offset_adj(flags, byte_len);
662 at24->client[0].client = client;
663 at24->client[0].regmap = regmap;
664
665 at24->wp_gpio = devm_gpiod_get_optional(dev, "wp", GPIOD_OUT_HIGH);
666 if (IS_ERR(at24->wp_gpio))
667 return PTR_ERR(at24->wp_gpio);
668
669 writable = !(flags & AT24_FLAG_READONLY);
670 if (writable) {
671 at24->write_max = min_t(unsigned int,
672 page_size, at24_io_limit);
673 if (!i2c_fn_i2c && at24->write_max > I2C_SMBUS_BLOCK_MAX)
674 at24->write_max = I2C_SMBUS_BLOCK_MAX;
675 }
676
677 /* use dummy devices for multiple-address chips */
678 for (i = 1; i < num_addresses; i++) {
679 err = at24_make_dummy_client(at24, i, ®map_config);
680 if (err)
681 return err;
682 }
683
684 nvmem_config.name = dev_name(dev);
685 nvmem_config.dev = dev;
686 nvmem_config.read_only = !writable;
687 nvmem_config.root_only = !(flags & AT24_FLAG_IRUGO);
688 nvmem_config.owner = THIS_MODULE;
689 nvmem_config.compat = true;
690 nvmem_config.base_dev = dev;
691 nvmem_config.reg_read = at24_read;
692 nvmem_config.reg_write = at24_write;
693 nvmem_config.priv = at24;
694 nvmem_config.stride = 1;
695 nvmem_config.word_size = 1;
696 nvmem_config.size = byte_len;
697
698 at24->nvmem = devm_nvmem_register(dev, &nvmem_config);
699 if (IS_ERR(at24->nvmem))
700 return PTR_ERR(at24->nvmem);
701
702 i2c_set_clientdata(client, at24);
703
704 /* enable runtime pm */
705 pm_runtime_set_active(dev);
706 pm_runtime_enable(dev);
707
708 /*
709 * Perform a one-byte test read to verify that the
710 * chip is functional.
711 */
712 err = at24_read(at24, 0, &test_byte, 1);
713 pm_runtime_idle(dev);
714 if (err) {
715 pm_runtime_disable(dev);
716 return -ENODEV;
717 }
718
719 dev_info(dev, "%u byte %s EEPROM, %s, %u bytes/write\n",
720 byte_len, client->name,
721 writable ? "writable" : "read-only", at24->write_max);
722
723 return 0;
724}
725
726static int at24_remove(struct i2c_client *client)
727{
728 pm_runtime_disable(&client->dev);
729 pm_runtime_set_suspended(&client->dev);
730
731 return 0;
732}
733
734static struct i2c_driver at24_driver = {
735 .driver = {
736 .name = "at24",
737 .of_match_table = at24_of_match,
738 .acpi_match_table = ACPI_PTR(at24_acpi_ids),
739 },
740 .probe_new = at24_probe,
741 .remove = at24_remove,
742 .id_table = at24_ids,
743};
744
745static int __init at24_init(void)
746{
747 if (!at24_io_limit) {
748 pr_err("at24: at24_io_limit must not be 0!\n");
749 return -EINVAL;
750 }
751
752 at24_io_limit = rounddown_pow_of_two(at24_io_limit);
753 return i2c_add_driver(&at24_driver);
754}
755module_init(at24_init);
756
757static void __exit at24_exit(void)
758{
759 i2c_del_driver(&at24_driver);
760}
761module_exit(at24_exit);
762
763MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
764MODULE_AUTHOR("David Brownell and Wolfram Sang");
765MODULE_LICENSE("GPL");
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/platform_data/at24.h>
27
28/*
29 * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
30 * Differences between different vendor product lines (like Atmel AT24C or
31 * MicroChip 24LC, etc) won't much matter for typical read/write access.
32 * There are also I2C RAM chips, likewise interchangeable. One example
33 * would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
34 *
35 * However, misconfiguration can lose data. "Set 16-bit memory address"
36 * to a part with 8-bit addressing will overwrite data. Writing with too
37 * big a page size also loses data. And it's not safe to assume that the
38 * conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
39 * uses 0x51, for just one example.
40 *
41 * Accordingly, explicit board-specific configuration data should be used
42 * in almost all cases. (One partial exception is an SMBus used to access
43 * "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
44 *
45 * So this driver uses "new style" I2C driver binding, expecting to be
46 * told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
47 * similar kernel-resident tables; or, configuration data coming from
48 * a bootloader.
49 *
50 * Other than binding model, current differences from "eeprom" driver are
51 * that this one handles write access and isn't restricted to 24c02 devices.
52 * It also handles larger devices (32 kbit and up) with two-byte addresses,
53 * which won't work on pure SMBus systems.
54 */
55
56struct at24_data {
57 struct at24_platform_data chip;
58 int use_smbus;
59 int use_smbus_write;
60
61 ssize_t (*read_func)(struct at24_data *, char *, unsigned int, size_t);
62 ssize_t (*write_func)(struct at24_data *,
63 const char *, unsigned int, size_t);
64
65 /*
66 * Lock protects against activities from other Linux tasks,
67 * but not from changes by other I2C masters.
68 */
69 struct mutex lock;
70
71 u8 *writebuf;
72 unsigned write_max;
73 unsigned num_addresses;
74
75 struct nvmem_config nvmem_config;
76 struct nvmem_device *nvmem;
77
78 /*
79 * Some chips tie up multiple I2C addresses; dummy devices reserve
80 * them for us, and we'll use them with SMBus calls.
81 */
82 struct i2c_client *client[];
83};
84
85/*
86 * This parameter is to help this driver avoid blocking other drivers out
87 * of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
88 * clock, one 256 byte read takes about 1/43 second which is excessive;
89 * but the 1/170 second it takes at 400 kHz may be quite reasonable; and
90 * at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
91 *
92 * This value is forced to be a power of two so that writes align on pages.
93 */
94static unsigned io_limit = 128;
95module_param(io_limit, uint, 0);
96MODULE_PARM_DESC(io_limit, "Maximum bytes per I/O (default 128)");
97
98/*
99 * Specs often allow 5 msec for a page write, sometimes 20 msec;
100 * it's important to recover from write timeouts.
101 */
102static unsigned write_timeout = 25;
103module_param(write_timeout, uint, 0);
104MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
105
106#define AT24_SIZE_BYTELEN 5
107#define AT24_SIZE_FLAGS 8
108
109#define AT24_BITMASK(x) (BIT(x) - 1)
110
111/* create non-zero magic value for given eeprom parameters */
112#define AT24_DEVICE_MAGIC(_len, _flags) \
113 ((1 << AT24_SIZE_FLAGS | (_flags)) \
114 << AT24_SIZE_BYTELEN | ilog2(_len))
115
116/*
117 * Both reads and writes fail if the previous write didn't complete yet. This
118 * macro loops a few times waiting at least long enough for one entire page
119 * write to work while making sure that at least one iteration is run before
120 * checking the break condition.
121 *
122 * It takes two parameters: a variable in which the future timeout in jiffies
123 * will be stored and a temporary variable holding the time of the last
124 * iteration of processing the request. Both should be unsigned integers
125 * holding at least 32 bits.
126 */
127#define loop_until_timeout(tout, op_time) \
128 for (tout = jiffies + msecs_to_jiffies(write_timeout), op_time = 0; \
129 op_time ? time_before(op_time, tout) : true; \
130 usleep_range(1000, 1500), op_time = jiffies)
131
132static const struct i2c_device_id at24_ids[] = {
133 /* needs 8 addresses as A0-A2 are ignored */
134 { "24c00", AT24_DEVICE_MAGIC(128 / 8, AT24_FLAG_TAKE8ADDR) },
135 /* old variants can't be handled with this generic entry! */
136 { "24c01", AT24_DEVICE_MAGIC(1024 / 8, 0) },
137 { "24cs01", AT24_DEVICE_MAGIC(16,
138 AT24_FLAG_SERIAL | AT24_FLAG_READONLY) },
139 { "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) },
140 { "24cs02", AT24_DEVICE_MAGIC(16,
141 AT24_FLAG_SERIAL | AT24_FLAG_READONLY) },
142 { "24mac402", AT24_DEVICE_MAGIC(48 / 8,
143 AT24_FLAG_MAC | AT24_FLAG_READONLY) },
144 { "24mac602", AT24_DEVICE_MAGIC(64 / 8,
145 AT24_FLAG_MAC | AT24_FLAG_READONLY) },
146 /* spd is a 24c02 in memory DIMMs */
147 { "spd", AT24_DEVICE_MAGIC(2048 / 8,
148 AT24_FLAG_READONLY | AT24_FLAG_IRUGO) },
149 { "24c04", AT24_DEVICE_MAGIC(4096 / 8, 0) },
150 { "24cs04", AT24_DEVICE_MAGIC(16,
151 AT24_FLAG_SERIAL | AT24_FLAG_READONLY) },
152 /* 24rf08 quirk is handled at i2c-core */
153 { "24c08", AT24_DEVICE_MAGIC(8192 / 8, 0) },
154 { "24cs08", AT24_DEVICE_MAGIC(16,
155 AT24_FLAG_SERIAL | AT24_FLAG_READONLY) },
156 { "24c16", AT24_DEVICE_MAGIC(16384 / 8, 0) },
157 { "24cs16", AT24_DEVICE_MAGIC(16,
158 AT24_FLAG_SERIAL | AT24_FLAG_READONLY) },
159 { "24c32", AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16) },
160 { "24cs32", AT24_DEVICE_MAGIC(16,
161 AT24_FLAG_ADDR16 |
162 AT24_FLAG_SERIAL |
163 AT24_FLAG_READONLY) },
164 { "24c64", AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16) },
165 { "24cs64", AT24_DEVICE_MAGIC(16,
166 AT24_FLAG_ADDR16 |
167 AT24_FLAG_SERIAL |
168 AT24_FLAG_READONLY) },
169 { "24c128", AT24_DEVICE_MAGIC(131072 / 8, AT24_FLAG_ADDR16) },
170 { "24c256", AT24_DEVICE_MAGIC(262144 / 8, AT24_FLAG_ADDR16) },
171 { "24c512", AT24_DEVICE_MAGIC(524288 / 8, AT24_FLAG_ADDR16) },
172 { "24c1024", AT24_DEVICE_MAGIC(1048576 / 8, AT24_FLAG_ADDR16) },
173 { "at24", 0 },
174 { /* END OF LIST */ }
175};
176MODULE_DEVICE_TABLE(i2c, at24_ids);
177
178static const struct acpi_device_id at24_acpi_ids[] = {
179 { "INT3499", AT24_DEVICE_MAGIC(8192 / 8, 0) },
180 { }
181};
182MODULE_DEVICE_TABLE(acpi, at24_acpi_ids);
183
184/*-------------------------------------------------------------------------*/
185
186/*
187 * This routine supports chips which consume multiple I2C addresses. It
188 * computes the addressing information to be used for a given r/w request.
189 * Assumes that sanity checks for offset happened at sysfs-layer.
190 *
191 * Slave address and byte offset derive from the offset. Always
192 * set the byte address; on a multi-master board, another master
193 * may have changed the chip's "current" address pointer.
194 *
195 * REVISIT some multi-address chips don't rollover page reads to
196 * the next slave address, so we may need to truncate the count.
197 * Those chips might need another quirk flag.
198 *
199 * If the real hardware used four adjacent 24c02 chips and that
200 * were misconfigured as one 24c08, that would be a similar effect:
201 * one "eeprom" file not four, but larger reads would fail when
202 * they crossed certain pages.
203 */
204static struct i2c_client *at24_translate_offset(struct at24_data *at24,
205 unsigned int *offset)
206{
207 unsigned i;
208
209 if (at24->chip.flags & AT24_FLAG_ADDR16) {
210 i = *offset >> 16;
211 *offset &= 0xffff;
212 } else {
213 i = *offset >> 8;
214 *offset &= 0xff;
215 }
216
217 return at24->client[i];
218}
219
220static ssize_t at24_eeprom_read_smbus(struct at24_data *at24, char *buf,
221 unsigned int offset, size_t count)
222{
223 unsigned long timeout, read_time;
224 struct i2c_client *client;
225 int status;
226
227 client = at24_translate_offset(at24, &offset);
228
229 if (count > io_limit)
230 count = io_limit;
231
232 /* Smaller eeproms can work given some SMBus extension calls */
233 if (count > I2C_SMBUS_BLOCK_MAX)
234 count = I2C_SMBUS_BLOCK_MAX;
235
236 loop_until_timeout(timeout, read_time) {
237 status = i2c_smbus_read_i2c_block_data_or_emulated(client,
238 offset,
239 count, buf);
240
241 dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
242 count, offset, status, jiffies);
243
244 if (status == count)
245 return count;
246 }
247
248 return -ETIMEDOUT;
249}
250
251static ssize_t at24_eeprom_read_i2c(struct at24_data *at24, char *buf,
252 unsigned int offset, size_t count)
253{
254 unsigned long timeout, read_time;
255 struct i2c_client *client;
256 struct i2c_msg msg[2];
257 int status, i;
258 u8 msgbuf[2];
259
260 memset(msg, 0, sizeof(msg));
261 client = at24_translate_offset(at24, &offset);
262
263 if (count > io_limit)
264 count = io_limit;
265
266 /*
267 * When we have a better choice than SMBus calls, use a combined I2C
268 * message. Write address; then read up to io_limit data bytes. Note
269 * that read page rollover helps us here (unlike writes). msgbuf is
270 * u8 and will cast to our needs.
271 */
272 i = 0;
273 if (at24->chip.flags & AT24_FLAG_ADDR16)
274 msgbuf[i++] = offset >> 8;
275 msgbuf[i++] = offset;
276
277 msg[0].addr = client->addr;
278 msg[0].buf = msgbuf;
279 msg[0].len = i;
280
281 msg[1].addr = client->addr;
282 msg[1].flags = I2C_M_RD;
283 msg[1].buf = buf;
284 msg[1].len = count;
285
286 loop_until_timeout(timeout, read_time) {
287 status = i2c_transfer(client->adapter, msg, 2);
288 if (status == 2)
289 status = count;
290
291 dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
292 count, offset, status, jiffies);
293
294 if (status == count)
295 return count;
296 }
297
298 return -ETIMEDOUT;
299}
300
301static ssize_t at24_eeprom_read_serial(struct at24_data *at24, char *buf,
302 unsigned int offset, size_t count)
303{
304 unsigned long timeout, read_time;
305 struct i2c_client *client;
306 struct i2c_msg msg[2];
307 u8 addrbuf[2];
308 int status;
309
310 client = at24_translate_offset(at24, &offset);
311
312 memset(msg, 0, sizeof(msg));
313 msg[0].addr = client->addr;
314 msg[0].buf = addrbuf;
315
316 /*
317 * The address pointer of the device is shared between the regular
318 * EEPROM array and the serial number block. The dummy write (part of
319 * the sequential read protocol) ensures the address pointer is reset
320 * to the desired position.
321 */
322 if (at24->chip.flags & AT24_FLAG_ADDR16) {
323 /*
324 * For 16 bit address pointers, the word address must contain
325 * a '10' sequence in bits 11 and 10 regardless of the
326 * intended position of the address pointer.
327 */
328 addrbuf[0] = 0x08;
329 addrbuf[1] = offset;
330 msg[0].len = 2;
331 } else {
332 /*
333 * Otherwise the word address must begin with a '10' sequence,
334 * regardless of the intended address.
335 */
336 addrbuf[0] = 0x80 + offset;
337 msg[0].len = 1;
338 }
339
340 msg[1].addr = client->addr;
341 msg[1].flags = I2C_M_RD;
342 msg[1].buf = buf;
343 msg[1].len = count;
344
345 loop_until_timeout(timeout, read_time) {
346 status = i2c_transfer(client->adapter, msg, 2);
347 if (status == 2)
348 return count;
349 }
350
351 return -ETIMEDOUT;
352}
353
354static ssize_t at24_eeprom_read_mac(struct at24_data *at24, char *buf,
355 unsigned int offset, size_t count)
356{
357 unsigned long timeout, read_time;
358 struct i2c_client *client;
359 struct i2c_msg msg[2];
360 u8 addrbuf[2];
361 int status;
362
363 client = at24_translate_offset(at24, &offset);
364
365 memset(msg, 0, sizeof(msg));
366 msg[0].addr = client->addr;
367 msg[0].buf = addrbuf;
368 addrbuf[0] = 0x90 + offset;
369 msg[0].len = 1;
370 msg[1].addr = client->addr;
371 msg[1].flags = I2C_M_RD;
372 msg[1].buf = buf;
373 msg[1].len = count;
374
375 loop_until_timeout(timeout, read_time) {
376 status = i2c_transfer(client->adapter, msg, 2);
377 if (status == 2)
378 return count;
379 }
380
381 return -ETIMEDOUT;
382}
383
384/*
385 * Note that if the hardware write-protect pin is pulled high, the whole
386 * chip is normally write protected. But there are plenty of product
387 * variants here, including OTP fuses and partial chip protect.
388 *
389 * We only use page mode writes; the alternative is sloooow. These routines
390 * write at most one page.
391 */
392
393static size_t at24_adjust_write_count(struct at24_data *at24,
394 unsigned int offset, size_t count)
395{
396 unsigned next_page;
397
398 /* write_max is at most a page */
399 if (count > at24->write_max)
400 count = at24->write_max;
401
402 /* Never roll over backwards, to the start of this page */
403 next_page = roundup(offset + 1, at24->chip.page_size);
404 if (offset + count > next_page)
405 count = next_page - offset;
406
407 return count;
408}
409
410static ssize_t at24_eeprom_write_smbus_block(struct at24_data *at24,
411 const char *buf,
412 unsigned int offset, size_t count)
413{
414 unsigned long timeout, write_time;
415 struct i2c_client *client;
416 ssize_t status = 0;
417
418 client = at24_translate_offset(at24, &offset);
419 count = at24_adjust_write_count(at24, offset, count);
420
421 loop_until_timeout(timeout, write_time) {
422 status = i2c_smbus_write_i2c_block_data(client,
423 offset, count, buf);
424 if (status == 0)
425 status = count;
426
427 dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n",
428 count, offset, status, jiffies);
429
430 if (status == count)
431 return count;
432 }
433
434 return -ETIMEDOUT;
435}
436
437static ssize_t at24_eeprom_write_smbus_byte(struct at24_data *at24,
438 const char *buf,
439 unsigned int offset, size_t count)
440{
441 unsigned long timeout, write_time;
442 struct i2c_client *client;
443 ssize_t status = 0;
444
445 client = at24_translate_offset(at24, &offset);
446
447 loop_until_timeout(timeout, write_time) {
448 status = i2c_smbus_write_byte_data(client, offset, buf[0]);
449 if (status == 0)
450 status = count;
451
452 dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n",
453 count, offset, status, jiffies);
454
455 if (status == count)
456 return count;
457 }
458
459 return -ETIMEDOUT;
460}
461
462static ssize_t at24_eeprom_write_i2c(struct at24_data *at24, const char *buf,
463 unsigned int offset, size_t count)
464{
465 unsigned long timeout, write_time;
466 struct i2c_client *client;
467 struct i2c_msg msg;
468 ssize_t status = 0;
469 int i = 0;
470
471 client = at24_translate_offset(at24, &offset);
472 count = at24_adjust_write_count(at24, offset, count);
473
474 msg.addr = client->addr;
475 msg.flags = 0;
476
477 /* msg.buf is u8 and casts will mask the values */
478 msg.buf = at24->writebuf;
479 if (at24->chip.flags & AT24_FLAG_ADDR16)
480 msg.buf[i++] = offset >> 8;
481
482 msg.buf[i++] = offset;
483 memcpy(&msg.buf[i], buf, count);
484 msg.len = i + count;
485
486 loop_until_timeout(timeout, write_time) {
487 status = i2c_transfer(client->adapter, &msg, 1);
488 if (status == 1)
489 status = count;
490
491 dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n",
492 count, offset, status, jiffies);
493
494 if (status == count)
495 return count;
496 }
497
498 return -ETIMEDOUT;
499}
500
501static int at24_read(void *priv, unsigned int off, void *val, size_t count)
502{
503 struct at24_data *at24 = priv;
504 char *buf = val;
505
506 if (unlikely(!count))
507 return count;
508
509 /*
510 * Read data from chip, protecting against concurrent updates
511 * from this host, but not from other I2C masters.
512 */
513 mutex_lock(&at24->lock);
514
515 while (count) {
516 int status;
517
518 status = at24->read_func(at24, buf, off, count);
519 if (status < 0) {
520 mutex_unlock(&at24->lock);
521 return status;
522 }
523 buf += status;
524 off += status;
525 count -= status;
526 }
527
528 mutex_unlock(&at24->lock);
529
530 return 0;
531}
532
533static int at24_write(void *priv, unsigned int off, void *val, size_t count)
534{
535 struct at24_data *at24 = priv;
536 char *buf = val;
537
538 if (unlikely(!count))
539 return -EINVAL;
540
541 /*
542 * Write data to chip, protecting against concurrent updates
543 * from this host, but not from other I2C masters.
544 */
545 mutex_lock(&at24->lock);
546
547 while (count) {
548 int status;
549
550 status = at24->write_func(at24, buf, off, count);
551 if (status < 0) {
552 mutex_unlock(&at24->lock);
553 return status;
554 }
555 buf += status;
556 off += status;
557 count -= status;
558 }
559
560 mutex_unlock(&at24->lock);
561
562 return 0;
563}
564
565#ifdef CONFIG_OF
566static void at24_get_ofdata(struct i2c_client *client,
567 struct at24_platform_data *chip)
568{
569 const __be32 *val;
570 struct device_node *node = client->dev.of_node;
571
572 if (node) {
573 if (of_get_property(node, "read-only", NULL))
574 chip->flags |= AT24_FLAG_READONLY;
575 val = of_get_property(node, "pagesize", NULL);
576 if (val)
577 chip->page_size = be32_to_cpup(val);
578 }
579}
580#else
581static void at24_get_ofdata(struct i2c_client *client,
582 struct at24_platform_data *chip)
583{ }
584#endif /* CONFIG_OF */
585
586static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
587{
588 struct at24_platform_data chip;
589 kernel_ulong_t magic = 0;
590 bool writable;
591 int use_smbus = 0;
592 int use_smbus_write = 0;
593 struct at24_data *at24;
594 int err;
595 unsigned i, num_addresses;
596 u8 test_byte;
597
598 if (client->dev.platform_data) {
599 chip = *(struct at24_platform_data *)client->dev.platform_data;
600 } else {
601 if (id) {
602 magic = id->driver_data;
603 } else {
604 const struct acpi_device_id *aid;
605
606 aid = acpi_match_device(at24_acpi_ids, &client->dev);
607 if (aid)
608 magic = aid->driver_data;
609 }
610 if (!magic)
611 return -ENODEV;
612
613 chip.byte_len = BIT(magic & AT24_BITMASK(AT24_SIZE_BYTELEN));
614 magic >>= AT24_SIZE_BYTELEN;
615 chip.flags = magic & AT24_BITMASK(AT24_SIZE_FLAGS);
616 /*
617 * This is slow, but we can't know all eeproms, so we better
618 * play safe. Specifying custom eeprom-types via platform_data
619 * is recommended anyhow.
620 */
621 chip.page_size = 1;
622
623 /* update chipdata if OF is present */
624 at24_get_ofdata(client, &chip);
625
626 chip.setup = NULL;
627 chip.context = NULL;
628 }
629
630 if (!is_power_of_2(chip.byte_len))
631 dev_warn(&client->dev,
632 "byte_len looks suspicious (no power of 2)!\n");
633 if (!chip.page_size) {
634 dev_err(&client->dev, "page_size must not be 0!\n");
635 return -EINVAL;
636 }
637 if (!is_power_of_2(chip.page_size))
638 dev_warn(&client->dev,
639 "page_size looks suspicious (no power of 2)!\n");
640
641 /* Use I2C operations unless we're stuck with SMBus extensions. */
642 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
643 if (chip.flags & AT24_FLAG_ADDR16)
644 return -EPFNOSUPPORT;
645
646 if (i2c_check_functionality(client->adapter,
647 I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
648 use_smbus = I2C_SMBUS_I2C_BLOCK_DATA;
649 } else if (i2c_check_functionality(client->adapter,
650 I2C_FUNC_SMBUS_READ_WORD_DATA)) {
651 use_smbus = I2C_SMBUS_WORD_DATA;
652 } else if (i2c_check_functionality(client->adapter,
653 I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
654 use_smbus = I2C_SMBUS_BYTE_DATA;
655 } else {
656 return -EPFNOSUPPORT;
657 }
658
659 if (i2c_check_functionality(client->adapter,
660 I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
661 use_smbus_write = I2C_SMBUS_I2C_BLOCK_DATA;
662 } else if (i2c_check_functionality(client->adapter,
663 I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) {
664 use_smbus_write = I2C_SMBUS_BYTE_DATA;
665 chip.page_size = 1;
666 }
667 }
668
669 if (chip.flags & AT24_FLAG_TAKE8ADDR)
670 num_addresses = 8;
671 else
672 num_addresses = DIV_ROUND_UP(chip.byte_len,
673 (chip.flags & AT24_FLAG_ADDR16) ? 65536 : 256);
674
675 at24 = devm_kzalloc(&client->dev, sizeof(struct at24_data) +
676 num_addresses * sizeof(struct i2c_client *), GFP_KERNEL);
677 if (!at24)
678 return -ENOMEM;
679
680 mutex_init(&at24->lock);
681 at24->use_smbus = use_smbus;
682 at24->use_smbus_write = use_smbus_write;
683 at24->chip = chip;
684 at24->num_addresses = num_addresses;
685
686 if ((chip.flags & AT24_FLAG_SERIAL) && (chip.flags & AT24_FLAG_MAC)) {
687 dev_err(&client->dev,
688 "invalid device data - cannot have both AT24_FLAG_SERIAL & AT24_FLAG_MAC.");
689 return -EINVAL;
690 }
691
692 if (chip.flags & AT24_FLAG_SERIAL) {
693 at24->read_func = at24_eeprom_read_serial;
694 } else if (chip.flags & AT24_FLAG_MAC) {
695 at24->read_func = at24_eeprom_read_mac;
696 } else {
697 at24->read_func = at24->use_smbus ? at24_eeprom_read_smbus
698 : at24_eeprom_read_i2c;
699 }
700
701 if (at24->use_smbus) {
702 if (at24->use_smbus_write == I2C_SMBUS_I2C_BLOCK_DATA)
703 at24->write_func = at24_eeprom_write_smbus_block;
704 else
705 at24->write_func = at24_eeprom_write_smbus_byte;
706 } else {
707 at24->write_func = at24_eeprom_write_i2c;
708 }
709
710 writable = !(chip.flags & AT24_FLAG_READONLY);
711 if (writable) {
712 if (!use_smbus || use_smbus_write) {
713
714 unsigned write_max = chip.page_size;
715
716 if (write_max > io_limit)
717 write_max = io_limit;
718 if (use_smbus && write_max > I2C_SMBUS_BLOCK_MAX)
719 write_max = I2C_SMBUS_BLOCK_MAX;
720 at24->write_max = write_max;
721
722 /* buffer (data + address at the beginning) */
723 at24->writebuf = devm_kzalloc(&client->dev,
724 write_max + 2, GFP_KERNEL);
725 if (!at24->writebuf)
726 return -ENOMEM;
727 } else {
728 dev_warn(&client->dev,
729 "cannot write due to controller restrictions.");
730 }
731 }
732
733 at24->client[0] = client;
734
735 /* use dummy devices for multiple-address chips */
736 for (i = 1; i < num_addresses; i++) {
737 at24->client[i] = i2c_new_dummy(client->adapter,
738 client->addr + i);
739 if (!at24->client[i]) {
740 dev_err(&client->dev, "address 0x%02x unavailable\n",
741 client->addr + i);
742 err = -EADDRINUSE;
743 goto err_clients;
744 }
745 }
746
747 i2c_set_clientdata(client, at24);
748
749 /*
750 * Perform a one-byte test read to verify that the
751 * chip is functional.
752 */
753 err = at24_read(at24, 0, &test_byte, 1);
754 if (err) {
755 err = -ENODEV;
756 goto err_clients;
757 }
758
759 at24->nvmem_config.name = dev_name(&client->dev);
760 at24->nvmem_config.dev = &client->dev;
761 at24->nvmem_config.read_only = !writable;
762 at24->nvmem_config.root_only = true;
763 at24->nvmem_config.owner = THIS_MODULE;
764 at24->nvmem_config.compat = true;
765 at24->nvmem_config.base_dev = &client->dev;
766 at24->nvmem_config.reg_read = at24_read;
767 at24->nvmem_config.reg_write = at24_write;
768 at24->nvmem_config.priv = at24;
769 at24->nvmem_config.stride = 4;
770 at24->nvmem_config.word_size = 1;
771 at24->nvmem_config.size = chip.byte_len;
772
773 at24->nvmem = nvmem_register(&at24->nvmem_config);
774
775 if (IS_ERR(at24->nvmem)) {
776 err = PTR_ERR(at24->nvmem);
777 goto err_clients;
778 }
779
780 dev_info(&client->dev, "%u byte %s EEPROM, %s, %u bytes/write\n",
781 chip.byte_len, client->name,
782 writable ? "writable" : "read-only", at24->write_max);
783 if (use_smbus == I2C_SMBUS_WORD_DATA ||
784 use_smbus == I2C_SMBUS_BYTE_DATA) {
785 dev_notice(&client->dev, "Falling back to %s reads, "
786 "performance will suffer\n", use_smbus ==
787 I2C_SMBUS_WORD_DATA ? "word" : "byte");
788 }
789
790 /* export data to kernel code */
791 if (chip.setup)
792 chip.setup(at24->nvmem, chip.context);
793
794 return 0;
795
796err_clients:
797 for (i = 1; i < num_addresses; i++)
798 if (at24->client[i])
799 i2c_unregister_device(at24->client[i]);
800
801 return err;
802}
803
804static int at24_remove(struct i2c_client *client)
805{
806 struct at24_data *at24;
807 int i;
808
809 at24 = i2c_get_clientdata(client);
810
811 nvmem_unregister(at24->nvmem);
812
813 for (i = 1; i < at24->num_addresses; i++)
814 i2c_unregister_device(at24->client[i]);
815
816 return 0;
817}
818
819/*-------------------------------------------------------------------------*/
820
821static struct i2c_driver at24_driver = {
822 .driver = {
823 .name = "at24",
824 .acpi_match_table = ACPI_PTR(at24_acpi_ids),
825 },
826 .probe = at24_probe,
827 .remove = at24_remove,
828 .id_table = at24_ids,
829};
830
831static int __init at24_init(void)
832{
833 if (!io_limit) {
834 pr_err("at24: io_limit must not be 0!\n");
835 return -EINVAL;
836 }
837
838 io_limit = rounddown_pow_of_two(io_limit);
839 return i2c_add_driver(&at24_driver);
840}
841module_init(at24_init);
842
843static void __exit at24_exit(void)
844{
845 i2c_del_driver(&at24_driver);
846}
847module_exit(at24_exit);
848
849MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
850MODULE_AUTHOR("David Brownell and Wolfram Sang");
851MODULE_LICENSE("GPL");