drivers/rtc/rtc-s35390a.c

   1 /*
   2  * Seiko Instruments S-35390A RTC Driver
   3  *
   4  * Copyright (c) 2007 Byron Bradley
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/rtc.h>
  14 #include <linux/i2c.h>
  15 #include <linux/bitrev.h>
  16 #include <linux/bcd.h>
  17 #include <linux/slab.h>
  18 #include <linux/delay.h>
  19
  20 #define S35390A_CMD_STATUS1     0
  21 #define S35390A_CMD_STATUS2     1
  22 #define S35390A_CMD_TIME1       2
  23 #define S35390A_CMD_TIME2       3
  24 #define S35390A_CMD_INT2_REG1   5
  25
  26 #define S35390A_BYTE_YEAR       0
  27 #define S35390A_BYTE_MONTH      1
  28 #define S35390A_BYTE_DAY        2
  29 #define S35390A_BYTE_WDAY       3
  30 #define S35390A_BYTE_HOURS      4
  31 #define S35390A_BYTE_MINS       5
  32 #define S35390A_BYTE_SECS       6
  33
  34 #define S35390A_ALRM_BYTE_WDAY  0
  35 #define S35390A_ALRM_BYTE_HOURS 1
  36 #define S35390A_ALRM_BYTE_MINS  2
  37
  38 /* flags for STATUS1 */
  39 #define S35390A_FLAG_POC        0x01
  40 #define S35390A_FLAG_BLD        0x02
  41 #define S35390A_FLAG_INT2       0x04
  42 #define S35390A_FLAG_24H        0x40
  43 #define S35390A_FLAG_RESET      0x80
  44
  45 /* flag for STATUS2 */
  46 #define S35390A_FLAG_TEST       0x01
  47
  48 #define S35390A_INT2_MODE_MASK          0xF0
  49
  50 #define S35390A_INT2_MODE_NOINTR        0x00
  51 #define S35390A_INT2_MODE_FREQ          0x10
  52 #define S35390A_INT2_MODE_ALARM         0x40
  53 #define S35390A_INT2_MODE_PMIN_EDG      0x20
  54
  55 static const struct i2c_device_id s35390a_id[] = {
  56         { "s35390a", 0 },
  57         { }
  58 };
  59 MODULE_DEVICE_TABLE(i2c, s35390a_id);
  60
  61 struct s35390a {
  62         struct i2c_client *client[8];
  63         struct rtc_device *rtc;
  64         int twentyfourhour;
  65 };
  66
  67 static int s35390a_set_reg(struct s35390a *s35390a, int reg, char *buf, int len)
  68 {
  69         struct i2c_client *client = s35390a->client[reg];
  70         struct i2c_msg msg[] = {
  71                 {
  72                         .addr = client->addr,
  73                         .len = len,
  74                         .buf = buf
  75                 },
  76         };
  77
  78         if ((i2c_transfer(client->adapter, msg, 1)) != 1)
  79                 return -EIO;
  80
  81         return 0;
  82 }
  83
  84 static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *buf, int len)
  85 {
  86         struct i2c_client *client = s35390a->client[reg];
  87         struct i2c_msg msg[] = {
  88                 {
  89                         .addr = client->addr,
  90                         .flags = I2C_M_RD,
  91                         .len = len,
  92                         .buf = buf
  93                 },
  94         };
  95
  96         if ((i2c_transfer(client->adapter, msg, 1)) != 1)
  97                 return -EIO;
  98
  99         return 0;
 100 }
 101
 102 /*
 103  * Returns <0 on error, 0 if rtc is setup fine and 1 if the chip was reset.
 104  * To keep the information if an irq is pending, pass the value read from
 105  * STATUS1 to the caller.
 106  */
 107 static int s35390a_reset(struct s35390a *s35390a, char *status1)
 108 {
 109         char buf;
 110         int ret;
 111         unsigned initcount = 0;
 112
 113         ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, status1, 1);
 114         if (ret < 0)
 115                 return ret;
 116
 117         if (*status1 & S35390A_FLAG_POC)
 118                 /*
 119                  * Do not communicate for 0.5 seconds since the power-on
 120                  * detection circuit is in operation.
 121                  */
 122                 msleep(500);
 123         else if (!(*status1 & S35390A_FLAG_BLD))
 124                 /*
 125                  * If both POC and BLD are unset everything is fine.
 126                  */
 127                 return 0;
 128
 129         /*
 130          * At least one of POC and BLD are set, so reinitialise chip. Keeping
 131          * this information in the hardware to know later that the time isn't
 132          * valid is unfortunately not possible because POC and BLD are cleared
 133          * on read. So the reset is best done now.
 134          *
 135          * The 24H bit is kept over reset, so set it already here.
 136          */
 137 initialize:
 138         *status1 = S35390A_FLAG_24H;
 139         buf = S35390A_FLAG_RESET | S35390A_FLAG_24H;
 140         ret = s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
 141
 142         if (ret < 0)
 143                 return ret;
 144
 145         ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
 146         if (ret < 0)
 147                 return ret;
 148
 149         if (buf & (S35390A_FLAG_POC | S35390A_FLAG_BLD)) {
 150                 /* Try up to five times to reset the chip */
 151                 if (initcount < 5) {
 152                         ++initcount;
 153                         goto initialize;
 154                 } else
 155                         return -EIO;
 156         }
 157
 158         return 1;
 159 }
 160
 161 static int s35390a_disable_test_mode(struct s35390a *s35390a)
 162 {
 163         char buf[1];
 164
 165         if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf)) < 0)
 166                 return -EIO;
 167
 168         if (!(buf[0] & S35390A_FLAG_TEST))
 169                 return 0;
 170
 171         buf[0] &= ~S35390A_FLAG_TEST;
 172         return s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf));
 173 }
 174
 175 static char s35390a_hr2reg(struct s35390a *s35390a, int hour)
 176 {
 177         if (s35390a->twentyfourhour)
 178                 return bin2bcd(hour);
 179
 180         if (hour < 12)
 181                 return bin2bcd(hour);
 182
 183         return 0x40 | bin2bcd(hour - 12);
 184 }
 185
 186 static int s35390a_reg2hr(struct s35390a *s35390a, char reg)
 187 {
 188         unsigned hour;
 189
 190         if (s35390a->twentyfourhour)
 191                 return bcd2bin(reg & 0x3f);
 192
 193         hour = bcd2bin(reg & 0x3f);
 194         if (reg & 0x40)
 195                 hour += 12;
 196
 197         return hour;
 198 }
 199
 200 static int s35390a_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 201 {
 202         struct s35390a  *s35390a = i2c_get_clientdata(client);
 203         int i, err;
 204         char buf[7];
 205
 206         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d mday=%d, "
 207                 "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
 208                 tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
 209                 tm->tm_wday);
 210
 211         buf[S35390A_BYTE_YEAR] = bin2bcd(tm->tm_year - 100);
 212         buf[S35390A_BYTE_MONTH] = bin2bcd(tm->tm_mon + 1);
 213         buf[S35390A_BYTE_DAY] = bin2bcd(tm->tm_mday);
 214         buf[S35390A_BYTE_WDAY] = bin2bcd(tm->tm_wday);
 215         buf[S35390A_BYTE_HOURS] = s35390a_hr2reg(s35390a, tm->tm_hour);
 216         buf[S35390A_BYTE_MINS] = bin2bcd(tm->tm_min);
 217         buf[S35390A_BYTE_SECS] = bin2bcd(tm->tm_sec);
 218
 219         /* This chip expects the bits of each byte to be in reverse order */
 220         for (i = 0; i < 7; ++i)
 221                 buf[i] = bitrev8(buf[i]);
 222
 223         err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
 224
 225         return err;
 226 }
 227
 228 static int s35390a_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 229 {
 230         struct s35390a *s35390a = i2c_get_clientdata(client);
 231         char buf[7];
 232         int i, err;
 233
 234         err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
 235         if (err < 0)
 236                 return err;
 237
 238         /* This chip returns the bits of each byte in reverse order */
 239         for (i = 0; i < 7; ++i)
 240                 buf[i] = bitrev8(buf[i]);
 241
 242         tm->tm_sec = bcd2bin(buf[S35390A_BYTE_SECS]);
 243         tm->tm_min = bcd2bin(buf[S35390A_BYTE_MINS]);
 244         tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
 245         tm->tm_wday = bcd2bin(buf[S35390A_BYTE_WDAY]);
 246         tm->tm_mday = bcd2bin(buf[S35390A_BYTE_DAY]);
 247         tm->tm_mon = bcd2bin(buf[S35390A_BYTE_MONTH]) - 1;
 248         tm->tm_year = bcd2bin(buf[S35390A_BYTE_YEAR]) + 100;
 249
 250         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, mday=%d, "
 251                 "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
 252                 tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
 253                 tm->tm_wday);
 254
 255         return rtc_valid_tm(tm);
 256 }
 257
 258 static int s35390a_set_alarm(struct i2c_client *client, struct rtc_wkalrm *alm)
 259 {
 260         struct s35390a *s35390a = i2c_get_clientdata(client);
 261         char buf[3], sts = 0;
 262         int err, i;
 263
 264         dev_dbg(&client->dev, "%s: alm is secs=%d, mins=%d, hours=%d mday=%d, "\
 265                 "mon=%d, year=%d, wday=%d\n", __func__, alm->time.tm_sec,
 266                 alm->time.tm_min, alm->time.tm_hour, alm->time.tm_mday,
 267                 alm->time.tm_mon, alm->time.tm_year, alm->time.tm_wday);
 268
 269         /* disable interrupt (which deasserts the irq line) */
 270         err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
 271         if (err < 0)
 272                 return err;
 273
 274         /* clear pending interrupt (in STATUS1 only), if any */
 275         err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &sts, sizeof(sts));
 276         if (err < 0)
 277                 return err;
 278
 279         if (alm->enabled)
 280                 sts = S35390A_INT2_MODE_ALARM;
 281         else
 282                 sts = S35390A_INT2_MODE_NOINTR;
 283
 284         /* This chip expects the bits of each byte to be in reverse order */
 285         sts = bitrev8(sts);
 286
 287         /* set interupt mode*/
 288         err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
 289         if (err < 0)
 290                 return err;
 291
 292         if (alm->time.tm_wday != -1)
 293                 buf[S35390A_ALRM_BYTE_WDAY] = bin2bcd(alm->time.tm_wday) | 0x80;
 294         else
 295                 buf[S35390A_ALRM_BYTE_WDAY] = 0;
 296
 297         buf[S35390A_ALRM_BYTE_HOURS] = s35390a_hr2reg(s35390a,
 298                         alm->time.tm_hour) | 0x80;
 299         buf[S35390A_ALRM_BYTE_MINS] = bin2bcd(alm->time.tm_min) | 0x80;
 300
 301         if (alm->time.tm_hour >= 12)
 302                 buf[S35390A_ALRM_BYTE_HOURS] |= 0x40;
 303
 304         for (i = 0; i < 3; ++i)
 305                 buf[i] = bitrev8(buf[i]);
 306
 307         err = s35390a_set_reg(s35390a, S35390A_CMD_INT2_REG1, buf,
 308                                                                 sizeof(buf));
 309
 310         return err;
 311 }
 312
 313 static int s35390a_read_alarm(struct i2c_client *client, struct rtc_wkalrm *alm)
 314 {
 315         struct s35390a *s35390a = i2c_get_clientdata(client);
 316         char buf[3], sts;
 317         int i, err;
 318
 319         err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
 320         if (err < 0)
 321                 return err;
 322
 323         if ((bitrev8(sts) & S35390A_INT2_MODE_MASK) != S35390A_INT2_MODE_ALARM) {
 324                 /*
 325                  * When the alarm isn't enabled, the register to configure
 326                  * the alarm time isn't accessible.
 327                  */
 328                 alm->enabled = 0;
 329                 return 0;
 330         } else {
 331                 alm->enabled = 1;
 332         }
 333
 334         err = s35390a_get_reg(s35390a, S35390A_CMD_INT2_REG1, buf, sizeof(buf));
 335         if (err < 0)
 336                 return err;
 337
 338         /* This chip returns the bits of each byte in reverse order */
 339         for (i = 0; i < 3; ++i)
 340                 buf[i] = bitrev8(buf[i]);
 341
 342         /*
 343          * B0 of the three matching registers is an enable flag. Iff it is set
 344          * the configured value is used for matching.
 345          */
 346         if (buf[S35390A_ALRM_BYTE_WDAY] & 0x80)
 347                 alm->time.tm_wday =
 348                         bcd2bin(buf[S35390A_ALRM_BYTE_WDAY] & ~0x80);
 349
 350         if (buf[S35390A_ALRM_BYTE_HOURS] & 0x80)
 351                 alm->time.tm_hour =
 352                         s35390a_reg2hr(s35390a,
 353                                        buf[S35390A_ALRM_BYTE_HOURS] & ~0x80);
 354
 355         if (buf[S35390A_ALRM_BYTE_MINS] & 0x80)
 356                 alm->time.tm_min = bcd2bin(buf[S35390A_ALRM_BYTE_MINS] & ~0x80);
 357
 358         /* alarm triggers always at s=0 */
 359         alm->time.tm_sec = 0;
 360
 361         dev_dbg(&client->dev, "%s: alm is mins=%d, hours=%d, wday=%d\n",
 362                         __func__, alm->time.tm_min, alm->time.tm_hour,
 363                         alm->time.tm_wday);
 364
 365         return 0;
 366 }
 367
 368 static int s35390a_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
 369 {
 370         return s35390a_read_alarm(to_i2c_client(dev), alm);
 371 }
 372
 373 static int s35390a_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
 374 {
 375         return s35390a_set_alarm(to_i2c_client(dev), alm);
 376 }
 377
 378 static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
 379 {
 380         return s35390a_get_datetime(to_i2c_client(dev), tm);
 381 }
 382
 383 static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
 384 {
 385         return s35390a_set_datetime(to_i2c_client(dev), tm);
 386 }
 387
 388 static const struct rtc_class_ops s35390a_rtc_ops = {
 389         .read_time      = s35390a_rtc_read_time,
 390         .set_time       = s35390a_rtc_set_time,
 391         .set_alarm      = s35390a_rtc_set_alarm,
 392         .read_alarm     = s35390a_rtc_read_alarm,
 393
 394 };
 395
 396 static struct i2c_driver s35390a_driver;
 397
 398 static int s35390a_probe(struct i2c_client *client,
 399                          const struct i2c_device_id *id)
 400 {
 401         int err, err_reset;
 402         unsigned int i;
 403         struct s35390a *s35390a;
 404         struct rtc_time tm;
 405         char buf, status1;
 406
 407         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
 408                 err = -ENODEV;
 409                 goto exit;
 410         }
 411
 412         s35390a = devm_kzalloc(&client->dev, sizeof(struct s35390a),
 413                                 GFP_KERNEL);
 414         if (!s35390a) {
 415                 err = -ENOMEM;
 416                 goto exit;
 417         }
 418
 419         s35390a->client[0] = client;
 420         i2c_set_clientdata(client, s35390a);
 421
 422         /* This chip uses multiple addresses, use dummy devices for them */
 423         for (i = 1; i < 8; ++i) {
 424                 s35390a->client[i] = i2c_new_dummy(client->adapter,
 425                                         client->addr + i);
 426                 if (!s35390a->client[i]) {
 427                         dev_err(&client->dev, "Address %02x unavailable\n",
 428                                                 client->addr + i);
 429                         err = -EBUSY;
 430                         goto exit_dummy;
 431                 }
 432         }
 433
 434         err_reset = s35390a_reset(s35390a, &status1);
 435         if (err_reset < 0) {
 436                 err = err_reset;
 437                 dev_err(&client->dev, "error resetting chip\n");
 438                 goto exit_dummy;
 439         }
 440
 441         if (status1 & S35390A_FLAG_24H)
 442                 s35390a->twentyfourhour = 1;
 443         else
 444                 s35390a->twentyfourhour = 0;
 445
 446         if (status1 & S35390A_FLAG_INT2) {
 447                 /* disable alarm (and maybe test mode) */
 448                 buf = 0;
 449                 err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &buf, 1);
 450                 if (err < 0) {
 451                         dev_err(&client->dev, "error disabling alarm");
 452                         goto exit_dummy;
 453                 }
 454         } else {
 455                 err = s35390a_disable_test_mode(s35390a);
 456                 if (err < 0) {
 457                         dev_err(&client->dev, "error disabling test mode\n");
 458                         goto exit_dummy;
 459                 }
 460         }
 461
 462         if (err_reset > 0 || s35390a_get_datetime(client, &tm) < 0)
 463                 dev_warn(&client->dev, "clock needs to be set\n");
 464
 465         device_set_wakeup_capable(&client->dev, 1);
 466
 467         s35390a->rtc = devm_rtc_device_register(&client->dev,
 468                                         s35390a_driver.driver.name,
 469                                         &s35390a_rtc_ops, THIS_MODULE);
 470
 471         if (IS_ERR(s35390a->rtc)) {
 472                 err = PTR_ERR(s35390a->rtc);
 473                 goto exit_dummy;
 474         }
 475
 476         if (status1 & S35390A_FLAG_INT2)
 477                 rtc_update_irq(s35390a->rtc, 1, RTC_AF);
 478
 479         return 0;
 480
 481 exit_dummy:
 482         for (i = 1; i < 8; ++i)
 483                 if (s35390a->client[i])
 484                         i2c_unregister_device(s35390a->client[i]);
 485
 486 exit:
 487         return err;
 488 }
 489
 490 static int s35390a_remove(struct i2c_client *client)
 491 {
 492         unsigned int i;
 493         struct s35390a *s35390a = i2c_get_clientdata(client);
 494
 495         for (i = 1; i < 8; ++i)
 496                 if (s35390a->client[i])
 497                         i2c_unregister_device(s35390a->client[i]);
 498
 499         return 0;
 500 }
 501
 502 static struct i2c_driver s35390a_driver = {
 503         .driver         = {
 504                 .name   = "rtc-s35390a",
 505         },
 506         .probe          = s35390a_probe,
 507         .remove         = s35390a_remove,
 508         .id_table       = s35390a_id,
 509 };
 510
 511 module_i2c_driver(s35390a_driver);
 512
 513 MODULE_AUTHOR("Byron Bradley <byron.bbradley@gmail.com>");
 514 MODULE_DESCRIPTION("S35390A RTC driver");
 515 MODULE_LICENSE("GPL");