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/log2.h>
18 #include <linux/bitops.h>
19 #include <linux/jiffies.h>
20 #include <linux/property.h>
21 #include <linux/acpi.h>
22 #include <linux/i2c.h>
23 #include <linux/nvmem-provider.h>
24 #include <linux/regmap.h>
25 #include <linux/platform_data/at24.h>
26 #include <linux/pm_runtime.h>
27 #include <linux/gpio/consumer.h>
28
29 /*
30 * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
31 * Differences between different vendor product lines (like Atmel AT24C or
32 * MicroChip 24LC, etc) won't much matter for typical read/write access.
33 * There are also I2C RAM chips, likewise interchangeable. One example
34 * would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
35 *
36 * However, misconfiguration can lose data. "Set 16-bit memory address"
37 * to a part with 8-bit addressing will overwrite data. Writing with too
38 * big a page size also loses data. And it's not safe to assume that the
39 * conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
40 * uses 0x51, for just one example.
41 *
42 * Accordingly, explicit board-specific configuration data should be used
43 * in almost all cases. (One partial exception is an SMBus used to access
44 * "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
45 *
46 * So this driver uses "new style" I2C driver binding, expecting to be
47 * told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
48 * similar kernel-resident tables; or, configuration data coming from
49 * a bootloader.
50 *
51 * Other than binding model, current differences from "eeprom" driver are
52 * that this one handles write access and isn't restricted to 24c02 devices.
53 * It also handles larger devices (32 kbit and up) with two-byte addresses,
54 * which won't work on pure SMBus systems.
55 */
56
57 struct at24_client {
58 struct i2c_client *client;
59 struct regmap *regmap;
60 };
61
62 struct at24_data {
63 /*
64 * Lock protects against activities from other Linux tasks,
65 * but not from changes by other I2C masters.
66 */
67 struct mutex lock;
68
69 unsigned int write_max;
70 unsigned int num_addresses;
71 unsigned int offset_adj;
72
73 u32 byte_len;
74 u16 page_size;
75 u8 flags;
76
77 struct nvmem_device *nvmem;
78
79 struct gpio_desc *wp_gpio;
80
81 /*
82 * Some chips tie up multiple I2C addresses; dummy devices reserve
83 * them for us, and we'll use them with SMBus calls.
84 */
85 struct at24_client client[];
86 };
87
88 /*
89 * This parameter is to help this driver avoid blocking other drivers out
90 * of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
91 * clock, one 256 byte read takes about 1/43 second which is excessive;
92 * but the 1/170 second it takes at 400 kHz may be quite reasonable; and
93 * at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
94 *
95 * This value is forced to be a power of two so that writes align on pages.
96 */
97 static unsigned int at24_io_limit = 128;
98 module_param_named(io_limit, at24_io_limit, uint, 0);
99 MODULE_PARM_DESC(at24_io_limit, "Maximum bytes per I/O (default 128)");
100
101 /*
102 * Specs often allow 5 msec for a page write, sometimes 20 msec;
103 * it's important to recover from write timeouts.
104 */
105 static unsigned int at24_write_timeout = 25;
106 module_param_named(write_timeout, at24_write_timeout, uint, 0);
107 MODULE_PARM_DESC(at24_write_timeout, "Time (in ms) to try writes (default 25)");
108
109 /*
110 * Both reads and writes fail if the previous write didn't complete yet. This
111 * macro loops a few times waiting at least long enough for one entire page
112 * write to work while making sure that at least one iteration is run before
113 * checking the break condition.
114 *
115 * It takes two parameters: a variable in which the future timeout in jiffies
116 * will be stored and a temporary variable holding the time of the last
117 * iteration of processing the request. Both should be unsigned integers
118 * holding at least 32 bits.
119 */
120 #define at24_loop_until_timeout(tout, op_time) \
121 for (tout = jiffies + msecs_to_jiffies(at24_write_timeout), \
122 op_time = 0; \
123 op_time ? time_before(op_time, tout) : true; \
124 usleep_range(1000, 1500), op_time = jiffies)
125
126 struct at24_chip_data {
127 /*
128 * these fields mirror their equivalents in
129 * struct at24_platform_data
130 */
131 u32 byte_len;
132 u8 flags;
133 };
134
135 #define AT24_CHIP_DATA(_name, _len, _flags) \
136 static const struct at24_chip_data _name = { \
137 .byte_len = _len, .flags = _flags, \
138 }
139
140 /* needs 8 addresses as A0-A2 are ignored */
141 AT24_CHIP_DATA(at24_data_24c00, 128 / 8, AT24_FLAG_TAKE8ADDR);
142 /* old variants can't be handled with this generic entry! */
143 AT24_CHIP_DATA(at24_data_24c01, 1024 / 8, 0);
144 AT24_CHIP_DATA(at24_data_24cs01, 16,
145 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
146 AT24_CHIP_DATA(at24_data_24c02, 2048 / 8, 0);
147 AT24_CHIP_DATA(at24_data_24cs02, 16,
148 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
149 AT24_CHIP_DATA(at24_data_24mac402, 48 / 8,
150 AT24_FLAG_MAC | AT24_FLAG_READONLY);
151 AT24_CHIP_DATA(at24_data_24mac602, 64 / 8,
152 AT24_FLAG_MAC | AT24_FLAG_READONLY);
153 /* spd is a 24c02 in memory DIMMs */
154 AT24_CHIP_DATA(at24_data_spd, 2048 / 8,
155 AT24_FLAG_READONLY | AT24_FLAG_IRUGO);
156 AT24_CHIP_DATA(at24_data_24c04, 4096 / 8, 0);
157 AT24_CHIP_DATA(at24_data_24cs04, 16,
158 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
159 /* 24rf08 quirk is handled at i2c-core */
160 AT24_CHIP_DATA(at24_data_24c08, 8192 / 8, 0);
161 AT24_CHIP_DATA(at24_data_24cs08, 16,
162 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
163 AT24_CHIP_DATA(at24_data_24c16, 16384 / 8, 0);
164 AT24_CHIP_DATA(at24_data_24cs16, 16,
165 AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
166 AT24_CHIP_DATA(at24_data_24c32, 32768 / 8, AT24_FLAG_ADDR16);
167 AT24_CHIP_DATA(at24_data_24cs32, 16,
168 AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
169 AT24_CHIP_DATA(at24_data_24c64, 65536 / 8, AT24_FLAG_ADDR16);
170 AT24_CHIP_DATA(at24_data_24cs64, 16,
171 AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
172 AT24_CHIP_DATA(at24_data_24c128, 131072 / 8, AT24_FLAG_ADDR16);
173 AT24_CHIP_DATA(at24_data_24c256, 262144 / 8, AT24_FLAG_ADDR16);
174 AT24_CHIP_DATA(at24_data_24c512, 524288 / 8, AT24_FLAG_ADDR16);
175 AT24_CHIP_DATA(at24_data_24c1024, 1048576 / 8, AT24_FLAG_ADDR16);
176 /* identical to 24c08 ? */
177 AT24_CHIP_DATA(at24_data_INT3499, 8192 / 8, 0);
178
179 static const struct i2c_device_id at24_ids[] = {
180 { "24c00", (kernel_ulong_t)&at24_data_24c00 },
181 { "24c01", (kernel_ulong_t)&at24_data_24c01 },
182 { "24cs01", (kernel_ulong_t)&at24_data_24cs01 },
183 { "24c02", (kernel_ulong_t)&at24_data_24c02 },
184 { "24cs02", (kernel_ulong_t)&at24_data_24cs02 },
185 { "24mac402", (kernel_ulong_t)&at24_data_24mac402 },
186 { "24mac602", (kernel_ulong_t)&at24_data_24mac602 },
187 { "spd", (kernel_ulong_t)&at24_data_spd },
188 { "24c04", (kernel_ulong_t)&at24_data_24c04 },
189 { "24cs04", (kernel_ulong_t)&at24_data_24cs04 },
190 { "24c08", (kernel_ulong_t)&at24_data_24c08 },
191 { "24cs08", (kernel_ulong_t)&at24_data_24cs08 },
192 { "24c16", (kernel_ulong_t)&at24_data_24c16 },
193 { "24cs16", (kernel_ulong_t)&at24_data_24cs16 },
194 { "24c32", (kernel_ulong_t)&at24_data_24c32 },
195 { "24cs32", (kernel_ulong_t)&at24_data_24cs32 },
196 { "24c64", (kernel_ulong_t)&at24_data_24c64 },
197 { "24cs64", (kernel_ulong_t)&at24_data_24cs64 },
198 { "24c128", (kernel_ulong_t)&at24_data_24c128 },
199 { "24c256", (kernel_ulong_t)&at24_data_24c256 },
200 { "24c512", (kernel_ulong_t)&at24_data_24c512 },
201 { "24c1024", (kernel_ulong_t)&at24_data_24c1024 },
202 { "at24", 0 },
203 { /* END OF LIST */ }
204 };
205 MODULE_DEVICE_TABLE(i2c, at24_ids);
206
207 static const struct of_device_id at24_of_match[] = {
208 { .compatible = "atmel,24c00", .data = &at24_data_24c00 },
209 { .compatible = "atmel,24c01", .data = &at24_data_24c01 },
210 { .compatible = "atmel,24cs01", .data = &at24_data_24cs01 },
211 { .compatible = "atmel,24c02", .data = &at24_data_24c02 },
212 { .compatible = "atmel,24cs02", .data = &at24_data_24cs02 },
213 { .compatible = "atmel,24mac402", .data = &at24_data_24mac402 },
214 { .compatible = "atmel,24mac602", .data = &at24_data_24mac602 },
215 { .compatible = "atmel,spd", .data = &at24_data_spd },
216 { .compatible = "atmel,24c04", .data = &at24_data_24c04 },
217 { .compatible = "atmel,24cs04", .data = &at24_data_24cs04 },
218 { .compatible = "atmel,24c08", .data = &at24_data_24c08 },
219 { .compatible = "atmel,24cs08", .data = &at24_data_24cs08 },
220 { .compatible = "atmel,24c16", .data = &at24_data_24c16 },
221 { .compatible = "atmel,24cs16", .data = &at24_data_24cs16 },
222 { .compatible = "atmel,24c32", .data = &at24_data_24c32 },
223 { .compatible = "atmel,24cs32", .data = &at24_data_24cs32 },
224 { .compatible = "atmel,24c64", .data = &at24_data_24c64 },
225 { .compatible = "atmel,24cs64", .data = &at24_data_24cs64 },
226 { .compatible = "atmel,24c128", .data = &at24_data_24c128 },
227 { .compatible = "atmel,24c256", .data = &at24_data_24c256 },
228 { .compatible = "atmel,24c512", .data = &at24_data_24c512 },
229 { .compatible = "atmel,24c1024", .data = &at24_data_24c1024 },
230 { /* END OF LIST */ },
231 };
232 MODULE_DEVICE_TABLE(of, at24_of_match);
233
234 static const struct acpi_device_id at24_acpi_ids[] = {
235 { "INT3499", (kernel_ulong_t)&at24_data_INT3499 },
236 { /* END OF LIST */ }
237 };
238 MODULE_DEVICE_TABLE(acpi, at24_acpi_ids);
239
240 /*
241 * This routine supports chips which consume multiple I2C addresses. It
242 * computes the addressing information to be used for a given r/w request.
243 * Assumes that sanity checks for offset happened at sysfs-layer.
244 *
245 * Slave address and byte offset derive from the offset. Always
246 * set the byte address; on a multi-master board, another master
247 * may have changed the chip's "current" address pointer.
248 */
at24_translate_offset(struct at24_data * at24,unsigned int * offset)249 static struct at24_client *at24_translate_offset(struct at24_data *at24,
250 unsigned int *offset)
251 {
252 unsigned int i;
253
254 if (at24->flags & AT24_FLAG_ADDR16) {
255 i = *offset >> 16;
256 *offset &= 0xffff;
257 } else {
258 i = *offset >> 8;
259 *offset &= 0xff;
260 }
261
262 return &at24->client[i];
263 }
264
at24_base_client_dev(struct at24_data * at24)265 static struct device *at24_base_client_dev(struct at24_data *at24)
266 {
267 return &at24->client[0].client->dev;
268 }
269
at24_adjust_read_count(struct at24_data * at24,unsigned int offset,size_t count)270 static size_t at24_adjust_read_count(struct at24_data *at24,
271 unsigned int offset, size_t count)
272 {
273 unsigned int bits;
274 size_t remainder;
275
276 /*
277 * In case of multi-address chips that don't rollover reads to
278 * the next slave address: truncate the count to the slave boundary,
279 * so that the read never straddles slaves.
280 */
281 if (at24->flags & AT24_FLAG_NO_RDROL) {
282 bits = (at24->flags & AT24_FLAG_ADDR16) ? 16 : 8;
283 remainder = BIT(bits) - offset;
284 if (count > remainder)
285 count = remainder;
286 }
287
288 if (count > at24_io_limit)
289 count = at24_io_limit;
290
291 return count;
292 }
293
at24_regmap_read(struct at24_data * at24,char * buf,unsigned int offset,size_t count)294 static ssize_t at24_regmap_read(struct at24_data *at24, char *buf,
295 unsigned int offset, size_t count)
296 {
297 unsigned long timeout, read_time;
298 struct at24_client *at24_client;
299 struct i2c_client *client;
300 struct regmap *regmap;
301 int ret;
302
303 at24_client = at24_translate_offset(at24, &offset);
304 regmap = at24_client->regmap;
305 client = at24_client->client;
306 count = at24_adjust_read_count(at24, offset, count);
307
308 /* adjust offset for mac and serial read ops */
309 offset += at24->offset_adj;
310
311 at24_loop_until_timeout(timeout, read_time) {
312 ret = regmap_bulk_read(regmap, offset, buf, count);
313 dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
314 count, offset, ret, jiffies);
315 if (!ret)
316 return count;
317 }
318
319 return -ETIMEDOUT;
320 }
321
322 /*
323 * Note that if the hardware write-protect pin is pulled high, the whole
324 * chip is normally write protected. But there are plenty of product
325 * variants here, including OTP fuses and partial chip protect.
326 *
327 * We only use page mode writes; the alternative is sloooow. These routines
328 * write at most one page.
329 */
330
at24_adjust_write_count(struct at24_data * at24,unsigned int offset,size_t count)331 static size_t at24_adjust_write_count(struct at24_data *at24,
332 unsigned int offset, size_t count)
333 {
334 unsigned int next_page;
335
336 /* write_max is at most a page */
337 if (count > at24->write_max)
338 count = at24->write_max;
339
340 /* Never roll over backwards, to the start of this page */
341 next_page = roundup(offset + 1, at24->page_size);
342 if (offset + count > next_page)
343 count = next_page - offset;
344
345 return count;
346 }
347
at24_regmap_write(struct at24_data * at24,const char * buf,unsigned int offset,size_t count)348 static ssize_t at24_regmap_write(struct at24_data *at24, const char *buf,
349 unsigned int offset, size_t count)
350 {
351 unsigned long timeout, write_time;
352 struct at24_client *at24_client;
353 struct i2c_client *client;
354 struct regmap *regmap;
355 int ret;
356
357 at24_client = at24_translate_offset(at24, &offset);
358 regmap = at24_client->regmap;
359 client = at24_client->client;
360 count = at24_adjust_write_count(at24, offset, count);
361
362 at24_loop_until_timeout(timeout, write_time) {
363 ret = regmap_bulk_write(regmap, offset, buf, count);
364 dev_dbg(&client->dev, "write %zu@%d --> %d (%ld)\n",
365 count, offset, ret, jiffies);
366 if (!ret)
367 return count;
368 }
369
370 return -ETIMEDOUT;
371 }
372
at24_read(void * priv,unsigned int off,void * val,size_t count)373 static int at24_read(void *priv, unsigned int off, void *val, size_t count)
374 {
375 struct at24_data *at24;
376 struct device *dev;
377 char *buf = val;
378 int ret;
379
380 at24 = priv;
381 dev = at24_base_client_dev(at24);
382
383 if (unlikely(!count))
384 return count;
385
386 if (off + count > at24->byte_len)
387 return -EINVAL;
388
389 ret = pm_runtime_get_sync(dev);
390 if (ret < 0) {
391 pm_runtime_put_noidle(dev);
392 return ret;
393 }
394
395 /*
396 * Read data from chip, protecting against concurrent updates
397 * from this host, but not from other I2C masters.
398 */
399 mutex_lock(&at24->lock);
400
401 while (count) {
402 ret = at24_regmap_read(at24, buf, off, count);
403 if (ret < 0) {
404 mutex_unlock(&at24->lock);
405 pm_runtime_put(dev);
406 return ret;
407 }
408 buf += ret;
409 off += ret;
410 count -= ret;
411 }
412
413 mutex_unlock(&at24->lock);
414
415 pm_runtime_put(dev);
416
417 return 0;
418 }
419
at24_write(void * priv,unsigned int off,void * val,size_t count)420 static int at24_write(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 ret;
426
427 at24 = priv;
428 dev = at24_base_client_dev(at24);
429
430 if (unlikely(!count))
431 return -EINVAL;
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 * Write data to chip, protecting against concurrent updates
444 * from this host, but not from other I2C masters.
445 */
446 mutex_lock(&at24->lock);
447 gpiod_set_value_cansleep(at24->wp_gpio, 0);
448
449 while (count) {
450 ret = at24_regmap_write(at24, buf, off, count);
451 if (ret < 0) {
452 gpiod_set_value_cansleep(at24->wp_gpio, 1);
453 mutex_unlock(&at24->lock);
454 pm_runtime_put(dev);
455 return ret;
456 }
457 buf += ret;
458 off += ret;
459 count -= ret;
460 }
461
462 gpiod_set_value_cansleep(at24->wp_gpio, 1);
463 mutex_unlock(&at24->lock);
464
465 pm_runtime_put(dev);
466
467 return 0;
468 }
469
at24_properties_to_pdata(struct device * dev,struct at24_platform_data * chip)470 static void at24_properties_to_pdata(struct device *dev,
471 struct at24_platform_data *chip)
472 {
473 int err;
474 u32 val;
475
476 if (device_property_present(dev, "read-only"))
477 chip->flags |= AT24_FLAG_READONLY;
478 if (device_property_present(dev, "no-read-rollover"))
479 chip->flags |= AT24_FLAG_NO_RDROL;
480
481 err = device_property_read_u32(dev, "address-width", &val);
482 if (!err) {
483 switch (val) {
484 case 8:
485 if (chip->flags & AT24_FLAG_ADDR16)
486 dev_warn(dev, "Override address width to be 8, while default is 16\n");
487 chip->flags &= ~AT24_FLAG_ADDR16;
488 break;
489 case 16:
490 chip->flags |= AT24_FLAG_ADDR16;
491 break;
492 default:
493 dev_warn(dev, "Bad \"address-width\" property: %u\n",
494 val);
495 }
496 }
497
498 err = device_property_read_u32(dev, "size", &val);
499 if (!err)
500 chip->byte_len = val;
501
502 err = device_property_read_u32(dev, "pagesize", &val);
503 if (!err) {
504 chip->page_size = val;
505 } else {
506 /*
507 * This is slow, but we can't know all eeproms, so we better
508 * play safe. Specifying custom eeprom-types via platform_data
509 * is recommended anyhow.
510 */
511 chip->page_size = 1;
512 }
513 }
514
at24_get_pdata(struct device * dev,struct at24_platform_data * pdata)515 static int at24_get_pdata(struct device *dev, struct at24_platform_data *pdata)
516 {
517 struct device_node *of_node = dev->of_node;
518 const struct at24_chip_data *cdata;
519 const struct i2c_device_id *id;
520 struct at24_platform_data *pd;
521
522 pd = dev_get_platdata(dev);
523 if (pd) {
524 memcpy(pdata, pd, sizeof(*pdata));
525 return 0;
526 }
527
528 id = i2c_match_id(at24_ids, to_i2c_client(dev));
529
530 /*
531 * The I2C core allows OF nodes compatibles to match against the
532 * I2C device ID table as a fallback, so check not only if an OF
533 * node is present but also if it matches an OF device ID entry.
534 */
535 if (of_node && of_match_device(at24_of_match, dev))
536 cdata = of_device_get_match_data(dev);
537 else if (id)
538 cdata = (void *)id->driver_data;
539 else
540 cdata = acpi_device_get_match_data(dev);
541
542 if (!cdata)
543 return -ENODEV;
544
545 pdata->byte_len = cdata->byte_len;
546 pdata->flags = cdata->flags;
547 at24_properties_to_pdata(dev, pdata);
548
549 return 0;
550 }
551
at24_remove_dummy_clients(struct at24_data * at24)552 static void at24_remove_dummy_clients(struct at24_data *at24)
553 {
554 int i;
555
556 for (i = 1; i < at24->num_addresses; i++)
557 i2c_unregister_device(at24->client[i].client);
558 }
559
at24_make_dummy_client(struct at24_data * at24,unsigned int index,struct regmap_config * regmap_config)560 static int at24_make_dummy_client(struct at24_data *at24, unsigned int index,
561 struct regmap_config *regmap_config)
562 {
563 struct i2c_client *base_client, *dummy_client;
564 unsigned short int addr;
565 struct regmap *regmap;
566 struct device *dev;
567
568 base_client = at24->client[0].client;
569 dev = &base_client->dev;
570 addr = base_client->addr + index;
571
572 dummy_client = i2c_new_dummy(base_client->adapter,
573 base_client->addr + index);
574 if (!dummy_client) {
575 dev_err(dev, "address 0x%02x unavailable\n", addr);
576 return -EADDRINUSE;
577 }
578
579 regmap = devm_regmap_init_i2c(dummy_client, regmap_config);
580 if (IS_ERR(regmap)) {
581 i2c_unregister_device(dummy_client);
582 return PTR_ERR(regmap);
583 }
584
585 at24->client[index].client = dummy_client;
586 at24->client[index].regmap = regmap;
587
588 return 0;
589 }
590
at24_get_offset_adj(u8 flags,unsigned int byte_len)591 static unsigned int at24_get_offset_adj(u8 flags, unsigned int byte_len)
592 {
593 if (flags & AT24_FLAG_MAC) {
594 /* EUI-48 starts from 0x9a, EUI-64 from 0x98 */
595 return 0xa0 - byte_len;
596 } else if (flags & AT24_FLAG_SERIAL && flags & AT24_FLAG_ADDR16) {
597 /*
598 * For 16 bit address pointers, the word address must contain
599 * a '10' sequence in bits 11 and 10 regardless of the
600 * intended position of the address pointer.
601 */
602 return 0x0800;
603 } else if (flags & AT24_FLAG_SERIAL) {
604 /*
605 * Otherwise the word address must begin with a '10' sequence,
606 * regardless of the intended address.
607 */
608 return 0x0080;
609 } else {
610 return 0;
611 }
612 }
613
at24_probe(struct i2c_client * client)614 static int at24_probe(struct i2c_client *client)
615 {
616 struct regmap_config regmap_config = { };
617 struct nvmem_config nvmem_config = { };
618 struct at24_platform_data pdata = { };
619 struct device *dev = &client->dev;
620 bool i2c_fn_i2c, i2c_fn_block;
621 unsigned int i, num_addresses;
622 struct at24_data *at24;
623 struct regmap *regmap;
624 size_t at24_size;
625 bool writable;
626 u8 test_byte;
627 int err;
628
629 i2c_fn_i2c = i2c_check_functionality(client->adapter, I2C_FUNC_I2C);
630 i2c_fn_block = i2c_check_functionality(client->adapter,
631 I2C_FUNC_SMBUS_WRITE_I2C_BLOCK);
632
633 err = at24_get_pdata(dev, &pdata);
634 if (err)
635 return err;
636
637 if (!i2c_fn_i2c && !i2c_fn_block)
638 pdata.page_size = 1;
639
640 if (!pdata.page_size) {
641 dev_err(dev, "page_size must not be 0!\n");
642 return -EINVAL;
643 }
644
645 if (!is_power_of_2(pdata.page_size))
646 dev_warn(dev, "page_size looks suspicious (no power of 2)!\n");
647
648 if (pdata.flags & AT24_FLAG_TAKE8ADDR)
649 num_addresses = 8;
650 else
651 num_addresses = DIV_ROUND_UP(pdata.byte_len,
652 (pdata.flags & AT24_FLAG_ADDR16) ? 65536 : 256);
653
654 if ((pdata.flags & AT24_FLAG_SERIAL) && (pdata.flags & AT24_FLAG_MAC)) {
655 dev_err(dev,
656 "invalid device data - cannot have both AT24_FLAG_SERIAL & AT24_FLAG_MAC.");
657 return -EINVAL;
658 }
659
660 regmap_config.val_bits = 8;
661 regmap_config.reg_bits = (pdata.flags & AT24_FLAG_ADDR16) ? 16 : 8;
662 regmap_config.disable_locking = true;
663
664 regmap = devm_regmap_init_i2c(client, ®map_config);
665 if (IS_ERR(regmap))
666 return PTR_ERR(regmap);
667
668 at24_size = sizeof(*at24) + num_addresses * sizeof(struct at24_client);
669 at24 = devm_kzalloc(dev, at24_size, GFP_KERNEL);
670 if (!at24)
671 return -ENOMEM;
672
673 mutex_init(&at24->lock);
674 at24->byte_len = pdata.byte_len;
675 at24->page_size = pdata.page_size;
676 at24->flags = pdata.flags;
677 at24->num_addresses = num_addresses;
678 at24->offset_adj = at24_get_offset_adj(pdata.flags, pdata.byte_len);
679 at24->client[0].client = client;
680 at24->client[0].regmap = regmap;
681
682 at24->wp_gpio = devm_gpiod_get_optional(dev, "wp", GPIOD_OUT_HIGH);
683 if (IS_ERR(at24->wp_gpio))
684 return PTR_ERR(at24->wp_gpio);
685
686 writable = !(pdata.flags & AT24_FLAG_READONLY);
687 if (writable) {
688 at24->write_max = min_t(unsigned int,
689 pdata.page_size, at24_io_limit);
690 if (!i2c_fn_i2c && at24->write_max > I2C_SMBUS_BLOCK_MAX)
691 at24->write_max = I2C_SMBUS_BLOCK_MAX;
692 }
693
694 /* use dummy devices for multiple-address chips */
695 for (i = 1; i < num_addresses; i++) {
696 err = at24_make_dummy_client(at24, i, ®map_config);
697 if (err) {
698 at24_remove_dummy_clients(at24);
699 return err;
700 }
701 }
702
703 i2c_set_clientdata(client, at24);
704
705 /* enable runtime pm */
706 pm_runtime_set_active(dev);
707 pm_runtime_enable(dev);
708
709 /*
710 * Perform a one-byte test read to verify that the
711 * chip is functional.
712 */
713 err = at24_read(at24, 0, &test_byte, 1);
714 pm_runtime_idle(dev);
715 if (err) {
716 err = -ENODEV;
717 goto err_clients;
718 }
719
720 nvmem_config.name = dev_name(dev);
721 nvmem_config.dev = dev;
722 nvmem_config.read_only = !writable;
723 nvmem_config.root_only = true;
724 nvmem_config.owner = THIS_MODULE;
725 nvmem_config.compat = true;
726 nvmem_config.base_dev = dev;
727 nvmem_config.reg_read = at24_read;
728 nvmem_config.reg_write = at24_write;
729 nvmem_config.priv = at24;
730 nvmem_config.stride = 1;
731 nvmem_config.word_size = 1;
732 nvmem_config.size = pdata.byte_len;
733
734 at24->nvmem = devm_nvmem_register(dev, &nvmem_config);
735 if (IS_ERR(at24->nvmem)) {
736 err = PTR_ERR(at24->nvmem);
737 goto err_clients;
738 }
739
740 dev_info(dev, "%u byte %s EEPROM, %s, %u bytes/write\n",
741 pdata.byte_len, client->name,
742 writable ? "writable" : "read-only", at24->write_max);
743
744 /* export data to kernel code */
745 if (pdata.setup)
746 pdata.setup(at24->nvmem, pdata.context);
747
748 return 0;
749
750 err_clients:
751 at24_remove_dummy_clients(at24);
752 pm_runtime_disable(dev);
753
754 return err;
755 }
756
at24_remove(struct i2c_client * client)757 static int at24_remove(struct i2c_client *client)
758 {
759 struct at24_data *at24;
760
761 at24 = i2c_get_clientdata(client);
762
763 at24_remove_dummy_clients(at24);
764 pm_runtime_disable(&client->dev);
765 pm_runtime_set_suspended(&client->dev);
766
767 return 0;
768 }
769
770 static struct i2c_driver at24_driver = {
771 .driver = {
772 .name = "at24",
773 .of_match_table = at24_of_match,
774 .acpi_match_table = ACPI_PTR(at24_acpi_ids),
775 },
776 .probe_new = at24_probe,
777 .remove = at24_remove,
778 .id_table = at24_ids,
779 };
780
at24_init(void)781 static int __init at24_init(void)
782 {
783 if (!at24_io_limit) {
784 pr_err("at24: at24_io_limit must not be 0!\n");
785 return -EINVAL;
786 }
787
788 at24_io_limit = rounddown_pow_of_two(at24_io_limit);
789 return i2c_add_driver(&at24_driver);
790 }
791 module_init(at24_init);
792
at24_exit(void)793 static void __exit at24_exit(void)
794 {
795 i2c_del_driver(&at24_driver);
796 }
797 module_exit(at24_exit);
798
799 MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
800 MODULE_AUTHOR("David Brownell and Wolfram Sang");
801 MODULE_LICENSE("GPL");
802
