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, &regmap_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, &regmap_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");