git.oblomov.eu Git - linux-2.6/blob - drivers/rtc/rtc-ds1307.c

   1 /*
   2  * rtc-ds1307.c - RTC driver for some mostly-compatible I2C chips.
   3  *
   4  *  Copyright (C) 2005 James Chapman (ds1337 core)
   5  *  Copyright (C) 2006 David Brownell
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/slab.h>
  15 #include <linux/i2c.h>
  16 #include <linux/string.h>
  17 #include <linux/rtc.h>
  18 #include <linux/bcd.h>
  19
  20
  21
  22 /* We can't determine type by probing, but if we expect pre-Linux code
  23  * to have set the chip up as a clock (turning on the oscillator and
  24  * setting the date and time), Linux can ignore the non-clock features.
  25  * That's a natural job for a factory or repair bench.
  26  */
  27 enum ds_type {
  28         ds_1307,
  29         ds_1337,
  30         ds_1338,
  31         ds_1339,
  32         ds_1340,
  33         m41t00,
  34         // rs5c372 too?  different address...
  35 };
  36
  37
  38 /* RTC registers don't differ much, except for the century flag */
  39 #define DS1307_REG_SECS         0x00    /* 00-59 */
  40 #       define DS1307_BIT_CH            0x80
  41 #       define DS1340_BIT_nEOSC         0x80
  42 #define DS1307_REG_MIN          0x01    /* 00-59 */
  43 #define DS1307_REG_HOUR         0x02    /* 00-23, or 1-12{am,pm} */
  44 #       define DS1307_BIT_12HR          0x40    /* in REG_HOUR */
  45 #       define DS1307_BIT_PM            0x20    /* in REG_HOUR */
  46 #       define DS1340_BIT_CENTURY_EN    0x80    /* in REG_HOUR */
  47 #       define DS1340_BIT_CENTURY       0x40    /* in REG_HOUR */
  48 #define DS1307_REG_WDAY         0x03    /* 01-07 */
  49 #define DS1307_REG_MDAY         0x04    /* 01-31 */
  50 #define DS1307_REG_MONTH        0x05    /* 01-12 */
  51 #       define DS1337_BIT_CENTURY       0x80    /* in REG_MONTH */
  52 #define DS1307_REG_YEAR         0x06    /* 00-99 */
  53
  54 /* Other registers (control, status, alarms, trickle charge, NVRAM, etc)
  55  * start at 7, and they differ a LOT. Only control and status matter for
  56  * basic RTC date and time functionality; be careful using them.
  57  */
  58 #define DS1307_REG_CONTROL      0x07            /* or ds1338 */
  59 #       define DS1307_BIT_OUT           0x80
  60 #       define DS1338_BIT_OSF           0x20
  61 #       define DS1307_BIT_SQWE          0x10
  62 #       define DS1307_BIT_RS1           0x02
  63 #       define DS1307_BIT_RS0           0x01
  64 #define DS1337_REG_CONTROL      0x0e
  65 #       define DS1337_BIT_nEOSC         0x80
  66 #       define DS1339_BIT_BBSQI         0x20
  67 #       define DS1337_BIT_RS2           0x10
  68 #       define DS1337_BIT_RS1           0x08
  69 #       define DS1337_BIT_INTCN         0x04
  70 #       define DS1337_BIT_A2IE          0x02
  71 #       define DS1337_BIT_A1IE          0x01
  72 #define DS1340_REG_CONTROL      0x07
  73 #       define DS1340_BIT_OUT           0x80
  74 #       define DS1340_BIT_FT            0x40
  75 #       define DS1340_BIT_CALIB_SIGN    0x20
  76 #       define DS1340_M_CALIBRATION     0x1f
  77 #define DS1340_REG_FLAG         0x09
  78 #       define DS1340_BIT_OSF           0x80
  79 #define DS1337_REG_STATUS       0x0f
  80 #       define DS1337_BIT_OSF           0x80
  81 #       define DS1337_BIT_A2I           0x02
  82 #       define DS1337_BIT_A1I           0x01
  83 #define DS1339_REG_ALARM1_SECS  0x07
  84 #define DS1339_REG_TRICKLE      0x10
  85
  86
  87
  88 struct ds1307 {
  89         u8                      regs[11];
  90         enum ds_type            type;
  91         unsigned long           flags;
  92 #define HAS_NVRAM       0               /* bit 0 == sysfs file active */
  93 #define HAS_ALARM       1               /* bit 1 == irq claimed */
  94         struct i2c_client       *client;
  95         struct rtc_device       *rtc;
  96         struct work_struct      work;
  97 };
  98
  99 struct chip_desc {
 100         unsigned                nvram56:1;
 101         unsigned                alarm:1;
 102 };
 103
 104 static const struct chip_desc chips[] = {
 105 [ds_1307] = {
 106         .nvram56        = 1,
 107 },
 108 [ds_1337] = {
 109         .alarm          = 1,
 110 },
 111 [ds_1338] = {
 112         .nvram56        = 1,
 113 },
 114 [ds_1339] = {
 115         .alarm          = 1,
 116 },
 117 [ds_1340] = {
 118 },
 119 [m41t00] = {
 120 }, };
 121
 122 static const struct i2c_device_id ds1307_id[] = {
 123         { "ds1307", ds_1307 },
 124         { "ds1337", ds_1337 },
 125         { "ds1338", ds_1338 },
 126         { "ds1339", ds_1339 },
 127         { "ds1340", ds_1340 },
 128         { "m41t00", m41t00 },
 129         { }
 130 };
 131 MODULE_DEVICE_TABLE(i2c, ds1307_id);
 132
 133 /*----------------------------------------------------------------------*/
 134
 135 /*
 136  * The IRQ logic includes a "real" handler running in IRQ context just
 137  * long enough to schedule this workqueue entry.   We need a task context
 138  * to talk to the RTC, since I2C I/O calls require that; and disable the
 139  * IRQ until we clear its status on the chip, so that this handler can
 140  * work with any type of triggering (not just falling edge).
 141  *
 142  * The ds1337 and ds1339 both have two alarms, but we only use the first
 143  * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
 144  * signal; ds1339 chips have only one alarm signal.
 145  */
 146 static void ds1307_work(struct work_struct *work)
 147 {
 148         struct ds1307           *ds1307;
 149         struct i2c_client       *client;
 150         struct mutex            *lock;
 151         int                     stat, control;
 152
 153         ds1307 = container_of(work, struct ds1307, work);
 154         client = ds1307->client;
 155         lock = &ds1307->rtc->ops_lock;
 156
 157         mutex_lock(lock);
 158         stat = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
 159         if (stat < 0)
 160                 goto out;
 161
 162         if (stat & DS1337_BIT_A1I) {
 163                 stat &= ~DS1337_BIT_A1I;
 164                 i2c_smbus_write_byte_data(client, DS1337_REG_STATUS, stat);
 165
 166                 control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
 167                 if (control < 0)
 168                         goto out;
 169
 170                 control &= ~DS1337_BIT_A1IE;
 171                 i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, control);
 172
 173                 /* rtc_update_irq() assumes that it is called
 174                  * from IRQ-disabled context.
 175                  */
 176                 local_irq_disable();
 177                 rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
 178                 local_irq_enable();
 179         }
 180
 181 out:
 182         if (test_bit(HAS_ALARM, &ds1307->flags))
 183                 enable_irq(client->irq);
 184         mutex_unlock(lock);
 185 }
 186
 187 static irqreturn_t ds1307_irq(int irq, void *dev_id)
 188 {
 189         struct i2c_client       *client = dev_id;
 190         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 191
 192         disable_irq_nosync(irq);
 193         schedule_work(&ds1307->work);
 194         return IRQ_HANDLED;
 195 }
 196
 197 /*----------------------------------------------------------------------*/
 198
 199 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
 200 {
 201         struct ds1307   *ds1307 = dev_get_drvdata(dev);
 202         int             tmp;
 203
 204         /* read the RTC date and time registers all at once */
 205         tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
 206                 DS1307_REG_SECS, 7, ds1307->regs);
 207         if (tmp != 7) {
 208                 dev_err(dev, "%s error %d\n", "read", tmp);
 209                 return -EIO;
 210         }
 211
 212         dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
 213                         "read",
 214                         ds1307->regs[0], ds1307->regs[1],
 215                         ds1307->regs[2], ds1307->regs[3],
 216                         ds1307->regs[4], ds1307->regs[5],
 217                         ds1307->regs[6]);
 218
 219         t->tm_sec = bcd2bin(ds1307->regs[DS1307_REG_SECS] & 0x7f);
 220         t->tm_min = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f);
 221         tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
 222         t->tm_hour = bcd2bin(tmp);
 223         t->tm_wday = bcd2bin(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
 224         t->tm_mday = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
 225         tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
 226         t->tm_mon = bcd2bin(tmp) - 1;
 227
 228         /* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
 229         t->tm_year = bcd2bin(ds1307->regs[DS1307_REG_YEAR]) + 100;
 230
 231         dev_dbg(dev, "%s secs=%d, mins=%d, "
 232                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
 233                 "read", t->tm_sec, t->tm_min,
 234                 t->tm_hour, t->tm_mday,
 235                 t->tm_mon, t->tm_year, t->tm_wday);
 236
 237         /* initial clock setting can be undefined */
 238         return rtc_valid_tm(t);
 239 }
 240
 241 static int ds1307_set_time(struct device *dev, struct rtc_time *t)
 242 {
 243         struct ds1307   *ds1307 = dev_get_drvdata(dev);
 244         int             result;
 245         int             tmp;
 246         u8              *buf = ds1307->regs;
 247
 248         dev_dbg(dev, "%s secs=%d, mins=%d, "
 249                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
 250                 "write", t->tm_sec, t->tm_min,
 251                 t->tm_hour, t->tm_mday,
 252                 t->tm_mon, t->tm_year, t->tm_wday);
 253
 254         buf[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
 255         buf[DS1307_REG_MIN] = bin2bcd(t->tm_min);
 256         buf[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
 257         buf[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
 258         buf[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
 259         buf[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
 260
 261         /* assume 20YY not 19YY */
 262         tmp = t->tm_year - 100;
 263         buf[DS1307_REG_YEAR] = bin2bcd(tmp);
 264
 265         switch (ds1307->type) {
 266         case ds_1337:
 267         case ds_1339:
 268                 buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
 269                 break;
 270         case ds_1340:
 271                 buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
 272                                 | DS1340_BIT_CENTURY;
 273                 break;
 274         default:
 275                 break;
 276         }
 277
 278         dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
 279                 "write", buf[0], buf[1], buf[2], buf[3],
 280                 buf[4], buf[5], buf[6]);
 281
 282         result = i2c_smbus_write_i2c_block_data(ds1307->client, 0, 7, buf);
 283         if (result < 0) {
 284                 dev_err(dev, "%s error %d\n", "write", result);
 285                 return result;
 286         }
 287         return 0;
 288 }
 289
 290 static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 291 {
 292         struct i2c_client       *client = to_i2c_client(dev);
 293         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 294         int                     ret;
 295
 296         if (!test_bit(HAS_ALARM, &ds1307->flags))
 297                 return -EINVAL;
 298
 299         /* read all ALARM1, ALARM2, and status registers at once */
 300         ret = i2c_smbus_read_i2c_block_data(client,
 301                         DS1339_REG_ALARM1_SECS, 9, ds1307->regs);
 302         if (ret != 9) {
 303                 dev_err(dev, "%s error %d\n", "alarm read", ret);
 304                 return -EIO;
 305         }
 306
 307         dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
 308                         "alarm read",
 309                         ds1307->regs[0], ds1307->regs[1],
 310                         ds1307->regs[2], ds1307->regs[3],
 311                         ds1307->regs[4], ds1307->regs[5],
 312                         ds1307->regs[6], ds1307->regs[7],
 313                         ds1307->regs[8]);
 314
 315         /* report alarm time (ALARM1); assume 24 hour and day-of-month modes,
 316          * and that all four fields are checked matches
 317          */
 318         t->time.tm_sec = bcd2bin(ds1307->regs[0] & 0x7f);
 319         t->time.tm_min = bcd2bin(ds1307->regs[1] & 0x7f);
 320         t->time.tm_hour = bcd2bin(ds1307->regs[2] & 0x3f);
 321         t->time.tm_mday = bcd2bin(ds1307->regs[3] & 0x3f);
 322         t->time.tm_mon = -1;
 323         t->time.tm_year = -1;
 324         t->time.tm_wday = -1;
 325         t->time.tm_yday = -1;
 326         t->time.tm_isdst = -1;
 327
 328         /* ... and status */
 329         t->enabled = !!(ds1307->regs[7] & DS1337_BIT_A1IE);
 330         t->pending = !!(ds1307->regs[8] & DS1337_BIT_A1I);
 331
 332         dev_dbg(dev, "%s secs=%d, mins=%d, "
 333                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
 334                 "alarm read", t->time.tm_sec, t->time.tm_min,
 335                 t->time.tm_hour, t->time.tm_mday,
 336                 t->enabled, t->pending);
 337
 338         return 0;
 339 }
 340
 341 static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 342 {
 343         struct i2c_client       *client = to_i2c_client(dev);
 344         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 345         unsigned char           *buf = ds1307->regs;
 346         u8                      control, status;
 347         int                     ret;
 348
 349         if (!test_bit(HAS_ALARM, &ds1307->flags))
 350                 return -EINVAL;
 351
 352         dev_dbg(dev, "%s secs=%d, mins=%d, "
 353                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
 354                 "alarm set", t->time.tm_sec, t->time.tm_min,
 355                 t->time.tm_hour, t->time.tm_mday,
 356                 t->enabled, t->pending);
 357
 358         /* read current status of both alarms and the chip */
 359         ret = i2c_smbus_read_i2c_block_data(client,
 360                         DS1339_REG_ALARM1_SECS, 9, buf);
 361         if (ret != 9) {
 362                 dev_err(dev, "%s error %d\n", "alarm write", ret);
 363                 return -EIO;
 364         }
 365         control = ds1307->regs[7];
 366         status = ds1307->regs[8];
 367
 368         dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
 369                         "alarm set (old status)",
 370                         ds1307->regs[0], ds1307->regs[1],
 371                         ds1307->regs[2], ds1307->regs[3],
 372                         ds1307->regs[4], ds1307->regs[5],
 373                         ds1307->regs[6], control, status);
 374
 375         /* set ALARM1, using 24 hour and day-of-month modes */
 376         buf[0] = bin2bcd(t->time.tm_sec);
 377         buf[1] = bin2bcd(t->time.tm_min);
 378         buf[2] = bin2bcd(t->time.tm_hour);
 379         buf[3] = bin2bcd(t->time.tm_mday);
 380
 381         /* set ALARM2 to non-garbage */
 382         buf[4] = 0;
 383         buf[5] = 0;
 384         buf[6] = 0;
 385
 386         /* optionally enable ALARM1 */
 387         buf[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
 388         if (t->enabled) {
 389                 dev_dbg(dev, "alarm IRQ armed\n");
 390                 buf[7] |= DS1337_BIT_A1IE;      /* only ALARM1 is used */
 391         }
 392         buf[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
 393
 394         ret = i2c_smbus_write_i2c_block_data(client,
 395                         DS1339_REG_ALARM1_SECS, 9, buf);
 396         if (ret < 0) {
 397                 dev_err(dev, "can't set alarm time\n");
 398                 return ret;
 399         }
 400
 401         return 0;
 402 }
 403
 404 static int ds1307_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 405 {
 406         struct i2c_client       *client = to_i2c_client(dev);
 407         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 408         int                     ret;
 409
 410         switch (cmd) {
 411         case RTC_AIE_OFF:
 412                 if (!test_bit(HAS_ALARM, &ds1307->flags))
 413                         return -ENOTTY;
 414
 415                 ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
 416                 if (ret < 0)
 417                         return ret;
 418
 419                 ret &= ~DS1337_BIT_A1IE;
 420
 421                 ret = i2c_smbus_write_byte_data(client,
 422                                                 DS1337_REG_CONTROL, ret);
 423                 if (ret < 0)
 424                         return ret;
 425
 426                 break;
 427
 428         case RTC_AIE_ON:
 429                 if (!test_bit(HAS_ALARM, &ds1307->flags))
 430                         return -ENOTTY;
 431
 432                 ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
 433                 if (ret < 0)
 434                         return ret;
 435
 436                 ret |= DS1337_BIT_A1IE;
 437
 438                 ret = i2c_smbus_write_byte_data(client,
 439                                                 DS1337_REG_CONTROL, ret);
 440                 if (ret < 0)
 441                         return ret;
 442
 443                 break;
 444
 445         default:
 446                 return -ENOIOCTLCMD;
 447         }
 448
 449         return 0;
 450 }
 451
 452 static const struct rtc_class_ops ds13xx_rtc_ops = {
 453         .read_time      = ds1307_get_time,
 454         .set_time       = ds1307_set_time,
 455         .read_alarm     = ds1337_read_alarm,
 456         .set_alarm      = ds1337_set_alarm,
 457         .ioctl          = ds1307_ioctl,
 458 };
 459
 460 /*----------------------------------------------------------------------*/
 461
 462 #define NVRAM_SIZE      56
 463
 464 static ssize_t
 465 ds1307_nvram_read(struct kobject *kobj, struct bin_attribute *attr,
 466                 char *buf, loff_t off, size_t count)
 467 {
 468         struct i2c_client       *client;
 469         struct ds1307           *ds1307;
 470         int                     result;
 471
 472         client = kobj_to_i2c_client(kobj);
 473         ds1307 = i2c_get_clientdata(client);
 474
 475         if (unlikely(off >= NVRAM_SIZE))
 476                 return 0;
 477         if ((off + count) > NVRAM_SIZE)
 478                 count = NVRAM_SIZE - off;
 479         if (unlikely(!count))
 480                 return count;
 481
 482         result = i2c_smbus_read_i2c_block_data(client, 8 + off, count, buf);
 483         if (result < 0)
 484                 dev_err(&client->dev, "%s error %d\n", "nvram read", result);
 485         return result;
 486 }
 487
 488 static ssize_t
 489 ds1307_nvram_write(struct kobject *kobj, struct bin_attribute *attr,
 490                 char *buf, loff_t off, size_t count)
 491 {
 492         struct i2c_client       *client;
 493         int                     result;
 494
 495         client = kobj_to_i2c_client(kobj);
 496
 497         if (unlikely(off >= NVRAM_SIZE))
 498                 return -EFBIG;
 499         if ((off + count) > NVRAM_SIZE)
 500                 count = NVRAM_SIZE - off;
 501         if (unlikely(!count))
 502                 return count;
 503
 504         result = i2c_smbus_write_i2c_block_data(client, 8 + off, count, buf);
 505         if (result < 0) {
 506                 dev_err(&client->dev, "%s error %d\n", "nvram write", result);
 507                 return result;
 508         }
 509         return count;
 510 }
 511
 512 static struct bin_attribute nvram = {
 513         .attr = {
 514                 .name   = "nvram",
 515                 .mode   = S_IRUGO | S_IWUSR,
 516         },
 517
 518         .read   = ds1307_nvram_read,
 519         .write  = ds1307_nvram_write,
 520         .size   = NVRAM_SIZE,
 521 };
 522
 523 /*----------------------------------------------------------------------*/
 524
 525 static struct i2c_driver ds1307_driver;
 526
 527 static int __devinit ds1307_probe(struct i2c_client *client,
 528                                   const struct i2c_device_id *id)
 529 {
 530         struct ds1307           *ds1307;
 531         int                     err = -ENODEV;
 532         int                     tmp;
 533         const struct chip_desc  *chip = &chips[id->driver_data];
 534         struct i2c_adapter      *adapter = to_i2c_adapter(client->dev.parent);
 535         int                     want_irq = false;
 536         unsigned char           *buf;
 537
 538         if (!i2c_check_functionality(adapter,
 539                         I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
 540                         I2C_FUNC_SMBUS_I2C_BLOCK))
 541                 return -EIO;
 542
 543         if (!(ds1307 = kzalloc(sizeof(struct ds1307), GFP_KERNEL)))
 544                 return -ENOMEM;
 545
 546         ds1307->client = client;
 547         i2c_set_clientdata(client, ds1307);
 548         ds1307->type = id->driver_data;
 549         buf = ds1307->regs;
 550
 551         switch (ds1307->type) {
 552         case ds_1337:
 553         case ds_1339:
 554                 /* has IRQ? */
 555                 if (ds1307->client->irq > 0 && chip->alarm) {
 556                         INIT_WORK(&ds1307->work, ds1307_work);
 557                         want_irq = true;
 558                 }
 559                 /* get registers that the "rtc" read below won't read... */
 560                 tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
 561                                 DS1337_REG_CONTROL, 2, buf);
 562                 if (tmp != 2) {
 563                         pr_debug("read error %d\n", tmp);
 564                         err = -EIO;
 565                         goto exit_free;
 566                 }
 567
 568                 /* oscillator off?  turn it on, so clock can tick. */
 569                 if (ds1307->regs[0] & DS1337_BIT_nEOSC)
 570                         ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
 571
 572                 /* Using IRQ?  Disable the square wave and both alarms.
 573                  * For ds1339, be sure alarms can trigger when we're
 574                  * running on Vbackup (BBSQI); we assume ds1337 will
 575                  * ignore that bit
 576                  */
 577                 if (want_irq) {
 578                         ds1307->regs[0] |= DS1337_BIT_INTCN | DS1339_BIT_BBSQI;
 579                         ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
 580                 }
 581
 582                 i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
 583                                                         ds1307->regs[0]);
 584
 585                 /* oscillator fault?  clear flag, and warn */
 586                 if (ds1307->regs[1] & DS1337_BIT_OSF) {
 587                         i2c_smbus_write_byte_data(client, DS1337_REG_STATUS,
 588                                 ds1307->regs[1] & ~DS1337_BIT_OSF);
 589                         dev_warn(&client->dev, "SET TIME!\n");
 590                 }
 591                 break;
 592         default:
 593                 break;
 594         }
 595
 596 read_rtc:
 597         /* read RTC registers */
 598         tmp = i2c_smbus_read_i2c_block_data(ds1307->client, 0, 8, buf);
 599         if (tmp != 8) {
 600                 pr_debug("read error %d\n", tmp);
 601                 err = -EIO;
 602                 goto exit_free;
 603         }
 604
 605         /* minimal sanity checking; some chips (like DS1340) don't
 606          * specify the extra bits as must-be-zero, but there are
 607          * still a few values that are clearly out-of-range.
 608          */
 609         tmp = ds1307->regs[DS1307_REG_SECS];
 610         switch (ds1307->type) {
 611         case ds_1307:
 612         case m41t00:
 613                 /* clock halted?  turn it on, so clock can tick. */
 614                 if (tmp & DS1307_BIT_CH) {
 615                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
 616                         dev_warn(&client->dev, "SET TIME!\n");
 617                         goto read_rtc;
 618                 }
 619                 break;
 620         case ds_1338:
 621                 /* clock halted?  turn it on, so clock can tick. */
 622                 if (tmp & DS1307_BIT_CH)
 623                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
 624
 625                 /* oscillator fault?  clear flag, and warn */
 626                 if (ds1307->regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
 627                         i2c_smbus_write_byte_data(client, DS1307_REG_CONTROL,
 628                                         ds1307->regs[DS1307_REG_CONTROL]
 629                                         & ~DS1338_BIT_OSF);
 630                         dev_warn(&client->dev, "SET TIME!\n");
 631                         goto read_rtc;
 632                 }
 633                 break;
 634         case ds_1340:
 635                 /* clock halted?  turn it on, so clock can tick. */
 636                 if (tmp & DS1340_BIT_nEOSC)
 637                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
 638
 639                 tmp = i2c_smbus_read_byte_data(client, DS1340_REG_FLAG);
 640                 if (tmp < 0) {
 641                         pr_debug("read error %d\n", tmp);
 642                         err = -EIO;
 643                         goto exit_free;
 644                 }
 645
 646                 /* oscillator fault?  clear flag, and warn */
 647                 if (tmp & DS1340_BIT_OSF) {
 648                         i2c_smbus_write_byte_data(client, DS1340_REG_FLAG, 0);
 649                         dev_warn(&client->dev, "SET TIME!\n");
 650                 }
 651                 break;
 652         case ds_1337:
 653         case ds_1339:
 654                 break;
 655         }
 656
 657         tmp = ds1307->regs[DS1307_REG_HOUR];
 658         switch (ds1307->type) {
 659         case ds_1340:
 660         case m41t00:
 661                 /* NOTE: ignores century bits; fix before deploying
 662                  * systems that will run through year 2100.
 663                  */
 664                 break;
 665         default:
 666                 if (!(tmp & DS1307_BIT_12HR))
 667                         break;
 668
 669                 /* Be sure we're in 24 hour mode.  Multi-master systems
 670                  * take note...
 671                  */
 672                 tmp = bcd2bin(tmp & 0x1f);
 673                 if (tmp == 12)
 674                         tmp = 0;
 675                 if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
 676                         tmp += 12;
 677                 i2c_smbus_write_byte_data(client,
 678                                 DS1307_REG_HOUR,
 679                                 bin2bcd(tmp));
 680         }
 681
 682         ds1307->rtc = rtc_device_register(client->name, &client->dev,
 683                                 &ds13xx_rtc_ops, THIS_MODULE);
 684         if (IS_ERR(ds1307->rtc)) {
 685                 err = PTR_ERR(ds1307->rtc);
 686                 dev_err(&client->dev,
 687                         "unable to register the class device\n");
 688                 goto exit_free;
 689         }
 690
 691         if (want_irq) {
 692                 err = request_irq(client->irq, ds1307_irq, 0,
 693                           ds1307->rtc->name, client);
 694                 if (err) {
 695                         dev_err(&client->dev,
 696                                 "unable to request IRQ!\n");
 697                         goto exit_irq;
 698                 }
 699                 set_bit(HAS_ALARM, &ds1307->flags);
 700                 dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
 701         }
 702
 703         if (chip->nvram56) {
 704                 err = sysfs_create_bin_file(&client->dev.kobj, &nvram);
 705                 if (err == 0) {
 706                         set_bit(HAS_NVRAM, &ds1307->flags);
 707                         dev_info(&client->dev, "56 bytes nvram\n");
 708                 }
 709         }
 710
 711         return 0;
 712
 713 exit_irq:
 714         if (ds1307->rtc)
 715                 rtc_device_unregister(ds1307->rtc);
 716 exit_free:
 717         kfree(ds1307);
 718         return err;
 719 }
 720
 721 static int __devexit ds1307_remove(struct i2c_client *client)
 722 {
 723         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 724
 725         if (test_and_clear_bit(HAS_ALARM, &ds1307->flags)) {
 726                 free_irq(client->irq, client);
 727                 cancel_work_sync(&ds1307->work);
 728         }
 729
 730         if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags))
 731                 sysfs_remove_bin_file(&client->dev.kobj, &nvram);
 732
 733         rtc_device_unregister(ds1307->rtc);
 734         kfree(ds1307);
 735         return 0;
 736 }
 737
 738 static struct i2c_driver ds1307_driver = {
 739         .driver = {
 740                 .name   = "rtc-ds1307",
 741                 .owner  = THIS_MODULE,
 742         },
 743         .probe          = ds1307_probe,
 744         .remove         = __devexit_p(ds1307_remove),
 745         .id_table       = ds1307_id,
 746 };
 747
 748 static int __init ds1307_init(void)
 749 {
 750         return i2c_add_driver(&ds1307_driver);
 751 }
 752 module_init(ds1307_init);
 753
 754 static void __exit ds1307_exit(void)
 755 {
 756         i2c_del_driver(&ds1307_driver);
 757 }
 758 module_exit(ds1307_exit);
 759
 760 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
 761 MODULE_LICENSE("GPL");