1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Seiko Instruments S-35390A RTC Driver
4  *
5  * Copyright (c) 2007 Byron Bradley
6  */
7 
8 #include <linux/module.h>
9 #include <linux/rtc.h>
10 #include <linux/i2c.h>
11 #include <linux/bitrev.h>
12 #include <linux/bcd.h>
13 #include <linux/slab.h>
14 #include <linux/delay.h>
15 
16 #define S35390A_CMD_STATUS1	0
17 #define S35390A_CMD_STATUS2	1
18 #define S35390A_CMD_TIME1	2
19 #define S35390A_CMD_TIME2	3
20 #define S35390A_CMD_INT2_REG1	5
21 
22 #define S35390A_BYTE_YEAR	0
23 #define S35390A_BYTE_MONTH	1
24 #define S35390A_BYTE_DAY	2
25 #define S35390A_BYTE_WDAY	3
26 #define S35390A_BYTE_HOURS	4
27 #define S35390A_BYTE_MINS	5
28 #define S35390A_BYTE_SECS	6
29 
30 #define S35390A_ALRM_BYTE_WDAY	0
31 #define S35390A_ALRM_BYTE_HOURS	1
32 #define S35390A_ALRM_BYTE_MINS	2
33 
34 /* flags for STATUS1 */
35 #define S35390A_FLAG_POC	BIT(0)
36 #define S35390A_FLAG_BLD	BIT(1)
37 #define S35390A_FLAG_INT2	BIT(2)
38 #define S35390A_FLAG_24H	BIT(6)
39 #define S35390A_FLAG_RESET	BIT(7)
40 
41 /* flag for STATUS2 */
42 #define S35390A_FLAG_TEST	BIT(0)
43 
44 /* INT2 pin output mode */
45 #define S35390A_INT2_MODE_MASK		0x0E
46 #define S35390A_INT2_MODE_NOINTR	0x00
47 #define S35390A_INT2_MODE_ALARM		BIT(1) /* INT2AE */
48 #define S35390A_INT2_MODE_PMIN_EDG	BIT(2) /* INT2ME */
49 #define S35390A_INT2_MODE_FREQ		BIT(3) /* INT2FE */
50 #define S35390A_INT2_MODE_PMIN		(BIT(3) | BIT(2)) /* INT2FE | INT2ME */
51 
52 static const struct i2c_device_id s35390a_id[] = {
53 	{ "s35390a", 0 },
54 	{ }
55 };
56 MODULE_DEVICE_TABLE(i2c, s35390a_id);
57 
58 static const __maybe_unused struct of_device_id s35390a_of_match[] = {
59 	{ .compatible = "s35390a" },
60 	{ .compatible = "sii,s35390a" },
61 	{ }
62 };
63 MODULE_DEVICE_TABLE(of, s35390a_of_match);
64 
65 struct s35390a {
66 	struct i2c_client *client[8];
67 	struct rtc_device *rtc;
68 	int twentyfourhour;
69 };
70 
s35390a_set_reg(struct s35390a * s35390a,int reg,char * buf,int len)71 static int s35390a_set_reg(struct s35390a *s35390a, int reg, char *buf, int len)
72 {
73 	struct i2c_client *client = s35390a->client[reg];
74 	struct i2c_msg msg[] = {
75 		{
76 			.addr = client->addr,
77 			.len = len,
78 			.buf = buf
79 		},
80 	};
81 
82 	if ((i2c_transfer(client->adapter, msg, 1)) != 1)
83 		return -EIO;
84 
85 	return 0;
86 }
87 
s35390a_get_reg(struct s35390a * s35390a,int reg,char * buf,int len)88 static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *buf, int len)
89 {
90 	struct i2c_client *client = s35390a->client[reg];
91 	struct i2c_msg msg[] = {
92 		{
93 			.addr = client->addr,
94 			.flags = I2C_M_RD,
95 			.len = len,
96 			.buf = buf
97 		},
98 	};
99 
100 	if ((i2c_transfer(client->adapter, msg, 1)) != 1)
101 		return -EIO;
102 
103 	return 0;
104 }
105 
s35390a_init(struct s35390a * s35390a)106 static int s35390a_init(struct s35390a *s35390a)
107 {
108 	u8 buf;
109 	int ret;
110 	unsigned initcount = 0;
111 
112 	/*
113 	 * At least one of POC and BLD are set, so reinitialise chip. Keeping
114 	 * this information in the hardware to know later that the time isn't
115 	 * valid is unfortunately not possible because POC and BLD are cleared
116 	 * on read. So the reset is best done now.
117 	 *
118 	 * The 24H bit is kept over reset, so set it already here.
119 	 */
120 initialize:
121 	buf = S35390A_FLAG_RESET | S35390A_FLAG_24H;
122 	ret = s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
123 
124 	if (ret < 0)
125 		return ret;
126 
127 	ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
128 	if (ret < 0)
129 		return ret;
130 
131 	if (buf & (S35390A_FLAG_POC | S35390A_FLAG_BLD)) {
132 		/* Try up to five times to reset the chip */
133 		if (initcount < 5) {
134 			++initcount;
135 			goto initialize;
136 		} else
137 			return -EIO;
138 	}
139 
140 	return 1;
141 }
142 
143 /*
144  * Returns <0 on error, 0 if rtc is setup fine and 1 if the chip was reset.
145  * To keep the information if an irq is pending, pass the value read from
146  * STATUS1 to the caller.
147  */
s35390a_read_status(struct s35390a * s35390a,char * status1)148 static int s35390a_read_status(struct s35390a *s35390a, char *status1)
149 {
150 	int ret;
151 
152 	ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, status1, 1);
153 	if (ret < 0)
154 		return ret;
155 
156 	if (*status1 & S35390A_FLAG_POC) {
157 		/*
158 		 * Do not communicate for 0.5 seconds since the power-on
159 		 * detection circuit is in operation.
160 		 */
161 		msleep(500);
162 		return 1;
163 	} else if (*status1 & S35390A_FLAG_BLD)
164 		return 1;
165 	/*
166 	 * If both POC and BLD are unset everything is fine.
167 	 */
168 	return 0;
169 }
170 
s35390a_disable_test_mode(struct s35390a * s35390a)171 static int s35390a_disable_test_mode(struct s35390a *s35390a)
172 {
173 	char buf[1];
174 
175 	if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf)) < 0)
176 		return -EIO;
177 
178 	if (!(buf[0] & S35390A_FLAG_TEST))
179 		return 0;
180 
181 	buf[0] &= ~S35390A_FLAG_TEST;
182 	return s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf));
183 }
184 
s35390a_hr2reg(struct s35390a * s35390a,int hour)185 static char s35390a_hr2reg(struct s35390a *s35390a, int hour)
186 {
187 	if (s35390a->twentyfourhour)
188 		return bin2bcd(hour);
189 
190 	if (hour < 12)
191 		return bin2bcd(hour);
192 
193 	return 0x40 | bin2bcd(hour - 12);
194 }
195 
s35390a_reg2hr(struct s35390a * s35390a,char reg)196 static int s35390a_reg2hr(struct s35390a *s35390a, char reg)
197 {
198 	unsigned hour;
199 
200 	if (s35390a->twentyfourhour)
201 		return bcd2bin(reg & 0x3f);
202 
203 	hour = bcd2bin(reg & 0x3f);
204 	if (reg & 0x40)
205 		hour += 12;
206 
207 	return hour;
208 }
209 
s35390a_rtc_set_time(struct device * dev,struct rtc_time * tm)210 static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
211 {
212 	struct i2c_client *client = to_i2c_client(dev);
213 	struct s35390a	*s35390a = i2c_get_clientdata(client);
214 	int i, err;
215 	char buf[7], status;
216 
217 	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d mday=%d, "
218 		"mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
219 		tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
220 		tm->tm_wday);
221 
222 	if (s35390a_read_status(s35390a, &status) == 1)
223 		s35390a_init(s35390a);
224 
225 	buf[S35390A_BYTE_YEAR] = bin2bcd(tm->tm_year - 100);
226 	buf[S35390A_BYTE_MONTH] = bin2bcd(tm->tm_mon + 1);
227 	buf[S35390A_BYTE_DAY] = bin2bcd(tm->tm_mday);
228 	buf[S35390A_BYTE_WDAY] = bin2bcd(tm->tm_wday);
229 	buf[S35390A_BYTE_HOURS] = s35390a_hr2reg(s35390a, tm->tm_hour);
230 	buf[S35390A_BYTE_MINS] = bin2bcd(tm->tm_min);
231 	buf[S35390A_BYTE_SECS] = bin2bcd(tm->tm_sec);
232 
233 	/* This chip expects the bits of each byte to be in reverse order */
234 	for (i = 0; i < 7; ++i)
235 		buf[i] = bitrev8(buf[i]);
236 
237 	err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
238 
239 	return err;
240 }
241 
s35390a_rtc_read_time(struct device * dev,struct rtc_time * tm)242 static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
243 {
244 	struct i2c_client *client = to_i2c_client(dev);
245 	struct s35390a *s35390a = i2c_get_clientdata(client);
246 	char buf[7], status;
247 	int i, err;
248 
249 	if (s35390a_read_status(s35390a, &status) == 1)
250 		return -EINVAL;
251 
252 	err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
253 	if (err < 0)
254 		return err;
255 
256 	/* This chip returns the bits of each byte in reverse order */
257 	for (i = 0; i < 7; ++i)
258 		buf[i] = bitrev8(buf[i]);
259 
260 	tm->tm_sec = bcd2bin(buf[S35390A_BYTE_SECS]);
261 	tm->tm_min = bcd2bin(buf[S35390A_BYTE_MINS]);
262 	tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
263 	tm->tm_wday = bcd2bin(buf[S35390A_BYTE_WDAY]);
264 	tm->tm_mday = bcd2bin(buf[S35390A_BYTE_DAY]);
265 	tm->tm_mon = bcd2bin(buf[S35390A_BYTE_MONTH]) - 1;
266 	tm->tm_year = bcd2bin(buf[S35390A_BYTE_YEAR]) + 100;
267 
268 	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, mday=%d, "
269 		"mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
270 		tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
271 		tm->tm_wday);
272 
273 	return 0;
274 }
275 
s35390a_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alm)276 static int s35390a_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
277 {
278 	struct i2c_client *client = to_i2c_client(dev);
279 	struct s35390a *s35390a = i2c_get_clientdata(client);
280 	char buf[3], sts = 0;
281 	int err, i;
282 
283 	dev_dbg(&client->dev, "%s: alm is secs=%d, mins=%d, hours=%d mday=%d, "\
284 		"mon=%d, year=%d, wday=%d\n", __func__, alm->time.tm_sec,
285 		alm->time.tm_min, alm->time.tm_hour, alm->time.tm_mday,
286 		alm->time.tm_mon, alm->time.tm_year, alm->time.tm_wday);
287 
288 	/* disable interrupt (which deasserts the irq line) */
289 	err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
290 	if (err < 0)
291 		return err;
292 
293 	/* clear pending interrupt (in STATUS1 only), if any */
294 	err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &sts, sizeof(sts));
295 	if (err < 0)
296 		return err;
297 
298 	if (alm->enabled)
299 		sts = S35390A_INT2_MODE_ALARM;
300 	else
301 		sts = S35390A_INT2_MODE_NOINTR;
302 
303 	/* set interupt mode*/
304 	err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
305 	if (err < 0)
306 		return err;
307 
308 	if (alm->time.tm_wday != -1)
309 		buf[S35390A_ALRM_BYTE_WDAY] = bin2bcd(alm->time.tm_wday) | 0x80;
310 	else
311 		buf[S35390A_ALRM_BYTE_WDAY] = 0;
312 
313 	buf[S35390A_ALRM_BYTE_HOURS] = s35390a_hr2reg(s35390a,
314 			alm->time.tm_hour) | 0x80;
315 	buf[S35390A_ALRM_BYTE_MINS] = bin2bcd(alm->time.tm_min) | 0x80;
316 
317 	if (alm->time.tm_hour >= 12)
318 		buf[S35390A_ALRM_BYTE_HOURS] |= 0x40;
319 
320 	for (i = 0; i < 3; ++i)
321 		buf[i] = bitrev8(buf[i]);
322 
323 	err = s35390a_set_reg(s35390a, S35390A_CMD_INT2_REG1, buf,
324 								sizeof(buf));
325 
326 	return err;
327 }
328 
s35390a_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alm)329 static int s35390a_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
330 {
331 	struct i2c_client *client = to_i2c_client(dev);
332 	struct s35390a *s35390a = i2c_get_clientdata(client);
333 	char buf[3], sts;
334 	int i, err;
335 
336 	err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
337 	if (err < 0)
338 		return err;
339 
340 	if ((sts & S35390A_INT2_MODE_MASK) != S35390A_INT2_MODE_ALARM) {
341 		/*
342 		 * When the alarm isn't enabled, the register to configure
343 		 * the alarm time isn't accessible.
344 		 */
345 		alm->enabled = 0;
346 		return 0;
347 	} else {
348 		alm->enabled = 1;
349 	}
350 
351 	err = s35390a_get_reg(s35390a, S35390A_CMD_INT2_REG1, buf, sizeof(buf));
352 	if (err < 0)
353 		return err;
354 
355 	/* This chip returns the bits of each byte in reverse order */
356 	for (i = 0; i < 3; ++i)
357 		buf[i] = bitrev8(buf[i]);
358 
359 	/*
360 	 * B0 of the three matching registers is an enable flag. Iff it is set
361 	 * the configured value is used for matching.
362 	 */
363 	if (buf[S35390A_ALRM_BYTE_WDAY] & 0x80)
364 		alm->time.tm_wday =
365 			bcd2bin(buf[S35390A_ALRM_BYTE_WDAY] & ~0x80);
366 
367 	if (buf[S35390A_ALRM_BYTE_HOURS] & 0x80)
368 		alm->time.tm_hour =
369 			s35390a_reg2hr(s35390a,
370 				       buf[S35390A_ALRM_BYTE_HOURS] & ~0x80);
371 
372 	if (buf[S35390A_ALRM_BYTE_MINS] & 0x80)
373 		alm->time.tm_min = bcd2bin(buf[S35390A_ALRM_BYTE_MINS] & ~0x80);
374 
375 	/* alarm triggers always at s=0 */
376 	alm->time.tm_sec = 0;
377 
378 	dev_dbg(&client->dev, "%s: alm is mins=%d, hours=%d, wday=%d\n",
379 			__func__, alm->time.tm_min, alm->time.tm_hour,
380 			alm->time.tm_wday);
381 
382 	return 0;
383 }
384 
s35390a_rtc_ioctl(struct device * dev,unsigned int cmd,unsigned long arg)385 static int s35390a_rtc_ioctl(struct device *dev, unsigned int cmd,
386 			     unsigned long arg)
387 {
388 	struct i2c_client *client = to_i2c_client(dev);
389 	struct s35390a *s35390a = i2c_get_clientdata(client);
390 	char sts;
391 	int err;
392 
393 	switch (cmd) {
394 	case RTC_VL_READ:
395 		/* s35390a_reset set lowvoltage flag and init RTC if needed */
396 		err = s35390a_read_status(s35390a, &sts);
397 		if (err < 0)
398 			return err;
399 		if (copy_to_user((void __user *)arg, &err, sizeof(int)))
400 			return -EFAULT;
401 		break;
402 	case RTC_VL_CLR:
403 		/* update flag and clear register */
404 		err = s35390a_init(s35390a);
405 		if (err < 0)
406 			return err;
407 		break;
408 	default:
409 		return -ENOIOCTLCMD;
410 	}
411 
412 	return 0;
413 }
414 
415 static const struct rtc_class_ops s35390a_rtc_ops = {
416 	.read_time	= s35390a_rtc_read_time,
417 	.set_time	= s35390a_rtc_set_time,
418 	.set_alarm	= s35390a_rtc_set_alarm,
419 	.read_alarm	= s35390a_rtc_read_alarm,
420 	.ioctl          = s35390a_rtc_ioctl,
421 };
422 
s35390a_probe(struct i2c_client * client,const struct i2c_device_id * id)423 static int s35390a_probe(struct i2c_client *client,
424 			 const struct i2c_device_id *id)
425 {
426 	int err, err_read;
427 	unsigned int i;
428 	struct s35390a *s35390a;
429 	char buf, status1;
430 	struct device *dev = &client->dev;
431 
432 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
433 		return -ENODEV;
434 
435 	s35390a = devm_kzalloc(dev, sizeof(struct s35390a), GFP_KERNEL);
436 	if (!s35390a)
437 		return -ENOMEM;
438 
439 	s35390a->client[0] = client;
440 	i2c_set_clientdata(client, s35390a);
441 
442 	/* This chip uses multiple addresses, use dummy devices for them */
443 	for (i = 1; i < 8; ++i) {
444 		s35390a->client[i] = devm_i2c_new_dummy_device(dev,
445 							       client->adapter,
446 							       client->addr + i);
447 		if (IS_ERR(s35390a->client[i])) {
448 			dev_err(dev, "Address %02x unavailable\n",
449 				client->addr + i);
450 			return PTR_ERR(s35390a->client[i]);
451 		}
452 	}
453 
454 	s35390a->rtc = devm_rtc_allocate_device(dev);
455 	if (IS_ERR(s35390a->rtc))
456 		return PTR_ERR(s35390a->rtc);
457 
458 	err_read = s35390a_read_status(s35390a, &status1);
459 	if (err_read < 0) {
460 		dev_err(dev, "error resetting chip\n");
461 		return err_read;
462 	}
463 
464 	if (status1 & S35390A_FLAG_24H)
465 		s35390a->twentyfourhour = 1;
466 	else
467 		s35390a->twentyfourhour = 0;
468 
469 	if (status1 & S35390A_FLAG_INT2) {
470 		/* disable alarm (and maybe test mode) */
471 		buf = 0;
472 		err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &buf, 1);
473 		if (err < 0) {
474 			dev_err(dev, "error disabling alarm");
475 			return err;
476 		}
477 	} else {
478 		err = s35390a_disable_test_mode(s35390a);
479 		if (err < 0) {
480 			dev_err(dev, "error disabling test mode\n");
481 			return err;
482 		}
483 	}
484 
485 	device_set_wakeup_capable(dev, 1);
486 
487 	s35390a->rtc->ops = &s35390a_rtc_ops;
488 	s35390a->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
489 	s35390a->rtc->range_max = RTC_TIMESTAMP_END_2099;
490 
491 	set_bit(RTC_FEATURE_ALARM_RES_MINUTE, s35390a->rtc->features);
492 	clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, s35390a->rtc->features );
493 
494 	if (status1 & S35390A_FLAG_INT2)
495 		rtc_update_irq(s35390a->rtc, 1, RTC_AF);
496 
497 	return devm_rtc_register_device(s35390a->rtc);
498 }
499 
500 static struct i2c_driver s35390a_driver = {
501 	.driver		= {
502 		.name	= "rtc-s35390a",
503 		.of_match_table = of_match_ptr(s35390a_of_match),
504 	},
505 	.probe		= s35390a_probe,
506 	.id_table	= s35390a_id,
507 };
508 
509 module_i2c_driver(s35390a_driver);
510 
511 MODULE_AUTHOR("Byron Bradley <byron.bbradley@gmail.com>");
512 MODULE_DESCRIPTION("S35390A RTC driver");
513 MODULE_LICENSE("GPL");
514