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  *  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)(struct i2c_client *client, u8 command,
 110                                u8 length, u8 *values);
 111         s32 (*write_block_data)(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(struct i2c_client *client, u8 command,
 162                                   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(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(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() assumes that it is called
 271                  * from IRQ-disabled context.
 272                  */
 273                 local_irq_disable();
 274                 rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
 275                 local_irq_enable();
 276         }
 277
 278 out:
 279         if (test_bit(HAS_ALARM, &ds1307->flags))
 280                 enable_irq(client->irq);
 281         mutex_unlock(lock);
 282 }
 283
 284 static irqreturn_t ds1307_irq(int irq, void *dev_id)
 285 {
 286         struct i2c_client       *client = dev_id;
 287         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 288
 289         disable_irq_nosync(irq);
 290         schedule_work(&ds1307->work);
 291         return IRQ_HANDLED;
 292 }
 293
 294 /*----------------------------------------------------------------------*/
 295
 296 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
 297 {
 298         struct ds1307   *ds1307 = dev_get_drvdata(dev);
 299         int             tmp;
 300
 301         /* read the RTC date and time registers all at once */
 302         tmp = ds1307->read_block_data(ds1307->client,
 303                 ds1307->offset, 7, ds1307->regs);
 304         if (tmp != 7) {
 305                 dev_err(dev, "%s error %d\n", "read", tmp);
 306                 return -EIO;
 307         }
 308
 309         dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
 310                         "read",
 311                         ds1307->regs[0], ds1307->regs[1],
 312                         ds1307->regs[2], ds1307->regs[3],
 313                         ds1307->regs[4], ds1307->regs[5],
 314                         ds1307->regs[6]);
 315
 316         t->tm_sec = bcd2bin(ds1307->regs[DS1307_REG_SECS] & 0x7f);
 317         t->tm_min = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f);
 318         tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
 319         t->tm_hour = bcd2bin(tmp);
 320         t->tm_wday = bcd2bin(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
 321         t->tm_mday = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
 322         tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
 323         t->tm_mon = bcd2bin(tmp) - 1;
 324
 325         /* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
 326         t->tm_year = bcd2bin(ds1307->regs[DS1307_REG_YEAR]) + 100;
 327
 328         dev_dbg(dev, "%s secs=%d, mins=%d, "
 329                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
 330                 "read", t->tm_sec, t->tm_min,
 331                 t->tm_hour, t->tm_mday,
 332                 t->tm_mon, t->tm_year, t->tm_wday);
 333
 334         /* initial clock setting can be undefined */
 335         return rtc_valid_tm(t);
 336 }
 337
 338 static int ds1307_set_time(struct device *dev, struct rtc_time *t)
 339 {
 340         struct ds1307   *ds1307 = dev_get_drvdata(dev);
 341         int             result;
 342         int             tmp;
 343         u8              *buf = ds1307->regs;
 344
 345         dev_dbg(dev, "%s secs=%d, mins=%d, "
 346                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
 347                 "write", t->tm_sec, t->tm_min,
 348                 t->tm_hour, t->tm_mday,
 349                 t->tm_mon, t->tm_year, t->tm_wday);
 350
 351         buf[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
 352         buf[DS1307_REG_MIN] = bin2bcd(t->tm_min);
 353         buf[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
 354         buf[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
 355         buf[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
 356         buf[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
 357
 358         /* assume 20YY not 19YY */
 359         tmp = t->tm_year - 100;
 360         buf[DS1307_REG_YEAR] = bin2bcd(tmp);
 361
 362         switch (ds1307->type) {
 363         case ds_1337:
 364         case ds_1339:
 365         case ds_3231:
 366                 buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
 367                 break;
 368         case ds_1340:
 369                 buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
 370                                 | DS1340_BIT_CENTURY;
 371                 break;
 372         default:
 373                 break;
 374         }
 375
 376         dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
 377                 "write", buf[0], buf[1], buf[2], buf[3],
 378                 buf[4], buf[5], buf[6]);
 379
 380         result = ds1307->write_block_data(ds1307->client,
 381                 ds1307->offset, 7, buf);
 382         if (result < 0) {
 383                 dev_err(dev, "%s error %d\n", "write", result);
 384                 return result;
 385         }
 386         return 0;
 387 }
 388
 389 static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 390 {
 391         struct i2c_client       *client = to_i2c_client(dev);
 392         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 393         int                     ret;
 394
 395         if (!test_bit(HAS_ALARM, &ds1307->flags))
 396                 return -EINVAL;
 397
 398         /* read all ALARM1, ALARM2, and status registers at once */
 399         ret = ds1307->read_block_data(client,
 400                         DS1339_REG_ALARM1_SECS, 9, ds1307->regs);
 401         if (ret != 9) {
 402                 dev_err(dev, "%s error %d\n", "alarm read", ret);
 403                 return -EIO;
 404         }
 405
 406         dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
 407                         "alarm read",
 408                         ds1307->regs[0], ds1307->regs[1],
 409                         ds1307->regs[2], ds1307->regs[3],
 410                         ds1307->regs[4], ds1307->regs[5],
 411                         ds1307->regs[6], ds1307->regs[7],
 412                         ds1307->regs[8]);
 413
 414         /* report alarm time (ALARM1); assume 24 hour and day-of-month modes,
 415          * and that all four fields are checked matches
 416          */
 417         t->time.tm_sec = bcd2bin(ds1307->regs[0] & 0x7f);
 418         t->time.tm_min = bcd2bin(ds1307->regs[1] & 0x7f);
 419         t->time.tm_hour = bcd2bin(ds1307->regs[2] & 0x3f);
 420         t->time.tm_mday = bcd2bin(ds1307->regs[3] & 0x3f);
 421         t->time.tm_mon = -1;
 422         t->time.tm_year = -1;
 423         t->time.tm_wday = -1;
 424         t->time.tm_yday = -1;
 425         t->time.tm_isdst = -1;
 426
 427         /* ... and status */
 428         t->enabled = !!(ds1307->regs[7] & DS1337_BIT_A1IE);
 429         t->pending = !!(ds1307->regs[8] & DS1337_BIT_A1I);
 430
 431         dev_dbg(dev, "%s secs=%d, mins=%d, "
 432                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
 433                 "alarm read", t->time.tm_sec, t->time.tm_min,
 434                 t->time.tm_hour, t->time.tm_mday,
 435                 t->enabled, t->pending);
 436
 437         return 0;
 438 }
 439
 440 static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 441 {
 442         struct i2c_client       *client = to_i2c_client(dev);
 443         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 444         unsigned char           *buf = ds1307->regs;
 445         u8                      control, status;
 446         int                     ret;
 447
 448         if (!test_bit(HAS_ALARM, &ds1307->flags))
 449                 return -EINVAL;
 450
 451         dev_dbg(dev, "%s secs=%d, mins=%d, "
 452                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
 453                 "alarm set", t->time.tm_sec, t->time.tm_min,
 454                 t->time.tm_hour, t->time.tm_mday,
 455                 t->enabled, t->pending);
 456
 457         /* read current status of both alarms and the chip */
 458         ret = ds1307->read_block_data(client,
 459                         DS1339_REG_ALARM1_SECS, 9, buf);
 460         if (ret != 9) {
 461                 dev_err(dev, "%s error %d\n", "alarm write", ret);
 462                 return -EIO;
 463         }
 464         control = ds1307->regs[7];
 465         status = ds1307->regs[8];
 466
 467         dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
 468                         "alarm set (old status)",
 469                         ds1307->regs[0], ds1307->regs[1],
 470                         ds1307->regs[2], ds1307->regs[3],
 471                         ds1307->regs[4], ds1307->regs[5],
 472                         ds1307->regs[6], control, status);
 473
 474         /* set ALARM1, using 24 hour and day-of-month modes */
 475         buf[0] = bin2bcd(t->time.tm_sec);
 476         buf[1] = bin2bcd(t->time.tm_min);
 477         buf[2] = bin2bcd(t->time.tm_hour);
 478         buf[3] = bin2bcd(t->time.tm_mday);
 479
 480         /* set ALARM2 to non-garbage */
 481         buf[4] = 0;
 482         buf[5] = 0;
 483         buf[6] = 0;
 484
 485         /* optionally enable ALARM1 */
 486         buf[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
 487         if (t->enabled) {
 488                 dev_dbg(dev, "alarm IRQ armed\n");
 489                 buf[7] |= DS1337_BIT_A1IE;      /* only ALARM1 is used */
 490         }
 491         buf[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
 492
 493         ret = ds1307->write_block_data(client,
 494                         DS1339_REG_ALARM1_SECS, 9, buf);
 495         if (ret < 0) {
 496                 dev_err(dev, "can't set alarm time\n");
 497                 return ret;
 498         }
 499
 500         return 0;
 501 }
 502
 503 static int ds1307_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 504 {
 505         struct i2c_client       *client = to_i2c_client(dev);
 506         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 507         int                     ret;
 508
 509         switch (cmd) {
 510         case RTC_AIE_OFF:
 511                 if (!test_bit(HAS_ALARM, &ds1307->flags))
 512                         return -ENOTTY;
 513
 514                 ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
 515                 if (ret < 0)
 516                         return ret;
 517
 518                 ret &= ~DS1337_BIT_A1IE;
 519
 520                 ret = i2c_smbus_write_byte_data(client,
 521                                                 DS1337_REG_CONTROL, ret);
 522                 if (ret < 0)
 523                         return ret;
 524
 525                 break;
 526
 527         case RTC_AIE_ON:
 528                 if (!test_bit(HAS_ALARM, &ds1307->flags))
 529                         return -ENOTTY;
 530
 531                 ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
 532                 if (ret < 0)
 533                         return ret;
 534
 535                 ret |= DS1337_BIT_A1IE;
 536
 537                 ret = i2c_smbus_write_byte_data(client,
 538                                                 DS1337_REG_CONTROL, ret);
 539                 if (ret < 0)
 540                         return ret;
 541
 542                 break;
 543
 544         default:
 545                 return -ENOIOCTLCMD;
 546         }
 547
 548         return 0;
 549 }
 550
 551 static const struct rtc_class_ops ds13xx_rtc_ops = {
 552         .read_time      = ds1307_get_time,
 553         .set_time       = ds1307_set_time,
 554         .read_alarm     = ds1337_read_alarm,
 555         .set_alarm      = ds1337_set_alarm,
 556         .ioctl          = ds1307_ioctl,
 557 };
 558
 559 /*----------------------------------------------------------------------*/
 560
 561 #define NVRAM_SIZE      56
 562
 563 static ssize_t
 564 ds1307_nvram_read(struct kobject *kobj, struct bin_attribute *attr,
 565                 char *buf, loff_t off, size_t count)
 566 {
 567         struct i2c_client       *client;
 568         struct ds1307           *ds1307;
 569         int                     result;
 570
 571         client = kobj_to_i2c_client(kobj);
 572         ds1307 = i2c_get_clientdata(client);
 573
 574         if (unlikely(off >= NVRAM_SIZE))
 575                 return 0;
 576         if ((off + count) > NVRAM_SIZE)
 577                 count = NVRAM_SIZE - off;
 578         if (unlikely(!count))
 579                 return count;
 580
 581         result = ds1307->read_block_data(client, 8 + off, count, buf);
 582         if (result < 0)
 583                 dev_err(&client->dev, "%s error %d\n", "nvram read", result);
 584         return result;
 585 }
 586
 587 static ssize_t
 588 ds1307_nvram_write(struct kobject *kobj, struct bin_attribute *attr,
 589                 char *buf, loff_t off, size_t count)
 590 {
 591         struct i2c_client       *client;
 592         struct ds1307           *ds1307;
 593         int                     result;
 594
 595         client = kobj_to_i2c_client(kobj);
 596         ds1307 = i2c_get_clientdata(client);
 597
 598         if (unlikely(off >= NVRAM_SIZE))
 599                 return -EFBIG;
 600         if ((off + count) > NVRAM_SIZE)
 601                 count = NVRAM_SIZE - off;
 602         if (unlikely(!count))
 603                 return count;
 604
 605         result = ds1307->write_block_data(client, 8 + off, count, buf);
 606         if (result < 0) {
 607                 dev_err(&client->dev, "%s error %d\n", "nvram write", result);
 608                 return result;
 609         }
 610         return count;
 611 }
 612
 613 static struct bin_attribute nvram = {
 614         .attr = {
 615                 .name   = "nvram",
 616                 .mode   = S_IRUGO | S_IWUSR,
 617         },
 618
 619         .read   = ds1307_nvram_read,
 620         .write  = ds1307_nvram_write,
 621         .size   = NVRAM_SIZE,
 622 };
 623
 624 /*----------------------------------------------------------------------*/
 625
 626 static struct i2c_driver ds1307_driver;
 627
 628 static int __devinit ds1307_probe(struct i2c_client *client,
 629                                   const struct i2c_device_id *id)
 630 {
 631         struct ds1307           *ds1307;
 632         int                     err = -ENODEV;
 633         int                     tmp;
 634         const struct chip_desc  *chip = &chips[id->driver_data];
 635         struct i2c_adapter      *adapter = to_i2c_adapter(client->dev.parent);
 636         int                     want_irq = false;
 637         unsigned char           *buf;
 638         static const int        bbsqi_bitpos[] = {
 639                 [ds_1337] = 0,
 640                 [ds_1339] = DS1339_BIT_BBSQI,
 641                 [ds_3231] = DS3231_BIT_BBSQW,
 642         };
 643
 644         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)
 645             && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
 646                 return -EIO;
 647
 648         if (!(ds1307 = kzalloc(sizeof(struct ds1307), GFP_KERNEL)))
 649                 return -ENOMEM;
 650
 651         i2c_set_clientdata(client, ds1307);
 652
 653         ds1307->client  = client;
 654         ds1307->type    = id->driver_data;
 655         ds1307->offset  = 0;
 656
 657         buf = ds1307->regs;
 658         if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
 659                 ds1307->read_block_data = i2c_smbus_read_i2c_block_data;
 660                 ds1307->write_block_data = i2c_smbus_write_i2c_block_data;
 661         } else {
 662                 ds1307->read_block_data = ds1307_read_block_data;
 663                 ds1307->write_block_data = ds1307_write_block_data;
 664         }
 665
 666         switch (ds1307->type) {
 667         case ds_1337:
 668         case ds_1339:
 669         case ds_3231:
 670                 /* has IRQ? */
 671                 if (ds1307->client->irq > 0 && chip->alarm) {
 672                         INIT_WORK(&ds1307->work, ds1307_work);
 673                         want_irq = true;
 674                 }
 675                 /* get registers that the "rtc" read below won't read... */
 676                 tmp = ds1307->read_block_data(ds1307->client,
 677                                 DS1337_REG_CONTROL, 2, buf);
 678                 if (tmp != 2) {
 679                         pr_debug("read error %d\n", tmp);
 680                         err = -EIO;
 681                         goto exit_free;
 682                 }
 683
 684                 /* oscillator off?  turn it on, so clock can tick. */
 685                 if (ds1307->regs[0] & DS1337_BIT_nEOSC)
 686                         ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
 687
 688                 /* Using IRQ?  Disable the square wave and both alarms.
 689                  * For some variants, be sure alarms can trigger when we're
 690                  * running on Vbackup (BBSQI/BBSQW)
 691                  */
 692                 if (want_irq) {
 693                         ds1307->regs[0] |= DS1337_BIT_INTCN
 694                                         | bbsqi_bitpos[ds1307->type];
 695                         ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
 696                 }
 697
 698                 i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
 699                                                         ds1307->regs[0]);
 700
 701                 /* oscillator fault?  clear flag, and warn */
 702                 if (ds1307->regs[1] & DS1337_BIT_OSF) {
 703                         i2c_smbus_write_byte_data(client, DS1337_REG_STATUS,
 704                                 ds1307->regs[1] & ~DS1337_BIT_OSF);
 705                         dev_warn(&client->dev, "SET TIME!\n");
 706                 }
 707                 break;
 708
 709         case rx_8025:
 710                 tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
 711                                 RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
 712                 if (tmp != 2) {
 713                         pr_debug("read error %d\n", tmp);
 714                         err = -EIO;
 715                         goto exit_free;
 716                 }
 717
 718                 /* oscillator off?  turn it on, so clock can tick. */
 719                 if (!(ds1307->regs[1] & RX8025_BIT_XST)) {
 720                         ds1307->regs[1] |= RX8025_BIT_XST;
 721                         i2c_smbus_write_byte_data(client,
 722                                                   RX8025_REG_CTRL2 << 4 | 0x08,
 723                                                   ds1307->regs[1]);
 724                         dev_warn(&client->dev,
 725                                  "oscillator stop detected - SET TIME!\n");
 726                 }
 727
 728                 if (ds1307->regs[1] & RX8025_BIT_PON) {
 729                         ds1307->regs[1] &= ~RX8025_BIT_PON;
 730                         i2c_smbus_write_byte_data(client,
 731                                                   RX8025_REG_CTRL2 << 4 | 0x08,
 732                                                   ds1307->regs[1]);
 733                         dev_warn(&client->dev, "power-on detected\n");
 734                 }
 735
 736                 if (ds1307->regs[1] & RX8025_BIT_VDET) {
 737                         ds1307->regs[1] &= ~RX8025_BIT_VDET;
 738                         i2c_smbus_write_byte_data(client,
 739                                                   RX8025_REG_CTRL2 << 4 | 0x08,
 740                                                   ds1307->regs[1]);
 741                         dev_warn(&client->dev, "voltage drop detected\n");
 742                 }
 743
 744                 /* make sure we are running in 24hour mode */
 745                 if (!(ds1307->regs[0] & RX8025_BIT_2412)) {
 746                         u8 hour;
 747
 748                         /* switch to 24 hour mode */
 749                         i2c_smbus_write_byte_data(client,
 750                                                   RX8025_REG_CTRL1 << 4 | 0x08,
 751                                                   ds1307->regs[0] |
 752                                                   RX8025_BIT_2412);
 753
 754                         tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
 755                                         RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
 756                         if (tmp != 2) {
 757                                 pr_debug("read error %d\n", tmp);
 758                                 err = -EIO;
 759                                 goto exit_free;
 760                         }
 761
 762                         /* correct hour */
 763                         hour = bcd2bin(ds1307->regs[DS1307_REG_HOUR]);
 764                         if (hour == 12)
 765                                 hour = 0;
 766                         if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
 767                                 hour += 12;
 768
 769                         i2c_smbus_write_byte_data(client,
 770                                                   DS1307_REG_HOUR << 4 | 0x08,
 771                                                   hour);
 772                 }
 773                 break;
 774         case ds_1388:
 775                 ds1307->offset = 1; /* Seconds starts at 1 */
 776                 break;
 777         default:
 778                 break;
 779         }
 780
 781 read_rtc:
 782         /* read RTC registers */
 783         tmp = ds1307->read_block_data(ds1307->client, 0, 8, buf);
 784         if (tmp != 8) {
 785                 pr_debug("read error %d\n", tmp);
 786                 err = -EIO;
 787                 goto exit_free;
 788         }
 789
 790         /* minimal sanity checking; some chips (like DS1340) don't
 791          * specify the extra bits as must-be-zero, but there are
 792          * still a few values that are clearly out-of-range.
 793          */
 794         tmp = ds1307->regs[DS1307_REG_SECS];
 795         switch (ds1307->type) {
 796         case ds_1307:
 797         case m41t00:
 798                 /* clock halted?  turn it on, so clock can tick. */
 799                 if (tmp & DS1307_BIT_CH) {
 800                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
 801                         dev_warn(&client->dev, "SET TIME!\n");
 802                         goto read_rtc;
 803                 }
 804                 break;
 805         case ds_1338:
 806                 /* clock halted?  turn it on, so clock can tick. */
 807                 if (tmp & DS1307_BIT_CH)
 808                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
 809
 810                 /* oscillator fault?  clear flag, and warn */
 811                 if (ds1307->regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
 812                         i2c_smbus_write_byte_data(client, DS1307_REG_CONTROL,
 813                                         ds1307->regs[DS1307_REG_CONTROL]
 814                                         & ~DS1338_BIT_OSF);
 815                         dev_warn(&client->dev, "SET TIME!\n");
 816                         goto read_rtc;
 817                 }
 818                 break;
 819         case ds_1340:
 820                 /* clock halted?  turn it on, so clock can tick. */
 821                 if (tmp & DS1340_BIT_nEOSC)
 822                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
 823
 824                 tmp = i2c_smbus_read_byte_data(client, DS1340_REG_FLAG);
 825                 if (tmp < 0) {
 826                         pr_debug("read error %d\n", tmp);
 827                         err = -EIO;
 828                         goto exit_free;
 829                 }
 830
 831                 /* oscillator fault?  clear flag, and warn */
 832                 if (tmp & DS1340_BIT_OSF) {
 833                         i2c_smbus_write_byte_data(client, DS1340_REG_FLAG, 0);
 834                         dev_warn(&client->dev, "SET TIME!\n");
 835                 }
 836                 break;
 837         case rx_8025:
 838         case ds_1337:
 839         case ds_1339:
 840         case ds_1388:
 841         case ds_3231:
 842                 break;
 843         }
 844
 845         tmp = ds1307->regs[DS1307_REG_HOUR];
 846         switch (ds1307->type) {
 847         case ds_1340:
 848         case m41t00:
 849                 /* NOTE: ignores century bits; fix before deploying
 850                  * systems that will run through year 2100.
 851                  */
 852                 break;
 853         case rx_8025:
 854                 break;
 855         default:
 856                 if (!(tmp & DS1307_BIT_12HR))
 857                         break;
 858
 859                 /* Be sure we're in 24 hour mode.  Multi-master systems
 860                  * take note...
 861                  */
 862                 tmp = bcd2bin(tmp & 0x1f);
 863                 if (tmp == 12)
 864                         tmp = 0;
 865                 if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
 866                         tmp += 12;
 867                 i2c_smbus_write_byte_data(client,
 868                                 DS1307_REG_HOUR,
 869                                 bin2bcd(tmp));
 870         }
 871
 872         ds1307->rtc = rtc_device_register(client->name, &client->dev,
 873                                 &ds13xx_rtc_ops, THIS_MODULE);
 874         if (IS_ERR(ds1307->rtc)) {
 875                 err = PTR_ERR(ds1307->rtc);
 876                 dev_err(&client->dev,
 877                         "unable to register the class device\n");
 878                 goto exit_free;
 879         }
 880
 881         if (want_irq) {
 882                 err = request_irq(client->irq, ds1307_irq, 0,
 883                           ds1307->rtc->name, client);
 884                 if (err) {
 885                         dev_err(&client->dev,
 886                                 "unable to request IRQ!\n");
 887                         goto exit_irq;
 888                 }
 889                 set_bit(HAS_ALARM, &ds1307->flags);
 890                 dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
 891         }
 892
 893         if (chip->nvram56) {
 894                 err = sysfs_create_bin_file(&client->dev.kobj, &nvram);
 895                 if (err == 0) {
 896                         set_bit(HAS_NVRAM, &ds1307->flags);
 897                         dev_info(&client->dev, "56 bytes nvram\n");
 898                 }
 899         }
 900
 901         return 0;
 902
 903 exit_irq:
 904         if (ds1307->rtc)
 905                 rtc_device_unregister(ds1307->rtc);
 906 exit_free:
 907         kfree(ds1307);
 908         return err;
 909 }
 910
 911 static int __devexit ds1307_remove(struct i2c_client *client)
 912 {
 913         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 914
 915         if (test_and_clear_bit(HAS_ALARM, &ds1307->flags)) {
 916                 free_irq(client->irq, client);
 917                 cancel_work_sync(&ds1307->work);
 918         }
 919
 920         if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags))
 921                 sysfs_remove_bin_file(&client->dev.kobj, &nvram);
 922
 923         rtc_device_unregister(ds1307->rtc);
 924         kfree(ds1307);
 925         return 0;
 926 }
 927
 928 static struct i2c_driver ds1307_driver = {
 929         .driver = {
 930                 .name   = "rtc-ds1307",
 931                 .owner  = THIS_MODULE,
 932         },
 933         .probe          = ds1307_probe,
 934         .remove         = __devexit_p(ds1307_remove),
 935         .id_table       = ds1307_id,
 936 };
 937
 938 static int __init ds1307_init(void)
 939 {
 940         return i2c_add_driver(&ds1307_driver);
 941 }
 942 module_init(ds1307_init);
 943
 944 static void __exit ds1307_exit(void)
 945 {
 946         i2c_del_driver(&ds1307_driver);
 947 }
 948 module_exit(ds1307_exit);
 949
 950 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
 951 MODULE_LICENSE("GPL");