1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * at24.c - handle most I2C EEPROMs
4 *
5 * Copyright (C) 2005-2007 David Brownell
6 * Copyright (C) 2008 Wolfram Sang, Pengutronix
7 */
8
9 #include <linux/acpi.h>
10 #include <linux/bitops.h>
11 #include <linux/capability.h>
12 #include <linux/delay.h>
13 #include <linux/i2c.h>
14 #include <linux/init.h>
15 #include <linux/jiffies.h>
16 #include <linux/kernel.h>
17 #include <linux/mod_devicetable.h>
18 #include <linux/module.h>
19 #include <linux/mutex.h>
20 #include <linux/nvmem-provider.h>
21 #include <linux/of_device.h>
22 #include <linux/pm_runtime.h>
23 #include <linux/property.h>
24 #include <linux/regmap.h>
25 #include <linux/regulator/consumer.h>
26 #include <linux/slab.h>
27
28 /* Address pointer is 16 bit. */
29 #define AT24_FLAG_ADDR16 BIT(7)
30 /* sysfs-entry will be read-only. */
31 #define AT24_FLAG_READONLY BIT(6)
32 /* sysfs-entry will be world-readable. */
33 #define AT24_FLAG_IRUGO BIT(5)
34 /* Take always 8 addresses (24c00). */
35 #define AT24_FLAG_TAKE8ADDR BIT(4)
36 /* Factory-programmed serial number. */
37 #define AT24_FLAG_SERIAL BIT(3)
38 /* Factory-programmed mac address. */
39 #define AT24_FLAG_MAC BIT(2)
40 /* Does not auto-rollover reads to the next slave address. */
41 #define AT24_FLAG_NO_RDROL BIT(1)
42
43 /*
44 * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
45 * Differences between different vendor product lines (like Atmel AT24C or
46 * MicroChip 24LC, etc) won't much matter for typical read/write access.
47 * There are also I2C RAM chips, likewise interchangeable. One example
48 * would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
49 *
50 * However, misconfiguration can lose data. "Set 16-bit memory address"
51 * to a part with 8-bit addressing will overwrite data. Writing with too
52 * big a page size also loses data. And it's not safe to assume that the
53 * conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
54 * uses 0x51, for just one example.
55 *
56 * Accordingly, explicit board-specific configuration data should be used
57 * in almost all cases. (One partial exception is an SMBus used to access
58 * "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
59 *
60 * So this driver uses "new style" I2C driver binding, expecting to be
61 * told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
62 * similar kernel-resident tables; or, configuration data coming from
63 * a bootloader.
64 *
65 * Other than binding model, current differences from "eeprom" driver are
66 * that this one handles write access and isn't restricted to 24c02 devices.
67 * It also handles larger devices (32 kbit and up) with two-byte addresses,
68 * which won't work on pure SMBus systems.
69 */
70
71 struct at24_client {
72 struct i2c_client *client;
73 struct regmap *regmap;
74 };
75
76 struct at24_data {
77 /*
78 * Lock protects against activities from other Linux tasks,
79 * but not from changes by other I2C masters.
80 */
81 struct mutex lock;
82
83 unsigned int write_max;
84 unsigned int num_addresses;
85 unsigned int offset_adj;
86
87 u32 byte_len;
88 u16 page_size;
89 u8 flags;
90
91 struct nvmem_device *nvmem;
92 struct regulator *vcc_reg;
93 void (*read_post)(unsigned int off, char *buf, size_t count);
94
95 /*
96 * Some chips tie up multiple I2C addresses; dummy devices reserve
97 * them for us, and we'll use them with SMBus calls.
98 */
99 struct at24_client client[];
100 };
101
102 /*
103 * This parameter is to help this driver avoid blocking other drivers out
104 * of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
105 * clock, one 256 byte read takes about 1/43 second which is excessive;
106 * but the 1/170 second it takes at 400 kHz may be quite reasonable; and
107 * at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
108 *
109 * This value is forced to be a power of two so that writes align on pages.
110 */
111 static unsigned int at24_io_limit = 128;
112 module_param_named(io_limit, at24_io_limit, uint, 0);
113 MODULE_PARM_DESC(at24_io_limit, "Maximum bytes per I/O (default 128)");
114
115 /*
116 * Specs often allow 5 msec for a page write, sometimes 20 msec;
117 * it's important to recover from write timeouts.
118 */
119 static unsigned int at24_write_timeout = 25;
120 module_param_named(write_timeout, at24_write_timeout, uint, 0);
121 MODULE_PARM_DESC(at24_write_timeout, "Time (in ms) to try writes (default 25)");
122
123 struct at24_chip_data {
124 u32 byte_len;
125 u8 flags;
126 void (*read_post)(unsigned int off, char *buf, size_t count);
127 };
128
129 #define AT24_CHIP_DATA(_name, _len, _flags) \
130 static const struct at24_chip_data _name = { \
131 .byte_len = _len, .flags = _flags, \
132 }
133
134 #define AT24_CHIP_DATA_CB(_name, _len, _flags, _read_post) \
135 static const struct at24_chip_data _name = { \
136 .byte_len = _len, .flags = _flags, \
137 .read_post = _read_post, \
138 }
139
at24_read_post_vaio(unsigned int off,char * buf,size_t count)140 static void at24_read_post_vaio(unsigned int off, char *buf, size_t count)
141 {
142 int i;
143
144 if (capable(CAP_SYS_ADMIN))
145 return;
146
147 /*
148 * Hide VAIO private settings to regular users:
149 * - BIOS passwords: bytes 0x00 to 0x0f
150 * - UUID: bytes 0x10 to 0x1f
151 * - Serial number: 0xc0 to 0xdf
152 */
153 for (i = 0; i < count; i++) {
154 if ((off + i <= 0x1f) ||
155 (off + i >= 0xc0 && off + i <= 0xdf))
156 buf[i] = 0;
157 }
158 }
159
160 /* needs 8 addresses as A0-A2 are ignored */
161 AT24_CHIP_DATA(at24_data_24c00, 128 / 8, AT24_FLAG_TAKE8ADDR);
162 /* old variants can't be handled with this generic entry! */
163 AT24_CHIP_DATA(at24_data_24c01, 1024 / 8, 0);
164 AT24_CHIP_DATA(at24_data_24cs01, 16,
165 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
166 AT24_CHIP_DATA(at24_data_24c02, 2048 / 8, 0);
167 AT24_CHIP_DATA(at24_data_24cs02, 16,
168 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
169 AT24_CHIP_DATA(at24_data_24mac402, 48 / 8,
170 AT24_FLAG_MAC | AT24_FLAG_READONLY);
171 AT24_CHIP_DATA(at24_data_24mac602, 64 / 8,
172 AT24_FLAG_MAC | AT24_FLAG_READONLY);
173 /* spd is a 24c02 in memory DIMMs */
174 AT24_CHIP_DATA(at24_data_spd, 2048 / 8,
175 AT24_FLAG_READONLY | AT24_FLAG_IRUGO);
176 /* 24c02_vaio is a 24c02 on some Sony laptops */
177 AT24_CHIP_DATA_CB(at24_data_24c02_vaio, 2048 / 8,
178 AT24_FLAG_READONLY | AT24_FLAG_IRUGO,
179 at24_read_post_vaio);
180 AT24_CHIP_DATA(at24_data_24c04, 4096 / 8, 0);
181 AT24_CHIP_DATA(at24_data_24cs04, 16,
182 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
183 /* 24rf08 quirk is handled at i2c-core */
184 AT24_CHIP_DATA(at24_data_24c08, 8192 / 8, 0);
185 AT24_CHIP_DATA(at24_data_24cs08, 16,
186 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
187 AT24_CHIP_DATA(at24_data_24c16, 16384 / 8, 0);
188 AT24_CHIP_DATA(at24_data_24cs16, 16,
189 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
190 AT24_CHIP_DATA(at24_data_24c32, 32768 / 8, AT24_FLAG_ADDR16);
191 AT24_CHIP_DATA(at24_data_24cs32, 16,
192 AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
193 AT24_CHIP_DATA(at24_data_24c64, 65536 / 8, AT24_FLAG_ADDR16);
194 AT24_CHIP_DATA(at24_data_24cs64, 16,
195 AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
196 AT24_CHIP_DATA(at24_data_24c128, 131072 / 8, AT24_FLAG_ADDR16);
197 AT24_CHIP_DATA(at24_data_24c256, 262144 / 8, AT24_FLAG_ADDR16);
198 AT24_CHIP_DATA(at24_data_24c512, 524288 / 8, AT24_FLAG_ADDR16);
199 AT24_CHIP_DATA(at24_data_24c1024, 1048576 / 8, AT24_FLAG_ADDR16);
200 AT24_CHIP_DATA(at24_data_24c2048, 2097152 / 8, AT24_FLAG_ADDR16);
201 /* identical to 24c08 ? */
202 AT24_CHIP_DATA(at24_data_INT3499, 8192 / 8, 0);
203
204 static const struct i2c_device_id at24_ids[] = {
205 { "24c00", (kernel_ulong_t)&at24_data_24c00 },
206 { "24c01", (kernel_ulong_t)&at24_data_24c01 },
207 { "24cs01", (kernel_ulong_t)&at24_data_24cs01 },
208 { "24c02", (kernel_ulong_t)&at24_data_24c02 },
209 { "24cs02", (kernel_ulong_t)&at24_data_24cs02 },
210 { "24mac402", (kernel_ulong_t)&at24_data_24mac402 },
211 { "24mac602", (kernel_ulong_t)&at24_data_24mac602 },
212 { "spd", (kernel_ulong_t)&at24_data_spd },
213 { "24c02-vaio", (kernel_ulong_t)&at24_data_24c02_vaio },
214 { "24c04", (kernel_ulong_t)&at24_data_24c04 },
215 { "24cs04", (kernel_ulong_t)&at24_data_24cs04 },
216 { "24c08", (kernel_ulong_t)&at24_data_24c08 },
217 { "24cs08", (kernel_ulong_t)&at24_data_24cs08 },
218 { "24c16", (kernel_ulong_t)&at24_data_24c16 },
219 { "24cs16", (kernel_ulong_t)&at24_data_24cs16 },
220 { "24c32", (kernel_ulong_t)&at24_data_24c32 },
221 { "24cs32", (kernel_ulong_t)&at24_data_24cs32 },
222 { "24c64", (kernel_ulong_t)&at24_data_24c64 },
223 { "24cs64", (kernel_ulong_t)&at24_data_24cs64 },
224 { "24c128", (kernel_ulong_t)&at24_data_24c128 },
225 { "24c256", (kernel_ulong_t)&at24_data_24c256 },
226 { "24c512", (kernel_ulong_t)&at24_data_24c512 },
227 { "24c1024", (kernel_ulong_t)&at24_data_24c1024 },
228 { "24c2048", (kernel_ulong_t)&at24_data_24c2048 },
229 { "at24", 0 },
230 { /* END OF LIST */ }
231 };
232 MODULE_DEVICE_TABLE(i2c, at24_ids);
233
234 static const struct of_device_id at24_of_match[] = {
235 { .compatible = "atmel,24c00", .data = &at24_data_24c00 },
236 { .compatible = "atmel,24c01", .data = &at24_data_24c01 },
237 { .compatible = "atmel,24cs01", .data = &at24_data_24cs01 },
238 { .compatible = "atmel,24c02", .data = &at24_data_24c02 },
239 { .compatible = "atmel,24cs02", .data = &at24_data_24cs02 },
240 { .compatible = "atmel,24mac402", .data = &at24_data_24mac402 },
241 { .compatible = "atmel,24mac602", .data = &at24_data_24mac602 },
242 { .compatible = "atmel,spd", .data = &at24_data_spd },
243 { .compatible = "atmel,24c04", .data = &at24_data_24c04 },
244 { .compatible = "atmel,24cs04", .data = &at24_data_24cs04 },
245 { .compatible = "atmel,24c08", .data = &at24_data_24c08 },
246 { .compatible = "atmel,24cs08", .data = &at24_data_24cs08 },
247 { .compatible = "atmel,24c16", .data = &at24_data_24c16 },
248 { .compatible = "atmel,24cs16", .data = &at24_data_24cs16 },
249 { .compatible = "atmel,24c32", .data = &at24_data_24c32 },
250 { .compatible = "atmel,24cs32", .data = &at24_data_24cs32 },
251 { .compatible = "atmel,24c64", .data = &at24_data_24c64 },
252 { .compatible = "atmel,24cs64", .data = &at24_data_24cs64 },
253 { .compatible = "atmel,24c128", .data = &at24_data_24c128 },
254 { .compatible = "atmel,24c256", .data = &at24_data_24c256 },
255 { .compatible = "atmel,24c512", .data = &at24_data_24c512 },
256 { .compatible = "atmel,24c1024", .data = &at24_data_24c1024 },
257 { .compatible = "atmel,24c2048", .data = &at24_data_24c2048 },
258 { /* END OF LIST */ },
259 };
260 MODULE_DEVICE_TABLE(of, at24_of_match);
261
262 static const struct acpi_device_id __maybe_unused at24_acpi_ids[] = {
263 { "INT3499", (kernel_ulong_t)&at24_data_INT3499 },
264 { "TPF0001", (kernel_ulong_t)&at24_data_24c1024 },
265 { /* END OF LIST */ }
266 };
267 MODULE_DEVICE_TABLE(acpi, at24_acpi_ids);
268
269 /*
270 * This routine supports chips which consume multiple I2C addresses. It
271 * computes the addressing information to be used for a given r/w request.
272 * Assumes that sanity checks for offset happened at sysfs-layer.
273 *
274 * Slave address and byte offset derive from the offset. Always
275 * set the byte address; on a multi-master board, another master
276 * may have changed the chip's "current" address pointer.
277 */
at24_translate_offset(struct at24_data * at24,unsigned int * offset)278 static struct at24_client *at24_translate_offset(struct at24_data *at24,
279 unsigned int *offset)
280 {
281 unsigned int i;
282
283 if (at24->flags & AT24_FLAG_ADDR16) {
284 i = *offset >> 16;
285 *offset &= 0xffff;
286 } else {
287 i = *offset >> 8;
288 *offset &= 0xff;
289 }
290
291 return &at24->client[i];
292 }
293
at24_base_client_dev(struct at24_data * at24)294 static struct device *at24_base_client_dev(struct at24_data *at24)
295 {
296 return &at24->client[0].client->dev;
297 }
298
at24_adjust_read_count(struct at24_data * at24,unsigned int offset,size_t count)299 static size_t at24_adjust_read_count(struct at24_data *at24,
300 unsigned int offset, size_t count)
301 {
302 unsigned int bits;
303 size_t remainder;
304
305 /*
306 * In case of multi-address chips that don't rollover reads to
307 * the next slave address: truncate the count to the slave boundary,
308 * so that the read never straddles slaves.
309 */
310 if (at24->flags & AT24_FLAG_NO_RDROL) {
311 bits = (at24->flags & AT24_FLAG_ADDR16) ? 16 : 8;
312 remainder = BIT(bits) - offset;
313 if (count > remainder)
314 count = remainder;
315 }
316
317 if (count > at24_io_limit)
318 count = at24_io_limit;
319
320 return count;
321 }
322
at24_regmap_read(struct at24_data * at24,char * buf,unsigned int offset,size_t count)323 static ssize_t at24_regmap_read(struct at24_data *at24, char *buf,
324 unsigned int offset, size_t count)
325 {
326 unsigned long timeout, read_time;
327 struct at24_client *at24_client;
328 struct i2c_client *client;
329 struct regmap *regmap;
330 int ret;
331
332 at24_client = at24_translate_offset(at24, &offset);
333 regmap = at24_client->regmap;
334 client = at24_client->client;
335 count = at24_adjust_read_count(at24, offset, count);
336
337 /* adjust offset for mac and serial read ops */
338 offset += at24->offset_adj;
339
340 timeout = jiffies + msecs_to_jiffies(at24_write_timeout);
341 do {
342 /*
343 * The timestamp shall be taken before the actual operation
344 * to avoid a premature timeout in case of high CPU load.
345 */
346 read_time = jiffies;
347
348 ret = regmap_bulk_read(regmap, offset, buf, count);
349 dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
350 count, offset, ret, jiffies);
351 if (!ret)
352 return count;
353
354 usleep_range(1000, 1500);
355 } while (time_before(read_time, timeout));
356
357 return -ETIMEDOUT;
358 }
359
360 /*
361 * Note that if the hardware write-protect pin is pulled high, the whole
362 * chip is normally write protected. But there are plenty of product
363 * variants here, including OTP fuses and partial chip protect.
364 *
365 * We only use page mode writes; the alternative is sloooow. These routines
366 * write at most one page.
367 */
368
at24_adjust_write_count(struct at24_data * at24,unsigned int offset,size_t count)369 static size_t at24_adjust_write_count(struct at24_data *at24,
370 unsigned int offset, size_t count)
371 {
372 unsigned int next_page;
373
374 /* write_max is at most a page */
375 if (count > at24->write_max)
376 count = at24->write_max;
377
378 /* Never roll over backwards, to the start of this page */
379 next_page = roundup(offset + 1, at24->page_size);
380 if (offset + count > next_page)
381 count = next_page - offset;
382
383 return count;
384 }
385
at24_regmap_write(struct at24_data * at24,const char * buf,unsigned int offset,size_t count)386 static ssize_t at24_regmap_write(struct at24_data *at24, const char *buf,
387 unsigned int offset, size_t count)
388 {
389 unsigned long timeout, write_time;
390 struct at24_client *at24_client;
391 struct i2c_client *client;
392 struct regmap *regmap;
393 int ret;
394
395 at24_client = at24_translate_offset(at24, &offset);
396 regmap = at24_client->regmap;
397 client = at24_client->client;
398 count = at24_adjust_write_count(at24, offset, count);
399 timeout = jiffies + msecs_to_jiffies(at24_write_timeout);
400
401 do {
402 /*
403 * The timestamp shall be taken before the actual operation
404 * to avoid a premature timeout in case of high CPU load.
405 */
406 write_time = jiffies;
407
408 ret = regmap_bulk_write(regmap, offset, buf, count);
409 dev_dbg(&client->dev, "write %zu@%d --> %d (%ld)\n",
410 count, offset, ret, jiffies);
411 if (!ret)
412 return count;
413
414 usleep_range(1000, 1500);
415 } while (time_before(write_time, timeout));
416
417 return -ETIMEDOUT;
418 }
419
at24_read(void * priv,unsigned int off,void * val,size_t count)420 static int at24_read(void *priv, unsigned int off, void *val, size_t count)
421 {
422 struct at24_data *at24;
423 struct device *dev;
424 char *buf = val;
425 int i, ret;
426
427 at24 = priv;
428 dev = at24_base_client_dev(at24);
429
430 if (unlikely(!count))
431 return count;
432
433 if (off + count > at24->byte_len)
434 return -EINVAL;
435
436 ret = pm_runtime_get_sync(dev);
437 if (ret < 0) {
438 pm_runtime_put_noidle(dev);
439 return ret;
440 }
441
442 /*
443 * Read data from chip, protecting against concurrent updates
444 * from this host, but not from other I2C masters.
445 */
446 mutex_lock(&at24->lock);
447
448 for (i = 0; count; i += ret, count -= ret) {
449 ret = at24_regmap_read(at24, buf + i, off + i, count);
450 if (ret < 0) {
451 mutex_unlock(&at24->lock);
452 pm_runtime_put(dev);
453 return ret;
454 }
455 }
456
457 mutex_unlock(&at24->lock);
458
459 pm_runtime_put(dev);
460
461 if (unlikely(at24->read_post))
462 at24->read_post(off, buf, i);
463
464 return 0;
465 }
466
at24_write(void * priv,unsigned int off,void * val,size_t count)467 static int at24_write(void *priv, unsigned int off, void *val, size_t count)
468 {
469 struct at24_data *at24;
470 struct device *dev;
471 char *buf = val;
472 int ret;
473
474 at24 = priv;
475 dev = at24_base_client_dev(at24);
476
477 if (unlikely(!count))
478 return -EINVAL;
479
480 if (off + count > at24->byte_len)
481 return -EINVAL;
482
483 ret = pm_runtime_get_sync(dev);
484 if (ret < 0) {
485 pm_runtime_put_noidle(dev);
486 return ret;
487 }
488
489 /*
490 * Write data to chip, protecting against concurrent updates
491 * from this host, but not from other I2C masters.
492 */
493 mutex_lock(&at24->lock);
494
495 while (count) {
496 ret = at24_regmap_write(at24, buf, off, count);
497 if (ret < 0) {
498 mutex_unlock(&at24->lock);
499 pm_runtime_put(dev);
500 return ret;
501 }
502 buf += ret;
503 off += ret;
504 count -= ret;
505 }
506
507 mutex_unlock(&at24->lock);
508
509 pm_runtime_put(dev);
510
511 return 0;
512 }
513
at24_get_chip_data(struct device * dev)514 static const struct at24_chip_data *at24_get_chip_data(struct device *dev)
515 {
516 struct device_node *of_node = dev->of_node;
517 const struct at24_chip_data *cdata;
518 const struct i2c_device_id *id;
519
520 id = i2c_match_id(at24_ids, to_i2c_client(dev));
521
522 /*
523 * The I2C core allows OF nodes compatibles to match against the
524 * I2C device ID table as a fallback, so check not only if an OF
525 * node is present but also if it matches an OF device ID entry.
526 */
527 if (of_node && of_match_device(at24_of_match, dev))
528 cdata = of_device_get_match_data(dev);
529 else if (id)
530 cdata = (void *)id->driver_data;
531 else
532 cdata = acpi_device_get_match_data(dev);
533
534 if (!cdata)
535 return ERR_PTR(-ENODEV);
536
537 return cdata;
538 }
539
at24_make_dummy_client(struct at24_data * at24,unsigned int index,struct regmap_config * regmap_config)540 static int at24_make_dummy_client(struct at24_data *at24, unsigned int index,
541 struct regmap_config *regmap_config)
542 {
543 struct i2c_client *base_client, *dummy_client;
544 struct regmap *regmap;
545 struct device *dev;
546
547 base_client = at24->client[0].client;
548 dev = &base_client->dev;
549
550 dummy_client = devm_i2c_new_dummy_device(dev, base_client->adapter,
551 base_client->addr + index);
552 if (IS_ERR(dummy_client))
553 return PTR_ERR(dummy_client);
554
555 regmap = devm_regmap_init_i2c(dummy_client, regmap_config);
556 if (IS_ERR(regmap))
557 return PTR_ERR(regmap);
558
559 at24->client[index].client = dummy_client;
560 at24->client[index].regmap = regmap;
561
562 return 0;
563 }
564
at24_get_offset_adj(u8 flags,unsigned int byte_len)565 static unsigned int at24_get_offset_adj(u8 flags, unsigned int byte_len)
566 {
567 if (flags & AT24_FLAG_MAC) {
568 /* EUI-48 starts from 0x9a, EUI-64 from 0x98 */
569 return 0xa0 - byte_len;
570 } else if (flags & AT24_FLAG_SERIAL && flags & AT24_FLAG_ADDR16) {
571 /*
572 * For 16 bit address pointers, the word address must contain
573 * a '10' sequence in bits 11 and 10 regardless of the
574 * intended position of the address pointer.
575 */
576 return 0x0800;
577 } else if (flags & AT24_FLAG_SERIAL) {
578 /*
579 * Otherwise the word address must begin with a '10' sequence,
580 * regardless of the intended address.
581 */
582 return 0x0080;
583 } else {
584 return 0;
585 }
586 }
587
at24_probe(struct i2c_client * client)588 static int at24_probe(struct i2c_client *client)
589 {
590 struct regmap_config regmap_config = { };
591 struct nvmem_config nvmem_config = { };
592 u32 byte_len, page_size, flags, addrw;
593 const struct at24_chip_data *cdata;
594 struct device *dev = &client->dev;
595 bool i2c_fn_i2c, i2c_fn_block;
596 unsigned int i, num_addresses;
597 struct at24_data *at24;
598 struct regmap *regmap;
599 bool writable;
600 u8 test_byte;
601 int err;
602
603 i2c_fn_i2c = i2c_check_functionality(client->adapter, I2C_FUNC_I2C);
604 i2c_fn_block = i2c_check_functionality(client->adapter,
605 I2C_FUNC_SMBUS_WRITE_I2C_BLOCK);
606
607 cdata = at24_get_chip_data(dev);
608 if (IS_ERR(cdata))
609 return PTR_ERR(cdata);
610
611 err = device_property_read_u32(dev, "pagesize", &page_size);
612 if (err)
613 /*
614 * This is slow, but we can't know all eeproms, so we better
615 * play safe. Specifying custom eeprom-types via device tree
616 * or properties is recommended anyhow.
617 */
618 page_size = 1;
619
620 flags = cdata->flags;
621 if (device_property_present(dev, "read-only"))
622 flags |= AT24_FLAG_READONLY;
623 if (device_property_present(dev, "no-read-rollover"))
624 flags |= AT24_FLAG_NO_RDROL;
625
626 err = device_property_read_u32(dev, "address-width", &addrw);
627 if (!err) {
628 switch (addrw) {
629 case 8:
630 if (flags & AT24_FLAG_ADDR16)
631 dev_warn(dev,
632 "Override address width to be 8, while default is 16\n");
633 flags &= ~AT24_FLAG_ADDR16;
634 break;
635 case 16:
636 flags |= AT24_FLAG_ADDR16;
637 break;
638 default:
639 dev_warn(dev, "Bad \"address-width\" property: %u\n",
640 addrw);
641 }
642 }
643
644 err = device_property_read_u32(dev, "size", &byte_len);
645 if (err)
646 byte_len = cdata->byte_len;
647
648 if (!i2c_fn_i2c && !i2c_fn_block)
649 page_size = 1;
650
651 if (!page_size) {
652 dev_err(dev, "page_size must not be 0!\n");
653 return -EINVAL;
654 }
655
656 if (!is_power_of_2(page_size))
657 dev_warn(dev, "page_size looks suspicious (no power of 2)!\n");
658
659 err = device_property_read_u32(dev, "num-addresses", &num_addresses);
660 if (err) {
661 if (flags & AT24_FLAG_TAKE8ADDR)
662 num_addresses = 8;
663 else
664 num_addresses = DIV_ROUND_UP(byte_len,
665 (flags & AT24_FLAG_ADDR16) ? 65536 : 256);
666 }
667
668 if ((flags & AT24_FLAG_SERIAL) && (flags & AT24_FLAG_MAC)) {
669 dev_err(dev,
670 "invalid device data - cannot have both AT24_FLAG_SERIAL & AT24_FLAG_MAC.");
671 return -EINVAL;
672 }
673
674 regmap_config.val_bits = 8;
675 regmap_config.reg_bits = (flags & AT24_FLAG_ADDR16) ? 16 : 8;
676 regmap_config.disable_locking = true;
677
678 regmap = devm_regmap_init_i2c(client, ®map_config);
679 if (IS_ERR(regmap))
680 return PTR_ERR(regmap);
681
682 at24 = devm_kzalloc(dev, struct_size(at24, client, num_addresses),
683 GFP_KERNEL);
684 if (!at24)
685 return -ENOMEM;
686
687 mutex_init(&at24->lock);
688 at24->byte_len = byte_len;
689 at24->page_size = page_size;
690 at24->flags = flags;
691 at24->read_post = cdata->read_post;
692 at24->num_addresses = num_addresses;
693 at24->offset_adj = at24_get_offset_adj(flags, byte_len);
694 at24->client[0].client = client;
695 at24->client[0].regmap = regmap;
696
697 at24->vcc_reg = devm_regulator_get(dev, "vcc");
698 if (IS_ERR(at24->vcc_reg))
699 return PTR_ERR(at24->vcc_reg);
700
701 writable = !(flags & AT24_FLAG_READONLY);
702 if (writable) {
703 at24->write_max = min_t(unsigned int,
704 page_size, at24_io_limit);
705 if (!i2c_fn_i2c && at24->write_max > I2C_SMBUS_BLOCK_MAX)
706 at24->write_max = I2C_SMBUS_BLOCK_MAX;
707 }
708
709 /* use dummy devices for multiple-address chips */
710 for (i = 1; i < num_addresses; i++) {
711 err = at24_make_dummy_client(at24, i, ®map_config);
712 if (err)
713 return err;
714 }
715
716 /*
717 * We initialize nvmem_config.id to NVMEM_DEVID_AUTO even if the
718 * label property is set as some platform can have multiple eeproms
719 * with same label and we can not register each of those with same
720 * label. Failing to register those eeproms trigger cascade failure
721 * on such platform.
722 */
723 nvmem_config.id = NVMEM_DEVID_AUTO;
724
725 if (device_property_present(dev, "label")) {
726 err = device_property_read_string(dev, "label",
727 &nvmem_config.name);
728 if (err)
729 return err;
730 } else {
731 nvmem_config.name = dev_name(dev);
732 }
733
734 nvmem_config.type = NVMEM_TYPE_EEPROM;
735 nvmem_config.dev = dev;
736 nvmem_config.read_only = !writable;
737 nvmem_config.root_only = !(flags & AT24_FLAG_IRUGO);
738 nvmem_config.owner = THIS_MODULE;
739 nvmem_config.compat = true;
740 nvmem_config.base_dev = dev;
741 nvmem_config.reg_read = at24_read;
742 nvmem_config.reg_write = at24_write;
743 nvmem_config.priv = at24;
744 nvmem_config.stride = 1;
745 nvmem_config.word_size = 1;
746 nvmem_config.size = byte_len;
747
748 i2c_set_clientdata(client, at24);
749
750 err = regulator_enable(at24->vcc_reg);
751 if (err) {
752 dev_err(dev, "Failed to enable vcc regulator\n");
753 return err;
754 }
755
756 /* enable runtime pm */
757 pm_runtime_set_active(dev);
758 pm_runtime_enable(dev);
759
760 at24->nvmem = devm_nvmem_register(dev, &nvmem_config);
761 if (IS_ERR(at24->nvmem)) {
762 pm_runtime_disable(dev);
763 if (!pm_runtime_status_suspended(dev))
764 regulator_disable(at24->vcc_reg);
765 return PTR_ERR(at24->nvmem);
766 }
767
768 /*
769 * Perform a one-byte test read to verify that the
770 * chip is functional.
771 */
772 err = at24_read(at24, 0, &test_byte, 1);
773 if (err) {
774 pm_runtime_disable(dev);
775 if (!pm_runtime_status_suspended(dev))
776 regulator_disable(at24->vcc_reg);
777 return -ENODEV;
778 }
779
780 pm_runtime_idle(dev);
781
782 if (writable)
783 dev_info(dev, "%u byte %s EEPROM, writable, %u bytes/write\n",
784 byte_len, client->name, at24->write_max);
785 else
786 dev_info(dev, "%u byte %s EEPROM, read-only\n",
787 byte_len, client->name);
788
789 return 0;
790 }
791
at24_remove(struct i2c_client * client)792 static int at24_remove(struct i2c_client *client)
793 {
794 struct at24_data *at24 = i2c_get_clientdata(client);
795
796 pm_runtime_disable(&client->dev);
797 if (!pm_runtime_status_suspended(&client->dev))
798 regulator_disable(at24->vcc_reg);
799 pm_runtime_set_suspended(&client->dev);
800
801 return 0;
802 }
803
at24_suspend(struct device * dev)804 static int __maybe_unused at24_suspend(struct device *dev)
805 {
806 struct i2c_client *client = to_i2c_client(dev);
807 struct at24_data *at24 = i2c_get_clientdata(client);
808
809 return regulator_disable(at24->vcc_reg);
810 }
811
at24_resume(struct device * dev)812 static int __maybe_unused at24_resume(struct device *dev)
813 {
814 struct i2c_client *client = to_i2c_client(dev);
815 struct at24_data *at24 = i2c_get_clientdata(client);
816
817 return regulator_enable(at24->vcc_reg);
818 }
819
820 static const struct dev_pm_ops at24_pm_ops = {
821 SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
822 pm_runtime_force_resume)
823 SET_RUNTIME_PM_OPS(at24_suspend, at24_resume, NULL)
824 };
825
826 static struct i2c_driver at24_driver = {
827 .driver = {
828 .name = "at24",
829 .pm = &at24_pm_ops,
830 .of_match_table = at24_of_match,
831 .acpi_match_table = ACPI_PTR(at24_acpi_ids),
832 },
833 .probe_new = at24_probe,
834 .remove = at24_remove,
835 .id_table = at24_ids,
836 };
837
at24_init(void)838 static int __init at24_init(void)
839 {
840 if (!at24_io_limit) {
841 pr_err("at24: at24_io_limit must not be 0!\n");
842 return -EINVAL;
843 }
844
845 at24_io_limit = rounddown_pow_of_two(at24_io_limit);
846 return i2c_add_driver(&at24_driver);
847 }
848 module_init(at24_init);
849
at24_exit(void)850 static void __exit at24_exit(void)
851 {
852 i2c_del_driver(&at24_driver);
853 }
854 module_exit(at24_exit);
855
856 MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
857 MODULE_AUTHOR("David Brownell and Wolfram Sang");
858 MODULE_LICENSE("GPL");
859