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