drivers/rtc/rtc-isl1208.c

   1 /*
   2  * Intersil ISL1208 rtc class driver
   3  *
   4  * Copyright 2005,2006 Hebert Valerio Riedel <hvr@gnu.org>
   5  *
   6  *  This program is free software; you can redistribute  it and/or modify it
   7  *  under  the terms of  the GNU General  Public License as published by the
   8  *  Free Software Foundation;  either version 2 of the  License, or (at your
   9  *  option) any later version.
  10  *
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/i2c.h>
  15 #include <linux/bcd.h>
  16 #include <linux/rtc.h>
  17
  18 #define DRV_VERSION "0.3"
  19
  20 /* Register map */
  21 /* rtc section */
  22 #define ISL1208_REG_SC  0x00
  23 #define ISL1208_REG_MN  0x01
  24 #define ISL1208_REG_HR  0x02
  25 #define ISL1208_REG_HR_MIL     (1<<7)   /* 24h/12h mode */
  26 #define ISL1208_REG_HR_PM      (1<<5)   /* PM/AM bit in 12h mode */
  27 #define ISL1208_REG_DT  0x03
  28 #define ISL1208_REG_MO  0x04
  29 #define ISL1208_REG_YR  0x05
  30 #define ISL1208_REG_DW  0x06
  31 #define ISL1208_RTC_SECTION_LEN 7
  32
  33 /* control/status section */
  34 #define ISL1208_REG_SR  0x07
  35 #define ISL1208_REG_SR_ARST    (1<<7)   /* auto reset */
  36 #define ISL1208_REG_SR_XTOSCB  (1<<6)   /* crystal oscillator */
  37 #define ISL1208_REG_SR_WRTC    (1<<4)   /* write rtc */
  38 #define ISL1208_REG_SR_ALM     (1<<2)   /* alarm */
  39 #define ISL1208_REG_SR_BAT     (1<<1)   /* battery */
  40 #define ISL1208_REG_SR_RTCF    (1<<0)   /* rtc fail */
  41 #define ISL1208_REG_INT 0x08
  42 #define ISL1208_REG_INT_ALME   (1<<6)   /* alarm enable */
  43 #define ISL1208_REG_INT_IM     (1<<7)   /* interrupt/alarm mode */
  44 #define ISL1208_REG_09  0x09    /* reserved */
  45 #define ISL1208_REG_ATR 0x0a
  46 #define ISL1208_REG_DTR 0x0b
  47
  48 /* alarm section */
  49 #define ISL1208_REG_SCA 0x0c
  50 #define ISL1208_REG_MNA 0x0d
  51 #define ISL1208_REG_HRA 0x0e
  52 #define ISL1208_REG_DTA 0x0f
  53 #define ISL1208_REG_MOA 0x10
  54 #define ISL1208_REG_DWA 0x11
  55 #define ISL1208_ALARM_SECTION_LEN 6
  56
  57 /* user section */
  58 #define ISL1208_REG_USR1 0x12
  59 #define ISL1208_REG_USR2 0x13
  60 #define ISL1208_USR_SECTION_LEN 2
  61
  62 static struct i2c_driver isl1208_driver;
  63
  64 /* block read */
  65 static int
  66 isl1208_i2c_read_regs(struct i2c_client *client, u8 reg, u8 buf[],
  67                       unsigned len)
  68 {
  69         u8 reg_addr[1] = { reg };
  70         struct i2c_msg msgs[2] = {
  71                 {client->addr, 0, sizeof(reg_addr), reg_addr}
  72                 ,
  73                 {client->addr, I2C_M_RD, len, buf}
  74         };
  75         int ret;
  76
  77         BUG_ON(reg > ISL1208_REG_USR2);
  78         BUG_ON(reg + len > ISL1208_REG_USR2 + 1);
  79
  80         ret = i2c_transfer(client->adapter, msgs, 2);
  81         if (ret > 0)
  82                 ret = 0;
  83         return ret;
  84 }
  85
  86 /* block write */
  87 static int
  88 isl1208_i2c_set_regs(struct i2c_client *client, u8 reg, u8 const buf[],
  89                      unsigned len)
  90 {
  91         u8 i2c_buf[ISL1208_REG_USR2 + 2];
  92         struct i2c_msg msgs[1] = {
  93                 {client->addr, 0, len + 1, i2c_buf}
  94         };
  95         int ret;
  96
  97         BUG_ON(reg > ISL1208_REG_USR2);
  98         BUG_ON(reg + len > ISL1208_REG_USR2 + 1);
  99
 100         i2c_buf[0] = reg;
 101         memcpy(&i2c_buf[1], &buf[0], len);
 102
 103         ret = i2c_transfer(client->adapter, msgs, 1);
 104         if (ret > 0)
 105                 ret = 0;
 106         return ret;
 107 }
 108
 109 /* simple check to see wether we have a isl1208 */
 110 static int
 111 isl1208_i2c_validate_client(struct i2c_client *client)
 112 {
 113         u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
 114         u8 zero_mask[ISL1208_RTC_SECTION_LEN] = {
 115                 0x80, 0x80, 0x40, 0xc0, 0xe0, 0x00, 0xf8
 116         };
 117         int i;
 118         int ret;
 119
 120         ret = isl1208_i2c_read_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
 121         if (ret < 0)
 122                 return ret;
 123
 124         for (i = 0; i < ISL1208_RTC_SECTION_LEN; ++i) {
 125                 if (regs[i] & zero_mask[i])     /* check if bits are cleared */
 126                         return -ENODEV;
 127         }
 128
 129         return 0;
 130 }
 131
 132 static int
 133 isl1208_i2c_get_sr(struct i2c_client *client)
 134 {
 135         int sr = i2c_smbus_read_byte_data(client, ISL1208_REG_SR);
 136         if (sr < 0)
 137                 return -EIO;
 138
 139         return sr;
 140 }
 141
 142 static int
 143 isl1208_i2c_get_atr(struct i2c_client *client)
 144 {
 145         int atr = i2c_smbus_read_byte_data(client, ISL1208_REG_ATR);
 146         if (atr < 0)
 147                 return atr;
 148
 149         /* The 6bit value in the ATR register controls the load
 150          * capacitance C_load * in steps of 0.25pF
 151          *
 152          * bit (1<<5) of the ATR register is inverted
 153          *
 154          * C_load(ATR=0x20) =  4.50pF
 155          * C_load(ATR=0x00) = 12.50pF
 156          * C_load(ATR=0x1f) = 20.25pF
 157          *
 158          */
 159
 160         atr &= 0x3f;            /* mask out lsb */
 161         atr ^= 1 << 5;          /* invert 6th bit */
 162         atr += 2 * 9;           /* add offset of 4.5pF; unit[atr] = 0.25pF */
 163
 164         return atr;
 165 }
 166
 167 static int
 168 isl1208_i2c_get_dtr(struct i2c_client *client)
 169 {
 170         int dtr = i2c_smbus_read_byte_data(client, ISL1208_REG_DTR);
 171         if (dtr < 0)
 172                 return -EIO;
 173
 174         /* dtr encodes adjustments of {-60,-40,-20,0,20,40,60} ppm */
 175         dtr = ((dtr & 0x3) * 20) * (dtr & (1 << 2) ? -1 : 1);
 176
 177         return dtr;
 178 }
 179
 180 static int
 181 isl1208_i2c_get_usr(struct i2c_client *client)
 182 {
 183         u8 buf[ISL1208_USR_SECTION_LEN] = { 0, };
 184         int ret;
 185
 186         ret = isl1208_i2c_read_regs(client, ISL1208_REG_USR1, buf,
 187                                     ISL1208_USR_SECTION_LEN);
 188         if (ret < 0)
 189                 return ret;
 190
 191         return (buf[1] << 8) | buf[0];
 192 }
 193
 194 static int
 195 isl1208_i2c_set_usr(struct i2c_client *client, u16 usr)
 196 {
 197         u8 buf[ISL1208_USR_SECTION_LEN];
 198
 199         buf[0] = usr & 0xff;
 200         buf[1] = (usr >> 8) & 0xff;
 201
 202         return isl1208_i2c_set_regs(client, ISL1208_REG_USR1, buf,
 203                                     ISL1208_USR_SECTION_LEN);
 204 }
 205
 206 static int
 207 isl1208_rtc_toggle_alarm(struct i2c_client *client, int enable)
 208 {
 209         int icr = i2c_smbus_read_byte_data(client, ISL1208_REG_INT);
 210
 211         if (icr < 0) {
 212                 dev_err(&client->dev, "%s: reading INT failed\n", __func__);
 213                 return icr;
 214         }
 215
 216         if (enable)
 217                 icr |= ISL1208_REG_INT_ALME | ISL1208_REG_INT_IM;
 218         else
 219                 icr &= ~(ISL1208_REG_INT_ALME | ISL1208_REG_INT_IM);
 220
 221         icr = i2c_smbus_write_byte_data(client, ISL1208_REG_INT, icr);
 222         if (icr < 0) {
 223                 dev_err(&client->dev, "%s: writing INT failed\n", __func__);
 224                 return icr;
 225         }
 226
 227         return 0;
 228 }
 229
 230 static int
 231 isl1208_rtc_proc(struct device *dev, struct seq_file *seq)
 232 {
 233         struct i2c_client *const client = to_i2c_client(dev);
 234         int sr, dtr, atr, usr;
 235
 236         sr = isl1208_i2c_get_sr(client);
 237         if (sr < 0) {
 238                 dev_err(&client->dev, "%s: reading SR failed\n", __func__);
 239                 return sr;
 240         }
 241
 242         seq_printf(seq, "status_reg\t:%s%s%s%s%s%s (0x%.2x)\n",
 243                    (sr & ISL1208_REG_SR_RTCF) ? " RTCF" : "",
 244                    (sr & ISL1208_REG_SR_BAT) ? " BAT" : "",
 245                    (sr & ISL1208_REG_SR_ALM) ? " ALM" : "",
 246                    (sr & ISL1208_REG_SR_WRTC) ? " WRTC" : "",
 247                    (sr & ISL1208_REG_SR_XTOSCB) ? " XTOSCB" : "",
 248                    (sr & ISL1208_REG_SR_ARST) ? " ARST" : "", sr);
 249
 250         seq_printf(seq, "batt_status\t: %s\n",
 251                    (sr & ISL1208_REG_SR_RTCF) ? "bad" : "okay");
 252
 253         dtr = isl1208_i2c_get_dtr(client);
 254         if (dtr >= 0 - 1)
 255                 seq_printf(seq, "digital_trim\t: %d ppm\n", dtr);
 256
 257         atr = isl1208_i2c_get_atr(client);
 258         if (atr >= 0)
 259                 seq_printf(seq, "analog_trim\t: %d.%.2d pF\n",
 260                            atr >> 2, (atr & 0x3) * 25);
 261
 262         usr = isl1208_i2c_get_usr(client);
 263         if (usr >= 0)
 264                 seq_printf(seq, "user_data\t: 0x%.4x\n", usr);
 265
 266         return 0;
 267 }
 268
 269 static int
 270 isl1208_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)
 271 {
 272         int sr;
 273         u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
 274
 275         sr = isl1208_i2c_get_sr(client);
 276         if (sr < 0) {
 277                 dev_err(&client->dev, "%s: reading SR failed\n", __func__);
 278                 return -EIO;
 279         }
 280
 281         sr = isl1208_i2c_read_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
 282         if (sr < 0) {
 283                 dev_err(&client->dev, "%s: reading RTC section failed\n",
 284                         __func__);
 285                 return sr;
 286         }
 287
 288         tm->tm_sec = bcd2bin(regs[ISL1208_REG_SC]);
 289         tm->tm_min = bcd2bin(regs[ISL1208_REG_MN]);
 290
 291         /* HR field has a more complex interpretation */
 292         {
 293                 const u8 _hr = regs[ISL1208_REG_HR];
 294                 if (_hr & ISL1208_REG_HR_MIL)   /* 24h format */
 295                         tm->tm_hour = bcd2bin(_hr & 0x3f);
 296                 else {
 297                         /* 12h format */
 298                         tm->tm_hour = bcd2bin(_hr & 0x1f);
 299                         if (_hr & ISL1208_REG_HR_PM)    /* PM flag set */
 300                                 tm->tm_hour += 12;
 301                 }
 302         }
 303
 304         tm->tm_mday = bcd2bin(regs[ISL1208_REG_DT]);
 305         tm->tm_mon = bcd2bin(regs[ISL1208_REG_MO]) - 1; /* rtc starts at 1 */
 306         tm->tm_year = bcd2bin(regs[ISL1208_REG_YR]) + 100;
 307         tm->tm_wday = bcd2bin(regs[ISL1208_REG_DW]);
 308
 309         return 0;
 310 }
 311
 312 static int
 313 isl1208_i2c_read_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
 314 {
 315         struct rtc_time *const tm = &alarm->time;
 316         u8 regs[ISL1208_ALARM_SECTION_LEN] = { 0, };
 317         int icr, yr, sr = isl1208_i2c_get_sr(client);
 318
 319         if (sr < 0) {
 320                 dev_err(&client->dev, "%s: reading SR failed\n", __func__);
 321                 return sr;
 322         }
 323
 324         sr = isl1208_i2c_read_regs(client, ISL1208_REG_SCA, regs,
 325                                    ISL1208_ALARM_SECTION_LEN);
 326         if (sr < 0) {
 327                 dev_err(&client->dev, "%s: reading alarm section failed\n",
 328                         __func__);
 329                 return sr;
 330         }
 331
 332         /* MSB of each alarm register is an enable bit */
 333         tm->tm_sec = bcd2bin(regs[ISL1208_REG_SCA - ISL1208_REG_SCA] & 0x7f);
 334         tm->tm_min = bcd2bin(regs[ISL1208_REG_MNA - ISL1208_REG_SCA] & 0x7f);
 335         tm->tm_hour = bcd2bin(regs[ISL1208_REG_HRA - ISL1208_REG_SCA] & 0x3f);
 336         tm->tm_mday = bcd2bin(regs[ISL1208_REG_DTA - ISL1208_REG_SCA] & 0x3f);
 337         tm->tm_mon =
 338                 bcd2bin(regs[ISL1208_REG_MOA - ISL1208_REG_SCA] & 0x1f) - 1;
 339         tm->tm_wday = bcd2bin(regs[ISL1208_REG_DWA - ISL1208_REG_SCA] & 0x03);
 340
 341         /* The alarm doesn't store the year so get it from the rtc section */
 342         yr = i2c_smbus_read_byte_data(client, ISL1208_REG_YR);
 343         if (yr < 0) {
 344                 dev_err(&client->dev, "%s: reading RTC YR failed\n", __func__);
 345                 return yr;
 346         }
 347         tm->tm_year = bcd2bin(yr) + 100;
 348
 349         icr = i2c_smbus_read_byte_data(client, ISL1208_REG_INT);
 350         if (icr < 0) {
 351                 dev_err(&client->dev, "%s: reading INT failed\n", __func__);
 352                 return icr;
 353         }
 354         alarm->enabled = !!(icr & ISL1208_REG_INT_ALME);
 355
 356         return 0;
 357 }
 358
 359 static int
 360 isl1208_i2c_set_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
 361 {
 362         struct rtc_time *alarm_tm = &alarm->time;
 363         u8 regs[ISL1208_ALARM_SECTION_LEN] = { 0, };
 364         const int offs = ISL1208_REG_SCA;
 365         unsigned long rtc_secs, alarm_secs;
 366         struct rtc_time rtc_tm;
 367         int err, enable;
 368
 369         err = isl1208_i2c_read_time(client, &rtc_tm);
 370         if (err)
 371                 return err;
 372         err = rtc_tm_to_time(&rtc_tm, &rtc_secs);
 373         if (err)
 374                 return err;
 375         err = rtc_tm_to_time(alarm_tm, &alarm_secs);
 376         if (err)
 377                 return err;
 378
 379         /* If the alarm time is before the current time disable the alarm */
 380         if (!alarm->enabled || alarm_secs <= rtc_secs)
 381                 enable = 0x00;
 382         else
 383                 enable = 0x80;
 384
 385         /* Program the alarm and enable it for each setting */
 386         regs[ISL1208_REG_SCA - offs] = bin2bcd(alarm_tm->tm_sec) | enable;
 387         regs[ISL1208_REG_MNA - offs] = bin2bcd(alarm_tm->tm_min) | enable;
 388         regs[ISL1208_REG_HRA - offs] = bin2bcd(alarm_tm->tm_hour) |
 389                 ISL1208_REG_HR_MIL | enable;
 390
 391         regs[ISL1208_REG_DTA - offs] = bin2bcd(alarm_tm->tm_mday) | enable;
 392         regs[ISL1208_REG_MOA - offs] = bin2bcd(alarm_tm->tm_mon + 1) | enable;
 393         regs[ISL1208_REG_DWA - offs] = bin2bcd(alarm_tm->tm_wday & 7) | enable;
 394
 395         /* write ALARM registers */
 396         err = isl1208_i2c_set_regs(client, offs, regs,
 397                                   ISL1208_ALARM_SECTION_LEN);
 398         if (err < 0) {
 399                 dev_err(&client->dev, "%s: writing ALARM section failed\n",
 400                         __func__);
 401                 return err;
 402         }
 403
 404         err = isl1208_rtc_toggle_alarm(client, enable);
 405         if (err)
 406                 return err;
 407
 408         return 0;
 409 }
 410
 411 static int
 412 isl1208_rtc_read_time(struct device *dev, struct rtc_time *tm)
 413 {
 414         return isl1208_i2c_read_time(to_i2c_client(dev), tm);
 415 }
 416
 417 static int
 418 isl1208_i2c_set_time(struct i2c_client *client, struct rtc_time const *tm)
 419 {
 420         int sr;
 421         u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
 422
 423         /* The clock has an 8 bit wide bcd-coded register (they never learn)
 424          * for the year. tm_year is an offset from 1900 and we are interested
 425          * in the 2000-2099 range, so any value less than 100 is invalid.
 426          */
 427         if (tm->tm_year < 100)
 428                 return -EINVAL;
 429
 430         regs[ISL1208_REG_SC] = bin2bcd(tm->tm_sec);
 431         regs[ISL1208_REG_MN] = bin2bcd(tm->tm_min);
 432         regs[ISL1208_REG_HR] = bin2bcd(tm->tm_hour) | ISL1208_REG_HR_MIL;
 433
 434         regs[ISL1208_REG_DT] = bin2bcd(tm->tm_mday);
 435         regs[ISL1208_REG_MO] = bin2bcd(tm->tm_mon + 1);
 436         regs[ISL1208_REG_YR] = bin2bcd(tm->tm_year - 100);
 437
 438         regs[ISL1208_REG_DW] = bin2bcd(tm->tm_wday & 7);
 439
 440         sr = isl1208_i2c_get_sr(client);
 441         if (sr < 0) {
 442                 dev_err(&client->dev, "%s: reading SR failed\n", __func__);
 443                 return sr;
 444         }
 445
 446         /* set WRTC */
 447         sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR,
 448                                        sr | ISL1208_REG_SR_WRTC);
 449         if (sr < 0) {
 450                 dev_err(&client->dev, "%s: writing SR failed\n", __func__);
 451                 return sr;
 452         }
 453
 454         /* write RTC registers */
 455         sr = isl1208_i2c_set_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
 456         if (sr < 0) {
 457                 dev_err(&client->dev, "%s: writing RTC section failed\n",
 458                         __func__);
 459                 return sr;
 460         }
 461
 462         /* clear WRTC again */
 463         sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR,
 464                                        sr & ~ISL1208_REG_SR_WRTC);
 465         if (sr < 0) {
 466                 dev_err(&client->dev, "%s: writing SR failed\n", __func__);
 467                 return sr;
 468         }
 469
 470         return 0;
 471 }
 472
 473
 474 static int
 475 isl1208_rtc_set_time(struct device *dev, struct rtc_time *tm)
 476 {
 477         return isl1208_i2c_set_time(to_i2c_client(dev), tm);
 478 }
 479
 480 static int
 481 isl1208_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 482 {
 483         return isl1208_i2c_read_alarm(to_i2c_client(dev), alarm);
 484 }
 485
 486 static int
 487 isl1208_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 488 {
 489         return isl1208_i2c_set_alarm(to_i2c_client(dev), alarm);
 490 }
 491
 492 static irqreturn_t
 493 isl1208_rtc_interrupt(int irq, void *data)
 494 {
 495         unsigned long timeout = jiffies + msecs_to_jiffies(1000);
 496         struct i2c_client *client = data;
 497         int handled = 0, sr, err;
 498
 499         /*
 500          * I2C reads get NAK'ed if we read straight away after an interrupt?
 501          * Using a mdelay/msleep didn't seem to help either, so we work around
 502          * this by continually trying to read the register for a short time.
 503          */
 504         while (1) {
 505                 sr = isl1208_i2c_get_sr(client);
 506                 if (sr >= 0)
 507                         break;
 508
 509                 if (time_after(jiffies, timeout)) {
 510                         dev_err(&client->dev, "%s: reading SR failed\n",
 511                                 __func__);
 512                         return sr;
 513                 }
 514         }
 515
 516         if (sr & ISL1208_REG_SR_ALM) {
 517                 dev_dbg(&client->dev, "alarm!\n");
 518
 519                 /* Clear the alarm */
 520                 sr &= ~ISL1208_REG_SR_ALM;
 521                 sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR, sr);
 522                 if (sr < 0)
 523                         dev_err(&client->dev, "%s: writing SR failed\n",
 524                                 __func__);
 525                 else
 526                         handled = 1;
 527
 528                 /* Disable the alarm */
 529                 err = isl1208_rtc_toggle_alarm(client, 0);
 530                 if (err)
 531                         return err;
 532         }
 533
 534         return handled ? IRQ_HANDLED : IRQ_NONE;
 535 }
 536
 537 static const struct rtc_class_ops isl1208_rtc_ops = {
 538         .proc = isl1208_rtc_proc,
 539         .read_time = isl1208_rtc_read_time,
 540         .set_time = isl1208_rtc_set_time,
 541         .read_alarm = isl1208_rtc_read_alarm,
 542         .set_alarm = isl1208_rtc_set_alarm,
 543 };
 544
 545 /* sysfs interface */
 546
 547 static ssize_t
 548 isl1208_sysfs_show_atrim(struct device *dev,
 549                          struct device_attribute *attr, char *buf)
 550 {
 551         int atr = isl1208_i2c_get_atr(to_i2c_client(dev));
 552         if (atr < 0)
 553                 return atr;
 554
 555         return sprintf(buf, "%d.%.2d pF\n", atr >> 2, (atr & 0x3) * 25);
 556 }
 557
 558 static DEVICE_ATTR(atrim, S_IRUGO, isl1208_sysfs_show_atrim, NULL);
 559
 560 static ssize_t
 561 isl1208_sysfs_show_dtrim(struct device *dev,
 562                          struct device_attribute *attr, char *buf)
 563 {
 564         int dtr = isl1208_i2c_get_dtr(to_i2c_client(dev));
 565         if (dtr < 0)
 566                 return dtr;
 567
 568         return sprintf(buf, "%d ppm\n", dtr);
 569 }
 570
 571 static DEVICE_ATTR(dtrim, S_IRUGO, isl1208_sysfs_show_dtrim, NULL);
 572
 573 static ssize_t
 574 isl1208_sysfs_show_usr(struct device *dev,
 575                        struct device_attribute *attr, char *buf)
 576 {
 577         int usr = isl1208_i2c_get_usr(to_i2c_client(dev));
 578         if (usr < 0)
 579                 return usr;
 580
 581         return sprintf(buf, "0x%.4x\n", usr);
 582 }
 583
 584 static ssize_t
 585 isl1208_sysfs_store_usr(struct device *dev,
 586                         struct device_attribute *attr,
 587                         const char *buf, size_t count)
 588 {
 589         int usr = -1;
 590
 591         if (buf[0] == '0' && (buf[1] == 'x' || buf[1] == 'X')) {
 592                 if (sscanf(buf, "%x", &usr) != 1)
 593                         return -EINVAL;
 594         } else {
 595                 if (sscanf(buf, "%d", &usr) != 1)
 596                         return -EINVAL;
 597         }
 598
 599         if (usr < 0 || usr > 0xffff)
 600                 return -EINVAL;
 601
 602         return isl1208_i2c_set_usr(to_i2c_client(dev), usr) ? -EIO : count;
 603 }
 604
 605 static DEVICE_ATTR(usr, S_IRUGO | S_IWUSR, isl1208_sysfs_show_usr,
 606                    isl1208_sysfs_store_usr);
 607
 608 static struct attribute *isl1208_rtc_attrs[] = {
 609         &dev_attr_atrim.attr,
 610         &dev_attr_dtrim.attr,
 611         &dev_attr_usr.attr,
 612         NULL
 613 };
 614
 615 static const struct attribute_group isl1208_rtc_sysfs_files = {
 616         .attrs  = isl1208_rtc_attrs,
 617 };
 618
 619 static int
 620 isl1208_probe(struct i2c_client *client, const struct i2c_device_id *id)
 621 {
 622         int rc = 0;
 623         struct rtc_device *rtc;
 624
 625         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 626                 return -ENODEV;
 627
 628         if (isl1208_i2c_validate_client(client) < 0)
 629                 return -ENODEV;
 630
 631         dev_info(&client->dev,
 632                  "chip found, driver version " DRV_VERSION "\n");
 633
 634         if (client->irq > 0) {
 635                 rc = request_threaded_irq(client->irq, NULL,
 636                                           isl1208_rtc_interrupt,
 637                                           IRQF_SHARED,
 638                                           isl1208_driver.driver.name, client);
 639                 if (!rc) {
 640                         device_init_wakeup(&client->dev, 1);
 641                         enable_irq_wake(client->irq);
 642                 } else {
 643                         dev_err(&client->dev,
 644                                 "Unable to request irq %d, no alarm support\n",
 645                                 client->irq);
 646                         client->irq = 0;
 647                 }
 648         }
 649
 650         rtc = rtc_device_register(isl1208_driver.driver.name,
 651                                   &client->dev, &isl1208_rtc_ops,
 652                                   THIS_MODULE);
 653         if (IS_ERR(rtc)) {
 654                 rc = PTR_ERR(rtc);
 655                 goto exit_free_irq;
 656         }
 657
 658         i2c_set_clientdata(client, rtc);
 659
 660         rc = isl1208_i2c_get_sr(client);
 661         if (rc < 0) {
 662                 dev_err(&client->dev, "reading status failed\n");
 663                 goto exit_unregister;
 664         }
 665
 666         if (rc & ISL1208_REG_SR_RTCF)
 667                 dev_warn(&client->dev, "rtc power failure detected, "
 668                          "please set clock.\n");
 669
 670         rc = sysfs_create_group(&client->dev.kobj, &isl1208_rtc_sysfs_files);
 671         if (rc)
 672                 goto exit_unregister;
 673
 674         return 0;
 675
 676 exit_unregister:
 677         rtc_device_unregister(rtc);
 678 exit_free_irq:
 679         if (client->irq)
 680                 free_irq(client->irq, client);
 681
 682         return rc;
 683 }
 684
 685 static int
 686 isl1208_remove(struct i2c_client *client)
 687 {
 688         struct rtc_device *rtc = i2c_get_clientdata(client);
 689
 690         sysfs_remove_group(&client->dev.kobj, &isl1208_rtc_sysfs_files);
 691         rtc_device_unregister(rtc);
 692         if (client->irq)
 693                 free_irq(client->irq, client);
 694
 695         return 0;
 696 }
 697
 698 static const struct i2c_device_id isl1208_id[] = {
 699         { "isl1208", 0 },
 700         { }
 701 };
 702 MODULE_DEVICE_TABLE(i2c, isl1208_id);
 703
 704 static struct i2c_driver isl1208_driver = {
 705         .driver = {
 706                    .name = "rtc-isl1208",
 707                    },
 708         .probe = isl1208_probe,
 709         .remove = isl1208_remove,
 710         .id_table = isl1208_id,
 711 };
 712
 713 static int __init
 714 isl1208_init(void)
 715 {
 716         return i2c_add_driver(&isl1208_driver);
 717 }
 718
 719 static void __exit
 720 isl1208_exit(void)
 721 {
 722         i2c_del_driver(&isl1208_driver);
 723 }
 724
 725 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
 726 MODULE_DESCRIPTION("Intersil ISL1208 RTC driver");
 727 MODULE_LICENSE("GPL");
 728 MODULE_VERSION(DRV_VERSION);
 729
 730 module_init(isl1208_init);
 731 module_exit(isl1208_exit);