drivers/rtc/rtc-m41t80.c

   1 /*
   2  * I2C client/driver for the ST M41T80 family of i2c rtc chips.
   3  *
   4  * Author: Alexander Bigga <ab@mycable.de>
   5  *
   6  * Based on m41t00.c by Mark A. Greer <mgreer@mvista.com>
   7  *
   8  * 2006 (c) mycable GmbH
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  *
  14  */
  15
  16 #include <linux/bcd.h>
  17 #include <linux/i2c.h>
  18 #include <linux/init.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/rtc.h>
  22 #include <linux/slab.h>
  23 #include <linux/mutex.h>
  24 #include <linux/string.h>
  25 #ifdef CONFIG_RTC_DRV_M41T80_WDT
  26 #include <linux/fs.h>
  27 #include <linux/ioctl.h>
  28 #include <linux/miscdevice.h>
  29 #include <linux/reboot.h>
  30 #include <linux/watchdog.h>
  31 #endif
  32
  33 #define M41T80_REG_SSEC 0
  34 #define M41T80_REG_SEC  1
  35 #define M41T80_REG_MIN  2
  36 #define M41T80_REG_HOUR 3
  37 #define M41T80_REG_WDAY 4
  38 #define M41T80_REG_DAY  5
  39 #define M41T80_REG_MON  6
  40 #define M41T80_REG_YEAR 7
  41 #define M41T80_REG_ALARM_MON    0xa
  42 #define M41T80_REG_ALARM_DAY    0xb
  43 #define M41T80_REG_ALARM_HOUR   0xc
  44 #define M41T80_REG_ALARM_MIN    0xd
  45 #define M41T80_REG_ALARM_SEC    0xe
  46 #define M41T80_REG_FLAGS        0xf
  47 #define M41T80_REG_SQW  0x13
  48
  49 #define M41T80_DATETIME_REG_SIZE        (M41T80_REG_YEAR + 1)
  50 #define M41T80_ALARM_REG_SIZE   \
  51         (M41T80_REG_ALARM_SEC + 1 - M41T80_REG_ALARM_MON)
  52
  53 #define M41T80_SEC_ST           (1 << 7)        /* ST: Stop Bit */
  54 #define M41T80_ALMON_AFE        (1 << 7)        /* AFE: AF Enable Bit */
  55 #define M41T80_ALMON_SQWE       (1 << 6)        /* SQWE: SQW Enable Bit */
  56 #define M41T80_ALHOUR_HT        (1 << 6)        /* HT: Halt Update Bit */
  57 #define M41T80_FLAGS_AF         (1 << 6)        /* AF: Alarm Flag Bit */
  58 #define M41T80_FLAGS_BATT_LOW   (1 << 4)        /* BL: Battery Low Bit */
  59 #define M41T80_WATCHDOG_RB2     (1 << 7)        /* RB: Watchdog resolution */
  60 #define M41T80_WATCHDOG_RB1     (1 << 1)        /* RB: Watchdog resolution */
  61 #define M41T80_WATCHDOG_RB0     (1 << 0)        /* RB: Watchdog resolution */
  62
  63 #define M41T80_FEATURE_HT       (1 << 0)        /* Halt feature */
  64 #define M41T80_FEATURE_BL       (1 << 1)        /* Battery low indicator */
  65 #define M41T80_FEATURE_SQ       (1 << 2)        /* Squarewave feature */
  66 #define M41T80_FEATURE_WD       (1 << 3)        /* Extra watchdog resolution */
  67 #define M41T80_FEATURE_SQ_ALT   (1 << 4)        /* RSx bits are in reg 4 */
  68
  69 #define DRV_VERSION "0.05"
  70
  71 static DEFINE_MUTEX(m41t80_rtc_mutex);
  72 static const struct i2c_device_id m41t80_id[] = {
  73         { "m41t62", M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT },
  74         { "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
  75         { "m41t80", M41T80_FEATURE_SQ },
  76         { "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
  77         { "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  78         { "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  79         { "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  80         { "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  81         { "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  82         { "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  83         { }
  84 };
  85 MODULE_DEVICE_TABLE(i2c, m41t80_id);
  86
  87 struct m41t80_data {
  88         u8 features;
  89         struct rtc_device *rtc;
  90 };
  91
  92 static int m41t80_get_datetime(struct i2c_client *client,
  93                                struct rtc_time *tm)
  94 {
  95         u8 buf[M41T80_DATETIME_REG_SIZE], dt_addr[1] = { M41T80_REG_SEC };
  96         struct i2c_msg msgs[] = {
  97                 {
  98                         .addr   = client->addr,
  99                         .flags  = 0,
 100                         .len    = 1,
 101                         .buf    = dt_addr,
 102                 },
 103                 {
 104                         .addr   = client->addr,
 105                         .flags  = I2C_M_RD,
 106                         .len    = M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
 107                         .buf    = buf + M41T80_REG_SEC,
 108                 },
 109         };
 110
 111         if (i2c_transfer(client->adapter, msgs, 2) < 0) {
 112                 dev_err(&client->dev, "read error\n");
 113                 return -EIO;
 114         }
 115
 116         tm->tm_sec = bcd2bin(buf[M41T80_REG_SEC] & 0x7f);
 117         tm->tm_min = bcd2bin(buf[M41T80_REG_MIN] & 0x7f);
 118         tm->tm_hour = bcd2bin(buf[M41T80_REG_HOUR] & 0x3f);
 119         tm->tm_mday = bcd2bin(buf[M41T80_REG_DAY] & 0x3f);
 120         tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
 121         tm->tm_mon = bcd2bin(buf[M41T80_REG_MON] & 0x1f) - 1;
 122
 123         /* assume 20YY not 19YY, and ignore the Century Bit */
 124         tm->tm_year = bcd2bin(buf[M41T80_REG_YEAR]) + 100;
 125         return rtc_valid_tm(tm);
 126 }
 127
 128 /* Sets the given date and time to the real time clock. */
 129 static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 130 {
 131         u8 wbuf[1 + M41T80_DATETIME_REG_SIZE];
 132         u8 *buf = &wbuf[1];
 133         u8 dt_addr[1] = { M41T80_REG_SEC };
 134         struct i2c_msg msgs_in[] = {
 135                 {
 136                         .addr   = client->addr,
 137                         .flags  = 0,
 138                         .len    = 1,
 139                         .buf    = dt_addr,
 140                 },
 141                 {
 142                         .addr   = client->addr,
 143                         .flags  = I2C_M_RD,
 144                         .len    = M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
 145                         .buf    = buf + M41T80_REG_SEC,
 146                 },
 147         };
 148         struct i2c_msg msgs[] = {
 149                 {
 150                         .addr   = client->addr,
 151                         .flags  = 0,
 152                         .len    = 1 + M41T80_DATETIME_REG_SIZE,
 153                         .buf    = wbuf,
 154                  },
 155         };
 156
 157         /* Read current reg values into buf[1..7] */
 158         if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
 159                 dev_err(&client->dev, "read error\n");
 160                 return -EIO;
 161         }
 162
 163         wbuf[0] = 0; /* offset into rtc's regs */
 164         /* Merge time-data and register flags into buf[0..7] */
 165         buf[M41T80_REG_SSEC] = 0;
 166         buf[M41T80_REG_SEC] =
 167                 bin2bcd(tm->tm_sec) | (buf[M41T80_REG_SEC] & ~0x7f);
 168         buf[M41T80_REG_MIN] =
 169                 bin2bcd(tm->tm_min) | (buf[M41T80_REG_MIN] & ~0x7f);
 170         buf[M41T80_REG_HOUR] =
 171                 bin2bcd(tm->tm_hour) | (buf[M41T80_REG_HOUR] & ~0x3f);
 172         buf[M41T80_REG_WDAY] =
 173                 (tm->tm_wday & 0x07) | (buf[M41T80_REG_WDAY] & ~0x07);
 174         buf[M41T80_REG_DAY] =
 175                 bin2bcd(tm->tm_mday) | (buf[M41T80_REG_DAY] & ~0x3f);
 176         buf[M41T80_REG_MON] =
 177                 bin2bcd(tm->tm_mon + 1) | (buf[M41T80_REG_MON] & ~0x1f);
 178         /* assume 20YY not 19YY */
 179         buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year % 100);
 180
 181         if (i2c_transfer(client->adapter, msgs, 1) != 1) {
 182                 dev_err(&client->dev, "write error\n");
 183                 return -EIO;
 184         }
 185         return 0;
 186 }
 187
 188 #if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
 189 static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
 190 {
 191         struct i2c_client *client = to_i2c_client(dev);
 192         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 193         u8 reg;
 194
 195         if (clientdata->features & M41T80_FEATURE_BL) {
 196                 reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 197                 seq_printf(seq, "battery\t\t: %s\n",
 198                            (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
 199         }
 200         return 0;
 201 }
 202 #else
 203 #define m41t80_rtc_proc NULL
 204 #endif
 205
 206 static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
 207 {
 208         return m41t80_get_datetime(to_i2c_client(dev), tm);
 209 }
 210
 211 static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
 212 {
 213         return m41t80_set_datetime(to_i2c_client(dev), tm);
 214 }
 215
 216 /*
 217  * XXX - m41t80 alarm functionality is reported broken.
 218  * until it is fixed, don't register alarm functions.
 219  */
 220 static struct rtc_class_ops m41t80_rtc_ops = {
 221         .read_time = m41t80_rtc_read_time,
 222         .set_time = m41t80_rtc_set_time,
 223         .proc = m41t80_rtc_proc,
 224 };
 225
 226 #if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
 227 static ssize_t m41t80_sysfs_show_flags(struct device *dev,
 228                                 struct device_attribute *attr, char *buf)
 229 {
 230         struct i2c_client *client = to_i2c_client(dev);
 231         int val;
 232
 233         val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 234         if (val < 0)
 235                 return -EIO;
 236         return sprintf(buf, "%#x\n", val);
 237 }
 238 static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
 239
 240 static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
 241                                 struct device_attribute *attr, char *buf)
 242 {
 243         struct i2c_client *client = to_i2c_client(dev);
 244         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 245         int val, reg_sqw;
 246
 247         if (!(clientdata->features & M41T80_FEATURE_SQ))
 248                 return -EINVAL;
 249
 250         reg_sqw = M41T80_REG_SQW;
 251         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 252                 reg_sqw = M41T80_REG_WDAY;
 253         val = i2c_smbus_read_byte_data(client, reg_sqw);
 254         if (val < 0)
 255                 return -EIO;
 256         val = (val >> 4) & 0xf;
 257         switch (val) {
 258         case 0:
 259                 break;
 260         case 1:
 261                 val = 32768;
 262                 break;
 263         default:
 264                 val = 32768 >> val;
 265         }
 266         return sprintf(buf, "%d\n", val);
 267 }
 268 static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
 269                                 struct device_attribute *attr,
 270                                 const char *buf, size_t count)
 271 {
 272         struct i2c_client *client = to_i2c_client(dev);
 273         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 274         int almon, sqw, reg_sqw;
 275         int val = simple_strtoul(buf, NULL, 0);
 276
 277         if (!(clientdata->features & M41T80_FEATURE_SQ))
 278                 return -EINVAL;
 279
 280         if (val) {
 281                 if (!is_power_of_2(val))
 282                         return -EINVAL;
 283                 val = ilog2(val);
 284                 if (val == 15)
 285                         val = 1;
 286                 else if (val < 14)
 287                         val = 15 - val;
 288                 else
 289                         return -EINVAL;
 290         }
 291         /* disable SQW, set SQW frequency & re-enable */
 292         almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 293         if (almon < 0)
 294                 return -EIO;
 295         reg_sqw = M41T80_REG_SQW;
 296         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 297                 reg_sqw = M41T80_REG_WDAY;
 298         sqw = i2c_smbus_read_byte_data(client, reg_sqw);
 299         if (sqw < 0)
 300                 return -EIO;
 301         sqw = (sqw & 0x0f) | (val << 4);
 302         if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 303                                       almon & ~M41T80_ALMON_SQWE) < 0 ||
 304             i2c_smbus_write_byte_data(client, reg_sqw, sqw) < 0)
 305                 return -EIO;
 306         if (val && i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 307                                              almon | M41T80_ALMON_SQWE) < 0)
 308                 return -EIO;
 309         return count;
 310 }
 311 static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
 312                    m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
 313
 314 static struct attribute *attrs[] = {
 315         &dev_attr_flags.attr,
 316         &dev_attr_sqwfreq.attr,
 317         NULL,
 318 };
 319 static struct attribute_group attr_group = {
 320         .attrs = attrs,
 321 };
 322
 323 static int m41t80_sysfs_register(struct device *dev)
 324 {
 325         return sysfs_create_group(&dev->kobj, &attr_group);
 326 }
 327 #else
 328 static int m41t80_sysfs_register(struct device *dev)
 329 {
 330         return 0;
 331 }
 332 #endif
 333
 334 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 335 /*
 336  *****************************************************************************
 337  *
 338  * Watchdog Driver
 339  *
 340  *****************************************************************************
 341  */
 342 static struct i2c_client *save_client;
 343
 344 /* Default margin */
 345 #define WD_TIMO 60              /* 1..31 seconds */
 346
 347 static int wdt_margin = WD_TIMO;
 348 module_param(wdt_margin, int, 0);
 349 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 350
 351 static unsigned long wdt_is_open;
 352 static int boot_flag;
 353
 354 /**
 355  *      wdt_ping:
 356  *
 357  *      Reload counter one with the watchdog timeout. We don't bother reloading
 358  *      the cascade counter.
 359  */
 360 static void wdt_ping(void)
 361 {
 362         unsigned char i2c_data[2];
 363         struct i2c_msg msgs1[1] = {
 364                 {
 365                         .addr   = save_client->addr,
 366                         .flags  = 0,
 367                         .len    = 2,
 368                         .buf    = i2c_data,
 369                 },
 370         };
 371         struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 372
 373         i2c_data[0] = 0x09;             /* watchdog register */
 374
 375         if (wdt_margin > 31)
 376                 i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 377         else
 378                 /*
 379                  * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 380                  */
 381                 i2c_data[1] = wdt_margin<<2 | 0x82;
 382
 383         /*
 384          * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 385          * that would be an invalid resolution.
 386          */
 387         if (clientdata->features & M41T80_FEATURE_WD)
 388                 i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 389
 390         i2c_transfer(save_client->adapter, msgs1, 1);
 391 }
 392
 393 /**
 394  *      wdt_disable:
 395  *
 396  *      disables watchdog.
 397  */
 398 static void wdt_disable(void)
 399 {
 400         unsigned char i2c_data[2], i2c_buf[0x10];
 401         struct i2c_msg msgs0[2] = {
 402                 {
 403                         .addr   = save_client->addr,
 404                         .flags  = 0,
 405                         .len    = 1,
 406                         .buf    = i2c_data,
 407                 },
 408                 {
 409                         .addr   = save_client->addr,
 410                         .flags  = I2C_M_RD,
 411                         .len    = 1,
 412                         .buf    = i2c_buf,
 413                 },
 414         };
 415         struct i2c_msg msgs1[1] = {
 416                 {
 417                         .addr   = save_client->addr,
 418                         .flags  = 0,
 419                         .len    = 2,
 420                         .buf    = i2c_data,
 421                 },
 422         };
 423
 424         i2c_data[0] = 0x09;
 425         i2c_transfer(save_client->adapter, msgs0, 2);
 426
 427         i2c_data[0] = 0x09;
 428         i2c_data[1] = 0x00;
 429         i2c_transfer(save_client->adapter, msgs1, 1);
 430 }
 431
 432 /**
 433  *      wdt_write:
 434  *      @file: file handle to the watchdog
 435  *      @buf: buffer to write (unused as data does not matter here
 436  *      @count: count of bytes
 437  *      @ppos: pointer to the position to write. No seeks allowed
 438  *
 439  *      A write to a watchdog device is defined as a keepalive signal. Any
 440  *      write of data will do, as we we don't define content meaning.
 441  */
 442 static ssize_t wdt_write(struct file *file, const char __user *buf,
 443                          size_t count, loff_t *ppos)
 444 {
 445         if (count) {
 446                 wdt_ping();
 447                 return 1;
 448         }
 449         return 0;
 450 }
 451
 452 static ssize_t wdt_read(struct file *file, char __user *buf,
 453                         size_t count, loff_t *ppos)
 454 {
 455         return 0;
 456 }
 457
 458 /**
 459  *      wdt_ioctl:
 460  *      @inode: inode of the device
 461  *      @file: file handle to the device
 462  *      @cmd: watchdog command
 463  *      @arg: argument pointer
 464  *
 465  *      The watchdog API defines a common set of functions for all watchdogs
 466  *      according to their available features. We only actually usefully support
 467  *      querying capabilities and current status.
 468  */
 469 static int wdt_ioctl(struct file *file, unsigned int cmd,
 470                      unsigned long arg)
 471 {
 472         int new_margin, rv;
 473         static struct watchdog_info ident = {
 474                 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 475                         WDIOF_SETTIMEOUT,
 476                 .firmware_version = 1,
 477                 .identity = "M41T80 WTD"
 478         };
 479
 480         switch (cmd) {
 481         case WDIOC_GETSUPPORT:
 482                 return copy_to_user((struct watchdog_info __user *)arg, &ident,
 483                                     sizeof(ident)) ? -EFAULT : 0;
 484
 485         case WDIOC_GETSTATUS:
 486         case WDIOC_GETBOOTSTATUS:
 487                 return put_user(boot_flag, (int __user *)arg);
 488         case WDIOC_KEEPALIVE:
 489                 wdt_ping();
 490                 return 0;
 491         case WDIOC_SETTIMEOUT:
 492                 if (get_user(new_margin, (int __user *)arg))
 493                         return -EFAULT;
 494                 /* Arbitrary, can't find the card's limits */
 495                 if (new_margin < 1 || new_margin > 124)
 496                         return -EINVAL;
 497                 wdt_margin = new_margin;
 498                 wdt_ping();
 499                 /* Fall */
 500         case WDIOC_GETTIMEOUT:
 501                 return put_user(wdt_margin, (int __user *)arg);
 502
 503         case WDIOC_SETOPTIONS:
 504                 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 505                         return -EFAULT;
 506
 507                 if (rv & WDIOS_DISABLECARD) {
 508                         pr_info("rtc-m41t80: disable watchdog\n");
 509                         wdt_disable();
 510                 }
 511
 512                 if (rv & WDIOS_ENABLECARD) {
 513                         pr_info("rtc-m41t80: enable watchdog\n");
 514                         wdt_ping();
 515                 }
 516
 517                 return -EINVAL;
 518         }
 519         return -ENOTTY;
 520 }
 521
 522 static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 523                                unsigned long arg)
 524 {
 525         int ret;
 526
 527         mutex_lock(&m41t80_rtc_mutex);
 528         ret = wdt_ioctl(file, cmd, arg);
 529         mutex_unlock(&m41t80_rtc_mutex);
 530
 531         return ret;
 532 }
 533
 534 /**
 535  *      wdt_open:
 536  *      @inode: inode of device
 537  *      @file: file handle to device
 538  *
 539  */
 540 static int wdt_open(struct inode *inode, struct file *file)
 541 {
 542         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 543                 mutex_lock(&m41t80_rtc_mutex);
 544                 if (test_and_set_bit(0, &wdt_is_open)) {
 545                         mutex_unlock(&m41t80_rtc_mutex);
 546                         return -EBUSY;
 547                 }
 548                 /*
 549                  *      Activate
 550                  */
 551                 wdt_is_open = 1;
 552                 mutex_unlock(&m41t80_rtc_mutex);
 553                 return nonseekable_open(inode, file);
 554         }
 555         return -ENODEV;
 556 }
 557
 558 /**
 559  *      wdt_close:
 560  *      @inode: inode to board
 561  *      @file: file handle to board
 562  *
 563  */
 564 static int wdt_release(struct inode *inode, struct file *file)
 565 {
 566         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 567                 clear_bit(0, &wdt_is_open);
 568         return 0;
 569 }
 570
 571 /**
 572  *      notify_sys:
 573  *      @this: our notifier block
 574  *      @code: the event being reported
 575  *      @unused: unused
 576  *
 577  *      Our notifier is called on system shutdowns. We want to turn the card
 578  *      off at reboot otherwise the machine will reboot again during memory
 579  *      test or worse yet during the following fsck. This would suck, in fact
 580  *      trust me - if it happens it does suck.
 581  */
 582 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 583                           void *unused)
 584 {
 585         if (code == SYS_DOWN || code == SYS_HALT)
 586                 /* Disable Watchdog */
 587                 wdt_disable();
 588         return NOTIFY_DONE;
 589 }
 590
 591 static const struct file_operations wdt_fops = {
 592         .owner  = THIS_MODULE,
 593         .read   = wdt_read,
 594         .unlocked_ioctl = wdt_unlocked_ioctl,
 595         .write  = wdt_write,
 596         .open   = wdt_open,
 597         .release = wdt_release,
 598         .llseek = no_llseek,
 599 };
 600
 601 static struct miscdevice wdt_dev = {
 602         .minor = WATCHDOG_MINOR,
 603         .name = "watchdog",
 604         .fops = &wdt_fops,
 605 };
 606
 607 /*
 608  *      The WDT card needs to learn about soft shutdowns in order to
 609  *      turn the timebomb registers off.
 610  */
 611 static struct notifier_block wdt_notifier = {
 612         .notifier_call = wdt_notify_sys,
 613 };
 614 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
 615
 616 /*
 617  *****************************************************************************
 618  *
 619  *      Driver Interface
 620  *
 621  *****************************************************************************
 622  */
 623 static int m41t80_probe(struct i2c_client *client,
 624                         const struct i2c_device_id *id)
 625 {
 626         int rc = 0;
 627         struct rtc_device *rtc = NULL;
 628         struct rtc_time tm;
 629         struct m41t80_data *clientdata = NULL;
 630
 631         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
 632                                      | I2C_FUNC_SMBUS_BYTE_DATA)) {
 633                 rc = -ENODEV;
 634                 goto exit;
 635         }
 636
 637         dev_info(&client->dev,
 638                  "chip found, driver version " DRV_VERSION "\n");
 639
 640         clientdata = devm_kzalloc(&client->dev, sizeof(*clientdata),
 641                                 GFP_KERNEL);
 642         if (!clientdata) {
 643                 rc = -ENOMEM;
 644                 goto exit;
 645         }
 646
 647         clientdata->features = id->driver_data;
 648         i2c_set_clientdata(client, clientdata);
 649
 650         rtc = devm_rtc_device_register(&client->dev, client->name,
 651                                         &m41t80_rtc_ops, THIS_MODULE);
 652         if (IS_ERR(rtc)) {
 653                 rc = PTR_ERR(rtc);
 654                 rtc = NULL;
 655                 goto exit;
 656         }
 657
 658         clientdata->rtc = rtc;
 659
 660         /* Make sure HT (Halt Update) bit is cleared */
 661         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 662         if (rc < 0)
 663                 goto ht_err;
 664
 665         if (rc & M41T80_ALHOUR_HT) {
 666                 if (clientdata->features & M41T80_FEATURE_HT) {
 667                         m41t80_get_datetime(client, &tm);
 668                         dev_info(&client->dev, "HT bit was set!\n");
 669                         dev_info(&client->dev,
 670                                  "Power Down at "
 671                                  "%04i-%02i-%02i %02i:%02i:%02i\n",
 672                                  tm.tm_year + 1900,
 673                                  tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
 674                                  tm.tm_min, tm.tm_sec);
 675                 }
 676                 if (i2c_smbus_write_byte_data(client,
 677                                               M41T80_REG_ALARM_HOUR,
 678                                               rc & ~M41T80_ALHOUR_HT) < 0)
 679                         goto ht_err;
 680         }
 681
 682         /* Make sure ST (stop) bit is cleared */
 683         rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 684         if (rc < 0)
 685                 goto st_err;
 686
 687         if (rc & M41T80_SEC_ST) {
 688                 if (i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 689                                               rc & ~M41T80_SEC_ST) < 0)
 690                         goto st_err;
 691         }
 692
 693         rc = m41t80_sysfs_register(&client->dev);
 694         if (rc)
 695                 goto exit;
 696
 697 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 698         if (clientdata->features & M41T80_FEATURE_HT) {
 699                 save_client = client;
 700                 rc = misc_register(&wdt_dev);
 701                 if (rc)
 702                         goto exit;
 703                 rc = register_reboot_notifier(&wdt_notifier);
 704                 if (rc) {
 705                         misc_deregister(&wdt_dev);
 706                         goto exit;
 707                 }
 708         }
 709 #endif
 710         return 0;
 711
 712 st_err:
 713         rc = -EIO;
 714         dev_err(&client->dev, "Can't clear ST bit\n");
 715         goto exit;
 716 ht_err:
 717         rc = -EIO;
 718         dev_err(&client->dev, "Can't clear HT bit\n");
 719         goto exit;
 720
 721 exit:
 722         return rc;
 723 }
 724
 725 static int m41t80_remove(struct i2c_client *client)
 726 {
 727 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 728         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 729
 730         if (clientdata->features & M41T80_FEATURE_HT) {
 731                 misc_deregister(&wdt_dev);
 732                 unregister_reboot_notifier(&wdt_notifier);
 733         }
 734 #endif
 735
 736         return 0;
 737 }
 738
 739 static struct i2c_driver m41t80_driver = {
 740         .driver = {
 741                 .name = "rtc-m41t80",
 742         },
 743         .probe = m41t80_probe,
 744         .remove = m41t80_remove,
 745         .id_table = m41t80_id,
 746 };
 747
 748 module_i2c_driver(m41t80_driver);
 749
 750 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
 751 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
 752 MODULE_LICENSE("GPL");
 753 MODULE_VERSION(DRV_VERSION);