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