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