xref: /linux/drivers/rtc/rtc-ds1307.c (revision c118478665f467e57d06b2354de65974b246b82b)
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/mod_devicetable.h>
16 #include <linux/module.h>
17 #include <linux/property.h>
18 #include <linux/rtc/ds1307.h>
19 #include <linux/rtc.h>
20 #include <linux/slab.h>
21 #include <linux/string.h>
22 #include <linux/hwmon.h>
23 #include <linux/hwmon-sysfs.h>
24 #include <linux/clk-provider.h>
25 #include <linux/regmap.h>
26 #include <linux/watchdog.h>
27 
28 /*
29  * We can't determine type by probing, but if we expect pre-Linux code
30  * to have set the chip up as a clock (turning on the oscillator and
31  * setting the date and time), Linux can ignore the non-clock features.
32  * That's a natural job for a factory or repair bench.
33  */
34 enum ds_type {
35 	unknown_ds_type, /* always first and 0 */
36 	ds_1307,
37 	ds_1308,
38 	ds_1337,
39 	ds_1338,
40 	ds_1339,
41 	ds_1340,
42 	ds_1341,
43 	ds_1388,
44 	ds_3231,
45 	m41t0,
46 	m41t00,
47 	m41t11,
48 	mcp794xx,
49 	rx_8025,
50 	rx_8130,
51 	last_ds_type /* always last */
52 	/* rs5c372 too?  different address... */
53 };
54 
55 /* RTC registers don't differ much, except for the century flag */
56 #define DS1307_REG_SECS		0x00	/* 00-59 */
57 #	define DS1307_BIT_CH		0x80
58 #	define DS1340_BIT_nEOSC		0x80
59 #	define MCP794XX_BIT_ST		0x80
60 #define DS1307_REG_MIN		0x01	/* 00-59 */
61 #	define M41T0_BIT_OF		0x80
62 #define DS1307_REG_HOUR		0x02	/* 00-23, or 1-12{am,pm} */
63 #	define DS1307_BIT_12HR		0x40	/* in REG_HOUR */
64 #	define DS1307_BIT_PM		0x20	/* in REG_HOUR */
65 #	define DS1340_BIT_CENTURY_EN	0x80	/* in REG_HOUR */
66 #	define DS1340_BIT_CENTURY	0x40	/* in REG_HOUR */
67 #define DS1307_REG_WDAY		0x03	/* 01-07 */
68 #	define MCP794XX_BIT_OSCRUN	BIT(5)
69 #	define MCP794XX_BIT_VBATEN	0x08
70 #define DS1307_REG_MDAY		0x04	/* 01-31 */
71 #define DS1307_REG_MONTH	0x05	/* 01-12 */
72 #	define DS1337_BIT_CENTURY	0x80	/* in REG_MONTH */
73 #define DS1307_REG_YEAR		0x06	/* 00-99 */
74 
75 /*
76  * Other registers (control, status, alarms, trickle charge, NVRAM, etc)
77  * start at 7, and they differ a LOT. Only control and status matter for
78  * basic RTC date and time functionality; be careful using them.
79  */
80 #define DS1307_REG_CONTROL	0x07		/* or ds1338 */
81 #	define DS1307_BIT_OUT		0x80
82 #	define DS1338_BIT_OSF		0x20
83 #	define DS1307_BIT_SQWE		0x10
84 #	define DS1307_BIT_RS1		0x02
85 #	define DS1307_BIT_RS0		0x01
86 #define DS1337_REG_CONTROL	0x0e
87 #	define DS1337_BIT_nEOSC		0x80
88 #	define DS1339_BIT_BBSQI		0x20
89 #	define DS3231_BIT_BBSQW		0x40 /* same as BBSQI */
90 #	define DS1337_BIT_RS2		0x10
91 #	define DS1337_BIT_RS1		0x08
92 #	define DS1337_BIT_INTCN		0x04
93 #	define DS1337_BIT_A2IE		0x02
94 #	define DS1337_BIT_A1IE		0x01
95 #define DS1340_REG_CONTROL	0x07
96 #	define DS1340_BIT_OUT		0x80
97 #	define DS1340_BIT_FT		0x40
98 #	define DS1340_BIT_CALIB_SIGN	0x20
99 #	define DS1340_M_CALIBRATION	0x1f
100 #define DS1340_REG_FLAG		0x09
101 #	define DS1340_BIT_OSF		0x80
102 #define DS1337_REG_STATUS	0x0f
103 #	define DS1337_BIT_OSF		0x80
104 #	define DS3231_BIT_EN32KHZ	0x08
105 #	define DS1337_BIT_A2I		0x02
106 #	define DS1337_BIT_A1I		0x01
107 #define DS1339_REG_ALARM1_SECS	0x07
108 
109 #define DS13XX_TRICKLE_CHARGER_MAGIC	0xa0
110 
111 #define RX8025_REG_CTRL1	0x0e
112 #	define RX8025_BIT_2412		0x20
113 #define RX8025_REG_CTRL2	0x0f
114 #	define RX8025_BIT_PON		0x10
115 #	define RX8025_BIT_VDET		0x40
116 #	define RX8025_BIT_XST		0x20
117 
118 #define RX8130_REG_ALARM_MIN		0x17
119 #define RX8130_REG_ALARM_HOUR		0x18
120 #define RX8130_REG_ALARM_WEEK_OR_DAY	0x19
121 #define RX8130_REG_EXTENSION		0x1c
122 #define RX8130_REG_EXTENSION_WADA	BIT(3)
123 #define RX8130_REG_FLAG			0x1d
124 #define RX8130_REG_FLAG_VLF		BIT(1)
125 #define RX8130_REG_FLAG_AF		BIT(3)
126 #define RX8130_REG_CONTROL0		0x1e
127 #define RX8130_REG_CONTROL0_AIE		BIT(3)
128 #define RX8130_REG_CONTROL1		0x1f
129 #define RX8130_REG_CONTROL1_INIEN	BIT(4)
130 #define RX8130_REG_CONTROL1_CHGEN	BIT(5)
131 
132 #define MCP794XX_REG_CONTROL		0x07
133 #	define MCP794XX_BIT_ALM0_EN	0x10
134 #	define MCP794XX_BIT_ALM1_EN	0x20
135 #define MCP794XX_REG_ALARM0_BASE	0x0a
136 #define MCP794XX_REG_ALARM0_CTRL	0x0d
137 #define MCP794XX_REG_ALARM1_BASE	0x11
138 #define MCP794XX_REG_ALARM1_CTRL	0x14
139 #	define MCP794XX_BIT_ALMX_IF	BIT(3)
140 #	define MCP794XX_BIT_ALMX_C0	BIT(4)
141 #	define MCP794XX_BIT_ALMX_C1	BIT(5)
142 #	define MCP794XX_BIT_ALMX_C2	BIT(6)
143 #	define MCP794XX_BIT_ALMX_POL	BIT(7)
144 #	define MCP794XX_MSK_ALMX_MATCH	(MCP794XX_BIT_ALMX_C0 | \
145 					 MCP794XX_BIT_ALMX_C1 | \
146 					 MCP794XX_BIT_ALMX_C2)
147 
148 #define M41TXX_REG_CONTROL	0x07
149 #	define M41TXX_BIT_OUT		BIT(7)
150 #	define M41TXX_BIT_FT		BIT(6)
151 #	define M41TXX_BIT_CALIB_SIGN	BIT(5)
152 #	define M41TXX_M_CALIBRATION	GENMASK(4, 0)
153 
154 #define DS1388_REG_WDOG_HUN_SECS	0x08
155 #define DS1388_REG_WDOG_SECS		0x09
156 #define DS1388_REG_FLAG			0x0b
157 #	define DS1388_BIT_WF		BIT(6)
158 #	define DS1388_BIT_OSF		BIT(7)
159 #define DS1388_REG_CONTROL		0x0c
160 #	define DS1388_BIT_RST		BIT(0)
161 #	define DS1388_BIT_WDE		BIT(1)
162 #	define DS1388_BIT_nEOSC		BIT(7)
163 
164 /* negative offset step is -2.034ppm */
165 #define M41TXX_NEG_OFFSET_STEP_PPB	2034
166 /* positive offset step is +4.068ppm */
167 #define M41TXX_POS_OFFSET_STEP_PPB	4068
168 /* Min and max values supported with 'offset' interface by M41TXX */
169 #define M41TXX_MIN_OFFSET	((-31) * M41TXX_NEG_OFFSET_STEP_PPB)
170 #define M41TXX_MAX_OFFSET	((31) * M41TXX_POS_OFFSET_STEP_PPB)
171 
172 struct ds1307 {
173 	enum ds_type		type;
174 	struct device		*dev;
175 	struct regmap		*regmap;
176 	const char		*name;
177 	struct rtc_device	*rtc;
178 #ifdef CONFIG_COMMON_CLK
179 	struct clk_hw		clks[2];
180 #endif
181 };
182 
183 struct chip_desc {
184 	unsigned		alarm:1;
185 	u16			nvram_offset;
186 	u16			nvram_size;
187 	u8			offset; /* register's offset */
188 	u8			century_reg;
189 	u8			century_enable_bit;
190 	u8			century_bit;
191 	u8			bbsqi_bit;
192 	irq_handler_t		irq_handler;
193 	const struct rtc_class_ops *rtc_ops;
194 	u16			trickle_charger_reg;
195 	u8			(*do_trickle_setup)(struct ds1307 *, u32,
196 						    bool);
197 	/* Does the RTC require trickle-resistor-ohms to select the value of
198 	 * the resistor between Vcc and Vbackup?
199 	 */
200 	bool			requires_trickle_resistor;
201 	/* Some RTC's batteries and supercaps were charged by default, others
202 	 * allow charging but were not configured previously to do so.
203 	 * Remember this behavior to stay backwards compatible.
204 	 */
205 	bool			charge_default;
206 };
207 
208 static const struct chip_desc chips[last_ds_type];
209 
210 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
211 {
212 	struct ds1307	*ds1307 = dev_get_drvdata(dev);
213 	int		tmp, ret;
214 	const struct chip_desc *chip = &chips[ds1307->type];
215 	u8 regs[7];
216 
217 	if (ds1307->type == rx_8130) {
218 		unsigned int regflag;
219 		ret = regmap_read(ds1307->regmap, RX8130_REG_FLAG, &regflag);
220 		if (ret) {
221 			dev_err(dev, "%s error %d\n", "read", ret);
222 			return ret;
223 		}
224 
225 		if (regflag & RX8130_REG_FLAG_VLF) {
226 			dev_warn_once(dev, "oscillator failed, set time!\n");
227 			return -EINVAL;
228 		}
229 	}
230 
231 	/* read the RTC date and time registers all at once */
232 	ret = regmap_bulk_read(ds1307->regmap, chip->offset, regs,
233 			       sizeof(regs));
234 	if (ret) {
235 		dev_err(dev, "%s error %d\n", "read", ret);
236 		return ret;
237 	}
238 
239 	dev_dbg(dev, "%s: %7ph\n", "read", regs);
240 
241 	/* if oscillator fail bit is set, no data can be trusted */
242 	if (ds1307->type == m41t0 &&
243 	    regs[DS1307_REG_MIN] & M41T0_BIT_OF) {
244 		dev_warn_once(dev, "oscillator failed, set time!\n");
245 		return -EINVAL;
246 	} else if (ds1307->type == mcp794xx &&
247 	    !(regs[DS1307_REG_WDAY] & MCP794XX_BIT_OSCRUN)) {
248 		dev_warn_once(dev, "oscillator failed, set time!\n");
249 		return -EINVAL;
250 	}
251 
252 	tmp = regs[DS1307_REG_SECS];
253 	switch (ds1307->type) {
254 	case ds_1307:
255 	case m41t0:
256 	case m41t00:
257 	case m41t11:
258 		if (tmp & DS1307_BIT_CH)
259 			return -EINVAL;
260 		break;
261 	case ds_1308:
262 	case ds_1338:
263 		if (tmp & DS1307_BIT_CH)
264 			return -EINVAL;
265 
266 		ret = regmap_read(ds1307->regmap, DS1307_REG_CONTROL, &tmp);
267 		if (ret)
268 			return ret;
269 		if (tmp & DS1338_BIT_OSF)
270 			return -EINVAL;
271 		break;
272 	case ds_1340:
273 		if (tmp & DS1340_BIT_nEOSC)
274 			return -EINVAL;
275 
276 		ret = regmap_read(ds1307->regmap, DS1340_REG_FLAG, &tmp);
277 		if (ret)
278 			return ret;
279 		if (tmp & DS1340_BIT_OSF)
280 			return -EINVAL;
281 		break;
282 	case ds_1388:
283 		ret = regmap_read(ds1307->regmap, DS1388_REG_FLAG, &tmp);
284 		if (ret)
285 			return ret;
286 		if (tmp & DS1388_BIT_OSF)
287 			return -EINVAL;
288 		break;
289 	case mcp794xx:
290 		if (!(tmp & MCP794XX_BIT_ST))
291 			return -EINVAL;
292 
293 		break;
294 	default:
295 		break;
296 	}
297 
298 	t->tm_sec = bcd2bin(regs[DS1307_REG_SECS] & 0x7f);
299 	t->tm_min = bcd2bin(regs[DS1307_REG_MIN] & 0x7f);
300 	tmp = regs[DS1307_REG_HOUR] & 0x3f;
301 	t->tm_hour = bcd2bin(tmp);
302 	/* rx8130 is bit position, not BCD */
303 	if (ds1307->type == rx_8130)
304 		t->tm_wday = fls(regs[DS1307_REG_WDAY] & 0x7f);
305 	else
306 		t->tm_wday = bcd2bin(regs[DS1307_REG_WDAY] & 0x07) - 1;
307 	t->tm_mday = bcd2bin(regs[DS1307_REG_MDAY] & 0x3f);
308 	tmp = regs[DS1307_REG_MONTH] & 0x1f;
309 	t->tm_mon = bcd2bin(tmp) - 1;
310 	t->tm_year = bcd2bin(regs[DS1307_REG_YEAR]) + 100;
311 
312 	if (regs[chip->century_reg] & chip->century_bit &&
313 	    IS_ENABLED(CONFIG_RTC_DRV_DS1307_CENTURY))
314 		t->tm_year += 100;
315 
316 	dev_dbg(dev, "%s secs=%d, mins=%d, "
317 		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
318 		"read", t->tm_sec, t->tm_min,
319 		t->tm_hour, t->tm_mday,
320 		t->tm_mon, t->tm_year, t->tm_wday);
321 
322 	return 0;
323 }
324 
325 static int ds1307_set_time(struct device *dev, struct rtc_time *t)
326 {
327 	struct ds1307	*ds1307 = dev_get_drvdata(dev);
328 	const struct chip_desc *chip = &chips[ds1307->type];
329 	int		result;
330 	int		tmp;
331 	u8		regs[7];
332 
333 	dev_dbg(dev, "%s secs=%d, mins=%d, "
334 		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
335 		"write", t->tm_sec, t->tm_min,
336 		t->tm_hour, t->tm_mday,
337 		t->tm_mon, t->tm_year, t->tm_wday);
338 
339 	if (t->tm_year < 100)
340 		return -EINVAL;
341 
342 #ifdef CONFIG_RTC_DRV_DS1307_CENTURY
343 	if (t->tm_year > (chip->century_bit ? 299 : 199))
344 		return -EINVAL;
345 #else
346 	if (t->tm_year > 199)
347 		return -EINVAL;
348 #endif
349 
350 	regs[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
351 	regs[DS1307_REG_MIN] = bin2bcd(t->tm_min);
352 	regs[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
353 	/* rx8130 is bit position, not BCD */
354 	if (ds1307->type == rx_8130)
355 		regs[DS1307_REG_WDAY] = 1 << t->tm_wday;
356 	else
357 		regs[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
358 	regs[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
359 	regs[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
360 
361 	/* assume 20YY not 19YY */
362 	tmp = t->tm_year % 100;
363 	regs[DS1307_REG_YEAR] = bin2bcd(tmp);
364 
365 	if (chip->century_enable_bit)
366 		regs[chip->century_reg] |= chip->century_enable_bit;
367 	if (t->tm_year > 199 && chip->century_bit)
368 		regs[chip->century_reg] |= chip->century_bit;
369 
370 	switch (ds1307->type) {
371 	case ds_1308:
372 	case ds_1338:
373 		regmap_update_bits(ds1307->regmap, DS1307_REG_CONTROL,
374 				   DS1338_BIT_OSF, 0);
375 		break;
376 	case ds_1340:
377 		regmap_update_bits(ds1307->regmap, DS1340_REG_FLAG,
378 				   DS1340_BIT_OSF, 0);
379 		break;
380 	case ds_1388:
381 		regmap_update_bits(ds1307->regmap, DS1388_REG_FLAG,
382 				   DS1388_BIT_OSF, 0);
383 		break;
384 	case mcp794xx:
385 		/*
386 		 * these bits were cleared when preparing the date/time
387 		 * values and need to be set again before writing the
388 		 * regsfer out to the device.
389 		 */
390 		regs[DS1307_REG_SECS] |= MCP794XX_BIT_ST;
391 		regs[DS1307_REG_WDAY] |= MCP794XX_BIT_VBATEN;
392 		break;
393 	default:
394 		break;
395 	}
396 
397 	dev_dbg(dev, "%s: %7ph\n", "write", regs);
398 
399 	result = regmap_bulk_write(ds1307->regmap, chip->offset, regs,
400 				   sizeof(regs));
401 	if (result) {
402 		dev_err(dev, "%s error %d\n", "write", result);
403 		return result;
404 	}
405 
406 	if (ds1307->type == rx_8130) {
407 		/* clear Voltage Loss Flag as data is available now */
408 		result = regmap_write(ds1307->regmap, RX8130_REG_FLAG,
409 				      ~(u8)RX8130_REG_FLAG_VLF);
410 		if (result) {
411 			dev_err(dev, "%s error %d\n", "write", result);
412 			return result;
413 		}
414 	}
415 
416 	return 0;
417 }
418 
419 static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
420 {
421 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
422 	int			ret;
423 	u8			regs[9];
424 
425 	/* read all ALARM1, ALARM2, and status registers at once */
426 	ret = regmap_bulk_read(ds1307->regmap, DS1339_REG_ALARM1_SECS,
427 			       regs, sizeof(regs));
428 	if (ret) {
429 		dev_err(dev, "%s error %d\n", "alarm read", ret);
430 		return ret;
431 	}
432 
433 	dev_dbg(dev, "%s: %4ph, %3ph, %2ph\n", "alarm read",
434 		&regs[0], &regs[4], &regs[7]);
435 
436 	/*
437 	 * report alarm time (ALARM1); assume 24 hour and day-of-month modes,
438 	 * and that all four fields are checked matches
439 	 */
440 	t->time.tm_sec = bcd2bin(regs[0] & 0x7f);
441 	t->time.tm_min = bcd2bin(regs[1] & 0x7f);
442 	t->time.tm_hour = bcd2bin(regs[2] & 0x3f);
443 	t->time.tm_mday = bcd2bin(regs[3] & 0x3f);
444 
445 	/* ... and status */
446 	t->enabled = !!(regs[7] & DS1337_BIT_A1IE);
447 	t->pending = !!(regs[8] & DS1337_BIT_A1I);
448 
449 	dev_dbg(dev, "%s secs=%d, mins=%d, "
450 		"hours=%d, mday=%d, enabled=%d, pending=%d\n",
451 		"alarm read", t->time.tm_sec, t->time.tm_min,
452 		t->time.tm_hour, t->time.tm_mday,
453 		t->enabled, t->pending);
454 
455 	return 0;
456 }
457 
458 static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
459 {
460 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
461 	unsigned char		regs[9];
462 	u8			control, status;
463 	int			ret;
464 
465 	dev_dbg(dev, "%s secs=%d, mins=%d, "
466 		"hours=%d, mday=%d, enabled=%d, pending=%d\n",
467 		"alarm set", t->time.tm_sec, t->time.tm_min,
468 		t->time.tm_hour, t->time.tm_mday,
469 		t->enabled, t->pending);
470 
471 	/* read current status of both alarms and the chip */
472 	ret = regmap_bulk_read(ds1307->regmap, DS1339_REG_ALARM1_SECS, regs,
473 			       sizeof(regs));
474 	if (ret) {
475 		dev_err(dev, "%s error %d\n", "alarm write", ret);
476 		return ret;
477 	}
478 	control = regs[7];
479 	status = regs[8];
480 
481 	dev_dbg(dev, "%s: %4ph, %3ph, %02x %02x\n", "alarm set (old status)",
482 		&regs[0], &regs[4], control, status);
483 
484 	/* set ALARM1, using 24 hour and day-of-month modes */
485 	regs[0] = bin2bcd(t->time.tm_sec);
486 	regs[1] = bin2bcd(t->time.tm_min);
487 	regs[2] = bin2bcd(t->time.tm_hour);
488 	regs[3] = bin2bcd(t->time.tm_mday);
489 
490 	/* set ALARM2 to non-garbage */
491 	regs[4] = 0;
492 	regs[5] = 0;
493 	regs[6] = 0;
494 
495 	/* disable alarms */
496 	regs[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
497 	regs[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
498 
499 	ret = regmap_bulk_write(ds1307->regmap, DS1339_REG_ALARM1_SECS, regs,
500 				sizeof(regs));
501 	if (ret) {
502 		dev_err(dev, "can't set alarm time\n");
503 		return ret;
504 	}
505 
506 	/* optionally enable ALARM1 */
507 	if (t->enabled) {
508 		dev_dbg(dev, "alarm IRQ armed\n");
509 		regs[7] |= DS1337_BIT_A1IE;	/* only ALARM1 is used */
510 		regmap_write(ds1307->regmap, DS1337_REG_CONTROL, regs[7]);
511 	}
512 
513 	return 0;
514 }
515 
516 static int ds1307_alarm_irq_enable(struct device *dev, unsigned int enabled)
517 {
518 	struct ds1307		*ds1307 = dev_get_drvdata(dev);
519 
520 	return regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
521 				  DS1337_BIT_A1IE,
522 				  enabled ? DS1337_BIT_A1IE : 0);
523 }
524 
525 static u8 do_trickle_setup_ds1339(struct ds1307 *ds1307, u32 ohms, bool diode)
526 {
527 	u8 setup = (diode) ? DS1307_TRICKLE_CHARGER_DIODE :
528 		DS1307_TRICKLE_CHARGER_NO_DIODE;
529 
530 	setup |= DS13XX_TRICKLE_CHARGER_MAGIC;
531 
532 	switch (ohms) {
533 	case 250:
534 		setup |= DS1307_TRICKLE_CHARGER_250_OHM;
535 		break;
536 	case 2000:
537 		setup |= DS1307_TRICKLE_CHARGER_2K_OHM;
538 		break;
539 	case 4000:
540 		setup |= DS1307_TRICKLE_CHARGER_4K_OHM;
541 		break;
542 	default:
543 		dev_warn(ds1307->dev,
544 			 "Unsupported ohm value %u in dt\n", ohms);
545 		return 0;
546 	}
547 	return setup;
548 }
549 
550 static u8 do_trickle_setup_rx8130(struct ds1307 *ds1307, u32 ohms, bool diode)
551 {
552 	/* make sure that the backup battery is enabled */
553 	u8 setup = RX8130_REG_CONTROL1_INIEN;
554 	if (diode)
555 		setup |= RX8130_REG_CONTROL1_CHGEN;
556 
557 	return setup;
558 }
559 
560 static irqreturn_t rx8130_irq(int irq, void *dev_id)
561 {
562 	struct ds1307           *ds1307 = dev_id;
563 	u8 ctl[3];
564 	int ret;
565 
566 	rtc_lock(ds1307->rtc);
567 
568 	/* Read control registers. */
569 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
570 			       sizeof(ctl));
571 	if (ret < 0)
572 		goto out;
573 	if (!(ctl[1] & RX8130_REG_FLAG_AF))
574 		goto out;
575 	ctl[1] &= ~RX8130_REG_FLAG_AF;
576 	ctl[2] &= ~RX8130_REG_CONTROL0_AIE;
577 
578 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
579 				sizeof(ctl));
580 	if (ret < 0)
581 		goto out;
582 
583 	rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
584 
585 out:
586 	rtc_unlock(ds1307->rtc);
587 
588 	return IRQ_HANDLED;
589 }
590 
591 static int rx8130_read_alarm(struct device *dev, struct rtc_wkalrm *t)
592 {
593 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
594 	u8 ald[3], ctl[3];
595 	int ret;
596 
597 	/* Read alarm registers. */
598 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_ALARM_MIN, ald,
599 			       sizeof(ald));
600 	if (ret < 0)
601 		return ret;
602 
603 	/* Read control registers. */
604 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
605 			       sizeof(ctl));
606 	if (ret < 0)
607 		return ret;
608 
609 	t->enabled = !!(ctl[2] & RX8130_REG_CONTROL0_AIE);
610 	t->pending = !!(ctl[1] & RX8130_REG_FLAG_AF);
611 
612 	/* Report alarm 0 time assuming 24-hour and day-of-month modes. */
613 	t->time.tm_sec = -1;
614 	t->time.tm_min = bcd2bin(ald[0] & 0x7f);
615 	t->time.tm_hour = bcd2bin(ald[1] & 0x7f);
616 	t->time.tm_wday = -1;
617 	t->time.tm_mday = bcd2bin(ald[2] & 0x7f);
618 	t->time.tm_mon = -1;
619 	t->time.tm_year = -1;
620 	t->time.tm_yday = -1;
621 	t->time.tm_isdst = -1;
622 
623 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d enabled=%d\n",
624 		__func__, t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
625 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled);
626 
627 	return 0;
628 }
629 
630 static int rx8130_set_alarm(struct device *dev, struct rtc_wkalrm *t)
631 {
632 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
633 	u8 ald[3], ctl[3];
634 	int ret;
635 
636 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
637 		"enabled=%d pending=%d\n", __func__,
638 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
639 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
640 		t->enabled, t->pending);
641 
642 	/* Read control registers. */
643 	ret = regmap_bulk_read(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
644 			       sizeof(ctl));
645 	if (ret < 0)
646 		return ret;
647 
648 	ctl[0] &= RX8130_REG_EXTENSION_WADA;
649 	ctl[1] &= ~RX8130_REG_FLAG_AF;
650 	ctl[2] &= ~RX8130_REG_CONTROL0_AIE;
651 
652 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_EXTENSION, ctl,
653 				sizeof(ctl));
654 	if (ret < 0)
655 		return ret;
656 
657 	/* Hardware alarm precision is 1 minute! */
658 	ald[0] = bin2bcd(t->time.tm_min);
659 	ald[1] = bin2bcd(t->time.tm_hour);
660 	ald[2] = bin2bcd(t->time.tm_mday);
661 
662 	ret = regmap_bulk_write(ds1307->regmap, RX8130_REG_ALARM_MIN, ald,
663 				sizeof(ald));
664 	if (ret < 0)
665 		return ret;
666 
667 	if (!t->enabled)
668 		return 0;
669 
670 	ctl[2] |= RX8130_REG_CONTROL0_AIE;
671 
672 	return regmap_write(ds1307->regmap, RX8130_REG_CONTROL0, ctl[2]);
673 }
674 
675 static int rx8130_alarm_irq_enable(struct device *dev, unsigned int enabled)
676 {
677 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
678 	int ret, reg;
679 
680 	ret = regmap_read(ds1307->regmap, RX8130_REG_CONTROL0, &reg);
681 	if (ret < 0)
682 		return ret;
683 
684 	if (enabled)
685 		reg |= RX8130_REG_CONTROL0_AIE;
686 	else
687 		reg &= ~RX8130_REG_CONTROL0_AIE;
688 
689 	return regmap_write(ds1307->regmap, RX8130_REG_CONTROL0, reg);
690 }
691 
692 static irqreturn_t mcp794xx_irq(int irq, void *dev_id)
693 {
694 	struct ds1307           *ds1307 = dev_id;
695 	struct mutex            *lock = &ds1307->rtc->ops_lock;
696 	int reg, ret;
697 
698 	mutex_lock(lock);
699 
700 	/* Check and clear alarm 0 interrupt flag. */
701 	ret = regmap_read(ds1307->regmap, MCP794XX_REG_ALARM0_CTRL, &reg);
702 	if (ret)
703 		goto out;
704 	if (!(reg & MCP794XX_BIT_ALMX_IF))
705 		goto out;
706 	reg &= ~MCP794XX_BIT_ALMX_IF;
707 	ret = regmap_write(ds1307->regmap, MCP794XX_REG_ALARM0_CTRL, reg);
708 	if (ret)
709 		goto out;
710 
711 	/* Disable alarm 0. */
712 	ret = regmap_update_bits(ds1307->regmap, MCP794XX_REG_CONTROL,
713 				 MCP794XX_BIT_ALM0_EN, 0);
714 	if (ret)
715 		goto out;
716 
717 	rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
718 
719 out:
720 	mutex_unlock(lock);
721 
722 	return IRQ_HANDLED;
723 }
724 
725 static int mcp794xx_read_alarm(struct device *dev, struct rtc_wkalrm *t)
726 {
727 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
728 	u8 regs[10];
729 	int ret;
730 
731 	/* Read control and alarm 0 registers. */
732 	ret = regmap_bulk_read(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
733 			       sizeof(regs));
734 	if (ret)
735 		return ret;
736 
737 	t->enabled = !!(regs[0] & MCP794XX_BIT_ALM0_EN);
738 
739 	/* Report alarm 0 time assuming 24-hour and day-of-month modes. */
740 	t->time.tm_sec = bcd2bin(regs[3] & 0x7f);
741 	t->time.tm_min = bcd2bin(regs[4] & 0x7f);
742 	t->time.tm_hour = bcd2bin(regs[5] & 0x3f);
743 	t->time.tm_wday = bcd2bin(regs[6] & 0x7) - 1;
744 	t->time.tm_mday = bcd2bin(regs[7] & 0x3f);
745 	t->time.tm_mon = bcd2bin(regs[8] & 0x1f) - 1;
746 	t->time.tm_year = -1;
747 	t->time.tm_yday = -1;
748 	t->time.tm_isdst = -1;
749 
750 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
751 		"enabled=%d polarity=%d irq=%d match=%lu\n", __func__,
752 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
753 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled,
754 		!!(regs[6] & MCP794XX_BIT_ALMX_POL),
755 		!!(regs[6] & MCP794XX_BIT_ALMX_IF),
756 		(regs[6] & MCP794XX_MSK_ALMX_MATCH) >> 4);
757 
758 	return 0;
759 }
760 
761 /*
762  * We may have a random RTC weekday, therefore calculate alarm weekday based
763  * on current weekday we read from the RTC timekeeping regs
764  */
765 static int mcp794xx_alm_weekday(struct device *dev, struct rtc_time *tm_alarm)
766 {
767 	struct rtc_time tm_now;
768 	int days_now, days_alarm, ret;
769 
770 	ret = ds1307_get_time(dev, &tm_now);
771 	if (ret)
772 		return ret;
773 
774 	days_now = div_s64(rtc_tm_to_time64(&tm_now), 24 * 60 * 60);
775 	days_alarm = div_s64(rtc_tm_to_time64(tm_alarm), 24 * 60 * 60);
776 
777 	return (tm_now.tm_wday + days_alarm - days_now) % 7 + 1;
778 }
779 
780 static int mcp794xx_set_alarm(struct device *dev, struct rtc_wkalrm *t)
781 {
782 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
783 	unsigned char regs[10];
784 	int wday, ret;
785 
786 	wday = mcp794xx_alm_weekday(dev, &t->time);
787 	if (wday < 0)
788 		return wday;
789 
790 	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
791 		"enabled=%d pending=%d\n", __func__,
792 		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
793 		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
794 		t->enabled, t->pending);
795 
796 	/* Read control and alarm 0 registers. */
797 	ret = regmap_bulk_read(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
798 			       sizeof(regs));
799 	if (ret)
800 		return ret;
801 
802 	/* Set alarm 0, using 24-hour and day-of-month modes. */
803 	regs[3] = bin2bcd(t->time.tm_sec);
804 	regs[4] = bin2bcd(t->time.tm_min);
805 	regs[5] = bin2bcd(t->time.tm_hour);
806 	regs[6] = wday;
807 	regs[7] = bin2bcd(t->time.tm_mday);
808 	regs[8] = bin2bcd(t->time.tm_mon + 1);
809 
810 	/* Clear the alarm 0 interrupt flag. */
811 	regs[6] &= ~MCP794XX_BIT_ALMX_IF;
812 	/* Set alarm match: second, minute, hour, day, date, month. */
813 	regs[6] |= MCP794XX_MSK_ALMX_MATCH;
814 	/* Disable interrupt. We will not enable until completely programmed */
815 	regs[0] &= ~MCP794XX_BIT_ALM0_EN;
816 
817 	ret = regmap_bulk_write(ds1307->regmap, MCP794XX_REG_CONTROL, regs,
818 				sizeof(regs));
819 	if (ret)
820 		return ret;
821 
822 	if (!t->enabled)
823 		return 0;
824 	regs[0] |= MCP794XX_BIT_ALM0_EN;
825 	return regmap_write(ds1307->regmap, MCP794XX_REG_CONTROL, regs[0]);
826 }
827 
828 static int mcp794xx_alarm_irq_enable(struct device *dev, unsigned int enabled)
829 {
830 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
831 
832 	return regmap_update_bits(ds1307->regmap, MCP794XX_REG_CONTROL,
833 				  MCP794XX_BIT_ALM0_EN,
834 				  enabled ? MCP794XX_BIT_ALM0_EN : 0);
835 }
836 
837 static int m41txx_rtc_read_offset(struct device *dev, long *offset)
838 {
839 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
840 	unsigned int ctrl_reg;
841 	u8 val;
842 
843 	regmap_read(ds1307->regmap, M41TXX_REG_CONTROL, &ctrl_reg);
844 
845 	val = ctrl_reg & M41TXX_M_CALIBRATION;
846 
847 	/* check if positive */
848 	if (ctrl_reg & M41TXX_BIT_CALIB_SIGN)
849 		*offset = (val * M41TXX_POS_OFFSET_STEP_PPB);
850 	else
851 		*offset = -(val * M41TXX_NEG_OFFSET_STEP_PPB);
852 
853 	return 0;
854 }
855 
856 static int m41txx_rtc_set_offset(struct device *dev, long offset)
857 {
858 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
859 	unsigned int ctrl_reg;
860 
861 	if ((offset < M41TXX_MIN_OFFSET) || (offset > M41TXX_MAX_OFFSET))
862 		return -ERANGE;
863 
864 	if (offset >= 0) {
865 		ctrl_reg = DIV_ROUND_CLOSEST(offset,
866 					     M41TXX_POS_OFFSET_STEP_PPB);
867 		ctrl_reg |= M41TXX_BIT_CALIB_SIGN;
868 	} else {
869 		ctrl_reg = DIV_ROUND_CLOSEST(abs(offset),
870 					     M41TXX_NEG_OFFSET_STEP_PPB);
871 	}
872 
873 	return regmap_update_bits(ds1307->regmap, M41TXX_REG_CONTROL,
874 				  M41TXX_M_CALIBRATION | M41TXX_BIT_CALIB_SIGN,
875 				  ctrl_reg);
876 }
877 
878 #ifdef CONFIG_WATCHDOG_CORE
879 static int ds1388_wdt_start(struct watchdog_device *wdt_dev)
880 {
881 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
882 	u8 regs[2];
883 	int ret;
884 
885 	ret = regmap_update_bits(ds1307->regmap, DS1388_REG_FLAG,
886 				 DS1388_BIT_WF, 0);
887 	if (ret)
888 		return ret;
889 
890 	ret = regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
891 				 DS1388_BIT_WDE | DS1388_BIT_RST, 0);
892 	if (ret)
893 		return ret;
894 
895 	/*
896 	 * watchdog timeouts are measured in seconds. So ignore hundredths of
897 	 * seconds field.
898 	 */
899 	regs[0] = 0;
900 	regs[1] = bin2bcd(wdt_dev->timeout);
901 
902 	ret = regmap_bulk_write(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
903 				sizeof(regs));
904 	if (ret)
905 		return ret;
906 
907 	return regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
908 				  DS1388_BIT_WDE | DS1388_BIT_RST,
909 				  DS1388_BIT_WDE | DS1388_BIT_RST);
910 }
911 
912 static int ds1388_wdt_stop(struct watchdog_device *wdt_dev)
913 {
914 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
915 
916 	return regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
917 				  DS1388_BIT_WDE | DS1388_BIT_RST, 0);
918 }
919 
920 static int ds1388_wdt_ping(struct watchdog_device *wdt_dev)
921 {
922 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
923 	u8 regs[2];
924 
925 	return regmap_bulk_read(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
926 				sizeof(regs));
927 }
928 
929 static int ds1388_wdt_set_timeout(struct watchdog_device *wdt_dev,
930 				  unsigned int val)
931 {
932 	struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
933 	u8 regs[2];
934 
935 	wdt_dev->timeout = val;
936 	regs[0] = 0;
937 	regs[1] = bin2bcd(wdt_dev->timeout);
938 
939 	return regmap_bulk_write(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
940 				 sizeof(regs));
941 }
942 #endif
943 
944 static const struct rtc_class_ops rx8130_rtc_ops = {
945 	.read_time      = ds1307_get_time,
946 	.set_time       = ds1307_set_time,
947 	.read_alarm     = rx8130_read_alarm,
948 	.set_alarm      = rx8130_set_alarm,
949 	.alarm_irq_enable = rx8130_alarm_irq_enable,
950 };
951 
952 static const struct rtc_class_ops mcp794xx_rtc_ops = {
953 	.read_time      = ds1307_get_time,
954 	.set_time       = ds1307_set_time,
955 	.read_alarm     = mcp794xx_read_alarm,
956 	.set_alarm      = mcp794xx_set_alarm,
957 	.alarm_irq_enable = mcp794xx_alarm_irq_enable,
958 };
959 
960 static const struct rtc_class_ops m41txx_rtc_ops = {
961 	.read_time      = ds1307_get_time,
962 	.set_time       = ds1307_set_time,
963 	.read_alarm	= ds1337_read_alarm,
964 	.set_alarm	= ds1337_set_alarm,
965 	.alarm_irq_enable = ds1307_alarm_irq_enable,
966 	.read_offset	= m41txx_rtc_read_offset,
967 	.set_offset	= m41txx_rtc_set_offset,
968 };
969 
970 static const struct chip_desc chips[last_ds_type] = {
971 	[ds_1307] = {
972 		.nvram_offset	= 8,
973 		.nvram_size	= 56,
974 	},
975 	[ds_1308] = {
976 		.nvram_offset	= 8,
977 		.nvram_size	= 56,
978 	},
979 	[ds_1337] = {
980 		.alarm		= 1,
981 		.century_reg	= DS1307_REG_MONTH,
982 		.century_bit	= DS1337_BIT_CENTURY,
983 	},
984 	[ds_1338] = {
985 		.nvram_offset	= 8,
986 		.nvram_size	= 56,
987 	},
988 	[ds_1339] = {
989 		.alarm		= 1,
990 		.century_reg	= DS1307_REG_MONTH,
991 		.century_bit	= DS1337_BIT_CENTURY,
992 		.bbsqi_bit	= DS1339_BIT_BBSQI,
993 		.trickle_charger_reg = 0x10,
994 		.do_trickle_setup = &do_trickle_setup_ds1339,
995 		.requires_trickle_resistor = true,
996 		.charge_default = true,
997 	},
998 	[ds_1340] = {
999 		.century_reg	= DS1307_REG_HOUR,
1000 		.century_enable_bit = DS1340_BIT_CENTURY_EN,
1001 		.century_bit	= DS1340_BIT_CENTURY,
1002 		.do_trickle_setup = &do_trickle_setup_ds1339,
1003 		.trickle_charger_reg = 0x08,
1004 		.requires_trickle_resistor = true,
1005 		.charge_default = true,
1006 	},
1007 	[ds_1341] = {
1008 		.century_reg	= DS1307_REG_MONTH,
1009 		.century_bit	= DS1337_BIT_CENTURY,
1010 	},
1011 	[ds_1388] = {
1012 		.offset		= 1,
1013 		.trickle_charger_reg = 0x0a,
1014 	},
1015 	[ds_3231] = {
1016 		.alarm		= 1,
1017 		.century_reg	= DS1307_REG_MONTH,
1018 		.century_bit	= DS1337_BIT_CENTURY,
1019 		.bbsqi_bit	= DS3231_BIT_BBSQW,
1020 	},
1021 	[rx_8130] = {
1022 		.alarm		= 1,
1023 		/* this is battery backed SRAM */
1024 		.nvram_offset	= 0x20,
1025 		.nvram_size	= 4,	/* 32bit (4 word x 8 bit) */
1026 		.offset		= 0x10,
1027 		.irq_handler = rx8130_irq,
1028 		.rtc_ops = &rx8130_rtc_ops,
1029 		.trickle_charger_reg = RX8130_REG_CONTROL1,
1030 		.do_trickle_setup = &do_trickle_setup_rx8130,
1031 	},
1032 	[m41t0] = {
1033 		.rtc_ops	= &m41txx_rtc_ops,
1034 	},
1035 	[m41t00] = {
1036 		.rtc_ops	= &m41txx_rtc_ops,
1037 	},
1038 	[m41t11] = {
1039 		/* this is battery backed SRAM */
1040 		.nvram_offset	= 8,
1041 		.nvram_size	= 56,
1042 		.rtc_ops	= &m41txx_rtc_ops,
1043 	},
1044 	[mcp794xx] = {
1045 		.alarm		= 1,
1046 		/* this is battery backed SRAM */
1047 		.nvram_offset	= 0x20,
1048 		.nvram_size	= 0x40,
1049 		.irq_handler = mcp794xx_irq,
1050 		.rtc_ops = &mcp794xx_rtc_ops,
1051 	},
1052 };
1053 
1054 static const struct i2c_device_id ds1307_id[] = {
1055 	{ "ds1307", ds_1307 },
1056 	{ "ds1308", ds_1308 },
1057 	{ "ds1337", ds_1337 },
1058 	{ "ds1338", ds_1338 },
1059 	{ "ds1339", ds_1339 },
1060 	{ "ds1388", ds_1388 },
1061 	{ "ds1340", ds_1340 },
1062 	{ "ds1341", ds_1341 },
1063 	{ "ds3231", ds_3231 },
1064 	{ "m41t0", m41t0 },
1065 	{ "m41t00", m41t00 },
1066 	{ "m41t11", m41t11 },
1067 	{ "mcp7940x", mcp794xx },
1068 	{ "mcp7941x", mcp794xx },
1069 	{ "pt7c4338", ds_1307 },
1070 	{ "rx8025", rx_8025 },
1071 	{ "isl12057", ds_1337 },
1072 	{ "rx8130", rx_8130 },
1073 	{ }
1074 };
1075 MODULE_DEVICE_TABLE(i2c, ds1307_id);
1076 
1077 static const struct of_device_id ds1307_of_match[] = {
1078 	{
1079 		.compatible = "dallas,ds1307",
1080 		.data = (void *)ds_1307
1081 	},
1082 	{
1083 		.compatible = "dallas,ds1308",
1084 		.data = (void *)ds_1308
1085 	},
1086 	{
1087 		.compatible = "dallas,ds1337",
1088 		.data = (void *)ds_1337
1089 	},
1090 	{
1091 		.compatible = "dallas,ds1338",
1092 		.data = (void *)ds_1338
1093 	},
1094 	{
1095 		.compatible = "dallas,ds1339",
1096 		.data = (void *)ds_1339
1097 	},
1098 	{
1099 		.compatible = "dallas,ds1388",
1100 		.data = (void *)ds_1388
1101 	},
1102 	{
1103 		.compatible = "dallas,ds1340",
1104 		.data = (void *)ds_1340
1105 	},
1106 	{
1107 		.compatible = "dallas,ds1341",
1108 		.data = (void *)ds_1341
1109 	},
1110 	{
1111 		.compatible = "maxim,ds3231",
1112 		.data = (void *)ds_3231
1113 	},
1114 	{
1115 		.compatible = "st,m41t0",
1116 		.data = (void *)m41t0
1117 	},
1118 	{
1119 		.compatible = "st,m41t00",
1120 		.data = (void *)m41t00
1121 	},
1122 	{
1123 		.compatible = "st,m41t11",
1124 		.data = (void *)m41t11
1125 	},
1126 	{
1127 		.compatible = "microchip,mcp7940x",
1128 		.data = (void *)mcp794xx
1129 	},
1130 	{
1131 		.compatible = "microchip,mcp7941x",
1132 		.data = (void *)mcp794xx
1133 	},
1134 	{
1135 		.compatible = "pericom,pt7c4338",
1136 		.data = (void *)ds_1307
1137 	},
1138 	{
1139 		.compatible = "epson,rx8025",
1140 		.data = (void *)rx_8025
1141 	},
1142 	{
1143 		.compatible = "isil,isl12057",
1144 		.data = (void *)ds_1337
1145 	},
1146 	{
1147 		.compatible = "epson,rx8130",
1148 		.data = (void *)rx_8130
1149 	},
1150 	{ }
1151 };
1152 MODULE_DEVICE_TABLE(of, ds1307_of_match);
1153 
1154 /*
1155  * The ds1337 and ds1339 both have two alarms, but we only use the first
1156  * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
1157  * signal; ds1339 chips have only one alarm signal.
1158  */
1159 static irqreturn_t ds1307_irq(int irq, void *dev_id)
1160 {
1161 	struct ds1307		*ds1307 = dev_id;
1162 	struct mutex		*lock = &ds1307->rtc->ops_lock;
1163 	int			stat, ret;
1164 
1165 	mutex_lock(lock);
1166 	ret = regmap_read(ds1307->regmap, DS1337_REG_STATUS, &stat);
1167 	if (ret)
1168 		goto out;
1169 
1170 	if (stat & DS1337_BIT_A1I) {
1171 		stat &= ~DS1337_BIT_A1I;
1172 		regmap_write(ds1307->regmap, DS1337_REG_STATUS, stat);
1173 
1174 		ret = regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
1175 					 DS1337_BIT_A1IE, 0);
1176 		if (ret)
1177 			goto out;
1178 
1179 		rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
1180 	}
1181 
1182 out:
1183 	mutex_unlock(lock);
1184 
1185 	return IRQ_HANDLED;
1186 }
1187 
1188 /*----------------------------------------------------------------------*/
1189 
1190 static const struct rtc_class_ops ds13xx_rtc_ops = {
1191 	.read_time	= ds1307_get_time,
1192 	.set_time	= ds1307_set_time,
1193 	.read_alarm	= ds1337_read_alarm,
1194 	.set_alarm	= ds1337_set_alarm,
1195 	.alarm_irq_enable = ds1307_alarm_irq_enable,
1196 };
1197 
1198 static ssize_t frequency_test_store(struct device *dev,
1199 				    struct device_attribute *attr,
1200 				    const char *buf, size_t count)
1201 {
1202 	struct ds1307 *ds1307 = dev_get_drvdata(dev->parent);
1203 	bool freq_test_en;
1204 	int ret;
1205 
1206 	ret = kstrtobool(buf, &freq_test_en);
1207 	if (ret) {
1208 		dev_err(dev, "Failed to store RTC Frequency Test attribute\n");
1209 		return ret;
1210 	}
1211 
1212 	regmap_update_bits(ds1307->regmap, M41TXX_REG_CONTROL, M41TXX_BIT_FT,
1213 			   freq_test_en ? M41TXX_BIT_FT : 0);
1214 
1215 	return count;
1216 }
1217 
1218 static ssize_t frequency_test_show(struct device *dev,
1219 				   struct device_attribute *attr,
1220 				   char *buf)
1221 {
1222 	struct ds1307 *ds1307 = dev_get_drvdata(dev->parent);
1223 	unsigned int ctrl_reg;
1224 
1225 	regmap_read(ds1307->regmap, M41TXX_REG_CONTROL, &ctrl_reg);
1226 
1227 	return sysfs_emit(buf, (ctrl_reg & M41TXX_BIT_FT) ? "on\n" : "off\n");
1228 }
1229 
1230 static DEVICE_ATTR_RW(frequency_test);
1231 
1232 static struct attribute *rtc_freq_test_attrs[] = {
1233 	&dev_attr_frequency_test.attr,
1234 	NULL,
1235 };
1236 
1237 static const struct attribute_group rtc_freq_test_attr_group = {
1238 	.attrs		= rtc_freq_test_attrs,
1239 };
1240 
1241 static int ds1307_add_frequency_test(struct ds1307 *ds1307)
1242 {
1243 	int err;
1244 
1245 	switch (ds1307->type) {
1246 	case m41t0:
1247 	case m41t00:
1248 	case m41t11:
1249 		err = rtc_add_group(ds1307->rtc, &rtc_freq_test_attr_group);
1250 		if (err)
1251 			return err;
1252 		break;
1253 	default:
1254 		break;
1255 	}
1256 
1257 	return 0;
1258 }
1259 
1260 /*----------------------------------------------------------------------*/
1261 
1262 static int ds1307_nvram_read(void *priv, unsigned int offset, void *val,
1263 			     size_t bytes)
1264 {
1265 	struct ds1307 *ds1307 = priv;
1266 	const struct chip_desc *chip = &chips[ds1307->type];
1267 
1268 	return regmap_bulk_read(ds1307->regmap, chip->nvram_offset + offset,
1269 				val, bytes);
1270 }
1271 
1272 static int ds1307_nvram_write(void *priv, unsigned int offset, void *val,
1273 			      size_t bytes)
1274 {
1275 	struct ds1307 *ds1307 = priv;
1276 	const struct chip_desc *chip = &chips[ds1307->type];
1277 
1278 	return regmap_bulk_write(ds1307->regmap, chip->nvram_offset + offset,
1279 				 val, bytes);
1280 }
1281 
1282 /*----------------------------------------------------------------------*/
1283 
1284 static u8 ds1307_trickle_init(struct ds1307 *ds1307,
1285 			      const struct chip_desc *chip)
1286 {
1287 	u32 ohms, chargeable;
1288 	bool diode = chip->charge_default;
1289 
1290 	if (!chip->do_trickle_setup)
1291 		return 0;
1292 
1293 	if (device_property_read_u32(ds1307->dev, "trickle-resistor-ohms",
1294 				     &ohms) && chip->requires_trickle_resistor)
1295 		return 0;
1296 
1297 	/* aux-voltage-chargeable takes precedence over the deprecated
1298 	 * trickle-diode-disable
1299 	 */
1300 	if (!device_property_read_u32(ds1307->dev, "aux-voltage-chargeable",
1301 				     &chargeable)) {
1302 		switch (chargeable) {
1303 		case 0:
1304 			diode = false;
1305 			break;
1306 		case 1:
1307 			diode = true;
1308 			break;
1309 		default:
1310 			dev_warn(ds1307->dev,
1311 				 "unsupported aux-voltage-chargeable value\n");
1312 			break;
1313 		}
1314 	} else if (device_property_read_bool(ds1307->dev,
1315 					     "trickle-diode-disable")) {
1316 		diode = false;
1317 	}
1318 
1319 	return chip->do_trickle_setup(ds1307, ohms, diode);
1320 }
1321 
1322 /*----------------------------------------------------------------------*/
1323 
1324 #if IS_REACHABLE(CONFIG_HWMON)
1325 
1326 /*
1327  * Temperature sensor support for ds3231 devices.
1328  */
1329 
1330 #define DS3231_REG_TEMPERATURE	0x11
1331 
1332 /*
1333  * A user-initiated temperature conversion is not started by this function,
1334  * so the temperature is updated once every 64 seconds.
1335  */
1336 static int ds3231_hwmon_read_temp(struct device *dev, s32 *mC)
1337 {
1338 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
1339 	u8 temp_buf[2];
1340 	s16 temp;
1341 	int ret;
1342 
1343 	ret = regmap_bulk_read(ds1307->regmap, DS3231_REG_TEMPERATURE,
1344 			       temp_buf, sizeof(temp_buf));
1345 	if (ret)
1346 		return ret;
1347 	/*
1348 	 * Temperature is represented as a 10-bit code with a resolution of
1349 	 * 0.25 degree celsius and encoded in two's complement format.
1350 	 */
1351 	temp = (temp_buf[0] << 8) | temp_buf[1];
1352 	temp >>= 6;
1353 	*mC = temp * 250;
1354 
1355 	return 0;
1356 }
1357 
1358 static ssize_t ds3231_hwmon_show_temp(struct device *dev,
1359 				      struct device_attribute *attr, char *buf)
1360 {
1361 	int ret;
1362 	s32 temp;
1363 
1364 	ret = ds3231_hwmon_read_temp(dev, &temp);
1365 	if (ret)
1366 		return ret;
1367 
1368 	return sprintf(buf, "%d\n", temp);
1369 }
1370 static SENSOR_DEVICE_ATTR(temp1_input, 0444, ds3231_hwmon_show_temp,
1371 			  NULL, 0);
1372 
1373 static struct attribute *ds3231_hwmon_attrs[] = {
1374 	&sensor_dev_attr_temp1_input.dev_attr.attr,
1375 	NULL,
1376 };
1377 ATTRIBUTE_GROUPS(ds3231_hwmon);
1378 
1379 static void ds1307_hwmon_register(struct ds1307 *ds1307)
1380 {
1381 	struct device *dev;
1382 
1383 	if (ds1307->type != ds_3231)
1384 		return;
1385 
1386 	dev = devm_hwmon_device_register_with_groups(ds1307->dev, ds1307->name,
1387 						     ds1307,
1388 						     ds3231_hwmon_groups);
1389 	if (IS_ERR(dev)) {
1390 		dev_warn(ds1307->dev, "unable to register hwmon device %ld\n",
1391 			 PTR_ERR(dev));
1392 	}
1393 }
1394 
1395 #else
1396 
1397 static void ds1307_hwmon_register(struct ds1307 *ds1307)
1398 {
1399 }
1400 
1401 #endif /* CONFIG_RTC_DRV_DS1307_HWMON */
1402 
1403 /*----------------------------------------------------------------------*/
1404 
1405 /*
1406  * Square-wave output support for DS3231
1407  * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS3231.pdf
1408  */
1409 #ifdef CONFIG_COMMON_CLK
1410 
1411 enum {
1412 	DS3231_CLK_SQW = 0,
1413 	DS3231_CLK_32KHZ,
1414 };
1415 
1416 #define clk_sqw_to_ds1307(clk)	\
1417 	container_of(clk, struct ds1307, clks[DS3231_CLK_SQW])
1418 #define clk_32khz_to_ds1307(clk)	\
1419 	container_of(clk, struct ds1307, clks[DS3231_CLK_32KHZ])
1420 
1421 static int ds3231_clk_sqw_rates[] = {
1422 	1,
1423 	1024,
1424 	4096,
1425 	8192,
1426 };
1427 
1428 static int ds1337_write_control(struct ds1307 *ds1307, u8 mask, u8 value)
1429 {
1430 	struct mutex *lock = &ds1307->rtc->ops_lock;
1431 	int ret;
1432 
1433 	mutex_lock(lock);
1434 	ret = regmap_update_bits(ds1307->regmap, DS1337_REG_CONTROL,
1435 				 mask, value);
1436 	mutex_unlock(lock);
1437 
1438 	return ret;
1439 }
1440 
1441 static unsigned long ds3231_clk_sqw_recalc_rate(struct clk_hw *hw,
1442 						unsigned long parent_rate)
1443 {
1444 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1445 	int control, ret;
1446 	int rate_sel = 0;
1447 
1448 	ret = regmap_read(ds1307->regmap, DS1337_REG_CONTROL, &control);
1449 	if (ret)
1450 		return ret;
1451 	if (control & DS1337_BIT_RS1)
1452 		rate_sel += 1;
1453 	if (control & DS1337_BIT_RS2)
1454 		rate_sel += 2;
1455 
1456 	return ds3231_clk_sqw_rates[rate_sel];
1457 }
1458 
1459 static long ds3231_clk_sqw_round_rate(struct clk_hw *hw, unsigned long rate,
1460 				      unsigned long *prate)
1461 {
1462 	int i;
1463 
1464 	for (i = ARRAY_SIZE(ds3231_clk_sqw_rates) - 1; i >= 0; i--) {
1465 		if (ds3231_clk_sqw_rates[i] <= rate)
1466 			return ds3231_clk_sqw_rates[i];
1467 	}
1468 
1469 	return 0;
1470 }
1471 
1472 static int ds3231_clk_sqw_set_rate(struct clk_hw *hw, unsigned long rate,
1473 				   unsigned long parent_rate)
1474 {
1475 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1476 	int control = 0;
1477 	int rate_sel;
1478 
1479 	for (rate_sel = 0; rate_sel < ARRAY_SIZE(ds3231_clk_sqw_rates);
1480 			rate_sel++) {
1481 		if (ds3231_clk_sqw_rates[rate_sel] == rate)
1482 			break;
1483 	}
1484 
1485 	if (rate_sel == ARRAY_SIZE(ds3231_clk_sqw_rates))
1486 		return -EINVAL;
1487 
1488 	if (rate_sel & 1)
1489 		control |= DS1337_BIT_RS1;
1490 	if (rate_sel & 2)
1491 		control |= DS1337_BIT_RS2;
1492 
1493 	return ds1337_write_control(ds1307, DS1337_BIT_RS1 | DS1337_BIT_RS2,
1494 				control);
1495 }
1496 
1497 static int ds3231_clk_sqw_prepare(struct clk_hw *hw)
1498 {
1499 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1500 
1501 	return ds1337_write_control(ds1307, DS1337_BIT_INTCN, 0);
1502 }
1503 
1504 static void ds3231_clk_sqw_unprepare(struct clk_hw *hw)
1505 {
1506 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1507 
1508 	ds1337_write_control(ds1307, DS1337_BIT_INTCN, DS1337_BIT_INTCN);
1509 }
1510 
1511 static int ds3231_clk_sqw_is_prepared(struct clk_hw *hw)
1512 {
1513 	struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
1514 	int control, ret;
1515 
1516 	ret = regmap_read(ds1307->regmap, DS1337_REG_CONTROL, &control);
1517 	if (ret)
1518 		return ret;
1519 
1520 	return !(control & DS1337_BIT_INTCN);
1521 }
1522 
1523 static const struct clk_ops ds3231_clk_sqw_ops = {
1524 	.prepare = ds3231_clk_sqw_prepare,
1525 	.unprepare = ds3231_clk_sqw_unprepare,
1526 	.is_prepared = ds3231_clk_sqw_is_prepared,
1527 	.recalc_rate = ds3231_clk_sqw_recalc_rate,
1528 	.round_rate = ds3231_clk_sqw_round_rate,
1529 	.set_rate = ds3231_clk_sqw_set_rate,
1530 };
1531 
1532 static unsigned long ds3231_clk_32khz_recalc_rate(struct clk_hw *hw,
1533 						  unsigned long parent_rate)
1534 {
1535 	return 32768;
1536 }
1537 
1538 static int ds3231_clk_32khz_control(struct ds1307 *ds1307, bool enable)
1539 {
1540 	struct mutex *lock = &ds1307->rtc->ops_lock;
1541 	int ret;
1542 
1543 	mutex_lock(lock);
1544 	ret = regmap_update_bits(ds1307->regmap, DS1337_REG_STATUS,
1545 				 DS3231_BIT_EN32KHZ,
1546 				 enable ? DS3231_BIT_EN32KHZ : 0);
1547 	mutex_unlock(lock);
1548 
1549 	return ret;
1550 }
1551 
1552 static int ds3231_clk_32khz_prepare(struct clk_hw *hw)
1553 {
1554 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1555 
1556 	return ds3231_clk_32khz_control(ds1307, true);
1557 }
1558 
1559 static void ds3231_clk_32khz_unprepare(struct clk_hw *hw)
1560 {
1561 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1562 
1563 	ds3231_clk_32khz_control(ds1307, false);
1564 }
1565 
1566 static int ds3231_clk_32khz_is_prepared(struct clk_hw *hw)
1567 {
1568 	struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
1569 	int status, ret;
1570 
1571 	ret = regmap_read(ds1307->regmap, DS1337_REG_STATUS, &status);
1572 	if (ret)
1573 		return ret;
1574 
1575 	return !!(status & DS3231_BIT_EN32KHZ);
1576 }
1577 
1578 static const struct clk_ops ds3231_clk_32khz_ops = {
1579 	.prepare = ds3231_clk_32khz_prepare,
1580 	.unprepare = ds3231_clk_32khz_unprepare,
1581 	.is_prepared = ds3231_clk_32khz_is_prepared,
1582 	.recalc_rate = ds3231_clk_32khz_recalc_rate,
1583 };
1584 
1585 static const char *ds3231_clks_names[] = {
1586 	[DS3231_CLK_SQW] = "ds3231_clk_sqw",
1587 	[DS3231_CLK_32KHZ] = "ds3231_clk_32khz",
1588 };
1589 
1590 static struct clk_init_data ds3231_clks_init[] = {
1591 	[DS3231_CLK_SQW] = {
1592 		.ops = &ds3231_clk_sqw_ops,
1593 	},
1594 	[DS3231_CLK_32KHZ] = {
1595 		.ops = &ds3231_clk_32khz_ops,
1596 	},
1597 };
1598 
1599 static int ds3231_clks_register(struct ds1307 *ds1307)
1600 {
1601 	struct device_node *node = ds1307->dev->of_node;
1602 	struct clk_onecell_data	*onecell;
1603 	int i;
1604 
1605 	onecell = devm_kzalloc(ds1307->dev, sizeof(*onecell), GFP_KERNEL);
1606 	if (!onecell)
1607 		return -ENOMEM;
1608 
1609 	onecell->clk_num = ARRAY_SIZE(ds3231_clks_init);
1610 	onecell->clks = devm_kcalloc(ds1307->dev, onecell->clk_num,
1611 				     sizeof(onecell->clks[0]), GFP_KERNEL);
1612 	if (!onecell->clks)
1613 		return -ENOMEM;
1614 
1615 	/* optional override of the clockname */
1616 	device_property_read_string_array(ds1307->dev, "clock-output-names",
1617 					  ds3231_clks_names,
1618 					  ARRAY_SIZE(ds3231_clks_names));
1619 
1620 	for (i = 0; i < ARRAY_SIZE(ds3231_clks_init); i++) {
1621 		struct clk_init_data init = ds3231_clks_init[i];
1622 
1623 		/*
1624 		 * Interrupt signal due to alarm conditions and square-wave
1625 		 * output share same pin, so don't initialize both.
1626 		 */
1627 		if (i == DS3231_CLK_SQW && test_bit(RTC_FEATURE_ALARM, ds1307->rtc->features))
1628 			continue;
1629 
1630 		init.name = ds3231_clks_names[i];
1631 		ds1307->clks[i].init = &init;
1632 
1633 		onecell->clks[i] = devm_clk_register(ds1307->dev,
1634 						     &ds1307->clks[i]);
1635 		if (IS_ERR(onecell->clks[i]))
1636 			return PTR_ERR(onecell->clks[i]);
1637 	}
1638 
1639 	if (node)
1640 		of_clk_add_provider(node, of_clk_src_onecell_get, onecell);
1641 
1642 	return 0;
1643 }
1644 
1645 static void ds1307_clks_register(struct ds1307 *ds1307)
1646 {
1647 	int ret;
1648 
1649 	if (ds1307->type != ds_3231)
1650 		return;
1651 
1652 	ret = ds3231_clks_register(ds1307);
1653 	if (ret) {
1654 		dev_warn(ds1307->dev, "unable to register clock device %d\n",
1655 			 ret);
1656 	}
1657 }
1658 
1659 #else
1660 
1661 static void ds1307_clks_register(struct ds1307 *ds1307)
1662 {
1663 }
1664 
1665 #endif /* CONFIG_COMMON_CLK */
1666 
1667 #ifdef CONFIG_WATCHDOG_CORE
1668 static const struct watchdog_info ds1388_wdt_info = {
1669 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
1670 	.identity = "DS1388 watchdog",
1671 };
1672 
1673 static const struct watchdog_ops ds1388_wdt_ops = {
1674 	.owner = THIS_MODULE,
1675 	.start = ds1388_wdt_start,
1676 	.stop = ds1388_wdt_stop,
1677 	.ping = ds1388_wdt_ping,
1678 	.set_timeout = ds1388_wdt_set_timeout,
1679 
1680 };
1681 
1682 static void ds1307_wdt_register(struct ds1307 *ds1307)
1683 {
1684 	struct watchdog_device	*wdt;
1685 	int err;
1686 	int val;
1687 
1688 	if (ds1307->type != ds_1388)
1689 		return;
1690 
1691 	wdt = devm_kzalloc(ds1307->dev, sizeof(*wdt), GFP_KERNEL);
1692 	if (!wdt)
1693 		return;
1694 
1695 	err = regmap_read(ds1307->regmap, DS1388_REG_FLAG, &val);
1696 	if (!err && val & DS1388_BIT_WF)
1697 		wdt->bootstatus = WDIOF_CARDRESET;
1698 
1699 	wdt->info = &ds1388_wdt_info;
1700 	wdt->ops = &ds1388_wdt_ops;
1701 	wdt->timeout = 99;
1702 	wdt->max_timeout = 99;
1703 	wdt->min_timeout = 1;
1704 
1705 	watchdog_init_timeout(wdt, 0, ds1307->dev);
1706 	watchdog_set_drvdata(wdt, ds1307);
1707 	devm_watchdog_register_device(ds1307->dev, wdt);
1708 }
1709 #else
1710 static void ds1307_wdt_register(struct ds1307 *ds1307)
1711 {
1712 }
1713 #endif /* CONFIG_WATCHDOG_CORE */
1714 
1715 static const struct regmap_config regmap_config = {
1716 	.reg_bits = 8,
1717 	.val_bits = 8,
1718 };
1719 
1720 static int ds1307_probe(struct i2c_client *client)
1721 {
1722 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
1723 	struct ds1307		*ds1307;
1724 	const void		*match;
1725 	int			err = -ENODEV;
1726 	int			tmp;
1727 	const struct chip_desc	*chip;
1728 	bool			want_irq;
1729 	bool			ds1307_can_wakeup_device = false;
1730 	unsigned char		regs[8];
1731 	struct ds1307_platform_data *pdata = dev_get_platdata(&client->dev);
1732 	u8			trickle_charger_setup = 0;
1733 
1734 	ds1307 = devm_kzalloc(&client->dev, sizeof(struct ds1307), GFP_KERNEL);
1735 	if (!ds1307)
1736 		return -ENOMEM;
1737 
1738 	dev_set_drvdata(&client->dev, ds1307);
1739 	ds1307->dev = &client->dev;
1740 	ds1307->name = client->name;
1741 
1742 	ds1307->regmap = devm_regmap_init_i2c(client, &regmap_config);
1743 	if (IS_ERR(ds1307->regmap)) {
1744 		dev_err(ds1307->dev, "regmap allocation failed\n");
1745 		return PTR_ERR(ds1307->regmap);
1746 	}
1747 
1748 	i2c_set_clientdata(client, ds1307);
1749 
1750 	match = device_get_match_data(&client->dev);
1751 	if (match) {
1752 		ds1307->type = (uintptr_t)match;
1753 		chip = &chips[ds1307->type];
1754 	} else if (id) {
1755 		chip = &chips[id->driver_data];
1756 		ds1307->type = id->driver_data;
1757 	} else {
1758 		return -ENODEV;
1759 	}
1760 
1761 	want_irq = client->irq > 0 && chip->alarm;
1762 
1763 	if (!pdata)
1764 		trickle_charger_setup = ds1307_trickle_init(ds1307, chip);
1765 	else if (pdata->trickle_charger_setup)
1766 		trickle_charger_setup = pdata->trickle_charger_setup;
1767 
1768 	if (trickle_charger_setup && chip->trickle_charger_reg) {
1769 		dev_dbg(ds1307->dev,
1770 			"writing trickle charger info 0x%x to 0x%x\n",
1771 			trickle_charger_setup, chip->trickle_charger_reg);
1772 		regmap_write(ds1307->regmap, chip->trickle_charger_reg,
1773 			     trickle_charger_setup);
1774 	}
1775 
1776 /*
1777  * For devices with no IRQ directly connected to the SoC, the RTC chip
1778  * can be forced as a wakeup source by stating that explicitly in
1779  * the device's .dts file using the "wakeup-source" boolean property.
1780  * If the "wakeup-source" property is set, don't request an IRQ.
1781  * This will guarantee the 'wakealarm' sysfs entry is available on the device,
1782  * if supported by the RTC.
1783  */
1784 	if (chip->alarm && device_property_read_bool(&client->dev, "wakeup-source"))
1785 		ds1307_can_wakeup_device = true;
1786 
1787 	switch (ds1307->type) {
1788 	case ds_1337:
1789 	case ds_1339:
1790 	case ds_1341:
1791 	case ds_3231:
1792 		/* get registers that the "rtc" read below won't read... */
1793 		err = regmap_bulk_read(ds1307->regmap, DS1337_REG_CONTROL,
1794 				       regs, 2);
1795 		if (err) {
1796 			dev_dbg(ds1307->dev, "read error %d\n", err);
1797 			goto exit;
1798 		}
1799 
1800 		/* oscillator off?  turn it on, so clock can tick. */
1801 		if (regs[0] & DS1337_BIT_nEOSC)
1802 			regs[0] &= ~DS1337_BIT_nEOSC;
1803 
1804 		/*
1805 		 * Using IRQ or defined as wakeup-source?
1806 		 * Disable the square wave and both alarms.
1807 		 * For some variants, be sure alarms can trigger when we're
1808 		 * running on Vbackup (BBSQI/BBSQW)
1809 		 */
1810 		if (want_irq || ds1307_can_wakeup_device) {
1811 			regs[0] |= DS1337_BIT_INTCN | chip->bbsqi_bit;
1812 			regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
1813 		}
1814 
1815 		regmap_write(ds1307->regmap, DS1337_REG_CONTROL,
1816 			     regs[0]);
1817 
1818 		/* oscillator fault?  clear flag, and warn */
1819 		if (regs[1] & DS1337_BIT_OSF) {
1820 			regmap_write(ds1307->regmap, DS1337_REG_STATUS,
1821 				     regs[1] & ~DS1337_BIT_OSF);
1822 			dev_warn(ds1307->dev, "SET TIME!\n");
1823 		}
1824 		break;
1825 
1826 	case rx_8025:
1827 		err = regmap_bulk_read(ds1307->regmap,
1828 				       RX8025_REG_CTRL1 << 4 | 0x08, regs, 2);
1829 		if (err) {
1830 			dev_dbg(ds1307->dev, "read error %d\n", err);
1831 			goto exit;
1832 		}
1833 
1834 		/* oscillator off?  turn it on, so clock can tick. */
1835 		if (!(regs[1] & RX8025_BIT_XST)) {
1836 			regs[1] |= RX8025_BIT_XST;
1837 			regmap_write(ds1307->regmap,
1838 				     RX8025_REG_CTRL2 << 4 | 0x08,
1839 				     regs[1]);
1840 			dev_warn(ds1307->dev,
1841 				 "oscillator stop detected - SET TIME!\n");
1842 		}
1843 
1844 		if (regs[1] & RX8025_BIT_PON) {
1845 			regs[1] &= ~RX8025_BIT_PON;
1846 			regmap_write(ds1307->regmap,
1847 				     RX8025_REG_CTRL2 << 4 | 0x08,
1848 				     regs[1]);
1849 			dev_warn(ds1307->dev, "power-on detected\n");
1850 		}
1851 
1852 		if (regs[1] & RX8025_BIT_VDET) {
1853 			regs[1] &= ~RX8025_BIT_VDET;
1854 			regmap_write(ds1307->regmap,
1855 				     RX8025_REG_CTRL2 << 4 | 0x08,
1856 				     regs[1]);
1857 			dev_warn(ds1307->dev, "voltage drop detected\n");
1858 		}
1859 
1860 		/* make sure we are running in 24hour mode */
1861 		if (!(regs[0] & RX8025_BIT_2412)) {
1862 			u8 hour;
1863 
1864 			/* switch to 24 hour mode */
1865 			regmap_write(ds1307->regmap,
1866 				     RX8025_REG_CTRL1 << 4 | 0x08,
1867 				     regs[0] | RX8025_BIT_2412);
1868 
1869 			err = regmap_bulk_read(ds1307->regmap,
1870 					       RX8025_REG_CTRL1 << 4 | 0x08,
1871 					       regs, 2);
1872 			if (err) {
1873 				dev_dbg(ds1307->dev, "read error %d\n", err);
1874 				goto exit;
1875 			}
1876 
1877 			/* correct hour */
1878 			hour = bcd2bin(regs[DS1307_REG_HOUR]);
1879 			if (hour == 12)
1880 				hour = 0;
1881 			if (regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1882 				hour += 12;
1883 
1884 			regmap_write(ds1307->regmap,
1885 				     DS1307_REG_HOUR << 4 | 0x08, hour);
1886 		}
1887 		break;
1888 	case ds_1388:
1889 		err = regmap_read(ds1307->regmap, DS1388_REG_CONTROL, &tmp);
1890 		if (err) {
1891 			dev_dbg(ds1307->dev, "read error %d\n", err);
1892 			goto exit;
1893 		}
1894 
1895 		/* oscillator off?  turn it on, so clock can tick. */
1896 		if (tmp & DS1388_BIT_nEOSC) {
1897 			tmp &= ~DS1388_BIT_nEOSC;
1898 			regmap_write(ds1307->regmap, DS1388_REG_CONTROL, tmp);
1899 		}
1900 		break;
1901 	default:
1902 		break;
1903 	}
1904 
1905 	/* read RTC registers */
1906 	err = regmap_bulk_read(ds1307->regmap, chip->offset, regs,
1907 			       sizeof(regs));
1908 	if (err) {
1909 		dev_dbg(ds1307->dev, "read error %d\n", err);
1910 		goto exit;
1911 	}
1912 
1913 	if (ds1307->type == mcp794xx &&
1914 	    !(regs[DS1307_REG_WDAY] & MCP794XX_BIT_VBATEN)) {
1915 		regmap_write(ds1307->regmap, DS1307_REG_WDAY,
1916 			     regs[DS1307_REG_WDAY] |
1917 			     MCP794XX_BIT_VBATEN);
1918 	}
1919 
1920 	tmp = regs[DS1307_REG_HOUR];
1921 	switch (ds1307->type) {
1922 	case ds_1340:
1923 	case m41t0:
1924 	case m41t00:
1925 	case m41t11:
1926 		/*
1927 		 * NOTE: ignores century bits; fix before deploying
1928 		 * systems that will run through year 2100.
1929 		 */
1930 		break;
1931 	case rx_8025:
1932 		break;
1933 	default:
1934 		if (!(tmp & DS1307_BIT_12HR))
1935 			break;
1936 
1937 		/*
1938 		 * Be sure we're in 24 hour mode.  Multi-master systems
1939 		 * take note...
1940 		 */
1941 		tmp = bcd2bin(tmp & 0x1f);
1942 		if (tmp == 12)
1943 			tmp = 0;
1944 		if (regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1945 			tmp += 12;
1946 		regmap_write(ds1307->regmap, chip->offset + DS1307_REG_HOUR,
1947 			     bin2bcd(tmp));
1948 	}
1949 
1950 	ds1307->rtc = devm_rtc_allocate_device(ds1307->dev);
1951 	if (IS_ERR(ds1307->rtc))
1952 		return PTR_ERR(ds1307->rtc);
1953 
1954 	if (want_irq || ds1307_can_wakeup_device)
1955 		device_set_wakeup_capable(ds1307->dev, true);
1956 	else
1957 		clear_bit(RTC_FEATURE_ALARM, ds1307->rtc->features);
1958 
1959 	if (ds1307_can_wakeup_device && !want_irq) {
1960 		dev_info(ds1307->dev,
1961 			 "'wakeup-source' is set, request for an IRQ is disabled!\n");
1962 		/* We cannot support UIE mode if we do not have an IRQ line */
1963 		clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, ds1307->rtc->features);
1964 	}
1965 
1966 	if (want_irq) {
1967 		err = devm_request_threaded_irq(ds1307->dev, client->irq, NULL,
1968 						chip->irq_handler ?: ds1307_irq,
1969 						IRQF_SHARED | IRQF_ONESHOT,
1970 						ds1307->name, ds1307);
1971 		if (err) {
1972 			client->irq = 0;
1973 			device_set_wakeup_capable(ds1307->dev, false);
1974 			clear_bit(RTC_FEATURE_ALARM, ds1307->rtc->features);
1975 			dev_err(ds1307->dev, "unable to request IRQ!\n");
1976 		} else {
1977 			dev_dbg(ds1307->dev, "got IRQ %d\n", client->irq);
1978 		}
1979 	}
1980 
1981 	ds1307->rtc->ops = chip->rtc_ops ?: &ds13xx_rtc_ops;
1982 	err = ds1307_add_frequency_test(ds1307);
1983 	if (err)
1984 		return err;
1985 
1986 	err = devm_rtc_register_device(ds1307->rtc);
1987 	if (err)
1988 		return err;
1989 
1990 	if (chip->nvram_size) {
1991 		struct nvmem_config nvmem_cfg = {
1992 			.name = "ds1307_nvram",
1993 			.word_size = 1,
1994 			.stride = 1,
1995 			.size = chip->nvram_size,
1996 			.reg_read = ds1307_nvram_read,
1997 			.reg_write = ds1307_nvram_write,
1998 			.priv = ds1307,
1999 		};
2000 
2001 		devm_rtc_nvmem_register(ds1307->rtc, &nvmem_cfg);
2002 	}
2003 
2004 	ds1307_hwmon_register(ds1307);
2005 	ds1307_clks_register(ds1307);
2006 	ds1307_wdt_register(ds1307);
2007 
2008 	return 0;
2009 
2010 exit:
2011 	return err;
2012 }
2013 
2014 static struct i2c_driver ds1307_driver = {
2015 	.driver = {
2016 		.name	= "rtc-ds1307",
2017 		.of_match_table = ds1307_of_match,
2018 	},
2019 	.probe		= ds1307_probe,
2020 	.id_table	= ds1307_id,
2021 };
2022 
2023 module_i2c_driver(ds1307_driver);
2024 
2025 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
2026 MODULE_LICENSE("GPL");
2027