xref: /linux/drivers/rtc/rtc-ds1307.c (revision 132db93572821ec2fdf81e354cc40f558faf7e4f)
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 
126 #define MCP794XX_REG_CONTROL		0x07
127 #	define MCP794XX_BIT_ALM0_EN	0x10
128 #	define MCP794XX_BIT_ALM1_EN	0x20
129 #define MCP794XX_REG_ALARM0_BASE	0x0a
130 #define MCP794XX_REG_ALARM0_CTRL	0x0d
131 #define MCP794XX_REG_ALARM1_BASE	0x11
132 #define MCP794XX_REG_ALARM1_CTRL	0x14
133 #	define MCP794XX_BIT_ALMX_IF	BIT(3)
134 #	define MCP794XX_BIT_ALMX_C0	BIT(4)
135 #	define MCP794XX_BIT_ALMX_C1	BIT(5)
136 #	define MCP794XX_BIT_ALMX_C2	BIT(6)
137 #	define MCP794XX_BIT_ALMX_POL	BIT(7)
138 #	define MCP794XX_MSK_ALMX_MATCH	(MCP794XX_BIT_ALMX_C0 | \
139 					 MCP794XX_BIT_ALMX_C1 | \
140 					 MCP794XX_BIT_ALMX_C2)
141 
142 #define M41TXX_REG_CONTROL	0x07
143 #	define M41TXX_BIT_OUT		BIT(7)
144 #	define M41TXX_BIT_FT		BIT(6)
145 #	define M41TXX_BIT_CALIB_SIGN	BIT(5)
146 #	define M41TXX_M_CALIBRATION	GENMASK(4, 0)
147 
148 #define DS1388_REG_WDOG_HUN_SECS	0x08
149 #define DS1388_REG_WDOG_SECS		0x09
150 #define DS1388_REG_FLAG			0x0b
151 #	define DS1388_BIT_WF		BIT(6)
152 #	define DS1388_BIT_OSF		BIT(7)
153 #define DS1388_REG_CONTROL		0x0c
154 #	define DS1388_BIT_RST		BIT(0)
155 #	define DS1388_BIT_WDE		BIT(1)
156 
157 /* negative offset step is -2.034ppm */
158 #define M41TXX_NEG_OFFSET_STEP_PPB	2034
159 /* positive offset step is +4.068ppm */
160 #define M41TXX_POS_OFFSET_STEP_PPB	4068
161 /* Min and max values supported with 'offset' interface by M41TXX */
162 #define M41TXX_MIN_OFFSET	((-31) * M41TXX_NEG_OFFSET_STEP_PPB)
163 #define M41TXX_MAX_OFFSET	((31) * M41TXX_POS_OFFSET_STEP_PPB)
164 
165 struct ds1307 {
166 	enum ds_type		type;
167 	unsigned long		flags;
168 #define HAS_NVRAM	0		/* bit 0 == sysfs file active */
169 #define HAS_ALARM	1		/* bit 1 == irq claimed */
170 	struct device		*dev;
171 	struct regmap		*regmap;
172 	const char		*name;
173 	struct rtc_device	*rtc;
174 #ifdef CONFIG_COMMON_CLK
175 	struct clk_hw		clks[2];
176 #endif
177 };
178 
179 struct chip_desc {
180 	unsigned		alarm:1;
181 	u16			nvram_offset;
182 	u16			nvram_size;
183 	u8			offset; /* register's offset */
184 	u8			century_reg;
185 	u8			century_enable_bit;
186 	u8			century_bit;
187 	u8			bbsqi_bit;
188 	irq_handler_t		irq_handler;
189 	const struct rtc_class_ops *rtc_ops;
190 	u16			trickle_charger_reg;
191 	u8			(*do_trickle_setup)(struct ds1307 *, u32,
192 						    bool);
193 };
194 
195 static const struct chip_desc chips[last_ds_type];
196 
197 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
198 {
199 	struct ds1307	*ds1307 = dev_get_drvdata(dev);
200 	int		tmp, ret;
201 	const struct chip_desc *chip = &chips[ds1307->type];
202 	u8 regs[7];
203 
204 	if (ds1307->type == rx_8130) {
205 		unsigned int regflag;
206 		ret = regmap_read(ds1307->regmap, RX8130_REG_FLAG, &regflag);
207 		if (ret) {
208 			dev_err(dev, "%s error %d\n", "read", ret);
209 			return ret;
210 		}
211 
212 		if (regflag & RX8130_REG_FLAG_VLF) {
213 			dev_warn_once(dev, "oscillator failed, set time!\n");
214 			return -EINVAL;
215 		}
216 	}
217 
218 	/* read the RTC date and time registers all at once */
219 	ret = regmap_bulk_read(ds1307->regmap, chip->offset, regs,
220 			       sizeof(regs));
221 	if (ret) {
222 		dev_err(dev, "%s error %d\n", "read", ret);
223 		return ret;
224 	}
225 
226 	dev_dbg(dev, "%s: %7ph\n", "read", regs);
227 
228 	/* if oscillator fail bit is set, no data can be trusted */
229 	if (ds1307->type == m41t0 &&
230 	    regs[DS1307_REG_MIN] & M41T0_BIT_OF) {
231 		dev_warn_once(dev, "oscillator failed, set time!\n");
232 		return -EINVAL;
233 	}
234 
235 	tmp = regs[DS1307_REG_SECS];
236 	switch (ds1307->type) {
237 	case ds_1307:
238 	case m41t0:
239 	case m41t00:
240 	case m41t11:
241 		if (tmp & DS1307_BIT_CH)
242 			return -EINVAL;
243 		break;
244 	case ds_1308:
245 	case ds_1338:
246 		if (tmp & DS1307_BIT_CH)
247 			return -EINVAL;
248 
249 		ret = regmap_read(ds1307->regmap, DS1307_REG_CONTROL, &tmp);
250 		if (ret)
251 			return ret;
252 		if (tmp & DS1338_BIT_OSF)
253 			return -EINVAL;
254 		break;
255 	case ds_1340:
256 		if (tmp & DS1340_BIT_nEOSC)
257 			return -EINVAL;
258 
259 		ret = regmap_read(ds1307->regmap, DS1340_REG_FLAG, &tmp);
260 		if (ret)
261 			return ret;
262 		if (tmp & DS1340_BIT_OSF)
263 			return -EINVAL;
264 		break;
265 	case ds_1388:
266 		ret = regmap_read(ds1307->regmap, DS1388_REG_FLAG, &tmp);
267 		if (ret)
268 			return ret;
269 		if (tmp & DS1388_BIT_OSF)
270 			return -EINVAL;
271 		break;
272 	case mcp794xx:
273 		if (!(tmp & MCP794XX_BIT_ST))
274 			return -EINVAL;
275 
276 		break;
277 	default:
278 		break;
279 	}
280 
281 	t->tm_sec = bcd2bin(regs[DS1307_REG_SECS] & 0x7f);
282 	t->tm_min = bcd2bin(regs[DS1307_REG_MIN] & 0x7f);
283 	tmp = regs[DS1307_REG_HOUR] & 0x3f;
284 	t->tm_hour = bcd2bin(tmp);
285 	t->tm_wday = bcd2bin(regs[DS1307_REG_WDAY] & 0x07) - 1;
286 	t->tm_mday = bcd2bin(regs[DS1307_REG_MDAY] & 0x3f);
287 	tmp = regs[DS1307_REG_MONTH] & 0x1f;
288 	t->tm_mon = bcd2bin(tmp) - 1;
289 	t->tm_year = bcd2bin(regs[DS1307_REG_YEAR]) + 100;
290 
291 	if (regs[chip->century_reg] & chip->century_bit &&
292 	    IS_ENABLED(CONFIG_RTC_DRV_DS1307_CENTURY))
293 		t->tm_year += 100;
294 
295 	dev_dbg(dev, "%s secs=%d, mins=%d, "
296 		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
297 		"read", t->tm_sec, t->tm_min,
298 		t->tm_hour, t->tm_mday,
299 		t->tm_mon, t->tm_year, t->tm_wday);
300 
301 	return 0;
302 }
303 
304 static int ds1307_set_time(struct device *dev, struct rtc_time *t)
305 {
306 	struct ds1307	*ds1307 = dev_get_drvdata(dev);
307 	const struct chip_desc *chip = &chips[ds1307->type];
308 	int		result;
309 	int		tmp;
310 	u8		regs[7];
311 
312 	dev_dbg(dev, "%s secs=%d, mins=%d, "
313 		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
314 		"write", t->tm_sec, t->tm_min,
315 		t->tm_hour, t->tm_mday,
316 		t->tm_mon, t->tm_year, t->tm_wday);
317 
318 	if (t->tm_year < 100)
319 		return -EINVAL;
320 
321 #ifdef CONFIG_RTC_DRV_DS1307_CENTURY
322 	if (t->tm_year > (chip->century_bit ? 299 : 199))
323 		return -EINVAL;
324 #else
325 	if (t->tm_year > 199)
326 		return -EINVAL;
327 #endif
328 
329 	regs[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
330 	regs[DS1307_REG_MIN] = bin2bcd(t->tm_min);
331 	regs[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
332 	regs[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
333 	regs[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
334 	regs[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
335 
336 	/* assume 20YY not 19YY */
337 	tmp = t->tm_year - 100;
338 	regs[DS1307_REG_YEAR] = bin2bcd(tmp);
339 
340 	if (chip->century_enable_bit)
341 		regs[chip->century_reg] |= chip->century_enable_bit;
342 	if (t->tm_year > 199 && chip->century_bit)
343 		regs[chip->century_reg] |= chip->century_bit;
344 
345 	switch (ds1307->type) {
346 	case ds_1308:
347 	case ds_1338:
348 		regmap_update_bits(ds1307->regmap, DS1307_REG_CONTROL,
349 				   DS1338_BIT_OSF, 0);
350 		break;
351 	case ds_1340:
352 		regmap_update_bits(ds1307->regmap, DS1340_REG_FLAG,
353 				   DS1340_BIT_OSF, 0);
354 		break;
355 	case mcp794xx:
356 		/*
357 		 * these bits were cleared when preparing the date/time
358 		 * values and need to be set again before writing the
359 		 * regsfer out to the device.
360 		 */
361 		regs[DS1307_REG_SECS] |= MCP794XX_BIT_ST;
362 		regs[DS1307_REG_WDAY] |= MCP794XX_BIT_VBATEN;
363 		break;
364 	default:
365 		break;
366 	}
367 
368 	dev_dbg(dev, "%s: %7ph\n", "write", regs);
369 
370 	result = regmap_bulk_write(ds1307->regmap, chip->offset, regs,
371 				   sizeof(regs));
372 	if (result) {
373 		dev_err(dev, "%s error %d\n", "write", result);
374 		return result;
375 	}
376 
377 	if (ds1307->type == rx_8130) {
378 		/* clear Voltage Loss Flag as data is available now */
379 		result = regmap_write(ds1307->regmap, RX8130_REG_FLAG,
380 				      ~(u8)RX8130_REG_FLAG_VLF);
381 		if (result) {
382 			dev_err(dev, "%s error %d\n", "write", result);
383 			return result;
384 		}
385 	}
386 
387 	return 0;
388 }
389 
390 static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
391 {
392 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
393 	int			ret;
394 	u8			regs[9];
395 
396 	if (!test_bit(HAS_ALARM, &ds1307->flags))
397 		return -EINVAL;
398 
399 	/* read all ALARM1, ALARM2, and status registers at once */
400 	ret = regmap_bulk_read(ds1307->regmap, DS1339_REG_ALARM1_SECS,
401 			       regs, sizeof(regs));
402 	if (ret) {
403 		dev_err(dev, "%s error %d\n", "alarm read", ret);
404 		return ret;
405 	}
406 
407 	dev_dbg(dev, "%s: %4ph, %3ph, %2ph\n", "alarm read",
408 		&regs[0], &regs[4], &regs[7]);
409 
410 	/*
411 	 * report alarm time (ALARM1); assume 24 hour and day-of-month modes,
412 	 * and that all four fields are checked matches
413 	 */
414 	t->time.tm_sec = bcd2bin(regs[0] & 0x7f);
415 	t->time.tm_min = bcd2bin(regs[1] & 0x7f);
416 	t->time.tm_hour = bcd2bin(regs[2] & 0x3f);
417 	t->time.tm_mday = bcd2bin(regs[3] & 0x3f);
418 
419 	/* ... and status */
420 	t->enabled = !!(regs[7] & DS1337_BIT_A1IE);
421 	t->pending = !!(regs[8] & DS1337_BIT_A1I);
422 
423 	dev_dbg(dev, "%s secs=%d, mins=%d, "
424 		"hours=%d, mday=%d, enabled=%d, pending=%d\n",
425 		"alarm read", t->time.tm_sec, t->time.tm_min,
426 		t->time.tm_hour, t->time.tm_mday,
427 		t->enabled, t->pending);
428 
429 	return 0;
430 }
431 
432 static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
433 {
434 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
435 	unsigned char		regs[9];
436 	u8			control, status;
437 	int			ret;
438 
439 	if (!test_bit(HAS_ALARM, &ds1307->flags))
440 		return -EINVAL;
441 
442 	dev_dbg(dev, "%s secs=%d, mins=%d, "
443 		"hours=%d, mday=%d, enabled=%d, pending=%d\n",
444 		"alarm set", t->time.tm_sec, t->time.tm_min,
445 		t->time.tm_hour, t->time.tm_mday,
446 		t->enabled, t->pending);
447 
448 	/* read current status of both alarms and the chip */
449 	ret = regmap_bulk_read(ds1307->regmap, DS1339_REG_ALARM1_SECS, regs,
450 			       sizeof(regs));
451 	if (ret) {
452 		dev_err(dev, "%s error %d\n", "alarm write", ret);
453 		return ret;
454 	}
455 	control = regs[7];
456 	status = regs[8];
457 
458 	dev_dbg(dev, "%s: %4ph, %3ph, %02x %02x\n", "alarm set (old status)",
459 		&regs[0], &regs[4], control, status);
460 
461 	/* set ALARM1, using 24 hour and day-of-month modes */
462 	regs[0] = bin2bcd(t->time.tm_sec);
463 	regs[1] = bin2bcd(t->time.tm_min);
464 	regs[2] = bin2bcd(t->time.tm_hour);
465 	regs[3] = bin2bcd(t->time.tm_mday);
466 
467 	/* set ALARM2 to non-garbage */
468 	regs[4] = 0;
469 	regs[5] = 0;
470 	regs[6] = 0;
471 
472 	/* disable alarms */
473 	regs[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
474 	regs[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
475 
476 	ret = regmap_bulk_write(ds1307->regmap, DS1339_REG_ALARM1_SECS, regs,
477 				sizeof(regs));
478 	if (ret) {
479 		dev_err(dev, "can't set alarm time\n");
480 		return ret;
481 	}
482 
483 	/* optionally enable ALARM1 */
484 	if (t->enabled) {
485 		dev_dbg(dev, "alarm IRQ armed\n");
486 		regs[7] |= DS1337_BIT_A1IE;	/* only ALARM1 is used */
487 		regmap_write(ds1307->regmap, DS1337_REG_CONTROL, regs[7]);
488 	}
489 
490 	return 0;
491 }
492 
493 static int ds1307_alarm_irq_enable(struct device *dev, unsigned int enabled)
494 {
495 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
496 
497 	if (!test_bit(HAS_ALARM, &ds1307->flags))
498 		return -ENOTTY;
499 
500 	return regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
501 				  DS1337_BIT_A1IE,
502 				  enabled ? DS1337_BIT_A1IE : 0);
503 }
504 
505 static u8 do_trickle_setup_ds1339(struct ds1307 *ds1307, u32 ohms, bool diode)
506 {
507 	u8 setup = (diode) ? DS1307_TRICKLE_CHARGER_DIODE :
508 		DS1307_TRICKLE_CHARGER_NO_DIODE;
509 
510 	switch (ohms) {
511 	case 250:
512 		setup |= DS1307_TRICKLE_CHARGER_250_OHM;
513 		break;
514 	case 2000:
515 		setup |= DS1307_TRICKLE_CHARGER_2K_OHM;
516 		break;
517 	case 4000:
518 		setup |= DS1307_TRICKLE_CHARGER_4K_OHM;
519 		break;
520 	default:
521 		dev_warn(ds1307->dev,
522 			 "Unsupported ohm value %u in dt\n", ohms);
523 		return 0;
524 	}
525 	return setup;
526 }
527 
528 static irqreturn_t rx8130_irq(int irq, void *dev_id)
529 {
530 	struct ds1307           *ds1307 = dev_id;
531 	struct mutex            *lock = &ds1307->rtc->ops_lock;
532 	u8 ctl[3];
533 	int ret;
534 
535 	mutex_lock(lock);
536 
537 	/* Read control registers. */
538 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
539 			       sizeof(ctl));
540 	if (ret < 0)
541 		goto out;
542 	if (!(ctl[1] & RX8130_REG_FLAG_AF))
543 		goto out;
544 	ctl[1] &= ~RX8130_REG_FLAG_AF;
545 	ctl[2] &= ~RX8130_REG_CONTROL0_AIE;
546 
547 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
548 				sizeof(ctl));
549 	if (ret < 0)
550 		goto out;
551 
552 	rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
553 
554 out:
555 	mutex_unlock(lock);
556 
557 	return IRQ_HANDLED;
558 }
559 
560 static int rx8130_read_alarm(struct device *dev, struct rtc_wkalrm *t)
561 {
562 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
563 	u8 ald[3], ctl[3];
564 	int ret;
565 
566 	if (!test_bit(HAS_ALARM, &ds1307->flags))
567 		return -EINVAL;
568 
569 	/* Read alarm registers. */
570 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_ALARM_MIN, ald,
571 			       sizeof(ald));
572 	if (ret < 0)
573 		return ret;
574 
575 	/* Read control registers. */
576 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
577 			       sizeof(ctl));
578 	if (ret < 0)
579 		return ret;
580 
581 	t->enabled = !!(ctl[2] & RX8130_REG_CONTROL0_AIE);
582 	t->pending = !!(ctl[1] & RX8130_REG_FLAG_AF);
583 
584 	/* Report alarm 0 time assuming 24-hour and day-of-month modes. */
585 	t->time.tm_sec = -1;
586 	t->time.tm_min = bcd2bin(ald[0] & 0x7f);
587 	t->time.tm_hour = bcd2bin(ald[1] & 0x7f);
588 	t->time.tm_wday = -1;
589 	t->time.tm_mday = bcd2bin(ald[2] & 0x7f);
590 	t->time.tm_mon = -1;
591 	t->time.tm_year = -1;
592 	t->time.tm_yday = -1;
593 	t->time.tm_isdst = -1;
594 
595 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d enabled=%d\n",
596 		__func__, t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
597 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled);
598 
599 	return 0;
600 }
601 
602 static int rx8130_set_alarm(struct device *dev, struct rtc_wkalrm *t)
603 {
604 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
605 	u8 ald[3], ctl[3];
606 	int ret;
607 
608 	if (!test_bit(HAS_ALARM, &ds1307->flags))
609 		return -EINVAL;
610 
611 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
612 		"enabled=%d pending=%d\n", __func__,
613 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
614 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
615 		t->enabled, t->pending);
616 
617 	/* Read control registers. */
618 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
619 			       sizeof(ctl));
620 	if (ret < 0)
621 		return ret;
622 
623 	ctl[0] &= RX8130_REG_EXTENSION_WADA;
624 	ctl[1] &= ~RX8130_REG_FLAG_AF;
625 	ctl[2] &= ~RX8130_REG_CONTROL0_AIE;
626 
627 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
628 				sizeof(ctl));
629 	if (ret < 0)
630 		return ret;
631 
632 	/* Hardware alarm precision is 1 minute! */
633 	ald[0] = bin2bcd(t->time.tm_min);
634 	ald[1] = bin2bcd(t->time.tm_hour);
635 	ald[2] = bin2bcd(t->time.tm_mday);
636 
637 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_ALARM_MIN, ald,
638 				sizeof(ald));
639 	if (ret < 0)
640 		return ret;
641 
642 	if (!t->enabled)
643 		return 0;
644 
645 	ctl[2] |= RX8130_REG_CONTROL0_AIE;
646 
647 	return regmap_write(ds1307->regmap, RX8130_REG_CONTROL0, ctl[2]);
648 }
649 
650 static int rx8130_alarm_irq_enable(struct device *dev, unsigned int enabled)
651 {
652 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
653 	int ret, reg;
654 
655 	if (!test_bit(HAS_ALARM, &ds1307->flags))
656 		return -EINVAL;
657 
658 	ret = regmap_read(ds1307->regmap, RX8130_REG_CONTROL0, &reg);
659 	if (ret < 0)
660 		return ret;
661 
662 	if (enabled)
663 		reg |= RX8130_REG_CONTROL0_AIE;
664 	else
665 		reg &= ~RX8130_REG_CONTROL0_AIE;
666 
667 	return regmap_write(ds1307->regmap, RX8130_REG_CONTROL0, reg);
668 }
669 
670 static irqreturn_t mcp794xx_irq(int irq, void *dev_id)
671 {
672 	struct ds1307           *ds1307 = dev_id;
673 	struct mutex            *lock = &ds1307->rtc->ops_lock;
674 	int reg, ret;
675 
676 	mutex_lock(lock);
677 
678 	/* Check and clear alarm 0 interrupt flag. */
679 	ret = regmap_read(ds1307->regmap, MCP794XX_REG_ALARM0_CTRL, &reg);
680 	if (ret)
681 		goto out;
682 	if (!(reg & MCP794XX_BIT_ALMX_IF))
683 		goto out;
684 	reg &= ~MCP794XX_BIT_ALMX_IF;
685 	ret = regmap_write(ds1307->regmap, MCP794XX_REG_ALARM0_CTRL, reg);
686 	if (ret)
687 		goto out;
688 
689 	/* Disable alarm 0. */
690 	ret = regmap_update_bits(ds1307->regmap, MCP794XX_REG_CONTROL,
691 				 MCP794XX_BIT_ALM0_EN, 0);
692 	if (ret)
693 		goto out;
694 
695 	rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
696 
697 out:
698 	mutex_unlock(lock);
699 
700 	return IRQ_HANDLED;
701 }
702 
703 static int mcp794xx_read_alarm(struct device *dev, struct rtc_wkalrm *t)
704 {
705 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
706 	u8 regs[10];
707 	int ret;
708 
709 	if (!test_bit(HAS_ALARM, &ds1307->flags))
710 		return -EINVAL;
711 
712 	/* Read control and alarm 0 registers. */
713 	ret = regmap_bulk_read(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
714 			       sizeof(regs));
715 	if (ret)
716 		return ret;
717 
718 	t->enabled = !!(regs[0] & MCP794XX_BIT_ALM0_EN);
719 
720 	/* Report alarm 0 time assuming 24-hour and day-of-month modes. */
721 	t->time.tm_sec = bcd2bin(regs[3] & 0x7f);
722 	t->time.tm_min = bcd2bin(regs[4] & 0x7f);
723 	t->time.tm_hour = bcd2bin(regs[5] & 0x3f);
724 	t->time.tm_wday = bcd2bin(regs[6] & 0x7) - 1;
725 	t->time.tm_mday = bcd2bin(regs[7] & 0x3f);
726 	t->time.tm_mon = bcd2bin(regs[8] & 0x1f) - 1;
727 	t->time.tm_year = -1;
728 	t->time.tm_yday = -1;
729 	t->time.tm_isdst = -1;
730 
731 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
732 		"enabled=%d polarity=%d irq=%d match=%lu\n", __func__,
733 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
734 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled,
735 		!!(regs[6] & MCP794XX_BIT_ALMX_POL),
736 		!!(regs[6] & MCP794XX_BIT_ALMX_IF),
737 		(regs[6] & MCP794XX_MSK_ALMX_MATCH) >> 4);
738 
739 	return 0;
740 }
741 
742 /*
743  * We may have a random RTC weekday, therefore calculate alarm weekday based
744  * on current weekday we read from the RTC timekeeping regs
745  */
746 static int mcp794xx_alm_weekday(struct device *dev, struct rtc_time *tm_alarm)
747 {
748 	struct rtc_time tm_now;
749 	int days_now, days_alarm, ret;
750 
751 	ret = ds1307_get_time(dev, &tm_now);
752 	if (ret)
753 		return ret;
754 
755 	days_now = div_s64(rtc_tm_to_time64(&tm_now), 24 * 60 * 60);
756 	days_alarm = div_s64(rtc_tm_to_time64(tm_alarm), 24 * 60 * 60);
757 
758 	return (tm_now.tm_wday + days_alarm - days_now) % 7 + 1;
759 }
760 
761 static int mcp794xx_set_alarm(struct device *dev, struct rtc_wkalrm *t)
762 {
763 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
764 	unsigned char regs[10];
765 	int wday, ret;
766 
767 	if (!test_bit(HAS_ALARM, &ds1307->flags))
768 		return -EINVAL;
769 
770 	wday = mcp794xx_alm_weekday(dev, &t->time);
771 	if (wday < 0)
772 		return wday;
773 
774 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
775 		"enabled=%d pending=%d\n", __func__,
776 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
777 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
778 		t->enabled, t->pending);
779 
780 	/* Read control and alarm 0 registers. */
781 	ret = regmap_bulk_read(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
782 			       sizeof(regs));
783 	if (ret)
784 		return ret;
785 
786 	/* Set alarm 0, using 24-hour and day-of-month modes. */
787 	regs[3] = bin2bcd(t->time.tm_sec);
788 	regs[4] = bin2bcd(t->time.tm_min);
789 	regs[5] = bin2bcd(t->time.tm_hour);
790 	regs[6] = wday;
791 	regs[7] = bin2bcd(t->time.tm_mday);
792 	regs[8] = bin2bcd(t->time.tm_mon + 1);
793 
794 	/* Clear the alarm 0 interrupt flag. */
795 	regs[6] &= ~MCP794XX_BIT_ALMX_IF;
796 	/* Set alarm match: second, minute, hour, day, date, month. */
797 	regs[6] |= MCP794XX_MSK_ALMX_MATCH;
798 	/* Disable interrupt. We will not enable until completely programmed */
799 	regs[0] &= ~MCP794XX_BIT_ALM0_EN;
800 
801 	ret = regmap_bulk_write(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
802 				sizeof(regs));
803 	if (ret)
804 		return ret;
805 
806 	if (!t->enabled)
807 		return 0;
808 	regs[0] |= MCP794XX_BIT_ALM0_EN;
809 	return regmap_write(ds1307->regmap, MCP794XX_REG_CONTROL, regs[0]);
810 }
811 
812 static int mcp794xx_alarm_irq_enable(struct device *dev, unsigned int enabled)
813 {
814 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
815 
816 	if (!test_bit(HAS_ALARM, &ds1307->flags))
817 		return -EINVAL;
818 
819 	return regmap_update_bits(ds1307->regmap, MCP794XX_REG_CONTROL,
820 				  MCP794XX_BIT_ALM0_EN,
821 				  enabled ? MCP794XX_BIT_ALM0_EN : 0);
822 }
823 
824 static int m41txx_rtc_read_offset(struct device *dev, long *offset)
825 {
826 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
827 	unsigned int ctrl_reg;
828 	u8 val;
829 
830 	regmap_read(ds1307->regmap, M41TXX_REG_CONTROL, &ctrl_reg);
831 
832 	val = ctrl_reg & M41TXX_M_CALIBRATION;
833 
834 	/* check if positive */
835 	if (ctrl_reg & M41TXX_BIT_CALIB_SIGN)
836 		*offset = (val * M41TXX_POS_OFFSET_STEP_PPB);
837 	else
838 		*offset = -(val * M41TXX_NEG_OFFSET_STEP_PPB);
839 
840 	return 0;
841 }
842 
843 static int m41txx_rtc_set_offset(struct device *dev, long offset)
844 {
845 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
846 	unsigned int ctrl_reg;
847 
848 	if ((offset < M41TXX_MIN_OFFSET) || (offset > M41TXX_MAX_OFFSET))
849 		return -ERANGE;
850 
851 	if (offset >= 0) {
852 		ctrl_reg = DIV_ROUND_CLOSEST(offset,
853 					     M41TXX_POS_OFFSET_STEP_PPB);
854 		ctrl_reg |= M41TXX_BIT_CALIB_SIGN;
855 	} else {
856 		ctrl_reg = DIV_ROUND_CLOSEST(abs(offset),
857 					     M41TXX_NEG_OFFSET_STEP_PPB);
858 	}
859 
860 	return regmap_update_bits(ds1307->regmap, M41TXX_REG_CONTROL,
861 				  M41TXX_M_CALIBRATION | M41TXX_BIT_CALIB_SIGN,
862 				  ctrl_reg);
863 }
864 
865 #ifdef CONFIG_WATCHDOG_CORE
866 static int ds1388_wdt_start(struct watchdog_device *wdt_dev)
867 {
868 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
869 	u8 regs[2];
870 	int ret;
871 
872 	ret = regmap_update_bits(ds1307->regmap, DS1388_REG_FLAG,
873 				 DS1388_BIT_WF, 0);
874 	if (ret)
875 		return ret;
876 
877 	ret = regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
878 				 DS1388_BIT_WDE | DS1388_BIT_RST, 0);
879 	if (ret)
880 		return ret;
881 
882 	/*
883 	 * watchdog timeouts are measured in seconds. So ignore hundredths of
884 	 * seconds field.
885 	 */
886 	regs[0] = 0;
887 	regs[1] = bin2bcd(wdt_dev->timeout);
888 
889 	ret = regmap_bulk_write(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
890 				sizeof(regs));
891 	if (ret)
892 		return ret;
893 
894 	return regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
895 				  DS1388_BIT_WDE | DS1388_BIT_RST,
896 				  DS1388_BIT_WDE | DS1388_BIT_RST);
897 }
898 
899 static int ds1388_wdt_stop(struct watchdog_device *wdt_dev)
900 {
901 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
902 
903 	return regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
904 				  DS1388_BIT_WDE | DS1388_BIT_RST, 0);
905 }
906 
907 static int ds1388_wdt_ping(struct watchdog_device *wdt_dev)
908 {
909 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
910 	u8 regs[2];
911 
912 	return regmap_bulk_read(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
913 				sizeof(regs));
914 }
915 
916 static int ds1388_wdt_set_timeout(struct watchdog_device *wdt_dev,
917 				  unsigned int val)
918 {
919 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
920 	u8 regs[2];
921 
922 	wdt_dev->timeout = val;
923 	regs[0] = 0;
924 	regs[1] = bin2bcd(wdt_dev->timeout);
925 
926 	return regmap_bulk_write(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
927 				 sizeof(regs));
928 }
929 #endif
930 
931 static const struct rtc_class_ops rx8130_rtc_ops = {
932 	.read_time      = ds1307_get_time,
933 	.set_time       = ds1307_set_time,
934 	.read_alarm     = rx8130_read_alarm,
935 	.set_alarm      = rx8130_set_alarm,
936 	.alarm_irq_enable = rx8130_alarm_irq_enable,
937 };
938 
939 static const struct rtc_class_ops mcp794xx_rtc_ops = {
940 	.read_time      = ds1307_get_time,
941 	.set_time       = ds1307_set_time,
942 	.read_alarm     = mcp794xx_read_alarm,
943 	.set_alarm      = mcp794xx_set_alarm,
944 	.alarm_irq_enable = mcp794xx_alarm_irq_enable,
945 };
946 
947 static const struct rtc_class_ops m41txx_rtc_ops = {
948 	.read_time      = ds1307_get_time,
949 	.set_time       = ds1307_set_time,
950 	.read_alarm	= ds1337_read_alarm,
951 	.set_alarm	= ds1337_set_alarm,
952 	.alarm_irq_enable = ds1307_alarm_irq_enable,
953 	.read_offset	= m41txx_rtc_read_offset,
954 	.set_offset	= m41txx_rtc_set_offset,
955 };
956 
957 static const struct chip_desc chips[last_ds_type] = {
958 	[ds_1307] = {
959 		.nvram_offset	= 8,
960 		.nvram_size	= 56,
961 	},
962 	[ds_1308] = {
963 		.nvram_offset	= 8,
964 		.nvram_size	= 56,
965 	},
966 	[ds_1337] = {
967 		.alarm		= 1,
968 		.century_reg	= DS1307_REG_MONTH,
969 		.century_bit	= DS1337_BIT_CENTURY,
970 	},
971 	[ds_1338] = {
972 		.nvram_offset	= 8,
973 		.nvram_size	= 56,
974 	},
975 	[ds_1339] = {
976 		.alarm		= 1,
977 		.century_reg	= DS1307_REG_MONTH,
978 		.century_bit	= DS1337_BIT_CENTURY,
979 		.bbsqi_bit	= DS1339_BIT_BBSQI,
980 		.trickle_charger_reg = 0x10,
981 		.do_trickle_setup = &do_trickle_setup_ds1339,
982 	},
983 	[ds_1340] = {
984 		.century_reg	= DS1307_REG_HOUR,
985 		.century_enable_bit = DS1340_BIT_CENTURY_EN,
986 		.century_bit	= DS1340_BIT_CENTURY,
987 		.do_trickle_setup = &do_trickle_setup_ds1339,
988 		.trickle_charger_reg = 0x08,
989 	},
990 	[ds_1341] = {
991 		.century_reg	= DS1307_REG_MONTH,
992 		.century_bit	= DS1337_BIT_CENTURY,
993 	},
994 	[ds_1388] = {
995 		.offset		= 1,
996 		.trickle_charger_reg = 0x0a,
997 	},
998 	[ds_3231] = {
999 		.alarm		= 1,
1000 		.century_reg	= DS1307_REG_MONTH,
1001 		.century_bit	= DS1337_BIT_CENTURY,
1002 		.bbsqi_bit	= DS3231_BIT_BBSQW,
1003 	},
1004 	[rx_8130] = {
1005 		.alarm		= 1,
1006 		/* this is battery backed SRAM */
1007 		.nvram_offset	= 0x20,
1008 		.nvram_size	= 4,	/* 32bit (4 word x 8 bit) */
1009 		.offset		= 0x10,
1010 		.irq_handler = rx8130_irq,
1011 		.rtc_ops = &rx8130_rtc_ops,
1012 	},
1013 	[m41t0] = {
1014 		.rtc_ops	= &m41txx_rtc_ops,
1015 	},
1016 	[m41t00] = {
1017 		.rtc_ops	= &m41txx_rtc_ops,
1018 	},
1019 	[m41t11] = {
1020 		/* this is battery backed SRAM */
1021 		.nvram_offset	= 8,
1022 		.nvram_size	= 56,
1023 		.rtc_ops	= &m41txx_rtc_ops,
1024 	},
1025 	[mcp794xx] = {
1026 		.alarm		= 1,
1027 		/* this is battery backed SRAM */
1028 		.nvram_offset	= 0x20,
1029 		.nvram_size	= 0x40,
1030 		.irq_handler = mcp794xx_irq,
1031 		.rtc_ops = &mcp794xx_rtc_ops,
1032 	},
1033 };
1034 
1035 static const struct i2c_device_id ds1307_id[] = {
1036 	{ "ds1307", ds_1307 },
1037 	{ "ds1308", ds_1308 },
1038 	{ "ds1337", ds_1337 },
1039 	{ "ds1338", ds_1338 },
1040 	{ "ds1339", ds_1339 },
1041 	{ "ds1388", ds_1388 },
1042 	{ "ds1340", ds_1340 },
1043 	{ "ds1341", ds_1341 },
1044 	{ "ds3231", ds_3231 },
1045 	{ "m41t0", m41t0 },
1046 	{ "m41t00", m41t00 },
1047 	{ "m41t11", m41t11 },
1048 	{ "mcp7940x", mcp794xx },
1049 	{ "mcp7941x", mcp794xx },
1050 	{ "pt7c4338", ds_1307 },
1051 	{ "rx8025", rx_8025 },
1052 	{ "isl12057", ds_1337 },
1053 	{ "rx8130", rx_8130 },
1054 	{ }
1055 };
1056 MODULE_DEVICE_TABLE(i2c, ds1307_id);
1057 
1058 #ifdef CONFIG_OF
1059 static const struct of_device_id ds1307_of_match[] = {
1060 	{
1061 		.compatible = "dallas,ds1307",
1062 		.data = (void *)ds_1307
1063 	},
1064 	{
1065 		.compatible = "dallas,ds1308",
1066 		.data = (void *)ds_1308
1067 	},
1068 	{
1069 		.compatible = "dallas,ds1337",
1070 		.data = (void *)ds_1337
1071 	},
1072 	{
1073 		.compatible = "dallas,ds1338",
1074 		.data = (void *)ds_1338
1075 	},
1076 	{
1077 		.compatible = "dallas,ds1339",
1078 		.data = (void *)ds_1339
1079 	},
1080 	{
1081 		.compatible = "dallas,ds1388",
1082 		.data = (void *)ds_1388
1083 	},
1084 	{
1085 		.compatible = "dallas,ds1340",
1086 		.data = (void *)ds_1340
1087 	},
1088 	{
1089 		.compatible = "dallas,ds1341",
1090 		.data = (void *)ds_1341
1091 	},
1092 	{
1093 		.compatible = "maxim,ds3231",
1094 		.data = (void *)ds_3231
1095 	},
1096 	{
1097 		.compatible = "st,m41t0",
1098 		.data = (void *)m41t0
1099 	},
1100 	{
1101 		.compatible = "st,m41t00",
1102 		.data = (void *)m41t00
1103 	},
1104 	{
1105 		.compatible = "st,m41t11",
1106 		.data = (void *)m41t11
1107 	},
1108 	{
1109 		.compatible = "microchip,mcp7940x",
1110 		.data = (void *)mcp794xx
1111 	},
1112 	{
1113 		.compatible = "microchip,mcp7941x",
1114 		.data = (void *)mcp794xx
1115 	},
1116 	{
1117 		.compatible = "pericom,pt7c4338",
1118 		.data = (void *)ds_1307
1119 	},
1120 	{
1121 		.compatible = "epson,rx8025",
1122 		.data = (void *)rx_8025
1123 	},
1124 	{
1125 		.compatible = "isil,isl12057",
1126 		.data = (void *)ds_1337
1127 	},
1128 	{
1129 		.compatible = "epson,rx8130",
1130 		.data = (void *)rx_8130
1131 	},
1132 	{ }
1133 };
1134 MODULE_DEVICE_TABLE(of, ds1307_of_match);
1135 #endif
1136 
1137 #ifdef CONFIG_ACPI
1138 static const struct acpi_device_id ds1307_acpi_ids[] = {
1139 	{ .id = "DS1307", .driver_data = ds_1307 },
1140 	{ .id = "DS1308", .driver_data = ds_1308 },
1141 	{ .id = "DS1337", .driver_data = ds_1337 },
1142 	{ .id = "DS1338", .driver_data = ds_1338 },
1143 	{ .id = "DS1339", .driver_data = ds_1339 },
1144 	{ .id = "DS1388", .driver_data = ds_1388 },
1145 	{ .id = "DS1340", .driver_data = ds_1340 },
1146 	{ .id = "DS1341", .driver_data = ds_1341 },
1147 	{ .id = "DS3231", .driver_data = ds_3231 },
1148 	{ .id = "M41T0", .driver_data = m41t0 },
1149 	{ .id = "M41T00", .driver_data = m41t00 },
1150 	{ .id = "M41T11", .driver_data = m41t11 },
1151 	{ .id = "MCP7940X", .driver_data = mcp794xx },
1152 	{ .id = "MCP7941X", .driver_data = mcp794xx },
1153 	{ .id = "PT7C4338", .driver_data = ds_1307 },
1154 	{ .id = "RX8025", .driver_data = rx_8025 },
1155 	{ .id = "ISL12057", .driver_data = ds_1337 },
1156 	{ .id = "RX8130", .driver_data = rx_8130 },
1157 	{ }
1158 };
1159 MODULE_DEVICE_TABLE(acpi, ds1307_acpi_ids);
1160 #endif
1161 
1162 /*
1163  * The ds1337 and ds1339 both have two alarms, but we only use the first
1164  * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
1165  * signal; ds1339 chips have only one alarm signal.
1166  */
1167 static irqreturn_t ds1307_irq(int irq, void *dev_id)
1168 {
1169 	struct ds1307		*ds1307 = dev_id;
1170 	struct mutex		*lock = &ds1307->rtc->ops_lock;
1171 	int			stat, ret;
1172 
1173 	mutex_lock(lock);
1174 	ret = regmap_read(ds1307->regmap, DS1337_REG_STATUS, &stat);
1175 	if (ret)
1176 		goto out;
1177 
1178 	if (stat & DS1337_BIT_A1I) {
1179 		stat &= ~DS1337_BIT_A1I;
1180 		regmap_write(ds1307->regmap, DS1337_REG_STATUS, stat);
1181 
1182 		ret = regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
1183 					 DS1337_BIT_A1IE, 0);
1184 		if (ret)
1185 			goto out;
1186 
1187 		rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
1188 	}
1189 
1190 out:
1191 	mutex_unlock(lock);
1192 
1193 	return IRQ_HANDLED;
1194 }
1195 
1196 /*----------------------------------------------------------------------*/
1197 
1198 static const struct rtc_class_ops ds13xx_rtc_ops = {
1199 	.read_time	= ds1307_get_time,
1200 	.set_time	= ds1307_set_time,
1201 	.read_alarm	= ds1337_read_alarm,
1202 	.set_alarm	= ds1337_set_alarm,
1203 	.alarm_irq_enable = ds1307_alarm_irq_enable,
1204 };
1205 
1206 static ssize_t frequency_test_store(struct device *dev,
1207 				    struct device_attribute *attr,
1208 				    const char *buf, size_t count)
1209 {
1210 	struct ds1307 *ds1307 = dev_get_drvdata(dev->parent);
1211 	bool freq_test_en;
1212 	int ret;
1213 
1214 	ret = kstrtobool(buf, &freq_test_en);
1215 	if (ret) {
1216 		dev_err(dev, "Failed to store RTC Frequency Test attribute\n");
1217 		return ret;
1218 	}
1219 
1220 	regmap_update_bits(ds1307->regmap, M41TXX_REG_CONTROL, M41TXX_BIT_FT,
1221 			   freq_test_en ? M41TXX_BIT_FT : 0);
1222 
1223 	return count;
1224 }
1225 
1226 static ssize_t frequency_test_show(struct device *dev,
1227 				   struct device_attribute *attr,
1228 				   char *buf)
1229 {
1230 	struct ds1307 *ds1307 = dev_get_drvdata(dev->parent);
1231 	unsigned int ctrl_reg;
1232 
1233 	regmap_read(ds1307->regmap, M41TXX_REG_CONTROL, &ctrl_reg);
1234 
1235 	return scnprintf(buf, PAGE_SIZE, (ctrl_reg & M41TXX_BIT_FT) ? "on\n" :
1236 			"off\n");
1237 }
1238 
1239 static DEVICE_ATTR_RW(frequency_test);
1240 
1241 static struct attribute *rtc_freq_test_attrs[] = {
1242 	&dev_attr_frequency_test.attr,
1243 	NULL,
1244 };
1245 
1246 static const struct attribute_group rtc_freq_test_attr_group = {
1247 	.attrs		= rtc_freq_test_attrs,
1248 };
1249 
1250 static int ds1307_add_frequency_test(struct ds1307 *ds1307)
1251 {
1252 	int err;
1253 
1254 	switch (ds1307->type) {
1255 	case m41t0:
1256 	case m41t00:
1257 	case m41t11:
1258 		err = rtc_add_group(ds1307->rtc, &rtc_freq_test_attr_group);
1259 		if (err)
1260 			return err;
1261 		break;
1262 	default:
1263 		break;
1264 	}
1265 
1266 	return 0;
1267 }
1268 
1269 /*----------------------------------------------------------------------*/
1270 
1271 static int ds1307_nvram_read(void *priv, unsigned int offset, void *val,
1272 			     size_t bytes)
1273 {
1274 	struct ds1307 *ds1307 = priv;
1275 	const struct chip_desc *chip = &chips[ds1307->type];
1276 
1277 	return regmap_bulk_read(ds1307->regmap, chip->nvram_offset + offset,
1278 				val, bytes);
1279 }
1280 
1281 static int ds1307_nvram_write(void *priv, unsigned int offset, void *val,
1282 			      size_t bytes)
1283 {
1284 	struct ds1307 *ds1307 = priv;
1285 	const struct chip_desc *chip = &chips[ds1307->type];
1286 
1287 	return regmap_bulk_write(ds1307->regmap, chip->nvram_offset + offset,
1288 				 val, bytes);
1289 }
1290 
1291 /*----------------------------------------------------------------------*/
1292 
1293 static u8 ds1307_trickle_init(struct ds1307 *ds1307,
1294 			      const struct chip_desc *chip)
1295 {
1296 	u32 ohms;
1297 	bool diode = true;
1298 
1299 	if (!chip->do_trickle_setup)
1300 		return 0;
1301 
1302 	if (device_property_read_u32(ds1307->dev, "trickle-resistor-ohms",
1303 				     &ohms))
1304 		return 0;
1305 
1306 	if (device_property_read_bool(ds1307->dev, "trickle-diode-disable"))
1307 		diode = false;
1308 
1309 	return chip->do_trickle_setup(ds1307, ohms, diode);
1310 }
1311 
1312 /*----------------------------------------------------------------------*/
1313 
1314 #if IS_REACHABLE(CONFIG_HWMON)
1315 
1316 /*
1317  * Temperature sensor support for ds3231 devices.
1318  */
1319 
1320 #define DS3231_REG_TEMPERATURE	0x11
1321 
1322 /*
1323  * A user-initiated temperature conversion is not started by this function,
1324  * so the temperature is updated once every 64 seconds.
1325  */
1326 static int ds3231_hwmon_read_temp(struct device *dev, s32 *mC)
1327 {
1328 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
1329 	u8 temp_buf[2];
1330 	s16 temp;
1331 	int ret;
1332 
1333 	ret = regmap_bulk_read(ds1307->regmap, DS3231_REG_TEMPERATURE,
1334 			       temp_buf, sizeof(temp_buf));
1335 	if (ret)
1336 		return ret;
1337 	/*
1338 	 * Temperature is represented as a 10-bit code with a resolution of
1339 	 * 0.25 degree celsius and encoded in two's complement format.
1340 	 */
1341 	temp = (temp_buf[0] << 8) | temp_buf[1];
1342 	temp >>= 6;
1343 	*mC = temp * 250;
1344 
1345 	return 0;
1346 }
1347 
1348 static ssize_t ds3231_hwmon_show_temp(struct device *dev,
1349 				      struct device_attribute *attr, char *buf)
1350 {
1351 	int ret;
1352 	s32 temp;
1353 
1354 	ret = ds3231_hwmon_read_temp(dev, &temp);
1355 	if (ret)
1356 		return ret;
1357 
1358 	return sprintf(buf, "%d\n", temp);
1359 }
1360 static SENSOR_DEVICE_ATTR(temp1_input, 0444, ds3231_hwmon_show_temp,
1361 			  NULL, 0);
1362 
1363 static struct attribute *ds3231_hwmon_attrs[] = {
1364 	&sensor_dev_attr_temp1_input.dev_attr.attr,
1365 	NULL,
1366 };
1367 ATTRIBUTE_GROUPS(ds3231_hwmon);
1368 
1369 static void ds1307_hwmon_register(struct ds1307 *ds1307)
1370 {
1371 	struct device *dev;
1372 
1373 	if (ds1307->type != ds_3231)
1374 		return;
1375 
1376 	dev = devm_hwmon_device_register_with_groups(ds1307->dev, ds1307->name,
1377 						     ds1307,
1378 						     ds3231_hwmon_groups);
1379 	if (IS_ERR(dev)) {
1380 		dev_warn(ds1307->dev, "unable to register hwmon device %ld\n",
1381 			 PTR_ERR(dev));
1382 	}
1383 }
1384 
1385 #else
1386 
1387 static void ds1307_hwmon_register(struct ds1307 *ds1307)
1388 {
1389 }
1390 
1391 #endif /* CONFIG_RTC_DRV_DS1307_HWMON */
1392 
1393 /*----------------------------------------------------------------------*/
1394 
1395 /*
1396  * Square-wave output support for DS3231
1397  * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS3231.pdf
1398  */
1399 #ifdef CONFIG_COMMON_CLK
1400 
1401 enum {
1402 	DS3231_CLK_SQW = 0,
1403 	DS3231_CLK_32KHZ,
1404 };
1405 
1406 #define clk_sqw_to_ds1307(clk)	\
1407 	container_of(clk, struct ds1307, clks[DS3231_CLK_SQW])
1408 #define clk_32khz_to_ds1307(clk)	\
1409 	container_of(clk, struct ds1307, clks[DS3231_CLK_32KHZ])
1410 
1411 static int ds3231_clk_sqw_rates[] = {
1412 	1,
1413 	1024,
1414 	4096,
1415 	8192,
1416 };
1417 
1418 static int ds1337_write_control(struct ds1307 *ds1307, u8 mask, u8 value)
1419 {
1420 	struct mutex *lock = &ds1307->rtc->ops_lock;
1421 	int ret;
1422 
1423 	mutex_lock(lock);
1424 	ret = regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
1425 				 mask, value);
1426 	mutex_unlock(lock);
1427 
1428 	return ret;
1429 }
1430 
1431 static unsigned long ds3231_clk_sqw_recalc_rate(struct clk_hw *hw,
1432 						unsigned long parent_rate)
1433 {
1434 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1435 	int control, ret;
1436 	int rate_sel = 0;
1437 
1438 	ret = regmap_read(ds1307->regmap, DS1337_REG_CONTROL, &control);
1439 	if (ret)
1440 		return ret;
1441 	if (control & DS1337_BIT_RS1)
1442 		rate_sel += 1;
1443 	if (control & DS1337_BIT_RS2)
1444 		rate_sel += 2;
1445 
1446 	return ds3231_clk_sqw_rates[rate_sel];
1447 }
1448 
1449 static long ds3231_clk_sqw_round_rate(struct clk_hw *hw, unsigned long rate,
1450 				      unsigned long *prate)
1451 {
1452 	int i;
1453 
1454 	for (i = ARRAY_SIZE(ds3231_clk_sqw_rates) - 1; i >= 0; i--) {
1455 		if (ds3231_clk_sqw_rates[i] <= rate)
1456 			return ds3231_clk_sqw_rates[i];
1457 	}
1458 
1459 	return 0;
1460 }
1461 
1462 static int ds3231_clk_sqw_set_rate(struct clk_hw *hw, unsigned long rate,
1463 				   unsigned long parent_rate)
1464 {
1465 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1466 	int control = 0;
1467 	int rate_sel;
1468 
1469 	for (rate_sel = 0; rate_sel < ARRAY_SIZE(ds3231_clk_sqw_rates);
1470 			rate_sel++) {
1471 		if (ds3231_clk_sqw_rates[rate_sel] == rate)
1472 			break;
1473 	}
1474 
1475 	if (rate_sel == ARRAY_SIZE(ds3231_clk_sqw_rates))
1476 		return -EINVAL;
1477 
1478 	if (rate_sel & 1)
1479 		control |= DS1337_BIT_RS1;
1480 	if (rate_sel & 2)
1481 		control |= DS1337_BIT_RS2;
1482 
1483 	return ds1337_write_control(ds1307, DS1337_BIT_RS1 | DS1337_BIT_RS2,
1484 				control);
1485 }
1486 
1487 static int ds3231_clk_sqw_prepare(struct clk_hw *hw)
1488 {
1489 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1490 
1491 	return ds1337_write_control(ds1307, DS1337_BIT_INTCN, 0);
1492 }
1493 
1494 static void ds3231_clk_sqw_unprepare(struct clk_hw *hw)
1495 {
1496 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1497 
1498 	ds1337_write_control(ds1307, DS1337_BIT_INTCN, DS1337_BIT_INTCN);
1499 }
1500 
1501 static int ds3231_clk_sqw_is_prepared(struct clk_hw *hw)
1502 {
1503 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1504 	int control, ret;
1505 
1506 	ret = regmap_read(ds1307->regmap, DS1337_REG_CONTROL, &control);
1507 	if (ret)
1508 		return ret;
1509 
1510 	return !(control & DS1337_BIT_INTCN);
1511 }
1512 
1513 static const struct clk_ops ds3231_clk_sqw_ops = {
1514 	.prepare = ds3231_clk_sqw_prepare,
1515 	.unprepare = ds3231_clk_sqw_unprepare,
1516 	.is_prepared = ds3231_clk_sqw_is_prepared,
1517 	.recalc_rate = ds3231_clk_sqw_recalc_rate,
1518 	.round_rate = ds3231_clk_sqw_round_rate,
1519 	.set_rate = ds3231_clk_sqw_set_rate,
1520 };
1521 
1522 static unsigned long ds3231_clk_32khz_recalc_rate(struct clk_hw *hw,
1523 						  unsigned long parent_rate)
1524 {
1525 	return 32768;
1526 }
1527 
1528 static int ds3231_clk_32khz_control(struct ds1307 *ds1307, bool enable)
1529 {
1530 	struct mutex *lock = &ds1307->rtc->ops_lock;
1531 	int ret;
1532 
1533 	mutex_lock(lock);
1534 	ret = regmap_update_bits(ds1307->regmap, DS1337_REG_STATUS,
1535 				 DS3231_BIT_EN32KHZ,
1536 				 enable ? DS3231_BIT_EN32KHZ : 0);
1537 	mutex_unlock(lock);
1538 
1539 	return ret;
1540 }
1541 
1542 static int ds3231_clk_32khz_prepare(struct clk_hw *hw)
1543 {
1544 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1545 
1546 	return ds3231_clk_32khz_control(ds1307, true);
1547 }
1548 
1549 static void ds3231_clk_32khz_unprepare(struct clk_hw *hw)
1550 {
1551 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1552 
1553 	ds3231_clk_32khz_control(ds1307, false);
1554 }
1555 
1556 static int ds3231_clk_32khz_is_prepared(struct clk_hw *hw)
1557 {
1558 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1559 	int status, ret;
1560 
1561 	ret = regmap_read(ds1307->regmap, DS1337_REG_STATUS, &status);
1562 	if (ret)
1563 		return ret;
1564 
1565 	return !!(status & DS3231_BIT_EN32KHZ);
1566 }
1567 
1568 static const struct clk_ops ds3231_clk_32khz_ops = {
1569 	.prepare = ds3231_clk_32khz_prepare,
1570 	.unprepare = ds3231_clk_32khz_unprepare,
1571 	.is_prepared = ds3231_clk_32khz_is_prepared,
1572 	.recalc_rate = ds3231_clk_32khz_recalc_rate,
1573 };
1574 
1575 static struct clk_init_data ds3231_clks_init[] = {
1576 	[DS3231_CLK_SQW] = {
1577 		.name = "ds3231_clk_sqw",
1578 		.ops = &ds3231_clk_sqw_ops,
1579 	},
1580 	[DS3231_CLK_32KHZ] = {
1581 		.name = "ds3231_clk_32khz",
1582 		.ops = &ds3231_clk_32khz_ops,
1583 	},
1584 };
1585 
1586 static int ds3231_clks_register(struct ds1307 *ds1307)
1587 {
1588 	struct device_node *node = ds1307->dev->of_node;
1589 	struct clk_onecell_data	*onecell;
1590 	int i;
1591 
1592 	onecell = devm_kzalloc(ds1307->dev, sizeof(*onecell), GFP_KERNEL);
1593 	if (!onecell)
1594 		return -ENOMEM;
1595 
1596 	onecell->clk_num = ARRAY_SIZE(ds3231_clks_init);
1597 	onecell->clks = devm_kcalloc(ds1307->dev, onecell->clk_num,
1598 				     sizeof(onecell->clks[0]), GFP_KERNEL);
1599 	if (!onecell->clks)
1600 		return -ENOMEM;
1601 
1602 	for (i = 0; i < ARRAY_SIZE(ds3231_clks_init); i++) {
1603 		struct clk_init_data init = ds3231_clks_init[i];
1604 
1605 		/*
1606 		 * Interrupt signal due to alarm conditions and square-wave
1607 		 * output share same pin, so don't initialize both.
1608 		 */
1609 		if (i == DS3231_CLK_SQW && test_bit(HAS_ALARM, &ds1307->flags))
1610 			continue;
1611 
1612 		/* optional override of the clockname */
1613 		of_property_read_string_index(node, "clock-output-names", i,
1614 					      &init.name);
1615 		ds1307->clks[i].init = &init;
1616 
1617 		onecell->clks[i] = devm_clk_register(ds1307->dev,
1618 						     &ds1307->clks[i]);
1619 		if (IS_ERR(onecell->clks[i]))
1620 			return PTR_ERR(onecell->clks[i]);
1621 	}
1622 
1623 	if (!node)
1624 		return 0;
1625 
1626 	of_clk_add_provider(node, of_clk_src_onecell_get, onecell);
1627 
1628 	return 0;
1629 }
1630 
1631 static void ds1307_clks_register(struct ds1307 *ds1307)
1632 {
1633 	int ret;
1634 
1635 	if (ds1307->type != ds_3231)
1636 		return;
1637 
1638 	ret = ds3231_clks_register(ds1307);
1639 	if (ret) {
1640 		dev_warn(ds1307->dev, "unable to register clock device %d\n",
1641 			 ret);
1642 	}
1643 }
1644 
1645 #else
1646 
1647 static void ds1307_clks_register(struct ds1307 *ds1307)
1648 {
1649 }
1650 
1651 #endif /* CONFIG_COMMON_CLK */
1652 
1653 #ifdef CONFIG_WATCHDOG_CORE
1654 static const struct watchdog_info ds1388_wdt_info = {
1655 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
1656 	.identity = "DS1388 watchdog",
1657 };
1658 
1659 static const struct watchdog_ops ds1388_wdt_ops = {
1660 	.owner = THIS_MODULE,
1661 	.start = ds1388_wdt_start,
1662 	.stop = ds1388_wdt_stop,
1663 	.ping = ds1388_wdt_ping,
1664 	.set_timeout = ds1388_wdt_set_timeout,
1665 
1666 };
1667 
1668 static void ds1307_wdt_register(struct ds1307 *ds1307)
1669 {
1670 	struct watchdog_device	*wdt;
1671 
1672 	if (ds1307->type != ds_1388)
1673 		return;
1674 
1675 	wdt = devm_kzalloc(ds1307->dev, sizeof(*wdt), GFP_KERNEL);
1676 	if (!wdt)
1677 		return;
1678 
1679 	wdt->info = &ds1388_wdt_info;
1680 	wdt->ops = &ds1388_wdt_ops;
1681 	wdt->timeout = 99;
1682 	wdt->max_timeout = 99;
1683 	wdt->min_timeout = 1;
1684 
1685 	watchdog_init_timeout(wdt, 0, ds1307->dev);
1686 	watchdog_set_drvdata(wdt, ds1307);
1687 	devm_watchdog_register_device(ds1307->dev, wdt);
1688 }
1689 #else
1690 static void ds1307_wdt_register(struct ds1307 *ds1307)
1691 {
1692 }
1693 #endif /* CONFIG_WATCHDOG_CORE */
1694 
1695 static const struct regmap_config regmap_config = {
1696 	.reg_bits = 8,
1697 	.val_bits = 8,
1698 };
1699 
1700 static int ds1307_probe(struct i2c_client *client,
1701 			const struct i2c_device_id *id)
1702 {
1703 	struct ds1307		*ds1307;
1704 	int			err = -ENODEV;
1705 	int			tmp;
1706 	const struct chip_desc	*chip;
1707 	bool			want_irq;
1708 	bool			ds1307_can_wakeup_device = false;
1709 	unsigned char		regs[8];
1710 	struct ds1307_platform_data *pdata = dev_get_platdata(&client->dev);
1711 	u8			trickle_charger_setup = 0;
1712 
1713 	ds1307 = devm_kzalloc(&client->dev, sizeof(struct ds1307), GFP_KERNEL);
1714 	if (!ds1307)
1715 		return -ENOMEM;
1716 
1717 	dev_set_drvdata(&client->dev, ds1307);
1718 	ds1307->dev = &client->dev;
1719 	ds1307->name = client->name;
1720 
1721 	ds1307->regmap = devm_regmap_init_i2c(client, &regmap_config);
1722 	if (IS_ERR(ds1307->regmap)) {
1723 		dev_err(ds1307->dev, "regmap allocation failed\n");
1724 		return PTR_ERR(ds1307->regmap);
1725 	}
1726 
1727 	i2c_set_clientdata(client, ds1307);
1728 
1729 	if (client->dev.of_node) {
1730 		ds1307->type = (enum ds_type)
1731 			of_device_get_match_data(&client->dev);
1732 		chip = &chips[ds1307->type];
1733 	} else if (id) {
1734 		chip = &chips[id->driver_data];
1735 		ds1307->type = id->driver_data;
1736 	} else {
1737 		const struct acpi_device_id *acpi_id;
1738 
1739 		acpi_id = acpi_match_device(ACPI_PTR(ds1307_acpi_ids),
1740 					    ds1307->dev);
1741 		if (!acpi_id)
1742 			return -ENODEV;
1743 		chip = &chips[acpi_id->driver_data];
1744 		ds1307->type = acpi_id->driver_data;
1745 	}
1746 
1747 	want_irq = client->irq > 0 && chip->alarm;
1748 
1749 	if (!pdata)
1750 		trickle_charger_setup = ds1307_trickle_init(ds1307, chip);
1751 	else if (pdata->trickle_charger_setup)
1752 		trickle_charger_setup = pdata->trickle_charger_setup;
1753 
1754 	if (trickle_charger_setup && chip->trickle_charger_reg) {
1755 		trickle_charger_setup |= DS13XX_TRICKLE_CHARGER_MAGIC;
1756 		dev_dbg(ds1307->dev,
1757 			"writing trickle charger info 0x%x to 0x%x\n",
1758 			trickle_charger_setup, chip->trickle_charger_reg);
1759 		regmap_write(ds1307->regmap, chip->trickle_charger_reg,
1760 			     trickle_charger_setup);
1761 	}
1762 
1763 #ifdef CONFIG_OF
1764 /*
1765  * For devices with no IRQ directly connected to the SoC, the RTC chip
1766  * can be forced as a wakeup source by stating that explicitly in
1767  * the device's .dts file using the "wakeup-source" boolean property.
1768  * If the "wakeup-source" property is set, don't request an IRQ.
1769  * This will guarantee the 'wakealarm' sysfs entry is available on the device,
1770  * if supported by the RTC.
1771  */
1772 	if (chip->alarm && of_property_read_bool(client->dev.of_node,
1773 						 "wakeup-source"))
1774 		ds1307_can_wakeup_device = true;
1775 #endif
1776 
1777 	switch (ds1307->type) {
1778 	case ds_1337:
1779 	case ds_1339:
1780 	case ds_1341:
1781 	case ds_3231:
1782 		/* get registers that the "rtc" read below won't read... */
1783 		err = regmap_bulk_read(ds1307->regmap, DS1337_REG_CONTROL,
1784 				       regs, 2);
1785 		if (err) {
1786 			dev_dbg(ds1307->dev, "read error %d\n", err);
1787 			goto exit;
1788 		}
1789 
1790 		/* oscillator off?  turn it on, so clock can tick. */
1791 		if (regs[0] & DS1337_BIT_nEOSC)
1792 			regs[0] &= ~DS1337_BIT_nEOSC;
1793 
1794 		/*
1795 		 * Using IRQ or defined as wakeup-source?
1796 		 * Disable the square wave and both alarms.
1797 		 * For some variants, be sure alarms can trigger when we're
1798 		 * running on Vbackup (BBSQI/BBSQW)
1799 		 */
1800 		if (want_irq || ds1307_can_wakeup_device) {
1801 			regs[0] |= DS1337_BIT_INTCN | chip->bbsqi_bit;
1802 			regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
1803 		}
1804 
1805 		regmap_write(ds1307->regmap, DS1337_REG_CONTROL,
1806 			     regs[0]);
1807 
1808 		/* oscillator fault?  clear flag, and warn */
1809 		if (regs[1] & DS1337_BIT_OSF) {
1810 			regmap_write(ds1307->regmap, DS1337_REG_STATUS,
1811 				     regs[1] & ~DS1337_BIT_OSF);
1812 			dev_warn(ds1307->dev, "SET TIME!\n");
1813 		}
1814 		break;
1815 
1816 	case rx_8025:
1817 		err = regmap_bulk_read(ds1307->regmap,
1818 				       RX8025_REG_CTRL1 << 4 | 0x08, regs, 2);
1819 		if (err) {
1820 			dev_dbg(ds1307->dev, "read error %d\n", err);
1821 			goto exit;
1822 		}
1823 
1824 		/* oscillator off?  turn it on, so clock can tick. */
1825 		if (!(regs[1] & RX8025_BIT_XST)) {
1826 			regs[1] |= RX8025_BIT_XST;
1827 			regmap_write(ds1307->regmap,
1828 				     RX8025_REG_CTRL2 << 4 | 0x08,
1829 				     regs[1]);
1830 			dev_warn(ds1307->dev,
1831 				 "oscillator stop detected - SET TIME!\n");
1832 		}
1833 
1834 		if (regs[1] & RX8025_BIT_PON) {
1835 			regs[1] &= ~RX8025_BIT_PON;
1836 			regmap_write(ds1307->regmap,
1837 				     RX8025_REG_CTRL2 << 4 | 0x08,
1838 				     regs[1]);
1839 			dev_warn(ds1307->dev, "power-on detected\n");
1840 		}
1841 
1842 		if (regs[1] & RX8025_BIT_VDET) {
1843 			regs[1] &= ~RX8025_BIT_VDET;
1844 			regmap_write(ds1307->regmap,
1845 				     RX8025_REG_CTRL2 << 4 | 0x08,
1846 				     regs[1]);
1847 			dev_warn(ds1307->dev, "voltage drop detected\n");
1848 		}
1849 
1850 		/* make sure we are running in 24hour mode */
1851 		if (!(regs[0] & RX8025_BIT_2412)) {
1852 			u8 hour;
1853 
1854 			/* switch to 24 hour mode */
1855 			regmap_write(ds1307->regmap,
1856 				     RX8025_REG_CTRL1 << 4 | 0x08,
1857 				     regs[0] | RX8025_BIT_2412);
1858 
1859 			err = regmap_bulk_read(ds1307->regmap,
1860 					       RX8025_REG_CTRL1 << 4 | 0x08,
1861 					       regs, 2);
1862 			if (err) {
1863 				dev_dbg(ds1307->dev, "read error %d\n", err);
1864 				goto exit;
1865 			}
1866 
1867 			/* correct hour */
1868 			hour = bcd2bin(regs[DS1307_REG_HOUR]);
1869 			if (hour == 12)
1870 				hour = 0;
1871 			if (regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1872 				hour += 12;
1873 
1874 			regmap_write(ds1307->regmap,
1875 				     DS1307_REG_HOUR << 4 | 0x08, hour);
1876 		}
1877 		break;
1878 	default:
1879 		break;
1880 	}
1881 
1882 	/* read RTC registers */
1883 	err = regmap_bulk_read(ds1307->regmap, chip->offset, regs,
1884 			       sizeof(regs));
1885 	if (err) {
1886 		dev_dbg(ds1307->dev, "read error %d\n", err);
1887 		goto exit;
1888 	}
1889 
1890 	if (ds1307->type == mcp794xx &&
1891 	    !(regs[DS1307_REG_WDAY] & MCP794XX_BIT_VBATEN)) {
1892 		regmap_write(ds1307->regmap, DS1307_REG_WDAY,
1893 			     regs[DS1307_REG_WDAY] |
1894 			     MCP794XX_BIT_VBATEN);
1895 	}
1896 
1897 	tmp = regs[DS1307_REG_HOUR];
1898 	switch (ds1307->type) {
1899 	case ds_1340:
1900 	case m41t0:
1901 	case m41t00:
1902 	case m41t11:
1903 		/*
1904 		 * NOTE: ignores century bits; fix before deploying
1905 		 * systems that will run through year 2100.
1906 		 */
1907 		break;
1908 	case rx_8025:
1909 		break;
1910 	default:
1911 		if (!(tmp & DS1307_BIT_12HR))
1912 			break;
1913 
1914 		/*
1915 		 * Be sure we're in 24 hour mode.  Multi-master systems
1916 		 * take note...
1917 		 */
1918 		tmp = bcd2bin(tmp & 0x1f);
1919 		if (tmp == 12)
1920 			tmp = 0;
1921 		if (regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1922 			tmp += 12;
1923 		regmap_write(ds1307->regmap, chip->offset + DS1307_REG_HOUR,
1924 			     bin2bcd(tmp));
1925 	}
1926 
1927 	if (want_irq || ds1307_can_wakeup_device) {
1928 		device_set_wakeup_capable(ds1307->dev, true);
1929 		set_bit(HAS_ALARM, &ds1307->flags);
1930 	}
1931 
1932 	ds1307->rtc = devm_rtc_allocate_device(ds1307->dev);
1933 	if (IS_ERR(ds1307->rtc))
1934 		return PTR_ERR(ds1307->rtc);
1935 
1936 	if (ds1307_can_wakeup_device && !want_irq) {
1937 		dev_info(ds1307->dev,
1938 			 "'wakeup-source' is set, request for an IRQ is disabled!\n");
1939 		/* We cannot support UIE mode if we do not have an IRQ line */
1940 		ds1307->rtc->uie_unsupported = 1;
1941 	}
1942 
1943 	if (want_irq) {
1944 		err = devm_request_threaded_irq(ds1307->dev, client->irq, NULL,
1945 						chip->irq_handler ?: ds1307_irq,
1946 						IRQF_SHARED | IRQF_ONESHOT,
1947 						ds1307->name, ds1307);
1948 		if (err) {
1949 			client->irq = 0;
1950 			device_set_wakeup_capable(ds1307->dev, false);
1951 			clear_bit(HAS_ALARM, &ds1307->flags);
1952 			dev_err(ds1307->dev, "unable to request IRQ!\n");
1953 		} else {
1954 			dev_dbg(ds1307->dev, "got IRQ %d\n", client->irq);
1955 		}
1956 	}
1957 
1958 	ds1307->rtc->ops = chip->rtc_ops ?: &ds13xx_rtc_ops;
1959 	err = ds1307_add_frequency_test(ds1307);
1960 	if (err)
1961 		return err;
1962 
1963 	err = rtc_register_device(ds1307->rtc);
1964 	if (err)
1965 		return err;
1966 
1967 	if (chip->nvram_size) {
1968 		struct nvmem_config nvmem_cfg = {
1969 			.name = "ds1307_nvram",
1970 			.word_size = 1,
1971 			.stride = 1,
1972 			.size = chip->nvram_size,
1973 			.reg_read = ds1307_nvram_read,
1974 			.reg_write = ds1307_nvram_write,
1975 			.priv = ds1307,
1976 		};
1977 
1978 		ds1307->rtc->nvram_old_abi = true;
1979 		rtc_nvmem_register(ds1307->rtc, &nvmem_cfg);
1980 	}
1981 
1982 	ds1307_hwmon_register(ds1307);
1983 	ds1307_clks_register(ds1307);
1984 	ds1307_wdt_register(ds1307);
1985 
1986 	return 0;
1987 
1988 exit:
1989 	return err;
1990 }
1991 
1992 static struct i2c_driver ds1307_driver = {
1993 	.driver = {
1994 		.name	= "rtc-ds1307",
1995 		.of_match_table = of_match_ptr(ds1307_of_match),
1996 		.acpi_match_table = ACPI_PTR(ds1307_acpi_ids),
1997 	},
1998 	.probe		= ds1307_probe,
1999 	.id_table	= ds1307_id,
2000 };
2001 
2002 module_i2c_driver(ds1307_driver);
2003 
2004 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
2005 MODULE_LICENSE("GPL");
2006