xref: /openbmc/linux/drivers/rtc/rtc-rs5c372.c (revision 6f4eaea2)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * An I2C driver for Ricoh RS5C372, R2025S/D and RV5C38[67] RTCs
4  *
5  * Copyright (C) 2005 Pavel Mironchik <pmironchik@optifacio.net>
6  * Copyright (C) 2006 Tower Technologies
7  * Copyright (C) 2008 Paul Mundt
8  */
9 
10 #include <linux/i2c.h>
11 #include <linux/rtc.h>
12 #include <linux/bcd.h>
13 #include <linux/slab.h>
14 #include <linux/module.h>
15 #include <linux/of_device.h>
16 
17 /*
18  * Ricoh has a family of I2C based RTCs, which differ only slightly from
19  * each other.  Differences center on pinout (e.g. how many interrupts,
20  * output clock, etc) and how the control registers are used.  The '372
21  * is significant only because that's the one this driver first supported.
22  */
23 #define RS5C372_REG_SECS	0
24 #define RS5C372_REG_MINS	1
25 #define RS5C372_REG_HOURS	2
26 #define RS5C372_REG_WDAY	3
27 #define RS5C372_REG_DAY		4
28 #define RS5C372_REG_MONTH	5
29 #define RS5C372_REG_YEAR	6
30 #define RS5C372_REG_TRIM	7
31 #	define RS5C372_TRIM_XSL		0x80
32 #	define RS5C372_TRIM_MASK	0x7F
33 
34 #define RS5C_REG_ALARM_A_MIN	8			/* or ALARM_W */
35 #define RS5C_REG_ALARM_A_HOURS	9
36 #define RS5C_REG_ALARM_A_WDAY	10
37 
38 #define RS5C_REG_ALARM_B_MIN	11			/* or ALARM_D */
39 #define RS5C_REG_ALARM_B_HOURS	12
40 #define RS5C_REG_ALARM_B_WDAY	13			/* (ALARM_B only) */
41 
42 #define RS5C_REG_CTRL1		14
43 #	define RS5C_CTRL1_AALE		(1 << 7)	/* or WALE */
44 #	define RS5C_CTRL1_BALE		(1 << 6)	/* or DALE */
45 #	define RV5C387_CTRL1_24		(1 << 5)
46 #	define RS5C372A_CTRL1_SL1	(1 << 5)
47 #	define RS5C_CTRL1_CT_MASK	(7 << 0)
48 #	define RS5C_CTRL1_CT0		(0 << 0)	/* no periodic irq */
49 #	define RS5C_CTRL1_CT4		(4 << 0)	/* 1 Hz level irq */
50 #define RS5C_REG_CTRL2		15
51 #	define RS5C372_CTRL2_24		(1 << 5)
52 #	define RS5C_CTRL2_XSTP		(1 << 4)	/* only if !R2x2x */
53 #	define R2x2x_CTRL2_VDET		(1 << 6)	/* only if  R2x2x */
54 #	define R2x2x_CTRL2_XSTP		(1 << 5)	/* only if  R2x2x */
55 #	define R2x2x_CTRL2_PON		(1 << 4)	/* only if  R2x2x */
56 #	define RS5C_CTRL2_CTFG		(1 << 2)
57 #	define RS5C_CTRL2_AAFG		(1 << 1)	/* or WAFG */
58 #	define RS5C_CTRL2_BAFG		(1 << 0)	/* or DAFG */
59 
60 
61 /* to read (style 1) or write registers starting at R */
62 #define RS5C_ADDR(R)		(((R) << 4) | 0)
63 
64 
65 enum rtc_type {
66 	rtc_undef = 0,
67 	rtc_r2025sd,
68 	rtc_r2221tl,
69 	rtc_rs5c372a,
70 	rtc_rs5c372b,
71 	rtc_rv5c386,
72 	rtc_rv5c387a,
73 };
74 
75 static const struct i2c_device_id rs5c372_id[] = {
76 	{ "r2025sd", rtc_r2025sd },
77 	{ "r2221tl", rtc_r2221tl },
78 	{ "rs5c372a", rtc_rs5c372a },
79 	{ "rs5c372b", rtc_rs5c372b },
80 	{ "rv5c386", rtc_rv5c386 },
81 	{ "rv5c387a", rtc_rv5c387a },
82 	{ }
83 };
84 MODULE_DEVICE_TABLE(i2c, rs5c372_id);
85 
86 static const __maybe_unused struct of_device_id rs5c372_of_match[] = {
87 	{
88 		.compatible = "ricoh,r2025sd",
89 		.data = (void *)rtc_r2025sd
90 	},
91 	{
92 		.compatible = "ricoh,r2221tl",
93 		.data = (void *)rtc_r2221tl
94 	},
95 	{
96 		.compatible = "ricoh,rs5c372a",
97 		.data = (void *)rtc_rs5c372a
98 	},
99 	{
100 		.compatible = "ricoh,rs5c372b",
101 		.data = (void *)rtc_rs5c372b
102 	},
103 	{
104 		.compatible = "ricoh,rv5c386",
105 		.data = (void *)rtc_rv5c386
106 	},
107 	{
108 		.compatible = "ricoh,rv5c387a",
109 		.data = (void *)rtc_rv5c387a
110 	},
111 	{ }
112 };
113 MODULE_DEVICE_TABLE(of, rs5c372_of_match);
114 
115 /* REVISIT:  this assumes that:
116  *  - we're in the 21st century, so it's safe to ignore the century
117  *    bit for rv5c38[67] (REG_MONTH bit 7);
118  *  - we should use ALARM_A not ALARM_B (may be wrong on some boards)
119  */
120 struct rs5c372 {
121 	struct i2c_client	*client;
122 	struct rtc_device	*rtc;
123 	enum rtc_type		type;
124 	unsigned		time24:1;
125 	unsigned		has_irq:1;
126 	unsigned		smbus:1;
127 	char			buf[17];
128 	char			*regs;
129 };
130 
131 static int rs5c_get_regs(struct rs5c372 *rs5c)
132 {
133 	struct i2c_client	*client = rs5c->client;
134 	struct i2c_msg		msgs[] = {
135 		{
136 			.addr = client->addr,
137 			.flags = I2C_M_RD,
138 			.len = sizeof(rs5c->buf),
139 			.buf = rs5c->buf
140 		},
141 	};
142 
143 	/* This implements the third reading method from the datasheet, using
144 	 * an internal address that's reset after each transaction (by STOP)
145 	 * to 0x0f ... so we read extra registers, and skip the first one.
146 	 *
147 	 * The first method doesn't work with the iop3xx adapter driver, on at
148 	 * least 80219 chips; this works around that bug.
149 	 *
150 	 * The third method on the other hand doesn't work for the SMBus-only
151 	 * configurations, so we use the the first method there, stripping off
152 	 * the extra register in the process.
153 	 */
154 	if (rs5c->smbus) {
155 		int addr = RS5C_ADDR(RS5C372_REG_SECS);
156 		int size = sizeof(rs5c->buf) - 1;
157 
158 		if (i2c_smbus_read_i2c_block_data(client, addr, size,
159 						  rs5c->buf + 1) != size) {
160 			dev_warn(&client->dev, "can't read registers\n");
161 			return -EIO;
162 		}
163 	} else {
164 		if ((i2c_transfer(client->adapter, msgs, 1)) != 1) {
165 			dev_warn(&client->dev, "can't read registers\n");
166 			return -EIO;
167 		}
168 	}
169 
170 	dev_dbg(&client->dev,
171 		"%3ph (%02x) %3ph (%02x), %3ph, %3ph; %02x %02x\n",
172 		rs5c->regs + 0, rs5c->regs[3],
173 		rs5c->regs + 4, rs5c->regs[7],
174 		rs5c->regs + 8, rs5c->regs + 11,
175 		rs5c->regs[14], rs5c->regs[15]);
176 
177 	return 0;
178 }
179 
180 static unsigned rs5c_reg2hr(struct rs5c372 *rs5c, unsigned reg)
181 {
182 	unsigned	hour;
183 
184 	if (rs5c->time24)
185 		return bcd2bin(reg & 0x3f);
186 
187 	hour = bcd2bin(reg & 0x1f);
188 	if (hour == 12)
189 		hour = 0;
190 	if (reg & 0x20)
191 		hour += 12;
192 	return hour;
193 }
194 
195 static unsigned rs5c_hr2reg(struct rs5c372 *rs5c, unsigned hour)
196 {
197 	if (rs5c->time24)
198 		return bin2bcd(hour);
199 
200 	if (hour > 12)
201 		return 0x20 | bin2bcd(hour - 12);
202 	if (hour == 12)
203 		return 0x20 | bin2bcd(12);
204 	if (hour == 0)
205 		return bin2bcd(12);
206 	return bin2bcd(hour);
207 }
208 
209 static int rs5c372_rtc_read_time(struct device *dev, struct rtc_time *tm)
210 {
211 	struct i2c_client *client = to_i2c_client(dev);
212 	struct rs5c372	*rs5c = i2c_get_clientdata(client);
213 	int		status = rs5c_get_regs(rs5c);
214 	unsigned char ctrl2 = rs5c->regs[RS5C_REG_CTRL2];
215 
216 	if (status < 0)
217 		return status;
218 
219 	switch (rs5c->type) {
220 	case rtc_r2025sd:
221 	case rtc_r2221tl:
222 		if ((rs5c->type == rtc_r2025sd && !(ctrl2 & R2x2x_CTRL2_XSTP)) ||
223 		    (rs5c->type == rtc_r2221tl &&  (ctrl2 & R2x2x_CTRL2_XSTP))) {
224 			dev_warn(&client->dev, "rtc oscillator interruption detected. Please reset the rtc clock.\n");
225 			return -EINVAL;
226 		}
227 		break;
228 	default:
229 		if (ctrl2 & RS5C_CTRL2_XSTP) {
230 			dev_warn(&client->dev, "rtc oscillator interruption detected. Please reset the rtc clock.\n");
231 			return -EINVAL;
232 		}
233 	}
234 
235 	tm->tm_sec = bcd2bin(rs5c->regs[RS5C372_REG_SECS] & 0x7f);
236 	tm->tm_min = bcd2bin(rs5c->regs[RS5C372_REG_MINS] & 0x7f);
237 	tm->tm_hour = rs5c_reg2hr(rs5c, rs5c->regs[RS5C372_REG_HOURS]);
238 
239 	tm->tm_wday = bcd2bin(rs5c->regs[RS5C372_REG_WDAY] & 0x07);
240 	tm->tm_mday = bcd2bin(rs5c->regs[RS5C372_REG_DAY] & 0x3f);
241 
242 	/* tm->tm_mon is zero-based */
243 	tm->tm_mon = bcd2bin(rs5c->regs[RS5C372_REG_MONTH] & 0x1f) - 1;
244 
245 	/* year is 1900 + tm->tm_year */
246 	tm->tm_year = bcd2bin(rs5c->regs[RS5C372_REG_YEAR]) + 100;
247 
248 	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
249 		"mday=%d, mon=%d, year=%d, wday=%d\n",
250 		__func__,
251 		tm->tm_sec, tm->tm_min, tm->tm_hour,
252 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
253 
254 	return 0;
255 }
256 
257 static int rs5c372_rtc_set_time(struct device *dev, struct rtc_time *tm)
258 {
259 	struct i2c_client *client = to_i2c_client(dev);
260 	struct rs5c372	*rs5c = i2c_get_clientdata(client);
261 	unsigned char	buf[7];
262 	unsigned char	ctrl2;
263 	int		addr;
264 
265 	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d "
266 		"mday=%d, mon=%d, year=%d, wday=%d\n",
267 		__func__,
268 		tm->tm_sec, tm->tm_min, tm->tm_hour,
269 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
270 
271 	addr   = RS5C_ADDR(RS5C372_REG_SECS);
272 	buf[0] = bin2bcd(tm->tm_sec);
273 	buf[1] = bin2bcd(tm->tm_min);
274 	buf[2] = rs5c_hr2reg(rs5c, tm->tm_hour);
275 	buf[3] = bin2bcd(tm->tm_wday);
276 	buf[4] = bin2bcd(tm->tm_mday);
277 	buf[5] = bin2bcd(tm->tm_mon + 1);
278 	buf[6] = bin2bcd(tm->tm_year - 100);
279 
280 	if (i2c_smbus_write_i2c_block_data(client, addr, sizeof(buf), buf) < 0) {
281 		dev_dbg(&client->dev, "%s: write error in line %i\n",
282 			__func__, __LINE__);
283 		return -EIO;
284 	}
285 
286 	addr = RS5C_ADDR(RS5C_REG_CTRL2);
287 	ctrl2 = i2c_smbus_read_byte_data(client, addr);
288 
289 	/* clear rtc warning bits */
290 	switch (rs5c->type) {
291 	case rtc_r2025sd:
292 	case rtc_r2221tl:
293 		ctrl2 &= ~(R2x2x_CTRL2_VDET | R2x2x_CTRL2_PON);
294 		if (rs5c->type == rtc_r2025sd)
295 			ctrl2 |= R2x2x_CTRL2_XSTP;
296 		else
297 			ctrl2 &= ~R2x2x_CTRL2_XSTP;
298 		break;
299 	default:
300 		ctrl2 &= ~RS5C_CTRL2_XSTP;
301 		break;
302 	}
303 
304 	if (i2c_smbus_write_byte_data(client, addr, ctrl2) < 0) {
305 		dev_dbg(&client->dev, "%s: write error in line %i\n",
306 			__func__, __LINE__);
307 		return -EIO;
308 	}
309 
310 	return 0;
311 }
312 
313 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
314 #define	NEED_TRIM
315 #endif
316 
317 #if IS_ENABLED(CONFIG_RTC_INTF_SYSFS)
318 #define	NEED_TRIM
319 #endif
320 
321 #ifdef	NEED_TRIM
322 static int rs5c372_get_trim(struct i2c_client *client, int *osc, int *trim)
323 {
324 	struct rs5c372 *rs5c372 = i2c_get_clientdata(client);
325 	u8 tmp = rs5c372->regs[RS5C372_REG_TRIM];
326 
327 	if (osc)
328 		*osc = (tmp & RS5C372_TRIM_XSL) ? 32000 : 32768;
329 
330 	if (trim) {
331 		dev_dbg(&client->dev, "%s: raw trim=%x\n", __func__, tmp);
332 		tmp &= RS5C372_TRIM_MASK;
333 		if (tmp & 0x3e) {
334 			int t = tmp & 0x3f;
335 
336 			if (tmp & 0x40)
337 				t = (~t | (s8)0xc0) + 1;
338 			else
339 				t = t - 1;
340 
341 			tmp = t * 2;
342 		} else
343 			tmp = 0;
344 		*trim = tmp;
345 	}
346 
347 	return 0;
348 }
349 #endif
350 
351 static int rs5c_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
352 {
353 	struct i2c_client	*client = to_i2c_client(dev);
354 	struct rs5c372		*rs5c = i2c_get_clientdata(client);
355 	unsigned char		buf;
356 	int			status, addr;
357 
358 	buf = rs5c->regs[RS5C_REG_CTRL1];
359 
360 	if (!rs5c->has_irq)
361 		return -EINVAL;
362 
363 	status = rs5c_get_regs(rs5c);
364 	if (status < 0)
365 		return status;
366 
367 	addr = RS5C_ADDR(RS5C_REG_CTRL1);
368 	if (enabled)
369 		buf |= RS5C_CTRL1_AALE;
370 	else
371 		buf &= ~RS5C_CTRL1_AALE;
372 
373 	if (i2c_smbus_write_byte_data(client, addr, buf) < 0) {
374 		dev_warn(dev, "can't update alarm\n");
375 		status = -EIO;
376 	} else
377 		rs5c->regs[RS5C_REG_CTRL1] = buf;
378 
379 	return status;
380 }
381 
382 
383 /* NOTE:  Since RTC_WKALM_{RD,SET} were originally defined for EFI,
384  * which only exposes a polled programming interface; and since
385  * these calls map directly to those EFI requests; we don't demand
386  * we have an IRQ for this chip when we go through this API.
387  *
388  * The older x86_pc derived RTC_ALM_{READ,SET} calls require irqs
389  * though, managed through RTC_AIE_{ON,OFF} requests.
390  */
391 
392 static int rs5c_read_alarm(struct device *dev, struct rtc_wkalrm *t)
393 {
394 	struct i2c_client	*client = to_i2c_client(dev);
395 	struct rs5c372		*rs5c = i2c_get_clientdata(client);
396 	int			status;
397 
398 	status = rs5c_get_regs(rs5c);
399 	if (status < 0)
400 		return status;
401 
402 	/* report alarm time */
403 	t->time.tm_sec = 0;
404 	t->time.tm_min = bcd2bin(rs5c->regs[RS5C_REG_ALARM_A_MIN] & 0x7f);
405 	t->time.tm_hour = rs5c_reg2hr(rs5c, rs5c->regs[RS5C_REG_ALARM_A_HOURS]);
406 
407 	/* ... and status */
408 	t->enabled = !!(rs5c->regs[RS5C_REG_CTRL1] & RS5C_CTRL1_AALE);
409 	t->pending = !!(rs5c->regs[RS5C_REG_CTRL2] & RS5C_CTRL2_AAFG);
410 
411 	return 0;
412 }
413 
414 static int rs5c_set_alarm(struct device *dev, struct rtc_wkalrm *t)
415 {
416 	struct i2c_client	*client = to_i2c_client(dev);
417 	struct rs5c372		*rs5c = i2c_get_clientdata(client);
418 	int			status, addr, i;
419 	unsigned char		buf[3];
420 
421 	/* only handle up to 24 hours in the future, like RTC_ALM_SET */
422 	if (t->time.tm_mday != -1
423 			|| t->time.tm_mon != -1
424 			|| t->time.tm_year != -1)
425 		return -EINVAL;
426 
427 	/* REVISIT: round up tm_sec */
428 
429 	/* if needed, disable irq (clears pending status) */
430 	status = rs5c_get_regs(rs5c);
431 	if (status < 0)
432 		return status;
433 	if (rs5c->regs[RS5C_REG_CTRL1] & RS5C_CTRL1_AALE) {
434 		addr = RS5C_ADDR(RS5C_REG_CTRL1);
435 		buf[0] = rs5c->regs[RS5C_REG_CTRL1] & ~RS5C_CTRL1_AALE;
436 		if (i2c_smbus_write_byte_data(client, addr, buf[0]) < 0) {
437 			dev_dbg(dev, "can't disable alarm\n");
438 			return -EIO;
439 		}
440 		rs5c->regs[RS5C_REG_CTRL1] = buf[0];
441 	}
442 
443 	/* set alarm */
444 	buf[0] = bin2bcd(t->time.tm_min);
445 	buf[1] = rs5c_hr2reg(rs5c, t->time.tm_hour);
446 	buf[2] = 0x7f;	/* any/all days */
447 
448 	for (i = 0; i < sizeof(buf); i++) {
449 		addr = RS5C_ADDR(RS5C_REG_ALARM_A_MIN + i);
450 		if (i2c_smbus_write_byte_data(client, addr, buf[i]) < 0) {
451 			dev_dbg(dev, "can't set alarm time\n");
452 			return -EIO;
453 		}
454 	}
455 
456 	/* ... and maybe enable its irq */
457 	if (t->enabled) {
458 		addr = RS5C_ADDR(RS5C_REG_CTRL1);
459 		buf[0] = rs5c->regs[RS5C_REG_CTRL1] | RS5C_CTRL1_AALE;
460 		if (i2c_smbus_write_byte_data(client, addr, buf[0]) < 0)
461 			dev_warn(dev, "can't enable alarm\n");
462 		rs5c->regs[RS5C_REG_CTRL1] = buf[0];
463 	}
464 
465 	return 0;
466 }
467 
468 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
469 
470 static int rs5c372_rtc_proc(struct device *dev, struct seq_file *seq)
471 {
472 	int err, osc, trim;
473 
474 	err = rs5c372_get_trim(to_i2c_client(dev), &osc, &trim);
475 	if (err == 0) {
476 		seq_printf(seq, "crystal\t\t: %d.%03d KHz\n",
477 				osc / 1000, osc % 1000);
478 		seq_printf(seq, "trim\t\t: %d\n", trim);
479 	}
480 
481 	return 0;
482 }
483 
484 #else
485 #define	rs5c372_rtc_proc	NULL
486 #endif
487 
488 static const struct rtc_class_ops rs5c372_rtc_ops = {
489 	.proc		= rs5c372_rtc_proc,
490 	.read_time	= rs5c372_rtc_read_time,
491 	.set_time	= rs5c372_rtc_set_time,
492 	.read_alarm	= rs5c_read_alarm,
493 	.set_alarm	= rs5c_set_alarm,
494 	.alarm_irq_enable = rs5c_rtc_alarm_irq_enable,
495 };
496 
497 #if IS_ENABLED(CONFIG_RTC_INTF_SYSFS)
498 
499 static ssize_t rs5c372_sysfs_show_trim(struct device *dev,
500 				struct device_attribute *attr, char *buf)
501 {
502 	int err, trim;
503 
504 	err = rs5c372_get_trim(to_i2c_client(dev), NULL, &trim);
505 	if (err)
506 		return err;
507 
508 	return sprintf(buf, "%d\n", trim);
509 }
510 static DEVICE_ATTR(trim, S_IRUGO, rs5c372_sysfs_show_trim, NULL);
511 
512 static ssize_t rs5c372_sysfs_show_osc(struct device *dev,
513 				struct device_attribute *attr, char *buf)
514 {
515 	int err, osc;
516 
517 	err = rs5c372_get_trim(to_i2c_client(dev), &osc, NULL);
518 	if (err)
519 		return err;
520 
521 	return sprintf(buf, "%d.%03d KHz\n", osc / 1000, osc % 1000);
522 }
523 static DEVICE_ATTR(osc, S_IRUGO, rs5c372_sysfs_show_osc, NULL);
524 
525 static int rs5c_sysfs_register(struct device *dev)
526 {
527 	int err;
528 
529 	err = device_create_file(dev, &dev_attr_trim);
530 	if (err)
531 		return err;
532 	err = device_create_file(dev, &dev_attr_osc);
533 	if (err)
534 		device_remove_file(dev, &dev_attr_trim);
535 
536 	return err;
537 }
538 
539 static void rs5c_sysfs_unregister(struct device *dev)
540 {
541 	device_remove_file(dev, &dev_attr_trim);
542 	device_remove_file(dev, &dev_attr_osc);
543 }
544 
545 #else
546 static int rs5c_sysfs_register(struct device *dev)
547 {
548 	return 0;
549 }
550 
551 static void rs5c_sysfs_unregister(struct device *dev)
552 {
553 	/* nothing */
554 }
555 #endif	/* SYSFS */
556 
557 static struct i2c_driver rs5c372_driver;
558 
559 static int rs5c_oscillator_setup(struct rs5c372 *rs5c372)
560 {
561 	unsigned char buf[2];
562 	int addr, i, ret = 0;
563 
564 	addr   = RS5C_ADDR(RS5C_REG_CTRL1);
565 	buf[0] = rs5c372->regs[RS5C_REG_CTRL1];
566 	buf[1] = rs5c372->regs[RS5C_REG_CTRL2];
567 
568 	switch (rs5c372->type) {
569 	case rtc_r2025sd:
570 		if (buf[1] & R2x2x_CTRL2_XSTP)
571 			return ret;
572 		break;
573 	case rtc_r2221tl:
574 		if (!(buf[1] & R2x2x_CTRL2_XSTP))
575 			return ret;
576 		break;
577 	default:
578 		if (!(buf[1] & RS5C_CTRL2_XSTP))
579 			return ret;
580 		break;
581 	}
582 
583 	/* use 24hr mode */
584 	switch (rs5c372->type) {
585 	case rtc_rs5c372a:
586 	case rtc_rs5c372b:
587 		buf[1] |= RS5C372_CTRL2_24;
588 		rs5c372->time24 = 1;
589 		break;
590 	case rtc_r2025sd:
591 	case rtc_r2221tl:
592 	case rtc_rv5c386:
593 	case rtc_rv5c387a:
594 		buf[0] |= RV5C387_CTRL1_24;
595 		rs5c372->time24 = 1;
596 		break;
597 	default:
598 		/* impossible */
599 		break;
600 	}
601 
602 	for (i = 0; i < sizeof(buf); i++) {
603 		addr = RS5C_ADDR(RS5C_REG_CTRL1 + i);
604 		ret = i2c_smbus_write_byte_data(rs5c372->client, addr, buf[i]);
605 		if (unlikely(ret < 0))
606 			return ret;
607 	}
608 
609 	rs5c372->regs[RS5C_REG_CTRL1] = buf[0];
610 	rs5c372->regs[RS5C_REG_CTRL2] = buf[1];
611 
612 	return 0;
613 }
614 
615 static int rs5c372_probe(struct i2c_client *client,
616 			 const struct i2c_device_id *id)
617 {
618 	int err = 0;
619 	int smbus_mode = 0;
620 	struct rs5c372 *rs5c372;
621 
622 	dev_dbg(&client->dev, "%s\n", __func__);
623 
624 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
625 			I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK)) {
626 		/*
627 		 * If we don't have any master mode adapter, try breaking
628 		 * it down in to the barest of capabilities.
629 		 */
630 		if (i2c_check_functionality(client->adapter,
631 				I2C_FUNC_SMBUS_BYTE_DATA |
632 				I2C_FUNC_SMBUS_I2C_BLOCK))
633 			smbus_mode = 1;
634 		else {
635 			/* Still no good, give up */
636 			err = -ENODEV;
637 			goto exit;
638 		}
639 	}
640 
641 	rs5c372 = devm_kzalloc(&client->dev, sizeof(struct rs5c372),
642 				GFP_KERNEL);
643 	if (!rs5c372) {
644 		err = -ENOMEM;
645 		goto exit;
646 	}
647 
648 	rs5c372->client = client;
649 	i2c_set_clientdata(client, rs5c372);
650 	if (client->dev.of_node)
651 		rs5c372->type = (enum rtc_type)
652 			of_device_get_match_data(&client->dev);
653 	else
654 		rs5c372->type = id->driver_data;
655 
656 	/* we read registers 0x0f then 0x00-0x0f; skip the first one */
657 	rs5c372->regs = &rs5c372->buf[1];
658 	rs5c372->smbus = smbus_mode;
659 
660 	err = rs5c_get_regs(rs5c372);
661 	if (err < 0)
662 		goto exit;
663 
664 	/* clock may be set for am/pm or 24 hr time */
665 	switch (rs5c372->type) {
666 	case rtc_rs5c372a:
667 	case rtc_rs5c372b:
668 		/* alarm uses ALARM_A; and nINTRA on 372a, nINTR on 372b.
669 		 * so does periodic irq, except some 327a modes.
670 		 */
671 		if (rs5c372->regs[RS5C_REG_CTRL2] & RS5C372_CTRL2_24)
672 			rs5c372->time24 = 1;
673 		break;
674 	case rtc_r2025sd:
675 	case rtc_r2221tl:
676 	case rtc_rv5c386:
677 	case rtc_rv5c387a:
678 		if (rs5c372->regs[RS5C_REG_CTRL1] & RV5C387_CTRL1_24)
679 			rs5c372->time24 = 1;
680 		/* alarm uses ALARM_W; and nINTRB for alarm and periodic
681 		 * irq, on both 386 and 387
682 		 */
683 		break;
684 	default:
685 		dev_err(&client->dev, "unknown RTC type\n");
686 		goto exit;
687 	}
688 
689 	/* if the oscillator lost power and no other software (like
690 	 * the bootloader) set it up, do it here.
691 	 *
692 	 * The R2025S/D does this a little differently than the other
693 	 * parts, so we special case that..
694 	 */
695 	err = rs5c_oscillator_setup(rs5c372);
696 	if (unlikely(err < 0)) {
697 		dev_err(&client->dev, "setup error\n");
698 		goto exit;
699 	}
700 
701 	dev_info(&client->dev, "%s found, %s\n",
702 			({ char *s; switch (rs5c372->type) {
703 			case rtc_r2025sd:	s = "r2025sd"; break;
704 			case rtc_r2221tl:	s = "r2221tl"; break;
705 			case rtc_rs5c372a:	s = "rs5c372a"; break;
706 			case rtc_rs5c372b:	s = "rs5c372b"; break;
707 			case rtc_rv5c386:	s = "rv5c386"; break;
708 			case rtc_rv5c387a:	s = "rv5c387a"; break;
709 			default:		s = "chip"; break;
710 			}; s;}),
711 			rs5c372->time24 ? "24hr" : "am/pm"
712 			);
713 
714 	/* REVISIT use client->irq to register alarm irq ... */
715 	rs5c372->rtc = devm_rtc_device_register(&client->dev,
716 					rs5c372_driver.driver.name,
717 					&rs5c372_rtc_ops, THIS_MODULE);
718 
719 	if (IS_ERR(rs5c372->rtc)) {
720 		err = PTR_ERR(rs5c372->rtc);
721 		goto exit;
722 	}
723 
724 	err = rs5c_sysfs_register(&client->dev);
725 	if (err)
726 		goto exit;
727 
728 	return 0;
729 
730 exit:
731 	return err;
732 }
733 
734 static int rs5c372_remove(struct i2c_client *client)
735 {
736 	rs5c_sysfs_unregister(&client->dev);
737 	return 0;
738 }
739 
740 static struct i2c_driver rs5c372_driver = {
741 	.driver		= {
742 		.name	= "rtc-rs5c372",
743 		.of_match_table = of_match_ptr(rs5c372_of_match),
744 	},
745 	.probe		= rs5c372_probe,
746 	.remove		= rs5c372_remove,
747 	.id_table	= rs5c372_id,
748 };
749 
750 module_i2c_driver(rs5c372_driver);
751 
752 MODULE_AUTHOR(
753 		"Pavel Mironchik <pmironchik@optifacio.net>, "
754 		"Alessandro Zummo <a.zummo@towertech.it>, "
755 		"Paul Mundt <lethal@linux-sh.org>");
756 MODULE_DESCRIPTION("Ricoh RS5C372 RTC driver");
757 MODULE_LICENSE("GPL");
758