xref: /openbmc/linux/drivers/rtc/rtc-ds1307.c (revision 4f3db074)
1 /*
2  * rtc-ds1307.c - RTC driver for some mostly-compatible I2C chips.
3  *
4  *  Copyright (C) 2005 James Chapman (ds1337 core)
5  *  Copyright (C) 2006 David Brownell
6  *  Copyright (C) 2009 Matthias Fuchs (rx8025 support)
7  *  Copyright (C) 2012 Bertrand Achard (nvram access fixes)
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License version 2 as
11  * published by the Free Software Foundation.
12  */
13 
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/slab.h>
17 #include <linux/i2c.h>
18 #include <linux/string.h>
19 #include <linux/rtc.h>
20 #include <linux/bcd.h>
21 #include <linux/rtc/ds1307.h>
22 
23 /*
24  * We can't determine type by probing, but if we expect pre-Linux code
25  * to have set the chip up as a clock (turning on the oscillator and
26  * setting the date and time), Linux can ignore the non-clock features.
27  * That's a natural job for a factory or repair bench.
28  */
29 enum ds_type {
30 	ds_1307,
31 	ds_1337,
32 	ds_1338,
33 	ds_1339,
34 	ds_1340,
35 	ds_1388,
36 	ds_3231,
37 	m41t00,
38 	mcp794xx,
39 	rx_8025,
40 	last_ds_type /* always last */
41 	/* rs5c372 too?  different address... */
42 };
43 
44 
45 /* RTC registers don't differ much, except for the century flag */
46 #define DS1307_REG_SECS		0x00	/* 00-59 */
47 #	define DS1307_BIT_CH		0x80
48 #	define DS1340_BIT_nEOSC		0x80
49 #	define MCP794XX_BIT_ST		0x80
50 #define DS1307_REG_MIN		0x01	/* 00-59 */
51 #define DS1307_REG_HOUR		0x02	/* 00-23, or 1-12{am,pm} */
52 #	define DS1307_BIT_12HR		0x40	/* in REG_HOUR */
53 #	define DS1307_BIT_PM		0x20	/* in REG_HOUR */
54 #	define DS1340_BIT_CENTURY_EN	0x80	/* in REG_HOUR */
55 #	define DS1340_BIT_CENTURY	0x40	/* in REG_HOUR */
56 #define DS1307_REG_WDAY		0x03	/* 01-07 */
57 #	define MCP794XX_BIT_VBATEN	0x08
58 #define DS1307_REG_MDAY		0x04	/* 01-31 */
59 #define DS1307_REG_MONTH	0x05	/* 01-12 */
60 #	define DS1337_BIT_CENTURY	0x80	/* in REG_MONTH */
61 #define DS1307_REG_YEAR		0x06	/* 00-99 */
62 
63 /*
64  * Other registers (control, status, alarms, trickle charge, NVRAM, etc)
65  * start at 7, and they differ a LOT. Only control and status matter for
66  * basic RTC date and time functionality; be careful using them.
67  */
68 #define DS1307_REG_CONTROL	0x07		/* or ds1338 */
69 #	define DS1307_BIT_OUT		0x80
70 #	define DS1338_BIT_OSF		0x20
71 #	define DS1307_BIT_SQWE		0x10
72 #	define DS1307_BIT_RS1		0x02
73 #	define DS1307_BIT_RS0		0x01
74 #define DS1337_REG_CONTROL	0x0e
75 #	define DS1337_BIT_nEOSC		0x80
76 #	define DS1339_BIT_BBSQI		0x20
77 #	define DS3231_BIT_BBSQW		0x40 /* same as BBSQI */
78 #	define DS1337_BIT_RS2		0x10
79 #	define DS1337_BIT_RS1		0x08
80 #	define DS1337_BIT_INTCN		0x04
81 #	define DS1337_BIT_A2IE		0x02
82 #	define DS1337_BIT_A1IE		0x01
83 #define DS1340_REG_CONTROL	0x07
84 #	define DS1340_BIT_OUT		0x80
85 #	define DS1340_BIT_FT		0x40
86 #	define DS1340_BIT_CALIB_SIGN	0x20
87 #	define DS1340_M_CALIBRATION	0x1f
88 #define DS1340_REG_FLAG		0x09
89 #	define DS1340_BIT_OSF		0x80
90 #define DS1337_REG_STATUS	0x0f
91 #	define DS1337_BIT_OSF		0x80
92 #	define DS1337_BIT_A2I		0x02
93 #	define DS1337_BIT_A1I		0x01
94 #define DS1339_REG_ALARM1_SECS	0x07
95 
96 #define DS13XX_TRICKLE_CHARGER_MAGIC	0xa0
97 
98 #define RX8025_REG_CTRL1	0x0e
99 #	define RX8025_BIT_2412		0x20
100 #define RX8025_REG_CTRL2	0x0f
101 #	define RX8025_BIT_PON		0x10
102 #	define RX8025_BIT_VDET		0x40
103 #	define RX8025_BIT_XST		0x20
104 
105 
106 struct ds1307 {
107 	u8			offset; /* register's offset */
108 	u8			regs[11];
109 	u16			nvram_offset;
110 	struct bin_attribute	*nvram;
111 	enum ds_type		type;
112 	unsigned long		flags;
113 #define HAS_NVRAM	0		/* bit 0 == sysfs file active */
114 #define HAS_ALARM	1		/* bit 1 == irq claimed */
115 	struct i2c_client	*client;
116 	struct rtc_device	*rtc;
117 	struct work_struct	work;
118 	s32 (*read_block_data)(const struct i2c_client *client, u8 command,
119 			       u8 length, u8 *values);
120 	s32 (*write_block_data)(const struct i2c_client *client, u8 command,
121 				u8 length, const u8 *values);
122 };
123 
124 struct chip_desc {
125 	unsigned		alarm:1;
126 	u16			nvram_offset;
127 	u16			nvram_size;
128 	u16			trickle_charger_reg;
129 	u8			trickle_charger_setup;
130 	u8			(*do_trickle_setup)(struct i2c_client *, uint32_t, bool);
131 };
132 
133 static u8 do_trickle_setup_ds1339(struct i2c_client *,
134 				  uint32_t ohms, bool diode);
135 
136 static struct chip_desc chips[last_ds_type] = {
137 	[ds_1307] = {
138 		.nvram_offset	= 8,
139 		.nvram_size	= 56,
140 	},
141 	[ds_1337] = {
142 		.alarm		= 1,
143 	},
144 	[ds_1338] = {
145 		.nvram_offset	= 8,
146 		.nvram_size	= 56,
147 	},
148 	[ds_1339] = {
149 		.alarm		= 1,
150 		.trickle_charger_reg = 0x10,
151 		.do_trickle_setup = &do_trickle_setup_ds1339,
152 	},
153 	[ds_1340] = {
154 		.trickle_charger_reg = 0x08,
155 	},
156 	[ds_1388] = {
157 		.trickle_charger_reg = 0x0a,
158 	},
159 	[ds_3231] = {
160 		.alarm		= 1,
161 	},
162 	[mcp794xx] = {
163 		.alarm		= 1,
164 		/* this is battery backed SRAM */
165 		.nvram_offset	= 0x20,
166 		.nvram_size	= 0x40,
167 	},
168 };
169 
170 static const struct i2c_device_id ds1307_id[] = {
171 	{ "ds1307", ds_1307 },
172 	{ "ds1337", ds_1337 },
173 	{ "ds1338", ds_1338 },
174 	{ "ds1339", ds_1339 },
175 	{ "ds1388", ds_1388 },
176 	{ "ds1340", ds_1340 },
177 	{ "ds3231", ds_3231 },
178 	{ "m41t00", m41t00 },
179 	{ "mcp7940x", mcp794xx },
180 	{ "mcp7941x", mcp794xx },
181 	{ "pt7c4338", ds_1307 },
182 	{ "rx8025", rx_8025 },
183 	{ }
184 };
185 MODULE_DEVICE_TABLE(i2c, ds1307_id);
186 
187 /*----------------------------------------------------------------------*/
188 
189 #define BLOCK_DATA_MAX_TRIES 10
190 
191 static s32 ds1307_read_block_data_once(const struct i2c_client *client,
192 				       u8 command, u8 length, u8 *values)
193 {
194 	s32 i, data;
195 
196 	for (i = 0; i < length; i++) {
197 		data = i2c_smbus_read_byte_data(client, command + i);
198 		if (data < 0)
199 			return data;
200 		values[i] = data;
201 	}
202 	return i;
203 }
204 
205 static s32 ds1307_read_block_data(const struct i2c_client *client, u8 command,
206 				  u8 length, u8 *values)
207 {
208 	u8 oldvalues[255];
209 	s32 ret;
210 	int tries = 0;
211 
212 	dev_dbg(&client->dev, "ds1307_read_block_data (length=%d)\n", length);
213 	ret = ds1307_read_block_data_once(client, command, length, values);
214 	if (ret < 0)
215 		return ret;
216 	do {
217 		if (++tries > BLOCK_DATA_MAX_TRIES) {
218 			dev_err(&client->dev,
219 				"ds1307_read_block_data failed\n");
220 			return -EIO;
221 		}
222 		memcpy(oldvalues, values, length);
223 		ret = ds1307_read_block_data_once(client, command, length,
224 						  values);
225 		if (ret < 0)
226 			return ret;
227 	} while (memcmp(oldvalues, values, length));
228 	return length;
229 }
230 
231 static s32 ds1307_write_block_data(const struct i2c_client *client, u8 command,
232 				   u8 length, const u8 *values)
233 {
234 	u8 currvalues[255];
235 	int tries = 0;
236 
237 	dev_dbg(&client->dev, "ds1307_write_block_data (length=%d)\n", length);
238 	do {
239 		s32 i, ret;
240 
241 		if (++tries > BLOCK_DATA_MAX_TRIES) {
242 			dev_err(&client->dev,
243 				"ds1307_write_block_data failed\n");
244 			return -EIO;
245 		}
246 		for (i = 0; i < length; i++) {
247 			ret = i2c_smbus_write_byte_data(client, command + i,
248 							values[i]);
249 			if (ret < 0)
250 				return ret;
251 		}
252 		ret = ds1307_read_block_data_once(client, command, length,
253 						  currvalues);
254 		if (ret < 0)
255 			return ret;
256 	} while (memcmp(currvalues, values, length));
257 	return length;
258 }
259 
260 /*----------------------------------------------------------------------*/
261 
262 /* These RTC devices are not designed to be connected to a SMbus adapter.
263    SMbus limits block operations length to 32 bytes, whereas it's not
264    limited on I2C buses. As a result, accesses may exceed 32 bytes;
265    in that case, split them into smaller blocks */
266 
267 static s32 ds1307_native_smbus_write_block_data(const struct i2c_client *client,
268 				u8 command, u8 length, const u8 *values)
269 {
270 	u8 suboffset = 0;
271 
272 	if (length <= I2C_SMBUS_BLOCK_MAX)
273 		return i2c_smbus_write_i2c_block_data(client,
274 					command, length, values);
275 
276 	while (suboffset < length) {
277 		s32 retval = i2c_smbus_write_i2c_block_data(client,
278 				command + suboffset,
279 				min(I2C_SMBUS_BLOCK_MAX, length - suboffset),
280 				values + suboffset);
281 		if (retval < 0)
282 			return retval;
283 
284 		suboffset += I2C_SMBUS_BLOCK_MAX;
285 	}
286 	return length;
287 }
288 
289 static s32 ds1307_native_smbus_read_block_data(const struct i2c_client *client,
290 				u8 command, u8 length, u8 *values)
291 {
292 	u8 suboffset = 0;
293 
294 	if (length <= I2C_SMBUS_BLOCK_MAX)
295 		return i2c_smbus_read_i2c_block_data(client,
296 					command, length, values);
297 
298 	while (suboffset < length) {
299 		s32 retval = i2c_smbus_read_i2c_block_data(client,
300 				command + suboffset,
301 				min(I2C_SMBUS_BLOCK_MAX, length - suboffset),
302 				values + suboffset);
303 		if (retval < 0)
304 			return retval;
305 
306 		suboffset += I2C_SMBUS_BLOCK_MAX;
307 	}
308 	return length;
309 }
310 
311 /*----------------------------------------------------------------------*/
312 
313 /*
314  * The IRQ logic includes a "real" handler running in IRQ context just
315  * long enough to schedule this workqueue entry.   We need a task context
316  * to talk to the RTC, since I2C I/O calls require that; and disable the
317  * IRQ until we clear its status on the chip, so that this handler can
318  * work with any type of triggering (not just falling edge).
319  *
320  * The ds1337 and ds1339 both have two alarms, but we only use the first
321  * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
322  * signal; ds1339 chips have only one alarm signal.
323  */
324 static void ds1307_work(struct work_struct *work)
325 {
326 	struct ds1307		*ds1307;
327 	struct i2c_client	*client;
328 	struct mutex		*lock;
329 	int			stat, control;
330 
331 	ds1307 = container_of(work, struct ds1307, work);
332 	client = ds1307->client;
333 	lock = &ds1307->rtc->ops_lock;
334 
335 	mutex_lock(lock);
336 	stat = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
337 	if (stat < 0)
338 		goto out;
339 
340 	if (stat & DS1337_BIT_A1I) {
341 		stat &= ~DS1337_BIT_A1I;
342 		i2c_smbus_write_byte_data(client, DS1337_REG_STATUS, stat);
343 
344 		control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
345 		if (control < 0)
346 			goto out;
347 
348 		control &= ~DS1337_BIT_A1IE;
349 		i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, control);
350 
351 		rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
352 	}
353 
354 out:
355 	if (test_bit(HAS_ALARM, &ds1307->flags))
356 		enable_irq(client->irq);
357 	mutex_unlock(lock);
358 }
359 
360 static irqreturn_t ds1307_irq(int irq, void *dev_id)
361 {
362 	struct i2c_client	*client = dev_id;
363 	struct ds1307		*ds1307 = i2c_get_clientdata(client);
364 
365 	disable_irq_nosync(irq);
366 	schedule_work(&ds1307->work);
367 	return IRQ_HANDLED;
368 }
369 
370 /*----------------------------------------------------------------------*/
371 
372 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
373 {
374 	struct ds1307	*ds1307 = dev_get_drvdata(dev);
375 	int		tmp;
376 
377 	/* read the RTC date and time registers all at once */
378 	tmp = ds1307->read_block_data(ds1307->client,
379 		ds1307->offset, 7, ds1307->regs);
380 	if (tmp != 7) {
381 		dev_err(dev, "%s error %d\n", "read", tmp);
382 		return -EIO;
383 	}
384 
385 	dev_dbg(dev, "%s: %7ph\n", "read", ds1307->regs);
386 
387 	t->tm_sec = bcd2bin(ds1307->regs[DS1307_REG_SECS] & 0x7f);
388 	t->tm_min = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f);
389 	tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
390 	t->tm_hour = bcd2bin(tmp);
391 	t->tm_wday = bcd2bin(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
392 	t->tm_mday = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
393 	tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
394 	t->tm_mon = bcd2bin(tmp) - 1;
395 
396 	/* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
397 	t->tm_year = bcd2bin(ds1307->regs[DS1307_REG_YEAR]) + 100;
398 
399 	dev_dbg(dev, "%s secs=%d, mins=%d, "
400 		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
401 		"read", t->tm_sec, t->tm_min,
402 		t->tm_hour, t->tm_mday,
403 		t->tm_mon, t->tm_year, t->tm_wday);
404 
405 	/* initial clock setting can be undefined */
406 	return rtc_valid_tm(t);
407 }
408 
409 static int ds1307_set_time(struct device *dev, struct rtc_time *t)
410 {
411 	struct ds1307	*ds1307 = dev_get_drvdata(dev);
412 	int		result;
413 	int		tmp;
414 	u8		*buf = ds1307->regs;
415 
416 	dev_dbg(dev, "%s secs=%d, mins=%d, "
417 		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
418 		"write", t->tm_sec, t->tm_min,
419 		t->tm_hour, t->tm_mday,
420 		t->tm_mon, t->tm_year, t->tm_wday);
421 
422 	buf[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
423 	buf[DS1307_REG_MIN] = bin2bcd(t->tm_min);
424 	buf[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
425 	buf[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
426 	buf[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
427 	buf[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
428 
429 	/* assume 20YY not 19YY */
430 	tmp = t->tm_year - 100;
431 	buf[DS1307_REG_YEAR] = bin2bcd(tmp);
432 
433 	switch (ds1307->type) {
434 	case ds_1337:
435 	case ds_1339:
436 	case ds_3231:
437 		buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
438 		break;
439 	case ds_1340:
440 		buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
441 				| DS1340_BIT_CENTURY;
442 		break;
443 	case mcp794xx:
444 		/*
445 		 * these bits were cleared when preparing the date/time
446 		 * values and need to be set again before writing the
447 		 * buffer out to the device.
448 		 */
449 		buf[DS1307_REG_SECS] |= MCP794XX_BIT_ST;
450 		buf[DS1307_REG_WDAY] |= MCP794XX_BIT_VBATEN;
451 		break;
452 	default:
453 		break;
454 	}
455 
456 	dev_dbg(dev, "%s: %7ph\n", "write", buf);
457 
458 	result = ds1307->write_block_data(ds1307->client,
459 		ds1307->offset, 7, buf);
460 	if (result < 0) {
461 		dev_err(dev, "%s error %d\n", "write", result);
462 		return result;
463 	}
464 	return 0;
465 }
466 
467 static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
468 {
469 	struct i2c_client       *client = to_i2c_client(dev);
470 	struct ds1307		*ds1307 = i2c_get_clientdata(client);
471 	int			ret;
472 
473 	if (!test_bit(HAS_ALARM, &ds1307->flags))
474 		return -EINVAL;
475 
476 	/* read all ALARM1, ALARM2, and status registers at once */
477 	ret = ds1307->read_block_data(client,
478 			DS1339_REG_ALARM1_SECS, 9, ds1307->regs);
479 	if (ret != 9) {
480 		dev_err(dev, "%s error %d\n", "alarm read", ret);
481 		return -EIO;
482 	}
483 
484 	dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
485 			"alarm read",
486 			ds1307->regs[0], ds1307->regs[1],
487 			ds1307->regs[2], ds1307->regs[3],
488 			ds1307->regs[4], ds1307->regs[5],
489 			ds1307->regs[6], ds1307->regs[7],
490 			ds1307->regs[8]);
491 
492 	/*
493 	 * report alarm time (ALARM1); assume 24 hour and day-of-month modes,
494 	 * and that all four fields are checked matches
495 	 */
496 	t->time.tm_sec = bcd2bin(ds1307->regs[0] & 0x7f);
497 	t->time.tm_min = bcd2bin(ds1307->regs[1] & 0x7f);
498 	t->time.tm_hour = bcd2bin(ds1307->regs[2] & 0x3f);
499 	t->time.tm_mday = bcd2bin(ds1307->regs[3] & 0x3f);
500 	t->time.tm_mon = -1;
501 	t->time.tm_year = -1;
502 	t->time.tm_wday = -1;
503 	t->time.tm_yday = -1;
504 	t->time.tm_isdst = -1;
505 
506 	/* ... and status */
507 	t->enabled = !!(ds1307->regs[7] & DS1337_BIT_A1IE);
508 	t->pending = !!(ds1307->regs[8] & DS1337_BIT_A1I);
509 
510 	dev_dbg(dev, "%s secs=%d, mins=%d, "
511 		"hours=%d, mday=%d, enabled=%d, pending=%d\n",
512 		"alarm read", t->time.tm_sec, t->time.tm_min,
513 		t->time.tm_hour, t->time.tm_mday,
514 		t->enabled, t->pending);
515 
516 	return 0;
517 }
518 
519 static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
520 {
521 	struct i2c_client	*client = to_i2c_client(dev);
522 	struct ds1307		*ds1307 = i2c_get_clientdata(client);
523 	unsigned char		*buf = ds1307->regs;
524 	u8			control, status;
525 	int			ret;
526 
527 	if (!test_bit(HAS_ALARM, &ds1307->flags))
528 		return -EINVAL;
529 
530 	dev_dbg(dev, "%s secs=%d, mins=%d, "
531 		"hours=%d, mday=%d, enabled=%d, pending=%d\n",
532 		"alarm set", t->time.tm_sec, t->time.tm_min,
533 		t->time.tm_hour, t->time.tm_mday,
534 		t->enabled, t->pending);
535 
536 	/* read current status of both alarms and the chip */
537 	ret = ds1307->read_block_data(client,
538 			DS1339_REG_ALARM1_SECS, 9, buf);
539 	if (ret != 9) {
540 		dev_err(dev, "%s error %d\n", "alarm write", ret);
541 		return -EIO;
542 	}
543 	control = ds1307->regs[7];
544 	status = ds1307->regs[8];
545 
546 	dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
547 			"alarm set (old status)",
548 			ds1307->regs[0], ds1307->regs[1],
549 			ds1307->regs[2], ds1307->regs[3],
550 			ds1307->regs[4], ds1307->regs[5],
551 			ds1307->regs[6], control, status);
552 
553 	/* set ALARM1, using 24 hour and day-of-month modes */
554 	buf[0] = bin2bcd(t->time.tm_sec);
555 	buf[1] = bin2bcd(t->time.tm_min);
556 	buf[2] = bin2bcd(t->time.tm_hour);
557 	buf[3] = bin2bcd(t->time.tm_mday);
558 
559 	/* set ALARM2 to non-garbage */
560 	buf[4] = 0;
561 	buf[5] = 0;
562 	buf[6] = 0;
563 
564 	/* optionally enable ALARM1 */
565 	buf[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
566 	if (t->enabled) {
567 		dev_dbg(dev, "alarm IRQ armed\n");
568 		buf[7] |= DS1337_BIT_A1IE;	/* only ALARM1 is used */
569 	}
570 	buf[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
571 
572 	ret = ds1307->write_block_data(client,
573 			DS1339_REG_ALARM1_SECS, 9, buf);
574 	if (ret < 0) {
575 		dev_err(dev, "can't set alarm time\n");
576 		return ret;
577 	}
578 
579 	return 0;
580 }
581 
582 static int ds1307_alarm_irq_enable(struct device *dev, unsigned int enabled)
583 {
584 	struct i2c_client	*client = to_i2c_client(dev);
585 	struct ds1307		*ds1307 = i2c_get_clientdata(client);
586 	int			ret;
587 
588 	if (!test_bit(HAS_ALARM, &ds1307->flags))
589 		return -ENOTTY;
590 
591 	ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
592 	if (ret < 0)
593 		return ret;
594 
595 	if (enabled)
596 		ret |= DS1337_BIT_A1IE;
597 	else
598 		ret &= ~DS1337_BIT_A1IE;
599 
600 	ret = i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, ret);
601 	if (ret < 0)
602 		return ret;
603 
604 	return 0;
605 }
606 
607 static const struct rtc_class_ops ds13xx_rtc_ops = {
608 	.read_time	= ds1307_get_time,
609 	.set_time	= ds1307_set_time,
610 	.read_alarm	= ds1337_read_alarm,
611 	.set_alarm	= ds1337_set_alarm,
612 	.alarm_irq_enable = ds1307_alarm_irq_enable,
613 };
614 
615 /*----------------------------------------------------------------------*/
616 
617 /*
618  * Alarm support for mcp794xx devices.
619  */
620 
621 #define MCP794XX_REG_CONTROL		0x07
622 #	define MCP794XX_BIT_ALM0_EN	0x10
623 #	define MCP794XX_BIT_ALM1_EN	0x20
624 #define MCP794XX_REG_ALARM0_BASE	0x0a
625 #define MCP794XX_REG_ALARM0_CTRL	0x0d
626 #define MCP794XX_REG_ALARM1_BASE	0x11
627 #define MCP794XX_REG_ALARM1_CTRL	0x14
628 #	define MCP794XX_BIT_ALMX_IF	(1 << 3)
629 #	define MCP794XX_BIT_ALMX_C0	(1 << 4)
630 #	define MCP794XX_BIT_ALMX_C1	(1 << 5)
631 #	define MCP794XX_BIT_ALMX_C2	(1 << 6)
632 #	define MCP794XX_BIT_ALMX_POL	(1 << 7)
633 #	define MCP794XX_MSK_ALMX_MATCH	(MCP794XX_BIT_ALMX_C0 | \
634 					 MCP794XX_BIT_ALMX_C1 | \
635 					 MCP794XX_BIT_ALMX_C2)
636 
637 static void mcp794xx_work(struct work_struct *work)
638 {
639 	struct ds1307 *ds1307 = container_of(work, struct ds1307, work);
640 	struct i2c_client *client = ds1307->client;
641 	int reg, ret;
642 
643 	mutex_lock(&ds1307->rtc->ops_lock);
644 
645 	/* Check and clear alarm 0 interrupt flag. */
646 	reg = i2c_smbus_read_byte_data(client, MCP794XX_REG_ALARM0_CTRL);
647 	if (reg < 0)
648 		goto out;
649 	if (!(reg & MCP794XX_BIT_ALMX_IF))
650 		goto out;
651 	reg &= ~MCP794XX_BIT_ALMX_IF;
652 	ret = i2c_smbus_write_byte_data(client, MCP794XX_REG_ALARM0_CTRL, reg);
653 	if (ret < 0)
654 		goto out;
655 
656 	/* Disable alarm 0. */
657 	reg = i2c_smbus_read_byte_data(client, MCP794XX_REG_CONTROL);
658 	if (reg < 0)
659 		goto out;
660 	reg &= ~MCP794XX_BIT_ALM0_EN;
661 	ret = i2c_smbus_write_byte_data(client, MCP794XX_REG_CONTROL, reg);
662 	if (ret < 0)
663 		goto out;
664 
665 	rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
666 
667 out:
668 	if (test_bit(HAS_ALARM, &ds1307->flags))
669 		enable_irq(client->irq);
670 	mutex_unlock(&ds1307->rtc->ops_lock);
671 }
672 
673 static int mcp794xx_read_alarm(struct device *dev, struct rtc_wkalrm *t)
674 {
675 	struct i2c_client *client = to_i2c_client(dev);
676 	struct ds1307 *ds1307 = i2c_get_clientdata(client);
677 	u8 *regs = ds1307->regs;
678 	int ret;
679 
680 	if (!test_bit(HAS_ALARM, &ds1307->flags))
681 		return -EINVAL;
682 
683 	/* Read control and alarm 0 registers. */
684 	ret = ds1307->read_block_data(client, MCP794XX_REG_CONTROL, 10, regs);
685 	if (ret < 0)
686 		return ret;
687 
688 	t->enabled = !!(regs[0] & MCP794XX_BIT_ALM0_EN);
689 
690 	/* Report alarm 0 time assuming 24-hour and day-of-month modes. */
691 	t->time.tm_sec = bcd2bin(ds1307->regs[3] & 0x7f);
692 	t->time.tm_min = bcd2bin(ds1307->regs[4] & 0x7f);
693 	t->time.tm_hour = bcd2bin(ds1307->regs[5] & 0x3f);
694 	t->time.tm_wday = bcd2bin(ds1307->regs[6] & 0x7) - 1;
695 	t->time.tm_mday = bcd2bin(ds1307->regs[7] & 0x3f);
696 	t->time.tm_mon = bcd2bin(ds1307->regs[8] & 0x1f) - 1;
697 	t->time.tm_year = -1;
698 	t->time.tm_yday = -1;
699 	t->time.tm_isdst = -1;
700 
701 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
702 		"enabled=%d polarity=%d irq=%d match=%d\n", __func__,
703 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
704 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled,
705 		!!(ds1307->regs[6] & MCP794XX_BIT_ALMX_POL),
706 		!!(ds1307->regs[6] & MCP794XX_BIT_ALMX_IF),
707 		(ds1307->regs[6] & MCP794XX_MSK_ALMX_MATCH) >> 4);
708 
709 	return 0;
710 }
711 
712 static int mcp794xx_set_alarm(struct device *dev, struct rtc_wkalrm *t)
713 {
714 	struct i2c_client *client = to_i2c_client(dev);
715 	struct ds1307 *ds1307 = i2c_get_clientdata(client);
716 	unsigned char *regs = ds1307->regs;
717 	int ret;
718 
719 	if (!test_bit(HAS_ALARM, &ds1307->flags))
720 		return -EINVAL;
721 
722 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
723 		"enabled=%d pending=%d\n", __func__,
724 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
725 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
726 		t->enabled, t->pending);
727 
728 	/* Read control and alarm 0 registers. */
729 	ret = ds1307->read_block_data(client, MCP794XX_REG_CONTROL, 10, regs);
730 	if (ret < 0)
731 		return ret;
732 
733 	/* Set alarm 0, using 24-hour and day-of-month modes. */
734 	regs[3] = bin2bcd(t->time.tm_sec);
735 	regs[4] = bin2bcd(t->time.tm_min);
736 	regs[5] = bin2bcd(t->time.tm_hour);
737 	regs[6] = bin2bcd(t->time.tm_wday) + 1;
738 	regs[7] = bin2bcd(t->time.tm_mday);
739 	regs[8] = bin2bcd(t->time.tm_mon) + 1;
740 
741 	/* Clear the alarm 0 interrupt flag. */
742 	regs[6] &= ~MCP794XX_BIT_ALMX_IF;
743 	/* Set alarm match: second, minute, hour, day, date, month. */
744 	regs[6] |= MCP794XX_MSK_ALMX_MATCH;
745 
746 	if (t->enabled)
747 		regs[0] |= MCP794XX_BIT_ALM0_EN;
748 	else
749 		regs[0] &= ~MCP794XX_BIT_ALM0_EN;
750 
751 	ret = ds1307->write_block_data(client, MCP794XX_REG_CONTROL, 10, regs);
752 	if (ret < 0)
753 		return ret;
754 
755 	return 0;
756 }
757 
758 static int mcp794xx_alarm_irq_enable(struct device *dev, unsigned int enabled)
759 {
760 	struct i2c_client *client = to_i2c_client(dev);
761 	struct ds1307 *ds1307 = i2c_get_clientdata(client);
762 	int reg;
763 
764 	if (!test_bit(HAS_ALARM, &ds1307->flags))
765 		return -EINVAL;
766 
767 	reg = i2c_smbus_read_byte_data(client, MCP794XX_REG_CONTROL);
768 	if (reg < 0)
769 		return reg;
770 
771 	if (enabled)
772 		reg |= MCP794XX_BIT_ALM0_EN;
773 	else
774 		reg &= ~MCP794XX_BIT_ALM0_EN;
775 
776 	return i2c_smbus_write_byte_data(client, MCP794XX_REG_CONTROL, reg);
777 }
778 
779 static const struct rtc_class_ops mcp794xx_rtc_ops = {
780 	.read_time	= ds1307_get_time,
781 	.set_time	= ds1307_set_time,
782 	.read_alarm	= mcp794xx_read_alarm,
783 	.set_alarm	= mcp794xx_set_alarm,
784 	.alarm_irq_enable = mcp794xx_alarm_irq_enable,
785 };
786 
787 /*----------------------------------------------------------------------*/
788 
789 static ssize_t
790 ds1307_nvram_read(struct file *filp, struct kobject *kobj,
791 		struct bin_attribute *attr,
792 		char *buf, loff_t off, size_t count)
793 {
794 	struct i2c_client	*client;
795 	struct ds1307		*ds1307;
796 	int			result;
797 
798 	client = kobj_to_i2c_client(kobj);
799 	ds1307 = i2c_get_clientdata(client);
800 
801 	if (unlikely(off >= ds1307->nvram->size))
802 		return 0;
803 	if ((off + count) > ds1307->nvram->size)
804 		count = ds1307->nvram->size - off;
805 	if (unlikely(!count))
806 		return count;
807 
808 	result = ds1307->read_block_data(client, ds1307->nvram_offset + off,
809 								count, buf);
810 	if (result < 0)
811 		dev_err(&client->dev, "%s error %d\n", "nvram read", result);
812 	return result;
813 }
814 
815 static ssize_t
816 ds1307_nvram_write(struct file *filp, struct kobject *kobj,
817 		struct bin_attribute *attr,
818 		char *buf, loff_t off, size_t count)
819 {
820 	struct i2c_client	*client;
821 	struct ds1307		*ds1307;
822 	int			result;
823 
824 	client = kobj_to_i2c_client(kobj);
825 	ds1307 = i2c_get_clientdata(client);
826 
827 	if (unlikely(off >= ds1307->nvram->size))
828 		return -EFBIG;
829 	if ((off + count) > ds1307->nvram->size)
830 		count = ds1307->nvram->size - off;
831 	if (unlikely(!count))
832 		return count;
833 
834 	result = ds1307->write_block_data(client, ds1307->nvram_offset + off,
835 								count, buf);
836 	if (result < 0) {
837 		dev_err(&client->dev, "%s error %d\n", "nvram write", result);
838 		return result;
839 	}
840 	return count;
841 }
842 
843 
844 /*----------------------------------------------------------------------*/
845 
846 static u8 do_trickle_setup_ds1339(struct i2c_client *client,
847 				  uint32_t ohms, bool diode)
848 {
849 	u8 setup = (diode) ? DS1307_TRICKLE_CHARGER_DIODE :
850 		DS1307_TRICKLE_CHARGER_NO_DIODE;
851 
852 	switch (ohms) {
853 	case 250:
854 		setup |= DS1307_TRICKLE_CHARGER_250_OHM;
855 		break;
856 	case 2000:
857 		setup |= DS1307_TRICKLE_CHARGER_2K_OHM;
858 		break;
859 	case 4000:
860 		setup |= DS1307_TRICKLE_CHARGER_4K_OHM;
861 		break;
862 	default:
863 		dev_warn(&client->dev,
864 			 "Unsupported ohm value %u in dt\n", ohms);
865 		return 0;
866 	}
867 	return setup;
868 }
869 
870 static void ds1307_trickle_of_init(struct i2c_client *client,
871 				   struct chip_desc *chip)
872 {
873 	uint32_t ohms = 0;
874 	bool diode = true;
875 
876 	if (!chip->do_trickle_setup)
877 		goto out;
878 	if (of_property_read_u32(client->dev.of_node, "trickle-resistor-ohms" , &ohms))
879 		goto out;
880 	if (of_property_read_bool(client->dev.of_node, "trickle-diode-disable"))
881 		diode = false;
882 	chip->trickle_charger_setup = chip->do_trickle_setup(client,
883 							     ohms, diode);
884 out:
885 	return;
886 }
887 
888 static int ds1307_probe(struct i2c_client *client,
889 			const struct i2c_device_id *id)
890 {
891 	struct ds1307		*ds1307;
892 	int			err = -ENODEV;
893 	int			tmp;
894 	struct chip_desc	*chip = &chips[id->driver_data];
895 	struct i2c_adapter	*adapter = to_i2c_adapter(client->dev.parent);
896 	bool			want_irq = false;
897 	unsigned char		*buf;
898 	struct ds1307_platform_data *pdata = dev_get_platdata(&client->dev);
899 	static const int	bbsqi_bitpos[] = {
900 		[ds_1337] = 0,
901 		[ds_1339] = DS1339_BIT_BBSQI,
902 		[ds_3231] = DS3231_BIT_BBSQW,
903 	};
904 	const struct rtc_class_ops *rtc_ops = &ds13xx_rtc_ops;
905 
906 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)
907 	    && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
908 		return -EIO;
909 
910 	ds1307 = devm_kzalloc(&client->dev, sizeof(struct ds1307), GFP_KERNEL);
911 	if (!ds1307)
912 		return -ENOMEM;
913 
914 	i2c_set_clientdata(client, ds1307);
915 
916 	ds1307->client	= client;
917 	ds1307->type	= id->driver_data;
918 
919 	if (!pdata && client->dev.of_node)
920 		ds1307_trickle_of_init(client, chip);
921 	else if (pdata && pdata->trickle_charger_setup)
922 		chip->trickle_charger_setup = pdata->trickle_charger_setup;
923 
924 	if (chip->trickle_charger_setup && chip->trickle_charger_reg) {
925 		dev_dbg(&client->dev, "writing trickle charger info 0x%x to 0x%x\n",
926 		    DS13XX_TRICKLE_CHARGER_MAGIC | chip->trickle_charger_setup,
927 		    chip->trickle_charger_reg);
928 		i2c_smbus_write_byte_data(client, chip->trickle_charger_reg,
929 		    DS13XX_TRICKLE_CHARGER_MAGIC |
930 		    chip->trickle_charger_setup);
931 	}
932 
933 	buf = ds1307->regs;
934 	if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
935 		ds1307->read_block_data = ds1307_native_smbus_read_block_data;
936 		ds1307->write_block_data = ds1307_native_smbus_write_block_data;
937 	} else {
938 		ds1307->read_block_data = ds1307_read_block_data;
939 		ds1307->write_block_data = ds1307_write_block_data;
940 	}
941 
942 	switch (ds1307->type) {
943 	case ds_1337:
944 	case ds_1339:
945 	case ds_3231:
946 		/* get registers that the "rtc" read below won't read... */
947 		tmp = ds1307->read_block_data(ds1307->client,
948 				DS1337_REG_CONTROL, 2, buf);
949 		if (tmp != 2) {
950 			dev_dbg(&client->dev, "read error %d\n", tmp);
951 			err = -EIO;
952 			goto exit;
953 		}
954 
955 		/* oscillator off?  turn it on, so clock can tick. */
956 		if (ds1307->regs[0] & DS1337_BIT_nEOSC)
957 			ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
958 
959 		/*
960 		 * Using IRQ?  Disable the square wave and both alarms.
961 		 * For some variants, be sure alarms can trigger when we're
962 		 * running on Vbackup (BBSQI/BBSQW)
963 		 */
964 		if (ds1307->client->irq > 0 && chip->alarm) {
965 			INIT_WORK(&ds1307->work, ds1307_work);
966 
967 			ds1307->regs[0] |= DS1337_BIT_INTCN
968 					| bbsqi_bitpos[ds1307->type];
969 			ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
970 
971 			want_irq = true;
972 		}
973 
974 		i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
975 							ds1307->regs[0]);
976 
977 		/* oscillator fault?  clear flag, and warn */
978 		if (ds1307->regs[1] & DS1337_BIT_OSF) {
979 			i2c_smbus_write_byte_data(client, DS1337_REG_STATUS,
980 				ds1307->regs[1] & ~DS1337_BIT_OSF);
981 			dev_warn(&client->dev, "SET TIME!\n");
982 		}
983 		break;
984 
985 	case rx_8025:
986 		tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
987 				RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
988 		if (tmp != 2) {
989 			dev_dbg(&client->dev, "read error %d\n", tmp);
990 			err = -EIO;
991 			goto exit;
992 		}
993 
994 		/* oscillator off?  turn it on, so clock can tick. */
995 		if (!(ds1307->regs[1] & RX8025_BIT_XST)) {
996 			ds1307->regs[1] |= RX8025_BIT_XST;
997 			i2c_smbus_write_byte_data(client,
998 						  RX8025_REG_CTRL2 << 4 | 0x08,
999 						  ds1307->regs[1]);
1000 			dev_warn(&client->dev,
1001 				 "oscillator stop detected - SET TIME!\n");
1002 		}
1003 
1004 		if (ds1307->regs[1] & RX8025_BIT_PON) {
1005 			ds1307->regs[1] &= ~RX8025_BIT_PON;
1006 			i2c_smbus_write_byte_data(client,
1007 						  RX8025_REG_CTRL2 << 4 | 0x08,
1008 						  ds1307->regs[1]);
1009 			dev_warn(&client->dev, "power-on detected\n");
1010 		}
1011 
1012 		if (ds1307->regs[1] & RX8025_BIT_VDET) {
1013 			ds1307->regs[1] &= ~RX8025_BIT_VDET;
1014 			i2c_smbus_write_byte_data(client,
1015 						  RX8025_REG_CTRL2 << 4 | 0x08,
1016 						  ds1307->regs[1]);
1017 			dev_warn(&client->dev, "voltage drop detected\n");
1018 		}
1019 
1020 		/* make sure we are running in 24hour mode */
1021 		if (!(ds1307->regs[0] & RX8025_BIT_2412)) {
1022 			u8 hour;
1023 
1024 			/* switch to 24 hour mode */
1025 			i2c_smbus_write_byte_data(client,
1026 						  RX8025_REG_CTRL1 << 4 | 0x08,
1027 						  ds1307->regs[0] |
1028 						  RX8025_BIT_2412);
1029 
1030 			tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
1031 					RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
1032 			if (tmp != 2) {
1033 				dev_dbg(&client->dev, "read error %d\n", tmp);
1034 				err = -EIO;
1035 				goto exit;
1036 			}
1037 
1038 			/* correct hour */
1039 			hour = bcd2bin(ds1307->regs[DS1307_REG_HOUR]);
1040 			if (hour == 12)
1041 				hour = 0;
1042 			if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1043 				hour += 12;
1044 
1045 			i2c_smbus_write_byte_data(client,
1046 						  DS1307_REG_HOUR << 4 | 0x08,
1047 						  hour);
1048 		}
1049 		break;
1050 	case ds_1388:
1051 		ds1307->offset = 1; /* Seconds starts at 1 */
1052 		break;
1053 	case mcp794xx:
1054 		rtc_ops = &mcp794xx_rtc_ops;
1055 		if (ds1307->client->irq > 0 && chip->alarm) {
1056 			INIT_WORK(&ds1307->work, mcp794xx_work);
1057 			want_irq = true;
1058 		}
1059 		break;
1060 	default:
1061 		break;
1062 	}
1063 
1064 read_rtc:
1065 	/* read RTC registers */
1066 	tmp = ds1307->read_block_data(ds1307->client, ds1307->offset, 8, buf);
1067 	if (tmp != 8) {
1068 		dev_dbg(&client->dev, "read error %d\n", tmp);
1069 		err = -EIO;
1070 		goto exit;
1071 	}
1072 
1073 	/*
1074 	 * minimal sanity checking; some chips (like DS1340) don't
1075 	 * specify the extra bits as must-be-zero, but there are
1076 	 * still a few values that are clearly out-of-range.
1077 	 */
1078 	tmp = ds1307->regs[DS1307_REG_SECS];
1079 	switch (ds1307->type) {
1080 	case ds_1307:
1081 	case m41t00:
1082 		/* clock halted?  turn it on, so clock can tick. */
1083 		if (tmp & DS1307_BIT_CH) {
1084 			i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
1085 			dev_warn(&client->dev, "SET TIME!\n");
1086 			goto read_rtc;
1087 		}
1088 		break;
1089 	case ds_1338:
1090 		/* clock halted?  turn it on, so clock can tick. */
1091 		if (tmp & DS1307_BIT_CH)
1092 			i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
1093 
1094 		/* oscillator fault?  clear flag, and warn */
1095 		if (ds1307->regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
1096 			i2c_smbus_write_byte_data(client, DS1307_REG_CONTROL,
1097 					ds1307->regs[DS1307_REG_CONTROL]
1098 					& ~DS1338_BIT_OSF);
1099 			dev_warn(&client->dev, "SET TIME!\n");
1100 			goto read_rtc;
1101 		}
1102 		break;
1103 	case ds_1340:
1104 		/* clock halted?  turn it on, so clock can tick. */
1105 		if (tmp & DS1340_BIT_nEOSC)
1106 			i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
1107 
1108 		tmp = i2c_smbus_read_byte_data(client, DS1340_REG_FLAG);
1109 		if (tmp < 0) {
1110 			dev_dbg(&client->dev, "read error %d\n", tmp);
1111 			err = -EIO;
1112 			goto exit;
1113 		}
1114 
1115 		/* oscillator fault?  clear flag, and warn */
1116 		if (tmp & DS1340_BIT_OSF) {
1117 			i2c_smbus_write_byte_data(client, DS1340_REG_FLAG, 0);
1118 			dev_warn(&client->dev, "SET TIME!\n");
1119 		}
1120 		break;
1121 	case mcp794xx:
1122 		/* make sure that the backup battery is enabled */
1123 		if (!(ds1307->regs[DS1307_REG_WDAY] & MCP794XX_BIT_VBATEN)) {
1124 			i2c_smbus_write_byte_data(client, DS1307_REG_WDAY,
1125 					ds1307->regs[DS1307_REG_WDAY]
1126 					| MCP794XX_BIT_VBATEN);
1127 		}
1128 
1129 		/* clock halted?  turn it on, so clock can tick. */
1130 		if (!(tmp & MCP794XX_BIT_ST)) {
1131 			i2c_smbus_write_byte_data(client, DS1307_REG_SECS,
1132 					MCP794XX_BIT_ST);
1133 			dev_warn(&client->dev, "SET TIME!\n");
1134 			goto read_rtc;
1135 		}
1136 
1137 		break;
1138 	default:
1139 		break;
1140 	}
1141 
1142 	tmp = ds1307->regs[DS1307_REG_HOUR];
1143 	switch (ds1307->type) {
1144 	case ds_1340:
1145 	case m41t00:
1146 		/*
1147 		 * NOTE: ignores century bits; fix before deploying
1148 		 * systems that will run through year 2100.
1149 		 */
1150 		break;
1151 	case rx_8025:
1152 		break;
1153 	default:
1154 		if (!(tmp & DS1307_BIT_12HR))
1155 			break;
1156 
1157 		/*
1158 		 * Be sure we're in 24 hour mode.  Multi-master systems
1159 		 * take note...
1160 		 */
1161 		tmp = bcd2bin(tmp & 0x1f);
1162 		if (tmp == 12)
1163 			tmp = 0;
1164 		if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1165 			tmp += 12;
1166 		i2c_smbus_write_byte_data(client,
1167 				ds1307->offset + DS1307_REG_HOUR,
1168 				bin2bcd(tmp));
1169 	}
1170 
1171 	device_set_wakeup_capable(&client->dev, want_irq);
1172 	ds1307->rtc = devm_rtc_device_register(&client->dev, client->name,
1173 				rtc_ops, THIS_MODULE);
1174 	if (IS_ERR(ds1307->rtc)) {
1175 		return PTR_ERR(ds1307->rtc);
1176 	}
1177 
1178 	if (want_irq) {
1179 		err = request_irq(client->irq, ds1307_irq, IRQF_SHARED,
1180 			  ds1307->rtc->name, client);
1181 		if (err) {
1182 			client->irq = 0;
1183 			dev_err(&client->dev, "unable to request IRQ!\n");
1184 		} else {
1185 
1186 			set_bit(HAS_ALARM, &ds1307->flags);
1187 			dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
1188 		}
1189 	}
1190 
1191 	if (chip->nvram_size) {
1192 
1193 		ds1307->nvram = devm_kzalloc(&client->dev,
1194 					sizeof(struct bin_attribute),
1195 					GFP_KERNEL);
1196 		if (!ds1307->nvram) {
1197 			dev_err(&client->dev, "cannot allocate memory for nvram sysfs\n");
1198 		} else {
1199 
1200 			ds1307->nvram->attr.name = "nvram";
1201 			ds1307->nvram->attr.mode = S_IRUGO | S_IWUSR;
1202 
1203 			sysfs_bin_attr_init(ds1307->nvram);
1204 
1205 			ds1307->nvram->read = ds1307_nvram_read;
1206 			ds1307->nvram->write = ds1307_nvram_write;
1207 			ds1307->nvram->size = chip->nvram_size;
1208 			ds1307->nvram_offset = chip->nvram_offset;
1209 
1210 			err = sysfs_create_bin_file(&client->dev.kobj,
1211 						    ds1307->nvram);
1212 			if (err) {
1213 				dev_err(&client->dev,
1214 					"unable to create sysfs file: %s\n",
1215 					ds1307->nvram->attr.name);
1216 			} else {
1217 				set_bit(HAS_NVRAM, &ds1307->flags);
1218 				dev_info(&client->dev, "%zu bytes nvram\n",
1219 					 ds1307->nvram->size);
1220 			}
1221 		}
1222 	}
1223 
1224 	return 0;
1225 
1226 exit:
1227 	return err;
1228 }
1229 
1230 static int ds1307_remove(struct i2c_client *client)
1231 {
1232 	struct ds1307 *ds1307 = i2c_get_clientdata(client);
1233 
1234 	if (test_and_clear_bit(HAS_ALARM, &ds1307->flags)) {
1235 		free_irq(client->irq, client);
1236 		cancel_work_sync(&ds1307->work);
1237 	}
1238 
1239 	if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags))
1240 		sysfs_remove_bin_file(&client->dev.kobj, ds1307->nvram);
1241 
1242 	return 0;
1243 }
1244 
1245 static struct i2c_driver ds1307_driver = {
1246 	.driver = {
1247 		.name	= "rtc-ds1307",
1248 		.owner	= THIS_MODULE,
1249 	},
1250 	.probe		= ds1307_probe,
1251 	.remove		= ds1307_remove,
1252 	.id_table	= ds1307_id,
1253 };
1254 
1255 module_i2c_driver(ds1307_driver);
1256 
1257 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
1258 MODULE_LICENSE("GPL");
1259