xref: /linux/drivers/rtc/rtc-ds1307.c (revision 995832b2cebe6969d1b42635db698803ee31294d)
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/bcd.h>
12 #include <linux/i2c.h>
13 #include <linux/init.h>
14 #include <linux/kstrtox.h>
15 #include <linux/module.h>
16 #include <linux/property.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 	unknown_ds_type, /* always first and 0 */
35 	ds_1307,
36 	ds_1308,
37 	ds_1337,
38 	ds_1338,
39 	ds_1339,
40 	ds_1340,
41 	ds_1341,
42 	ds_1388,
43 	ds_3231,
44 	m41t0,
45 	m41t00,
46 	m41t11,
47 	mcp794xx,
48 	rx_8025,
49 	rx_8130,
50 	last_ds_type /* always last */
51 	/* rs5c372 too?  different address... */
52 };
53 
54 /* RTC registers don't differ much, except for the century flag */
55 #define DS1307_REG_SECS		0x00	/* 00-59 */
56 #	define DS1307_BIT_CH		0x80
57 #	define DS1340_BIT_nEOSC		0x80
58 #	define MCP794XX_BIT_ST		0x80
59 #define DS1307_REG_MIN		0x01	/* 00-59 */
60 #	define M41T0_BIT_OF		0x80
61 #define DS1307_REG_HOUR		0x02	/* 00-23, or 1-12{am,pm} */
62 #	define DS1307_BIT_12HR		0x40	/* in REG_HOUR */
63 #	define DS1307_BIT_PM		0x20	/* in REG_HOUR */
64 #	define DS1340_BIT_CENTURY_EN	0x80	/* in REG_HOUR */
65 #	define DS1340_BIT_CENTURY	0x40	/* in REG_HOUR */
66 #define DS1307_REG_WDAY		0x03	/* 01-07 */
67 #	define MCP794XX_BIT_OSCRUN	BIT(5)
68 #	define MCP794XX_BIT_VBATEN	0x08
69 #define DS1307_REG_MDAY		0x04	/* 01-31 */
70 #define DS1307_REG_MONTH	0x05	/* 01-12 */
71 #	define DS1337_BIT_CENTURY	0x80	/* in REG_MONTH */
72 #define DS1307_REG_YEAR		0x06	/* 00-99 */
73 
74 /*
75  * Other registers (control, status, alarms, trickle charge, NVRAM, etc)
76  * start at 7, and they differ a LOT. Only control and status matter for
77  * basic RTC date and time functionality; be careful using them.
78  */
79 #define DS1307_REG_CONTROL	0x07		/* or ds1338 */
80 #	define DS1307_BIT_OUT		0x80
81 #	define DS1338_BIT_OSF		0x20
82 #	define DS1307_BIT_SQWE		0x10
83 #	define DS1307_BIT_RS1		0x02
84 #	define DS1307_BIT_RS0		0x01
85 #define DS1337_REG_CONTROL	0x0e
86 #	define DS1337_BIT_nEOSC		0x80
87 #	define DS1339_BIT_BBSQI		0x20
88 #	define DS3231_BIT_BBSQW		0x40 /* same as BBSQI */
89 #	define DS1337_BIT_RS2		0x10
90 #	define DS1337_BIT_RS1		0x08
91 #	define DS1337_BIT_INTCN		0x04
92 #	define DS1337_BIT_A2IE		0x02
93 #	define DS1337_BIT_A1IE		0x01
94 #define DS1340_REG_CONTROL	0x07
95 #	define DS1340_BIT_OUT		0x80
96 #	define DS1340_BIT_FT		0x40
97 #	define DS1340_BIT_CALIB_SIGN	0x20
98 #	define DS1340_M_CALIBRATION	0x1f
99 #define DS1340_REG_FLAG		0x09
100 #	define DS1340_BIT_OSF		0x80
101 #define DS1337_REG_STATUS	0x0f
102 #	define DS1337_BIT_OSF		0x80
103 #	define DS3231_BIT_EN32KHZ	0x08
104 #	define DS1337_BIT_A2I		0x02
105 #	define DS1337_BIT_A1I		0x01
106 #define DS1339_REG_ALARM1_SECS	0x07
107 
108 #define DS13XX_TRICKLE_CHARGER_MAGIC	0xa0
109 
110 #define RX8025_REG_CTRL1	0x0e
111 #	define RX8025_BIT_2412		0x20
112 #define RX8025_REG_CTRL2	0x0f
113 #	define RX8025_BIT_PON		0x10
114 #	define RX8025_BIT_VDET		0x40
115 #	define RX8025_BIT_XST		0x20
116 
117 #define RX8130_REG_ALARM_MIN		0x17
118 #define RX8130_REG_ALARM_HOUR		0x18
119 #define RX8130_REG_ALARM_WEEK_OR_DAY	0x19
120 #define RX8130_REG_EXTENSION		0x1c
121 #define RX8130_REG_EXTENSION_WADA	BIT(3)
122 #define RX8130_REG_FLAG			0x1d
123 #define RX8130_REG_FLAG_VLF		BIT(1)
124 #define RX8130_REG_FLAG_AF		BIT(3)
125 #define RX8130_REG_CONTROL0		0x1e
126 #define RX8130_REG_CONTROL0_AIE		BIT(3)
127 #define RX8130_REG_CONTROL1		0x1f
128 #define RX8130_REG_CONTROL1_INIEN	BIT(4)
129 #define RX8130_REG_CONTROL1_CHGEN	BIT(5)
130 
131 #define MCP794XX_REG_CONTROL		0x07
132 #	define MCP794XX_BIT_ALM0_EN	0x10
133 #	define MCP794XX_BIT_ALM1_EN	0x20
134 #define MCP794XX_REG_ALARM0_BASE	0x0a
135 #define MCP794XX_REG_ALARM0_CTRL	0x0d
136 #define MCP794XX_REG_ALARM1_BASE	0x11
137 #define MCP794XX_REG_ALARM1_CTRL	0x14
138 #	define MCP794XX_BIT_ALMX_IF	BIT(3)
139 #	define MCP794XX_BIT_ALMX_C0	BIT(4)
140 #	define MCP794XX_BIT_ALMX_C1	BIT(5)
141 #	define MCP794XX_BIT_ALMX_C2	BIT(6)
142 #	define MCP794XX_BIT_ALMX_POL	BIT(7)
143 #	define MCP794XX_MSK_ALMX_MATCH	(MCP794XX_BIT_ALMX_C0 | \
144 					 MCP794XX_BIT_ALMX_C1 | \
145 					 MCP794XX_BIT_ALMX_C2)
146 
147 #define M41TXX_REG_CONTROL	0x07
148 #	define M41TXX_BIT_OUT		BIT(7)
149 #	define M41TXX_BIT_FT		BIT(6)
150 #	define M41TXX_BIT_CALIB_SIGN	BIT(5)
151 #	define M41TXX_M_CALIBRATION	GENMASK(4, 0)
152 
153 #define DS1388_REG_WDOG_HUN_SECS	0x08
154 #define DS1388_REG_WDOG_SECS		0x09
155 #define DS1388_REG_FLAG			0x0b
156 #	define DS1388_BIT_WF		BIT(6)
157 #	define DS1388_BIT_OSF		BIT(7)
158 #define DS1388_REG_CONTROL		0x0c
159 #	define DS1388_BIT_RST		BIT(0)
160 #	define DS1388_BIT_WDE		BIT(1)
161 #	define DS1388_BIT_nEOSC		BIT(7)
162 
163 /* negative offset step is -2.034ppm */
164 #define M41TXX_NEG_OFFSET_STEP_PPB	2034
165 /* positive offset step is +4.068ppm */
166 #define M41TXX_POS_OFFSET_STEP_PPB	4068
167 /* Min and max values supported with 'offset' interface by M41TXX */
168 #define M41TXX_MIN_OFFSET	((-31) * M41TXX_NEG_OFFSET_STEP_PPB)
169 #define M41TXX_MAX_OFFSET	((31) * M41TXX_POS_OFFSET_STEP_PPB)
170 
171 struct ds1307 {
172 	enum ds_type		type;
173 	struct device		*dev;
174 	struct regmap		*regmap;
175 	const char		*name;
176 	struct rtc_device	*rtc;
177 #ifdef CONFIG_COMMON_CLK
178 	struct clk_hw		clks[2];
179 #endif
180 };
181 
182 struct chip_desc {
183 	unsigned		alarm:1;
184 	u16			nvram_offset;
185 	u16			nvram_size;
186 	u8			offset; /* register's offset */
187 	u8			century_reg;
188 	u8			century_enable_bit;
189 	u8			century_bit;
190 	u8			bbsqi_bit;
191 	irq_handler_t		irq_handler;
192 	const struct rtc_class_ops *rtc_ops;
193 	u16			trickle_charger_reg;
194 	u8			(*do_trickle_setup)(struct ds1307 *, u32,
195 						    bool);
196 	/* Does the RTC require trickle-resistor-ohms to select the value of
197 	 * the resistor between Vcc and Vbackup?
198 	 */
199 	bool			requires_trickle_resistor;
200 	/* Some RTC's batteries and supercaps were charged by default, others
201 	 * allow charging but were not configured previously to do so.
202 	 * Remember this behavior to stay backwards compatible.
203 	 */
204 	bool			charge_default;
205 };
206 
207 static const struct chip_desc chips[last_ds_type];
208 
209 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
210 {
211 	struct ds1307	*ds1307 = dev_get_drvdata(dev);
212 	int		tmp, ret;
213 	const struct chip_desc *chip = &chips[ds1307->type];
214 	u8 regs[7];
215 
216 	if (ds1307->type == rx_8130) {
217 		unsigned int regflag;
218 		ret = regmap_read(ds1307->regmap, RX8130_REG_FLAG, &regflag);
219 		if (ret) {
220 			dev_err(dev, "%s error %d\n", "read", ret);
221 			return ret;
222 		}
223 
224 		if (regflag & RX8130_REG_FLAG_VLF) {
225 			dev_warn_once(dev, "oscillator failed, set time!\n");
226 			return -EINVAL;
227 		}
228 	}
229 
230 	/* read the RTC date and time registers all at once */
231 	ret = regmap_bulk_read(ds1307->regmap, chip->offset, regs,
232 			       sizeof(regs));
233 	if (ret) {
234 		dev_err(dev, "%s error %d\n", "read", ret);
235 		return ret;
236 	}
237 
238 	dev_dbg(dev, "%s: %7ph\n", "read", regs);
239 
240 	/* if oscillator fail bit is set, no data can be trusted */
241 	if (ds1307->type == m41t0 &&
242 	    regs[DS1307_REG_MIN] & M41T0_BIT_OF) {
243 		dev_warn_once(dev, "oscillator failed, set time!\n");
244 		return -EINVAL;
245 	} else if (ds1307->type == mcp794xx &&
246 	    !(regs[DS1307_REG_WDAY] & MCP794XX_BIT_OSCRUN)) {
247 		dev_warn_once(dev, "oscillator failed, set time!\n");
248 		return -EINVAL;
249 	}
250 
251 	tmp = regs[DS1307_REG_SECS];
252 	switch (ds1307->type) {
253 	case ds_1307:
254 	case m41t0:
255 	case m41t00:
256 	case m41t11:
257 		if (tmp & DS1307_BIT_CH)
258 			return -EINVAL;
259 		break;
260 	case ds_1308:
261 	case ds_1338:
262 		if (tmp & DS1307_BIT_CH)
263 			return -EINVAL;
264 
265 		ret = regmap_read(ds1307->regmap, DS1307_REG_CONTROL, &tmp);
266 		if (ret)
267 			return ret;
268 		if (tmp & DS1338_BIT_OSF)
269 			return -EINVAL;
270 		break;
271 	case ds_1337:
272 	case ds_1339:
273 	case ds_1341:
274 	case ds_3231:
275 		ret = regmap_read(ds1307->regmap, DS1337_REG_STATUS, &tmp);
276 		if (ret)
277 			return ret;
278 		if (tmp & DS1337_BIT_OSF)
279 			return -EINVAL;
280 		break;
281 	case ds_1340:
282 		if (tmp & DS1340_BIT_nEOSC)
283 			return -EINVAL;
284 
285 		ret = regmap_read(ds1307->regmap, DS1340_REG_FLAG, &tmp);
286 		if (ret)
287 			return ret;
288 		if (tmp & DS1340_BIT_OSF)
289 			return -EINVAL;
290 		break;
291 	case ds_1388:
292 		ret = regmap_read(ds1307->regmap, DS1388_REG_FLAG, &tmp);
293 		if (ret)
294 			return ret;
295 		if (tmp & DS1388_BIT_OSF)
296 			return -EINVAL;
297 		break;
298 	case mcp794xx:
299 		if (!(tmp & MCP794XX_BIT_ST))
300 			return -EINVAL;
301 
302 		break;
303 	default:
304 		break;
305 	}
306 
307 	t->tm_sec = bcd2bin(regs[DS1307_REG_SECS] & 0x7f);
308 	t->tm_min = bcd2bin(regs[DS1307_REG_MIN] & 0x7f);
309 	tmp = regs[DS1307_REG_HOUR] & 0x3f;
310 	t->tm_hour = bcd2bin(tmp);
311 	/* rx8130 is bit position, not BCD */
312 	if (ds1307->type == rx_8130)
313 		t->tm_wday = fls(regs[DS1307_REG_WDAY] & 0x7f) - 1;
314 	else
315 		t->tm_wday = bcd2bin(regs[DS1307_REG_WDAY] & 0x07) - 1;
316 	t->tm_mday = bcd2bin(regs[DS1307_REG_MDAY] & 0x3f);
317 	tmp = regs[DS1307_REG_MONTH] & 0x1f;
318 	t->tm_mon = bcd2bin(tmp) - 1;
319 	t->tm_year = bcd2bin(regs[DS1307_REG_YEAR]) + 100;
320 
321 	if (regs[chip->century_reg] & chip->century_bit &&
322 	    IS_ENABLED(CONFIG_RTC_DRV_DS1307_CENTURY))
323 		t->tm_year += 100;
324 
325 	dev_dbg(dev, "%s secs=%d, mins=%d, "
326 		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
327 		"read", t->tm_sec, t->tm_min,
328 		t->tm_hour, t->tm_mday,
329 		t->tm_mon, t->tm_year, t->tm_wday);
330 
331 	return 0;
332 }
333 
334 static int ds1307_set_time(struct device *dev, struct rtc_time *t)
335 {
336 	struct ds1307	*ds1307 = dev_get_drvdata(dev);
337 	const struct chip_desc *chip = &chips[ds1307->type];
338 	int		result;
339 	int		tmp;
340 	u8		regs[7];
341 
342 	dev_dbg(dev, "%s secs=%d, mins=%d, "
343 		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
344 		"write", t->tm_sec, t->tm_min,
345 		t->tm_hour, t->tm_mday,
346 		t->tm_mon, t->tm_year, t->tm_wday);
347 
348 	if (t->tm_year < 100)
349 		return -EINVAL;
350 
351 #ifdef CONFIG_RTC_DRV_DS1307_CENTURY
352 	if (t->tm_year > (chip->century_bit ? 299 : 199))
353 		return -EINVAL;
354 #else
355 	if (t->tm_year > 199)
356 		return -EINVAL;
357 #endif
358 
359 	regs[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
360 	regs[DS1307_REG_MIN] = bin2bcd(t->tm_min);
361 	regs[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
362 	/* rx8130 is bit position, not BCD */
363 	if (ds1307->type == rx_8130)
364 		regs[DS1307_REG_WDAY] = 1 << t->tm_wday;
365 	else
366 		regs[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
367 	regs[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
368 	regs[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
369 
370 	/* assume 20YY not 19YY */
371 	tmp = t->tm_year % 100;
372 	regs[DS1307_REG_YEAR] = bin2bcd(tmp);
373 
374 	if (chip->century_enable_bit)
375 		regs[chip->century_reg] |= chip->century_enable_bit;
376 	if (t->tm_year > 199 && chip->century_bit)
377 		regs[chip->century_reg] |= chip->century_bit;
378 
379 	switch (ds1307->type) {
380 	case ds_1308:
381 	case ds_1338:
382 		regmap_update_bits(ds1307->regmap, DS1307_REG_CONTROL,
383 				   DS1338_BIT_OSF, 0);
384 		break;
385 	case ds_1337:
386 	case ds_1339:
387 	case ds_1341:
388 	case ds_3231:
389 		regmap_update_bits(ds1307->regmap, DS1337_REG_STATUS,
390 				   DS1337_BIT_OSF, 0);
391 		break;
392 	case ds_1340:
393 		regmap_update_bits(ds1307->regmap, DS1340_REG_FLAG,
394 				   DS1340_BIT_OSF, 0);
395 		break;
396 	case ds_1388:
397 		regmap_update_bits(ds1307->regmap, DS1388_REG_FLAG,
398 				   DS1388_BIT_OSF, 0);
399 		break;
400 	case mcp794xx:
401 		/*
402 		 * these bits were cleared when preparing the date/time
403 		 * values and need to be set again before writing the
404 		 * regsfer out to the device.
405 		 */
406 		regs[DS1307_REG_SECS] |= MCP794XX_BIT_ST;
407 		regs[DS1307_REG_WDAY] |= MCP794XX_BIT_VBATEN;
408 		break;
409 	default:
410 		break;
411 	}
412 
413 	dev_dbg(dev, "%s: %7ph\n", "write", regs);
414 
415 	result = regmap_bulk_write(ds1307->regmap, chip->offset, regs,
416 				   sizeof(regs));
417 	if (result) {
418 		dev_err(dev, "%s error %d\n", "write", result);
419 		return result;
420 	}
421 
422 	if (ds1307->type == rx_8130) {
423 		/* clear Voltage Loss Flag as data is available now */
424 		result = regmap_write(ds1307->regmap, RX8130_REG_FLAG,
425 				      ~(u8)RX8130_REG_FLAG_VLF);
426 		if (result) {
427 			dev_err(dev, "%s error %d\n", "write", result);
428 			return result;
429 		}
430 	}
431 
432 	return 0;
433 }
434 
435 static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
436 {
437 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
438 	int			ret;
439 	u8			regs[9];
440 
441 	/* read all ALARM1, ALARM2, and status registers at once */
442 	ret = regmap_bulk_read(ds1307->regmap, DS1339_REG_ALARM1_SECS,
443 			       regs, sizeof(regs));
444 	if (ret) {
445 		dev_err(dev, "%s error %d\n", "alarm read", ret);
446 		return ret;
447 	}
448 
449 	dev_dbg(dev, "%s: %4ph, %3ph, %2ph\n", "alarm read",
450 		&regs[0], &regs[4], &regs[7]);
451 
452 	/*
453 	 * report alarm time (ALARM1); assume 24 hour and day-of-month modes,
454 	 * and that all four fields are checked matches
455 	 */
456 	t->time.tm_sec = bcd2bin(regs[0] & 0x7f);
457 	t->time.tm_min = bcd2bin(regs[1] & 0x7f);
458 	t->time.tm_hour = bcd2bin(regs[2] & 0x3f);
459 	t->time.tm_mday = bcd2bin(regs[3] & 0x3f);
460 
461 	/* ... and status */
462 	t->enabled = !!(regs[7] & DS1337_BIT_A1IE);
463 	t->pending = !!(regs[8] & DS1337_BIT_A1I);
464 
465 	dev_dbg(dev, "%s secs=%d, mins=%d, "
466 		"hours=%d, mday=%d, enabled=%d, pending=%d\n",
467 		"alarm read", t->time.tm_sec, t->time.tm_min,
468 		t->time.tm_hour, t->time.tm_mday,
469 		t->enabled, t->pending);
470 
471 	return 0;
472 }
473 
474 static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
475 {
476 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
477 	unsigned char		regs[9];
478 	u8			control, status;
479 	int			ret;
480 
481 	dev_dbg(dev, "%s secs=%d, mins=%d, "
482 		"hours=%d, mday=%d, enabled=%d, pending=%d\n",
483 		"alarm set", t->time.tm_sec, t->time.tm_min,
484 		t->time.tm_hour, t->time.tm_mday,
485 		t->enabled, t->pending);
486 
487 	/* read current status of both alarms and the chip */
488 	ret = regmap_bulk_read(ds1307->regmap, DS1339_REG_ALARM1_SECS, regs,
489 			       sizeof(regs));
490 	if (ret) {
491 		dev_err(dev, "%s error %d\n", "alarm write", ret);
492 		return ret;
493 	}
494 	control = regs[7];
495 	status = regs[8];
496 
497 	dev_dbg(dev, "%s: %4ph, %3ph, %02x %02x\n", "alarm set (old status)",
498 		&regs[0], &regs[4], control, status);
499 
500 	/* set ALARM1, using 24 hour and day-of-month modes */
501 	regs[0] = bin2bcd(t->time.tm_sec);
502 	regs[1] = bin2bcd(t->time.tm_min);
503 	regs[2] = bin2bcd(t->time.tm_hour);
504 	regs[3] = bin2bcd(t->time.tm_mday);
505 
506 	/* set ALARM2 to non-garbage */
507 	regs[4] = 0;
508 	regs[5] = 0;
509 	regs[6] = 0;
510 
511 	/* disable alarms */
512 	regs[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
513 	regs[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
514 
515 	ret = regmap_bulk_write(ds1307->regmap, DS1339_REG_ALARM1_SECS, regs,
516 				sizeof(regs));
517 	if (ret) {
518 		dev_err(dev, "can't set alarm time\n");
519 		return ret;
520 	}
521 
522 	/* optionally enable ALARM1 */
523 	if (t->enabled) {
524 		dev_dbg(dev, "alarm IRQ armed\n");
525 		regs[7] |= DS1337_BIT_A1IE;	/* only ALARM1 is used */
526 		regmap_write(ds1307->regmap, DS1337_REG_CONTROL, regs[7]);
527 	}
528 
529 	return 0;
530 }
531 
532 static int ds1307_alarm_irq_enable(struct device *dev, unsigned int enabled)
533 {
534 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
535 
536 	return regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
537 				  DS1337_BIT_A1IE,
538 				  enabled ? DS1337_BIT_A1IE : 0);
539 }
540 
541 static u8 do_trickle_setup_ds1339(struct ds1307 *ds1307, u32 ohms, bool diode)
542 {
543 	u8 setup = (diode) ? DS1307_TRICKLE_CHARGER_DIODE :
544 		DS1307_TRICKLE_CHARGER_NO_DIODE;
545 
546 	setup |= DS13XX_TRICKLE_CHARGER_MAGIC;
547 
548 	switch (ohms) {
549 	case 250:
550 		setup |= DS1307_TRICKLE_CHARGER_250_OHM;
551 		break;
552 	case 2000:
553 		setup |= DS1307_TRICKLE_CHARGER_2K_OHM;
554 		break;
555 	case 4000:
556 		setup |= DS1307_TRICKLE_CHARGER_4K_OHM;
557 		break;
558 	default:
559 		dev_warn(ds1307->dev,
560 			 "Unsupported ohm value %u in dt\n", ohms);
561 		return 0;
562 	}
563 	return setup;
564 }
565 
566 static u8 do_trickle_setup_rx8130(struct ds1307 *ds1307, u32 ohms, bool diode)
567 {
568 	/* make sure that the backup battery is enabled */
569 	u8 setup = RX8130_REG_CONTROL1_INIEN;
570 	if (diode)
571 		setup |= RX8130_REG_CONTROL1_CHGEN;
572 
573 	return setup;
574 }
575 
576 static irqreturn_t rx8130_irq(int irq, void *dev_id)
577 {
578 	struct ds1307           *ds1307 = dev_id;
579 	u8 ctl[3];
580 	int ret;
581 
582 	rtc_lock(ds1307->rtc);
583 
584 	/* Read control registers. */
585 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
586 			       sizeof(ctl));
587 	if (ret < 0)
588 		goto out;
589 	if (!(ctl[1] & RX8130_REG_FLAG_AF))
590 		goto out;
591 	ctl[1] &= ~RX8130_REG_FLAG_AF;
592 	ctl[2] &= ~RX8130_REG_CONTROL0_AIE;
593 
594 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
595 				sizeof(ctl));
596 	if (ret < 0)
597 		goto out;
598 
599 	rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
600 
601 out:
602 	rtc_unlock(ds1307->rtc);
603 
604 	return IRQ_HANDLED;
605 }
606 
607 static int rx8130_read_alarm(struct device *dev, struct rtc_wkalrm *t)
608 {
609 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
610 	u8 ald[3], ctl[3];
611 	int ret;
612 
613 	/* Read alarm registers. */
614 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_ALARM_MIN, ald,
615 			       sizeof(ald));
616 	if (ret < 0)
617 		return ret;
618 
619 	/* Read control registers. */
620 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
621 			       sizeof(ctl));
622 	if (ret < 0)
623 		return ret;
624 
625 	t->enabled = !!(ctl[2] & RX8130_REG_CONTROL0_AIE);
626 	t->pending = !!(ctl[1] & RX8130_REG_FLAG_AF);
627 
628 	/* Report alarm 0 time assuming 24-hour and day-of-month modes. */
629 	t->time.tm_sec = -1;
630 	t->time.tm_min = bcd2bin(ald[0] & 0x7f);
631 	t->time.tm_hour = bcd2bin(ald[1] & 0x7f);
632 	t->time.tm_wday = -1;
633 	t->time.tm_mday = bcd2bin(ald[2] & 0x7f);
634 	t->time.tm_mon = -1;
635 	t->time.tm_year = -1;
636 	t->time.tm_yday = -1;
637 	t->time.tm_isdst = -1;
638 
639 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d enabled=%d\n",
640 		__func__, t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
641 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled);
642 
643 	return 0;
644 }
645 
646 static int rx8130_set_alarm(struct device *dev, struct rtc_wkalrm *t)
647 {
648 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
649 	u8 ald[3], ctl[3];
650 	int ret;
651 
652 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
653 		"enabled=%d pending=%d\n", __func__,
654 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
655 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
656 		t->enabled, t->pending);
657 
658 	/* Read control registers. */
659 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
660 			       sizeof(ctl));
661 	if (ret < 0)
662 		return ret;
663 
664 	ctl[0] &= RX8130_REG_EXTENSION_WADA;
665 	ctl[1] &= ~RX8130_REG_FLAG_AF;
666 	ctl[2] &= ~RX8130_REG_CONTROL0_AIE;
667 
668 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
669 				sizeof(ctl));
670 	if (ret < 0)
671 		return ret;
672 
673 	/* Hardware alarm precision is 1 minute! */
674 	ald[0] = bin2bcd(t->time.tm_min);
675 	ald[1] = bin2bcd(t->time.tm_hour);
676 	ald[2] = bin2bcd(t->time.tm_mday);
677 
678 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_ALARM_MIN, ald,
679 				sizeof(ald));
680 	if (ret < 0)
681 		return ret;
682 
683 	if (!t->enabled)
684 		return 0;
685 
686 	ctl[2] |= RX8130_REG_CONTROL0_AIE;
687 
688 	return regmap_write(ds1307->regmap, RX8130_REG_CONTROL0, ctl[2]);
689 }
690 
691 static int rx8130_alarm_irq_enable(struct device *dev, unsigned int enabled)
692 {
693 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
694 	int ret, reg;
695 
696 	ret = regmap_read(ds1307->regmap, RX8130_REG_CONTROL0, &reg);
697 	if (ret < 0)
698 		return ret;
699 
700 	if (enabled)
701 		reg |= RX8130_REG_CONTROL0_AIE;
702 	else
703 		reg &= ~RX8130_REG_CONTROL0_AIE;
704 
705 	return regmap_write(ds1307->regmap, RX8130_REG_CONTROL0, reg);
706 }
707 
708 static irqreturn_t mcp794xx_irq(int irq, void *dev_id)
709 {
710 	struct ds1307           *ds1307 = dev_id;
711 	struct mutex            *lock = &ds1307->rtc->ops_lock;
712 	int reg, ret;
713 
714 	mutex_lock(lock);
715 
716 	/* Check and clear alarm 0 interrupt flag. */
717 	ret = regmap_read(ds1307->regmap, MCP794XX_REG_ALARM0_CTRL, &reg);
718 	if (ret)
719 		goto out;
720 	if (!(reg & MCP794XX_BIT_ALMX_IF))
721 		goto out;
722 	reg &= ~MCP794XX_BIT_ALMX_IF;
723 	ret = regmap_write(ds1307->regmap, MCP794XX_REG_ALARM0_CTRL, reg);
724 	if (ret)
725 		goto out;
726 
727 	/* Disable alarm 0. */
728 	ret = regmap_update_bits(ds1307->regmap, MCP794XX_REG_CONTROL,
729 				 MCP794XX_BIT_ALM0_EN, 0);
730 	if (ret)
731 		goto out;
732 
733 	rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
734 
735 out:
736 	mutex_unlock(lock);
737 
738 	return IRQ_HANDLED;
739 }
740 
741 static int mcp794xx_read_alarm(struct device *dev, struct rtc_wkalrm *t)
742 {
743 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
744 	u8 regs[10];
745 	int ret;
746 
747 	/* Read control and alarm 0 registers. */
748 	ret = regmap_bulk_read(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
749 			       sizeof(regs));
750 	if (ret)
751 		return ret;
752 
753 	t->enabled = !!(regs[0] & MCP794XX_BIT_ALM0_EN);
754 
755 	/* Report alarm 0 time assuming 24-hour and day-of-month modes. */
756 	t->time.tm_sec = bcd2bin(regs[3] & 0x7f);
757 	t->time.tm_min = bcd2bin(regs[4] & 0x7f);
758 	t->time.tm_hour = bcd2bin(regs[5] & 0x3f);
759 	t->time.tm_wday = bcd2bin(regs[6] & 0x7) - 1;
760 	t->time.tm_mday = bcd2bin(regs[7] & 0x3f);
761 	t->time.tm_mon = bcd2bin(regs[8] & 0x1f) - 1;
762 	t->time.tm_year = -1;
763 	t->time.tm_yday = -1;
764 	t->time.tm_isdst = -1;
765 
766 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
767 		"enabled=%d polarity=%d irq=%d match=%lu\n", __func__,
768 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
769 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled,
770 		!!(regs[6] & MCP794XX_BIT_ALMX_POL),
771 		!!(regs[6] & MCP794XX_BIT_ALMX_IF),
772 		(regs[6] & MCP794XX_MSK_ALMX_MATCH) >> 4);
773 
774 	return 0;
775 }
776 
777 /*
778  * We may have a random RTC weekday, therefore calculate alarm weekday based
779  * on current weekday we read from the RTC timekeeping regs
780  */
781 static int mcp794xx_alm_weekday(struct device *dev, struct rtc_time *tm_alarm)
782 {
783 	struct rtc_time tm_now;
784 	int days_now, days_alarm, ret;
785 
786 	ret = ds1307_get_time(dev, &tm_now);
787 	if (ret)
788 		return ret;
789 
790 	days_now = div_s64(rtc_tm_to_time64(&tm_now), 24 * 60 * 60);
791 	days_alarm = div_s64(rtc_tm_to_time64(tm_alarm), 24 * 60 * 60);
792 
793 	return (tm_now.tm_wday + days_alarm - days_now) % 7 + 1;
794 }
795 
796 static int mcp794xx_set_alarm(struct device *dev, struct rtc_wkalrm *t)
797 {
798 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
799 	unsigned char regs[10];
800 	int wday, ret;
801 
802 	wday = mcp794xx_alm_weekday(dev, &t->time);
803 	if (wday < 0)
804 		return wday;
805 
806 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
807 		"enabled=%d pending=%d\n", __func__,
808 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
809 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
810 		t->enabled, t->pending);
811 
812 	/* Read control and alarm 0 registers. */
813 	ret = regmap_bulk_read(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
814 			       sizeof(regs));
815 	if (ret)
816 		return ret;
817 
818 	/* Set alarm 0, using 24-hour and day-of-month modes. */
819 	regs[3] = bin2bcd(t->time.tm_sec);
820 	regs[4] = bin2bcd(t->time.tm_min);
821 	regs[5] = bin2bcd(t->time.tm_hour);
822 	regs[6] = wday;
823 	regs[7] = bin2bcd(t->time.tm_mday);
824 	regs[8] = bin2bcd(t->time.tm_mon + 1);
825 
826 	/* Clear the alarm 0 interrupt flag. */
827 	regs[6] &= ~MCP794XX_BIT_ALMX_IF;
828 	/* Set alarm match: second, minute, hour, day, date, month. */
829 	regs[6] |= MCP794XX_MSK_ALMX_MATCH;
830 	/* Disable interrupt. We will not enable until completely programmed */
831 	regs[0] &= ~MCP794XX_BIT_ALM0_EN;
832 
833 	ret = regmap_bulk_write(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
834 				sizeof(regs));
835 	if (ret)
836 		return ret;
837 
838 	if (!t->enabled)
839 		return 0;
840 	regs[0] |= MCP794XX_BIT_ALM0_EN;
841 	return regmap_write(ds1307->regmap, MCP794XX_REG_CONTROL, regs[0]);
842 }
843 
844 static int mcp794xx_alarm_irq_enable(struct device *dev, unsigned int enabled)
845 {
846 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
847 
848 	return regmap_update_bits(ds1307->regmap, MCP794XX_REG_CONTROL,
849 				  MCP794XX_BIT_ALM0_EN,
850 				  enabled ? MCP794XX_BIT_ALM0_EN : 0);
851 }
852 
853 static int m41txx_rtc_read_offset(struct device *dev, long *offset)
854 {
855 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
856 	unsigned int ctrl_reg;
857 	u8 val;
858 
859 	regmap_read(ds1307->regmap, M41TXX_REG_CONTROL, &ctrl_reg);
860 
861 	val = ctrl_reg & M41TXX_M_CALIBRATION;
862 
863 	/* check if positive */
864 	if (ctrl_reg & M41TXX_BIT_CALIB_SIGN)
865 		*offset = (val * M41TXX_POS_OFFSET_STEP_PPB);
866 	else
867 		*offset = -(val * M41TXX_NEG_OFFSET_STEP_PPB);
868 
869 	return 0;
870 }
871 
872 static int m41txx_rtc_set_offset(struct device *dev, long offset)
873 {
874 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
875 	unsigned int ctrl_reg;
876 
877 	if ((offset < M41TXX_MIN_OFFSET) || (offset > M41TXX_MAX_OFFSET))
878 		return -ERANGE;
879 
880 	if (offset >= 0) {
881 		ctrl_reg = DIV_ROUND_CLOSEST(offset,
882 					     M41TXX_POS_OFFSET_STEP_PPB);
883 		ctrl_reg |= M41TXX_BIT_CALIB_SIGN;
884 	} else {
885 		ctrl_reg = DIV_ROUND_CLOSEST(abs(offset),
886 					     M41TXX_NEG_OFFSET_STEP_PPB);
887 	}
888 
889 	return regmap_update_bits(ds1307->regmap, M41TXX_REG_CONTROL,
890 				  M41TXX_M_CALIBRATION | M41TXX_BIT_CALIB_SIGN,
891 				  ctrl_reg);
892 }
893 
894 #ifdef CONFIG_WATCHDOG_CORE
895 static int ds1388_wdt_start(struct watchdog_device *wdt_dev)
896 {
897 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
898 	u8 regs[2];
899 	int ret;
900 
901 	ret = regmap_update_bits(ds1307->regmap, DS1388_REG_FLAG,
902 				 DS1388_BIT_WF, 0);
903 	if (ret)
904 		return ret;
905 
906 	ret = regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
907 				 DS1388_BIT_WDE | DS1388_BIT_RST, 0);
908 	if (ret)
909 		return ret;
910 
911 	/*
912 	 * watchdog timeouts are measured in seconds. So ignore hundredths of
913 	 * seconds field.
914 	 */
915 	regs[0] = 0;
916 	regs[1] = bin2bcd(wdt_dev->timeout);
917 
918 	ret = regmap_bulk_write(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
919 				sizeof(regs));
920 	if (ret)
921 		return ret;
922 
923 	return regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
924 				  DS1388_BIT_WDE | DS1388_BIT_RST,
925 				  DS1388_BIT_WDE | DS1388_BIT_RST);
926 }
927 
928 static int ds1388_wdt_stop(struct watchdog_device *wdt_dev)
929 {
930 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
931 
932 	return regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
933 				  DS1388_BIT_WDE | DS1388_BIT_RST, 0);
934 }
935 
936 static int ds1388_wdt_ping(struct watchdog_device *wdt_dev)
937 {
938 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
939 	u8 regs[2];
940 
941 	return regmap_bulk_read(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
942 				sizeof(regs));
943 }
944 
945 static int ds1388_wdt_set_timeout(struct watchdog_device *wdt_dev,
946 				  unsigned int val)
947 {
948 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
949 	u8 regs[2];
950 
951 	wdt_dev->timeout = val;
952 	regs[0] = 0;
953 	regs[1] = bin2bcd(wdt_dev->timeout);
954 
955 	return regmap_bulk_write(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
956 				 sizeof(regs));
957 }
958 #endif
959 
960 static const struct rtc_class_ops rx8130_rtc_ops = {
961 	.read_time      = ds1307_get_time,
962 	.set_time       = ds1307_set_time,
963 	.read_alarm     = rx8130_read_alarm,
964 	.set_alarm      = rx8130_set_alarm,
965 	.alarm_irq_enable = rx8130_alarm_irq_enable,
966 };
967 
968 static const struct rtc_class_ops mcp794xx_rtc_ops = {
969 	.read_time      = ds1307_get_time,
970 	.set_time       = ds1307_set_time,
971 	.read_alarm     = mcp794xx_read_alarm,
972 	.set_alarm      = mcp794xx_set_alarm,
973 	.alarm_irq_enable = mcp794xx_alarm_irq_enable,
974 };
975 
976 static const struct rtc_class_ops m41txx_rtc_ops = {
977 	.read_time      = ds1307_get_time,
978 	.set_time       = ds1307_set_time,
979 	.read_alarm	= ds1337_read_alarm,
980 	.set_alarm	= ds1337_set_alarm,
981 	.alarm_irq_enable = ds1307_alarm_irq_enable,
982 	.read_offset	= m41txx_rtc_read_offset,
983 	.set_offset	= m41txx_rtc_set_offset,
984 };
985 
986 static const struct chip_desc chips[last_ds_type] = {
987 	[ds_1307] = {
988 		.nvram_offset	= 8,
989 		.nvram_size	= 56,
990 	},
991 	[ds_1308] = {
992 		.nvram_offset	= 8,
993 		.nvram_size	= 56,
994 	},
995 	[ds_1337] = {
996 		.alarm		= 1,
997 		.century_reg	= DS1307_REG_MONTH,
998 		.century_bit	= DS1337_BIT_CENTURY,
999 	},
1000 	[ds_1338] = {
1001 		.nvram_offset	= 8,
1002 		.nvram_size	= 56,
1003 	},
1004 	[ds_1339] = {
1005 		.alarm		= 1,
1006 		.century_reg	= DS1307_REG_MONTH,
1007 		.century_bit	= DS1337_BIT_CENTURY,
1008 		.bbsqi_bit	= DS1339_BIT_BBSQI,
1009 		.trickle_charger_reg = 0x10,
1010 		.do_trickle_setup = &do_trickle_setup_ds1339,
1011 		.requires_trickle_resistor = true,
1012 		.charge_default = true,
1013 	},
1014 	[ds_1340] = {
1015 		.century_reg	= DS1307_REG_HOUR,
1016 		.century_enable_bit = DS1340_BIT_CENTURY_EN,
1017 		.century_bit	= DS1340_BIT_CENTURY,
1018 		.do_trickle_setup = &do_trickle_setup_ds1339,
1019 		.trickle_charger_reg = 0x08,
1020 		.requires_trickle_resistor = true,
1021 		.charge_default = true,
1022 	},
1023 	[ds_1341] = {
1024 		.century_reg	= DS1307_REG_MONTH,
1025 		.century_bit	= DS1337_BIT_CENTURY,
1026 	},
1027 	[ds_1388] = {
1028 		.offset		= 1,
1029 		.trickle_charger_reg = 0x0a,
1030 	},
1031 	[ds_3231] = {
1032 		.alarm		= 1,
1033 		.century_reg	= DS1307_REG_MONTH,
1034 		.century_bit	= DS1337_BIT_CENTURY,
1035 		.bbsqi_bit	= DS3231_BIT_BBSQW,
1036 	},
1037 	[rx_8130] = {
1038 		.alarm		= 1,
1039 		/* this is battery backed SRAM */
1040 		.nvram_offset	= 0x20,
1041 		.nvram_size	= 4,	/* 32bit (4 word x 8 bit) */
1042 		.offset		= 0x10,
1043 		.irq_handler = rx8130_irq,
1044 		.rtc_ops = &rx8130_rtc_ops,
1045 		.trickle_charger_reg = RX8130_REG_CONTROL1,
1046 		.do_trickle_setup = &do_trickle_setup_rx8130,
1047 	},
1048 	[m41t0] = {
1049 		.rtc_ops	= &m41txx_rtc_ops,
1050 	},
1051 	[m41t00] = {
1052 		.rtc_ops	= &m41txx_rtc_ops,
1053 	},
1054 	[m41t11] = {
1055 		/* this is battery backed SRAM */
1056 		.nvram_offset	= 8,
1057 		.nvram_size	= 56,
1058 		.rtc_ops	= &m41txx_rtc_ops,
1059 	},
1060 	[mcp794xx] = {
1061 		.alarm		= 1,
1062 		/* this is battery backed SRAM */
1063 		.nvram_offset	= 0x20,
1064 		.nvram_size	= 0x40,
1065 		.irq_handler = mcp794xx_irq,
1066 		.rtc_ops = &mcp794xx_rtc_ops,
1067 	},
1068 };
1069 
1070 static const struct i2c_device_id ds1307_id[] = {
1071 	{ .name = "ds1307", .driver_data = ds_1307 },
1072 	{ .name = "ds1308", .driver_data = ds_1308 },
1073 	{ .name = "ds1337", .driver_data = ds_1337 },
1074 	{ .name = "ds1338", .driver_data = ds_1338 },
1075 	{ .name = "ds1339", .driver_data = ds_1339 },
1076 	{ .name = "ds1388", .driver_data = ds_1388 },
1077 	{ .name = "ds1340", .driver_data = ds_1340 },
1078 	{ .name = "ds1341", .driver_data = ds_1341 },
1079 	{ .name = "ds3231", .driver_data = ds_3231 },
1080 	{ .name = "m41t0", .driver_data = m41t0 },
1081 	{ .name = "m41t00", .driver_data = m41t00 },
1082 	{ .name = "m41t11", .driver_data = m41t11 },
1083 	{ .name = "mcp7940x", .driver_data = mcp794xx },
1084 	{ .name = "mcp7941x", .driver_data = mcp794xx },
1085 	{ .name = "pt7c4338", .driver_data = ds_1307 },
1086 	{ .name = "rx8025", .driver_data = rx_8025 },
1087 	{ .name = "isl12057", .driver_data = ds_1337 },
1088 	{ .name = "rx8130", .driver_data = rx_8130 },
1089 	{ }
1090 };
1091 MODULE_DEVICE_TABLE(i2c, ds1307_id);
1092 
1093 static const struct of_device_id ds1307_of_match[] = {
1094 	{
1095 		.compatible = "dallas,ds1307",
1096 		.data = (void *)ds_1307
1097 	},
1098 	{
1099 		.compatible = "dallas,ds1308",
1100 		.data = (void *)ds_1308
1101 	},
1102 	{
1103 		.compatible = "dallas,ds1337",
1104 		.data = (void *)ds_1337
1105 	},
1106 	{
1107 		.compatible = "dallas,ds1338",
1108 		.data = (void *)ds_1338
1109 	},
1110 	{
1111 		.compatible = "dallas,ds1339",
1112 		.data = (void *)ds_1339
1113 	},
1114 	{
1115 		.compatible = "dallas,ds1388",
1116 		.data = (void *)ds_1388
1117 	},
1118 	{
1119 		.compatible = "dallas,ds1340",
1120 		.data = (void *)ds_1340
1121 	},
1122 	{
1123 		.compatible = "dallas,ds1341",
1124 		.data = (void *)ds_1341
1125 	},
1126 	{
1127 		.compatible = "maxim,ds3231",
1128 		.data = (void *)ds_3231
1129 	},
1130 	{
1131 		.compatible = "st,m41t0",
1132 		.data = (void *)m41t0
1133 	},
1134 	{
1135 		.compatible = "st,m41t00",
1136 		.data = (void *)m41t00
1137 	},
1138 	{
1139 		.compatible = "st,m41t11",
1140 		.data = (void *)m41t11
1141 	},
1142 	{
1143 		.compatible = "microchip,mcp7940x",
1144 		.data = (void *)mcp794xx
1145 	},
1146 	{
1147 		.compatible = "microchip,mcp7941x",
1148 		.data = (void *)mcp794xx
1149 	},
1150 	{
1151 		.compatible = "pericom,pt7c4338",
1152 		.data = (void *)ds_1307
1153 	},
1154 	{
1155 		.compatible = "epson,rx8025",
1156 		.data = (void *)rx_8025
1157 	},
1158 	{
1159 		.compatible = "isil,isl12057",
1160 		.data = (void *)ds_1337
1161 	},
1162 	{
1163 		.compatible = "epson,rx8130",
1164 		.data = (void *)rx_8130
1165 	},
1166 	{ }
1167 };
1168 MODULE_DEVICE_TABLE(of, ds1307_of_match);
1169 
1170 /*
1171  * The ds1337 and ds1339 both have two alarms, but we only use the first
1172  * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
1173  * signal; ds1339 chips have only one alarm signal.
1174  */
1175 static irqreturn_t ds1307_irq(int irq, void *dev_id)
1176 {
1177 	struct ds1307		*ds1307 = dev_id;
1178 	struct mutex		*lock = &ds1307->rtc->ops_lock;
1179 	int			stat, ret;
1180 
1181 	mutex_lock(lock);
1182 	ret = regmap_read(ds1307->regmap, DS1337_REG_STATUS, &stat);
1183 	if (ret)
1184 		goto out;
1185 
1186 	if (stat & DS1337_BIT_A1I) {
1187 		stat &= ~DS1337_BIT_A1I;
1188 		regmap_write(ds1307->regmap, DS1337_REG_STATUS, stat);
1189 
1190 		ret = regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
1191 					 DS1337_BIT_A1IE, 0);
1192 		if (ret)
1193 			goto out;
1194 
1195 		rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
1196 	}
1197 
1198 out:
1199 	mutex_unlock(lock);
1200 
1201 	return IRQ_HANDLED;
1202 }
1203 
1204 /*----------------------------------------------------------------------*/
1205 
1206 static const struct rtc_class_ops ds13xx_rtc_ops = {
1207 	.read_time	= ds1307_get_time,
1208 	.set_time	= ds1307_set_time,
1209 	.read_alarm	= ds1337_read_alarm,
1210 	.set_alarm	= ds1337_set_alarm,
1211 	.alarm_irq_enable = ds1307_alarm_irq_enable,
1212 };
1213 
1214 static ssize_t frequency_test_store(struct device *dev,
1215 				    struct device_attribute *attr,
1216 				    const char *buf, size_t count)
1217 {
1218 	struct ds1307 *ds1307 = dev_get_drvdata(dev->parent);
1219 	bool freq_test_en;
1220 	int ret;
1221 
1222 	ret = kstrtobool(buf, &freq_test_en);
1223 	if (ret) {
1224 		dev_err(dev, "Failed to store RTC Frequency Test attribute\n");
1225 		return ret;
1226 	}
1227 
1228 	regmap_update_bits(ds1307->regmap, M41TXX_REG_CONTROL, M41TXX_BIT_FT,
1229 			   freq_test_en ? M41TXX_BIT_FT : 0);
1230 
1231 	return count;
1232 }
1233 
1234 static ssize_t frequency_test_show(struct device *dev,
1235 				   struct device_attribute *attr,
1236 				   char *buf)
1237 {
1238 	struct ds1307 *ds1307 = dev_get_drvdata(dev->parent);
1239 	unsigned int ctrl_reg;
1240 
1241 	regmap_read(ds1307->regmap, M41TXX_REG_CONTROL, &ctrl_reg);
1242 
1243 	return sysfs_emit(buf, (ctrl_reg & M41TXX_BIT_FT) ? "on\n" : "off\n");
1244 }
1245 
1246 static DEVICE_ATTR_RW(frequency_test);
1247 
1248 static struct attribute *rtc_freq_test_attrs[] = {
1249 	&dev_attr_frequency_test.attr,
1250 	NULL,
1251 };
1252 
1253 static const struct attribute_group rtc_freq_test_attr_group = {
1254 	.attrs		= rtc_freq_test_attrs,
1255 };
1256 
1257 static int ds1307_add_frequency_test(struct ds1307 *ds1307)
1258 {
1259 	int err;
1260 
1261 	switch (ds1307->type) {
1262 	case m41t0:
1263 	case m41t00:
1264 	case m41t11:
1265 		err = rtc_add_group(ds1307->rtc, &rtc_freq_test_attr_group);
1266 		if (err)
1267 			return err;
1268 		break;
1269 	default:
1270 		break;
1271 	}
1272 
1273 	return 0;
1274 }
1275 
1276 /*----------------------------------------------------------------------*/
1277 
1278 static int ds1307_nvram_read(void *priv, unsigned int offset, void *val,
1279 			     size_t bytes)
1280 {
1281 	struct ds1307 *ds1307 = priv;
1282 	const struct chip_desc *chip = &chips[ds1307->type];
1283 
1284 	return regmap_bulk_read(ds1307->regmap, chip->nvram_offset + offset,
1285 				val, bytes);
1286 }
1287 
1288 static int ds1307_nvram_write(void *priv, unsigned int offset, void *val,
1289 			      size_t bytes)
1290 {
1291 	struct ds1307 *ds1307 = priv;
1292 	const struct chip_desc *chip = &chips[ds1307->type];
1293 
1294 	return regmap_bulk_write(ds1307->regmap, chip->nvram_offset + offset,
1295 				 val, bytes);
1296 }
1297 
1298 /*----------------------------------------------------------------------*/
1299 
1300 static u8 ds1307_trickle_init(struct ds1307 *ds1307,
1301 			      const struct chip_desc *chip)
1302 {
1303 	u32 ohms, chargeable;
1304 	bool diode = chip->charge_default;
1305 
1306 	if (!chip->do_trickle_setup)
1307 		return 0;
1308 
1309 	if (device_property_read_u32(ds1307->dev, "trickle-resistor-ohms",
1310 				     &ohms) && chip->requires_trickle_resistor)
1311 		return 0;
1312 
1313 	/* aux-voltage-chargeable takes precedence over the deprecated
1314 	 * trickle-diode-disable
1315 	 */
1316 	if (!device_property_read_u32(ds1307->dev, "aux-voltage-chargeable",
1317 				     &chargeable)) {
1318 		switch (chargeable) {
1319 		case 0:
1320 			diode = false;
1321 			break;
1322 		case 1:
1323 			diode = true;
1324 			break;
1325 		default:
1326 			dev_warn(ds1307->dev,
1327 				 "unsupported aux-voltage-chargeable value\n");
1328 			break;
1329 		}
1330 	} else if (device_property_read_bool(ds1307->dev,
1331 					     "trickle-diode-disable")) {
1332 		diode = false;
1333 	}
1334 
1335 	return chip->do_trickle_setup(ds1307, ohms, diode);
1336 }
1337 
1338 /*----------------------------------------------------------------------*/
1339 
1340 #if IS_REACHABLE(CONFIG_HWMON)
1341 
1342 /*
1343  * Temperature sensor support for ds3231 devices.
1344  */
1345 
1346 #define DS3231_REG_TEMPERATURE	0x11
1347 
1348 /*
1349  * A user-initiated temperature conversion is not started by this function,
1350  * so the temperature is updated once every 64 seconds.
1351  */
1352 static int ds3231_hwmon_read_temp(struct device *dev, s32 *mC)
1353 {
1354 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
1355 	u8 temp_buf[2];
1356 	s16 temp;
1357 	int ret;
1358 
1359 	ret = regmap_bulk_read(ds1307->regmap, DS3231_REG_TEMPERATURE,
1360 			       temp_buf, sizeof(temp_buf));
1361 	if (ret)
1362 		return ret;
1363 	/*
1364 	 * Temperature is represented as a 10-bit code with a resolution of
1365 	 * 0.25 degree celsius and encoded in two's complement format.
1366 	 */
1367 	temp = (temp_buf[0] << 8) | temp_buf[1];
1368 	temp >>= 6;
1369 	*mC = temp * 250;
1370 
1371 	return 0;
1372 }
1373 
1374 static ssize_t ds3231_hwmon_show_temp(struct device *dev,
1375 				      struct device_attribute *attr, char *buf)
1376 {
1377 	int ret;
1378 	s32 temp;
1379 
1380 	ret = ds3231_hwmon_read_temp(dev, &temp);
1381 	if (ret)
1382 		return ret;
1383 
1384 	return sprintf(buf, "%d\n", temp);
1385 }
1386 static SENSOR_DEVICE_ATTR(temp1_input, 0444, ds3231_hwmon_show_temp,
1387 			  NULL, 0);
1388 
1389 static struct attribute *ds3231_hwmon_attrs[] = {
1390 	&sensor_dev_attr_temp1_input.dev_attr.attr,
1391 	NULL,
1392 };
1393 ATTRIBUTE_GROUPS(ds3231_hwmon);
1394 
1395 static void ds1307_hwmon_register(struct ds1307 *ds1307)
1396 {
1397 	struct device *dev;
1398 
1399 	if (ds1307->type != ds_3231)
1400 		return;
1401 
1402 	dev = devm_hwmon_device_register_with_groups(ds1307->dev, ds1307->name,
1403 						     ds1307,
1404 						     ds3231_hwmon_groups);
1405 	if (IS_ERR(dev)) {
1406 		dev_warn(ds1307->dev, "unable to register hwmon device %ld\n",
1407 			 PTR_ERR(dev));
1408 	}
1409 }
1410 
1411 #else
1412 
1413 static void ds1307_hwmon_register(struct ds1307 *ds1307)
1414 {
1415 }
1416 
1417 #endif /* IS_REACHABLE(CONFIG_HWMON) */
1418 
1419 /*----------------------------------------------------------------------*/
1420 
1421 /*
1422  * Square-wave output support for DS3231
1423  * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS3231.pdf
1424  */
1425 #ifdef CONFIG_COMMON_CLK
1426 
1427 enum {
1428 	DS3231_CLK_SQW = 0,
1429 	DS3231_CLK_32KHZ,
1430 };
1431 
1432 #define clk_sqw_to_ds1307(clk)	\
1433 	container_of(clk, struct ds1307, clks[DS3231_CLK_SQW])
1434 #define clk_32khz_to_ds1307(clk)	\
1435 	container_of(clk, struct ds1307, clks[DS3231_CLK_32KHZ])
1436 
1437 static int ds3231_clk_sqw_rates[] = {
1438 	1,
1439 	1024,
1440 	4096,
1441 	8192,
1442 };
1443 
1444 static int ds1337_write_control(struct ds1307 *ds1307, u8 mask, u8 value)
1445 {
1446 	struct mutex *lock = &ds1307->rtc->ops_lock;
1447 	int ret;
1448 
1449 	mutex_lock(lock);
1450 	ret = regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
1451 				 mask, value);
1452 	mutex_unlock(lock);
1453 
1454 	return ret;
1455 }
1456 
1457 static unsigned long ds3231_clk_sqw_recalc_rate(struct clk_hw *hw,
1458 						unsigned long parent_rate)
1459 {
1460 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1461 	int control, ret;
1462 	int rate_sel = 0;
1463 
1464 	ret = regmap_read(ds1307->regmap, DS1337_REG_CONTROL, &control);
1465 	if (ret)
1466 		return ret;
1467 	if (control & DS1337_BIT_RS1)
1468 		rate_sel += 1;
1469 	if (control & DS1337_BIT_RS2)
1470 		rate_sel += 2;
1471 
1472 	return ds3231_clk_sqw_rates[rate_sel];
1473 }
1474 
1475 static int ds3231_clk_sqw_determine_rate(struct clk_hw *hw,
1476 					 struct clk_rate_request *req)
1477 {
1478 	int i;
1479 
1480 	for (i = ARRAY_SIZE(ds3231_clk_sqw_rates) - 1; i >= 0; i--) {
1481 		if (ds3231_clk_sqw_rates[i] <= req->rate) {
1482 			req->rate = ds3231_clk_sqw_rates[i];
1483 
1484 			return 0;
1485 		}
1486 	}
1487 
1488 	req->rate = ds3231_clk_sqw_rates[ARRAY_SIZE(ds3231_clk_sqw_rates) - 1];
1489 
1490 	return 0;
1491 }
1492 
1493 static int ds3231_clk_sqw_set_rate(struct clk_hw *hw, unsigned long rate,
1494 				   unsigned long parent_rate)
1495 {
1496 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1497 	int control = 0;
1498 	int rate_sel;
1499 
1500 	for (rate_sel = 0; rate_sel < ARRAY_SIZE(ds3231_clk_sqw_rates);
1501 			rate_sel++) {
1502 		if (ds3231_clk_sqw_rates[rate_sel] == rate)
1503 			break;
1504 	}
1505 
1506 	if (rate_sel == ARRAY_SIZE(ds3231_clk_sqw_rates))
1507 		return -EINVAL;
1508 
1509 	if (rate_sel & 1)
1510 		control |= DS1337_BIT_RS1;
1511 	if (rate_sel & 2)
1512 		control |= DS1337_BIT_RS2;
1513 
1514 	return ds1337_write_control(ds1307, DS1337_BIT_RS1 | DS1337_BIT_RS2,
1515 				control);
1516 }
1517 
1518 static int ds3231_clk_sqw_prepare(struct clk_hw *hw)
1519 {
1520 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1521 
1522 	return ds1337_write_control(ds1307, DS1337_BIT_INTCN, 0);
1523 }
1524 
1525 static void ds3231_clk_sqw_unprepare(struct clk_hw *hw)
1526 {
1527 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1528 
1529 	ds1337_write_control(ds1307, DS1337_BIT_INTCN, DS1337_BIT_INTCN);
1530 }
1531 
1532 static int ds3231_clk_sqw_is_prepared(struct clk_hw *hw)
1533 {
1534 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1535 	int control, ret;
1536 
1537 	ret = regmap_read(ds1307->regmap, DS1337_REG_CONTROL, &control);
1538 	if (ret)
1539 		return ret;
1540 
1541 	return !(control & DS1337_BIT_INTCN);
1542 }
1543 
1544 static const struct clk_ops ds3231_clk_sqw_ops = {
1545 	.prepare = ds3231_clk_sqw_prepare,
1546 	.unprepare = ds3231_clk_sqw_unprepare,
1547 	.is_prepared = ds3231_clk_sqw_is_prepared,
1548 	.recalc_rate = ds3231_clk_sqw_recalc_rate,
1549 	.determine_rate = ds3231_clk_sqw_determine_rate,
1550 	.set_rate = ds3231_clk_sqw_set_rate,
1551 };
1552 
1553 static unsigned long ds3231_clk_32khz_recalc_rate(struct clk_hw *hw,
1554 						  unsigned long parent_rate)
1555 {
1556 	return 32768;
1557 }
1558 
1559 static int ds3231_clk_32khz_control(struct ds1307 *ds1307, bool enable)
1560 {
1561 	struct mutex *lock = &ds1307->rtc->ops_lock;
1562 	int ret;
1563 
1564 	mutex_lock(lock);
1565 	ret = regmap_update_bits(ds1307->regmap, DS1337_REG_STATUS,
1566 				 DS3231_BIT_EN32KHZ,
1567 				 enable ? DS3231_BIT_EN32KHZ : 0);
1568 	mutex_unlock(lock);
1569 
1570 	return ret;
1571 }
1572 
1573 static int ds3231_clk_32khz_prepare(struct clk_hw *hw)
1574 {
1575 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1576 
1577 	return ds3231_clk_32khz_control(ds1307, true);
1578 }
1579 
1580 static void ds3231_clk_32khz_unprepare(struct clk_hw *hw)
1581 {
1582 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1583 
1584 	ds3231_clk_32khz_control(ds1307, false);
1585 }
1586 
1587 static int ds3231_clk_32khz_is_prepared(struct clk_hw *hw)
1588 {
1589 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1590 	int status, ret;
1591 
1592 	ret = regmap_read(ds1307->regmap, DS1337_REG_STATUS, &status);
1593 	if (ret)
1594 		return ret;
1595 
1596 	return !!(status & DS3231_BIT_EN32KHZ);
1597 }
1598 
1599 static const struct clk_ops ds3231_clk_32khz_ops = {
1600 	.prepare = ds3231_clk_32khz_prepare,
1601 	.unprepare = ds3231_clk_32khz_unprepare,
1602 	.is_prepared = ds3231_clk_32khz_is_prepared,
1603 	.recalc_rate = ds3231_clk_32khz_recalc_rate,
1604 };
1605 
1606 static const char *ds3231_clks_names[] = {
1607 	[DS3231_CLK_SQW] = "ds3231_clk_sqw",
1608 	[DS3231_CLK_32KHZ] = "ds3231_clk_32khz",
1609 };
1610 
1611 static struct clk_init_data ds3231_clks_init[] = {
1612 	[DS3231_CLK_SQW] = {
1613 		.ops = &ds3231_clk_sqw_ops,
1614 	},
1615 	[DS3231_CLK_32KHZ] = {
1616 		.ops = &ds3231_clk_32khz_ops,
1617 	},
1618 };
1619 
1620 static int ds3231_clks_register(struct ds1307 *ds1307)
1621 {
1622 	struct device_node *node = ds1307->dev->of_node;
1623 	struct clk_onecell_data	*onecell;
1624 	int i;
1625 
1626 	onecell = devm_kzalloc(ds1307->dev, sizeof(*onecell), GFP_KERNEL);
1627 	if (!onecell)
1628 		return -ENOMEM;
1629 
1630 	onecell->clk_num = ARRAY_SIZE(ds3231_clks_init);
1631 	onecell->clks = devm_kcalloc(ds1307->dev, onecell->clk_num,
1632 				     sizeof(onecell->clks[0]), GFP_KERNEL);
1633 	if (!onecell->clks)
1634 		return -ENOMEM;
1635 
1636 	/* optional override of the clockname */
1637 	device_property_read_string_array(ds1307->dev, "clock-output-names",
1638 					  ds3231_clks_names,
1639 					  ARRAY_SIZE(ds3231_clks_names));
1640 
1641 	for (i = 0; i < ARRAY_SIZE(ds3231_clks_init); i++) {
1642 		struct clk_init_data init = ds3231_clks_init[i];
1643 
1644 		/*
1645 		 * Interrupt signal due to alarm conditions and square-wave
1646 		 * output share same pin, so don't initialize both.
1647 		 */
1648 		if (i == DS3231_CLK_SQW && test_bit(RTC_FEATURE_ALARM, ds1307->rtc->features))
1649 			continue;
1650 
1651 		init.name = ds3231_clks_names[i];
1652 		ds1307->clks[i].init = &init;
1653 
1654 		onecell->clks[i] = devm_clk_register(ds1307->dev,
1655 						     &ds1307->clks[i]);
1656 		if (IS_ERR(onecell->clks[i]))
1657 			return PTR_ERR(onecell->clks[i]);
1658 	}
1659 
1660 	if (node)
1661 		of_clk_add_provider(node, of_clk_src_onecell_get, onecell);
1662 
1663 	return 0;
1664 }
1665 
1666 /* ds1307 RTC clock output support */
1667 static unsigned long ds1307_clk_rates[] = {
1668 	1,
1669 	4096,
1670 	8192,
1671 	32768,
1672 };
1673 
1674 static unsigned long ds1307_clk_sqw_recalc_rate(struct clk_hw *hw,
1675 						  unsigned long parent_rate)
1676 {
1677 	int ret;
1678 	unsigned int rate_id;
1679 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1680 
1681 	ret = regmap_read(ds1307->regmap, DS1307_REG_CONTROL, &rate_id);
1682 	if (ret)
1683 		return ret;
1684 
1685 	rate_id &= (DS1307_BIT_RS1 | DS1307_BIT_RS0);
1686 
1687 	return ds1307_clk_rates[rate_id];
1688 }
1689 
1690 static int ds1307_clk_sqw_determine_rate(struct clk_hw *hw,
1691 					 struct clk_rate_request *req)
1692 {
1693 	int i;
1694 
1695 	for (i = 0; i < ARRAY_SIZE(ds1307_clk_rates); i++) {
1696 		if (req->rate <= ds1307_clk_rates[i]) {
1697 			req->rate = ds1307_clk_rates[i];
1698 			return 0;
1699 		}
1700 	}
1701 
1702 	/* Default rate 1Hz */
1703 	req->rate = ds1307_clk_rates[0];
1704 
1705 	return 0;
1706 }
1707 
1708 static int ds1307_clk_sqw_set_rate(struct clk_hw *hw, unsigned long rate,
1709 				   unsigned long parent_rate)
1710 {
1711 	int id, ret;
1712 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1713 
1714 	for (id = 0; id < ARRAY_SIZE(ds1307_clk_rates); id++) {
1715 		if (ds1307_clk_rates[id] == rate)
1716 			break;
1717 	}
1718 
1719 	if (id >= ARRAY_SIZE(ds1307_clk_rates))
1720 		return -EINVAL;
1721 
1722 	ret = regmap_update_bits(ds1307->regmap, DS1307_REG_CONTROL,
1723 				 DS1307_BIT_RS0 | DS1307_BIT_RS1, id);
1724 
1725 	return ret;
1726 }
1727 
1728 static int ds1307_clk_sqw_prepare(struct clk_hw *hw)
1729 {
1730 	int ret;
1731 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1732 
1733 	ret = regmap_update_bits(ds1307->regmap, DS1307_REG_CONTROL,
1734 				 DS1307_BIT_SQWE, DS1307_BIT_SQWE);
1735 
1736 	return ret;
1737 }
1738 
1739 static void ds1307_clk_sqw_unprepare(struct clk_hw *hw)
1740 {
1741 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1742 
1743 	regmap_update_bits(ds1307->regmap, DS1307_REG_CONTROL,
1744 			   DS1307_BIT_SQWE, ~DS1307_BIT_SQWE);
1745 }
1746 
1747 static int ds1307_clk_sqw_is_prepared(struct clk_hw *hw)
1748 {
1749 	int ret;
1750 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1751 	unsigned int status;
1752 
1753 	ret = regmap_read(ds1307->regmap, DS1307_REG_CONTROL, &status);
1754 	if (ret)
1755 		return ret;
1756 
1757 	return !!(status & DS1307_BIT_SQWE);
1758 }
1759 
1760 static const struct clk_ops ds1307_clk_sqw_ops = {
1761 	.prepare = ds1307_clk_sqw_prepare,
1762 	.unprepare = ds1307_clk_sqw_unprepare,
1763 	.is_prepared = ds1307_clk_sqw_is_prepared,
1764 	.recalc_rate = ds1307_clk_sqw_recalc_rate,
1765 	.set_rate = ds1307_clk_sqw_set_rate,
1766 	.determine_rate = ds1307_clk_sqw_determine_rate,
1767 };
1768 
1769 static int rtc_ds1307_clks_register(struct ds1307 *ds1307)
1770 {
1771 	struct device_node *node = ds1307->dev->of_node;
1772 	struct clk *clk;
1773 	struct clk_init_data init = {0};
1774 
1775 	init.name = "ds1307_clk_sqw";
1776 	init.ops = &ds1307_clk_sqw_ops;
1777 
1778 	ds1307->clks[0].init = &init;
1779 
1780 	/* Register the clock with CCF */
1781 	clk = devm_clk_register(ds1307->dev, &ds1307->clks[0]);
1782 	if (IS_ERR(clk))
1783 		return PTR_ERR(clk);
1784 
1785 	if (node)
1786 		of_clk_add_provider(node, of_clk_src_simple_get, clk);
1787 
1788 	return 0;
1789 }
1790 
1791 static void ds1307_clks_register(struct ds1307 *ds1307)
1792 {
1793 	int ret;
1794 
1795 	switch (ds1307->type) {
1796 	case ds_3231:
1797 		ret = ds3231_clks_register(ds1307);
1798 		break;
1799 
1800 	case ds_1307:
1801 		ret = rtc_ds1307_clks_register(ds1307);
1802 		break;
1803 
1804 	default:
1805 		return;
1806 	}
1807 
1808 	if (ret) {
1809 		dev_warn(ds1307->dev, "unable to register clock device %d\n",
1810 			 ret);
1811 	}
1812 
1813 }
1814 
1815 #else
1816 
1817 static void ds1307_clks_register(struct ds1307 *ds1307)
1818 {
1819 }
1820 
1821 #endif /* CONFIG_COMMON_CLK */
1822 
1823 #ifdef CONFIG_WATCHDOG_CORE
1824 static const struct watchdog_info ds1388_wdt_info = {
1825 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
1826 	.identity = "DS1388 watchdog",
1827 };
1828 
1829 static const struct watchdog_ops ds1388_wdt_ops = {
1830 	.owner = THIS_MODULE,
1831 	.start = ds1388_wdt_start,
1832 	.stop = ds1388_wdt_stop,
1833 	.ping = ds1388_wdt_ping,
1834 	.set_timeout = ds1388_wdt_set_timeout,
1835 
1836 };
1837 
1838 static void ds1307_wdt_register(struct ds1307 *ds1307)
1839 {
1840 	struct watchdog_device	*wdt;
1841 	int err;
1842 	int val;
1843 
1844 	if (ds1307->type != ds_1388)
1845 		return;
1846 
1847 	wdt = devm_kzalloc(ds1307->dev, sizeof(*wdt), GFP_KERNEL);
1848 	if (!wdt)
1849 		return;
1850 
1851 	err = regmap_read(ds1307->regmap, DS1388_REG_FLAG, &val);
1852 	if (!err && val & DS1388_BIT_WF)
1853 		wdt->bootstatus = WDIOF_CARDRESET;
1854 
1855 	wdt->info = &ds1388_wdt_info;
1856 	wdt->ops = &ds1388_wdt_ops;
1857 	wdt->timeout = 99;
1858 	wdt->max_timeout = 99;
1859 	wdt->min_timeout = 1;
1860 
1861 	watchdog_init_timeout(wdt, 0, ds1307->dev);
1862 	watchdog_set_drvdata(wdt, ds1307);
1863 	devm_watchdog_register_device(ds1307->dev, wdt);
1864 }
1865 #else
1866 static void ds1307_wdt_register(struct ds1307 *ds1307)
1867 {
1868 }
1869 #endif /* CONFIG_WATCHDOG_CORE */
1870 
1871 static const struct regmap_config regmap_config = {
1872 	.reg_bits = 8,
1873 	.val_bits = 8,
1874 };
1875 
1876 static int ds1307_probe(struct i2c_client *client)
1877 {
1878 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
1879 	struct ds1307		*ds1307;
1880 	const void		*match;
1881 	int			err = -ENODEV;
1882 	int			tmp;
1883 	const struct chip_desc	*chip;
1884 	bool			want_irq;
1885 	bool			ds1307_can_wakeup_device = false;
1886 	unsigned char		regs[8];
1887 	struct ds1307_platform_data *pdata = dev_get_platdata(&client->dev);
1888 	u8			trickle_charger_setup = 0;
1889 
1890 	ds1307 = devm_kzalloc(&client->dev, sizeof(struct ds1307), GFP_KERNEL);
1891 	if (!ds1307)
1892 		return -ENOMEM;
1893 
1894 	dev_set_drvdata(&client->dev, ds1307);
1895 	ds1307->dev = &client->dev;
1896 	ds1307->name = client->name;
1897 
1898 	ds1307->regmap = devm_regmap_init_i2c(client, &regmap_config);
1899 	if (IS_ERR(ds1307->regmap)) {
1900 		dev_err(ds1307->dev, "regmap allocation failed\n");
1901 		return PTR_ERR(ds1307->regmap);
1902 	}
1903 
1904 	i2c_set_clientdata(client, ds1307);
1905 
1906 	match = device_get_match_data(&client->dev);
1907 	if (match) {
1908 		ds1307->type = (uintptr_t)match;
1909 		chip = &chips[ds1307->type];
1910 	} else if (id) {
1911 		chip = &chips[id->driver_data];
1912 		ds1307->type = id->driver_data;
1913 	} else {
1914 		return -ENODEV;
1915 	}
1916 
1917 	want_irq = client->irq > 0 && chip->alarm;
1918 
1919 	if (!pdata)
1920 		trickle_charger_setup = ds1307_trickle_init(ds1307, chip);
1921 	else if (pdata->trickle_charger_setup)
1922 		trickle_charger_setup = pdata->trickle_charger_setup;
1923 
1924 	if (trickle_charger_setup && chip->trickle_charger_reg) {
1925 		dev_dbg(ds1307->dev,
1926 			"writing trickle charger info 0x%x to 0x%x\n",
1927 			trickle_charger_setup, chip->trickle_charger_reg);
1928 		regmap_write(ds1307->regmap, chip->trickle_charger_reg,
1929 			     trickle_charger_setup);
1930 	}
1931 
1932 /*
1933  * For devices with no IRQ directly connected to the SoC, the RTC chip
1934  * can be forced as a wakeup source by stating that explicitly in
1935  * the device's .dts file using the "wakeup-source" boolean property.
1936  * If the "wakeup-source" property is set, don't request an IRQ.
1937  * This will guarantee the 'wakealarm' sysfs entry is available on the device,
1938  * if supported by the RTC.
1939  */
1940 	if (chip->alarm && device_property_read_bool(&client->dev, "wakeup-source"))
1941 		ds1307_can_wakeup_device = true;
1942 
1943 	switch (ds1307->type) {
1944 	case ds_1337:
1945 	case ds_1339:
1946 	case ds_1341:
1947 	case ds_3231:
1948 		/* get registers that the "rtc" read below won't read... */
1949 		err = regmap_bulk_read(ds1307->regmap, DS1337_REG_CONTROL,
1950 				       regs, 2);
1951 		if (err) {
1952 			dev_dbg(ds1307->dev, "read error %d\n", err);
1953 			goto exit;
1954 		}
1955 
1956 		/* oscillator off?  turn it on, so clock can tick. */
1957 		if (regs[0] & DS1337_BIT_nEOSC)
1958 			regs[0] &= ~DS1337_BIT_nEOSC;
1959 
1960 		/*
1961 		 * Using IRQ or defined as wakeup-source?
1962 		 * Disable the square wave and both alarms.
1963 		 * For some variants, be sure alarms can trigger when we're
1964 		 * running on Vbackup (BBSQI/BBSQW)
1965 		 */
1966 		if (want_irq || ds1307_can_wakeup_device)
1967 			regs[0] |= DS1337_BIT_INTCN | chip->bbsqi_bit;
1968 
1969 		regmap_write(ds1307->regmap, DS1337_REG_CONTROL,
1970 			     regs[0]);
1971 
1972 		/* oscillator fault? warn */
1973 		if (regs[1] & DS1337_BIT_OSF) {
1974 			dev_warn(ds1307->dev, "SET TIME!\n");
1975 		}
1976 		break;
1977 
1978 	case rx_8025:
1979 		err = regmap_bulk_read(ds1307->regmap,
1980 				       RX8025_REG_CTRL1 << 4 | 0x08, regs, 2);
1981 		if (err) {
1982 			dev_dbg(ds1307->dev, "read error %d\n", err);
1983 			goto exit;
1984 		}
1985 
1986 		/* oscillator off?  turn it on, so clock can tick. */
1987 		if (!(regs[1] & RX8025_BIT_XST)) {
1988 			regs[1] |= RX8025_BIT_XST;
1989 			regmap_write(ds1307->regmap,
1990 				     RX8025_REG_CTRL2 << 4 | 0x08,
1991 				     regs[1]);
1992 			dev_warn(ds1307->dev,
1993 				 "oscillator stop detected - SET TIME!\n");
1994 		}
1995 
1996 		if (regs[1] & RX8025_BIT_PON) {
1997 			regs[1] &= ~RX8025_BIT_PON;
1998 			regmap_write(ds1307->regmap,
1999 				     RX8025_REG_CTRL2 << 4 | 0x08,
2000 				     regs[1]);
2001 			dev_warn(ds1307->dev, "power-on detected\n");
2002 		}
2003 
2004 		if (regs[1] & RX8025_BIT_VDET) {
2005 			regs[1] &= ~RX8025_BIT_VDET;
2006 			regmap_write(ds1307->regmap,
2007 				     RX8025_REG_CTRL2 << 4 | 0x08,
2008 				     regs[1]);
2009 			dev_warn(ds1307->dev, "voltage drop detected\n");
2010 		}
2011 
2012 		/* make sure we are running in 24hour mode */
2013 		if (!(regs[0] & RX8025_BIT_2412)) {
2014 			u8 hour;
2015 
2016 			/* switch to 24 hour mode */
2017 			regmap_write(ds1307->regmap,
2018 				     RX8025_REG_CTRL1 << 4 | 0x08,
2019 				     regs[0] | RX8025_BIT_2412);
2020 
2021 			err = regmap_bulk_read(ds1307->regmap,
2022 					       RX8025_REG_CTRL1 << 4 | 0x08,
2023 					       regs, 2);
2024 			if (err) {
2025 				dev_dbg(ds1307->dev, "read error %d\n", err);
2026 				goto exit;
2027 			}
2028 
2029 			/* correct hour */
2030 			hour = bcd2bin(regs[DS1307_REG_HOUR]);
2031 			if (hour == 12)
2032 				hour = 0;
2033 			if (regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
2034 				hour += 12;
2035 
2036 			regmap_write(ds1307->regmap,
2037 				     DS1307_REG_HOUR << 4 | 0x08, hour);
2038 		}
2039 		break;
2040 	case ds_1388:
2041 		err = regmap_read(ds1307->regmap, DS1388_REG_CONTROL, &tmp);
2042 		if (err) {
2043 			dev_dbg(ds1307->dev, "read error %d\n", err);
2044 			goto exit;
2045 		}
2046 
2047 		/* oscillator off?  turn it on, so clock can tick. */
2048 		if (tmp & DS1388_BIT_nEOSC) {
2049 			tmp &= ~DS1388_BIT_nEOSC;
2050 			regmap_write(ds1307->regmap, DS1388_REG_CONTROL, tmp);
2051 		}
2052 		break;
2053 	default:
2054 		break;
2055 	}
2056 
2057 	/* read RTC registers */
2058 	err = regmap_bulk_read(ds1307->regmap, chip->offset, regs,
2059 			       sizeof(regs));
2060 	if (err) {
2061 		dev_dbg(ds1307->dev, "read error %d\n", err);
2062 		goto exit;
2063 	}
2064 
2065 	if (ds1307->type == mcp794xx &&
2066 	    !(regs[DS1307_REG_WDAY] & MCP794XX_BIT_VBATEN)) {
2067 		regmap_write(ds1307->regmap, DS1307_REG_WDAY,
2068 			     regs[DS1307_REG_WDAY] |
2069 			     MCP794XX_BIT_VBATEN);
2070 	}
2071 
2072 	tmp = regs[DS1307_REG_HOUR];
2073 	switch (ds1307->type) {
2074 	case ds_1340:
2075 	case m41t0:
2076 	case m41t00:
2077 	case m41t11:
2078 		/*
2079 		 * NOTE: ignores century bits; fix before deploying
2080 		 * systems that will run through year 2100.
2081 		 */
2082 		break;
2083 	case rx_8025:
2084 		break;
2085 	default:
2086 		if (!(tmp & DS1307_BIT_12HR))
2087 			break;
2088 
2089 		/*
2090 		 * Be sure we're in 24 hour mode.  Multi-master systems
2091 		 * take note...
2092 		 */
2093 		tmp = bcd2bin(tmp & 0x1f);
2094 		if (tmp == 12)
2095 			tmp = 0;
2096 		if (regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
2097 			tmp += 12;
2098 		regmap_write(ds1307->regmap, chip->offset + DS1307_REG_HOUR,
2099 			     bin2bcd(tmp));
2100 	}
2101 
2102 	ds1307->rtc = devm_rtc_allocate_device(ds1307->dev);
2103 	if (IS_ERR(ds1307->rtc))
2104 		return PTR_ERR(ds1307->rtc);
2105 
2106 	if (want_irq || ds1307_can_wakeup_device)
2107 		device_set_wakeup_capable(ds1307->dev, true);
2108 	else
2109 		clear_bit(RTC_FEATURE_ALARM, ds1307->rtc->features);
2110 
2111 	if (ds1307_can_wakeup_device && !want_irq) {
2112 		dev_info(ds1307->dev,
2113 			 "'wakeup-source' is set, request for an IRQ is disabled!\n");
2114 		/* We cannot support UIE mode if we do not have an IRQ line */
2115 		clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, ds1307->rtc->features);
2116 	}
2117 
2118 	if (want_irq) {
2119 		err = devm_request_threaded_irq(ds1307->dev, client->irq, NULL,
2120 						chip->irq_handler ?: ds1307_irq,
2121 						IRQF_SHARED | IRQF_ONESHOT,
2122 						ds1307->name, ds1307);
2123 		if (err) {
2124 			client->irq = 0;
2125 			device_set_wakeup_capable(ds1307->dev, false);
2126 			clear_bit(RTC_FEATURE_ALARM, ds1307->rtc->features);
2127 			dev_err(ds1307->dev, "unable to request IRQ!\n");
2128 		} else {
2129 			dev_dbg(ds1307->dev, "got IRQ %d\n", client->irq);
2130 		}
2131 	}
2132 
2133 	ds1307->rtc->ops = chip->rtc_ops ?: &ds13xx_rtc_ops;
2134 	err = ds1307_add_frequency_test(ds1307);
2135 	if (err)
2136 		return err;
2137 
2138 	err = devm_rtc_register_device(ds1307->rtc);
2139 	if (err)
2140 		return err;
2141 
2142 	if (chip->nvram_size) {
2143 		struct nvmem_config nvmem_cfg = {
2144 			.name = "ds1307_nvram",
2145 			.word_size = 1,
2146 			.stride = 1,
2147 			.size = chip->nvram_size,
2148 			.reg_read = ds1307_nvram_read,
2149 			.reg_write = ds1307_nvram_write,
2150 			.priv = ds1307,
2151 		};
2152 
2153 		devm_rtc_nvmem_register(ds1307->rtc, &nvmem_cfg);
2154 	}
2155 
2156 	ds1307_hwmon_register(ds1307);
2157 	ds1307_clks_register(ds1307);
2158 	ds1307_wdt_register(ds1307);
2159 
2160 	return 0;
2161 
2162 exit:
2163 	return err;
2164 }
2165 
2166 static struct i2c_driver ds1307_driver = {
2167 	.driver = {
2168 		.name	= "rtc-ds1307",
2169 		.of_match_table = ds1307_of_match,
2170 	},
2171 	.probe		= ds1307_probe,
2172 	.id_table	= ds1307_id,
2173 };
2174 
2175 module_i2c_driver(ds1307_driver);
2176 
2177 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
2178 MODULE_LICENSE("GPL");
2179