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 #define S35390A_CMD_FREE_REG 7
22
23 #define S35390A_BYTE_YEAR 0
24 #define S35390A_BYTE_MONTH 1
25 #define S35390A_BYTE_DAY 2
26 #define S35390A_BYTE_WDAY 3
27 #define S35390A_BYTE_HOURS 4
28 #define S35390A_BYTE_MINS 5
29 #define S35390A_BYTE_SECS 6
30
31 #define S35390A_ALRM_BYTE_WDAY 0
32 #define S35390A_ALRM_BYTE_HOURS 1
33 #define S35390A_ALRM_BYTE_MINS 2
34
35 /* flags for STATUS1 */
36 #define S35390A_FLAG_POC BIT(0)
37 #define S35390A_FLAG_BLD BIT(1)
38 #define S35390A_FLAG_INT2 BIT(2)
39 #define S35390A_FLAG_24H BIT(6)
40 #define S35390A_FLAG_RESET BIT(7)
41
42 /* flag for STATUS2 */
43 #define S35390A_FLAG_TEST BIT(0)
44
45 /* INT2 pin output mode */
46 #define S35390A_INT2_MODE_MASK 0x0E
47 #define S35390A_INT2_MODE_NOINTR 0x00
48 #define S35390A_INT2_MODE_ALARM BIT(1) /* INT2AE */
49 #define S35390A_INT2_MODE_PMIN_EDG BIT(2) /* INT2ME */
50 #define S35390A_INT2_MODE_FREQ BIT(3) /* INT2FE */
51 #define S35390A_INT2_MODE_PMIN (BIT(3) | BIT(2)) /* INT2FE | INT2ME */
52
53 static const struct i2c_device_id s35390a_id[] = {
54 { "s35390a" },
55 { }
56 };
57 MODULE_DEVICE_TABLE(i2c, s35390a_id);
58
59 static const __maybe_unused struct of_device_id s35390a_of_match[] = {
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 int twentyfourhour;
68 };
69
s35390a_set_reg(struct s35390a * s35390a,int reg,u8 * buf,int len)70 static int s35390a_set_reg(struct s35390a *s35390a, int reg, u8 *buf, int len)
71 {
72 struct i2c_client *client = s35390a->client[reg];
73 struct i2c_msg msg[] = {
74 {
75 .addr = client->addr,
76 .len = len,
77 .buf = buf
78 },
79 };
80
81 if ((i2c_transfer(client->adapter, msg, 1)) != 1)
82 return -EIO;
83
84 return 0;
85 }
86
s35390a_get_reg(struct s35390a * s35390a,int reg,u8 * buf,int len)87 static int s35390a_get_reg(struct s35390a *s35390a, int reg, u8 *buf, int len)
88 {
89 struct i2c_client *client = s35390a->client[reg];
90 struct i2c_msg msg[] = {
91 {
92 .addr = client->addr,
93 .flags = I2C_M_RD,
94 .len = len,
95 .buf = buf
96 },
97 };
98
99 if ((i2c_transfer(client->adapter, msg, 1)) != 1)
100 return -EIO;
101
102 return 0;
103 }
104
s35390a_init(struct s35390a * s35390a)105 static int s35390a_init(struct s35390a *s35390a)
106 {
107 u8 buf;
108 int ret;
109 unsigned initcount = 0;
110
111 /*
112 * At least one of POC and BLD are set, so reinitialise chip. Keeping
113 * this information in the hardware to know later that the time isn't
114 * valid is unfortunately not possible because POC and BLD are cleared
115 * on read. So the reset is best done now.
116 *
117 * The 24H bit is kept over reset, so set it already here.
118 */
119 initialize:
120 buf = S35390A_FLAG_RESET | S35390A_FLAG_24H;
121 ret = s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
122
123 if (ret < 0)
124 return ret;
125
126 ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
127 if (ret < 0)
128 return ret;
129
130 if (buf & (S35390A_FLAG_POC | S35390A_FLAG_BLD)) {
131 /* Try up to five times to reset the chip */
132 if (initcount < 5) {
133 ++initcount;
134 goto initialize;
135 } else
136 return -EIO;
137 }
138
139 return 1;
140 }
141
142 /*
143 * Returns <0 on error, 0 if rtc is setup fine and 1 if the chip was reset.
144 * To keep the information if an irq is pending, pass the value read from
145 * STATUS1 to the caller.
146 */
s35390a_read_status(struct s35390a * s35390a,char * status1)147 static int s35390a_read_status(struct s35390a *s35390a, char *status1)
148 {
149 int ret;
150
151 ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, status1, 1);
152 if (ret < 0)
153 return ret;
154
155 if (*status1 & S35390A_FLAG_POC) {
156 /*
157 * Do not communicate for 0.5 seconds since the power-on
158 * detection circuit is in operation.
159 */
160 msleep(500);
161 return 1;
162 } else if (*status1 & S35390A_FLAG_BLD)
163 return 1;
164 /*
165 * If both POC and BLD are unset everything is fine.
166 */
167 return 0;
168 }
169
s35390a_disable_test_mode(struct s35390a * s35390a)170 static int s35390a_disable_test_mode(struct s35390a *s35390a)
171 {
172 u8 buf[1];
173
174 if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf)) < 0)
175 return -EIO;
176
177 if (!(buf[0] & S35390A_FLAG_TEST))
178 return 0;
179
180 buf[0] &= ~S35390A_FLAG_TEST;
181 return s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf));
182 }
183
s35390a_hr2reg(struct s35390a * s35390a,int hour)184 static char s35390a_hr2reg(struct s35390a *s35390a, int hour)
185 {
186 if (s35390a->twentyfourhour)
187 return bin2bcd(hour);
188
189 if (hour < 12)
190 return bin2bcd(hour);
191
192 return 0x40 | bin2bcd(hour - 12);
193 }
194
s35390a_reg2hr(struct s35390a * s35390a,char reg)195 static int s35390a_reg2hr(struct s35390a *s35390a, char reg)
196 {
197 unsigned hour;
198
199 if (s35390a->twentyfourhour)
200 return bcd2bin(reg & 0x3f);
201
202 hour = bcd2bin(reg & 0x3f);
203 if (reg & 0x40)
204 hour += 12;
205
206 return hour;
207 }
208
s35390a_rtc_set_time(struct device * dev,struct rtc_time * tm)209 static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
210 {
211 struct i2c_client *client = to_i2c_client(dev);
212 struct s35390a *s35390a = i2c_get_clientdata(client);
213 int i;
214 u8 buf[7], status;
215
216 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d mday=%d, "
217 "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
218 tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
219 tm->tm_wday);
220
221 if (s35390a_read_status(s35390a, &status) == 1)
222 s35390a_init(s35390a);
223
224 buf[S35390A_BYTE_YEAR] = bin2bcd(tm->tm_year - 100);
225 buf[S35390A_BYTE_MONTH] = bin2bcd(tm->tm_mon + 1);
226 buf[S35390A_BYTE_DAY] = bin2bcd(tm->tm_mday);
227 buf[S35390A_BYTE_WDAY] = bin2bcd(tm->tm_wday);
228 buf[S35390A_BYTE_HOURS] = s35390a_hr2reg(s35390a, tm->tm_hour);
229 buf[S35390A_BYTE_MINS] = bin2bcd(tm->tm_min);
230 buf[S35390A_BYTE_SECS] = bin2bcd(tm->tm_sec);
231
232 /* This chip expects the bits of each byte to be in reverse order */
233 for (i = 0; i < 7; ++i)
234 buf[i] = bitrev8(buf[i]);
235
236 return s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
237 }
238
s35390a_rtc_read_time(struct device * dev,struct rtc_time * tm)239 static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
240 {
241 struct i2c_client *client = to_i2c_client(dev);
242 struct s35390a *s35390a = i2c_get_clientdata(client);
243 u8 buf[7], status;
244 int i, err;
245
246 if (s35390a_read_status(s35390a, &status) == 1)
247 return -EINVAL;
248
249 err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
250 if (err < 0)
251 return err;
252
253 /* This chip returns the bits of each byte in reverse order */
254 for (i = 0; i < 7; ++i)
255 buf[i] = bitrev8(buf[i]);
256
257 tm->tm_sec = bcd2bin(buf[S35390A_BYTE_SECS]);
258 tm->tm_min = bcd2bin(buf[S35390A_BYTE_MINS]);
259 tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
260 tm->tm_wday = bcd2bin(buf[S35390A_BYTE_WDAY]);
261 tm->tm_mday = bcd2bin(buf[S35390A_BYTE_DAY]);
262 tm->tm_mon = bcd2bin(buf[S35390A_BYTE_MONTH]) - 1;
263 tm->tm_year = bcd2bin(buf[S35390A_BYTE_YEAR]) + 100;
264
265 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, mday=%d, "
266 "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
267 tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
268 tm->tm_wday);
269
270 return 0;
271 }
272
s35390a_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alm)273 static int s35390a_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
274 {
275 struct i2c_client *client = to_i2c_client(dev);
276 struct s35390a *s35390a = i2c_get_clientdata(client);
277 u8 buf[3], sts = 0;
278 int err, i;
279
280 dev_dbg(&client->dev, "%s: alm is secs=%d, mins=%d, hours=%d mday=%d, "\
281 "mon=%d, year=%d, wday=%d\n", __func__, alm->time.tm_sec,
282 alm->time.tm_min, alm->time.tm_hour, alm->time.tm_mday,
283 alm->time.tm_mon, alm->time.tm_year, alm->time.tm_wday);
284
285 /* disable interrupt (which deasserts the irq line) */
286 err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
287 if (err < 0)
288 return err;
289
290 /* clear pending interrupt (in STATUS1 only), if any */
291 err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &sts, sizeof(sts));
292 if (err < 0)
293 return err;
294
295 if (alm->enabled)
296 sts = S35390A_INT2_MODE_ALARM;
297 else
298 sts = S35390A_INT2_MODE_NOINTR;
299
300 /* set interupt mode*/
301 err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
302 if (err < 0)
303 return err;
304
305 if (alm->time.tm_wday != -1)
306 buf[S35390A_ALRM_BYTE_WDAY] = bin2bcd(alm->time.tm_wday) | 0x80;
307 else
308 buf[S35390A_ALRM_BYTE_WDAY] = 0;
309
310 buf[S35390A_ALRM_BYTE_HOURS] = s35390a_hr2reg(s35390a,
311 alm->time.tm_hour) | 0x80;
312 buf[S35390A_ALRM_BYTE_MINS] = bin2bcd(alm->time.tm_min) | 0x80;
313
314 if (alm->time.tm_hour >= 12)
315 buf[S35390A_ALRM_BYTE_HOURS] |= 0x40;
316
317 for (i = 0; i < 3; ++i)
318 buf[i] = bitrev8(buf[i]);
319
320 err = s35390a_set_reg(s35390a, S35390A_CMD_INT2_REG1, buf,
321 sizeof(buf));
322
323 return err;
324 }
325
s35390a_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alm)326 static int s35390a_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
327 {
328 struct i2c_client *client = to_i2c_client(dev);
329 struct s35390a *s35390a = i2c_get_clientdata(client);
330 u8 buf[3], sts;
331 int i, err;
332
333 err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
334 if (err < 0)
335 return err;
336
337 if ((sts & S35390A_INT2_MODE_MASK) != S35390A_INT2_MODE_ALARM) {
338 /*
339 * When the alarm isn't enabled, the register to configure
340 * the alarm time isn't accessible.
341 */
342 alm->enabled = 0;
343 return 0;
344 } else {
345 alm->enabled = 1;
346 }
347
348 err = s35390a_get_reg(s35390a, S35390A_CMD_INT2_REG1, buf, sizeof(buf));
349 if (err < 0)
350 return err;
351
352 /* This chip returns the bits of each byte in reverse order */
353 for (i = 0; i < 3; ++i)
354 buf[i] = bitrev8(buf[i]);
355
356 /*
357 * B0 of the three matching registers is an enable flag. Iff it is set
358 * the configured value is used for matching.
359 */
360 if (buf[S35390A_ALRM_BYTE_WDAY] & 0x80)
361 alm->time.tm_wday =
362 bcd2bin(buf[S35390A_ALRM_BYTE_WDAY] & ~0x80);
363
364 if (buf[S35390A_ALRM_BYTE_HOURS] & 0x80)
365 alm->time.tm_hour =
366 s35390a_reg2hr(s35390a,
367 buf[S35390A_ALRM_BYTE_HOURS] & ~0x80);
368
369 if (buf[S35390A_ALRM_BYTE_MINS] & 0x80)
370 alm->time.tm_min = bcd2bin(buf[S35390A_ALRM_BYTE_MINS] & ~0x80);
371
372 /* alarm triggers always at s=0 */
373 alm->time.tm_sec = 0;
374
375 dev_dbg(&client->dev, "%s: alm is mins=%d, hours=%d, wday=%d\n",
376 __func__, alm->time.tm_min, alm->time.tm_hour,
377 alm->time.tm_wday);
378
379 return 0;
380 }
381
s35390a_rtc_ioctl(struct device * dev,unsigned int cmd,unsigned long arg)382 static int s35390a_rtc_ioctl(struct device *dev, unsigned int cmd,
383 unsigned long arg)
384 {
385 struct i2c_client *client = to_i2c_client(dev);
386 struct s35390a *s35390a = i2c_get_clientdata(client);
387 u8 sts;
388 int err;
389
390 switch (cmd) {
391 case RTC_VL_READ:
392 /* s35390a_reset set lowvoltage flag and init RTC if needed */
393 err = s35390a_read_status(s35390a, &sts);
394 if (err < 0)
395 return err;
396 if (copy_to_user((void __user *)arg, &err, sizeof(int)))
397 return -EFAULT;
398 break;
399 case RTC_VL_CLR:
400 /* update flag and clear register */
401 err = s35390a_init(s35390a);
402 if (err < 0)
403 return err;
404 break;
405 default:
406 return -ENOIOCTLCMD;
407 }
408
409 return 0;
410 }
411
412 static const struct rtc_class_ops s35390a_rtc_ops = {
413 .read_time = s35390a_rtc_read_time,
414 .set_time = s35390a_rtc_set_time,
415 .set_alarm = s35390a_rtc_set_alarm,
416 .read_alarm = s35390a_rtc_read_alarm,
417 .ioctl = s35390a_rtc_ioctl,
418 };
419
s35390a_nvmem_read(void * priv,unsigned int offset,void * val,size_t bytes)420 static int s35390a_nvmem_read(void *priv, unsigned int offset, void *val,
421 size_t bytes)
422 {
423 struct s35390a *s35390a = priv;
424
425 /* The offset is ignored because the NVMEM region is only 1 byte */
426 return s35390a_get_reg(s35390a, S35390A_CMD_FREE_REG, val, bytes);
427 }
428
s35390a_nvmem_write(void * priv,unsigned int offset,void * val,size_t bytes)429 static int s35390a_nvmem_write(void *priv, unsigned int offset, void *val,
430 size_t bytes)
431 {
432 struct s35390a *s35390a = priv;
433
434 return s35390a_set_reg(s35390a, S35390A_CMD_FREE_REG, val, bytes);
435 }
436
s35390a_probe(struct i2c_client * client)437 static int s35390a_probe(struct i2c_client *client)
438 {
439 int err, err_read;
440 unsigned int i;
441 struct s35390a *s35390a;
442 struct rtc_device *rtc;
443 u8 buf, status1;
444 struct device *dev = &client->dev;
445 struct nvmem_config nvmem_cfg = {
446 .name = "s35390a_nvram",
447 .type = NVMEM_TYPE_BATTERY_BACKED,
448 .word_size = 1,
449 .stride = 1,
450 .size = 1,
451 .reg_read = s35390a_nvmem_read,
452 .reg_write = s35390a_nvmem_write,
453 };
454
455 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
456 return -ENODEV;
457
458 s35390a = devm_kzalloc(dev, sizeof(struct s35390a), GFP_KERNEL);
459 if (!s35390a)
460 return -ENOMEM;
461
462 s35390a->client[0] = client;
463 i2c_set_clientdata(client, s35390a);
464
465 /* This chip uses multiple addresses, use dummy devices for them */
466 for (i = 1; i < 8; ++i) {
467 s35390a->client[i] = devm_i2c_new_dummy_device(dev,
468 client->adapter,
469 client->addr + i);
470 if (IS_ERR(s35390a->client[i])) {
471 dev_err(dev, "Address %02x unavailable\n",
472 client->addr + i);
473 return PTR_ERR(s35390a->client[i]);
474 }
475 }
476
477 rtc = devm_rtc_allocate_device(dev);
478 if (IS_ERR(rtc))
479 return PTR_ERR(rtc);
480
481 err_read = s35390a_read_status(s35390a, &status1);
482 if (err_read < 0) {
483 dev_err(dev, "error resetting chip\n");
484 return err_read;
485 }
486
487 if (status1 & S35390A_FLAG_24H)
488 s35390a->twentyfourhour = 1;
489 else
490 s35390a->twentyfourhour = 0;
491
492 if (status1 & S35390A_FLAG_INT2) {
493 /* disable alarm (and maybe test mode) */
494 buf = 0;
495 err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &buf, 1);
496 if (err < 0) {
497 dev_err(dev, "error disabling alarm");
498 return err;
499 }
500 } else {
501 err = s35390a_disable_test_mode(s35390a);
502 if (err < 0) {
503 dev_err(dev, "error disabling test mode\n");
504 return err;
505 }
506 }
507
508 device_set_wakeup_capable(dev, 1);
509
510 rtc->ops = &s35390a_rtc_ops;
511 rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
512 rtc->range_max = RTC_TIMESTAMP_END_2099;
513
514 set_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->features);
515 clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);
516
517 if (status1 & S35390A_FLAG_INT2)
518 rtc_update_irq(rtc, 1, RTC_AF);
519
520 nvmem_cfg.priv = s35390a;
521 err = devm_rtc_nvmem_register(rtc, &nvmem_cfg);
522 if (err)
523 return err;
524
525 return devm_rtc_register_device(rtc);
526 }
527
528 static struct i2c_driver s35390a_driver = {
529 .driver = {
530 .name = "rtc-s35390a",
531 .of_match_table = of_match_ptr(s35390a_of_match),
532 },
533 .probe = s35390a_probe,
534 .id_table = s35390a_id,
535 };
536
537 module_i2c_driver(s35390a_driver);
538
539 MODULE_AUTHOR("Byron Bradley <byron.bbradley@gmail.com>");
540 MODULE_DESCRIPTION("S35390A RTC driver");
541 MODULE_LICENSE("GPL");
542