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 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 if (alm->time.tm_sec != 0)
289 dev_warn(&client->dev, "Alarms are only supported on a per minute basis!\n");
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 /* set interupt mode*/
307 err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
308 if (err < 0)
309 return err;
310
311 if (alm->time.tm_wday != -1)
312 buf[S35390A_ALRM_BYTE_WDAY] = bin2bcd(alm->time.tm_wday) | 0x80;
313 else
314 buf[S35390A_ALRM_BYTE_WDAY] = 0;
315
316 buf[S35390A_ALRM_BYTE_HOURS] = s35390a_hr2reg(s35390a,
317 alm->time.tm_hour) | 0x80;
318 buf[S35390A_ALRM_BYTE_MINS] = bin2bcd(alm->time.tm_min) | 0x80;
319
320 if (alm->time.tm_hour >= 12)
321 buf[S35390A_ALRM_BYTE_HOURS] |= 0x40;
322
323 for (i = 0; i < 3; ++i)
324 buf[i] = bitrev8(buf[i]);
325
326 err = s35390a_set_reg(s35390a, S35390A_CMD_INT2_REG1, buf,
327 sizeof(buf));
328
329 return err;
330 }
331
s35390a_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alm)332 static int s35390a_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
333 {
334 struct i2c_client *client = to_i2c_client(dev);
335 struct s35390a *s35390a = i2c_get_clientdata(client);
336 char buf[3], sts;
337 int i, err;
338
339 err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
340 if (err < 0)
341 return err;
342
343 if ((sts & S35390A_INT2_MODE_MASK) != S35390A_INT2_MODE_ALARM) {
344 /*
345 * When the alarm isn't enabled, the register to configure
346 * the alarm time isn't accessible.
347 */
348 alm->enabled = 0;
349 return 0;
350 } else {
351 alm->enabled = 1;
352 }
353
354 err = s35390a_get_reg(s35390a, S35390A_CMD_INT2_REG1, buf, sizeof(buf));
355 if (err < 0)
356 return err;
357
358 /* This chip returns the bits of each byte in reverse order */
359 for (i = 0; i < 3; ++i)
360 buf[i] = bitrev8(buf[i]);
361
362 /*
363 * B0 of the three matching registers is an enable flag. Iff it is set
364 * the configured value is used for matching.
365 */
366 if (buf[S35390A_ALRM_BYTE_WDAY] & 0x80)
367 alm->time.tm_wday =
368 bcd2bin(buf[S35390A_ALRM_BYTE_WDAY] & ~0x80);
369
370 if (buf[S35390A_ALRM_BYTE_HOURS] & 0x80)
371 alm->time.tm_hour =
372 s35390a_reg2hr(s35390a,
373 buf[S35390A_ALRM_BYTE_HOURS] & ~0x80);
374
375 if (buf[S35390A_ALRM_BYTE_MINS] & 0x80)
376 alm->time.tm_min = bcd2bin(buf[S35390A_ALRM_BYTE_MINS] & ~0x80);
377
378 /* alarm triggers always at s=0 */
379 alm->time.tm_sec = 0;
380
381 dev_dbg(&client->dev, "%s: alm is mins=%d, hours=%d, wday=%d\n",
382 __func__, alm->time.tm_min, alm->time.tm_hour,
383 alm->time.tm_wday);
384
385 return 0;
386 }
387
s35390a_rtc_ioctl(struct device * dev,unsigned int cmd,unsigned long arg)388 static int s35390a_rtc_ioctl(struct device *dev, unsigned int cmd,
389 unsigned long arg)
390 {
391 struct i2c_client *client = to_i2c_client(dev);
392 struct s35390a *s35390a = i2c_get_clientdata(client);
393 char sts;
394 int err;
395
396 switch (cmd) {
397 case RTC_VL_READ:
398 /* s35390a_reset set lowvoltage flag and init RTC if needed */
399 err = s35390a_read_status(s35390a, &sts);
400 if (err < 0)
401 return err;
402 if (copy_to_user((void __user *)arg, &err, sizeof(int)))
403 return -EFAULT;
404 break;
405 case RTC_VL_CLR:
406 /* update flag and clear register */
407 err = s35390a_init(s35390a);
408 if (err < 0)
409 return err;
410 break;
411 default:
412 return -ENOIOCTLCMD;
413 }
414
415 return 0;
416 }
417
418 static const struct rtc_class_ops s35390a_rtc_ops = {
419 .read_time = s35390a_rtc_read_time,
420 .set_time = s35390a_rtc_set_time,
421 .set_alarm = s35390a_rtc_set_alarm,
422 .read_alarm = s35390a_rtc_read_alarm,
423 .ioctl = s35390a_rtc_ioctl,
424 };
425
s35390a_probe(struct i2c_client * client,const struct i2c_device_id * id)426 static int s35390a_probe(struct i2c_client *client,
427 const struct i2c_device_id *id)
428 {
429 int err, err_read;
430 unsigned int i;
431 struct s35390a *s35390a;
432 char buf, status1;
433 struct device *dev = &client->dev;
434
435 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
436 return -ENODEV;
437
438 s35390a = devm_kzalloc(dev, sizeof(struct s35390a), GFP_KERNEL);
439 if (!s35390a)
440 return -ENOMEM;
441
442 s35390a->client[0] = client;
443 i2c_set_clientdata(client, s35390a);
444
445 /* This chip uses multiple addresses, use dummy devices for them */
446 for (i = 1; i < 8; ++i) {
447 s35390a->client[i] = devm_i2c_new_dummy_device(dev,
448 client->adapter,
449 client->addr + i);
450 if (IS_ERR(s35390a->client[i])) {
451 dev_err(dev, "Address %02x unavailable\n",
452 client->addr + i);
453 return PTR_ERR(s35390a->client[i]);
454 }
455 }
456
457 s35390a->rtc = devm_rtc_allocate_device(dev);
458 if (IS_ERR(s35390a->rtc))
459 return PTR_ERR(s35390a->rtc);
460
461 err_read = s35390a_read_status(s35390a, &status1);
462 if (err_read < 0) {
463 dev_err(dev, "error resetting chip\n");
464 return err_read;
465 }
466
467 if (status1 & S35390A_FLAG_24H)
468 s35390a->twentyfourhour = 1;
469 else
470 s35390a->twentyfourhour = 0;
471
472 if (status1 & S35390A_FLAG_INT2) {
473 /* disable alarm (and maybe test mode) */
474 buf = 0;
475 err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &buf, 1);
476 if (err < 0) {
477 dev_err(dev, "error disabling alarm");
478 return err;
479 }
480 } else {
481 err = s35390a_disable_test_mode(s35390a);
482 if (err < 0) {
483 dev_err(dev, "error disabling test mode\n");
484 return err;
485 }
486 }
487
488 device_set_wakeup_capable(dev, 1);
489
490 s35390a->rtc->ops = &s35390a_rtc_ops;
491 s35390a->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
492 s35390a->rtc->range_max = RTC_TIMESTAMP_END_2099;
493
494 /* supports per-minute alarms only, therefore set uie_unsupported */
495 s35390a->rtc->uie_unsupported = 1;
496
497 if (status1 & S35390A_FLAG_INT2)
498 rtc_update_irq(s35390a->rtc, 1, RTC_AF);
499
500 return rtc_register_device(s35390a->rtc);
501 }
502
503 static struct i2c_driver s35390a_driver = {
504 .driver = {
505 .name = "rtc-s35390a",
506 .of_match_table = of_match_ptr(s35390a_of_match),
507 },
508 .probe = s35390a_probe,
509 .id_table = s35390a_id,
510 };
511
512 module_i2c_driver(s35390a_driver);
513
514 MODULE_AUTHOR("Byron Bradley <byron.bbradley@gmail.com>");
515 MODULE_DESCRIPTION("S35390A RTC driver");
516 MODULE_LICENSE("GPL");
517