1 /*
2  * Seiko Instruments S-35390A RTC Driver
3  *
4  * Copyright (c) 2007 Byron Bradley
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  */
11 
12 #include <linux/module.h>
13 #include <linux/rtc.h>
14 #include <linux/i2c.h>
15 #include <linux/bitrev.h>
16 #include <linux/bcd.h>
17 #include <linux/slab.h>
18 #include <linux/delay.h>
19 
20 #define S35390A_CMD_STATUS1	0
21 #define S35390A_CMD_STATUS2	1
22 #define S35390A_CMD_TIME1	2
23 #define S35390A_CMD_TIME2	3
24 #define S35390A_CMD_INT2_REG1	5
25 
26 #define S35390A_BYTE_YEAR	0
27 #define S35390A_BYTE_MONTH	1
28 #define S35390A_BYTE_DAY	2
29 #define S35390A_BYTE_WDAY	3
30 #define S35390A_BYTE_HOURS	4
31 #define S35390A_BYTE_MINS	5
32 #define S35390A_BYTE_SECS	6
33 
34 #define S35390A_ALRM_BYTE_WDAY	0
35 #define S35390A_ALRM_BYTE_HOURS	1
36 #define S35390A_ALRM_BYTE_MINS	2
37 
38 /* flags for STATUS1 */
39 #define S35390A_FLAG_POC	0x01
40 #define S35390A_FLAG_BLD	0x02
41 #define S35390A_FLAG_INT2	0x04
42 #define S35390A_FLAG_24H	0x40
43 #define S35390A_FLAG_RESET	0x80
44 
45 /* flag for STATUS2 */
46 #define S35390A_FLAG_TEST	0x01
47 
48 #define S35390A_INT2_MODE_MASK		0xF0
49 
50 #define S35390A_INT2_MODE_NOINTR	0x00
51 #define S35390A_INT2_MODE_FREQ		0x10
52 #define S35390A_INT2_MODE_ALARM		0x40
53 #define S35390A_INT2_MODE_PMIN_EDG	0x20
54 
55 static const struct i2c_device_id s35390a_id[] = {
56 	{ "s35390a", 0 },
57 	{ }
58 };
59 MODULE_DEVICE_TABLE(i2c, s35390a_id);
60 
61 static const struct of_device_id s35390a_of_match[] = {
62 	{ .compatible = "s35390a" },
63 	{ .compatible = "sii,s35390a" },
64 	{ }
65 };
66 MODULE_DEVICE_TABLE(of, s35390a_of_match);
67 
68 struct s35390a {
69 	struct i2c_client *client[8];
70 	struct rtc_device *rtc;
71 	int twentyfourhour;
72 };
73 
s35390a_set_reg(struct s35390a * s35390a,int reg,char * buf,int len)74 static int s35390a_set_reg(struct s35390a *s35390a, int reg, char *buf, int len)
75 {
76 	struct i2c_client *client = s35390a->client[reg];
77 	struct i2c_msg msg[] = {
78 		{
79 			.addr = client->addr,
80 			.len = len,
81 			.buf = buf
82 		},
83 	};
84 
85 	if ((i2c_transfer(client->adapter, msg, 1)) != 1)
86 		return -EIO;
87 
88 	return 0;
89 }
90 
s35390a_get_reg(struct s35390a * s35390a,int reg,char * buf,int len)91 static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *buf, int len)
92 {
93 	struct i2c_client *client = s35390a->client[reg];
94 	struct i2c_msg msg[] = {
95 		{
96 			.addr = client->addr,
97 			.flags = I2C_M_RD,
98 			.len = len,
99 			.buf = buf
100 		},
101 	};
102 
103 	if ((i2c_transfer(client->adapter, msg, 1)) != 1)
104 		return -EIO;
105 
106 	return 0;
107 }
108 
s35390a_init(struct s35390a * s35390a)109 static int s35390a_init(struct s35390a *s35390a)
110 {
111 	u8 buf;
112 	int ret;
113 	unsigned initcount = 0;
114 
115 	/*
116 	 * At least one of POC and BLD are set, so reinitialise chip. Keeping
117 	 * this information in the hardware to know later that the time isn't
118 	 * valid is unfortunately not possible because POC and BLD are cleared
119 	 * on read. So the reset is best done now.
120 	 *
121 	 * The 24H bit is kept over reset, so set it already here.
122 	 */
123 initialize:
124 	buf = S35390A_FLAG_RESET | S35390A_FLAG_24H;
125 	ret = s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
126 
127 	if (ret < 0)
128 		return ret;
129 
130 	ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
131 	if (ret < 0)
132 		return ret;
133 
134 	if (buf & (S35390A_FLAG_POC | S35390A_FLAG_BLD)) {
135 		/* Try up to five times to reset the chip */
136 		if (initcount < 5) {
137 			++initcount;
138 			goto initialize;
139 		} else
140 			return -EIO;
141 	}
142 
143 	return 1;
144 }
145 
146 /*
147  * Returns <0 on error, 0 if rtc is setup fine and 1 if the chip was reset.
148  * To keep the information if an irq is pending, pass the value read from
149  * STATUS1 to the caller.
150  */
s35390a_read_status(struct s35390a * s35390a,char * status1)151 static int s35390a_read_status(struct s35390a *s35390a, char *status1)
152 {
153 	int ret;
154 
155 	ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, status1, 1);
156 	if (ret < 0)
157 		return ret;
158 
159 	if (*status1 & S35390A_FLAG_POC) {
160 		/*
161 		 * Do not communicate for 0.5 seconds since the power-on
162 		 * detection circuit is in operation.
163 		 */
164 		msleep(500);
165 		return 1;
166 	} else if (*status1 & S35390A_FLAG_BLD)
167 		return 1;
168 	/*
169 	 * If both POC and BLD are unset everything is fine.
170 	 */
171 	return 0;
172 }
173 
s35390a_disable_test_mode(struct s35390a * s35390a)174 static int s35390a_disable_test_mode(struct s35390a *s35390a)
175 {
176 	char buf[1];
177 
178 	if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf)) < 0)
179 		return -EIO;
180 
181 	if (!(buf[0] & S35390A_FLAG_TEST))
182 		return 0;
183 
184 	buf[0] &= ~S35390A_FLAG_TEST;
185 	return s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf));
186 }
187 
s35390a_hr2reg(struct s35390a * s35390a,int hour)188 static char s35390a_hr2reg(struct s35390a *s35390a, int hour)
189 {
190 	if (s35390a->twentyfourhour)
191 		return bin2bcd(hour);
192 
193 	if (hour < 12)
194 		return bin2bcd(hour);
195 
196 	return 0x40 | bin2bcd(hour - 12);
197 }
198 
s35390a_reg2hr(struct s35390a * s35390a,char reg)199 static int s35390a_reg2hr(struct s35390a *s35390a, char reg)
200 {
201 	unsigned hour;
202 
203 	if (s35390a->twentyfourhour)
204 		return bcd2bin(reg & 0x3f);
205 
206 	hour = bcd2bin(reg & 0x3f);
207 	if (reg & 0x40)
208 		hour += 12;
209 
210 	return hour;
211 }
212 
s35390a_rtc_set_time(struct device * dev,struct rtc_time * tm)213 static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
214 {
215 	struct i2c_client *client = to_i2c_client(dev);
216 	struct s35390a	*s35390a = i2c_get_clientdata(client);
217 	int i, err;
218 	char buf[7], status;
219 
220 	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d mday=%d, "
221 		"mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
222 		tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
223 		tm->tm_wday);
224 
225 	if (s35390a_read_status(s35390a, &status) == 1)
226 		s35390a_init(s35390a);
227 
228 	buf[S35390A_BYTE_YEAR] = bin2bcd(tm->tm_year - 100);
229 	buf[S35390A_BYTE_MONTH] = bin2bcd(tm->tm_mon + 1);
230 	buf[S35390A_BYTE_DAY] = bin2bcd(tm->tm_mday);
231 	buf[S35390A_BYTE_WDAY] = bin2bcd(tm->tm_wday);
232 	buf[S35390A_BYTE_HOURS] = s35390a_hr2reg(s35390a, tm->tm_hour);
233 	buf[S35390A_BYTE_MINS] = bin2bcd(tm->tm_min);
234 	buf[S35390A_BYTE_SECS] = bin2bcd(tm->tm_sec);
235 
236 	/* This chip expects the bits of each byte to be in reverse order */
237 	for (i = 0; i < 7; ++i)
238 		buf[i] = bitrev8(buf[i]);
239 
240 	err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
241 
242 	return err;
243 }
244 
s35390a_rtc_read_time(struct device * dev,struct rtc_time * tm)245 static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
246 {
247 	struct i2c_client *client = to_i2c_client(dev);
248 	struct s35390a *s35390a = i2c_get_clientdata(client);
249 	char buf[7], status;
250 	int i, err;
251 
252 	if (s35390a_read_status(s35390a, &status) == 1)
253 		return -EINVAL;
254 
255 	err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
256 	if (err < 0)
257 		return err;
258 
259 	/* This chip returns the bits of each byte in reverse order */
260 	for (i = 0; i < 7; ++i)
261 		buf[i] = bitrev8(buf[i]);
262 
263 	tm->tm_sec = bcd2bin(buf[S35390A_BYTE_SECS]);
264 	tm->tm_min = bcd2bin(buf[S35390A_BYTE_MINS]);
265 	tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
266 	tm->tm_wday = bcd2bin(buf[S35390A_BYTE_WDAY]);
267 	tm->tm_mday = bcd2bin(buf[S35390A_BYTE_DAY]);
268 	tm->tm_mon = bcd2bin(buf[S35390A_BYTE_MONTH]) - 1;
269 	tm->tm_year = bcd2bin(buf[S35390A_BYTE_YEAR]) + 100;
270 
271 	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, mday=%d, "
272 		"mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
273 		tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
274 		tm->tm_wday);
275 
276 	return 0;
277 }
278 
s35390a_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alm)279 static int s35390a_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
280 {
281 	struct i2c_client *client = to_i2c_client(dev);
282 	struct s35390a *s35390a = i2c_get_clientdata(client);
283 	char buf[3], sts = 0;
284 	int err, i;
285 
286 	dev_dbg(&client->dev, "%s: alm is secs=%d, mins=%d, hours=%d mday=%d, "\
287 		"mon=%d, year=%d, wday=%d\n", __func__, alm->time.tm_sec,
288 		alm->time.tm_min, alm->time.tm_hour, alm->time.tm_mday,
289 		alm->time.tm_mon, alm->time.tm_year, alm->time.tm_wday);
290 
291 	/* disable interrupt (which deasserts the irq line) */
292 	err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
293 	if (err < 0)
294 		return err;
295 
296 	/* clear pending interrupt (in STATUS1 only), if any */
297 	err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &sts, sizeof(sts));
298 	if (err < 0)
299 		return err;
300 
301 	if (alm->enabled)
302 		sts = S35390A_INT2_MODE_ALARM;
303 	else
304 		sts = S35390A_INT2_MODE_NOINTR;
305 
306 	/* This chip expects the bits of each byte to be in reverse order */
307 	sts = bitrev8(sts);
308 
309 	/* set interupt mode*/
310 	err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
311 	if (err < 0)
312 		return err;
313 
314 	if (alm->time.tm_wday != -1)
315 		buf[S35390A_ALRM_BYTE_WDAY] = bin2bcd(alm->time.tm_wday) | 0x80;
316 	else
317 		buf[S35390A_ALRM_BYTE_WDAY] = 0;
318 
319 	buf[S35390A_ALRM_BYTE_HOURS] = s35390a_hr2reg(s35390a,
320 			alm->time.tm_hour) | 0x80;
321 	buf[S35390A_ALRM_BYTE_MINS] = bin2bcd(alm->time.tm_min) | 0x80;
322 
323 	if (alm->time.tm_hour >= 12)
324 		buf[S35390A_ALRM_BYTE_HOURS] |= 0x40;
325 
326 	for (i = 0; i < 3; ++i)
327 		buf[i] = bitrev8(buf[i]);
328 
329 	err = s35390a_set_reg(s35390a, S35390A_CMD_INT2_REG1, buf,
330 								sizeof(buf));
331 
332 	return err;
333 }
334 
s35390a_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alm)335 static int s35390a_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
336 {
337 	struct i2c_client *client = to_i2c_client(dev);
338 	struct s35390a *s35390a = i2c_get_clientdata(client);
339 	char buf[3], sts;
340 	int i, err;
341 
342 	err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
343 	if (err < 0)
344 		return err;
345 
346 	if ((bitrev8(sts) & S35390A_INT2_MODE_MASK) != S35390A_INT2_MODE_ALARM) {
347 		/*
348 		 * When the alarm isn't enabled, the register to configure
349 		 * the alarm time isn't accessible.
350 		 */
351 		alm->enabled = 0;
352 		return 0;
353 	} else {
354 		alm->enabled = 1;
355 	}
356 
357 	err = s35390a_get_reg(s35390a, S35390A_CMD_INT2_REG1, buf, sizeof(buf));
358 	if (err < 0)
359 		return err;
360 
361 	/* This chip returns the bits of each byte in reverse order */
362 	for (i = 0; i < 3; ++i)
363 		buf[i] = bitrev8(buf[i]);
364 
365 	/*
366 	 * B0 of the three matching registers is an enable flag. Iff it is set
367 	 * the configured value is used for matching.
368 	 */
369 	if (buf[S35390A_ALRM_BYTE_WDAY] & 0x80)
370 		alm->time.tm_wday =
371 			bcd2bin(buf[S35390A_ALRM_BYTE_WDAY] & ~0x80);
372 
373 	if (buf[S35390A_ALRM_BYTE_HOURS] & 0x80)
374 		alm->time.tm_hour =
375 			s35390a_reg2hr(s35390a,
376 				       buf[S35390A_ALRM_BYTE_HOURS] & ~0x80);
377 
378 	if (buf[S35390A_ALRM_BYTE_MINS] & 0x80)
379 		alm->time.tm_min = bcd2bin(buf[S35390A_ALRM_BYTE_MINS] & ~0x80);
380 
381 	/* alarm triggers always at s=0 */
382 	alm->time.tm_sec = 0;
383 
384 	dev_dbg(&client->dev, "%s: alm is mins=%d, hours=%d, wday=%d\n",
385 			__func__, alm->time.tm_min, alm->time.tm_hour,
386 			alm->time.tm_wday);
387 
388 	return 0;
389 }
390 
s35390a_rtc_ioctl(struct device * dev,unsigned int cmd,unsigned long arg)391 static int s35390a_rtc_ioctl(struct device *dev, unsigned int cmd,
392 			     unsigned long arg)
393 {
394 	struct i2c_client *client = to_i2c_client(dev);
395 	struct s35390a *s35390a = i2c_get_clientdata(client);
396 	char sts;
397 	int err;
398 
399 	switch (cmd) {
400 	case RTC_VL_READ:
401 		/* s35390a_reset set lowvoltage flag and init RTC if needed */
402 		err = s35390a_read_status(s35390a, &sts);
403 		if (err < 0)
404 			return err;
405 		if (copy_to_user((void __user *)arg, &err, sizeof(int)))
406 			return -EFAULT;
407 		break;
408 	case RTC_VL_CLR:
409 		/* update flag and clear register */
410 		err = s35390a_init(s35390a);
411 		if (err < 0)
412 			return err;
413 		break;
414 	default:
415 		return -ENOIOCTLCMD;
416 	}
417 
418 	return 0;
419 }
420 
421 static const struct rtc_class_ops s35390a_rtc_ops = {
422 	.read_time	= s35390a_rtc_read_time,
423 	.set_time	= s35390a_rtc_set_time,
424 	.set_alarm	= s35390a_rtc_set_alarm,
425 	.read_alarm	= s35390a_rtc_read_alarm,
426 	.ioctl          = s35390a_rtc_ioctl,
427 };
428 
429 static struct i2c_driver s35390a_driver;
430 
s35390a_probe(struct i2c_client * client,const struct i2c_device_id * id)431 static int s35390a_probe(struct i2c_client *client,
432 			 const struct i2c_device_id *id)
433 {
434 	int err, err_read;
435 	unsigned int i;
436 	struct s35390a *s35390a;
437 	char buf, status1;
438 
439 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
440 		err = -ENODEV;
441 		goto exit;
442 	}
443 
444 	s35390a = devm_kzalloc(&client->dev, sizeof(struct s35390a),
445 				GFP_KERNEL);
446 	if (!s35390a) {
447 		err = -ENOMEM;
448 		goto exit;
449 	}
450 
451 	s35390a->client[0] = client;
452 	i2c_set_clientdata(client, s35390a);
453 
454 	/* This chip uses multiple addresses, use dummy devices for them */
455 	for (i = 1; i < 8; ++i) {
456 		s35390a->client[i] = i2c_new_dummy(client->adapter,
457 					client->addr + i);
458 		if (!s35390a->client[i]) {
459 			dev_err(&client->dev, "Address %02x unavailable\n",
460 						client->addr + i);
461 			err = -EBUSY;
462 			goto exit_dummy;
463 		}
464 	}
465 
466 	err_read = s35390a_read_status(s35390a, &status1);
467 	if (err_read < 0) {
468 		err = err_read;
469 		dev_err(&client->dev, "error resetting chip\n");
470 		goto exit_dummy;
471 	}
472 
473 	if (status1 & S35390A_FLAG_24H)
474 		s35390a->twentyfourhour = 1;
475 	else
476 		s35390a->twentyfourhour = 0;
477 
478 	if (status1 & S35390A_FLAG_INT2) {
479 		/* disable alarm (and maybe test mode) */
480 		buf = 0;
481 		err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &buf, 1);
482 		if (err < 0) {
483 			dev_err(&client->dev, "error disabling alarm");
484 			goto exit_dummy;
485 		}
486 	} else {
487 		err = s35390a_disable_test_mode(s35390a);
488 		if (err < 0) {
489 			dev_err(&client->dev, "error disabling test mode\n");
490 			goto exit_dummy;
491 		}
492 	}
493 
494 	device_set_wakeup_capable(&client->dev, 1);
495 
496 	s35390a->rtc = devm_rtc_device_register(&client->dev,
497 					s35390a_driver.driver.name,
498 					&s35390a_rtc_ops, THIS_MODULE);
499 
500 	if (IS_ERR(s35390a->rtc)) {
501 		err = PTR_ERR(s35390a->rtc);
502 		goto exit_dummy;
503 	}
504 
505 	if (status1 & S35390A_FLAG_INT2)
506 		rtc_update_irq(s35390a->rtc, 1, RTC_AF);
507 
508 	return 0;
509 
510 exit_dummy:
511 	for (i = 1; i < 8; ++i)
512 		if (s35390a->client[i])
513 			i2c_unregister_device(s35390a->client[i]);
514 
515 exit:
516 	return err;
517 }
518 
s35390a_remove(struct i2c_client * client)519 static int s35390a_remove(struct i2c_client *client)
520 {
521 	unsigned int i;
522 	struct s35390a *s35390a = i2c_get_clientdata(client);
523 
524 	for (i = 1; i < 8; ++i)
525 		if (s35390a->client[i])
526 			i2c_unregister_device(s35390a->client[i]);
527 
528 	return 0;
529 }
530 
531 static struct i2c_driver s35390a_driver = {
532 	.driver		= {
533 		.name	= "rtc-s35390a",
534 		.of_match_table = of_match_ptr(s35390a_of_match),
535 	},
536 	.probe		= s35390a_probe,
537 	.remove		= s35390a_remove,
538 	.id_table	= s35390a_id,
539 };
540 
541 module_i2c_driver(s35390a_driver);
542 
543 MODULE_AUTHOR("Byron Bradley <byron.bbradley@gmail.com>");
544 MODULE_DESCRIPTION("S35390A RTC driver");
545 MODULE_LICENSE("GPL");
546