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", 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
  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
  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
 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  */
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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 devm_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");