xref: /openbmc/linux/drivers/rtc/rtc-ds1307.c (revision 4e95bc26)
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 
26 /*
27  * We can't determine type by probing, but if we expect pre-Linux code
28  * to have set the chip up as a clock (turning on the oscillator and
29  * setting the date and time), Linux can ignore the non-clock features.
30  * That's a natural job for a factory or repair bench.
31  */
32 enum ds_type {
33 	ds_1307,
34 	ds_1308,
35 	ds_1337,
36 	ds_1338,
37 	ds_1339,
38 	ds_1340,
39 	ds_1341,
40 	ds_1388,
41 	ds_3231,
42 	m41t0,
43 	m41t00,
44 	m41t11,
45 	mcp794xx,
46 	rx_8025,
47 	rx_8130,
48 	last_ds_type /* always last */
49 	/* rs5c372 too?  different address... */
50 };
51 
52 /* RTC registers don't differ much, except for the century flag */
53 #define DS1307_REG_SECS		0x00	/* 00-59 */
54 #	define DS1307_BIT_CH		0x80
55 #	define DS1340_BIT_nEOSC		0x80
56 #	define MCP794XX_BIT_ST		0x80
57 #define DS1307_REG_MIN		0x01	/* 00-59 */
58 #	define M41T0_BIT_OF		0x80
59 #define DS1307_REG_HOUR		0x02	/* 00-23, or 1-12{am,pm} */
60 #	define DS1307_BIT_12HR		0x40	/* in REG_HOUR */
61 #	define DS1307_BIT_PM		0x20	/* in REG_HOUR */
62 #	define DS1340_BIT_CENTURY_EN	0x80	/* in REG_HOUR */
63 #	define DS1340_BIT_CENTURY	0x40	/* in REG_HOUR */
64 #define DS1307_REG_WDAY		0x03	/* 01-07 */
65 #	define MCP794XX_BIT_VBATEN	0x08
66 #define DS1307_REG_MDAY		0x04	/* 01-31 */
67 #define DS1307_REG_MONTH	0x05	/* 01-12 */
68 #	define DS1337_BIT_CENTURY	0x80	/* in REG_MONTH */
69 #define DS1307_REG_YEAR		0x06	/* 00-99 */
70 
71 /*
72  * Other registers (control, status, alarms, trickle charge, NVRAM, etc)
73  * start at 7, and they differ a LOT. Only control and status matter for
74  * basic RTC date and time functionality; be careful using them.
75  */
76 #define DS1307_REG_CONTROL	0x07		/* or ds1338 */
77 #	define DS1307_BIT_OUT		0x80
78 #	define DS1338_BIT_OSF		0x20
79 #	define DS1307_BIT_SQWE		0x10
80 #	define DS1307_BIT_RS1		0x02
81 #	define DS1307_BIT_RS0		0x01
82 #define DS1337_REG_CONTROL	0x0e
83 #	define DS1337_BIT_nEOSC		0x80
84 #	define DS1339_BIT_BBSQI		0x20
85 #	define DS3231_BIT_BBSQW		0x40 /* same as BBSQI */
86 #	define DS1337_BIT_RS2		0x10
87 #	define DS1337_BIT_RS1		0x08
88 #	define DS1337_BIT_INTCN		0x04
89 #	define DS1337_BIT_A2IE		0x02
90 #	define DS1337_BIT_A1IE		0x01
91 #define DS1340_REG_CONTROL	0x07
92 #	define DS1340_BIT_OUT		0x80
93 #	define DS1340_BIT_FT		0x40
94 #	define DS1340_BIT_CALIB_SIGN	0x20
95 #	define DS1340_M_CALIBRATION	0x1f
96 #define DS1340_REG_FLAG		0x09
97 #	define DS1340_BIT_OSF		0x80
98 #define DS1337_REG_STATUS	0x0f
99 #	define DS1337_BIT_OSF		0x80
100 #	define DS3231_BIT_EN32KHZ	0x08
101 #	define DS1337_BIT_A2I		0x02
102 #	define DS1337_BIT_A1I		0x01
103 #define DS1339_REG_ALARM1_SECS	0x07
104 
105 #define DS13XX_TRICKLE_CHARGER_MAGIC	0xa0
106 
107 #define RX8025_REG_CTRL1	0x0e
108 #	define RX8025_BIT_2412		0x20
109 #define RX8025_REG_CTRL2	0x0f
110 #	define RX8025_BIT_PON		0x10
111 #	define RX8025_BIT_VDET		0x40
112 #	define RX8025_BIT_XST		0x20
113 
114 #define RX8130_REG_ALARM_MIN		0x17
115 #define RX8130_REG_ALARM_HOUR		0x18
116 #define RX8130_REG_ALARM_WEEK_OR_DAY	0x19
117 #define RX8130_REG_EXTENSION		0x1c
118 #define RX8130_REG_EXTENSION_WADA	BIT(3)
119 #define RX8130_REG_FLAG			0x1d
120 #define RX8130_REG_FLAG_VLF		BIT(1)
121 #define RX8130_REG_FLAG_AF		BIT(3)
122 #define RX8130_REG_CONTROL0		0x1e
123 #define RX8130_REG_CONTROL0_AIE		BIT(3)
124 
125 #define MCP794XX_REG_CONTROL		0x07
126 #	define MCP794XX_BIT_ALM0_EN	0x10
127 #	define MCP794XX_BIT_ALM1_EN	0x20
128 #define MCP794XX_REG_ALARM0_BASE	0x0a
129 #define MCP794XX_REG_ALARM0_CTRL	0x0d
130 #define MCP794XX_REG_ALARM1_BASE	0x11
131 #define MCP794XX_REG_ALARM1_CTRL	0x14
132 #	define MCP794XX_BIT_ALMX_IF	BIT(3)
133 #	define MCP794XX_BIT_ALMX_C0	BIT(4)
134 #	define MCP794XX_BIT_ALMX_C1	BIT(5)
135 #	define MCP794XX_BIT_ALMX_C2	BIT(6)
136 #	define MCP794XX_BIT_ALMX_POL	BIT(7)
137 #	define MCP794XX_MSK_ALMX_MATCH	(MCP794XX_BIT_ALMX_C0 | \
138 					 MCP794XX_BIT_ALMX_C1 | \
139 					 MCP794XX_BIT_ALMX_C2)
140 
141 #define M41TXX_REG_CONTROL	0x07
142 #	define M41TXX_BIT_OUT		BIT(7)
143 #	define M41TXX_BIT_FT		BIT(6)
144 #	define M41TXX_BIT_CALIB_SIGN	BIT(5)
145 #	define M41TXX_M_CALIBRATION	GENMASK(4, 0)
146 
147 /* negative offset step is -2.034ppm */
148 #define M41TXX_NEG_OFFSET_STEP_PPB	2034
149 /* positive offset step is +4.068ppm */
150 #define M41TXX_POS_OFFSET_STEP_PPB	4068
151 /* Min and max values supported with 'offset' interface by M41TXX */
152 #define M41TXX_MIN_OFFSET	((-31) * M41TXX_NEG_OFFSET_STEP_PPB)
153 #define M41TXX_MAX_OFFSET	((31) * M41TXX_POS_OFFSET_STEP_PPB)
154 
155 struct ds1307 {
156 	enum ds_type		type;
157 	unsigned long		flags;
158 #define HAS_NVRAM	0		/* bit 0 == sysfs file active */
159 #define HAS_ALARM	1		/* bit 1 == irq claimed */
160 	struct device		*dev;
161 	struct regmap		*regmap;
162 	const char		*name;
163 	struct rtc_device	*rtc;
164 #ifdef CONFIG_COMMON_CLK
165 	struct clk_hw		clks[2];
166 #endif
167 };
168 
169 struct chip_desc {
170 	unsigned		alarm:1;
171 	u16			nvram_offset;
172 	u16			nvram_size;
173 	u8			offset; /* register's offset */
174 	u8			century_reg;
175 	u8			century_enable_bit;
176 	u8			century_bit;
177 	u8			bbsqi_bit;
178 	irq_handler_t		irq_handler;
179 	const struct rtc_class_ops *rtc_ops;
180 	u16			trickle_charger_reg;
181 	u8			(*do_trickle_setup)(struct ds1307 *, u32,
182 						    bool);
183 };
184 
185 static const struct chip_desc chips[last_ds_type];
186 
187 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
188 {
189 	struct ds1307	*ds1307 = dev_get_drvdata(dev);
190 	int		tmp, ret;
191 	const struct chip_desc *chip = &chips[ds1307->type];
192 	u8 regs[7];
193 
194 	if (ds1307->type == rx_8130) {
195 		unsigned int regflag;
196 		ret = regmap_read(ds1307->regmap, RX8130_REG_FLAG, &regflag);
197 		if (ret) {
198 			dev_err(dev, "%s error %d\n", "read", ret);
199 			return ret;
200 		}
201 
202 		if (regflag & RX8130_REG_FLAG_VLF) {
203 			dev_warn_once(dev, "oscillator failed, set time!\n");
204 			return -EINVAL;
205 		}
206 	}
207 
208 	/* read the RTC date and time registers all at once */
209 	ret = regmap_bulk_read(ds1307->regmap, chip->offset, regs,
210 			       sizeof(regs));
211 	if (ret) {
212 		dev_err(dev, "%s error %d\n", "read", ret);
213 		return ret;
214 	}
215 
216 	dev_dbg(dev, "%s: %7ph\n", "read", regs);
217 
218 	/* if oscillator fail bit is set, no data can be trusted */
219 	if (ds1307->type == m41t0 &&
220 	    regs[DS1307_REG_MIN] & M41T0_BIT_OF) {
221 		dev_warn_once(dev, "oscillator failed, set time!\n");
222 		return -EINVAL;
223 	}
224 
225 	t->tm_sec = bcd2bin(regs[DS1307_REG_SECS] & 0x7f);
226 	t->tm_min = bcd2bin(regs[DS1307_REG_MIN] & 0x7f);
227 	tmp = regs[DS1307_REG_HOUR] & 0x3f;
228 	t->tm_hour = bcd2bin(tmp);
229 	t->tm_wday = bcd2bin(regs[DS1307_REG_WDAY] & 0x07) - 1;
230 	t->tm_mday = bcd2bin(regs[DS1307_REG_MDAY] & 0x3f);
231 	tmp = regs[DS1307_REG_MONTH] & 0x1f;
232 	t->tm_mon = bcd2bin(tmp) - 1;
233 	t->tm_year = bcd2bin(regs[DS1307_REG_YEAR]) + 100;
234 
235 	if (regs[chip->century_reg] & chip->century_bit &&
236 	    IS_ENABLED(CONFIG_RTC_DRV_DS1307_CENTURY))
237 		t->tm_year += 100;
238 
239 	dev_dbg(dev, "%s secs=%d, mins=%d, "
240 		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
241 		"read", t->tm_sec, t->tm_min,
242 		t->tm_hour, t->tm_mday,
243 		t->tm_mon, t->tm_year, t->tm_wday);
244 
245 	return 0;
246 }
247 
248 static int ds1307_set_time(struct device *dev, struct rtc_time *t)
249 {
250 	struct ds1307	*ds1307 = dev_get_drvdata(dev);
251 	const struct chip_desc *chip = &chips[ds1307->type];
252 	int		result;
253 	int		tmp;
254 	u8		regs[7];
255 
256 	dev_dbg(dev, "%s secs=%d, mins=%d, "
257 		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
258 		"write", t->tm_sec, t->tm_min,
259 		t->tm_hour, t->tm_mday,
260 		t->tm_mon, t->tm_year, t->tm_wday);
261 
262 	if (t->tm_year < 100)
263 		return -EINVAL;
264 
265 #ifdef CONFIG_RTC_DRV_DS1307_CENTURY
266 	if (t->tm_year > (chip->century_bit ? 299 : 199))
267 		return -EINVAL;
268 #else
269 	if (t->tm_year > 199)
270 		return -EINVAL;
271 #endif
272 
273 	regs[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
274 	regs[DS1307_REG_MIN] = bin2bcd(t->tm_min);
275 	regs[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
276 	regs[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
277 	regs[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
278 	regs[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
279 
280 	/* assume 20YY not 19YY */
281 	tmp = t->tm_year - 100;
282 	regs[DS1307_REG_YEAR] = bin2bcd(tmp);
283 
284 	if (chip->century_enable_bit)
285 		regs[chip->century_reg] |= chip->century_enable_bit;
286 	if (t->tm_year > 199 && chip->century_bit)
287 		regs[chip->century_reg] |= chip->century_bit;
288 
289 	if (ds1307->type == mcp794xx) {
290 		/*
291 		 * these bits were cleared when preparing the date/time
292 		 * values and need to be set again before writing the
293 		 * regsfer out to the device.
294 		 */
295 		regs[DS1307_REG_SECS] |= MCP794XX_BIT_ST;
296 		regs[DS1307_REG_WDAY] |= MCP794XX_BIT_VBATEN;
297 	}
298 
299 	dev_dbg(dev, "%s: %7ph\n", "write", regs);
300 
301 	result = regmap_bulk_write(ds1307->regmap, chip->offset, regs,
302 				   sizeof(regs));
303 	if (result) {
304 		dev_err(dev, "%s error %d\n", "write", result);
305 		return result;
306 	}
307 
308 	if (ds1307->type == rx_8130) {
309 		/* clear Voltage Loss Flag as data is available now */
310 		result = regmap_write(ds1307->regmap, RX8130_REG_FLAG,
311 				      ~(u8)RX8130_REG_FLAG_VLF);
312 		if (result) {
313 			dev_err(dev, "%s error %d\n", "write", result);
314 			return result;
315 		}
316 	}
317 
318 	return 0;
319 }
320 
321 static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
322 {
323 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
324 	int			ret;
325 	u8			regs[9];
326 
327 	if (!test_bit(HAS_ALARM, &ds1307->flags))
328 		return -EINVAL;
329 
330 	/* read all ALARM1, ALARM2, and status registers at once */
331 	ret = regmap_bulk_read(ds1307->regmap, DS1339_REG_ALARM1_SECS,
332 			       regs, sizeof(regs));
333 	if (ret) {
334 		dev_err(dev, "%s error %d\n", "alarm read", ret);
335 		return ret;
336 	}
337 
338 	dev_dbg(dev, "%s: %4ph, %3ph, %2ph\n", "alarm read",
339 		&regs[0], &regs[4], &regs[7]);
340 
341 	/*
342 	 * report alarm time (ALARM1); assume 24 hour and day-of-month modes,
343 	 * and that all four fields are checked matches
344 	 */
345 	t->time.tm_sec = bcd2bin(regs[0] & 0x7f);
346 	t->time.tm_min = bcd2bin(regs[1] & 0x7f);
347 	t->time.tm_hour = bcd2bin(regs[2] & 0x3f);
348 	t->time.tm_mday = bcd2bin(regs[3] & 0x3f);
349 
350 	/* ... and status */
351 	t->enabled = !!(regs[7] & DS1337_BIT_A1IE);
352 	t->pending = !!(regs[8] & DS1337_BIT_A1I);
353 
354 	dev_dbg(dev, "%s secs=%d, mins=%d, "
355 		"hours=%d, mday=%d, enabled=%d, pending=%d\n",
356 		"alarm read", t->time.tm_sec, t->time.tm_min,
357 		t->time.tm_hour, t->time.tm_mday,
358 		t->enabled, t->pending);
359 
360 	return 0;
361 }
362 
363 static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
364 {
365 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
366 	unsigned char		regs[9];
367 	u8			control, status;
368 	int			ret;
369 
370 	if (!test_bit(HAS_ALARM, &ds1307->flags))
371 		return -EINVAL;
372 
373 	dev_dbg(dev, "%s secs=%d, mins=%d, "
374 		"hours=%d, mday=%d, enabled=%d, pending=%d\n",
375 		"alarm set", t->time.tm_sec, t->time.tm_min,
376 		t->time.tm_hour, t->time.tm_mday,
377 		t->enabled, t->pending);
378 
379 	/* read current status of both alarms and the chip */
380 	ret = regmap_bulk_read(ds1307->regmap, DS1339_REG_ALARM1_SECS, regs,
381 			       sizeof(regs));
382 	if (ret) {
383 		dev_err(dev, "%s error %d\n", "alarm write", ret);
384 		return ret;
385 	}
386 	control = regs[7];
387 	status = regs[8];
388 
389 	dev_dbg(dev, "%s: %4ph, %3ph, %02x %02x\n", "alarm set (old status)",
390 		&regs[0], &regs[4], control, status);
391 
392 	/* set ALARM1, using 24 hour and day-of-month modes */
393 	regs[0] = bin2bcd(t->time.tm_sec);
394 	regs[1] = bin2bcd(t->time.tm_min);
395 	regs[2] = bin2bcd(t->time.tm_hour);
396 	regs[3] = bin2bcd(t->time.tm_mday);
397 
398 	/* set ALARM2 to non-garbage */
399 	regs[4] = 0;
400 	regs[5] = 0;
401 	regs[6] = 0;
402 
403 	/* disable alarms */
404 	regs[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
405 	regs[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
406 
407 	ret = regmap_bulk_write(ds1307->regmap, DS1339_REG_ALARM1_SECS, regs,
408 				sizeof(regs));
409 	if (ret) {
410 		dev_err(dev, "can't set alarm time\n");
411 		return ret;
412 	}
413 
414 	/* optionally enable ALARM1 */
415 	if (t->enabled) {
416 		dev_dbg(dev, "alarm IRQ armed\n");
417 		regs[7] |= DS1337_BIT_A1IE;	/* only ALARM1 is used */
418 		regmap_write(ds1307->regmap, DS1337_REG_CONTROL, regs[7]);
419 	}
420 
421 	return 0;
422 }
423 
424 static int ds1307_alarm_irq_enable(struct device *dev, unsigned int enabled)
425 {
426 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
427 
428 	if (!test_bit(HAS_ALARM, &ds1307->flags))
429 		return -ENOTTY;
430 
431 	return regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
432 				  DS1337_BIT_A1IE,
433 				  enabled ? DS1337_BIT_A1IE : 0);
434 }
435 
436 static u8 do_trickle_setup_ds1339(struct ds1307 *ds1307, u32 ohms, bool diode)
437 {
438 	u8 setup = (diode) ? DS1307_TRICKLE_CHARGER_DIODE :
439 		DS1307_TRICKLE_CHARGER_NO_DIODE;
440 
441 	switch (ohms) {
442 	case 250:
443 		setup |= DS1307_TRICKLE_CHARGER_250_OHM;
444 		break;
445 	case 2000:
446 		setup |= DS1307_TRICKLE_CHARGER_2K_OHM;
447 		break;
448 	case 4000:
449 		setup |= DS1307_TRICKLE_CHARGER_4K_OHM;
450 		break;
451 	default:
452 		dev_warn(ds1307->dev,
453 			 "Unsupported ohm value %u in dt\n", ohms);
454 		return 0;
455 	}
456 	return setup;
457 }
458 
459 static irqreturn_t rx8130_irq(int irq, void *dev_id)
460 {
461 	struct ds1307           *ds1307 = dev_id;
462 	struct mutex            *lock = &ds1307->rtc->ops_lock;
463 	u8 ctl[3];
464 	int ret;
465 
466 	mutex_lock(lock);
467 
468 	/* Read control registers. */
469 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
470 			       sizeof(ctl));
471 	if (ret < 0)
472 		goto out;
473 	if (!(ctl[1] & RX8130_REG_FLAG_AF))
474 		goto out;
475 	ctl[1] &= ~RX8130_REG_FLAG_AF;
476 	ctl[2] &= ~RX8130_REG_CONTROL0_AIE;
477 
478 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
479 				sizeof(ctl));
480 	if (ret < 0)
481 		goto out;
482 
483 	rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
484 
485 out:
486 	mutex_unlock(lock);
487 
488 	return IRQ_HANDLED;
489 }
490 
491 static int rx8130_read_alarm(struct device *dev, struct rtc_wkalrm *t)
492 {
493 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
494 	u8 ald[3], ctl[3];
495 	int ret;
496 
497 	if (!test_bit(HAS_ALARM, &ds1307->flags))
498 		return -EINVAL;
499 
500 	/* Read alarm registers. */
501 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_ALARM_MIN, ald,
502 			       sizeof(ald));
503 	if (ret < 0)
504 		return ret;
505 
506 	/* Read control registers. */
507 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
508 			       sizeof(ctl));
509 	if (ret < 0)
510 		return ret;
511 
512 	t->enabled = !!(ctl[2] & RX8130_REG_CONTROL0_AIE);
513 	t->pending = !!(ctl[1] & RX8130_REG_FLAG_AF);
514 
515 	/* Report alarm 0 time assuming 24-hour and day-of-month modes. */
516 	t->time.tm_sec = -1;
517 	t->time.tm_min = bcd2bin(ald[0] & 0x7f);
518 	t->time.tm_hour = bcd2bin(ald[1] & 0x7f);
519 	t->time.tm_wday = -1;
520 	t->time.tm_mday = bcd2bin(ald[2] & 0x7f);
521 	t->time.tm_mon = -1;
522 	t->time.tm_year = -1;
523 	t->time.tm_yday = -1;
524 	t->time.tm_isdst = -1;
525 
526 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d enabled=%d\n",
527 		__func__, t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
528 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled);
529 
530 	return 0;
531 }
532 
533 static int rx8130_set_alarm(struct device *dev, struct rtc_wkalrm *t)
534 {
535 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
536 	u8 ald[3], ctl[3];
537 	int ret;
538 
539 	if (!test_bit(HAS_ALARM, &ds1307->flags))
540 		return -EINVAL;
541 
542 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
543 		"enabled=%d pending=%d\n", __func__,
544 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
545 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
546 		t->enabled, t->pending);
547 
548 	/* Read control registers. */
549 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
550 			       sizeof(ctl));
551 	if (ret < 0)
552 		return ret;
553 
554 	ctl[0] &= RX8130_REG_EXTENSION_WADA;
555 	ctl[1] &= ~RX8130_REG_FLAG_AF;
556 	ctl[2] &= ~RX8130_REG_CONTROL0_AIE;
557 
558 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
559 				sizeof(ctl));
560 	if (ret < 0)
561 		return ret;
562 
563 	/* Hardware alarm precision is 1 minute! */
564 	ald[0] = bin2bcd(t->time.tm_min);
565 	ald[1] = bin2bcd(t->time.tm_hour);
566 	ald[2] = bin2bcd(t->time.tm_mday);
567 
568 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_ALARM_MIN, ald,
569 				sizeof(ald));
570 	if (ret < 0)
571 		return ret;
572 
573 	if (!t->enabled)
574 		return 0;
575 
576 	ctl[2] |= RX8130_REG_CONTROL0_AIE;
577 
578 	return regmap_write(ds1307->regmap, RX8130_REG_CONTROL0, ctl[2]);
579 }
580 
581 static int rx8130_alarm_irq_enable(struct device *dev, unsigned int enabled)
582 {
583 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
584 	int ret, reg;
585 
586 	if (!test_bit(HAS_ALARM, &ds1307->flags))
587 		return -EINVAL;
588 
589 	ret = regmap_read(ds1307->regmap, RX8130_REG_CONTROL0, &reg);
590 	if (ret < 0)
591 		return ret;
592 
593 	if (enabled)
594 		reg |= RX8130_REG_CONTROL0_AIE;
595 	else
596 		reg &= ~RX8130_REG_CONTROL0_AIE;
597 
598 	return regmap_write(ds1307->regmap, RX8130_REG_CONTROL0, reg);
599 }
600 
601 static irqreturn_t mcp794xx_irq(int irq, void *dev_id)
602 {
603 	struct ds1307           *ds1307 = dev_id;
604 	struct mutex            *lock = &ds1307->rtc->ops_lock;
605 	int reg, ret;
606 
607 	mutex_lock(lock);
608 
609 	/* Check and clear alarm 0 interrupt flag. */
610 	ret = regmap_read(ds1307->regmap, MCP794XX_REG_ALARM0_CTRL, &reg);
611 	if (ret)
612 		goto out;
613 	if (!(reg & MCP794XX_BIT_ALMX_IF))
614 		goto out;
615 	reg &= ~MCP794XX_BIT_ALMX_IF;
616 	ret = regmap_write(ds1307->regmap, MCP794XX_REG_ALARM0_CTRL, reg);
617 	if (ret)
618 		goto out;
619 
620 	/* Disable alarm 0. */
621 	ret = regmap_update_bits(ds1307->regmap, MCP794XX_REG_CONTROL,
622 				 MCP794XX_BIT_ALM0_EN, 0);
623 	if (ret)
624 		goto out;
625 
626 	rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
627 
628 out:
629 	mutex_unlock(lock);
630 
631 	return IRQ_HANDLED;
632 }
633 
634 static int mcp794xx_read_alarm(struct device *dev, struct rtc_wkalrm *t)
635 {
636 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
637 	u8 regs[10];
638 	int ret;
639 
640 	if (!test_bit(HAS_ALARM, &ds1307->flags))
641 		return -EINVAL;
642 
643 	/* Read control and alarm 0 registers. */
644 	ret = regmap_bulk_read(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
645 			       sizeof(regs));
646 	if (ret)
647 		return ret;
648 
649 	t->enabled = !!(regs[0] & MCP794XX_BIT_ALM0_EN);
650 
651 	/* Report alarm 0 time assuming 24-hour and day-of-month modes. */
652 	t->time.tm_sec = bcd2bin(regs[3] & 0x7f);
653 	t->time.tm_min = bcd2bin(regs[4] & 0x7f);
654 	t->time.tm_hour = bcd2bin(regs[5] & 0x3f);
655 	t->time.tm_wday = bcd2bin(regs[6] & 0x7) - 1;
656 	t->time.tm_mday = bcd2bin(regs[7] & 0x3f);
657 	t->time.tm_mon = bcd2bin(regs[8] & 0x1f) - 1;
658 	t->time.tm_year = -1;
659 	t->time.tm_yday = -1;
660 	t->time.tm_isdst = -1;
661 
662 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
663 		"enabled=%d polarity=%d irq=%d match=%lu\n", __func__,
664 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
665 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled,
666 		!!(regs[6] & MCP794XX_BIT_ALMX_POL),
667 		!!(regs[6] & MCP794XX_BIT_ALMX_IF),
668 		(regs[6] & MCP794XX_MSK_ALMX_MATCH) >> 4);
669 
670 	return 0;
671 }
672 
673 /*
674  * We may have a random RTC weekday, therefore calculate alarm weekday based
675  * on current weekday we read from the RTC timekeeping regs
676  */
677 static int mcp794xx_alm_weekday(struct device *dev, struct rtc_time *tm_alarm)
678 {
679 	struct rtc_time tm_now;
680 	int days_now, days_alarm, ret;
681 
682 	ret = ds1307_get_time(dev, &tm_now);
683 	if (ret)
684 		return ret;
685 
686 	days_now = div_s64(rtc_tm_to_time64(&tm_now), 24 * 60 * 60);
687 	days_alarm = div_s64(rtc_tm_to_time64(tm_alarm), 24 * 60 * 60);
688 
689 	return (tm_now.tm_wday + days_alarm - days_now) % 7 + 1;
690 }
691 
692 static int mcp794xx_set_alarm(struct device *dev, struct rtc_wkalrm *t)
693 {
694 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
695 	unsigned char regs[10];
696 	int wday, ret;
697 
698 	if (!test_bit(HAS_ALARM, &ds1307->flags))
699 		return -EINVAL;
700 
701 	wday = mcp794xx_alm_weekday(dev, &t->time);
702 	if (wday < 0)
703 		return wday;
704 
705 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
706 		"enabled=%d pending=%d\n", __func__,
707 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
708 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
709 		t->enabled, t->pending);
710 
711 	/* Read control and alarm 0 registers. */
712 	ret = regmap_bulk_read(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
713 			       sizeof(regs));
714 	if (ret)
715 		return ret;
716 
717 	/* Set alarm 0, using 24-hour and day-of-month modes. */
718 	regs[3] = bin2bcd(t->time.tm_sec);
719 	regs[4] = bin2bcd(t->time.tm_min);
720 	regs[5] = bin2bcd(t->time.tm_hour);
721 	regs[6] = wday;
722 	regs[7] = bin2bcd(t->time.tm_mday);
723 	regs[8] = bin2bcd(t->time.tm_mon + 1);
724 
725 	/* Clear the alarm 0 interrupt flag. */
726 	regs[6] &= ~MCP794XX_BIT_ALMX_IF;
727 	/* Set alarm match: second, minute, hour, day, date, month. */
728 	regs[6] |= MCP794XX_MSK_ALMX_MATCH;
729 	/* Disable interrupt. We will not enable until completely programmed */
730 	regs[0] &= ~MCP794XX_BIT_ALM0_EN;
731 
732 	ret = regmap_bulk_write(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
733 				sizeof(regs));
734 	if (ret)
735 		return ret;
736 
737 	if (!t->enabled)
738 		return 0;
739 	regs[0] |= MCP794XX_BIT_ALM0_EN;
740 	return regmap_write(ds1307->regmap, MCP794XX_REG_CONTROL, regs[0]);
741 }
742 
743 static int mcp794xx_alarm_irq_enable(struct device *dev, unsigned int enabled)
744 {
745 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
746 
747 	if (!test_bit(HAS_ALARM, &ds1307->flags))
748 		return -EINVAL;
749 
750 	return regmap_update_bits(ds1307->regmap, MCP794XX_REG_CONTROL,
751 				  MCP794XX_BIT_ALM0_EN,
752 				  enabled ? MCP794XX_BIT_ALM0_EN : 0);
753 }
754 
755 static int m41txx_rtc_read_offset(struct device *dev, long *offset)
756 {
757 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
758 	unsigned int ctrl_reg;
759 	u8 val;
760 
761 	regmap_read(ds1307->regmap, M41TXX_REG_CONTROL, &ctrl_reg);
762 
763 	val = ctrl_reg & M41TXX_M_CALIBRATION;
764 
765 	/* check if positive */
766 	if (ctrl_reg & M41TXX_BIT_CALIB_SIGN)
767 		*offset = (val * M41TXX_POS_OFFSET_STEP_PPB);
768 	else
769 		*offset = -(val * M41TXX_NEG_OFFSET_STEP_PPB);
770 
771 	return 0;
772 }
773 
774 static int m41txx_rtc_set_offset(struct device *dev, long offset)
775 {
776 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
777 	unsigned int ctrl_reg;
778 
779 	if ((offset < M41TXX_MIN_OFFSET) || (offset > M41TXX_MAX_OFFSET))
780 		return -ERANGE;
781 
782 	if (offset >= 0) {
783 		ctrl_reg = DIV_ROUND_CLOSEST(offset,
784 					     M41TXX_POS_OFFSET_STEP_PPB);
785 		ctrl_reg |= M41TXX_BIT_CALIB_SIGN;
786 	} else {
787 		ctrl_reg = DIV_ROUND_CLOSEST(abs(offset),
788 					     M41TXX_NEG_OFFSET_STEP_PPB);
789 	}
790 
791 	return regmap_update_bits(ds1307->regmap, M41TXX_REG_CONTROL,
792 				  M41TXX_M_CALIBRATION | M41TXX_BIT_CALIB_SIGN,
793 				  ctrl_reg);
794 }
795 
796 static const struct rtc_class_ops rx8130_rtc_ops = {
797 	.read_time      = ds1307_get_time,
798 	.set_time       = ds1307_set_time,
799 	.read_alarm     = rx8130_read_alarm,
800 	.set_alarm      = rx8130_set_alarm,
801 	.alarm_irq_enable = rx8130_alarm_irq_enable,
802 };
803 
804 static const struct rtc_class_ops mcp794xx_rtc_ops = {
805 	.read_time      = ds1307_get_time,
806 	.set_time       = ds1307_set_time,
807 	.read_alarm     = mcp794xx_read_alarm,
808 	.set_alarm      = mcp794xx_set_alarm,
809 	.alarm_irq_enable = mcp794xx_alarm_irq_enable,
810 };
811 
812 static const struct rtc_class_ops m41txx_rtc_ops = {
813 	.read_time      = ds1307_get_time,
814 	.set_time       = ds1307_set_time,
815 	.read_alarm	= ds1337_read_alarm,
816 	.set_alarm	= ds1337_set_alarm,
817 	.alarm_irq_enable = ds1307_alarm_irq_enable,
818 	.read_offset	= m41txx_rtc_read_offset,
819 	.set_offset	= m41txx_rtc_set_offset,
820 };
821 
822 static const struct chip_desc chips[last_ds_type] = {
823 	[ds_1307] = {
824 		.nvram_offset	= 8,
825 		.nvram_size	= 56,
826 	},
827 	[ds_1308] = {
828 		.nvram_offset	= 8,
829 		.nvram_size	= 56,
830 	},
831 	[ds_1337] = {
832 		.alarm		= 1,
833 		.century_reg	= DS1307_REG_MONTH,
834 		.century_bit	= DS1337_BIT_CENTURY,
835 	},
836 	[ds_1338] = {
837 		.nvram_offset	= 8,
838 		.nvram_size	= 56,
839 	},
840 	[ds_1339] = {
841 		.alarm		= 1,
842 		.century_reg	= DS1307_REG_MONTH,
843 		.century_bit	= DS1337_BIT_CENTURY,
844 		.bbsqi_bit	= DS1339_BIT_BBSQI,
845 		.trickle_charger_reg = 0x10,
846 		.do_trickle_setup = &do_trickle_setup_ds1339,
847 	},
848 	[ds_1340] = {
849 		.century_reg	= DS1307_REG_HOUR,
850 		.century_enable_bit = DS1340_BIT_CENTURY_EN,
851 		.century_bit	= DS1340_BIT_CENTURY,
852 		.do_trickle_setup = &do_trickle_setup_ds1339,
853 		.trickle_charger_reg = 0x08,
854 	},
855 	[ds_1341] = {
856 		.century_reg	= DS1307_REG_MONTH,
857 		.century_bit	= DS1337_BIT_CENTURY,
858 	},
859 	[ds_1388] = {
860 		.offset		= 1,
861 		.trickle_charger_reg = 0x0a,
862 	},
863 	[ds_3231] = {
864 		.alarm		= 1,
865 		.century_reg	= DS1307_REG_MONTH,
866 		.century_bit	= DS1337_BIT_CENTURY,
867 		.bbsqi_bit	= DS3231_BIT_BBSQW,
868 	},
869 	[rx_8130] = {
870 		.alarm		= 1,
871 		/* this is battery backed SRAM */
872 		.nvram_offset	= 0x20,
873 		.nvram_size	= 4,	/* 32bit (4 word x 8 bit) */
874 		.offset		= 0x10,
875 		.irq_handler = rx8130_irq,
876 		.rtc_ops = &rx8130_rtc_ops,
877 	},
878 	[m41t0] = {
879 		.rtc_ops	= &m41txx_rtc_ops,
880 	},
881 	[m41t00] = {
882 		.rtc_ops	= &m41txx_rtc_ops,
883 	},
884 	[m41t11] = {
885 		/* this is battery backed SRAM */
886 		.nvram_offset	= 8,
887 		.nvram_size	= 56,
888 		.rtc_ops	= &m41txx_rtc_ops,
889 	},
890 	[mcp794xx] = {
891 		.alarm		= 1,
892 		/* this is battery backed SRAM */
893 		.nvram_offset	= 0x20,
894 		.nvram_size	= 0x40,
895 		.irq_handler = mcp794xx_irq,
896 		.rtc_ops = &mcp794xx_rtc_ops,
897 	},
898 };
899 
900 static const struct i2c_device_id ds1307_id[] = {
901 	{ "ds1307", ds_1307 },
902 	{ "ds1308", ds_1308 },
903 	{ "ds1337", ds_1337 },
904 	{ "ds1338", ds_1338 },
905 	{ "ds1339", ds_1339 },
906 	{ "ds1388", ds_1388 },
907 	{ "ds1340", ds_1340 },
908 	{ "ds1341", ds_1341 },
909 	{ "ds3231", ds_3231 },
910 	{ "m41t0", m41t0 },
911 	{ "m41t00", m41t00 },
912 	{ "m41t11", m41t11 },
913 	{ "mcp7940x", mcp794xx },
914 	{ "mcp7941x", mcp794xx },
915 	{ "pt7c4338", ds_1307 },
916 	{ "rx8025", rx_8025 },
917 	{ "isl12057", ds_1337 },
918 	{ "rx8130", rx_8130 },
919 	{ }
920 };
921 MODULE_DEVICE_TABLE(i2c, ds1307_id);
922 
923 #ifdef CONFIG_OF
924 static const struct of_device_id ds1307_of_match[] = {
925 	{
926 		.compatible = "dallas,ds1307",
927 		.data = (void *)ds_1307
928 	},
929 	{
930 		.compatible = "dallas,ds1308",
931 		.data = (void *)ds_1308
932 	},
933 	{
934 		.compatible = "dallas,ds1337",
935 		.data = (void *)ds_1337
936 	},
937 	{
938 		.compatible = "dallas,ds1338",
939 		.data = (void *)ds_1338
940 	},
941 	{
942 		.compatible = "dallas,ds1339",
943 		.data = (void *)ds_1339
944 	},
945 	{
946 		.compatible = "dallas,ds1388",
947 		.data = (void *)ds_1388
948 	},
949 	{
950 		.compatible = "dallas,ds1340",
951 		.data = (void *)ds_1340
952 	},
953 	{
954 		.compatible = "dallas,ds1341",
955 		.data = (void *)ds_1341
956 	},
957 	{
958 		.compatible = "maxim,ds3231",
959 		.data = (void *)ds_3231
960 	},
961 	{
962 		.compatible = "st,m41t0",
963 		.data = (void *)m41t0
964 	},
965 	{
966 		.compatible = "st,m41t00",
967 		.data = (void *)m41t00
968 	},
969 	{
970 		.compatible = "st,m41t11",
971 		.data = (void *)m41t11
972 	},
973 	{
974 		.compatible = "microchip,mcp7940x",
975 		.data = (void *)mcp794xx
976 	},
977 	{
978 		.compatible = "microchip,mcp7941x",
979 		.data = (void *)mcp794xx
980 	},
981 	{
982 		.compatible = "pericom,pt7c4338",
983 		.data = (void *)ds_1307
984 	},
985 	{
986 		.compatible = "epson,rx8025",
987 		.data = (void *)rx_8025
988 	},
989 	{
990 		.compatible = "isil,isl12057",
991 		.data = (void *)ds_1337
992 	},
993 	{
994 		.compatible = "epson,rx8130",
995 		.data = (void *)rx_8130
996 	},
997 	{ }
998 };
999 MODULE_DEVICE_TABLE(of, ds1307_of_match);
1000 #endif
1001 
1002 #ifdef CONFIG_ACPI
1003 static const struct acpi_device_id ds1307_acpi_ids[] = {
1004 	{ .id = "DS1307", .driver_data = ds_1307 },
1005 	{ .id = "DS1308", .driver_data = ds_1308 },
1006 	{ .id = "DS1337", .driver_data = ds_1337 },
1007 	{ .id = "DS1338", .driver_data = ds_1338 },
1008 	{ .id = "DS1339", .driver_data = ds_1339 },
1009 	{ .id = "DS1388", .driver_data = ds_1388 },
1010 	{ .id = "DS1340", .driver_data = ds_1340 },
1011 	{ .id = "DS1341", .driver_data = ds_1341 },
1012 	{ .id = "DS3231", .driver_data = ds_3231 },
1013 	{ .id = "M41T0", .driver_data = m41t0 },
1014 	{ .id = "M41T00", .driver_data = m41t00 },
1015 	{ .id = "M41T11", .driver_data = m41t11 },
1016 	{ .id = "MCP7940X", .driver_data = mcp794xx },
1017 	{ .id = "MCP7941X", .driver_data = mcp794xx },
1018 	{ .id = "PT7C4338", .driver_data = ds_1307 },
1019 	{ .id = "RX8025", .driver_data = rx_8025 },
1020 	{ .id = "ISL12057", .driver_data = ds_1337 },
1021 	{ .id = "RX8130", .driver_data = rx_8130 },
1022 	{ }
1023 };
1024 MODULE_DEVICE_TABLE(acpi, ds1307_acpi_ids);
1025 #endif
1026 
1027 /*
1028  * The ds1337 and ds1339 both have two alarms, but we only use the first
1029  * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
1030  * signal; ds1339 chips have only one alarm signal.
1031  */
1032 static irqreturn_t ds1307_irq(int irq, void *dev_id)
1033 {
1034 	struct ds1307		*ds1307 = dev_id;
1035 	struct mutex		*lock = &ds1307->rtc->ops_lock;
1036 	int			stat, ret;
1037 
1038 	mutex_lock(lock);
1039 	ret = regmap_read(ds1307->regmap, DS1337_REG_STATUS, &stat);
1040 	if (ret)
1041 		goto out;
1042 
1043 	if (stat & DS1337_BIT_A1I) {
1044 		stat &= ~DS1337_BIT_A1I;
1045 		regmap_write(ds1307->regmap, DS1337_REG_STATUS, stat);
1046 
1047 		ret = regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
1048 					 DS1337_BIT_A1IE, 0);
1049 		if (ret)
1050 			goto out;
1051 
1052 		rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
1053 	}
1054 
1055 out:
1056 	mutex_unlock(lock);
1057 
1058 	return IRQ_HANDLED;
1059 }
1060 
1061 /*----------------------------------------------------------------------*/
1062 
1063 static const struct rtc_class_ops ds13xx_rtc_ops = {
1064 	.read_time	= ds1307_get_time,
1065 	.set_time	= ds1307_set_time,
1066 	.read_alarm	= ds1337_read_alarm,
1067 	.set_alarm	= ds1337_set_alarm,
1068 	.alarm_irq_enable = ds1307_alarm_irq_enable,
1069 };
1070 
1071 static ssize_t frequency_test_store(struct device *dev,
1072 				    struct device_attribute *attr,
1073 				    const char *buf, size_t count)
1074 {
1075 	struct ds1307 *ds1307 = dev_get_drvdata(dev->parent);
1076 	bool freq_test_en;
1077 	int ret;
1078 
1079 	ret = kstrtobool(buf, &freq_test_en);
1080 	if (ret) {
1081 		dev_err(dev, "Failed to store RTC Frequency Test attribute\n");
1082 		return ret;
1083 	}
1084 
1085 	regmap_update_bits(ds1307->regmap, M41TXX_REG_CONTROL, M41TXX_BIT_FT,
1086 			   freq_test_en ? M41TXX_BIT_FT : 0);
1087 
1088 	return count;
1089 }
1090 
1091 static ssize_t frequency_test_show(struct device *dev,
1092 				   struct device_attribute *attr,
1093 				   char *buf)
1094 {
1095 	struct ds1307 *ds1307 = dev_get_drvdata(dev->parent);
1096 	unsigned int ctrl_reg;
1097 
1098 	regmap_read(ds1307->regmap, M41TXX_REG_CONTROL, &ctrl_reg);
1099 
1100 	return scnprintf(buf, PAGE_SIZE, (ctrl_reg & M41TXX_BIT_FT) ? "on\n" :
1101 			"off\n");
1102 }
1103 
1104 static DEVICE_ATTR_RW(frequency_test);
1105 
1106 static struct attribute *rtc_freq_test_attrs[] = {
1107 	&dev_attr_frequency_test.attr,
1108 	NULL,
1109 };
1110 
1111 static const struct attribute_group rtc_freq_test_attr_group = {
1112 	.attrs		= rtc_freq_test_attrs,
1113 };
1114 
1115 static int ds1307_add_frequency_test(struct ds1307 *ds1307)
1116 {
1117 	int err;
1118 
1119 	switch (ds1307->type) {
1120 	case m41t0:
1121 	case m41t00:
1122 	case m41t11:
1123 		err = rtc_add_group(ds1307->rtc, &rtc_freq_test_attr_group);
1124 		if (err)
1125 			return err;
1126 		break;
1127 	default:
1128 		break;
1129 	}
1130 
1131 	return 0;
1132 }
1133 
1134 /*----------------------------------------------------------------------*/
1135 
1136 static int ds1307_nvram_read(void *priv, unsigned int offset, void *val,
1137 			     size_t bytes)
1138 {
1139 	struct ds1307 *ds1307 = priv;
1140 	const struct chip_desc *chip = &chips[ds1307->type];
1141 
1142 	return regmap_bulk_read(ds1307->regmap, chip->nvram_offset + offset,
1143 				val, bytes);
1144 }
1145 
1146 static int ds1307_nvram_write(void *priv, unsigned int offset, void *val,
1147 			      size_t bytes)
1148 {
1149 	struct ds1307 *ds1307 = priv;
1150 	const struct chip_desc *chip = &chips[ds1307->type];
1151 
1152 	return regmap_bulk_write(ds1307->regmap, chip->nvram_offset + offset,
1153 				 val, bytes);
1154 }
1155 
1156 /*----------------------------------------------------------------------*/
1157 
1158 static u8 ds1307_trickle_init(struct ds1307 *ds1307,
1159 			      const struct chip_desc *chip)
1160 {
1161 	u32 ohms;
1162 	bool diode = true;
1163 
1164 	if (!chip->do_trickle_setup)
1165 		return 0;
1166 
1167 	if (device_property_read_u32(ds1307->dev, "trickle-resistor-ohms",
1168 				     &ohms))
1169 		return 0;
1170 
1171 	if (device_property_read_bool(ds1307->dev, "trickle-diode-disable"))
1172 		diode = false;
1173 
1174 	return chip->do_trickle_setup(ds1307, ohms, diode);
1175 }
1176 
1177 /*----------------------------------------------------------------------*/
1178 
1179 #if IS_REACHABLE(CONFIG_HWMON)
1180 
1181 /*
1182  * Temperature sensor support for ds3231 devices.
1183  */
1184 
1185 #define DS3231_REG_TEMPERATURE	0x11
1186 
1187 /*
1188  * A user-initiated temperature conversion is not started by this function,
1189  * so the temperature is updated once every 64 seconds.
1190  */
1191 static int ds3231_hwmon_read_temp(struct device *dev, s32 *mC)
1192 {
1193 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
1194 	u8 temp_buf[2];
1195 	s16 temp;
1196 	int ret;
1197 
1198 	ret = regmap_bulk_read(ds1307->regmap, DS3231_REG_TEMPERATURE,
1199 			       temp_buf, sizeof(temp_buf));
1200 	if (ret)
1201 		return ret;
1202 	/*
1203 	 * Temperature is represented as a 10-bit code with a resolution of
1204 	 * 0.25 degree celsius and encoded in two's complement format.
1205 	 */
1206 	temp = (temp_buf[0] << 8) | temp_buf[1];
1207 	temp >>= 6;
1208 	*mC = temp * 250;
1209 
1210 	return 0;
1211 }
1212 
1213 static ssize_t ds3231_hwmon_show_temp(struct device *dev,
1214 				      struct device_attribute *attr, char *buf)
1215 {
1216 	int ret;
1217 	s32 temp;
1218 
1219 	ret = ds3231_hwmon_read_temp(dev, &temp);
1220 	if (ret)
1221 		return ret;
1222 
1223 	return sprintf(buf, "%d\n", temp);
1224 }
1225 static SENSOR_DEVICE_ATTR(temp1_input, 0444, ds3231_hwmon_show_temp,
1226 			  NULL, 0);
1227 
1228 static struct attribute *ds3231_hwmon_attrs[] = {
1229 	&sensor_dev_attr_temp1_input.dev_attr.attr,
1230 	NULL,
1231 };
1232 ATTRIBUTE_GROUPS(ds3231_hwmon);
1233 
1234 static void ds1307_hwmon_register(struct ds1307 *ds1307)
1235 {
1236 	struct device *dev;
1237 
1238 	if (ds1307->type != ds_3231)
1239 		return;
1240 
1241 	dev = devm_hwmon_device_register_with_groups(ds1307->dev, ds1307->name,
1242 						     ds1307,
1243 						     ds3231_hwmon_groups);
1244 	if (IS_ERR(dev)) {
1245 		dev_warn(ds1307->dev, "unable to register hwmon device %ld\n",
1246 			 PTR_ERR(dev));
1247 	}
1248 }
1249 
1250 #else
1251 
1252 static void ds1307_hwmon_register(struct ds1307 *ds1307)
1253 {
1254 }
1255 
1256 #endif /* CONFIG_RTC_DRV_DS1307_HWMON */
1257 
1258 /*----------------------------------------------------------------------*/
1259 
1260 /*
1261  * Square-wave output support for DS3231
1262  * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS3231.pdf
1263  */
1264 #ifdef CONFIG_COMMON_CLK
1265 
1266 enum {
1267 	DS3231_CLK_SQW = 0,
1268 	DS3231_CLK_32KHZ,
1269 };
1270 
1271 #define clk_sqw_to_ds1307(clk)	\
1272 	container_of(clk, struct ds1307, clks[DS3231_CLK_SQW])
1273 #define clk_32khz_to_ds1307(clk)	\
1274 	container_of(clk, struct ds1307, clks[DS3231_CLK_32KHZ])
1275 
1276 static int ds3231_clk_sqw_rates[] = {
1277 	1,
1278 	1024,
1279 	4096,
1280 	8192,
1281 };
1282 
1283 static int ds1337_write_control(struct ds1307 *ds1307, u8 mask, u8 value)
1284 {
1285 	struct mutex *lock = &ds1307->rtc->ops_lock;
1286 	int ret;
1287 
1288 	mutex_lock(lock);
1289 	ret = regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
1290 				 mask, value);
1291 	mutex_unlock(lock);
1292 
1293 	return ret;
1294 }
1295 
1296 static unsigned long ds3231_clk_sqw_recalc_rate(struct clk_hw *hw,
1297 						unsigned long parent_rate)
1298 {
1299 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1300 	int control, ret;
1301 	int rate_sel = 0;
1302 
1303 	ret = regmap_read(ds1307->regmap, DS1337_REG_CONTROL, &control);
1304 	if (ret)
1305 		return ret;
1306 	if (control & DS1337_BIT_RS1)
1307 		rate_sel += 1;
1308 	if (control & DS1337_BIT_RS2)
1309 		rate_sel += 2;
1310 
1311 	return ds3231_clk_sqw_rates[rate_sel];
1312 }
1313 
1314 static long ds3231_clk_sqw_round_rate(struct clk_hw *hw, unsigned long rate,
1315 				      unsigned long *prate)
1316 {
1317 	int i;
1318 
1319 	for (i = ARRAY_SIZE(ds3231_clk_sqw_rates) - 1; i >= 0; i--) {
1320 		if (ds3231_clk_sqw_rates[i] <= rate)
1321 			return ds3231_clk_sqw_rates[i];
1322 	}
1323 
1324 	return 0;
1325 }
1326 
1327 static int ds3231_clk_sqw_set_rate(struct clk_hw *hw, unsigned long rate,
1328 				   unsigned long parent_rate)
1329 {
1330 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1331 	int control = 0;
1332 	int rate_sel;
1333 
1334 	for (rate_sel = 0; rate_sel < ARRAY_SIZE(ds3231_clk_sqw_rates);
1335 			rate_sel++) {
1336 		if (ds3231_clk_sqw_rates[rate_sel] == rate)
1337 			break;
1338 	}
1339 
1340 	if (rate_sel == ARRAY_SIZE(ds3231_clk_sqw_rates))
1341 		return -EINVAL;
1342 
1343 	if (rate_sel & 1)
1344 		control |= DS1337_BIT_RS1;
1345 	if (rate_sel & 2)
1346 		control |= DS1337_BIT_RS2;
1347 
1348 	return ds1337_write_control(ds1307, DS1337_BIT_RS1 | DS1337_BIT_RS2,
1349 				control);
1350 }
1351 
1352 static int ds3231_clk_sqw_prepare(struct clk_hw *hw)
1353 {
1354 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1355 
1356 	return ds1337_write_control(ds1307, DS1337_BIT_INTCN, 0);
1357 }
1358 
1359 static void ds3231_clk_sqw_unprepare(struct clk_hw *hw)
1360 {
1361 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1362 
1363 	ds1337_write_control(ds1307, DS1337_BIT_INTCN, DS1337_BIT_INTCN);
1364 }
1365 
1366 static int ds3231_clk_sqw_is_prepared(struct clk_hw *hw)
1367 {
1368 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1369 	int control, ret;
1370 
1371 	ret = regmap_read(ds1307->regmap, DS1337_REG_CONTROL, &control);
1372 	if (ret)
1373 		return ret;
1374 
1375 	return !(control & DS1337_BIT_INTCN);
1376 }
1377 
1378 static const struct clk_ops ds3231_clk_sqw_ops = {
1379 	.prepare = ds3231_clk_sqw_prepare,
1380 	.unprepare = ds3231_clk_sqw_unprepare,
1381 	.is_prepared = ds3231_clk_sqw_is_prepared,
1382 	.recalc_rate = ds3231_clk_sqw_recalc_rate,
1383 	.round_rate = ds3231_clk_sqw_round_rate,
1384 	.set_rate = ds3231_clk_sqw_set_rate,
1385 };
1386 
1387 static unsigned long ds3231_clk_32khz_recalc_rate(struct clk_hw *hw,
1388 						  unsigned long parent_rate)
1389 {
1390 	return 32768;
1391 }
1392 
1393 static int ds3231_clk_32khz_control(struct ds1307 *ds1307, bool enable)
1394 {
1395 	struct mutex *lock = &ds1307->rtc->ops_lock;
1396 	int ret;
1397 
1398 	mutex_lock(lock);
1399 	ret = regmap_update_bits(ds1307->regmap, DS1337_REG_STATUS,
1400 				 DS3231_BIT_EN32KHZ,
1401 				 enable ? DS3231_BIT_EN32KHZ : 0);
1402 	mutex_unlock(lock);
1403 
1404 	return ret;
1405 }
1406 
1407 static int ds3231_clk_32khz_prepare(struct clk_hw *hw)
1408 {
1409 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1410 
1411 	return ds3231_clk_32khz_control(ds1307, true);
1412 }
1413 
1414 static void ds3231_clk_32khz_unprepare(struct clk_hw *hw)
1415 {
1416 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1417 
1418 	ds3231_clk_32khz_control(ds1307, false);
1419 }
1420 
1421 static int ds3231_clk_32khz_is_prepared(struct clk_hw *hw)
1422 {
1423 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1424 	int status, ret;
1425 
1426 	ret = regmap_read(ds1307->regmap, DS1337_REG_STATUS, &status);
1427 	if (ret)
1428 		return ret;
1429 
1430 	return !!(status & DS3231_BIT_EN32KHZ);
1431 }
1432 
1433 static const struct clk_ops ds3231_clk_32khz_ops = {
1434 	.prepare = ds3231_clk_32khz_prepare,
1435 	.unprepare = ds3231_clk_32khz_unprepare,
1436 	.is_prepared = ds3231_clk_32khz_is_prepared,
1437 	.recalc_rate = ds3231_clk_32khz_recalc_rate,
1438 };
1439 
1440 static struct clk_init_data ds3231_clks_init[] = {
1441 	[DS3231_CLK_SQW] = {
1442 		.name = "ds3231_clk_sqw",
1443 		.ops = &ds3231_clk_sqw_ops,
1444 	},
1445 	[DS3231_CLK_32KHZ] = {
1446 		.name = "ds3231_clk_32khz",
1447 		.ops = &ds3231_clk_32khz_ops,
1448 	},
1449 };
1450 
1451 static int ds3231_clks_register(struct ds1307 *ds1307)
1452 {
1453 	struct device_node *node = ds1307->dev->of_node;
1454 	struct clk_onecell_data	*onecell;
1455 	int i;
1456 
1457 	onecell = devm_kzalloc(ds1307->dev, sizeof(*onecell), GFP_KERNEL);
1458 	if (!onecell)
1459 		return -ENOMEM;
1460 
1461 	onecell->clk_num = ARRAY_SIZE(ds3231_clks_init);
1462 	onecell->clks = devm_kcalloc(ds1307->dev, onecell->clk_num,
1463 				     sizeof(onecell->clks[0]), GFP_KERNEL);
1464 	if (!onecell->clks)
1465 		return -ENOMEM;
1466 
1467 	for (i = 0; i < ARRAY_SIZE(ds3231_clks_init); i++) {
1468 		struct clk_init_data init = ds3231_clks_init[i];
1469 
1470 		/*
1471 		 * Interrupt signal due to alarm conditions and square-wave
1472 		 * output share same pin, so don't initialize both.
1473 		 */
1474 		if (i == DS3231_CLK_SQW && test_bit(HAS_ALARM, &ds1307->flags))
1475 			continue;
1476 
1477 		/* optional override of the clockname */
1478 		of_property_read_string_index(node, "clock-output-names", i,
1479 					      &init.name);
1480 		ds1307->clks[i].init = &init;
1481 
1482 		onecell->clks[i] = devm_clk_register(ds1307->dev,
1483 						     &ds1307->clks[i]);
1484 		if (IS_ERR(onecell->clks[i]))
1485 			return PTR_ERR(onecell->clks[i]);
1486 	}
1487 
1488 	if (!node)
1489 		return 0;
1490 
1491 	of_clk_add_provider(node, of_clk_src_onecell_get, onecell);
1492 
1493 	return 0;
1494 }
1495 
1496 static void ds1307_clks_register(struct ds1307 *ds1307)
1497 {
1498 	int ret;
1499 
1500 	if (ds1307->type != ds_3231)
1501 		return;
1502 
1503 	ret = ds3231_clks_register(ds1307);
1504 	if (ret) {
1505 		dev_warn(ds1307->dev, "unable to register clock device %d\n",
1506 			 ret);
1507 	}
1508 }
1509 
1510 #else
1511 
1512 static void ds1307_clks_register(struct ds1307 *ds1307)
1513 {
1514 }
1515 
1516 #endif /* CONFIG_COMMON_CLK */
1517 
1518 static const struct regmap_config regmap_config = {
1519 	.reg_bits = 8,
1520 	.val_bits = 8,
1521 };
1522 
1523 static int ds1307_probe(struct i2c_client *client,
1524 			const struct i2c_device_id *id)
1525 {
1526 	struct ds1307		*ds1307;
1527 	int			err = -ENODEV;
1528 	int			tmp;
1529 	const struct chip_desc	*chip;
1530 	bool			want_irq;
1531 	bool			ds1307_can_wakeup_device = false;
1532 	unsigned char		regs[8];
1533 	struct ds1307_platform_data *pdata = dev_get_platdata(&client->dev);
1534 	u8			trickle_charger_setup = 0;
1535 
1536 	ds1307 = devm_kzalloc(&client->dev, sizeof(struct ds1307), GFP_KERNEL);
1537 	if (!ds1307)
1538 		return -ENOMEM;
1539 
1540 	dev_set_drvdata(&client->dev, ds1307);
1541 	ds1307->dev = &client->dev;
1542 	ds1307->name = client->name;
1543 
1544 	ds1307->regmap = devm_regmap_init_i2c(client, &regmap_config);
1545 	if (IS_ERR(ds1307->regmap)) {
1546 		dev_err(ds1307->dev, "regmap allocation failed\n");
1547 		return PTR_ERR(ds1307->regmap);
1548 	}
1549 
1550 	i2c_set_clientdata(client, ds1307);
1551 
1552 	if (client->dev.of_node) {
1553 		ds1307->type = (enum ds_type)
1554 			of_device_get_match_data(&client->dev);
1555 		chip = &chips[ds1307->type];
1556 	} else if (id) {
1557 		chip = &chips[id->driver_data];
1558 		ds1307->type = id->driver_data;
1559 	} else {
1560 		const struct acpi_device_id *acpi_id;
1561 
1562 		acpi_id = acpi_match_device(ACPI_PTR(ds1307_acpi_ids),
1563 					    ds1307->dev);
1564 		if (!acpi_id)
1565 			return -ENODEV;
1566 		chip = &chips[acpi_id->driver_data];
1567 		ds1307->type = acpi_id->driver_data;
1568 	}
1569 
1570 	want_irq = client->irq > 0 && chip->alarm;
1571 
1572 	if (!pdata)
1573 		trickle_charger_setup = ds1307_trickle_init(ds1307, chip);
1574 	else if (pdata->trickle_charger_setup)
1575 		trickle_charger_setup = pdata->trickle_charger_setup;
1576 
1577 	if (trickle_charger_setup && chip->trickle_charger_reg) {
1578 		trickle_charger_setup |= DS13XX_TRICKLE_CHARGER_MAGIC;
1579 		dev_dbg(ds1307->dev,
1580 			"writing trickle charger info 0x%x to 0x%x\n",
1581 			trickle_charger_setup, chip->trickle_charger_reg);
1582 		regmap_write(ds1307->regmap, chip->trickle_charger_reg,
1583 			     trickle_charger_setup);
1584 	}
1585 
1586 #ifdef CONFIG_OF
1587 /*
1588  * For devices with no IRQ directly connected to the SoC, the RTC chip
1589  * can be forced as a wakeup source by stating that explicitly in
1590  * the device's .dts file using the "wakeup-source" boolean property.
1591  * If the "wakeup-source" property is set, don't request an IRQ.
1592  * This will guarantee the 'wakealarm' sysfs entry is available on the device,
1593  * if supported by the RTC.
1594  */
1595 	if (chip->alarm && of_property_read_bool(client->dev.of_node,
1596 						 "wakeup-source"))
1597 		ds1307_can_wakeup_device = true;
1598 #endif
1599 
1600 	switch (ds1307->type) {
1601 	case ds_1337:
1602 	case ds_1339:
1603 	case ds_1341:
1604 	case ds_3231:
1605 		/* get registers that the "rtc" read below won't read... */
1606 		err = regmap_bulk_read(ds1307->regmap, DS1337_REG_CONTROL,
1607 				       regs, 2);
1608 		if (err) {
1609 			dev_dbg(ds1307->dev, "read error %d\n", err);
1610 			goto exit;
1611 		}
1612 
1613 		/* oscillator off?  turn it on, so clock can tick. */
1614 		if (regs[0] & DS1337_BIT_nEOSC)
1615 			regs[0] &= ~DS1337_BIT_nEOSC;
1616 
1617 		/*
1618 		 * Using IRQ or defined as wakeup-source?
1619 		 * Disable the square wave and both alarms.
1620 		 * For some variants, be sure alarms can trigger when we're
1621 		 * running on Vbackup (BBSQI/BBSQW)
1622 		 */
1623 		if (want_irq || ds1307_can_wakeup_device) {
1624 			regs[0] |= DS1337_BIT_INTCN | chip->bbsqi_bit;
1625 			regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
1626 		}
1627 
1628 		regmap_write(ds1307->regmap, DS1337_REG_CONTROL,
1629 			     regs[0]);
1630 
1631 		/* oscillator fault?  clear flag, and warn */
1632 		if (regs[1] & DS1337_BIT_OSF) {
1633 			regmap_write(ds1307->regmap, DS1337_REG_STATUS,
1634 				     regs[1] & ~DS1337_BIT_OSF);
1635 			dev_warn(ds1307->dev, "SET TIME!\n");
1636 		}
1637 		break;
1638 
1639 	case rx_8025:
1640 		err = regmap_bulk_read(ds1307->regmap,
1641 				       RX8025_REG_CTRL1 << 4 | 0x08, regs, 2);
1642 		if (err) {
1643 			dev_dbg(ds1307->dev, "read error %d\n", err);
1644 			goto exit;
1645 		}
1646 
1647 		/* oscillator off?  turn it on, so clock can tick. */
1648 		if (!(regs[1] & RX8025_BIT_XST)) {
1649 			regs[1] |= RX8025_BIT_XST;
1650 			regmap_write(ds1307->regmap,
1651 				     RX8025_REG_CTRL2 << 4 | 0x08,
1652 				     regs[1]);
1653 			dev_warn(ds1307->dev,
1654 				 "oscillator stop detected - SET TIME!\n");
1655 		}
1656 
1657 		if (regs[1] & RX8025_BIT_PON) {
1658 			regs[1] &= ~RX8025_BIT_PON;
1659 			regmap_write(ds1307->regmap,
1660 				     RX8025_REG_CTRL2 << 4 | 0x08,
1661 				     regs[1]);
1662 			dev_warn(ds1307->dev, "power-on detected\n");
1663 		}
1664 
1665 		if (regs[1] & RX8025_BIT_VDET) {
1666 			regs[1] &= ~RX8025_BIT_VDET;
1667 			regmap_write(ds1307->regmap,
1668 				     RX8025_REG_CTRL2 << 4 | 0x08,
1669 				     regs[1]);
1670 			dev_warn(ds1307->dev, "voltage drop detected\n");
1671 		}
1672 
1673 		/* make sure we are running in 24hour mode */
1674 		if (!(regs[0] & RX8025_BIT_2412)) {
1675 			u8 hour;
1676 
1677 			/* switch to 24 hour mode */
1678 			regmap_write(ds1307->regmap,
1679 				     RX8025_REG_CTRL1 << 4 | 0x08,
1680 				     regs[0] | RX8025_BIT_2412);
1681 
1682 			err = regmap_bulk_read(ds1307->regmap,
1683 					       RX8025_REG_CTRL1 << 4 | 0x08,
1684 					       regs, 2);
1685 			if (err) {
1686 				dev_dbg(ds1307->dev, "read error %d\n", err);
1687 				goto exit;
1688 			}
1689 
1690 			/* correct hour */
1691 			hour = bcd2bin(regs[DS1307_REG_HOUR]);
1692 			if (hour == 12)
1693 				hour = 0;
1694 			if (regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1695 				hour += 12;
1696 
1697 			regmap_write(ds1307->regmap,
1698 				     DS1307_REG_HOUR << 4 | 0x08, hour);
1699 		}
1700 		break;
1701 	default:
1702 		break;
1703 	}
1704 
1705 read_rtc:
1706 	/* read RTC registers */
1707 	err = regmap_bulk_read(ds1307->regmap, chip->offset, regs,
1708 			       sizeof(regs));
1709 	if (err) {
1710 		dev_dbg(ds1307->dev, "read error %d\n", err);
1711 		goto exit;
1712 	}
1713 
1714 	/*
1715 	 * minimal sanity checking; some chips (like DS1340) don't
1716 	 * specify the extra bits as must-be-zero, but there are
1717 	 * still a few values that are clearly out-of-range.
1718 	 */
1719 	tmp = regs[DS1307_REG_SECS];
1720 	switch (ds1307->type) {
1721 	case ds_1307:
1722 	case m41t0:
1723 	case m41t00:
1724 	case m41t11:
1725 		/* clock halted?  turn it on, so clock can tick. */
1726 		if (tmp & DS1307_BIT_CH) {
1727 			regmap_write(ds1307->regmap, DS1307_REG_SECS, 0);
1728 			dev_warn(ds1307->dev, "SET TIME!\n");
1729 			goto read_rtc;
1730 		}
1731 		break;
1732 	case ds_1308:
1733 	case ds_1338:
1734 		/* clock halted?  turn it on, so clock can tick. */
1735 		if (tmp & DS1307_BIT_CH)
1736 			regmap_write(ds1307->regmap, DS1307_REG_SECS, 0);
1737 
1738 		/* oscillator fault?  clear flag, and warn */
1739 		if (regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
1740 			regmap_write(ds1307->regmap, DS1307_REG_CONTROL,
1741 				     regs[DS1307_REG_CONTROL] &
1742 				     ~DS1338_BIT_OSF);
1743 			dev_warn(ds1307->dev, "SET TIME!\n");
1744 			goto read_rtc;
1745 		}
1746 		break;
1747 	case ds_1340:
1748 		/* clock halted?  turn it on, so clock can tick. */
1749 		if (tmp & DS1340_BIT_nEOSC)
1750 			regmap_write(ds1307->regmap, DS1307_REG_SECS, 0);
1751 
1752 		err = regmap_read(ds1307->regmap, DS1340_REG_FLAG, &tmp);
1753 		if (err) {
1754 			dev_dbg(ds1307->dev, "read error %d\n", err);
1755 			goto exit;
1756 		}
1757 
1758 		/* oscillator fault?  clear flag, and warn */
1759 		if (tmp & DS1340_BIT_OSF) {
1760 			regmap_write(ds1307->regmap, DS1340_REG_FLAG, 0);
1761 			dev_warn(ds1307->dev, "SET TIME!\n");
1762 		}
1763 		break;
1764 	case mcp794xx:
1765 		/* make sure that the backup battery is enabled */
1766 		if (!(regs[DS1307_REG_WDAY] & MCP794XX_BIT_VBATEN)) {
1767 			regmap_write(ds1307->regmap, DS1307_REG_WDAY,
1768 				     regs[DS1307_REG_WDAY] |
1769 				     MCP794XX_BIT_VBATEN);
1770 		}
1771 
1772 		/* clock halted?  turn it on, so clock can tick. */
1773 		if (!(tmp & MCP794XX_BIT_ST)) {
1774 			regmap_write(ds1307->regmap, DS1307_REG_SECS,
1775 				     MCP794XX_BIT_ST);
1776 			dev_warn(ds1307->dev, "SET TIME!\n");
1777 			goto read_rtc;
1778 		}
1779 
1780 		break;
1781 	default:
1782 		break;
1783 	}
1784 
1785 	tmp = regs[DS1307_REG_HOUR];
1786 	switch (ds1307->type) {
1787 	case ds_1340:
1788 	case m41t0:
1789 	case m41t00:
1790 	case m41t11:
1791 		/*
1792 		 * NOTE: ignores century bits; fix before deploying
1793 		 * systems that will run through year 2100.
1794 		 */
1795 		break;
1796 	case rx_8025:
1797 		break;
1798 	default:
1799 		if (!(tmp & DS1307_BIT_12HR))
1800 			break;
1801 
1802 		/*
1803 		 * Be sure we're in 24 hour mode.  Multi-master systems
1804 		 * take note...
1805 		 */
1806 		tmp = bcd2bin(tmp & 0x1f);
1807 		if (tmp == 12)
1808 			tmp = 0;
1809 		if (regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1810 			tmp += 12;
1811 		regmap_write(ds1307->regmap, chip->offset + DS1307_REG_HOUR,
1812 			     bin2bcd(tmp));
1813 	}
1814 
1815 	if (want_irq || ds1307_can_wakeup_device) {
1816 		device_set_wakeup_capable(ds1307->dev, true);
1817 		set_bit(HAS_ALARM, &ds1307->flags);
1818 	}
1819 
1820 	ds1307->rtc = devm_rtc_allocate_device(ds1307->dev);
1821 	if (IS_ERR(ds1307->rtc))
1822 		return PTR_ERR(ds1307->rtc);
1823 
1824 	if (ds1307_can_wakeup_device && !want_irq) {
1825 		dev_info(ds1307->dev,
1826 			 "'wakeup-source' is set, request for an IRQ is disabled!\n");
1827 		/* We cannot support UIE mode if we do not have an IRQ line */
1828 		ds1307->rtc->uie_unsupported = 1;
1829 	}
1830 
1831 	if (want_irq) {
1832 		err = devm_request_threaded_irq(ds1307->dev, client->irq, NULL,
1833 						chip->irq_handler ?: ds1307_irq,
1834 						IRQF_SHARED | IRQF_ONESHOT,
1835 						ds1307->name, ds1307);
1836 		if (err) {
1837 			client->irq = 0;
1838 			device_set_wakeup_capable(ds1307->dev, false);
1839 			clear_bit(HAS_ALARM, &ds1307->flags);
1840 			dev_err(ds1307->dev, "unable to request IRQ!\n");
1841 		} else {
1842 			dev_dbg(ds1307->dev, "got IRQ %d\n", client->irq);
1843 		}
1844 	}
1845 
1846 	ds1307->rtc->ops = chip->rtc_ops ?: &ds13xx_rtc_ops;
1847 	err = ds1307_add_frequency_test(ds1307);
1848 	if (err)
1849 		return err;
1850 
1851 	err = rtc_register_device(ds1307->rtc);
1852 	if (err)
1853 		return err;
1854 
1855 	if (chip->nvram_size) {
1856 		struct nvmem_config nvmem_cfg = {
1857 			.name = "ds1307_nvram",
1858 			.word_size = 1,
1859 			.stride = 1,
1860 			.size = chip->nvram_size,
1861 			.reg_read = ds1307_nvram_read,
1862 			.reg_write = ds1307_nvram_write,
1863 			.priv = ds1307,
1864 		};
1865 
1866 		ds1307->rtc->nvram_old_abi = true;
1867 		rtc_nvmem_register(ds1307->rtc, &nvmem_cfg);
1868 	}
1869 
1870 	ds1307_hwmon_register(ds1307);
1871 	ds1307_clks_register(ds1307);
1872 
1873 	return 0;
1874 
1875 exit:
1876 	return err;
1877 }
1878 
1879 static struct i2c_driver ds1307_driver = {
1880 	.driver = {
1881 		.name	= "rtc-ds1307",
1882 		.of_match_table = of_match_ptr(ds1307_of_match),
1883 		.acpi_match_table = ACPI_PTR(ds1307_acpi_ids),
1884 	},
1885 	.probe		= ds1307_probe,
1886 	.id_table	= ds1307_id,
1887 };
1888 
1889 module_i2c_driver(ds1307_driver);
1890 
1891 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
1892 MODULE_LICENSE("GPL");
1893