kernel/drivers/rtc/rtc-x1205.c

   1 /*
   2  * An i2c driver for the Xicor/Intersil X1205 RTC
   3  * Copyright 2004 Karen Spearel
   4  * Copyright 2005 Alessandro Zummo
   5  *
   6  * please send all reports to:
   7  *      Karen Spearel <kas111 at gmail dot com>
   8  *      Alessandro Zummo <a.zummo@towertech.it>
   9  *
  10  * based on a lot of other RTC drivers.
  11  *
  12  * Information and datasheet:
  13  * http://www.intersil.com/cda/deviceinfo/0,1477,X1205,00.html
  14  *
  15  * This program is free software; you can redistribute it and/or modify
  16  * it under the terms of the GNU General Public License version 2 as
  17  * published by the Free Software Foundation.
  18  */
  19
  20 #include <linux/i2c.h>
  21 #include <linux/bcd.h>
  22 #include <linux/rtc.h>
  23 #include <linux/delay.h>
  24 #include <linux/module.h>
  25 #include <linux/bitops.h>
  26
  27 #define DRV_VERSION "1.0.8"
  28
  29 /* offsets into CCR area */
  30
  31 #define CCR_SEC                 0
  32 #define CCR_MIN                 1
  33 #define CCR_HOUR                2
  34 #define CCR_MDAY                3
  35 #define CCR_MONTH               4
  36 #define CCR_YEAR                5
  37 #define CCR_WDAY                6
  38 #define CCR_Y2K                 7
  39
  40 #define X1205_REG_SR            0x3F    /* status register */
  41 #define X1205_REG_Y2K           0x37
  42 #define X1205_REG_DW            0x36
  43 #define X1205_REG_YR            0x35
  44 #define X1205_REG_MO            0x34
  45 #define X1205_REG_DT            0x33
  46 #define X1205_REG_HR            0x32
  47 #define X1205_REG_MN            0x31
  48 #define X1205_REG_SC            0x30
  49 #define X1205_REG_DTR           0x13
  50 #define X1205_REG_ATR           0x12
  51 #define X1205_REG_INT           0x11
  52 #define X1205_REG_0             0x10
  53 #define X1205_REG_Y2K1          0x0F
  54 #define X1205_REG_DWA1          0x0E
  55 #define X1205_REG_YRA1          0x0D
  56 #define X1205_REG_MOA1          0x0C
  57 #define X1205_REG_DTA1          0x0B
  58 #define X1205_REG_HRA1          0x0A
  59 #define X1205_REG_MNA1          0x09
  60 #define X1205_REG_SCA1          0x08
  61 #define X1205_REG_Y2K0          0x07
  62 #define X1205_REG_DWA0          0x06
  63 #define X1205_REG_YRA0          0x05
  64 #define X1205_REG_MOA0          0x04
  65 #define X1205_REG_DTA0          0x03
  66 #define X1205_REG_HRA0          0x02
  67 #define X1205_REG_MNA0          0x01
  68 #define X1205_REG_SCA0          0x00
  69
  70 #define X1205_CCR_BASE          0x30    /* Base address of CCR */
  71 #define X1205_ALM0_BASE         0x00    /* Base address of ALARM0 */
  72
  73 #define X1205_SR_RTCF           0x01    /* Clock failure */
  74 #define X1205_SR_WEL            0x02    /* Write Enable Latch */
  75 #define X1205_SR_RWEL           0x04    /* Register Write Enable */
  76 #define X1205_SR_AL0            0x20    /* Alarm 0 match */
  77
  78 #define X1205_DTR_DTR0          0x01
  79 #define X1205_DTR_DTR1          0x02
  80 #define X1205_DTR_DTR2          0x04
  81
  82 #define X1205_HR_MIL            0x80    /* Set in ccr.hour for 24 hr mode */
  83
  84 #define X1205_INT_AL0E          0x20    /* Alarm 0 enable */
  85
  86 static struct i2c_driver x1205_driver;
  87
  88 /*
  89  * In the routines that deal directly with the x1205 hardware, we use
  90  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
  91  * Epoch is initialized as 2000. Time is set to UTC.
  92  */
  93 static int x1205_get_datetime(struct i2c_client *client, struct rtc_time *tm,
  94                                 unsigned char reg_base)
  95 {
  96         unsigned char dt_addr[2] = { 0, reg_base };
  97         unsigned char buf[8];
  98         int i;
  99
 100         struct i2c_msg msgs[] = {
 101                 {/* setup read ptr */
 102                         .addr = client->addr,
 103                         .len = 2,
 104                         .buf = dt_addr
 105                 },
 106                 {/* read date */
 107                         .addr = client->addr,
 108                         .flags = I2C_M_RD,
 109                         .len = 8,
 110                         .buf = buf
 111                 },
 112         };
 113
 114         /* read date registers */
 115         if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
 116                 dev_err(&client->dev, "%s: read error\n", __func__);
 117                 return -EIO;
 118         }
 119
 120         dev_dbg(&client->dev,
 121                 "%s: raw read data - sec=%02x, min=%02x, hr=%02x, "
 122                 "mday=%02x, mon=%02x, year=%02x, wday=%02x, y2k=%02x\n",
 123                 __func__,
 124                 buf[0], buf[1], buf[2], buf[3],
 125                 buf[4], buf[5], buf[6], buf[7]);
 126
 127         /* Mask out the enable bits if these are alarm registers */
 128         if (reg_base < X1205_CCR_BASE)
 129                 for (i = 0; i <= 4; i++)
 130                         buf[i] &= 0x7F;
 131
 132         tm->tm_sec = bcd2bin(buf[CCR_SEC]);
 133         tm->tm_min = bcd2bin(buf[CCR_MIN]);
 134         tm->tm_hour = bcd2bin(buf[CCR_HOUR] & 0x3F); /* hr is 0-23 */
 135         tm->tm_mday = bcd2bin(buf[CCR_MDAY]);
 136         tm->tm_mon = bcd2bin(buf[CCR_MONTH]) - 1; /* mon is 0-11 */
 137         tm->tm_year = bcd2bin(buf[CCR_YEAR])
 138                         + (bcd2bin(buf[CCR_Y2K]) * 100) - 1900;
 139         tm->tm_wday = buf[CCR_WDAY];
 140
 141         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 142                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 143                 __func__,
 144                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 145                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 146
 147         return 0;
 148 }
 149
 150 static int x1205_get_status(struct i2c_client *client, unsigned char *sr)
 151 {
 152         static unsigned char sr_addr[2] = { 0, X1205_REG_SR };
 153
 154         struct i2c_msg msgs[] = {
 155                 {     /* setup read ptr */
 156                         .addr = client->addr,
 157                         .len = 2,
 158                         .buf = sr_addr
 159                 },
 160                 {    /* read status */
 161                         .addr = client->addr,
 162                         .flags = I2C_M_RD,
 163                         .len = 1,
 164                         .buf = sr
 165                 },
 166         };
 167
 168         /* read status register */
 169         if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
 170                 dev_err(&client->dev, "%s: read error\n", __func__);
 171                 return -EIO;
 172         }
 173
 174         return 0;
 175 }
 176
 177 static int x1205_set_datetime(struct i2c_client *client, struct rtc_time *tm,
 178                         u8 reg_base, unsigned char alm_enable)
 179 {
 180         int i, xfer;
 181         unsigned char rdata[10] = { 0, reg_base };
 182         unsigned char *buf = rdata + 2;
 183
 184         static const unsigned char wel[3] = { 0, X1205_REG_SR,
 185                                                 X1205_SR_WEL };
 186
 187         static const unsigned char rwel[3] = { 0, X1205_REG_SR,
 188                                                 X1205_SR_WEL | X1205_SR_RWEL };
 189
 190         static const unsigned char diswe[3] = { 0, X1205_REG_SR, 0 };
 191
 192         dev_dbg(&client->dev,
 193                 "%s: sec=%d min=%d hour=%d mday=%d mon=%d year=%d wday=%d\n",
 194                 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour, tm->tm_mday,
 195                 tm->tm_mon, tm->tm_year, tm->tm_wday);
 196
 197         buf[CCR_SEC] = bin2bcd(tm->tm_sec);
 198         buf[CCR_MIN] = bin2bcd(tm->tm_min);
 199
 200         /* set hour and 24hr bit */
 201         buf[CCR_HOUR] = bin2bcd(tm->tm_hour) | X1205_HR_MIL;
 202
 203         buf[CCR_MDAY] = bin2bcd(tm->tm_mday);
 204
 205         /* month, 1 - 12 */
 206         buf[CCR_MONTH] = bin2bcd(tm->tm_mon + 1);
 207
 208         /* year, since the rtc epoch*/
 209         buf[CCR_YEAR] = bin2bcd(tm->tm_year % 100);
 210         buf[CCR_WDAY] = tm->tm_wday & 0x07;
 211         buf[CCR_Y2K] = bin2bcd((tm->tm_year + 1900) / 100);
 212
 213         /* If writing alarm registers, set compare bits on registers 0-4 */
 214         if (reg_base < X1205_CCR_BASE)
 215                 for (i = 0; i <= 4; i++)
 216                         buf[i] |= 0x80;
 217
 218         /* this sequence is required to unlock the chip */
 219         xfer = i2c_master_send(client, wel, 3);
 220         if (xfer != 3) {
 221                 dev_err(&client->dev, "%s: wel - %d\n", __func__, xfer);
 222                 return -EIO;
 223         }
 224
 225         xfer = i2c_master_send(client, rwel, 3);
 226         if (xfer != 3) {
 227                 dev_err(&client->dev, "%s: rwel - %d\n", __func__, xfer);
 228                 return -EIO;
 229         }
 230
 231         xfer = i2c_master_send(client, rdata, sizeof(rdata));
 232         if (xfer != sizeof(rdata)) {
 233                 dev_err(&client->dev,
 234                         "%s: result=%d addr=%02x, data=%02x\n",
 235                         __func__,
 236                          xfer, rdata[1], rdata[2]);
 237                 return -EIO;
 238         }
 239
 240         /* If we wrote to the nonvolatile region, wait 10msec for write cycle*/
 241         if (reg_base < X1205_CCR_BASE) {
 242                 unsigned char al0e[3] = { 0, X1205_REG_INT, 0 };
 243
 244                 msleep(10);
 245
 246                 /* ...and set or clear the AL0E bit in the INT register */
 247
 248                 /* Need to set RWEL again as the write has cleared it */
 249                 xfer = i2c_master_send(client, rwel, 3);
 250                 if (xfer != 3) {
 251                         dev_err(&client->dev,
 252                                 "%s: aloe rwel - %d\n",
 253                                 __func__,
 254                                 xfer);
 255                         return -EIO;
 256                 }
 257
 258                 if (alm_enable)
 259                         al0e[2] = X1205_INT_AL0E;
 260
 261                 xfer = i2c_master_send(client, al0e, 3);
 262                 if (xfer != 3) {
 263                         dev_err(&client->dev,
 264                                 "%s: al0e - %d\n",
 265                                 __func__,
 266                                 xfer);
 267                         return -EIO;
 268                 }
 269
 270                 /* and wait 10msec again for this write to complete */
 271                 msleep(10);
 272         }
 273
 274         /* disable further writes */
 275         xfer = i2c_master_send(client, diswe, 3);
 276         if (xfer != 3) {
 277                 dev_err(&client->dev, "%s: diswe - %d\n", __func__, xfer);
 278                 return -EIO;
 279         }
 280
 281         return 0;
 282 }
 283
 284 static int x1205_fix_osc(struct i2c_client *client)
 285 {
 286         int err;
 287         struct rtc_time tm;
 288
 289         memset(&tm, 0, sizeof(tm));
 290
 291         err = x1205_set_datetime(client, &tm, X1205_CCR_BASE, 0);
 292         if (err < 0)
 293                 dev_err(&client->dev, "unable to restart the oscillator\n");
 294
 295         return err;
 296 }
 297
 298 static int x1205_get_dtrim(struct i2c_client *client, int *trim)
 299 {
 300         unsigned char dtr;
 301         static unsigned char dtr_addr[2] = { 0, X1205_REG_DTR };
 302
 303         struct i2c_msg msgs[] = {
 304                 {       /* setup read ptr */
 305                         .addr = client->addr,
 306                         .len = 2,
 307                         .buf = dtr_addr
 308                 },
 309                 {      /* read dtr */
 310                         .addr = client->addr,
 311                         .flags = I2C_M_RD,
 312                         .len = 1,
 313                         .buf = &dtr
 314                 },
 315         };
 316
 317         /* read dtr register */
 318         if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
 319                 dev_err(&client->dev, "%s: read error\n", __func__);
 320                 return -EIO;
 321         }
 322
 323         dev_dbg(&client->dev, "%s: raw dtr=%x\n", __func__, dtr);
 324
 325         *trim = 0;
 326
 327         if (dtr & X1205_DTR_DTR0)
 328                 *trim += 20;
 329
 330         if (dtr & X1205_DTR_DTR1)
 331                 *trim += 10;
 332
 333         if (dtr & X1205_DTR_DTR2)
 334                 *trim = -*trim;
 335
 336         return 0;
 337 }
 338
 339 static int x1205_get_atrim(struct i2c_client *client, int *trim)
 340 {
 341         s8 atr;
 342         static unsigned char atr_addr[2] = { 0, X1205_REG_ATR };
 343
 344         struct i2c_msg msgs[] = {
 345                 {/* setup read ptr */
 346                         .addr = client->addr,
 347                         .len = 2,
 348                         .buf = atr_addr
 349                 },
 350                 {/* read atr */
 351                         .addr = client->addr,
 352                         .flags = I2C_M_RD,
 353                         .len = 1,
 354                         .buf = &atr
 355                 },
 356         };
 357
 358         /* read atr register */
 359         if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
 360                 dev_err(&client->dev, "%s: read error\n", __func__);
 361                 return -EIO;
 362         }
 363
 364         dev_dbg(&client->dev, "%s: raw atr=%x\n", __func__, atr);
 365
 366         /* atr is a two's complement value on 6 bits,
 367          * perform sign extension. The formula is
 368          * Catr = (atr * 0.25pF) + 11.00pF.
 369          */
 370         atr = sign_extend32(atr, 5);
 371
 372         dev_dbg(&client->dev, "%s: raw atr=%x (%d)\n", __func__, atr, atr);
 373
 374         *trim = (atr * 250) + 11000;
 375
 376         dev_dbg(&client->dev, "%s: real=%d\n", __func__, *trim);
 377
 378         return 0;
 379 }
 380
 381 struct x1205_limit {
 382         unsigned char reg, mask, min, max;
 383 };
 384
 385 static int x1205_validate_client(struct i2c_client *client)
 386 {
 387         int i, xfer;
 388
 389         /* Probe array. We will read the register at the specified
 390          * address and check if the given bits are zero.
 391          */
 392         static const unsigned char probe_zero_pattern[] = {
 393                 /* register, mask */
 394                 X1205_REG_SR,   0x18,
 395                 X1205_REG_DTR,  0xF8,
 396                 X1205_REG_ATR,  0xC0,
 397                 X1205_REG_INT,  0x18,
 398                 X1205_REG_0,    0xFF,
 399         };
 400
 401         static const struct x1205_limit probe_limits_pattern[] = {
 402                 /* register, mask, min, max */
 403                 { X1205_REG_Y2K,        0xFF,   19,     20      },
 404                 { X1205_REG_DW,         0xFF,   0,      6       },
 405                 { X1205_REG_YR,         0xFF,   0,      99      },
 406                 { X1205_REG_MO,         0xFF,   0,      12      },
 407                 { X1205_REG_DT,         0xFF,   0,      31      },
 408                 { X1205_REG_HR,         0x7F,   0,      23      },
 409                 { X1205_REG_MN,         0xFF,   0,      59      },
 410                 { X1205_REG_SC,         0xFF,   0,      59      },
 411                 { X1205_REG_Y2K1,       0xFF,   19,     20      },
 412                 { X1205_REG_Y2K0,       0xFF,   19,     20      },
 413         };
 414
 415         /* check that registers have bits a 0 where expected */
 416         for (i = 0; i < ARRAY_SIZE(probe_zero_pattern); i += 2) {
 417                 unsigned char buf;
 418
 419                 unsigned char addr[2] = { 0, probe_zero_pattern[i] };
 420
 421                 struct i2c_msg msgs[2] = {
 422                         {
 423                                 .addr = client->addr,
 424                                 .len = 2,
 425                                 .buf = addr
 426                         },
 427                         {
 428                                 .addr = client->addr,
 429                                 .flags = I2C_M_RD,
 430                                 .len = 1,
 431                                 .buf = &buf
 432                         },
 433                 };
 434
 435                 xfer = i2c_transfer(client->adapter, msgs, 2);
 436                 if (xfer != 2) {
 437                         dev_err(&client->dev,
 438                                 "%s: could not read register %x\n",
 439                                 __func__, probe_zero_pattern[i]);
 440
 441                         return -EIO;
 442                 }
 443
 444                 if ((buf & probe_zero_pattern[i+1]) != 0) {
 445                         dev_err(&client->dev,
 446                                 "%s: register=%02x, zero pattern=%d, value=%x\n",
 447                                 __func__, probe_zero_pattern[i], i, buf);
 448
 449                         return -ENODEV;
 450                 }
 451         }
 452
 453         /* check limits (only registers with bcd values) */
 454         for (i = 0; i < ARRAY_SIZE(probe_limits_pattern); i++) {
 455                 unsigned char reg, value;
 456
 457                 unsigned char addr[2] = { 0, probe_limits_pattern[i].reg };
 458
 459                 struct i2c_msg msgs[2] = {
 460                         {
 461                                 .addr = client->addr,
 462                                 .len = 2,
 463                                 .buf = addr
 464                         },
 465                         {
 466                                 .addr = client->addr,
 467                                 .flags = I2C_M_RD,
 468                                 .len = 1,
 469                                 .buf = &reg
 470                         },
 471                 };
 472
 473                 xfer = i2c_transfer(client->adapter, msgs, 2);
 474                 if (xfer != 2) {
 475                         dev_err(&client->dev,
 476                                 "%s: could not read register %x\n",
 477                                 __func__, probe_limits_pattern[i].reg);
 478
 479                         return -EIO;
 480                 }
 481
 482                 value = bcd2bin(reg & probe_limits_pattern[i].mask);
 483
 484                 if (value > probe_limits_pattern[i].max ||
 485                         value < probe_limits_pattern[i].min) {
 486                         dev_dbg(&client->dev,
 487                                 "%s: register=%x, lim pattern=%d, value=%d\n",
 488                                 __func__, probe_limits_pattern[i].reg,
 489                                 i, value);
 490
 491                         return -ENODEV;
 492                 }
 493         }
 494
 495         return 0;
 496 }
 497
 498 static int x1205_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 499 {
 500         int err;
 501         unsigned char intreg, status;
 502         static unsigned char int_addr[2] = { 0, X1205_REG_INT };
 503         struct i2c_client *client = to_i2c_client(dev);
 504         struct i2c_msg msgs[] = {
 505                 { /* setup read ptr */
 506                         .addr = client->addr,
 507                         .len = 2,
 508                         .buf = int_addr
 509                 },
 510                 {/* read INT register */
 511
 512                         .addr = client->addr,
 513                         .flags = I2C_M_RD,
 514                         .len = 1,
 515                         .buf = &intreg
 516                 },
 517         };
 518
 519         /* read interrupt register and status register */
 520         if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
 521                 dev_err(&client->dev, "%s: read error\n", __func__);
 522                 return -EIO;
 523         }
 524         err = x1205_get_status(client, &status);
 525         if (err == 0) {
 526                 alrm->pending = (status & X1205_SR_AL0) ? 1 : 0;
 527                 alrm->enabled = (intreg & X1205_INT_AL0E) ? 1 : 0;
 528                 err = x1205_get_datetime(client, &alrm->time, X1205_ALM0_BASE);
 529         }
 530         return err;
 531 }
 532
 533 static int x1205_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 534 {
 535         return x1205_set_datetime(to_i2c_client(dev),
 536                 &alrm->time, X1205_ALM0_BASE, alrm->enabled);
 537 }
 538
 539 static int x1205_rtc_read_time(struct device *dev, struct rtc_time *tm)
 540 {
 541         return x1205_get_datetime(to_i2c_client(dev),
 542                 tm, X1205_CCR_BASE);
 543 }
 544
 545 static int x1205_rtc_set_time(struct device *dev, struct rtc_time *tm)
 546 {
 547         return x1205_set_datetime(to_i2c_client(dev),
 548                 tm, X1205_CCR_BASE, 0);
 549 }
 550
 551 static int x1205_rtc_proc(struct device *dev, struct seq_file *seq)
 552 {
 553         int err, dtrim, atrim;
 554
 555         err = x1205_get_dtrim(to_i2c_client(dev), &dtrim);
 556         if (!err)
 557                 seq_printf(seq, "digital_trim\t: %d ppm\n", dtrim);
 558
 559         err = x1205_get_atrim(to_i2c_client(dev), &atrim);
 560         if (!err)
 561                 seq_printf(seq, "analog_trim\t: %d.%02d pF\n",
 562                         atrim / 1000, atrim % 1000);
 563         return 0;
 564 }
 565
 566 static const struct rtc_class_ops x1205_rtc_ops = {
 567         .proc           = x1205_rtc_proc,
 568         .read_time      = x1205_rtc_read_time,
 569         .set_time       = x1205_rtc_set_time,
 570         .read_alarm     = x1205_rtc_read_alarm,
 571         .set_alarm      = x1205_rtc_set_alarm,
 572 };
 573
 574 static ssize_t x1205_sysfs_show_atrim(struct device *dev,
 575                                 struct device_attribute *attr, char *buf)
 576 {
 577         int err, atrim;
 578
 579         err = x1205_get_atrim(to_i2c_client(dev), &atrim);
 580         if (err)
 581                 return err;
 582
 583         return sprintf(buf, "%d.%02d pF\n", atrim / 1000, atrim % 1000);
 584 }
 585 static DEVICE_ATTR(atrim, S_IRUGO, x1205_sysfs_show_atrim, NULL);
 586
 587 static ssize_t x1205_sysfs_show_dtrim(struct device *dev,
 588                                 struct device_attribute *attr, char *buf)
 589 {
 590         int err, dtrim;
 591
 592         err = x1205_get_dtrim(to_i2c_client(dev), &dtrim);
 593         if (err)
 594                 return err;
 595
 596         return sprintf(buf, "%d ppm\n", dtrim);
 597 }
 598 static DEVICE_ATTR(dtrim, S_IRUGO, x1205_sysfs_show_dtrim, NULL);
 599
 600 static int x1205_sysfs_register(struct device *dev)
 601 {
 602         int err;
 603
 604         err = device_create_file(dev, &dev_attr_atrim);
 605         if (err)
 606                 return err;
 607
 608         err = device_create_file(dev, &dev_attr_dtrim);
 609         if (err)
 610                 device_remove_file(dev, &dev_attr_atrim);
 611
 612         return err;
 613 }
 614
 615 static void x1205_sysfs_unregister(struct device *dev)
 616 {
 617         device_remove_file(dev, &dev_attr_atrim);
 618         device_remove_file(dev, &dev_attr_dtrim);
 619 }
 620
 621
 622 static int x1205_probe(struct i2c_client *client,
 623                         const struct i2c_device_id *id)
 624 {
 625         int err = 0;
 626         unsigned char sr;
 627         struct rtc_device *rtc;
 628
 629         dev_dbg(&client->dev, "%s\n", __func__);
 630
 631         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 632                 return -ENODEV;
 633
 634         if (x1205_validate_client(client) < 0)
 635                 return -ENODEV;
 636
 637         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 638
 639         rtc = devm_rtc_device_register(&client->dev, x1205_driver.driver.name,
 640                                         &x1205_rtc_ops, THIS_MODULE);
 641
 642         if (IS_ERR(rtc))
 643                 return PTR_ERR(rtc);
 644
 645         i2c_set_clientdata(client, rtc);
 646
 647         /* Check for power failures and eventually enable the osc */
 648         err = x1205_get_status(client, &sr);
 649         if (!err) {
 650                 if (sr & X1205_SR_RTCF) {
 651                         dev_err(&client->dev,
 652                                 "power failure detected, "
 653                                 "please set the clock\n");
 654                         udelay(50);
 655                         x1205_fix_osc(client);
 656                 }
 657         } else {
 658                 dev_err(&client->dev, "couldn't read status\n");
 659         }
 660
 661         err = x1205_sysfs_register(&client->dev);
 662         if (err)
 663                 dev_err(&client->dev, "Unable to create sysfs entries\n");
 664
 665         return 0;
 666 }
 667
 668 static int x1205_remove(struct i2c_client *client)
 669 {
 670         x1205_sysfs_unregister(&client->dev);
 671         return 0;
 672 }
 673
 674 static const struct i2c_device_id x1205_id[] = {
 675         { "x1205", 0 },
 676         { }
 677 };
 678 MODULE_DEVICE_TABLE(i2c, x1205_id);
 679
 680 static struct i2c_driver x1205_driver = {
 681         .driver         = {
 682                 .name   = "rtc-x1205",
 683         },
 684         .probe          = x1205_probe,
 685         .remove         = x1205_remove,
 686         .id_table       = x1205_id,
 687 };
 688
 689 module_i2c_driver(x1205_driver);
 690
 691 MODULE_AUTHOR(
 692         "Karen Spearel <kas111 at gmail dot com>, "
 693         "Alessandro Zummo <a.zummo@towertech.it>");
 694 MODULE_DESCRIPTION("Xicor/Intersil X1205 RTC driver");
 695 MODULE_LICENSE("GPL");
 696 MODULE_VERSION(DRV_VERSION);