drivers/rtc/rtc-s35390a.c

   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         struct rtc_device *rtc;
  67         int twentyfourhour;
  68 };
  69
  70 static int s35390a_set_reg(struct s35390a *s35390a, int reg, char *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
  87 static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *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
 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  */
 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
 170 static int s35390a_disable_test_mode(struct s35390a *s35390a)
 171 {
 172         char 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
 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
 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
 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         char 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
 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         char 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
 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         char 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
 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         char 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
 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         char 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
 420 static int s35390a_probe(struct i2c_client *client)
 421 {
 422         int err, err_read;
 423         unsigned int i;
 424         struct s35390a *s35390a;
 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         s35390a->rtc = devm_rtc_allocate_device(dev);
 451         if (IS_ERR(s35390a->rtc))
 452                 return PTR_ERR(s35390a->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         s35390a->rtc->ops = &s35390a_rtc_ops;
 484         s35390a->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 485         s35390a->rtc->range_max = RTC_TIMESTAMP_END_2099;
 486
 487         set_bit(RTC_FEATURE_ALARM_RES_MINUTE, s35390a->rtc->features);
 488         clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, s35390a->rtc->features );
 489
 490         if (status1 & S35390A_FLAG_INT2)
 491                 rtc_update_irq(s35390a->rtc, 1, RTC_AF);
 492
 493         return devm_rtc_register_device(s35390a->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");