xref: /openbmc/linux/drivers/rtc/rtc-ds1307.c (revision e15a5365)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * rtc-ds1307.c - RTC driver for some mostly-compatible I2C chips.
4  *
5  *  Copyright (C) 2005 James Chapman (ds1337 core)
6  *  Copyright (C) 2006 David Brownell
7  *  Copyright (C) 2009 Matthias Fuchs (rx8025 support)
8  *  Copyright (C) 2012 Bertrand Achard (nvram access fixes)
9  */
10 
11 #include <linux/acpi.h>
12 #include <linux/bcd.h>
13 #include <linux/i2c.h>
14 #include <linux/init.h>
15 #include <linux/module.h>
16 #include <linux/of_device.h>
17 #include <linux/rtc/ds1307.h>
18 #include <linux/rtc.h>
19 #include <linux/slab.h>
20 #include <linux/string.h>
21 #include <linux/hwmon.h>
22 #include <linux/hwmon-sysfs.h>
23 #include <linux/clk-provider.h>
24 #include <linux/regmap.h>
25 #include <linux/watchdog.h>
26 
27 /*
28  * We can't determine type by probing, but if we expect pre-Linux code
29  * to have set the chip up as a clock (turning on the oscillator and
30  * setting the date and time), Linux can ignore the non-clock features.
31  * That's a natural job for a factory or repair bench.
32  */
33 enum ds_type {
34 	ds_1307,
35 	ds_1308,
36 	ds_1337,
37 	ds_1338,
38 	ds_1339,
39 	ds_1340,
40 	ds_1341,
41 	ds_1388,
42 	ds_3231,
43 	m41t0,
44 	m41t00,
45 	m41t11,
46 	mcp794xx,
47 	rx_8025,
48 	rx_8130,
49 	last_ds_type /* always last */
50 	/* rs5c372 too?  different address... */
51 };
52 
53 /* RTC registers don't differ much, except for the century flag */
54 #define DS1307_REG_SECS		0x00	/* 00-59 */
55 #	define DS1307_BIT_CH		0x80
56 #	define DS1340_BIT_nEOSC		0x80
57 #	define MCP794XX_BIT_ST		0x80
58 #define DS1307_REG_MIN		0x01	/* 00-59 */
59 #	define M41T0_BIT_OF		0x80
60 #define DS1307_REG_HOUR		0x02	/* 00-23, or 1-12{am,pm} */
61 #	define DS1307_BIT_12HR		0x40	/* in REG_HOUR */
62 #	define DS1307_BIT_PM		0x20	/* in REG_HOUR */
63 #	define DS1340_BIT_CENTURY_EN	0x80	/* in REG_HOUR */
64 #	define DS1340_BIT_CENTURY	0x40	/* in REG_HOUR */
65 #define DS1307_REG_WDAY		0x03	/* 01-07 */
66 #	define MCP794XX_BIT_VBATEN	0x08
67 #define DS1307_REG_MDAY		0x04	/* 01-31 */
68 #define DS1307_REG_MONTH	0x05	/* 01-12 */
69 #	define DS1337_BIT_CENTURY	0x80	/* in REG_MONTH */
70 #define DS1307_REG_YEAR		0x06	/* 00-99 */
71 
72 /*
73  * Other registers (control, status, alarms, trickle charge, NVRAM, etc)
74  * start at 7, and they differ a LOT. Only control and status matter for
75  * basic RTC date and time functionality; be careful using them.
76  */
77 #define DS1307_REG_CONTROL	0x07		/* or ds1338 */
78 #	define DS1307_BIT_OUT		0x80
79 #	define DS1338_BIT_OSF		0x20
80 #	define DS1307_BIT_SQWE		0x10
81 #	define DS1307_BIT_RS1		0x02
82 #	define DS1307_BIT_RS0		0x01
83 #define DS1337_REG_CONTROL	0x0e
84 #	define DS1337_BIT_nEOSC		0x80
85 #	define DS1339_BIT_BBSQI		0x20
86 #	define DS3231_BIT_BBSQW		0x40 /* same as BBSQI */
87 #	define DS1337_BIT_RS2		0x10
88 #	define DS1337_BIT_RS1		0x08
89 #	define DS1337_BIT_INTCN		0x04
90 #	define DS1337_BIT_A2IE		0x02
91 #	define DS1337_BIT_A1IE		0x01
92 #define DS1340_REG_CONTROL	0x07
93 #	define DS1340_BIT_OUT		0x80
94 #	define DS1340_BIT_FT		0x40
95 #	define DS1340_BIT_CALIB_SIGN	0x20
96 #	define DS1340_M_CALIBRATION	0x1f
97 #define DS1340_REG_FLAG		0x09
98 #	define DS1340_BIT_OSF		0x80
99 #define DS1337_REG_STATUS	0x0f
100 #	define DS1337_BIT_OSF		0x80
101 #	define DS3231_BIT_EN32KHZ	0x08
102 #	define DS1337_BIT_A2I		0x02
103 #	define DS1337_BIT_A1I		0x01
104 #define DS1339_REG_ALARM1_SECS	0x07
105 
106 #define DS13XX_TRICKLE_CHARGER_MAGIC	0xa0
107 
108 #define RX8025_REG_CTRL1	0x0e
109 #	define RX8025_BIT_2412		0x20
110 #define RX8025_REG_CTRL2	0x0f
111 #	define RX8025_BIT_PON		0x10
112 #	define RX8025_BIT_VDET		0x40
113 #	define RX8025_BIT_XST		0x20
114 
115 #define RX8130_REG_ALARM_MIN		0x17
116 #define RX8130_REG_ALARM_HOUR		0x18
117 #define RX8130_REG_ALARM_WEEK_OR_DAY	0x19
118 #define RX8130_REG_EXTENSION		0x1c
119 #define RX8130_REG_EXTENSION_WADA	BIT(3)
120 #define RX8130_REG_FLAG			0x1d
121 #define RX8130_REG_FLAG_VLF		BIT(1)
122 #define RX8130_REG_FLAG_AF		BIT(3)
123 #define RX8130_REG_CONTROL0		0x1e
124 #define RX8130_REG_CONTROL0_AIE		BIT(3)
125 #define RX8130_REG_CONTROL1		0x1f
126 #define RX8130_REG_CONTROL1_INIEN	BIT(4)
127 #define RX8130_REG_CONTROL1_CHGEN	BIT(5)
128 
129 #define MCP794XX_REG_CONTROL		0x07
130 #	define MCP794XX_BIT_ALM0_EN	0x10
131 #	define MCP794XX_BIT_ALM1_EN	0x20
132 #define MCP794XX_REG_ALARM0_BASE	0x0a
133 #define MCP794XX_REG_ALARM0_CTRL	0x0d
134 #define MCP794XX_REG_ALARM1_BASE	0x11
135 #define MCP794XX_REG_ALARM1_CTRL	0x14
136 #	define MCP794XX_BIT_ALMX_IF	BIT(3)
137 #	define MCP794XX_BIT_ALMX_C0	BIT(4)
138 #	define MCP794XX_BIT_ALMX_C1	BIT(5)
139 #	define MCP794XX_BIT_ALMX_C2	BIT(6)
140 #	define MCP794XX_BIT_ALMX_POL	BIT(7)
141 #	define MCP794XX_MSK_ALMX_MATCH	(MCP794XX_BIT_ALMX_C0 | \
142 					 MCP794XX_BIT_ALMX_C1 | \
143 					 MCP794XX_BIT_ALMX_C2)
144 
145 #define M41TXX_REG_CONTROL	0x07
146 #	define M41TXX_BIT_OUT		BIT(7)
147 #	define M41TXX_BIT_FT		BIT(6)
148 #	define M41TXX_BIT_CALIB_SIGN	BIT(5)
149 #	define M41TXX_M_CALIBRATION	GENMASK(4, 0)
150 
151 #define DS1388_REG_WDOG_HUN_SECS	0x08
152 #define DS1388_REG_WDOG_SECS		0x09
153 #define DS1388_REG_FLAG			0x0b
154 #	define DS1388_BIT_WF		BIT(6)
155 #	define DS1388_BIT_OSF		BIT(7)
156 #define DS1388_REG_CONTROL		0x0c
157 #	define DS1388_BIT_RST		BIT(0)
158 #	define DS1388_BIT_WDE		BIT(1)
159 #	define DS1388_BIT_nEOSC		BIT(7)
160 
161 /* negative offset step is -2.034ppm */
162 #define M41TXX_NEG_OFFSET_STEP_PPB	2034
163 /* positive offset step is +4.068ppm */
164 #define M41TXX_POS_OFFSET_STEP_PPB	4068
165 /* Min and max values supported with 'offset' interface by M41TXX */
166 #define M41TXX_MIN_OFFSET	((-31) * M41TXX_NEG_OFFSET_STEP_PPB)
167 #define M41TXX_MAX_OFFSET	((31) * M41TXX_POS_OFFSET_STEP_PPB)
168 
169 struct ds1307 {
170 	enum ds_type		type;
171 	unsigned long		flags;
172 #define HAS_NVRAM	0		/* bit 0 == sysfs file active */
173 #define HAS_ALARM	1		/* bit 1 == irq claimed */
174 	struct device		*dev;
175 	struct regmap		*regmap;
176 	const char		*name;
177 	struct rtc_device	*rtc;
178 #ifdef CONFIG_COMMON_CLK
179 	struct clk_hw		clks[2];
180 #endif
181 };
182 
183 struct chip_desc {
184 	unsigned		alarm:1;
185 	u16			nvram_offset;
186 	u16			nvram_size;
187 	u8			offset; /* register's offset */
188 	u8			century_reg;
189 	u8			century_enable_bit;
190 	u8			century_bit;
191 	u8			bbsqi_bit;
192 	irq_handler_t		irq_handler;
193 	const struct rtc_class_ops *rtc_ops;
194 	u16			trickle_charger_reg;
195 	u8			(*do_trickle_setup)(struct ds1307 *, u32,
196 						    bool);
197 	/* Does the RTC require trickle-resistor-ohms to select the value of
198 	 * the resistor between Vcc and Vbackup?
199 	 */
200 	bool			requires_trickle_resistor;
201 	/* Some RTC's batteries and supercaps were charged by default, others
202 	 * allow charging but were not configured previously to do so.
203 	 * Remember this behavior to stay backwards compatible.
204 	 */
205 	bool			charge_default;
206 };
207 
208 static const struct chip_desc chips[last_ds_type];
209 
210 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
211 {
212 	struct ds1307	*ds1307 = dev_get_drvdata(dev);
213 	int		tmp, ret;
214 	const struct chip_desc *chip = &chips[ds1307->type];
215 	u8 regs[7];
216 
217 	if (ds1307->type == rx_8130) {
218 		unsigned int regflag;
219 		ret = regmap_read(ds1307->regmap, RX8130_REG_FLAG, &regflag);
220 		if (ret) {
221 			dev_err(dev, "%s error %d\n", "read", ret);
222 			return ret;
223 		}
224 
225 		if (regflag & RX8130_REG_FLAG_VLF) {
226 			dev_warn_once(dev, "oscillator failed, set time!\n");
227 			return -EINVAL;
228 		}
229 	}
230 
231 	/* read the RTC date and time registers all at once */
232 	ret = regmap_bulk_read(ds1307->regmap, chip->offset, regs,
233 			       sizeof(regs));
234 	if (ret) {
235 		dev_err(dev, "%s error %d\n", "read", ret);
236 		return ret;
237 	}
238 
239 	dev_dbg(dev, "%s: %7ph\n", "read", regs);
240 
241 	/* if oscillator fail bit is set, no data can be trusted */
242 	if (ds1307->type == m41t0 &&
243 	    regs[DS1307_REG_MIN] & M41T0_BIT_OF) {
244 		dev_warn_once(dev, "oscillator failed, set time!\n");
245 		return -EINVAL;
246 	}
247 
248 	tmp = regs[DS1307_REG_SECS];
249 	switch (ds1307->type) {
250 	case ds_1307:
251 	case m41t0:
252 	case m41t00:
253 	case m41t11:
254 		if (tmp & DS1307_BIT_CH)
255 			return -EINVAL;
256 		break;
257 	case ds_1308:
258 	case ds_1338:
259 		if (tmp & DS1307_BIT_CH)
260 			return -EINVAL;
261 
262 		ret = regmap_read(ds1307->regmap, DS1307_REG_CONTROL, &tmp);
263 		if (ret)
264 			return ret;
265 		if (tmp & DS1338_BIT_OSF)
266 			return -EINVAL;
267 		break;
268 	case ds_1340:
269 		if (tmp & DS1340_BIT_nEOSC)
270 			return -EINVAL;
271 
272 		ret = regmap_read(ds1307->regmap, DS1340_REG_FLAG, &tmp);
273 		if (ret)
274 			return ret;
275 		if (tmp & DS1340_BIT_OSF)
276 			return -EINVAL;
277 		break;
278 	case ds_1388:
279 		ret = regmap_read(ds1307->regmap, DS1388_REG_FLAG, &tmp);
280 		if (ret)
281 			return ret;
282 		if (tmp & DS1388_BIT_OSF)
283 			return -EINVAL;
284 		break;
285 	case mcp794xx:
286 		if (!(tmp & MCP794XX_BIT_ST))
287 			return -EINVAL;
288 
289 		break;
290 	default:
291 		break;
292 	}
293 
294 	t->tm_sec = bcd2bin(regs[DS1307_REG_SECS] & 0x7f);
295 	t->tm_min = bcd2bin(regs[DS1307_REG_MIN] & 0x7f);
296 	tmp = regs[DS1307_REG_HOUR] & 0x3f;
297 	t->tm_hour = bcd2bin(tmp);
298 	t->tm_wday = bcd2bin(regs[DS1307_REG_WDAY] & 0x07) - 1;
299 	t->tm_mday = bcd2bin(regs[DS1307_REG_MDAY] & 0x3f);
300 	tmp = regs[DS1307_REG_MONTH] & 0x1f;
301 	t->tm_mon = bcd2bin(tmp) - 1;
302 	t->tm_year = bcd2bin(regs[DS1307_REG_YEAR]) + 100;
303 
304 	if (regs[chip->century_reg] & chip->century_bit &&
305 	    IS_ENABLED(CONFIG_RTC_DRV_DS1307_CENTURY))
306 		t->tm_year += 100;
307 
308 	dev_dbg(dev, "%s secs=%d, mins=%d, "
309 		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
310 		"read", t->tm_sec, t->tm_min,
311 		t->tm_hour, t->tm_mday,
312 		t->tm_mon, t->tm_year, t->tm_wday);
313 
314 	return 0;
315 }
316 
317 static int ds1307_set_time(struct device *dev, struct rtc_time *t)
318 {
319 	struct ds1307	*ds1307 = dev_get_drvdata(dev);
320 	const struct chip_desc *chip = &chips[ds1307->type];
321 	int		result;
322 	int		tmp;
323 	u8		regs[7];
324 
325 	dev_dbg(dev, "%s secs=%d, mins=%d, "
326 		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
327 		"write", t->tm_sec, t->tm_min,
328 		t->tm_hour, t->tm_mday,
329 		t->tm_mon, t->tm_year, t->tm_wday);
330 
331 	if (t->tm_year < 100)
332 		return -EINVAL;
333 
334 #ifdef CONFIG_RTC_DRV_DS1307_CENTURY
335 	if (t->tm_year > (chip->century_bit ? 299 : 199))
336 		return -EINVAL;
337 #else
338 	if (t->tm_year > 199)
339 		return -EINVAL;
340 #endif
341 
342 	regs[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
343 	regs[DS1307_REG_MIN] = bin2bcd(t->tm_min);
344 	regs[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
345 	regs[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
346 	regs[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
347 	regs[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
348 
349 	/* assume 20YY not 19YY */
350 	tmp = t->tm_year - 100;
351 	regs[DS1307_REG_YEAR] = bin2bcd(tmp);
352 
353 	if (chip->century_enable_bit)
354 		regs[chip->century_reg] |= chip->century_enable_bit;
355 	if (t->tm_year > 199 && chip->century_bit)
356 		regs[chip->century_reg] |= chip->century_bit;
357 
358 	switch (ds1307->type) {
359 	case ds_1308:
360 	case ds_1338:
361 		regmap_update_bits(ds1307->regmap, DS1307_REG_CONTROL,
362 				   DS1338_BIT_OSF, 0);
363 		break;
364 	case ds_1340:
365 		regmap_update_bits(ds1307->regmap, DS1340_REG_FLAG,
366 				   DS1340_BIT_OSF, 0);
367 		break;
368 	case ds_1388:
369 		regmap_update_bits(ds1307->regmap, DS1388_REG_FLAG,
370 				   DS1388_BIT_OSF, 0);
371 		break;
372 	case mcp794xx:
373 		/*
374 		 * these bits were cleared when preparing the date/time
375 		 * values and need to be set again before writing the
376 		 * regsfer out to the device.
377 		 */
378 		regs[DS1307_REG_SECS] |= MCP794XX_BIT_ST;
379 		regs[DS1307_REG_WDAY] |= MCP794XX_BIT_VBATEN;
380 		break;
381 	default:
382 		break;
383 	}
384 
385 	dev_dbg(dev, "%s: %7ph\n", "write", regs);
386 
387 	result = regmap_bulk_write(ds1307->regmap, chip->offset, regs,
388 				   sizeof(regs));
389 	if (result) {
390 		dev_err(dev, "%s error %d\n", "write", result);
391 		return result;
392 	}
393 
394 	if (ds1307->type == rx_8130) {
395 		/* clear Voltage Loss Flag as data is available now */
396 		result = regmap_write(ds1307->regmap, RX8130_REG_FLAG,
397 				      ~(u8)RX8130_REG_FLAG_VLF);
398 		if (result) {
399 			dev_err(dev, "%s error %d\n", "write", result);
400 			return result;
401 		}
402 	}
403 
404 	return 0;
405 }
406 
407 static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
408 {
409 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
410 	int			ret;
411 	u8			regs[9];
412 
413 	if (!test_bit(HAS_ALARM, &ds1307->flags))
414 		return -EINVAL;
415 
416 	/* read all ALARM1, ALARM2, and status registers at once */
417 	ret = regmap_bulk_read(ds1307->regmap, DS1339_REG_ALARM1_SECS,
418 			       regs, sizeof(regs));
419 	if (ret) {
420 		dev_err(dev, "%s error %d\n", "alarm read", ret);
421 		return ret;
422 	}
423 
424 	dev_dbg(dev, "%s: %4ph, %3ph, %2ph\n", "alarm read",
425 		&regs[0], &regs[4], &regs[7]);
426 
427 	/*
428 	 * report alarm time (ALARM1); assume 24 hour and day-of-month modes,
429 	 * and that all four fields are checked matches
430 	 */
431 	t->time.tm_sec = bcd2bin(regs[0] & 0x7f);
432 	t->time.tm_min = bcd2bin(regs[1] & 0x7f);
433 	t->time.tm_hour = bcd2bin(regs[2] & 0x3f);
434 	t->time.tm_mday = bcd2bin(regs[3] & 0x3f);
435 
436 	/* ... and status */
437 	t->enabled = !!(regs[7] & DS1337_BIT_A1IE);
438 	t->pending = !!(regs[8] & DS1337_BIT_A1I);
439 
440 	dev_dbg(dev, "%s secs=%d, mins=%d, "
441 		"hours=%d, mday=%d, enabled=%d, pending=%d\n",
442 		"alarm read", t->time.tm_sec, t->time.tm_min,
443 		t->time.tm_hour, t->time.tm_mday,
444 		t->enabled, t->pending);
445 
446 	return 0;
447 }
448 
449 static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
450 {
451 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
452 	unsigned char		regs[9];
453 	u8			control, status;
454 	int			ret;
455 
456 	if (!test_bit(HAS_ALARM, &ds1307->flags))
457 		return -EINVAL;
458 
459 	dev_dbg(dev, "%s secs=%d, mins=%d, "
460 		"hours=%d, mday=%d, enabled=%d, pending=%d\n",
461 		"alarm set", t->time.tm_sec, t->time.tm_min,
462 		t->time.tm_hour, t->time.tm_mday,
463 		t->enabled, t->pending);
464 
465 	/* read current status of both alarms and the chip */
466 	ret = regmap_bulk_read(ds1307->regmap, DS1339_REG_ALARM1_SECS, regs,
467 			       sizeof(regs));
468 	if (ret) {
469 		dev_err(dev, "%s error %d\n", "alarm write", ret);
470 		return ret;
471 	}
472 	control = regs[7];
473 	status = regs[8];
474 
475 	dev_dbg(dev, "%s: %4ph, %3ph, %02x %02x\n", "alarm set (old status)",
476 		&regs[0], &regs[4], control, status);
477 
478 	/* set ALARM1, using 24 hour and day-of-month modes */
479 	regs[0] = bin2bcd(t->time.tm_sec);
480 	regs[1] = bin2bcd(t->time.tm_min);
481 	regs[2] = bin2bcd(t->time.tm_hour);
482 	regs[3] = bin2bcd(t->time.tm_mday);
483 
484 	/* set ALARM2 to non-garbage */
485 	regs[4] = 0;
486 	regs[5] = 0;
487 	regs[6] = 0;
488 
489 	/* disable alarms */
490 	regs[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
491 	regs[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
492 
493 	ret = regmap_bulk_write(ds1307->regmap, DS1339_REG_ALARM1_SECS, regs,
494 				sizeof(regs));
495 	if (ret) {
496 		dev_err(dev, "can't set alarm time\n");
497 		return ret;
498 	}
499 
500 	/* optionally enable ALARM1 */
501 	if (t->enabled) {
502 		dev_dbg(dev, "alarm IRQ armed\n");
503 		regs[7] |= DS1337_BIT_A1IE;	/* only ALARM1 is used */
504 		regmap_write(ds1307->regmap, DS1337_REG_CONTROL, regs[7]);
505 	}
506 
507 	return 0;
508 }
509 
510 static int ds1307_alarm_irq_enable(struct device *dev, unsigned int enabled)
511 {
512 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
513 
514 	if (!test_bit(HAS_ALARM, &ds1307->flags))
515 		return -ENOTTY;
516 
517 	return regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
518 				  DS1337_BIT_A1IE,
519 				  enabled ? DS1337_BIT_A1IE : 0);
520 }
521 
522 static u8 do_trickle_setup_ds1339(struct ds1307 *ds1307, u32 ohms, bool diode)
523 {
524 	u8 setup = (diode) ? DS1307_TRICKLE_CHARGER_DIODE :
525 		DS1307_TRICKLE_CHARGER_NO_DIODE;
526 
527 	setup |= DS13XX_TRICKLE_CHARGER_MAGIC;
528 
529 	switch (ohms) {
530 	case 250:
531 		setup |= DS1307_TRICKLE_CHARGER_250_OHM;
532 		break;
533 	case 2000:
534 		setup |= DS1307_TRICKLE_CHARGER_2K_OHM;
535 		break;
536 	case 4000:
537 		setup |= DS1307_TRICKLE_CHARGER_4K_OHM;
538 		break;
539 	default:
540 		dev_warn(ds1307->dev,
541 			 "Unsupported ohm value %u in dt\n", ohms);
542 		return 0;
543 	}
544 	return setup;
545 }
546 
547 static u8 do_trickle_setup_rx8130(struct ds1307 *ds1307, u32 ohms, bool diode)
548 {
549 	/* make sure that the backup battery is enabled */
550 	u8 setup = RX8130_REG_CONTROL1_INIEN;
551 	if (diode)
552 		setup |= RX8130_REG_CONTROL1_CHGEN;
553 
554 	return setup;
555 }
556 
557 static irqreturn_t rx8130_irq(int irq, void *dev_id)
558 {
559 	struct ds1307           *ds1307 = dev_id;
560 	struct mutex            *lock = &ds1307->rtc->ops_lock;
561 	u8 ctl[3];
562 	int ret;
563 
564 	mutex_lock(lock);
565 
566 	/* Read control registers. */
567 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
568 			       sizeof(ctl));
569 	if (ret < 0)
570 		goto out;
571 	if (!(ctl[1] & RX8130_REG_FLAG_AF))
572 		goto out;
573 	ctl[1] &= ~RX8130_REG_FLAG_AF;
574 	ctl[2] &= ~RX8130_REG_CONTROL0_AIE;
575 
576 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
577 				sizeof(ctl));
578 	if (ret < 0)
579 		goto out;
580 
581 	rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
582 
583 out:
584 	mutex_unlock(lock);
585 
586 	return IRQ_HANDLED;
587 }
588 
589 static int rx8130_read_alarm(struct device *dev, struct rtc_wkalrm *t)
590 {
591 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
592 	u8 ald[3], ctl[3];
593 	int ret;
594 
595 	if (!test_bit(HAS_ALARM, &ds1307->flags))
596 		return -EINVAL;
597 
598 	/* Read alarm registers. */
599 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_ALARM_MIN, ald,
600 			       sizeof(ald));
601 	if (ret < 0)
602 		return ret;
603 
604 	/* Read control registers. */
605 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
606 			       sizeof(ctl));
607 	if (ret < 0)
608 		return ret;
609 
610 	t->enabled = !!(ctl[2] & RX8130_REG_CONTROL0_AIE);
611 	t->pending = !!(ctl[1] & RX8130_REG_FLAG_AF);
612 
613 	/* Report alarm 0 time assuming 24-hour and day-of-month modes. */
614 	t->time.tm_sec = -1;
615 	t->time.tm_min = bcd2bin(ald[0] & 0x7f);
616 	t->time.tm_hour = bcd2bin(ald[1] & 0x7f);
617 	t->time.tm_wday = -1;
618 	t->time.tm_mday = bcd2bin(ald[2] & 0x7f);
619 	t->time.tm_mon = -1;
620 	t->time.tm_year = -1;
621 	t->time.tm_yday = -1;
622 	t->time.tm_isdst = -1;
623 
624 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d enabled=%d\n",
625 		__func__, t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
626 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled);
627 
628 	return 0;
629 }
630 
631 static int rx8130_set_alarm(struct device *dev, struct rtc_wkalrm *t)
632 {
633 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
634 	u8 ald[3], ctl[3];
635 	int ret;
636 
637 	if (!test_bit(HAS_ALARM, &ds1307->flags))
638 		return -EINVAL;
639 
640 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
641 		"enabled=%d pending=%d\n", __func__,
642 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
643 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
644 		t->enabled, t->pending);
645 
646 	/* Read control registers. */
647 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
648 			       sizeof(ctl));
649 	if (ret < 0)
650 		return ret;
651 
652 	ctl[0] &= RX8130_REG_EXTENSION_WADA;
653 	ctl[1] &= ~RX8130_REG_FLAG_AF;
654 	ctl[2] &= ~RX8130_REG_CONTROL0_AIE;
655 
656 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
657 				sizeof(ctl));
658 	if (ret < 0)
659 		return ret;
660 
661 	/* Hardware alarm precision is 1 minute! */
662 	ald[0] = bin2bcd(t->time.tm_min);
663 	ald[1] = bin2bcd(t->time.tm_hour);
664 	ald[2] = bin2bcd(t->time.tm_mday);
665 
666 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_ALARM_MIN, ald,
667 				sizeof(ald));
668 	if (ret < 0)
669 		return ret;
670 
671 	if (!t->enabled)
672 		return 0;
673 
674 	ctl[2] |= RX8130_REG_CONTROL0_AIE;
675 
676 	return regmap_write(ds1307->regmap, RX8130_REG_CONTROL0, ctl[2]);
677 }
678 
679 static int rx8130_alarm_irq_enable(struct device *dev, unsigned int enabled)
680 {
681 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
682 	int ret, reg;
683 
684 	if (!test_bit(HAS_ALARM, &ds1307->flags))
685 		return -EINVAL;
686 
687 	ret = regmap_read(ds1307->regmap, RX8130_REG_CONTROL0, &reg);
688 	if (ret < 0)
689 		return ret;
690 
691 	if (enabled)
692 		reg |= RX8130_REG_CONTROL0_AIE;
693 	else
694 		reg &= ~RX8130_REG_CONTROL0_AIE;
695 
696 	return regmap_write(ds1307->regmap, RX8130_REG_CONTROL0, reg);
697 }
698 
699 static irqreturn_t mcp794xx_irq(int irq, void *dev_id)
700 {
701 	struct ds1307           *ds1307 = dev_id;
702 	struct mutex            *lock = &ds1307->rtc->ops_lock;
703 	int reg, ret;
704 
705 	mutex_lock(lock);
706 
707 	/* Check and clear alarm 0 interrupt flag. */
708 	ret = regmap_read(ds1307->regmap, MCP794XX_REG_ALARM0_CTRL, &reg);
709 	if (ret)
710 		goto out;
711 	if (!(reg & MCP794XX_BIT_ALMX_IF))
712 		goto out;
713 	reg &= ~MCP794XX_BIT_ALMX_IF;
714 	ret = regmap_write(ds1307->regmap, MCP794XX_REG_ALARM0_CTRL, reg);
715 	if (ret)
716 		goto out;
717 
718 	/* Disable alarm 0. */
719 	ret = regmap_update_bits(ds1307->regmap, MCP794XX_REG_CONTROL,
720 				 MCP794XX_BIT_ALM0_EN, 0);
721 	if (ret)
722 		goto out;
723 
724 	rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
725 
726 out:
727 	mutex_unlock(lock);
728 
729 	return IRQ_HANDLED;
730 }
731 
732 static int mcp794xx_read_alarm(struct device *dev, struct rtc_wkalrm *t)
733 {
734 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
735 	u8 regs[10];
736 	int ret;
737 
738 	if (!test_bit(HAS_ALARM, &ds1307->flags))
739 		return -EINVAL;
740 
741 	/* Read control and alarm 0 registers. */
742 	ret = regmap_bulk_read(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
743 			       sizeof(regs));
744 	if (ret)
745 		return ret;
746 
747 	t->enabled = !!(regs[0] & MCP794XX_BIT_ALM0_EN);
748 
749 	/* Report alarm 0 time assuming 24-hour and day-of-month modes. */
750 	t->time.tm_sec = bcd2bin(regs[3] & 0x7f);
751 	t->time.tm_min = bcd2bin(regs[4] & 0x7f);
752 	t->time.tm_hour = bcd2bin(regs[5] & 0x3f);
753 	t->time.tm_wday = bcd2bin(regs[6] & 0x7) - 1;
754 	t->time.tm_mday = bcd2bin(regs[7] & 0x3f);
755 	t->time.tm_mon = bcd2bin(regs[8] & 0x1f) - 1;
756 	t->time.tm_year = -1;
757 	t->time.tm_yday = -1;
758 	t->time.tm_isdst = -1;
759 
760 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
761 		"enabled=%d polarity=%d irq=%d match=%lu\n", __func__,
762 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
763 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled,
764 		!!(regs[6] & MCP794XX_BIT_ALMX_POL),
765 		!!(regs[6] & MCP794XX_BIT_ALMX_IF),
766 		(regs[6] & MCP794XX_MSK_ALMX_MATCH) >> 4);
767 
768 	return 0;
769 }
770 
771 /*
772  * We may have a random RTC weekday, therefore calculate alarm weekday based
773  * on current weekday we read from the RTC timekeeping regs
774  */
775 static int mcp794xx_alm_weekday(struct device *dev, struct rtc_time *tm_alarm)
776 {
777 	struct rtc_time tm_now;
778 	int days_now, days_alarm, ret;
779 
780 	ret = ds1307_get_time(dev, &tm_now);
781 	if (ret)
782 		return ret;
783 
784 	days_now = div_s64(rtc_tm_to_time64(&tm_now), 24 * 60 * 60);
785 	days_alarm = div_s64(rtc_tm_to_time64(tm_alarm), 24 * 60 * 60);
786 
787 	return (tm_now.tm_wday + days_alarm - days_now) % 7 + 1;
788 }
789 
790 static int mcp794xx_set_alarm(struct device *dev, struct rtc_wkalrm *t)
791 {
792 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
793 	unsigned char regs[10];
794 	int wday, ret;
795 
796 	if (!test_bit(HAS_ALARM, &ds1307->flags))
797 		return -EINVAL;
798 
799 	wday = mcp794xx_alm_weekday(dev, &t->time);
800 	if (wday < 0)
801 		return wday;
802 
803 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
804 		"enabled=%d pending=%d\n", __func__,
805 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
806 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
807 		t->enabled, t->pending);
808 
809 	/* Read control and alarm 0 registers. */
810 	ret = regmap_bulk_read(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
811 			       sizeof(regs));
812 	if (ret)
813 		return ret;
814 
815 	/* Set alarm 0, using 24-hour and day-of-month modes. */
816 	regs[3] = bin2bcd(t->time.tm_sec);
817 	regs[4] = bin2bcd(t->time.tm_min);
818 	regs[5] = bin2bcd(t->time.tm_hour);
819 	regs[6] = wday;
820 	regs[7] = bin2bcd(t->time.tm_mday);
821 	regs[8] = bin2bcd(t->time.tm_mon + 1);
822 
823 	/* Clear the alarm 0 interrupt flag. */
824 	regs[6] &= ~MCP794XX_BIT_ALMX_IF;
825 	/* Set alarm match: second, minute, hour, day, date, month. */
826 	regs[6] |= MCP794XX_MSK_ALMX_MATCH;
827 	/* Disable interrupt. We will not enable until completely programmed */
828 	regs[0] &= ~MCP794XX_BIT_ALM0_EN;
829 
830 	ret = regmap_bulk_write(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
831 				sizeof(regs));
832 	if (ret)
833 		return ret;
834 
835 	if (!t->enabled)
836 		return 0;
837 	regs[0] |= MCP794XX_BIT_ALM0_EN;
838 	return regmap_write(ds1307->regmap, MCP794XX_REG_CONTROL, regs[0]);
839 }
840 
841 static int mcp794xx_alarm_irq_enable(struct device *dev, unsigned int enabled)
842 {
843 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
844 
845 	if (!test_bit(HAS_ALARM, &ds1307->flags))
846 		return -EINVAL;
847 
848 	return regmap_update_bits(ds1307->regmap, MCP794XX_REG_CONTROL,
849 				  MCP794XX_BIT_ALM0_EN,
850 				  enabled ? MCP794XX_BIT_ALM0_EN : 0);
851 }
852 
853 static int m41txx_rtc_read_offset(struct device *dev, long *offset)
854 {
855 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
856 	unsigned int ctrl_reg;
857 	u8 val;
858 
859 	regmap_read(ds1307->regmap, M41TXX_REG_CONTROL, &ctrl_reg);
860 
861 	val = ctrl_reg & M41TXX_M_CALIBRATION;
862 
863 	/* check if positive */
864 	if (ctrl_reg & M41TXX_BIT_CALIB_SIGN)
865 		*offset = (val * M41TXX_POS_OFFSET_STEP_PPB);
866 	else
867 		*offset = -(val * M41TXX_NEG_OFFSET_STEP_PPB);
868 
869 	return 0;
870 }
871 
872 static int m41txx_rtc_set_offset(struct device *dev, long offset)
873 {
874 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
875 	unsigned int ctrl_reg;
876 
877 	if ((offset < M41TXX_MIN_OFFSET) || (offset > M41TXX_MAX_OFFSET))
878 		return -ERANGE;
879 
880 	if (offset >= 0) {
881 		ctrl_reg = DIV_ROUND_CLOSEST(offset,
882 					     M41TXX_POS_OFFSET_STEP_PPB);
883 		ctrl_reg |= M41TXX_BIT_CALIB_SIGN;
884 	} else {
885 		ctrl_reg = DIV_ROUND_CLOSEST(abs(offset),
886 					     M41TXX_NEG_OFFSET_STEP_PPB);
887 	}
888 
889 	return regmap_update_bits(ds1307->regmap, M41TXX_REG_CONTROL,
890 				  M41TXX_M_CALIBRATION | M41TXX_BIT_CALIB_SIGN,
891 				  ctrl_reg);
892 }
893 
894 #ifdef CONFIG_WATCHDOG_CORE
895 static int ds1388_wdt_start(struct watchdog_device *wdt_dev)
896 {
897 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
898 	u8 regs[2];
899 	int ret;
900 
901 	ret = regmap_update_bits(ds1307->regmap, DS1388_REG_FLAG,
902 				 DS1388_BIT_WF, 0);
903 	if (ret)
904 		return ret;
905 
906 	ret = regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
907 				 DS1388_BIT_WDE | DS1388_BIT_RST, 0);
908 	if (ret)
909 		return ret;
910 
911 	/*
912 	 * watchdog timeouts are measured in seconds. So ignore hundredths of
913 	 * seconds field.
914 	 */
915 	regs[0] = 0;
916 	regs[1] = bin2bcd(wdt_dev->timeout);
917 
918 	ret = regmap_bulk_write(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
919 				sizeof(regs));
920 	if (ret)
921 		return ret;
922 
923 	return regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
924 				  DS1388_BIT_WDE | DS1388_BIT_RST,
925 				  DS1388_BIT_WDE | DS1388_BIT_RST);
926 }
927 
928 static int ds1388_wdt_stop(struct watchdog_device *wdt_dev)
929 {
930 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
931 
932 	return regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
933 				  DS1388_BIT_WDE | DS1388_BIT_RST, 0);
934 }
935 
936 static int ds1388_wdt_ping(struct watchdog_device *wdt_dev)
937 {
938 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
939 	u8 regs[2];
940 
941 	return regmap_bulk_read(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
942 				sizeof(regs));
943 }
944 
945 static int ds1388_wdt_set_timeout(struct watchdog_device *wdt_dev,
946 				  unsigned int val)
947 {
948 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
949 	u8 regs[2];
950 
951 	wdt_dev->timeout = val;
952 	regs[0] = 0;
953 	regs[1] = bin2bcd(wdt_dev->timeout);
954 
955 	return regmap_bulk_write(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
956 				 sizeof(regs));
957 }
958 #endif
959 
960 static const struct rtc_class_ops rx8130_rtc_ops = {
961 	.read_time      = ds1307_get_time,
962 	.set_time       = ds1307_set_time,
963 	.read_alarm     = rx8130_read_alarm,
964 	.set_alarm      = rx8130_set_alarm,
965 	.alarm_irq_enable = rx8130_alarm_irq_enable,
966 };
967 
968 static const struct rtc_class_ops mcp794xx_rtc_ops = {
969 	.read_time      = ds1307_get_time,
970 	.set_time       = ds1307_set_time,
971 	.read_alarm     = mcp794xx_read_alarm,
972 	.set_alarm      = mcp794xx_set_alarm,
973 	.alarm_irq_enable = mcp794xx_alarm_irq_enable,
974 };
975 
976 static const struct rtc_class_ops m41txx_rtc_ops = {
977 	.read_time      = ds1307_get_time,
978 	.set_time       = ds1307_set_time,
979 	.read_alarm	= ds1337_read_alarm,
980 	.set_alarm	= ds1337_set_alarm,
981 	.alarm_irq_enable = ds1307_alarm_irq_enable,
982 	.read_offset	= m41txx_rtc_read_offset,
983 	.set_offset	= m41txx_rtc_set_offset,
984 };
985 
986 static const struct chip_desc chips[last_ds_type] = {
987 	[ds_1307] = {
988 		.nvram_offset	= 8,
989 		.nvram_size	= 56,
990 	},
991 	[ds_1308] = {
992 		.nvram_offset	= 8,
993 		.nvram_size	= 56,
994 	},
995 	[ds_1337] = {
996 		.alarm		= 1,
997 		.century_reg	= DS1307_REG_MONTH,
998 		.century_bit	= DS1337_BIT_CENTURY,
999 	},
1000 	[ds_1338] = {
1001 		.nvram_offset	= 8,
1002 		.nvram_size	= 56,
1003 	},
1004 	[ds_1339] = {
1005 		.alarm		= 1,
1006 		.century_reg	= DS1307_REG_MONTH,
1007 		.century_bit	= DS1337_BIT_CENTURY,
1008 		.bbsqi_bit	= DS1339_BIT_BBSQI,
1009 		.trickle_charger_reg = 0x10,
1010 		.do_trickle_setup = &do_trickle_setup_ds1339,
1011 		.requires_trickle_resistor = true,
1012 		.charge_default = true,
1013 	},
1014 	[ds_1340] = {
1015 		.century_reg	= DS1307_REG_HOUR,
1016 		.century_enable_bit = DS1340_BIT_CENTURY_EN,
1017 		.century_bit	= DS1340_BIT_CENTURY,
1018 		.do_trickle_setup = &do_trickle_setup_ds1339,
1019 		.trickle_charger_reg = 0x08,
1020 		.requires_trickle_resistor = true,
1021 		.charge_default = true,
1022 	},
1023 	[ds_1341] = {
1024 		.century_reg	= DS1307_REG_MONTH,
1025 		.century_bit	= DS1337_BIT_CENTURY,
1026 	},
1027 	[ds_1388] = {
1028 		.offset		= 1,
1029 		.trickle_charger_reg = 0x0a,
1030 	},
1031 	[ds_3231] = {
1032 		.alarm		= 1,
1033 		.century_reg	= DS1307_REG_MONTH,
1034 		.century_bit	= DS1337_BIT_CENTURY,
1035 		.bbsqi_bit	= DS3231_BIT_BBSQW,
1036 	},
1037 	[rx_8130] = {
1038 		.alarm		= 1,
1039 		/* this is battery backed SRAM */
1040 		.nvram_offset	= 0x20,
1041 		.nvram_size	= 4,	/* 32bit (4 word x 8 bit) */
1042 		.offset		= 0x10,
1043 		.irq_handler = rx8130_irq,
1044 		.rtc_ops = &rx8130_rtc_ops,
1045 		.trickle_charger_reg = RX8130_REG_CONTROL1,
1046 		.do_trickle_setup = &do_trickle_setup_rx8130,
1047 	},
1048 	[m41t0] = {
1049 		.rtc_ops	= &m41txx_rtc_ops,
1050 	},
1051 	[m41t00] = {
1052 		.rtc_ops	= &m41txx_rtc_ops,
1053 	},
1054 	[m41t11] = {
1055 		/* this is battery backed SRAM */
1056 		.nvram_offset	= 8,
1057 		.nvram_size	= 56,
1058 		.rtc_ops	= &m41txx_rtc_ops,
1059 	},
1060 	[mcp794xx] = {
1061 		.alarm		= 1,
1062 		/* this is battery backed SRAM */
1063 		.nvram_offset	= 0x20,
1064 		.nvram_size	= 0x40,
1065 		.irq_handler = mcp794xx_irq,
1066 		.rtc_ops = &mcp794xx_rtc_ops,
1067 	},
1068 };
1069 
1070 static const struct i2c_device_id ds1307_id[] = {
1071 	{ "ds1307", ds_1307 },
1072 	{ "ds1308", ds_1308 },
1073 	{ "ds1337", ds_1337 },
1074 	{ "ds1338", ds_1338 },
1075 	{ "ds1339", ds_1339 },
1076 	{ "ds1388", ds_1388 },
1077 	{ "ds1340", ds_1340 },
1078 	{ "ds1341", ds_1341 },
1079 	{ "ds3231", ds_3231 },
1080 	{ "m41t0", m41t0 },
1081 	{ "m41t00", m41t00 },
1082 	{ "m41t11", m41t11 },
1083 	{ "mcp7940x", mcp794xx },
1084 	{ "mcp7941x", mcp794xx },
1085 	{ "pt7c4338", ds_1307 },
1086 	{ "rx8025", rx_8025 },
1087 	{ "isl12057", ds_1337 },
1088 	{ "rx8130", rx_8130 },
1089 	{ }
1090 };
1091 MODULE_DEVICE_TABLE(i2c, ds1307_id);
1092 
1093 #ifdef CONFIG_OF
1094 static const struct of_device_id ds1307_of_match[] = {
1095 	{
1096 		.compatible = "dallas,ds1307",
1097 		.data = (void *)ds_1307
1098 	},
1099 	{
1100 		.compatible = "dallas,ds1308",
1101 		.data = (void *)ds_1308
1102 	},
1103 	{
1104 		.compatible = "dallas,ds1337",
1105 		.data = (void *)ds_1337
1106 	},
1107 	{
1108 		.compatible = "dallas,ds1338",
1109 		.data = (void *)ds_1338
1110 	},
1111 	{
1112 		.compatible = "dallas,ds1339",
1113 		.data = (void *)ds_1339
1114 	},
1115 	{
1116 		.compatible = "dallas,ds1388",
1117 		.data = (void *)ds_1388
1118 	},
1119 	{
1120 		.compatible = "dallas,ds1340",
1121 		.data = (void *)ds_1340
1122 	},
1123 	{
1124 		.compatible = "dallas,ds1341",
1125 		.data = (void *)ds_1341
1126 	},
1127 	{
1128 		.compatible = "maxim,ds3231",
1129 		.data = (void *)ds_3231
1130 	},
1131 	{
1132 		.compatible = "st,m41t0",
1133 		.data = (void *)m41t0
1134 	},
1135 	{
1136 		.compatible = "st,m41t00",
1137 		.data = (void *)m41t00
1138 	},
1139 	{
1140 		.compatible = "st,m41t11",
1141 		.data = (void *)m41t11
1142 	},
1143 	{
1144 		.compatible = "microchip,mcp7940x",
1145 		.data = (void *)mcp794xx
1146 	},
1147 	{
1148 		.compatible = "microchip,mcp7941x",
1149 		.data = (void *)mcp794xx
1150 	},
1151 	{
1152 		.compatible = "pericom,pt7c4338",
1153 		.data = (void *)ds_1307
1154 	},
1155 	{
1156 		.compatible = "epson,rx8025",
1157 		.data = (void *)rx_8025
1158 	},
1159 	{
1160 		.compatible = "isil,isl12057",
1161 		.data = (void *)ds_1337
1162 	},
1163 	{
1164 		.compatible = "epson,rx8130",
1165 		.data = (void *)rx_8130
1166 	},
1167 	{ }
1168 };
1169 MODULE_DEVICE_TABLE(of, ds1307_of_match);
1170 #endif
1171 
1172 #ifdef CONFIG_ACPI
1173 static const struct acpi_device_id ds1307_acpi_ids[] = {
1174 	{ .id = "DS1307", .driver_data = ds_1307 },
1175 	{ .id = "DS1308", .driver_data = ds_1308 },
1176 	{ .id = "DS1337", .driver_data = ds_1337 },
1177 	{ .id = "DS1338", .driver_data = ds_1338 },
1178 	{ .id = "DS1339", .driver_data = ds_1339 },
1179 	{ .id = "DS1388", .driver_data = ds_1388 },
1180 	{ .id = "DS1340", .driver_data = ds_1340 },
1181 	{ .id = "DS1341", .driver_data = ds_1341 },
1182 	{ .id = "DS3231", .driver_data = ds_3231 },
1183 	{ .id = "M41T0", .driver_data = m41t0 },
1184 	{ .id = "M41T00", .driver_data = m41t00 },
1185 	{ .id = "M41T11", .driver_data = m41t11 },
1186 	{ .id = "MCP7940X", .driver_data = mcp794xx },
1187 	{ .id = "MCP7941X", .driver_data = mcp794xx },
1188 	{ .id = "PT7C4338", .driver_data = ds_1307 },
1189 	{ .id = "RX8025", .driver_data = rx_8025 },
1190 	{ .id = "ISL12057", .driver_data = ds_1337 },
1191 	{ .id = "RX8130", .driver_data = rx_8130 },
1192 	{ }
1193 };
1194 MODULE_DEVICE_TABLE(acpi, ds1307_acpi_ids);
1195 #endif
1196 
1197 /*
1198  * The ds1337 and ds1339 both have two alarms, but we only use the first
1199  * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
1200  * signal; ds1339 chips have only one alarm signal.
1201  */
1202 static irqreturn_t ds1307_irq(int irq, void *dev_id)
1203 {
1204 	struct ds1307		*ds1307 = dev_id;
1205 	struct mutex		*lock = &ds1307->rtc->ops_lock;
1206 	int			stat, ret;
1207 
1208 	mutex_lock(lock);
1209 	ret = regmap_read(ds1307->regmap, DS1337_REG_STATUS, &stat);
1210 	if (ret)
1211 		goto out;
1212 
1213 	if (stat & DS1337_BIT_A1I) {
1214 		stat &= ~DS1337_BIT_A1I;
1215 		regmap_write(ds1307->regmap, DS1337_REG_STATUS, stat);
1216 
1217 		ret = regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
1218 					 DS1337_BIT_A1IE, 0);
1219 		if (ret)
1220 			goto out;
1221 
1222 		rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
1223 	}
1224 
1225 out:
1226 	mutex_unlock(lock);
1227 
1228 	return IRQ_HANDLED;
1229 }
1230 
1231 /*----------------------------------------------------------------------*/
1232 
1233 static const struct rtc_class_ops ds13xx_rtc_ops = {
1234 	.read_time	= ds1307_get_time,
1235 	.set_time	= ds1307_set_time,
1236 	.read_alarm	= ds1337_read_alarm,
1237 	.set_alarm	= ds1337_set_alarm,
1238 	.alarm_irq_enable = ds1307_alarm_irq_enable,
1239 };
1240 
1241 static ssize_t frequency_test_store(struct device *dev,
1242 				    struct device_attribute *attr,
1243 				    const char *buf, size_t count)
1244 {
1245 	struct ds1307 *ds1307 = dev_get_drvdata(dev->parent);
1246 	bool freq_test_en;
1247 	int ret;
1248 
1249 	ret = kstrtobool(buf, &freq_test_en);
1250 	if (ret) {
1251 		dev_err(dev, "Failed to store RTC Frequency Test attribute\n");
1252 		return ret;
1253 	}
1254 
1255 	regmap_update_bits(ds1307->regmap, M41TXX_REG_CONTROL, M41TXX_BIT_FT,
1256 			   freq_test_en ? M41TXX_BIT_FT : 0);
1257 
1258 	return count;
1259 }
1260 
1261 static ssize_t frequency_test_show(struct device *dev,
1262 				   struct device_attribute *attr,
1263 				   char *buf)
1264 {
1265 	struct ds1307 *ds1307 = dev_get_drvdata(dev->parent);
1266 	unsigned int ctrl_reg;
1267 
1268 	regmap_read(ds1307->regmap, M41TXX_REG_CONTROL, &ctrl_reg);
1269 
1270 	return scnprintf(buf, PAGE_SIZE, (ctrl_reg & M41TXX_BIT_FT) ? "on\n" :
1271 			"off\n");
1272 }
1273 
1274 static DEVICE_ATTR_RW(frequency_test);
1275 
1276 static struct attribute *rtc_freq_test_attrs[] = {
1277 	&dev_attr_frequency_test.attr,
1278 	NULL,
1279 };
1280 
1281 static const struct attribute_group rtc_freq_test_attr_group = {
1282 	.attrs		= rtc_freq_test_attrs,
1283 };
1284 
1285 static int ds1307_add_frequency_test(struct ds1307 *ds1307)
1286 {
1287 	int err;
1288 
1289 	switch (ds1307->type) {
1290 	case m41t0:
1291 	case m41t00:
1292 	case m41t11:
1293 		err = rtc_add_group(ds1307->rtc, &rtc_freq_test_attr_group);
1294 		if (err)
1295 			return err;
1296 		break;
1297 	default:
1298 		break;
1299 	}
1300 
1301 	return 0;
1302 }
1303 
1304 /*----------------------------------------------------------------------*/
1305 
1306 static int ds1307_nvram_read(void *priv, unsigned int offset, void *val,
1307 			     size_t bytes)
1308 {
1309 	struct ds1307 *ds1307 = priv;
1310 	const struct chip_desc *chip = &chips[ds1307->type];
1311 
1312 	return regmap_bulk_read(ds1307->regmap, chip->nvram_offset + offset,
1313 				val, bytes);
1314 }
1315 
1316 static int ds1307_nvram_write(void *priv, unsigned int offset, void *val,
1317 			      size_t bytes)
1318 {
1319 	struct ds1307 *ds1307 = priv;
1320 	const struct chip_desc *chip = &chips[ds1307->type];
1321 
1322 	return regmap_bulk_write(ds1307->regmap, chip->nvram_offset + offset,
1323 				 val, bytes);
1324 }
1325 
1326 /*----------------------------------------------------------------------*/
1327 
1328 static u8 ds1307_trickle_init(struct ds1307 *ds1307,
1329 			      const struct chip_desc *chip)
1330 {
1331 	u32 ohms, chargeable;
1332 	bool diode = chip->charge_default;
1333 
1334 	if (!chip->do_trickle_setup)
1335 		return 0;
1336 
1337 	if (device_property_read_u32(ds1307->dev, "trickle-resistor-ohms",
1338 				     &ohms) && chip->requires_trickle_resistor)
1339 		return 0;
1340 
1341 	/* aux-voltage-chargeable takes precedence over the deprecated
1342 	 * trickle-diode-disable
1343 	 */
1344 	if (!device_property_read_u32(ds1307->dev, "aux-voltage-chargeable",
1345 				     &chargeable)) {
1346 		switch (chargeable) {
1347 		case 0:
1348 			diode = false;
1349 			break;
1350 		case 1:
1351 			diode = true;
1352 			break;
1353 		default:
1354 			dev_warn(ds1307->dev,
1355 				 "unsupported aux-voltage-chargeable value\n");
1356 			break;
1357 		}
1358 	} else if (device_property_read_bool(ds1307->dev,
1359 					     "trickle-diode-disable")) {
1360 		diode = false;
1361 	}
1362 
1363 	return chip->do_trickle_setup(ds1307, ohms, diode);
1364 }
1365 
1366 /*----------------------------------------------------------------------*/
1367 
1368 #if IS_REACHABLE(CONFIG_HWMON)
1369 
1370 /*
1371  * Temperature sensor support for ds3231 devices.
1372  */
1373 
1374 #define DS3231_REG_TEMPERATURE	0x11
1375 
1376 /*
1377  * A user-initiated temperature conversion is not started by this function,
1378  * so the temperature is updated once every 64 seconds.
1379  */
1380 static int ds3231_hwmon_read_temp(struct device *dev, s32 *mC)
1381 {
1382 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
1383 	u8 temp_buf[2];
1384 	s16 temp;
1385 	int ret;
1386 
1387 	ret = regmap_bulk_read(ds1307->regmap, DS3231_REG_TEMPERATURE,
1388 			       temp_buf, sizeof(temp_buf));
1389 	if (ret)
1390 		return ret;
1391 	/*
1392 	 * Temperature is represented as a 10-bit code with a resolution of
1393 	 * 0.25 degree celsius and encoded in two's complement format.
1394 	 */
1395 	temp = (temp_buf[0] << 8) | temp_buf[1];
1396 	temp >>= 6;
1397 	*mC = temp * 250;
1398 
1399 	return 0;
1400 }
1401 
1402 static ssize_t ds3231_hwmon_show_temp(struct device *dev,
1403 				      struct device_attribute *attr, char *buf)
1404 {
1405 	int ret;
1406 	s32 temp;
1407 
1408 	ret = ds3231_hwmon_read_temp(dev, &temp);
1409 	if (ret)
1410 		return ret;
1411 
1412 	return sprintf(buf, "%d\n", temp);
1413 }
1414 static SENSOR_DEVICE_ATTR(temp1_input, 0444, ds3231_hwmon_show_temp,
1415 			  NULL, 0);
1416 
1417 static struct attribute *ds3231_hwmon_attrs[] = {
1418 	&sensor_dev_attr_temp1_input.dev_attr.attr,
1419 	NULL,
1420 };
1421 ATTRIBUTE_GROUPS(ds3231_hwmon);
1422 
1423 static void ds1307_hwmon_register(struct ds1307 *ds1307)
1424 {
1425 	struct device *dev;
1426 
1427 	if (ds1307->type != ds_3231)
1428 		return;
1429 
1430 	dev = devm_hwmon_device_register_with_groups(ds1307->dev, ds1307->name,
1431 						     ds1307,
1432 						     ds3231_hwmon_groups);
1433 	if (IS_ERR(dev)) {
1434 		dev_warn(ds1307->dev, "unable to register hwmon device %ld\n",
1435 			 PTR_ERR(dev));
1436 	}
1437 }
1438 
1439 #else
1440 
1441 static void ds1307_hwmon_register(struct ds1307 *ds1307)
1442 {
1443 }
1444 
1445 #endif /* CONFIG_RTC_DRV_DS1307_HWMON */
1446 
1447 /*----------------------------------------------------------------------*/
1448 
1449 /*
1450  * Square-wave output support for DS3231
1451  * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS3231.pdf
1452  */
1453 #ifdef CONFIG_COMMON_CLK
1454 
1455 enum {
1456 	DS3231_CLK_SQW = 0,
1457 	DS3231_CLK_32KHZ,
1458 };
1459 
1460 #define clk_sqw_to_ds1307(clk)	\
1461 	container_of(clk, struct ds1307, clks[DS3231_CLK_SQW])
1462 #define clk_32khz_to_ds1307(clk)	\
1463 	container_of(clk, struct ds1307, clks[DS3231_CLK_32KHZ])
1464 
1465 static int ds3231_clk_sqw_rates[] = {
1466 	1,
1467 	1024,
1468 	4096,
1469 	8192,
1470 };
1471 
1472 static int ds1337_write_control(struct ds1307 *ds1307, u8 mask, u8 value)
1473 {
1474 	struct mutex *lock = &ds1307->rtc->ops_lock;
1475 	int ret;
1476 
1477 	mutex_lock(lock);
1478 	ret = regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
1479 				 mask, value);
1480 	mutex_unlock(lock);
1481 
1482 	return ret;
1483 }
1484 
1485 static unsigned long ds3231_clk_sqw_recalc_rate(struct clk_hw *hw,
1486 						unsigned long parent_rate)
1487 {
1488 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1489 	int control, ret;
1490 	int rate_sel = 0;
1491 
1492 	ret = regmap_read(ds1307->regmap, DS1337_REG_CONTROL, &control);
1493 	if (ret)
1494 		return ret;
1495 	if (control & DS1337_BIT_RS1)
1496 		rate_sel += 1;
1497 	if (control & DS1337_BIT_RS2)
1498 		rate_sel += 2;
1499 
1500 	return ds3231_clk_sqw_rates[rate_sel];
1501 }
1502 
1503 static long ds3231_clk_sqw_round_rate(struct clk_hw *hw, unsigned long rate,
1504 				      unsigned long *prate)
1505 {
1506 	int i;
1507 
1508 	for (i = ARRAY_SIZE(ds3231_clk_sqw_rates) - 1; i >= 0; i--) {
1509 		if (ds3231_clk_sqw_rates[i] <= rate)
1510 			return ds3231_clk_sqw_rates[i];
1511 	}
1512 
1513 	return 0;
1514 }
1515 
1516 static int ds3231_clk_sqw_set_rate(struct clk_hw *hw, unsigned long rate,
1517 				   unsigned long parent_rate)
1518 {
1519 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1520 	int control = 0;
1521 	int rate_sel;
1522 
1523 	for (rate_sel = 0; rate_sel < ARRAY_SIZE(ds3231_clk_sqw_rates);
1524 			rate_sel++) {
1525 		if (ds3231_clk_sqw_rates[rate_sel] == rate)
1526 			break;
1527 	}
1528 
1529 	if (rate_sel == ARRAY_SIZE(ds3231_clk_sqw_rates))
1530 		return -EINVAL;
1531 
1532 	if (rate_sel & 1)
1533 		control |= DS1337_BIT_RS1;
1534 	if (rate_sel & 2)
1535 		control |= DS1337_BIT_RS2;
1536 
1537 	return ds1337_write_control(ds1307, DS1337_BIT_RS1 | DS1337_BIT_RS2,
1538 				control);
1539 }
1540 
1541 static int ds3231_clk_sqw_prepare(struct clk_hw *hw)
1542 {
1543 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1544 
1545 	return ds1337_write_control(ds1307, DS1337_BIT_INTCN, 0);
1546 }
1547 
1548 static void ds3231_clk_sqw_unprepare(struct clk_hw *hw)
1549 {
1550 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1551 
1552 	ds1337_write_control(ds1307, DS1337_BIT_INTCN, DS1337_BIT_INTCN);
1553 }
1554 
1555 static int ds3231_clk_sqw_is_prepared(struct clk_hw *hw)
1556 {
1557 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1558 	int control, ret;
1559 
1560 	ret = regmap_read(ds1307->regmap, DS1337_REG_CONTROL, &control);
1561 	if (ret)
1562 		return ret;
1563 
1564 	return !(control & DS1337_BIT_INTCN);
1565 }
1566 
1567 static const struct clk_ops ds3231_clk_sqw_ops = {
1568 	.prepare = ds3231_clk_sqw_prepare,
1569 	.unprepare = ds3231_clk_sqw_unprepare,
1570 	.is_prepared = ds3231_clk_sqw_is_prepared,
1571 	.recalc_rate = ds3231_clk_sqw_recalc_rate,
1572 	.round_rate = ds3231_clk_sqw_round_rate,
1573 	.set_rate = ds3231_clk_sqw_set_rate,
1574 };
1575 
1576 static unsigned long ds3231_clk_32khz_recalc_rate(struct clk_hw *hw,
1577 						  unsigned long parent_rate)
1578 {
1579 	return 32768;
1580 }
1581 
1582 static int ds3231_clk_32khz_control(struct ds1307 *ds1307, bool enable)
1583 {
1584 	struct mutex *lock = &ds1307->rtc->ops_lock;
1585 	int ret;
1586 
1587 	mutex_lock(lock);
1588 	ret = regmap_update_bits(ds1307->regmap, DS1337_REG_STATUS,
1589 				 DS3231_BIT_EN32KHZ,
1590 				 enable ? DS3231_BIT_EN32KHZ : 0);
1591 	mutex_unlock(lock);
1592 
1593 	return ret;
1594 }
1595 
1596 static int ds3231_clk_32khz_prepare(struct clk_hw *hw)
1597 {
1598 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1599 
1600 	return ds3231_clk_32khz_control(ds1307, true);
1601 }
1602 
1603 static void ds3231_clk_32khz_unprepare(struct clk_hw *hw)
1604 {
1605 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1606 
1607 	ds3231_clk_32khz_control(ds1307, false);
1608 }
1609 
1610 static int ds3231_clk_32khz_is_prepared(struct clk_hw *hw)
1611 {
1612 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1613 	int status, ret;
1614 
1615 	ret = regmap_read(ds1307->regmap, DS1337_REG_STATUS, &status);
1616 	if (ret)
1617 		return ret;
1618 
1619 	return !!(status & DS3231_BIT_EN32KHZ);
1620 }
1621 
1622 static const struct clk_ops ds3231_clk_32khz_ops = {
1623 	.prepare = ds3231_clk_32khz_prepare,
1624 	.unprepare = ds3231_clk_32khz_unprepare,
1625 	.is_prepared = ds3231_clk_32khz_is_prepared,
1626 	.recalc_rate = ds3231_clk_32khz_recalc_rate,
1627 };
1628 
1629 static struct clk_init_data ds3231_clks_init[] = {
1630 	[DS3231_CLK_SQW] = {
1631 		.name = "ds3231_clk_sqw",
1632 		.ops = &ds3231_clk_sqw_ops,
1633 	},
1634 	[DS3231_CLK_32KHZ] = {
1635 		.name = "ds3231_clk_32khz",
1636 		.ops = &ds3231_clk_32khz_ops,
1637 	},
1638 };
1639 
1640 static int ds3231_clks_register(struct ds1307 *ds1307)
1641 {
1642 	struct device_node *node = ds1307->dev->of_node;
1643 	struct clk_onecell_data	*onecell;
1644 	int i;
1645 
1646 	onecell = devm_kzalloc(ds1307->dev, sizeof(*onecell), GFP_KERNEL);
1647 	if (!onecell)
1648 		return -ENOMEM;
1649 
1650 	onecell->clk_num = ARRAY_SIZE(ds3231_clks_init);
1651 	onecell->clks = devm_kcalloc(ds1307->dev, onecell->clk_num,
1652 				     sizeof(onecell->clks[0]), GFP_KERNEL);
1653 	if (!onecell->clks)
1654 		return -ENOMEM;
1655 
1656 	for (i = 0; i < ARRAY_SIZE(ds3231_clks_init); i++) {
1657 		struct clk_init_data init = ds3231_clks_init[i];
1658 
1659 		/*
1660 		 * Interrupt signal due to alarm conditions and square-wave
1661 		 * output share same pin, so don't initialize both.
1662 		 */
1663 		if (i == DS3231_CLK_SQW && test_bit(HAS_ALARM, &ds1307->flags))
1664 			continue;
1665 
1666 		/* optional override of the clockname */
1667 		of_property_read_string_index(node, "clock-output-names", i,
1668 					      &init.name);
1669 		ds1307->clks[i].init = &init;
1670 
1671 		onecell->clks[i] = devm_clk_register(ds1307->dev,
1672 						     &ds1307->clks[i]);
1673 		if (IS_ERR(onecell->clks[i]))
1674 			return PTR_ERR(onecell->clks[i]);
1675 	}
1676 
1677 	if (!node)
1678 		return 0;
1679 
1680 	of_clk_add_provider(node, of_clk_src_onecell_get, onecell);
1681 
1682 	return 0;
1683 }
1684 
1685 static void ds1307_clks_register(struct ds1307 *ds1307)
1686 {
1687 	int ret;
1688 
1689 	if (ds1307->type != ds_3231)
1690 		return;
1691 
1692 	ret = ds3231_clks_register(ds1307);
1693 	if (ret) {
1694 		dev_warn(ds1307->dev, "unable to register clock device %d\n",
1695 			 ret);
1696 	}
1697 }
1698 
1699 #else
1700 
1701 static void ds1307_clks_register(struct ds1307 *ds1307)
1702 {
1703 }
1704 
1705 #endif /* CONFIG_COMMON_CLK */
1706 
1707 #ifdef CONFIG_WATCHDOG_CORE
1708 static const struct watchdog_info ds1388_wdt_info = {
1709 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
1710 	.identity = "DS1388 watchdog",
1711 };
1712 
1713 static const struct watchdog_ops ds1388_wdt_ops = {
1714 	.owner = THIS_MODULE,
1715 	.start = ds1388_wdt_start,
1716 	.stop = ds1388_wdt_stop,
1717 	.ping = ds1388_wdt_ping,
1718 	.set_timeout = ds1388_wdt_set_timeout,
1719 
1720 };
1721 
1722 static void ds1307_wdt_register(struct ds1307 *ds1307)
1723 {
1724 	struct watchdog_device	*wdt;
1725 	int err;
1726 	int val;
1727 
1728 	if (ds1307->type != ds_1388)
1729 		return;
1730 
1731 	wdt = devm_kzalloc(ds1307->dev, sizeof(*wdt), GFP_KERNEL);
1732 	if (!wdt)
1733 		return;
1734 
1735 	err = regmap_read(ds1307->regmap, DS1388_REG_FLAG, &val);
1736 	if (!err && val & DS1388_BIT_WF)
1737 		wdt->bootstatus = WDIOF_CARDRESET;
1738 
1739 	wdt->info = &ds1388_wdt_info;
1740 	wdt->ops = &ds1388_wdt_ops;
1741 	wdt->timeout = 99;
1742 	wdt->max_timeout = 99;
1743 	wdt->min_timeout = 1;
1744 
1745 	watchdog_init_timeout(wdt, 0, ds1307->dev);
1746 	watchdog_set_drvdata(wdt, ds1307);
1747 	devm_watchdog_register_device(ds1307->dev, wdt);
1748 }
1749 #else
1750 static void ds1307_wdt_register(struct ds1307 *ds1307)
1751 {
1752 }
1753 #endif /* CONFIG_WATCHDOG_CORE */
1754 
1755 static const struct regmap_config regmap_config = {
1756 	.reg_bits = 8,
1757 	.val_bits = 8,
1758 };
1759 
1760 static int ds1307_probe(struct i2c_client *client,
1761 			const struct i2c_device_id *id)
1762 {
1763 	struct ds1307		*ds1307;
1764 	int			err = -ENODEV;
1765 	int			tmp;
1766 	const struct chip_desc	*chip;
1767 	bool			want_irq;
1768 	bool			ds1307_can_wakeup_device = false;
1769 	unsigned char		regs[8];
1770 	struct ds1307_platform_data *pdata = dev_get_platdata(&client->dev);
1771 	u8			trickle_charger_setup = 0;
1772 
1773 	ds1307 = devm_kzalloc(&client->dev, sizeof(struct ds1307), GFP_KERNEL);
1774 	if (!ds1307)
1775 		return -ENOMEM;
1776 
1777 	dev_set_drvdata(&client->dev, ds1307);
1778 	ds1307->dev = &client->dev;
1779 	ds1307->name = client->name;
1780 
1781 	ds1307->regmap = devm_regmap_init_i2c(client, &regmap_config);
1782 	if (IS_ERR(ds1307->regmap)) {
1783 		dev_err(ds1307->dev, "regmap allocation failed\n");
1784 		return PTR_ERR(ds1307->regmap);
1785 	}
1786 
1787 	i2c_set_clientdata(client, ds1307);
1788 
1789 	if (client->dev.of_node) {
1790 		ds1307->type = (enum ds_type)
1791 			of_device_get_match_data(&client->dev);
1792 		chip = &chips[ds1307->type];
1793 	} else if (id) {
1794 		chip = &chips[id->driver_data];
1795 		ds1307->type = id->driver_data;
1796 	} else {
1797 		const struct acpi_device_id *acpi_id;
1798 
1799 		acpi_id = acpi_match_device(ACPI_PTR(ds1307_acpi_ids),
1800 					    ds1307->dev);
1801 		if (!acpi_id)
1802 			return -ENODEV;
1803 		chip = &chips[acpi_id->driver_data];
1804 		ds1307->type = acpi_id->driver_data;
1805 	}
1806 
1807 	want_irq = client->irq > 0 && chip->alarm;
1808 
1809 	if (!pdata)
1810 		trickle_charger_setup = ds1307_trickle_init(ds1307, chip);
1811 	else if (pdata->trickle_charger_setup)
1812 		trickle_charger_setup = pdata->trickle_charger_setup;
1813 
1814 	if (trickle_charger_setup && chip->trickle_charger_reg) {
1815 		dev_dbg(ds1307->dev,
1816 			"writing trickle charger info 0x%x to 0x%x\n",
1817 			trickle_charger_setup, chip->trickle_charger_reg);
1818 		regmap_write(ds1307->regmap, chip->trickle_charger_reg,
1819 			     trickle_charger_setup);
1820 	}
1821 
1822 #ifdef CONFIG_OF
1823 /*
1824  * For devices with no IRQ directly connected to the SoC, the RTC chip
1825  * can be forced as a wakeup source by stating that explicitly in
1826  * the device's .dts file using the "wakeup-source" boolean property.
1827  * If the "wakeup-source" property is set, don't request an IRQ.
1828  * This will guarantee the 'wakealarm' sysfs entry is available on the device,
1829  * if supported by the RTC.
1830  */
1831 	if (chip->alarm && of_property_read_bool(client->dev.of_node,
1832 						 "wakeup-source"))
1833 		ds1307_can_wakeup_device = true;
1834 #endif
1835 
1836 	switch (ds1307->type) {
1837 	case ds_1337:
1838 	case ds_1339:
1839 	case ds_1341:
1840 	case ds_3231:
1841 		/* get registers that the "rtc" read below won't read... */
1842 		err = regmap_bulk_read(ds1307->regmap, DS1337_REG_CONTROL,
1843 				       regs, 2);
1844 		if (err) {
1845 			dev_dbg(ds1307->dev, "read error %d\n", err);
1846 			goto exit;
1847 		}
1848 
1849 		/* oscillator off?  turn it on, so clock can tick. */
1850 		if (regs[0] & DS1337_BIT_nEOSC)
1851 			regs[0] &= ~DS1337_BIT_nEOSC;
1852 
1853 		/*
1854 		 * Using IRQ or defined as wakeup-source?
1855 		 * Disable the square wave and both alarms.
1856 		 * For some variants, be sure alarms can trigger when we're
1857 		 * running on Vbackup (BBSQI/BBSQW)
1858 		 */
1859 		if (want_irq || ds1307_can_wakeup_device) {
1860 			regs[0] |= DS1337_BIT_INTCN | chip->bbsqi_bit;
1861 			regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
1862 		}
1863 
1864 		regmap_write(ds1307->regmap, DS1337_REG_CONTROL,
1865 			     regs[0]);
1866 
1867 		/* oscillator fault?  clear flag, and warn */
1868 		if (regs[1] & DS1337_BIT_OSF) {
1869 			regmap_write(ds1307->regmap, DS1337_REG_STATUS,
1870 				     regs[1] & ~DS1337_BIT_OSF);
1871 			dev_warn(ds1307->dev, "SET TIME!\n");
1872 		}
1873 		break;
1874 
1875 	case rx_8025:
1876 		err = regmap_bulk_read(ds1307->regmap,
1877 				       RX8025_REG_CTRL1 << 4 | 0x08, regs, 2);
1878 		if (err) {
1879 			dev_dbg(ds1307->dev, "read error %d\n", err);
1880 			goto exit;
1881 		}
1882 
1883 		/* oscillator off?  turn it on, so clock can tick. */
1884 		if (!(regs[1] & RX8025_BIT_XST)) {
1885 			regs[1] |= RX8025_BIT_XST;
1886 			regmap_write(ds1307->regmap,
1887 				     RX8025_REG_CTRL2 << 4 | 0x08,
1888 				     regs[1]);
1889 			dev_warn(ds1307->dev,
1890 				 "oscillator stop detected - SET TIME!\n");
1891 		}
1892 
1893 		if (regs[1] & RX8025_BIT_PON) {
1894 			regs[1] &= ~RX8025_BIT_PON;
1895 			regmap_write(ds1307->regmap,
1896 				     RX8025_REG_CTRL2 << 4 | 0x08,
1897 				     regs[1]);
1898 			dev_warn(ds1307->dev, "power-on detected\n");
1899 		}
1900 
1901 		if (regs[1] & RX8025_BIT_VDET) {
1902 			regs[1] &= ~RX8025_BIT_VDET;
1903 			regmap_write(ds1307->regmap,
1904 				     RX8025_REG_CTRL2 << 4 | 0x08,
1905 				     regs[1]);
1906 			dev_warn(ds1307->dev, "voltage drop detected\n");
1907 		}
1908 
1909 		/* make sure we are running in 24hour mode */
1910 		if (!(regs[0] & RX8025_BIT_2412)) {
1911 			u8 hour;
1912 
1913 			/* switch to 24 hour mode */
1914 			regmap_write(ds1307->regmap,
1915 				     RX8025_REG_CTRL1 << 4 | 0x08,
1916 				     regs[0] | RX8025_BIT_2412);
1917 
1918 			err = regmap_bulk_read(ds1307->regmap,
1919 					       RX8025_REG_CTRL1 << 4 | 0x08,
1920 					       regs, 2);
1921 			if (err) {
1922 				dev_dbg(ds1307->dev, "read error %d\n", err);
1923 				goto exit;
1924 			}
1925 
1926 			/* correct hour */
1927 			hour = bcd2bin(regs[DS1307_REG_HOUR]);
1928 			if (hour == 12)
1929 				hour = 0;
1930 			if (regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1931 				hour += 12;
1932 
1933 			regmap_write(ds1307->regmap,
1934 				     DS1307_REG_HOUR << 4 | 0x08, hour);
1935 		}
1936 		break;
1937 	case ds_1388:
1938 		err = regmap_read(ds1307->regmap, DS1388_REG_CONTROL, &tmp);
1939 		if (err) {
1940 			dev_dbg(ds1307->dev, "read error %d\n", err);
1941 			goto exit;
1942 		}
1943 
1944 		/* oscillator off?  turn it on, so clock can tick. */
1945 		if (tmp & DS1388_BIT_nEOSC) {
1946 			tmp &= ~DS1388_BIT_nEOSC;
1947 			regmap_write(ds1307->regmap, DS1388_REG_CONTROL, tmp);
1948 		}
1949 		break;
1950 	default:
1951 		break;
1952 	}
1953 
1954 	/* read RTC registers */
1955 	err = regmap_bulk_read(ds1307->regmap, chip->offset, regs,
1956 			       sizeof(regs));
1957 	if (err) {
1958 		dev_dbg(ds1307->dev, "read error %d\n", err);
1959 		goto exit;
1960 	}
1961 
1962 	if (ds1307->type == mcp794xx &&
1963 	    !(regs[DS1307_REG_WDAY] & MCP794XX_BIT_VBATEN)) {
1964 		regmap_write(ds1307->regmap, DS1307_REG_WDAY,
1965 			     regs[DS1307_REG_WDAY] |
1966 			     MCP794XX_BIT_VBATEN);
1967 	}
1968 
1969 	tmp = regs[DS1307_REG_HOUR];
1970 	switch (ds1307->type) {
1971 	case ds_1340:
1972 	case m41t0:
1973 	case m41t00:
1974 	case m41t11:
1975 		/*
1976 		 * NOTE: ignores century bits; fix before deploying
1977 		 * systems that will run through year 2100.
1978 		 */
1979 		break;
1980 	case rx_8025:
1981 		break;
1982 	default:
1983 		if (!(tmp & DS1307_BIT_12HR))
1984 			break;
1985 
1986 		/*
1987 		 * Be sure we're in 24 hour mode.  Multi-master systems
1988 		 * take note...
1989 		 */
1990 		tmp = bcd2bin(tmp & 0x1f);
1991 		if (tmp == 12)
1992 			tmp = 0;
1993 		if (regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1994 			tmp += 12;
1995 		regmap_write(ds1307->regmap, chip->offset + DS1307_REG_HOUR,
1996 			     bin2bcd(tmp));
1997 	}
1998 
1999 	if (want_irq || ds1307_can_wakeup_device) {
2000 		device_set_wakeup_capable(ds1307->dev, true);
2001 		set_bit(HAS_ALARM, &ds1307->flags);
2002 	}
2003 
2004 	ds1307->rtc = devm_rtc_allocate_device(ds1307->dev);
2005 	if (IS_ERR(ds1307->rtc))
2006 		return PTR_ERR(ds1307->rtc);
2007 
2008 	if (ds1307_can_wakeup_device && !want_irq) {
2009 		dev_info(ds1307->dev,
2010 			 "'wakeup-source' is set, request for an IRQ is disabled!\n");
2011 		/* We cannot support UIE mode if we do not have an IRQ line */
2012 		ds1307->rtc->uie_unsupported = 1;
2013 	}
2014 
2015 	if (want_irq) {
2016 		err = devm_request_threaded_irq(ds1307->dev, client->irq, NULL,
2017 						chip->irq_handler ?: ds1307_irq,
2018 						IRQF_SHARED | IRQF_ONESHOT,
2019 						ds1307->name, ds1307);
2020 		if (err) {
2021 			client->irq = 0;
2022 			device_set_wakeup_capable(ds1307->dev, false);
2023 			clear_bit(HAS_ALARM, &ds1307->flags);
2024 			dev_err(ds1307->dev, "unable to request IRQ!\n");
2025 		} else {
2026 			dev_dbg(ds1307->dev, "got IRQ %d\n", client->irq);
2027 		}
2028 	}
2029 
2030 	ds1307->rtc->ops = chip->rtc_ops ?: &ds13xx_rtc_ops;
2031 	err = ds1307_add_frequency_test(ds1307);
2032 	if (err)
2033 		return err;
2034 
2035 	err = rtc_register_device(ds1307->rtc);
2036 	if (err)
2037 		return err;
2038 
2039 	if (chip->nvram_size) {
2040 		struct nvmem_config nvmem_cfg = {
2041 			.name = "ds1307_nvram",
2042 			.word_size = 1,
2043 			.stride = 1,
2044 			.size = chip->nvram_size,
2045 			.reg_read = ds1307_nvram_read,
2046 			.reg_write = ds1307_nvram_write,
2047 			.priv = ds1307,
2048 		};
2049 
2050 		ds1307->rtc->nvram_old_abi = true;
2051 		rtc_nvmem_register(ds1307->rtc, &nvmem_cfg);
2052 	}
2053 
2054 	ds1307_hwmon_register(ds1307);
2055 	ds1307_clks_register(ds1307);
2056 	ds1307_wdt_register(ds1307);
2057 
2058 	return 0;
2059 
2060 exit:
2061 	return err;
2062 }
2063 
2064 static struct i2c_driver ds1307_driver = {
2065 	.driver = {
2066 		.name	= "rtc-ds1307",
2067 		.of_match_table = of_match_ptr(ds1307_of_match),
2068 		.acpi_match_table = ACPI_PTR(ds1307_acpi_ids),
2069 	},
2070 	.probe		= ds1307_probe,
2071 	.id_table	= ds1307_id,
2072 };
2073 
2074 module_i2c_driver(ds1307_driver);
2075 
2076 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
2077 MODULE_LICENSE("GPL");
2078