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        0x01
  36 #define S35390A_FLAG_BLD        0x02
  37 #define S35390A_FLAG_INT2       0x04
  38 #define S35390A_FLAG_24H        0x40
  39 #define S35390A_FLAG_RESET      0x80
  40
  41 /* flag for STATUS2 */
  42 #define S35390A_FLAG_TEST       0x01
  43
  44 #define S35390A_INT2_MODE_MASK          0xF0
  45
  46 #define S35390A_INT2_MODE_NOINTR        0x00
  47 #define S35390A_INT2_MODE_FREQ          0x10
  48 #define S35390A_INT2_MODE_ALARM         0x40
  49 #define S35390A_INT2_MODE_PMIN_EDG      0x20
  50
  51 static const struct i2c_device_id s35390a_id[] = {
  52         { "s35390a", 0 },
  53         { }
  54 };
  55 MODULE_DEVICE_TABLE(i2c, s35390a_id);
  56
  57 static const struct of_device_id s35390a_of_match[] = {
  58         { .compatible = "s35390a" },
  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, err;
 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         err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
 237
 238         return err;
 239 }
 240
 241 static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
 242 {
 243         struct i2c_client *client = to_i2c_client(dev);
 244         struct s35390a *s35390a = i2c_get_clientdata(client);
 245         char buf[7], status;
 246         int i, err;
 247
 248         if (s35390a_read_status(s35390a, &status) == 1)
 249                 return -EINVAL;
 250
 251         err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
 252         if (err < 0)
 253                 return err;
 254
 255         /* This chip returns the bits of each byte in reverse order */
 256         for (i = 0; i < 7; ++i)
 257                 buf[i] = bitrev8(buf[i]);
 258
 259         tm->tm_sec = bcd2bin(buf[S35390A_BYTE_SECS]);
 260         tm->tm_min = bcd2bin(buf[S35390A_BYTE_MINS]);
 261         tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
 262         tm->tm_wday = bcd2bin(buf[S35390A_BYTE_WDAY]);
 263         tm->tm_mday = bcd2bin(buf[S35390A_BYTE_DAY]);
 264         tm->tm_mon = bcd2bin(buf[S35390A_BYTE_MONTH]) - 1;
 265         tm->tm_year = bcd2bin(buf[S35390A_BYTE_YEAR]) + 100;
 266
 267         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, mday=%d, "
 268                 "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
 269                 tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
 270                 tm->tm_wday);
 271
 272         return 0;
 273 }
 274
 275 static int s35390a_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
 276 {
 277         struct i2c_client *client = to_i2c_client(dev);
 278         struct s35390a *s35390a = i2c_get_clientdata(client);
 279         char buf[3], sts = 0;
 280         int err, i;
 281
 282         dev_dbg(&client->dev, "%s: alm is secs=%d, mins=%d, hours=%d mday=%d, "\
 283                 "mon=%d, year=%d, wday=%d\n", __func__, alm->time.tm_sec,
 284                 alm->time.tm_min, alm->time.tm_hour, alm->time.tm_mday,
 285                 alm->time.tm_mon, alm->time.tm_year, alm->time.tm_wday);
 286
 287         /* disable interrupt (which deasserts the irq line) */
 288         err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
 289         if (err < 0)
 290                 return err;
 291
 292         /* clear pending interrupt (in STATUS1 only), if any */
 293         err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &sts, sizeof(sts));
 294         if (err < 0)
 295                 return err;
 296
 297         if (alm->enabled)
 298                 sts = S35390A_INT2_MODE_ALARM;
 299         else
 300                 sts = S35390A_INT2_MODE_NOINTR;
 301
 302         /* This chip expects the bits of each byte to be in reverse order */
 303         sts = bitrev8(sts);
 304
 305         /* set interupt mode*/
 306         err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
 307         if (err < 0)
 308                 return err;
 309
 310         if (alm->time.tm_wday != -1)
 311                 buf[S35390A_ALRM_BYTE_WDAY] = bin2bcd(alm->time.tm_wday) | 0x80;
 312         else
 313                 buf[S35390A_ALRM_BYTE_WDAY] = 0;
 314
 315         buf[S35390A_ALRM_BYTE_HOURS] = s35390a_hr2reg(s35390a,
 316                         alm->time.tm_hour) | 0x80;
 317         buf[S35390A_ALRM_BYTE_MINS] = bin2bcd(alm->time.tm_min) | 0x80;
 318
 319         if (alm->time.tm_hour >= 12)
 320                 buf[S35390A_ALRM_BYTE_HOURS] |= 0x40;
 321
 322         for (i = 0; i < 3; ++i)
 323                 buf[i] = bitrev8(buf[i]);
 324
 325         err = s35390a_set_reg(s35390a, S35390A_CMD_INT2_REG1, buf,
 326                                                                 sizeof(buf));
 327
 328         return err;
 329 }
 330
 331 static int s35390a_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
 332 {
 333         struct i2c_client *client = to_i2c_client(dev);
 334         struct s35390a *s35390a = i2c_get_clientdata(client);
 335         char buf[3], sts;
 336         int i, err;
 337
 338         err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
 339         if (err < 0)
 340                 return err;
 341
 342         if ((bitrev8(sts) & S35390A_INT2_MODE_MASK) != S35390A_INT2_MODE_ALARM) {
 343                 /*
 344                  * When the alarm isn't enabled, the register to configure
 345                  * the alarm time isn't accessible.
 346                  */
 347                 alm->enabled = 0;
 348                 return 0;
 349         } else {
 350                 alm->enabled = 1;
 351         }
 352
 353         err = s35390a_get_reg(s35390a, S35390A_CMD_INT2_REG1, buf, sizeof(buf));
 354         if (err < 0)
 355                 return err;
 356
 357         /* This chip returns the bits of each byte in reverse order */
 358         for (i = 0; i < 3; ++i)
 359                 buf[i] = bitrev8(buf[i]);
 360
 361         /*
 362          * B0 of the three matching registers is an enable flag. Iff it is set
 363          * the configured value is used for matching.
 364          */
 365         if (buf[S35390A_ALRM_BYTE_WDAY] & 0x80)
 366                 alm->time.tm_wday =
 367                         bcd2bin(buf[S35390A_ALRM_BYTE_WDAY] & ~0x80);
 368
 369         if (buf[S35390A_ALRM_BYTE_HOURS] & 0x80)
 370                 alm->time.tm_hour =
 371                         s35390a_reg2hr(s35390a,
 372                                        buf[S35390A_ALRM_BYTE_HOURS] & ~0x80);
 373
 374         if (buf[S35390A_ALRM_BYTE_MINS] & 0x80)
 375                 alm->time.tm_min = bcd2bin(buf[S35390A_ALRM_BYTE_MINS] & ~0x80);
 376
 377         /* alarm triggers always at s=0 */
 378         alm->time.tm_sec = 0;
 379
 380         dev_dbg(&client->dev, "%s: alm is mins=%d, hours=%d, wday=%d\n",
 381                         __func__, alm->time.tm_min, alm->time.tm_hour,
 382                         alm->time.tm_wday);
 383
 384         return 0;
 385 }
 386
 387 static int s35390a_rtc_ioctl(struct device *dev, unsigned int cmd,
 388                              unsigned long arg)
 389 {
 390         struct i2c_client *client = to_i2c_client(dev);
 391         struct s35390a *s35390a = i2c_get_clientdata(client);
 392         char sts;
 393         int err;
 394
 395         switch (cmd) {
 396         case RTC_VL_READ:
 397                 /* s35390a_reset set lowvoltage flag and init RTC if needed */
 398                 err = s35390a_read_status(s35390a, &sts);
 399                 if (err < 0)
 400                         return err;
 401                 if (copy_to_user((void __user *)arg, &err, sizeof(int)))
 402                         return -EFAULT;
 403                 break;
 404         case RTC_VL_CLR:
 405                 /* update flag and clear register */
 406                 err = s35390a_init(s35390a);
 407                 if (err < 0)
 408                         return err;
 409                 break;
 410         default:
 411                 return -ENOIOCTLCMD;
 412         }
 413
 414         return 0;
 415 }
 416
 417 static const struct rtc_class_ops s35390a_rtc_ops = {
 418         .read_time      = s35390a_rtc_read_time,
 419         .set_time       = s35390a_rtc_set_time,
 420         .set_alarm      = s35390a_rtc_set_alarm,
 421         .read_alarm     = s35390a_rtc_read_alarm,
 422         .ioctl          = s35390a_rtc_ioctl,
 423 };
 424
 425 static struct i2c_driver s35390a_driver;
 426
 427 static int s35390a_probe(struct i2c_client *client,
 428                          const struct i2c_device_id *id)
 429 {
 430         int err, err_read;
 431         unsigned int i;
 432         struct s35390a *s35390a;
 433         char buf, status1;
 434
 435         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
 436                 err = -ENODEV;
 437                 goto exit;
 438         }
 439
 440         s35390a = devm_kzalloc(&client->dev, sizeof(struct s35390a),
 441                                 GFP_KERNEL);
 442         if (!s35390a) {
 443                 err = -ENOMEM;
 444                 goto exit;
 445         }
 446
 447         s35390a->client[0] = client;
 448         i2c_set_clientdata(client, s35390a);
 449
 450         /* This chip uses multiple addresses, use dummy devices for them */
 451         for (i = 1; i < 8; ++i) {
 452                 s35390a->client[i] = i2c_new_dummy(client->adapter,
 453                                         client->addr + i);
 454                 if (!s35390a->client[i]) {
 455                         dev_err(&client->dev, "Address %02x unavailable\n",
 456                                                 client->addr + i);
 457                         err = -EBUSY;
 458                         goto exit_dummy;
 459                 }
 460         }
 461
 462         err_read = s35390a_read_status(s35390a, &status1);
 463         if (err_read < 0) {
 464                 err = err_read;
 465                 dev_err(&client->dev, "error resetting chip\n");
 466                 goto exit_dummy;
 467         }
 468
 469         if (status1 & S35390A_FLAG_24H)
 470                 s35390a->twentyfourhour = 1;
 471         else
 472                 s35390a->twentyfourhour = 0;
 473
 474         if (status1 & S35390A_FLAG_INT2) {
 475                 /* disable alarm (and maybe test mode) */
 476                 buf = 0;
 477                 err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &buf, 1);
 478                 if (err < 0) {
 479                         dev_err(&client->dev, "error disabling alarm");
 480                         goto exit_dummy;
 481                 }
 482         } else {
 483                 err = s35390a_disable_test_mode(s35390a);
 484                 if (err < 0) {
 485                         dev_err(&client->dev, "error disabling test mode\n");
 486                         goto exit_dummy;
 487                 }
 488         }
 489
 490         device_set_wakeup_capable(&client->dev, 1);
 491
 492         s35390a->rtc = devm_rtc_device_register(&client->dev,
 493                                         s35390a_driver.driver.name,
 494                                         &s35390a_rtc_ops, THIS_MODULE);
 495
 496         if (IS_ERR(s35390a->rtc)) {
 497                 err = PTR_ERR(s35390a->rtc);
 498                 goto exit_dummy;
 499         }
 500
 501         if (status1 & S35390A_FLAG_INT2)
 502                 rtc_update_irq(s35390a->rtc, 1, RTC_AF);
 503
 504         return 0;
 505
 506 exit_dummy:
 507         for (i = 1; i < 8; ++i)
 508                 if (s35390a->client[i])
 509                         i2c_unregister_device(s35390a->client[i]);
 510
 511 exit:
 512         return err;
 513 }
 514
 515 static int s35390a_remove(struct i2c_client *client)
 516 {
 517         unsigned int i;
 518         struct s35390a *s35390a = i2c_get_clientdata(client);
 519
 520         for (i = 1; i < 8; ++i)
 521                 if (s35390a->client[i])
 522                         i2c_unregister_device(s35390a->client[i]);
 523
 524         return 0;
 525 }
 526
 527 static struct i2c_driver s35390a_driver = {
 528         .driver         = {
 529                 .name   = "rtc-s35390a",
 530                 .of_match_table = of_match_ptr(s35390a_of_match),
 531         },
 532         .probe          = s35390a_probe,
 533         .remove         = s35390a_remove,
 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");