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         m41t00,
  35         rx_8025,
  36         // rs5c372 too?  different address...
  37 };
  38
  39
  40 /* RTC registers don't differ much, except for the century flag */
  41 #define DS1307_REG_SECS         0x00    /* 00-59 */
  42 #       define DS1307_BIT_CH            0x80
  43 #       define DS1340_BIT_nEOSC         0x80
  44 #define DS1307_REG_MIN          0x01    /* 00-59 */
  45 #define DS1307_REG_HOUR         0x02    /* 00-23, or 1-12{am,pm} */
  46 #       define DS1307_BIT_12HR          0x40    /* in REG_HOUR */
  47 #       define DS1307_BIT_PM            0x20    /* in REG_HOUR */
  48 #       define DS1340_BIT_CENTURY_EN    0x80    /* in REG_HOUR */
  49 #       define DS1340_BIT_CENTURY       0x40    /* in REG_HOUR */
  50 #define DS1307_REG_WDAY         0x03    /* 01-07 */
  51 #define DS1307_REG_MDAY         0x04    /* 01-31 */
  52 #define DS1307_REG_MONTH        0x05    /* 01-12 */
  53 #       define DS1337_BIT_CENTURY       0x80    /* in REG_MONTH */
  54 #define DS1307_REG_YEAR         0x06    /* 00-99 */
  55
  56 /* Other registers (control, status, alarms, trickle charge, NVRAM, etc)
  57  * start at 7, and they differ a LOT. Only control and status matter for
  58  * basic RTC date and time functionality; be careful using them.
  59  */
  60 #define DS1307_REG_CONTROL      0x07            /* or ds1338 */
  61 #       define DS1307_BIT_OUT           0x80
  62 #       define DS1338_BIT_OSF           0x20
  63 #       define DS1307_BIT_SQWE          0x10
  64 #       define DS1307_BIT_RS1           0x02
  65 #       define DS1307_BIT_RS0           0x01
  66 #define DS1337_REG_CONTROL      0x0e
  67 #       define DS1337_BIT_nEOSC         0x80
  68 #       define DS1339_BIT_BBSQI         0x20
  69 #       define DS1337_BIT_RS2           0x10
  70 #       define DS1337_BIT_RS1           0x08
  71 #       define DS1337_BIT_INTCN         0x04
  72 #       define DS1337_BIT_A2IE          0x02
  73 #       define DS1337_BIT_A1IE          0x01
  74 #define DS1340_REG_CONTROL      0x07
  75 #       define DS1340_BIT_OUT           0x80
  76 #       define DS1340_BIT_FT            0x40
  77 #       define DS1340_BIT_CALIB_SIGN    0x20
  78 #       define DS1340_M_CALIBRATION     0x1f
  79 #define DS1340_REG_FLAG         0x09
  80 #       define DS1340_BIT_OSF           0x80
  81 #define DS1337_REG_STATUS       0x0f
  82 #       define DS1337_BIT_OSF           0x80
  83 #       define DS1337_BIT_A2I           0x02
  84 #       define DS1337_BIT_A1I           0x01
  85 #define DS1339_REG_ALARM1_SECS  0x07
  86 #define DS1339_REG_TRICKLE      0x10
  87
  88 #define RX8025_REG_CTRL1        0x0e
  89 #       define RX8025_BIT_2412          0x20
  90 #define RX8025_REG_CTRL2        0x0f
  91 #       define RX8025_BIT_PON           0x10
  92 #       define RX8025_BIT_VDET          0x40
  93 #       define RX8025_BIT_XST           0x20
  94
  95
  96 struct ds1307 {
  97         u8                      regs[11];
  98         enum ds_type            type;
  99         unsigned long           flags;
 100 #define HAS_NVRAM       0               /* bit 0 == sysfs file active */
 101 #define HAS_ALARM       1               /* bit 1 == irq claimed */
 102         struct i2c_client       *client;
 103         struct rtc_device       *rtc;
 104         struct work_struct      work;
 105         s32 (*read_block_data)(struct i2c_client *client, u8 command,
 106                                u8 length, u8 *values);
 107         s32 (*write_block_data)(struct i2c_client *client, u8 command,
 108                                 u8 length, const u8 *values);
 109 };
 110
 111 struct chip_desc {
 112         unsigned                nvram56:1;
 113         unsigned                alarm:1;
 114 };
 115
 116 static const struct chip_desc chips[] = {
 117 [ds_1307] = {
 118         .nvram56        = 1,
 119 },
 120 [ds_1337] = {
 121         .alarm          = 1,
 122 },
 123 [ds_1338] = {
 124         .nvram56        = 1,
 125 },
 126 [ds_1339] = {
 127         .alarm          = 1,
 128 },
 129 [ds_1340] = {
 130 },
 131 [m41t00] = {
 132 },
 133 [rx_8025] = {
 134 }, };
 135
 136 static const struct i2c_device_id ds1307_id[] = {
 137         { "ds1307", ds_1307 },
 138         { "ds1337", ds_1337 },
 139         { "ds1338", ds_1338 },
 140         { "ds1339", ds_1339 },
 141         { "ds1340", ds_1340 },
 142         { "m41t00", m41t00 },
 143         { "rx8025", rx_8025 },
 144         { }
 145 };
 146 MODULE_DEVICE_TABLE(i2c, ds1307_id);
 147
 148 /*----------------------------------------------------------------------*/
 149
 150 #define BLOCK_DATA_MAX_TRIES 10
 151
 152 static s32 ds1307_read_block_data_once(struct i2c_client *client, u8 command,
 153                                   u8 length, u8 *values)
 154 {
 155         s32 i, data;
 156
 157         for (i = 0; i < length; i++) {
 158                 data = i2c_smbus_read_byte_data(client, command + i);
 159                 if (data < 0)
 160                         return data;
 161                 values[i] = data;
 162         }
 163         return i;
 164 }
 165
 166 static s32 ds1307_read_block_data(struct i2c_client *client, u8 command,
 167                                   u8 length, u8 *values)
 168 {
 169         u8 oldvalues[I2C_SMBUS_BLOCK_MAX];
 170         s32 ret;
 171         int tries = 0;
 172
 173         dev_dbg(&client->dev, "ds1307_read_block_data (length=%d)\n", length);
 174         ret = ds1307_read_block_data_once(client, command, length, values);
 175         if (ret < 0)
 176                 return ret;
 177         do {
 178                 if (++tries > BLOCK_DATA_MAX_TRIES) {
 179                         dev_err(&client->dev,
 180                                 "ds1307_read_block_data failed\n");
 181                         return -EIO;
 182                 }
 183                 memcpy(oldvalues, values, length);
 184                 ret = ds1307_read_block_data_once(client, command, length,
 185                                                   values);
 186                 if (ret < 0)
 187                         return ret;
 188         } while (memcmp(oldvalues, values, length));
 189         return length;
 190 }
 191
 192 static s32 ds1307_write_block_data(struct i2c_client *client, u8 command,
 193                                    u8 length, const u8 *values)
 194 {
 195         u8 currvalues[I2C_SMBUS_BLOCK_MAX];
 196         int tries = 0;
 197
 198         dev_dbg(&client->dev, "ds1307_write_block_data (length=%d)\n", length);
 199         do {
 200                 s32 i, ret;
 201
 202                 if (++tries > BLOCK_DATA_MAX_TRIES) {
 203                         dev_err(&client->dev,
 204                                 "ds1307_write_block_data failed\n");
 205                         return -EIO;
 206                 }
 207                 for (i = 0; i < length; i++) {
 208                         ret = i2c_smbus_write_byte_data(client, command + i,
 209                                                         values[i]);
 210                         if (ret < 0)
 211                                 return ret;
 212                 }
 213                 ret = ds1307_read_block_data_once(client, command, length,
 214                                                   currvalues);
 215                 if (ret < 0)
 216                         return ret;
 217         } while (memcmp(currvalues, values, length));
 218         return length;
 219 }
 220
 221 /*----------------------------------------------------------------------*/
 222
 223 /*
 224  * The IRQ logic includes a "real" handler running in IRQ context just
 225  * long enough to schedule this workqueue entry.   We need a task context
 226  * to talk to the RTC, since I2C I/O calls require that; and disable the
 227  * IRQ until we clear its status on the chip, so that this handler can
 228  * work with any type of triggering (not just falling edge).
 229  *
 230  * The ds1337 and ds1339 both have two alarms, but we only use the first
 231  * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
 232  * signal; ds1339 chips have only one alarm signal.
 233  */
 234 static void ds1307_work(struct work_struct *work)
 235 {
 236         struct ds1307           *ds1307;
 237         struct i2c_client       *client;
 238         struct mutex            *lock;
 239         int                     stat, control;
 240
 241         ds1307 = container_of(work, struct ds1307, work);
 242         client = ds1307->client;
 243         lock = &ds1307->rtc->ops_lock;
 244
 245         mutex_lock(lock);
 246         stat = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
 247         if (stat < 0)
 248                 goto out;
 249
 250         if (stat & DS1337_BIT_A1I) {
 251                 stat &= ~DS1337_BIT_A1I;
 252                 i2c_smbus_write_byte_data(client, DS1337_REG_STATUS, stat);
 253
 254                 control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
 255                 if (control < 0)
 256                         goto out;
 257
 258                 control &= ~DS1337_BIT_A1IE;
 259                 i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, control);
 260
 261                 /* rtc_update_irq() assumes that it is called
 262                  * from IRQ-disabled context.
 263                  */
 264                 local_irq_disable();
 265                 rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
 266                 local_irq_enable();
 267         }
 268
 269 out:
 270         if (test_bit(HAS_ALARM, &ds1307->flags))
 271                 enable_irq(client->irq);
 272         mutex_unlock(lock);
 273 }
 274
 275 static irqreturn_t ds1307_irq(int irq, void *dev_id)
 276 {
 277         struct i2c_client       *client = dev_id;
 278         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 279
 280         disable_irq_nosync(irq);
 281         schedule_work(&ds1307->work);
 282         return IRQ_HANDLED;
 283 }
 284
 285 /*----------------------------------------------------------------------*/
 286
 287 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
 288 {
 289         struct ds1307   *ds1307 = dev_get_drvdata(dev);
 290         int             tmp;
 291
 292         /* read the RTC date and time registers all at once */
 293         tmp = ds1307->read_block_data(ds1307->client,
 294                 DS1307_REG_SECS, 7, ds1307->regs);
 295         if (tmp != 7) {
 296                 dev_err(dev, "%s error %d\n", "read", tmp);
 297                 return -EIO;
 298         }
 299
 300         dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
 301                         "read",
 302                         ds1307->regs[0], ds1307->regs[1],
 303                         ds1307->regs[2], ds1307->regs[3],
 304                         ds1307->regs[4], ds1307->regs[5],
 305                         ds1307->regs[6]);
 306
 307         t->tm_sec = bcd2bin(ds1307->regs[DS1307_REG_SECS] & 0x7f);
 308         t->tm_min = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f);
 309         tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
 310         t->tm_hour = bcd2bin(tmp);
 311         t->tm_wday = bcd2bin(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
 312         t->tm_mday = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
 313         tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
 314         t->tm_mon = bcd2bin(tmp) - 1;
 315
 316         /* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
 317         t->tm_year = bcd2bin(ds1307->regs[DS1307_REG_YEAR]) + 100;
 318
 319         dev_dbg(dev, "%s secs=%d, mins=%d, "
 320                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
 321                 "read", t->tm_sec, t->tm_min,
 322                 t->tm_hour, t->tm_mday,
 323                 t->tm_mon, t->tm_year, t->tm_wday);
 324
 325         /* initial clock setting can be undefined */
 326         return rtc_valid_tm(t);
 327 }
 328
 329 static int ds1307_set_time(struct device *dev, struct rtc_time *t)
 330 {
 331         struct ds1307   *ds1307 = dev_get_drvdata(dev);
 332         int             result;
 333         int             tmp;
 334         u8              *buf = ds1307->regs;
 335
 336         dev_dbg(dev, "%s secs=%d, mins=%d, "
 337                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
 338                 "write", t->tm_sec, t->tm_min,
 339                 t->tm_hour, t->tm_mday,
 340                 t->tm_mon, t->tm_year, t->tm_wday);
 341
 342         buf[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
 343         buf[DS1307_REG_MIN] = bin2bcd(t->tm_min);
 344         buf[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
 345         buf[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
 346         buf[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
 347         buf[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
 348
 349         /* assume 20YY not 19YY */
 350         tmp = t->tm_year - 100;
 351         buf[DS1307_REG_YEAR] = bin2bcd(tmp);
 352
 353         switch (ds1307->type) {
 354         case ds_1337:
 355         case ds_1339:
 356                 buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
 357                 break;
 358         case ds_1340:
 359                 buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
 360                                 | DS1340_BIT_CENTURY;
 361                 break;
 362         default:
 363                 break;
 364         }
 365
 366         dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
 367                 "write", buf[0], buf[1], buf[2], buf[3],
 368                 buf[4], buf[5], buf[6]);
 369
 370         result = ds1307->write_block_data(ds1307->client, 0, 7, buf);
 371         if (result < 0) {
 372                 dev_err(dev, "%s error %d\n", "write", result);
 373                 return result;
 374         }
 375         return 0;
 376 }
 377
 378 static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 379 {
 380         struct i2c_client       *client = to_i2c_client(dev);
 381         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 382         int                     ret;
 383
 384         if (!test_bit(HAS_ALARM, &ds1307->flags))
 385                 return -EINVAL;
 386
 387         /* read all ALARM1, ALARM2, and status registers at once */
 388         ret = ds1307->read_block_data(client,
 389                         DS1339_REG_ALARM1_SECS, 9, ds1307->regs);
 390         if (ret != 9) {
 391                 dev_err(dev, "%s error %d\n", "alarm read", ret);
 392                 return -EIO;
 393         }
 394
 395         dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
 396                         "alarm read",
 397                         ds1307->regs[0], ds1307->regs[1],
 398                         ds1307->regs[2], ds1307->regs[3],
 399                         ds1307->regs[4], ds1307->regs[5],
 400                         ds1307->regs[6], ds1307->regs[7],
 401                         ds1307->regs[8]);
 402
 403         /* report alarm time (ALARM1); assume 24 hour and day-of-month modes,
 404          * and that all four fields are checked matches
 405          */
 406         t->time.tm_sec = bcd2bin(ds1307->regs[0] & 0x7f);
 407         t->time.tm_min = bcd2bin(ds1307->regs[1] & 0x7f);
 408         t->time.tm_hour = bcd2bin(ds1307->regs[2] & 0x3f);
 409         t->time.tm_mday = bcd2bin(ds1307->regs[3] & 0x3f);
 410         t->time.tm_mon = -1;
 411         t->time.tm_year = -1;
 412         t->time.tm_wday = -1;
 413         t->time.tm_yday = -1;
 414         t->time.tm_isdst = -1;
 415
 416         /* ... and status */
 417         t->enabled = !!(ds1307->regs[7] & DS1337_BIT_A1IE);
 418         t->pending = !!(ds1307->regs[8] & DS1337_BIT_A1I);
 419
 420         dev_dbg(dev, "%s secs=%d, mins=%d, "
 421                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
 422                 "alarm read", t->time.tm_sec, t->time.tm_min,
 423                 t->time.tm_hour, t->time.tm_mday,
 424                 t->enabled, t->pending);
 425
 426         return 0;
 427 }
 428
 429 static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 430 {
 431         struct i2c_client       *client = to_i2c_client(dev);
 432         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 433         unsigned char           *buf = ds1307->regs;
 434         u8                      control, status;
 435         int                     ret;
 436
 437         if (!test_bit(HAS_ALARM, &ds1307->flags))
 438                 return -EINVAL;
 439
 440         dev_dbg(dev, "%s secs=%d, mins=%d, "
 441                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
 442                 "alarm set", t->time.tm_sec, t->time.tm_min,
 443                 t->time.tm_hour, t->time.tm_mday,
 444                 t->enabled, t->pending);
 445
 446         /* read current status of both alarms and the chip */
 447         ret = ds1307->read_block_data(client,
 448                         DS1339_REG_ALARM1_SECS, 9, buf);
 449         if (ret != 9) {
 450                 dev_err(dev, "%s error %d\n", "alarm write", ret);
 451                 return -EIO;
 452         }
 453         control = ds1307->regs[7];
 454         status = ds1307->regs[8];
 455
 456         dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
 457                         "alarm set (old status)",
 458                         ds1307->regs[0], ds1307->regs[1],
 459                         ds1307->regs[2], ds1307->regs[3],
 460                         ds1307->regs[4], ds1307->regs[5],
 461                         ds1307->regs[6], control, status);
 462
 463         /* set ALARM1, using 24 hour and day-of-month modes */
 464         buf[0] = bin2bcd(t->time.tm_sec);
 465         buf[1] = bin2bcd(t->time.tm_min);
 466         buf[2] = bin2bcd(t->time.tm_hour);
 467         buf[3] = bin2bcd(t->time.tm_mday);
 468
 469         /* set ALARM2 to non-garbage */
 470         buf[4] = 0;
 471         buf[5] = 0;
 472         buf[6] = 0;
 473
 474         /* optionally enable ALARM1 */
 475         buf[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
 476         if (t->enabled) {
 477                 dev_dbg(dev, "alarm IRQ armed\n");
 478                 buf[7] |= DS1337_BIT_A1IE;      /* only ALARM1 is used */
 479         }
 480         buf[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
 481
 482         ret = ds1307->write_block_data(client,
 483                         DS1339_REG_ALARM1_SECS, 9, buf);
 484         if (ret < 0) {
 485                 dev_err(dev, "can't set alarm time\n");
 486                 return ret;
 487         }
 488
 489         return 0;
 490 }
 491
 492 static int ds1307_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 493 {
 494         struct i2c_client       *client = to_i2c_client(dev);
 495         struct ds1307           *ds1307 = i2c_get_clientdata(client);
 496         int                     ret;
 497
 498         switch (cmd) {
 499         case RTC_AIE_OFF:
 500                 if (!test_bit(HAS_ALARM, &ds1307->flags))
 501                         return -ENOTTY;
 502
 503                 ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
 504                 if (ret < 0)
 505                         return ret;
 506
 507                 ret &= ~DS1337_BIT_A1IE;
 508
 509                 ret = i2c_smbus_write_byte_data(client,
 510                                                 DS1337_REG_CONTROL, ret);
 511                 if (ret < 0)
 512                         return ret;
 513
 514                 break;
 515
 516         case RTC_AIE_ON:
 517                 if (!test_bit(HAS_ALARM, &ds1307->flags))
 518                         return -ENOTTY;
 519
 520                 ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
 521                 if (ret < 0)
 522                         return ret;
 523
 524                 ret |= DS1337_BIT_A1IE;
 525
 526                 ret = i2c_smbus_write_byte_data(client,
 527                                                 DS1337_REG_CONTROL, ret);
 528                 if (ret < 0)
 529                         return ret;
 530
 531                 break;
 532
 533         default:
 534                 return -ENOIOCTLCMD;
 535         }
 536
 537         return 0;
 538 }
 539
 540 static const struct rtc_class_ops ds13xx_rtc_ops = {
 541         .read_time      = ds1307_get_time,
 542         .set_time       = ds1307_set_time,
 543         .read_alarm     = ds1337_read_alarm,
 544         .set_alarm      = ds1337_set_alarm,
 545         .ioctl          = ds1307_ioctl,
 546 };
 547
 548 /*----------------------------------------------------------------------*/
 549
 550 #define NVRAM_SIZE      56
 551
 552 static ssize_t
 553 ds1307_nvram_read(struct kobject *kobj, struct bin_attribute *attr,
 554                 char *buf, loff_t off, size_t count)
 555 {
 556         struct i2c_client       *client;
 557         struct ds1307           *ds1307;
 558         int                     result;
 559
 560         client = kobj_to_i2c_client(kobj);
 561         ds1307 = i2c_get_clientdata(client);
 562
 563         if (unlikely(off >= NVRAM_SIZE))
 564                 return 0;
 565         if ((off + count) > NVRAM_SIZE)
 566                 count = NVRAM_SIZE - off;
 567         if (unlikely(!count))
 568                 return count;
 569
 570         result = ds1307->read_block_data(client, 8 + off, count, buf);
 571         if (result < 0)
 572                 dev_err(&client->dev, "%s error %d\n", "nvram read", result);
 573         return result;
 574 }
 575
 576 static ssize_t
 577 ds1307_nvram_write(struct kobject *kobj, struct bin_attribute *attr,
 578                 char *buf, loff_t off, size_t count)
 579 {
 580         struct i2c_client       *client;
 581         struct ds1307           *ds1307;
 582         int                     result;
 583
 584         client = kobj_to_i2c_client(kobj);
 585         ds1307 = i2c_get_clientdata(client);
 586
 587         if (unlikely(off >= NVRAM_SIZE))
 588                 return -EFBIG;
 589         if ((off + count) > NVRAM_SIZE)
 590                 count = NVRAM_SIZE - off;
 591         if (unlikely(!count))
 592                 return count;
 593
 594         result = ds1307->write_block_data(client, 8 + off, count, buf);
 595         if (result < 0) {
 596                 dev_err(&client->dev, "%s error %d\n", "nvram write", result);
 597                 return result;
 598         }
 599         return count;
 600 }
 601
 602 static struct bin_attribute nvram = {
 603         .attr = {
 604                 .name   = "nvram",
 605                 .mode   = S_IRUGO | S_IWUSR,
 606         },
 607
 608         .read   = ds1307_nvram_read,
 609         .write  = ds1307_nvram_write,
 610         .size   = NVRAM_SIZE,
 611 };
 612
 613 /*----------------------------------------------------------------------*/
 614
 615 static struct i2c_driver ds1307_driver;
 616
 617 static int __devinit ds1307_probe(struct i2c_client *client,
 618                                   const struct i2c_device_id *id)
 619 {
 620         struct ds1307           *ds1307;
 621         int                     err = -ENODEV;
 622         int                     tmp;
 623         const struct chip_desc  *chip = &chips[id->driver_data];
 624         struct i2c_adapter      *adapter = to_i2c_adapter(client->dev.parent);
 625         int                     want_irq = false;
 626         unsigned char           *buf;
 627
 628         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)
 629             && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
 630                 return -EIO;
 631
 632         if (!(ds1307 = kzalloc(sizeof(struct ds1307), GFP_KERNEL)))
 633                 return -ENOMEM;
 634
 635         ds1307->client = client;
 636         i2c_set_clientdata(client, ds1307);
 637         ds1307->type = id->driver_data;
 638         buf = ds1307->regs;
 639         if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
 640                 ds1307->read_block_data = i2c_smbus_read_i2c_block_data;
 641                 ds1307->write_block_data = i2c_smbus_write_i2c_block_data;
 642         } else {
 643                 ds1307->read_block_data = ds1307_read_block_data;
 644                 ds1307->write_block_data = ds1307_write_block_data;
 645         }
 646
 647         switch (ds1307->type) {
 648         case ds_1337:
 649         case ds_1339:
 650                 /* has IRQ? */
 651                 if (ds1307->client->irq > 0 && chip->alarm) {
 652                         INIT_WORK(&ds1307->work, ds1307_work);
 653                         want_irq = true;
 654                 }
 655                 /* get registers that the "rtc" read below won't read... */
 656                 tmp = ds1307->read_block_data(ds1307->client,
 657                                 DS1337_REG_CONTROL, 2, buf);
 658                 if (tmp != 2) {
 659                         pr_debug("read error %d\n", tmp);
 660                         err = -EIO;
 661                         goto exit_free;
 662                 }
 663
 664                 /* oscillator off?  turn it on, so clock can tick. */
 665                 if (ds1307->regs[0] & DS1337_BIT_nEOSC)
 666                         ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
 667
 668                 /* Using IRQ?  Disable the square wave and both alarms.
 669                  * For ds1339, be sure alarms can trigger when we're
 670                  * running on Vbackup (BBSQI); we assume ds1337 will
 671                  * ignore that bit
 672                  */
 673                 if (want_irq) {
 674                         ds1307->regs[0] |= DS1337_BIT_INTCN | DS1339_BIT_BBSQI;
 675                         ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
 676                 }
 677
 678                 i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
 679                                                         ds1307->regs[0]);
 680
 681                 /* oscillator fault?  clear flag, and warn */
 682                 if (ds1307->regs[1] & DS1337_BIT_OSF) {
 683                         i2c_smbus_write_byte_data(client, DS1337_REG_STATUS,
 684                                 ds1307->regs[1] & ~DS1337_BIT_OSF);
 685                         dev_warn(&client->dev, "SET TIME!\n");
 686                 }
 687                 break;
 688
 689         case rx_8025:
 690                 tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
 691                                 RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
 692                 if (tmp != 2) {
 693                         pr_debug("read error %d\n", tmp);
 694                         err = -EIO;
 695                         goto exit_free;
 696                 }
 697
 698                 /* oscillator off?  turn it on, so clock can tick. */
 699                 if (!(ds1307->regs[1] & RX8025_BIT_XST)) {
 700                         ds1307->regs[1] |= RX8025_BIT_XST;
 701                         i2c_smbus_write_byte_data(client,
 702                                                   RX8025_REG_CTRL2 << 4 | 0x08,
 703                                                   ds1307->regs[1]);
 704                         dev_warn(&client->dev,
 705                                  "oscillator stop detected - SET TIME!\n");
 706                 }
 707
 708                 if (ds1307->regs[1] & RX8025_BIT_PON) {
 709                         ds1307->regs[1] &= ~RX8025_BIT_PON;
 710                         i2c_smbus_write_byte_data(client,
 711                                                   RX8025_REG_CTRL2 << 4 | 0x08,
 712                                                   ds1307->regs[1]);
 713                         dev_warn(&client->dev, "power-on detected\n");
 714                 }
 715
 716                 if (ds1307->regs[1] & RX8025_BIT_VDET) {
 717                         ds1307->regs[1] &= ~RX8025_BIT_VDET;
 718                         i2c_smbus_write_byte_data(client,
 719                                                   RX8025_REG_CTRL2 << 4 | 0x08,
 720                                                   ds1307->regs[1]);
 721                         dev_warn(&client->dev, "voltage drop detected\n");
 722                 }
 723
 724                 /* make sure we are running in 24hour mode */
 725                 if (!(ds1307->regs[0] & RX8025_BIT_2412)) {
 726                         u8 hour;
 727
 728                         /* switch to 24 hour mode */
 729                         i2c_smbus_write_byte_data(client,
 730                                                   RX8025_REG_CTRL1 << 4 | 0x08,
 731                                                   ds1307->regs[0] |
 732                                                   RX8025_BIT_2412);
 733
 734                         tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
 735                                         RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
 736                         if (tmp != 2) {
 737                                 pr_debug("read error %d\n", tmp);
 738                                 err = -EIO;
 739                                 goto exit_free;
 740                         }
 741
 742                         /* correct hour */
 743                         hour = bcd2bin(ds1307->regs[DS1307_REG_HOUR]);
 744                         if (hour == 12)
 745                                 hour = 0;
 746                         if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
 747                                 hour += 12;
 748
 749                         i2c_smbus_write_byte_data(client,
 750                                                   DS1307_REG_HOUR << 4 | 0x08,
 751                                                   hour);
 752                 }
 753                 break;
 754         default:
 755                 break;
 756         }
 757
 758 read_rtc:
 759         /* read RTC registers */
 760         tmp = ds1307->read_block_data(ds1307->client, 0, 8, buf);
 761         if (tmp != 8) {
 762                 pr_debug("read error %d\n", tmp);
 763                 err = -EIO;
 764                 goto exit_free;
 765         }
 766
 767         /* minimal sanity checking; some chips (like DS1340) don't
 768          * specify the extra bits as must-be-zero, but there are
 769          * still a few values that are clearly out-of-range.
 770          */
 771         tmp = ds1307->regs[DS1307_REG_SECS];
 772         switch (ds1307->type) {
 773         case ds_1307:
 774         case m41t00:
 775                 /* clock halted?  turn it on, so clock can tick. */
 776                 if (tmp & DS1307_BIT_CH) {
 777                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
 778                         dev_warn(&client->dev, "SET TIME!\n");
 779                         goto read_rtc;
 780                 }
 781                 break;
 782         case ds_1338:
 783                 /* clock halted?  turn it on, so clock can tick. */
 784                 if (tmp & DS1307_BIT_CH)
 785                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
 786
 787                 /* oscillator fault?  clear flag, and warn */
 788                 if (ds1307->regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
 789                         i2c_smbus_write_byte_data(client, DS1307_REG_CONTROL,
 790                                         ds1307->regs[DS1307_REG_CONTROL]
 791                                         & ~DS1338_BIT_OSF);
 792                         dev_warn(&client->dev, "SET TIME!\n");
 793                         goto read_rtc;
 794                 }
 795                 break;
 796         case ds_1340:
 797                 /* clock halted?  turn it on, so clock can tick. */
 798                 if (tmp & DS1340_BIT_nEOSC)
 799                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
 800
 801                 tmp = i2c_smbus_read_byte_data(client, DS1340_REG_FLAG);
 802                 if (tmp < 0) {
 803                         pr_debug("read error %d\n", tmp);
 804                         err = -EIO;
 805                         goto exit_free;
 806                 }
 807
 808                 /* oscillator fault?  clear flag, and warn */
 809                 if (tmp & DS1340_BIT_OSF) {
 810                         i2c_smbus_write_byte_data(client, DS1340_REG_FLAG, 0);
 811                         dev_warn(&client->dev, "SET TIME!\n");
 812                 }
 813                 break;
 814         case rx_8025:
 815         case ds_1337:
 816         case ds_1339:
 817                 break;
 818         }
 819
 820         tmp = ds1307->regs[DS1307_REG_HOUR];
 821         switch (ds1307->type) {
 822         case ds_1340:
 823         case m41t00:
 824                 /* NOTE: ignores century bits; fix before deploying
 825                  * systems that will run through year 2100.
 826                  */
 827                 break;
 828         case rx_8025:
 829                 break;
 830         default:
 831                 if (!(tmp & DS1307_BIT_12HR))
 832                         break;
 833
 834                 /* Be sure we're in 24 hour mode.  Multi-master systems
 835                  * take note...
 836                  */
 837                 tmp = bcd2bin(tmp & 0x1f);
 838                 if (tmp == 12)
 839                         tmp = 0;
 840                 if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
 841                         tmp += 12;
 842                 i2c_smbus_write_byte_data(client,
 843                                 DS1307_REG_HOUR,
 844                                 bin2bcd(tmp));
 845         }
 846
 847         ds1307->rtc = rtc_device_register(client->name, &client->dev,
 848                                 &ds13xx_rtc_ops, THIS_MODULE);
 849         if (IS_ERR(ds1307->rtc)) {
 850                 err = PTR_ERR(ds1307->rtc);
 851                 dev_err(&client->dev,
 852                         "unable to register the class device\n");
 853                 goto exit_free;
 854         }
 855
 856         if (want_irq) {
 857                 err = request_irq(client->irq, ds1307_irq, 0,
 858                           ds1307->rtc->name, client);
 859                 if (err) {
 860                         dev_err(&client->dev,
 861                                 "unable to request IRQ!\n");
 862                         goto exit_irq;
 863                 }
 864                 set_bit(HAS_ALARM, &ds1307->flags);
 865                 dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
 866         }
 867
 868         if (chip->nvram56) {
 869                 err = sysfs_create_bin_file(&client->dev.kobj, &nvram);
 870                 if (err == 0) {
 871                         set_bit(HAS_NVRAM, &ds1307->flags);
 872                         dev_info(&client->dev, "56 bytes nvram\n");
 873                 }
 874         }
 875
 876         return 0;
 877
 878 exit_irq:
 879         if (ds1307->rtc)
 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");