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  *  Copyright (C) 2009 Matthias Fuchs (rx8025 support)
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15 #include <linux/slab.h>
  16 #include <linux/i2c.h>
  17 #include <linux/string.h>
  18 #include <linux/rtc.h>
  19 #include <linux/bcd.h>
  20
  21
  22
  23 /* We can't determine type by probing, but if we expect pre-Linux code
  24  * to have set the chip up as a clock (turning on the oscillator and
  25  * setting the date and time), Linux can ignore the non-clock features.
  26  * That's a natural job for a factory or repair bench.
  27  */
  28 enum ds_type {
  29         ds_1307,
  30         ds_1337,
  31         ds_1338,
  32         ds_1339,
  33         ds_1340,
  34         ds_1388,
  35         ds_3231,
  36         m41t00,
  37         rx_8025,
  38         // rs5c372 too?  different address...
  39 };
  40
  41
  42 /* RTC registers don't differ much, except for the century flag */
  43 #define DS1307_REG_SECS         0x00    /* 00-59 */
  44 #       define DS1307_BIT_CH            0x80
  45 #       define DS1340_BIT_nEOSC         0x80
  46 #define DS1307_REG_MIN          0x01    /* 00-59 */
  47 #define DS1307_REG_HOUR         0x02    /* 00-23, or 1-12{am,pm} */
  48 #       define DS1307_BIT_12HR          0x40    /* in REG_HOUR */
  49 #       define DS1307_BIT_PM            0x20    /* in REG_HOUR */
  50 #       define DS1340_BIT_CENTURY_EN    0x80    /* in REG_HOUR */
  51 #       define DS1340_BIT_CENTURY       0x40    /* in REG_HOUR */
  52 #define DS1307_REG_WDAY         0x03    /* 01-07 */
  53 #define DS1307_REG_MDAY         0x04    /* 01-31 */
  54 #define DS1307_REG_MONTH        0x05    /* 01-12 */
  55 #       define DS1337_BIT_CENTURY       0x80    /* in REG_MONTH */
  56 #define DS1307_REG_YEAR         0x06    /* 00-99 */
  57
  58 /* Other registers (control, status, alarms, trickle charge, NVRAM, etc)
  59  * start at 7, and they differ a LOT. Only control and status matter for
  60  * basic RTC date and time functionality; be careful using them.
  61  */
  62 #define DS1307_REG_CONTROL      0x07            /* or ds1338 */
  63 #       define DS1307_BIT_OUT           0x80
  64 #       define DS1338_BIT_OSF           0x20
  65 #       define DS1307_BIT_SQWE          0x10
  66 #       define DS1307_BIT_RS1           0x02
  67 #       define DS1307_BIT_RS0           0x01
  68 #define DS1337_REG_CONTROL      0x0e
  69 #       define DS1337_BIT_nEOSC         0x80
  70 #       define DS1339_BIT_BBSQI         0x20
  71 #       define DS3231_BIT_BBSQW         0x40 /* same as BBSQI */
  72 #       define DS1337_BIT_RS2           0x10
  73 #       define DS1337_BIT_RS1           0x08
  74 #       define DS1337_BIT_INTCN         0x04
  75 #       define DS1337_BIT_A2IE          0x02
  76 #       define DS1337_BIT_A1IE          0x01
  77 #define DS1340_REG_CONTROL      0x07
  78 #       define DS1340_BIT_OUT           0x80
  79 #       define DS1340_BIT_FT            0x40
  80 #       define DS1340_BIT_CALIB_SIGN    0x20
  81 #       define DS1340_M_CALIBRATION     0x1f
  82 #define DS1340_REG_FLAG         0x09
  83 #       define DS1340_BIT_OSF           0x80
  84 #define DS1337_REG_STATUS       0x0f
  85 #       define DS1337_BIT_OSF           0x80
  86 #       define DS1337_BIT_A2I           0x02
  87 #       define DS1337_BIT_A1I           0x01
  88 #define DS1339_REG_ALARM1_SECS  0x07
  89 #define DS1339_REG_TRICKLE      0x10
  90
  91 #define RX8025_REG_CTRL1        0x0e
  92 #       define RX8025_BIT_2412          0x20
  93 #define RX8025_REG_CTRL2        0x0f
  94 #       define RX8025_BIT_PON           0x10
  95 #       define RX8025_BIT_VDET          0x40
  96 #       define RX8025_BIT_XST           0x20
  97
  98
  99 struct ds1307 {
 100         u8                      offset; /* register's offset */
 101         u8                      regs[11];
 102         enum ds_type            type;
 103         unsigned long           flags;
 104 #define HAS_NVRAM       0               /* bit 0 == sysfs file active */
 105 #define HAS_ALARM       1               /* bit 1 == irq claimed */
 106         struct i2c_client       *client;
 107         struct rtc_device       *rtc;
 108         struct work_struct      work;
 109         s32 (*read_block_data)(const struct i2c_client *client, u8 command,
 110                                u8 length, u8 *values);
 111         s32 (*write_block_data)(const struct i2c_client *client, u8 command,
 112                                 u8 length, const u8 *values);
 113 };
 114
 115 struct chip_desc {
 116         unsigned                nvram56:1;
 117         unsigned                alarm:1;
 118 };
 119
 120 static const struct chip_desc chips[] = {
 121 [ds_1307] = {
 122         .nvram56        = 1,
 123 },
 124 [ds_1337] = {
 125         .alarm          = 1,
 126 },
 127 [ds_1338] = {
 128         .nvram56        = 1,
 129 },
 130 [ds_1339] = {
 131         .alarm          = 1,
 132 },
 133 [ds_1340] = {
 134 },
 135 [ds_3231] = {
 136         .alarm          = 1,
 137 },
 138 [m41t00] = {
 139 },
 140 [rx_8025] = {
 141 }, };
 142
 143 static const struct i2c_device_id ds1307_id[] = {
 144         { "ds1307", ds_1307 },
 145         { "ds1337", ds_1337 },
 146         { "ds1338", ds_1338 },
 147         { "ds1339", ds_1339 },
 148         { "ds1388", ds_1388 },
 149         { "ds1340", ds_1340 },
 150         { "ds3231", ds_3231 },
 151         { "m41t00", m41t00 },
 152         { "rx8025", rx_8025 },
 153         { }
 154 };
 155 MODULE_DEVICE_TABLE(i2c, ds1307_id);
 156
 157 /*----------------------------------------------------------------------*/
 158
 159 #define BLOCK_DATA_MAX_TRIES 10
 160
 161 static s32 ds1307_read_block_data_once(const struct i2c_client *client,
 162                                        u8 command, u8 length, u8 *values)
 163 {
 164         s32 i, data;
 165
 166         for (i = 0; i < length; i++) {
 167                 data = i2c_smbus_read_byte_data(client, command + i);
 168                 if (data < 0)
 169                         return data;
 170                 values[i] = data;
 171         }
 172         return i;
 173 }
 174
 175 static s32 ds1307_read_block_data(const struct i2c_client *client, u8 command,
 176                                   u8 length, u8 *values)
 177 {
 178         u8 oldvalues[I2C_SMBUS_BLOCK_MAX];
 179         s32 ret;
 180         int tries = 0;
 181
 182         dev_dbg(&client->dev, "ds1307_read_block_data (length=%d)\n", length);
 183         ret = ds1307_read_block_data_once(client, command, length, values);
 184         if (ret < 0)
 185                 return ret;
 186         do {
 187                 if (++tries > BLOCK_DATA_MAX_TRIES) {
 188                         dev_err(&client->dev,
 189                                 "ds1307_read_block_data failed\n");
 190                         return -EIO;
 191                 }
 192                 memcpy(oldvalues, values, length);
 193                 ret = ds1307_read_block_data_once(client, command, length,
 194                                                   values);
 195                 if (ret < 0)
 196                         return ret;
 197         } while (memcmp(oldvalues, values, length));
 198         return length;
 199 }
 200
 201 static s32 ds1307_write_block_data(const struct i2c_client *client, u8 command,
 202                                    u8 length, const u8 *values)
 203 {
 204         u8 currvalues[I2C_SMBUS_BLOCK_MAX];
 205         int tries = 0;
 206
 207         dev_dbg(&client->dev, "ds1307_write_block_data (length=%d)\n", length);
 208         do {
 209                 s32 i, ret;
 210
 211                 if (++tries > BLOCK_DATA_MAX_TRIES) {
 212                         dev_err(&client->dev,
 213                                 "ds1307_write_block_data failed\n");
 214                         return -EIO;
 215                 }
 216                 for (i = 0; i < length; i++) {
 217                         ret = i2c_smbus_write_byte_data(client, command + i,
 218                                                         values[i]);
 219                         if (ret < 0)
 220                                 return ret;
 221                 }
 222                 ret = ds1307_read_block_data_once(client, command, length,
 223                                                   currvalues);
 224                 if (ret < 0)
 225                         return ret;
 226         } while (memcmp(currvalues, values, length));
 227         return length;
 228 }
 229
 230 /*----------------------------------------------------------------------*/
 231
 232 /*
 233  * The IRQ logic includes a "real" handler running in IRQ context just
 234  * long enough to schedule this workqueue entry.   We need a task context
 235  * to talk to the RTC, since I2C I/O calls require that; and disable the
 236  * IRQ until we clear its status on the chip, so that this handler can
 237  * work with any type of triggering (not just falling edge).
 238  *
 239  * The ds1337 and ds1339 both have two alarms, but we only use the first
 240  * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
 241  * signal; ds1339 chips have only one alarm signal.
 242  */
 243 static void ds1307_work(struct work_struct *work)
 244 {
 245         struct ds1307           *ds1307;
 246         struct i2c_client       *client;
 247         struct mutex            *lock;
 248         int                     stat, control;
 249
 250         ds1307 = container_of(work, struct ds1307, work);
 251         client = ds1307->client;
 252         lock = &ds1307->rtc->ops_lock;
 253
 254         mutex_lock(lock);
 255         stat = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
 256         if (stat < 0)
 257                 goto out;
 258
 259         if (stat & DS1337_BIT_A1I) {
 260                 stat &= ~DS1337_BIT_A1I;
 261                 i2c_smbus_write_byte_data(client, DS1337_REG_STATUS, stat);
 262
 263                 control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
 264                 if (control < 0)
 265                         goto out;
 266
 267                 control &= ~DS1337_BIT_A1IE;
 268                 i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, control);
 269
 270                 rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
 271         }
 272
 273 out:
 274         if (test_bit(HAS_ALARM, &ds1307->flags))
 275                 enable_irq(client->irq);
 276         mutex_unlock(lock);
 277 }
 278
 279 static irqreturn_t ds1307_irq(int irq, void *dev_id)
 280 {
 281         struct i2c_client       *client = dev_id;
 282         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 283
 284         disable_irq_nosync(irq);
 285         schedule_work(&ds1307->work);
 286         return IRQ_HANDLED;
 287 }
 288
 289 /*----------------------------------------------------------------------*/
 290
 291 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
 292 {
 293         struct ds1307   *ds1307 = dev_get_drvdata(dev);
 294         int             tmp;
 295
 296         /* read the RTC date and time registers all at once */
 297         tmp = ds1307->read_block_data(ds1307->client,
 298                 ds1307->offset, 7, ds1307->regs);
 299         if (tmp != 7) {
 300                 dev_err(dev, "%s error %d\n", "read", tmp);
 301                 return -EIO;
 302         }
 303
 304         dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
 305                         "read",
 306                         ds1307->regs[0], ds1307->regs[1],
 307                         ds1307->regs[2], ds1307->regs[3],
 308                         ds1307->regs[4], ds1307->regs[5],
 309                         ds1307->regs[6]);
 310
 311         t->tm_sec = bcd2bin(ds1307->regs[DS1307_REG_SECS] & 0x7f);
 312         t->tm_min = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f);
 313         tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
 314         t->tm_hour = bcd2bin(tmp);
 315         t->tm_wday = bcd2bin(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
 316         t->tm_mday = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
 317         tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
 318         t->tm_mon = bcd2bin(tmp) - 1;
 319
 320         /* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
 321         t->tm_year = bcd2bin(ds1307->regs[DS1307_REG_YEAR]) + 100;
 322
 323         dev_dbg(dev, "%s secs=%d, mins=%d, "
 324                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
 325                 "read", t->tm_sec, t->tm_min,
 326                 t->tm_hour, t->tm_mday,
 327                 t->tm_mon, t->tm_year, t->tm_wday);
 328
 329         /* initial clock setting can be undefined */
 330         return rtc_valid_tm(t);
 331 }
 332
 333 static int ds1307_set_time(struct device *dev, struct rtc_time *t)
 334 {
 335         struct ds1307   *ds1307 = dev_get_drvdata(dev);
 336         int             result;
 337         int             tmp;
 338         u8              *buf = ds1307->regs;
 339
 340         dev_dbg(dev, "%s secs=%d, mins=%d, "
 341                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
 342                 "write", t->tm_sec, t->tm_min,
 343                 t->tm_hour, t->tm_mday,
 344                 t->tm_mon, t->tm_year, t->tm_wday);
 345
 346         buf[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
 347         buf[DS1307_REG_MIN] = bin2bcd(t->tm_min);
 348         buf[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
 349         buf[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
 350         buf[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
 351         buf[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
 352
 353         /* assume 20YY not 19YY */
 354         tmp = t->tm_year - 100;
 355         buf[DS1307_REG_YEAR] = bin2bcd(tmp);
 356
 357         switch (ds1307->type) {
 358         case ds_1337:
 359         case ds_1339:
 360         case ds_3231:
 361                 buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
 362                 break;
 363         case ds_1340:
 364                 buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
 365                                 | DS1340_BIT_CENTURY;
 366                 break;
 367         default:
 368                 break;
 369         }
 370
 371         dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
 372                 "write", buf[0], buf[1], buf[2], buf[3],
 373                 buf[4], buf[5], buf[6]);
 374
 375         result = ds1307->write_block_data(ds1307->client,
 376                 ds1307->offset, 7, buf);
 377         if (result < 0) {
 378                 dev_err(dev, "%s error %d\n", "write", result);
 379                 return result;
 380         }
 381         return 0;
 382 }
 383
 384 static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 385 {
 386         struct i2c_client       *client = to_i2c_client(dev);
 387         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 388         int                     ret;
 389
 390         if (!test_bit(HAS_ALARM, &ds1307->flags))
 391                 return -EINVAL;
 392
 393         /* read all ALARM1, ALARM2, and status registers at once */
 394         ret = ds1307->read_block_data(client,
 395                         DS1339_REG_ALARM1_SECS, 9, ds1307->regs);
 396         if (ret != 9) {
 397                 dev_err(dev, "%s error %d\n", "alarm read", ret);
 398                 return -EIO;
 399         }
 400
 401         dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
 402                         "alarm read",
 403                         ds1307->regs[0], ds1307->regs[1],
 404                         ds1307->regs[2], ds1307->regs[3],
 405                         ds1307->regs[4], ds1307->regs[5],
 406                         ds1307->regs[6], ds1307->regs[7],
 407                         ds1307->regs[8]);
 408
 409         /* report alarm time (ALARM1); assume 24 hour and day-of-month modes,
 410          * and that all four fields are checked matches
 411          */
 412         t->time.tm_sec = bcd2bin(ds1307->regs[0] & 0x7f);
 413         t->time.tm_min = bcd2bin(ds1307->regs[1] & 0x7f);
 414         t->time.tm_hour = bcd2bin(ds1307->regs[2] & 0x3f);
 415         t->time.tm_mday = bcd2bin(ds1307->regs[3] & 0x3f);
 416         t->time.tm_mon = -1;
 417         t->time.tm_year = -1;
 418         t->time.tm_wday = -1;
 419         t->time.tm_yday = -1;
 420         t->time.tm_isdst = -1;
 421
 422         /* ... and status */
 423         t->enabled = !!(ds1307->regs[7] & DS1337_BIT_A1IE);
 424         t->pending = !!(ds1307->regs[8] & DS1337_BIT_A1I);
 425
 426         dev_dbg(dev, "%s secs=%d, mins=%d, "
 427                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
 428                 "alarm read", t->time.tm_sec, t->time.tm_min,
 429                 t->time.tm_hour, t->time.tm_mday,
 430                 t->enabled, t->pending);
 431
 432         return 0;
 433 }
 434
 435 static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 436 {
 437         struct i2c_client       *client = to_i2c_client(dev);
 438         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 439         unsigned char           *buf = ds1307->regs;
 440         u8                      control, status;
 441         int                     ret;
 442
 443         if (!test_bit(HAS_ALARM, &ds1307->flags))
 444                 return -EINVAL;
 445
 446         dev_dbg(dev, "%s secs=%d, mins=%d, "
 447                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
 448                 "alarm set", t->time.tm_sec, t->time.tm_min,
 449                 t->time.tm_hour, t->time.tm_mday,
 450                 t->enabled, t->pending);
 451
 452         /* read current status of both alarms and the chip */
 453         ret = ds1307->read_block_data(client,
 454                         DS1339_REG_ALARM1_SECS, 9, buf);
 455         if (ret != 9) {
 456                 dev_err(dev, "%s error %d\n", "alarm write", ret);
 457                 return -EIO;
 458         }
 459         control = ds1307->regs[7];
 460         status = ds1307->regs[8];
 461
 462         dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
 463                         "alarm set (old status)",
 464                         ds1307->regs[0], ds1307->regs[1],
 465                         ds1307->regs[2], ds1307->regs[3],
 466                         ds1307->regs[4], ds1307->regs[5],
 467                         ds1307->regs[6], control, status);
 468
 469         /* set ALARM1, using 24 hour and day-of-month modes */
 470         buf[0] = bin2bcd(t->time.tm_sec);
 471         buf[1] = bin2bcd(t->time.tm_min);
 472         buf[2] = bin2bcd(t->time.tm_hour);
 473         buf[3] = bin2bcd(t->time.tm_mday);
 474
 475         /* set ALARM2 to non-garbage */
 476         buf[4] = 0;
 477         buf[5] = 0;
 478         buf[6] = 0;
 479
 480         /* optionally enable ALARM1 */
 481         buf[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
 482         if (t->enabled) {
 483                 dev_dbg(dev, "alarm IRQ armed\n");
 484                 buf[7] |= DS1337_BIT_A1IE;      /* only ALARM1 is used */
 485         }
 486         buf[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
 487
 488         ret = ds1307->write_block_data(client,
 489                         DS1339_REG_ALARM1_SECS, 9, buf);
 490         if (ret < 0) {
 491                 dev_err(dev, "can't set alarm time\n");
 492                 return ret;
 493         }
 494
 495         return 0;
 496 }
 497
 498 static int ds1307_alarm_irq_enable(struct device *dev, unsigned int enabled)
 499 {
 500         struct i2c_client       *client = to_i2c_client(dev);
 501         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 502         int                     ret;
 503
 504         if (!test_bit(HAS_ALARM, &ds1307->flags))
 505                 return -ENOTTY;
 506
 507         ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
 508         if (ret < 0)
 509                 return ret;
 510
 511         if (enabled)
 512                 ret |= DS1337_BIT_A1IE;
 513         else
 514                 ret &= ~DS1337_BIT_A1IE;
 515
 516         ret = i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, ret);
 517         if (ret < 0)
 518                 return ret;
 519
 520         return 0;
 521 }
 522
 523 static const struct rtc_class_ops ds13xx_rtc_ops = {
 524         .read_time      = ds1307_get_time,
 525         .set_time       = ds1307_set_time,
 526         .read_alarm     = ds1337_read_alarm,
 527         .set_alarm      = ds1337_set_alarm,
 528         .alarm_irq_enable = ds1307_alarm_irq_enable,
 529 };
 530
 531 /*----------------------------------------------------------------------*/
 532
 533 #define NVRAM_SIZE      56
 534
 535 static ssize_t
 536 ds1307_nvram_read(struct file *filp, struct kobject *kobj,
 537                 struct bin_attribute *attr,
 538                 char *buf, loff_t off, size_t count)
 539 {
 540         struct i2c_client       *client;
 541         struct ds1307           *ds1307;
 542         int                     result;
 543
 544         client = kobj_to_i2c_client(kobj);
 545         ds1307 = i2c_get_clientdata(client);
 546
 547         if (unlikely(off >= NVRAM_SIZE))
 548                 return 0;
 549         if ((off + count) > NVRAM_SIZE)
 550                 count = NVRAM_SIZE - off;
 551         if (unlikely(!count))
 552                 return count;
 553
 554         result = ds1307->read_block_data(client, 8 + off, count, buf);
 555         if (result < 0)
 556                 dev_err(&client->dev, "%s error %d\n", "nvram read", result);
 557         return result;
 558 }
 559
 560 static ssize_t
 561 ds1307_nvram_write(struct file *filp, struct kobject *kobj,
 562                 struct bin_attribute *attr,
 563                 char *buf, loff_t off, size_t count)
 564 {
 565         struct i2c_client       *client;
 566         struct ds1307           *ds1307;
 567         int                     result;
 568
 569         client = kobj_to_i2c_client(kobj);
 570         ds1307 = i2c_get_clientdata(client);
 571
 572         if (unlikely(off >= NVRAM_SIZE))
 573                 return -EFBIG;
 574         if ((off + count) > NVRAM_SIZE)
 575                 count = NVRAM_SIZE - off;
 576         if (unlikely(!count))
 577                 return count;
 578
 579         result = ds1307->write_block_data(client, 8 + off, count, buf);
 580         if (result < 0) {
 581                 dev_err(&client->dev, "%s error %d\n", "nvram write", result);
 582                 return result;
 583         }
 584         return count;
 585 }
 586
 587 static struct bin_attribute nvram = {
 588         .attr = {
 589                 .name   = "nvram",
 590                 .mode   = S_IRUGO | S_IWUSR,
 591         },
 592
 593         .read   = ds1307_nvram_read,
 594         .write  = ds1307_nvram_write,
 595         .size   = NVRAM_SIZE,
 596 };
 597
 598 /*----------------------------------------------------------------------*/
 599
 600 static struct i2c_driver ds1307_driver;
 601
 602 static int __devinit ds1307_probe(struct i2c_client *client,
 603                                   const struct i2c_device_id *id)
 604 {
 605         struct ds1307           *ds1307;
 606         int                     err = -ENODEV;
 607         int                     tmp;
 608         const struct chip_desc  *chip = &chips[id->driver_data];
 609         struct i2c_adapter      *adapter = to_i2c_adapter(client->dev.parent);
 610         int                     want_irq = false;
 611         unsigned char           *buf;
 612         static const int        bbsqi_bitpos[] = {
 613                 [ds_1337] = 0,
 614                 [ds_1339] = DS1339_BIT_BBSQI,
 615                 [ds_3231] = DS3231_BIT_BBSQW,
 616         };
 617
 618         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)
 619             && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
 620                 return -EIO;
 621
 622         if (!(ds1307 = kzalloc(sizeof(struct ds1307), GFP_KERNEL)))
 623                 return -ENOMEM;
 624
 625         i2c_set_clientdata(client, ds1307);
 626
 627         ds1307->client  = client;
 628         ds1307->type    = id->driver_data;
 629         ds1307->offset  = 0;
 630
 631         buf = ds1307->regs;
 632         if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
 633                 ds1307->read_block_data = i2c_smbus_read_i2c_block_data;
 634                 ds1307->write_block_data = i2c_smbus_write_i2c_block_data;
 635         } else {
 636                 ds1307->read_block_data = ds1307_read_block_data;
 637                 ds1307->write_block_data = ds1307_write_block_data;
 638         }
 639
 640         switch (ds1307->type) {
 641         case ds_1337:
 642         case ds_1339:
 643         case ds_3231:
 644                 /* has IRQ? */
 645                 if (ds1307->client->irq > 0 && chip->alarm) {
 646                         INIT_WORK(&ds1307->work, ds1307_work);
 647                         want_irq = true;
 648                 }
 649                 /* get registers that the "rtc" read below won't read... */
 650                 tmp = ds1307->read_block_data(ds1307->client,
 651                                 DS1337_REG_CONTROL, 2, buf);
 652                 if (tmp != 2) {
 653                         pr_debug("read error %d\n", tmp);
 654                         err = -EIO;
 655                         goto exit_free;
 656                 }
 657
 658                 /* oscillator off?  turn it on, so clock can tick. */
 659                 if (ds1307->regs[0] & DS1337_BIT_nEOSC)
 660                         ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
 661
 662                 /* Using IRQ?  Disable the square wave and both alarms.
 663                  * For some variants, be sure alarms can trigger when we're
 664                  * running on Vbackup (BBSQI/BBSQW)
 665                  */
 666                 if (want_irq) {
 667                         ds1307->regs[0] |= DS1337_BIT_INTCN
 668                                         | bbsqi_bitpos[ds1307->type];
 669                         ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
 670                 }
 671
 672                 i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
 673                                                         ds1307->regs[0]);
 674
 675                 /* oscillator fault?  clear flag, and warn */
 676                 if (ds1307->regs[1] & DS1337_BIT_OSF) {
 677                         i2c_smbus_write_byte_data(client, DS1337_REG_STATUS,
 678                                 ds1307->regs[1] & ~DS1337_BIT_OSF);
 679                         dev_warn(&client->dev, "SET TIME!\n");
 680                 }
 681                 break;
 682
 683         case rx_8025:
 684                 tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
 685                                 RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
 686                 if (tmp != 2) {
 687                         pr_debug("read error %d\n", tmp);
 688                         err = -EIO;
 689                         goto exit_free;
 690                 }
 691
 692                 /* oscillator off?  turn it on, so clock can tick. */
 693                 if (!(ds1307->regs[1] & RX8025_BIT_XST)) {
 694                         ds1307->regs[1] |= RX8025_BIT_XST;
 695                         i2c_smbus_write_byte_data(client,
 696                                                   RX8025_REG_CTRL2 << 4 | 0x08,
 697                                                   ds1307->regs[1]);
 698                         dev_warn(&client->dev,
 699                                  "oscillator stop detected - SET TIME!\n");
 700                 }
 701
 702                 if (ds1307->regs[1] & RX8025_BIT_PON) {
 703                         ds1307->regs[1] &= ~RX8025_BIT_PON;
 704                         i2c_smbus_write_byte_data(client,
 705                                                   RX8025_REG_CTRL2 << 4 | 0x08,
 706                                                   ds1307->regs[1]);
 707                         dev_warn(&client->dev, "power-on detected\n");
 708                 }
 709
 710                 if (ds1307->regs[1] & RX8025_BIT_VDET) {
 711                         ds1307->regs[1] &= ~RX8025_BIT_VDET;
 712                         i2c_smbus_write_byte_data(client,
 713                                                   RX8025_REG_CTRL2 << 4 | 0x08,
 714                                                   ds1307->regs[1]);
 715                         dev_warn(&client->dev, "voltage drop detected\n");
 716                 }
 717
 718                 /* make sure we are running in 24hour mode */
 719                 if (!(ds1307->regs[0] & RX8025_BIT_2412)) {
 720                         u8 hour;
 721
 722                         /* switch to 24 hour mode */
 723                         i2c_smbus_write_byte_data(client,
 724                                                   RX8025_REG_CTRL1 << 4 | 0x08,
 725                                                   ds1307->regs[0] |
 726                                                   RX8025_BIT_2412);
 727
 728                         tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
 729                                         RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
 730                         if (tmp != 2) {
 731                                 pr_debug("read error %d\n", tmp);
 732                                 err = -EIO;
 733                                 goto exit_free;
 734                         }
 735
 736                         /* correct hour */
 737                         hour = bcd2bin(ds1307->regs[DS1307_REG_HOUR]);
 738                         if (hour == 12)
 739                                 hour = 0;
 740                         if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
 741                                 hour += 12;
 742
 743                         i2c_smbus_write_byte_data(client,
 744                                                   DS1307_REG_HOUR << 4 | 0x08,
 745                                                   hour);
 746                 }
 747                 break;
 748         case ds_1388:
 749                 ds1307->offset = 1; /* Seconds starts at 1 */
 750                 break;
 751         default:
 752                 break;
 753         }
 754
 755 read_rtc:
 756         /* read RTC registers */
 757         tmp = ds1307->read_block_data(ds1307->client, ds1307->offset, 8, buf);
 758         if (tmp != 8) {
 759                 pr_debug("read error %d\n", tmp);
 760                 err = -EIO;
 761                 goto exit_free;
 762         }
 763
 764         /* minimal sanity checking; some chips (like DS1340) don't
 765          * specify the extra bits as must-be-zero, but there are
 766          * still a few values that are clearly out-of-range.
 767          */
 768         tmp = ds1307->regs[DS1307_REG_SECS];
 769         switch (ds1307->type) {
 770         case ds_1307:
 771         case m41t00:
 772                 /* clock halted?  turn it on, so clock can tick. */
 773                 if (tmp & DS1307_BIT_CH) {
 774                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
 775                         dev_warn(&client->dev, "SET TIME!\n");
 776                         goto read_rtc;
 777                 }
 778                 break;
 779         case ds_1338:
 780                 /* clock halted?  turn it on, so clock can tick. */
 781                 if (tmp & DS1307_BIT_CH)
 782                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
 783
 784                 /* oscillator fault?  clear flag, and warn */
 785                 if (ds1307->regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
 786                         i2c_smbus_write_byte_data(client, DS1307_REG_CONTROL,
 787                                         ds1307->regs[DS1307_REG_CONTROL]
 788                                         & ~DS1338_BIT_OSF);
 789                         dev_warn(&client->dev, "SET TIME!\n");
 790                         goto read_rtc;
 791                 }
 792                 break;
 793         case ds_1340:
 794                 /* clock halted?  turn it on, so clock can tick. */
 795                 if (tmp & DS1340_BIT_nEOSC)
 796                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
 797
 798                 tmp = i2c_smbus_read_byte_data(client, DS1340_REG_FLAG);
 799                 if (tmp < 0) {
 800                         pr_debug("read error %d\n", tmp);
 801                         err = -EIO;
 802                         goto exit_free;
 803                 }
 804
 805                 /* oscillator fault?  clear flag, and warn */
 806                 if (tmp & DS1340_BIT_OSF) {
 807                         i2c_smbus_write_byte_data(client, DS1340_REG_FLAG, 0);
 808                         dev_warn(&client->dev, "SET TIME!\n");
 809                 }
 810                 break;
 811         case rx_8025:
 812         case ds_1337:
 813         case ds_1339:
 814         case ds_1388:
 815         case ds_3231:
 816                 break;
 817         }
 818
 819         tmp = ds1307->regs[DS1307_REG_HOUR];
 820         switch (ds1307->type) {
 821         case ds_1340:
 822         case m41t00:
 823                 /* NOTE: ignores century bits; fix before deploying
 824                  * systems that will run through year 2100.
 825                  */
 826                 break;
 827         case rx_8025:
 828                 break;
 829         default:
 830                 if (!(tmp & DS1307_BIT_12HR))
 831                         break;
 832
 833                 /* Be sure we're in 24 hour mode.  Multi-master systems
 834                  * take note...
 835                  */
 836                 tmp = bcd2bin(tmp & 0x1f);
 837                 if (tmp == 12)
 838                         tmp = 0;
 839                 if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
 840                         tmp += 12;
 841                 i2c_smbus_write_byte_data(client,
 842                                 ds1307->offset + DS1307_REG_HOUR,
 843                                 bin2bcd(tmp));
 844         }
 845
 846         ds1307->rtc = rtc_device_register(client->name, &client->dev,
 847                                 &ds13xx_rtc_ops, THIS_MODULE);
 848         if (IS_ERR(ds1307->rtc)) {
 849                 err = PTR_ERR(ds1307->rtc);
 850                 dev_err(&client->dev,
 851                         "unable to register the class device\n");
 852                 goto exit_free;
 853         }
 854
 855         if (want_irq) {
 856                 err = request_irq(client->irq, ds1307_irq, IRQF_SHARED,
 857                           ds1307->rtc->name, client);
 858                 if (err) {
 859                         dev_err(&client->dev,
 860                                 "unable to request IRQ!\n");
 861                         goto exit_irq;
 862                 }
 863
 864                 device_set_wakeup_capable(&client->dev, 1);
 865                 set_bit(HAS_ALARM, &ds1307->flags);
 866                 dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
 867         }
 868
 869         if (chip->nvram56) {
 870                 err = sysfs_create_bin_file(&client->dev.kobj, &nvram);
 871                 if (err == 0) {
 872                         set_bit(HAS_NVRAM, &ds1307->flags);
 873                         dev_info(&client->dev, "56 bytes nvram\n");
 874                 }
 875         }
 876
 877         return 0;
 878
 879 exit_irq:
 880         rtc_device_unregister(ds1307->rtc);
 881 exit_free:
 882         kfree(ds1307);
 883         return err;
 884 }
 885
 886 static int __devexit ds1307_remove(struct i2c_client *client)
 887 {
 888         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 889
 890         if (test_and_clear_bit(HAS_ALARM, &ds1307->flags)) {
 891                 free_irq(client->irq, client);
 892                 cancel_work_sync(&ds1307->work);
 893         }
 894
 895         if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags))
 896                 sysfs_remove_bin_file(&client->dev.kobj, &nvram);
 897
 898         rtc_device_unregister(ds1307->rtc);
 899         kfree(ds1307);
 900         return 0;
 901 }
 902
 903 static struct i2c_driver ds1307_driver = {
 904         .driver = {
 905                 .name   = "rtc-ds1307",
 906                 .owner  = THIS_MODULE,
 907         },
 908         .probe          = ds1307_probe,
 909         .remove         = __devexit_p(ds1307_remove),
 910         .id_table       = ds1307_id,
 911 };
 912
 913 static int __init ds1307_init(void)
 914 {
 915         return i2c_add_driver(&ds1307_driver);
 916 }
 917 module_init(ds1307_init);
 918
 919 static void __exit ds1307_exit(void)
 920 {
 921         i2c_del_driver(&ds1307_driver);
 922 }
 923 module_exit(ds1307_exit);
 924
 925 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
 926 MODULE_LICENSE("GPL");