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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  17
  18 #include <linux/bcd.h>
  19 #include <linux/i2c.h>
  20 #include <linux/init.h>
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/rtc.h>
  24 #include <linux/slab.h>
  25 #include <linux/mutex.h>
  26 #include <linux/string.h>
  27 #ifdef CONFIG_RTC_DRV_M41T80_WDT
  28 #include <linux/fs.h>
  29 #include <linux/ioctl.h>
  30 #include <linux/miscdevice.h>
  31 #include <linux/reboot.h>
  32 #include <linux/watchdog.h>
  33 #endif
  34
  35 #define M41T80_REG_SSEC 0
  36 #define M41T80_REG_SEC  1
  37 #define M41T80_REG_MIN  2
  38 #define M41T80_REG_HOUR 3
  39 #define M41T80_REG_WDAY 4
  40 #define M41T80_REG_DAY  5
  41 #define M41T80_REG_MON  6
  42 #define M41T80_REG_YEAR 7
  43 #define M41T80_REG_ALARM_MON    0xa
  44 #define M41T80_REG_ALARM_DAY    0xb
  45 #define M41T80_REG_ALARM_HOUR   0xc
  46 #define M41T80_REG_ALARM_MIN    0xd
  47 #define M41T80_REG_ALARM_SEC    0xe
  48 #define M41T80_REG_FLAGS        0xf
  49 #define M41T80_REG_SQW  0x13
  50
  51 #define M41T80_DATETIME_REG_SIZE        (M41T80_REG_YEAR + 1)
  52 #define M41T80_ALARM_REG_SIZE   \
  53         (M41T80_REG_ALARM_SEC + 1 - M41T80_REG_ALARM_MON)
  54
  55 #define M41T80_SEC_ST           (1 << 7)        /* ST: Stop Bit */
  56 #define M41T80_ALMON_AFE        (1 << 7)        /* AFE: AF Enable Bit */
  57 #define M41T80_ALMON_SQWE       (1 << 6)        /* SQWE: SQW Enable Bit */
  58 #define M41T80_ALHOUR_HT        (1 << 6)        /* HT: Halt Update Bit */
  59 #define M41T80_FLAGS_AF         (1 << 6)        /* AF: Alarm Flag Bit */
  60 #define M41T80_FLAGS_BATT_LOW   (1 << 4)        /* BL: Battery Low Bit */
  61 #define M41T80_WATCHDOG_RB2     (1 << 7)        /* RB: Watchdog resolution */
  62 #define M41T80_WATCHDOG_RB1     (1 << 1)        /* RB: Watchdog resolution */
  63 #define M41T80_WATCHDOG_RB0     (1 << 0)        /* RB: Watchdog resolution */
  64
  65 #define M41T80_FEATURE_HT       (1 << 0)        /* Halt feature */
  66 #define M41T80_FEATURE_BL       (1 << 1)        /* Battery low indicator */
  67 #define M41T80_FEATURE_SQ       (1 << 2)        /* Squarewave feature */
  68 #define M41T80_FEATURE_WD       (1 << 3)        /* Extra watchdog resolution */
  69 #define M41T80_FEATURE_SQ_ALT   (1 << 4)        /* RSx bits are in reg 4 */
  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         { "rv4162", M41T80_FEATURE_SQ | M41T80_FEATURE_WD | M41T80_FEATURE_SQ_ALT },
  84         { }
  85 };
  86 MODULE_DEVICE_TABLE(i2c, m41t80_id);
  87
  88 struct m41t80_data {
  89         u8 features;
  90         struct rtc_device *rtc;
  91 };
  92
  93 static int m41t80_get_datetime(struct i2c_client *client,
  94                                struct rtc_time *tm)
  95 {
  96         u8 buf[M41T80_DATETIME_REG_SIZE], dt_addr[1] = { M41T80_REG_SEC };
  97         struct i2c_msg msgs[] = {
  98                 {
  99                         .addr   = client->addr,
 100                         .flags  = 0,
 101                         .len    = 1,
 102                         .buf    = dt_addr,
 103                 },
 104                 {
 105                         .addr   = client->addr,
 106                         .flags  = I2C_M_RD,
 107                         .len    = M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
 108                         .buf    = buf + M41T80_REG_SEC,
 109                 },
 110         };
 111
 112         if (i2c_transfer(client->adapter, msgs, 2) < 0) {
 113                 dev_err(&client->dev, "read error\n");
 114                 return -EIO;
 115         }
 116
 117         tm->tm_sec = bcd2bin(buf[M41T80_REG_SEC] & 0x7f);
 118         tm->tm_min = bcd2bin(buf[M41T80_REG_MIN] & 0x7f);
 119         tm->tm_hour = bcd2bin(buf[M41T80_REG_HOUR] & 0x3f);
 120         tm->tm_mday = bcd2bin(buf[M41T80_REG_DAY] & 0x3f);
 121         tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
 122         tm->tm_mon = bcd2bin(buf[M41T80_REG_MON] & 0x1f) - 1;
 123
 124         /* assume 20YY not 19YY, and ignore the Century Bit */
 125         tm->tm_year = bcd2bin(buf[M41T80_REG_YEAR]) + 100;
 126         return rtc_valid_tm(tm);
 127 }
 128
 129 /* Sets the given date and time to the real time clock. */
 130 static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 131 {
 132         u8 wbuf[1 + M41T80_DATETIME_REG_SIZE];
 133         u8 *buf = &wbuf[1];
 134         u8 dt_addr[1] = { M41T80_REG_SEC };
 135         struct i2c_msg msgs_in[] = {
 136                 {
 137                         .addr   = client->addr,
 138                         .flags  = 0,
 139                         .len    = 1,
 140                         .buf    = dt_addr,
 141                 },
 142                 {
 143                         .addr   = client->addr,
 144                         .flags  = I2C_M_RD,
 145                         .len    = M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
 146                         .buf    = buf + M41T80_REG_SEC,
 147                 },
 148         };
 149         struct i2c_msg msgs[] = {
 150                 {
 151                         .addr   = client->addr,
 152                         .flags  = 0,
 153                         .len    = 1 + M41T80_DATETIME_REG_SIZE,
 154                         .buf    = wbuf,
 155                  },
 156         };
 157
 158         /* Read current reg values into buf[1..7] */
 159         if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
 160                 dev_err(&client->dev, "read error\n");
 161                 return -EIO;
 162         }
 163
 164         wbuf[0] = 0; /* offset into rtc's regs */
 165         /* Merge time-data and register flags into buf[0..7] */
 166         buf[M41T80_REG_SSEC] = 0;
 167         buf[M41T80_REG_SEC] =
 168                 bin2bcd(tm->tm_sec) | (buf[M41T80_REG_SEC] & ~0x7f);
 169         buf[M41T80_REG_MIN] =
 170                 bin2bcd(tm->tm_min) | (buf[M41T80_REG_MIN] & ~0x7f);
 171         buf[M41T80_REG_HOUR] =
 172                 bin2bcd(tm->tm_hour) | (buf[M41T80_REG_HOUR] & ~0x3f);
 173         buf[M41T80_REG_WDAY] =
 174                 (tm->tm_wday & 0x07) | (buf[M41T80_REG_WDAY] & ~0x07);
 175         buf[M41T80_REG_DAY] =
 176                 bin2bcd(tm->tm_mday) | (buf[M41T80_REG_DAY] & ~0x3f);
 177         buf[M41T80_REG_MON] =
 178                 bin2bcd(tm->tm_mon + 1) | (buf[M41T80_REG_MON] & ~0x1f);
 179         /* assume 20YY not 19YY */
 180         buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year % 100);
 181
 182         if (i2c_transfer(client->adapter, msgs, 1) != 1) {
 183                 dev_err(&client->dev, "write error\n");
 184                 return -EIO;
 185         }
 186         return 0;
 187 }
 188
 189 #if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
 190 static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
 191 {
 192         struct i2c_client *client = to_i2c_client(dev);
 193         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 194         u8 reg;
 195
 196         if (clientdata->features & M41T80_FEATURE_BL) {
 197                 reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 198                 seq_printf(seq, "battery\t\t: %s\n",
 199                            (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
 200         }
 201         return 0;
 202 }
 203 #else
 204 #define m41t80_rtc_proc NULL
 205 #endif
 206
 207 static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
 208 {
 209         return m41t80_get_datetime(to_i2c_client(dev), tm);
 210 }
 211
 212 static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
 213 {
 214         return m41t80_set_datetime(to_i2c_client(dev), tm);
 215 }
 216
 217 /*
 218  * XXX - m41t80 alarm functionality is reported broken.
 219  * until it is fixed, don't register alarm functions.
 220  */
 221 static struct rtc_class_ops m41t80_rtc_ops = {
 222         .read_time = m41t80_rtc_read_time,
 223         .set_time = m41t80_rtc_set_time,
 224         .proc = m41t80_rtc_proc,
 225 };
 226
 227 #if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
 228 static ssize_t m41t80_sysfs_show_flags(struct device *dev,
 229                                 struct device_attribute *attr, char *buf)
 230 {
 231         struct i2c_client *client = to_i2c_client(dev);
 232         int val;
 233
 234         val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 235         if (val < 0)
 236                 return val;
 237         return sprintf(buf, "%#x\n", val);
 238 }
 239 static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
 240
 241 static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
 242                                 struct device_attribute *attr, char *buf)
 243 {
 244         struct i2c_client *client = to_i2c_client(dev);
 245         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 246         int val, reg_sqw;
 247
 248         if (!(clientdata->features & M41T80_FEATURE_SQ))
 249                 return -EINVAL;
 250
 251         reg_sqw = M41T80_REG_SQW;
 252         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 253                 reg_sqw = M41T80_REG_WDAY;
 254         val = i2c_smbus_read_byte_data(client, reg_sqw);
 255         if (val < 0)
 256                 return val;
 257         val = (val >> 4) & 0xf;
 258         switch (val) {
 259         case 0:
 260                 break;
 261         case 1:
 262                 val = 32768;
 263                 break;
 264         default:
 265                 val = 32768 >> val;
 266         }
 267         return sprintf(buf, "%d\n", val);
 268 }
 269 static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
 270                                 struct device_attribute *attr,
 271                                 const char *buf, size_t count)
 272 {
 273         struct i2c_client *client = to_i2c_client(dev);
 274         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 275         int almon, sqw, reg_sqw, rc;
 276         int val = simple_strtoul(buf, NULL, 0);
 277
 278         if (!(clientdata->features & M41T80_FEATURE_SQ))
 279                 return -EINVAL;
 280
 281         if (val) {
 282                 if (!is_power_of_2(val))
 283                         return -EINVAL;
 284                 val = ilog2(val);
 285                 if (val == 15)
 286                         val = 1;
 287                 else if (val < 14)
 288                         val = 15 - val;
 289                 else
 290                         return -EINVAL;
 291         }
 292         /* disable SQW, set SQW frequency & re-enable */
 293         almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 294         if (almon < 0)
 295                 return almon;
 296         reg_sqw = M41T80_REG_SQW;
 297         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 298                 reg_sqw = M41T80_REG_WDAY;
 299         sqw = i2c_smbus_read_byte_data(client, reg_sqw);
 300         if (sqw < 0)
 301                 return sqw;
 302         sqw = (sqw & 0x0f) | (val << 4);
 303
 304         rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 305                                       almon & ~M41T80_ALMON_SQWE);
 306         if (rc < 0)
 307                 return rc;
 308
 309         if (val) {
 310                 rc = i2c_smbus_write_byte_data(client, reg_sqw, sqw);
 311                 if (rc < 0)
 312                         return rc;
 313
 314                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 315                                              almon | M41T80_ALMON_SQWE);
 316                 if (rc <0)
 317                         return rc;
 318         }
 319         return count;
 320 }
 321 static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
 322                    m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
 323
 324 static struct attribute *attrs[] = {
 325         &dev_attr_flags.attr,
 326         &dev_attr_sqwfreq.attr,
 327         NULL,
 328 };
 329 static struct attribute_group attr_group = {
 330         .attrs = attrs,
 331 };
 332
 333 static int m41t80_sysfs_register(struct device *dev)
 334 {
 335         return sysfs_create_group(&dev->kobj, &attr_group);
 336 }
 337 #else
 338 static int m41t80_sysfs_register(struct device *dev)
 339 {
 340         return 0;
 341 }
 342 #endif
 343
 344 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 345 /*
 346  *****************************************************************************
 347  *
 348  * Watchdog Driver
 349  *
 350  *****************************************************************************
 351  */
 352 static struct i2c_client *save_client;
 353
 354 /* Default margin */
 355 #define WD_TIMO 60              /* 1..31 seconds */
 356
 357 static int wdt_margin = WD_TIMO;
 358 module_param(wdt_margin, int, 0);
 359 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 360
 361 static unsigned long wdt_is_open;
 362 static int boot_flag;
 363
 364 /**
 365  *      wdt_ping:
 366  *
 367  *      Reload counter one with the watchdog timeout. We don't bother reloading
 368  *      the cascade counter.
 369  */
 370 static void wdt_ping(void)
 371 {
 372         unsigned char i2c_data[2];
 373         struct i2c_msg msgs1[1] = {
 374                 {
 375                         .addr   = save_client->addr,
 376                         .flags  = 0,
 377                         .len    = 2,
 378                         .buf    = i2c_data,
 379                 },
 380         };
 381         struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 382
 383         i2c_data[0] = 0x09;             /* watchdog register */
 384
 385         if (wdt_margin > 31)
 386                 i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 387         else
 388                 /*
 389                  * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 390                  */
 391                 i2c_data[1] = wdt_margin<<2 | 0x82;
 392
 393         /*
 394          * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 395          * that would be an invalid resolution.
 396          */
 397         if (clientdata->features & M41T80_FEATURE_WD)
 398                 i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 399
 400         i2c_transfer(save_client->adapter, msgs1, 1);
 401 }
 402
 403 /**
 404  *      wdt_disable:
 405  *
 406  *      disables watchdog.
 407  */
 408 static void wdt_disable(void)
 409 {
 410         unsigned char i2c_data[2], i2c_buf[0x10];
 411         struct i2c_msg msgs0[2] = {
 412                 {
 413                         .addr   = save_client->addr,
 414                         .flags  = 0,
 415                         .len    = 1,
 416                         .buf    = i2c_data,
 417                 },
 418                 {
 419                         .addr   = save_client->addr,
 420                         .flags  = I2C_M_RD,
 421                         .len    = 1,
 422                         .buf    = i2c_buf,
 423                 },
 424         };
 425         struct i2c_msg msgs1[1] = {
 426                 {
 427                         .addr   = save_client->addr,
 428                         .flags  = 0,
 429                         .len    = 2,
 430                         .buf    = i2c_data,
 431                 },
 432         };
 433
 434         i2c_data[0] = 0x09;
 435         i2c_transfer(save_client->adapter, msgs0, 2);
 436
 437         i2c_data[0] = 0x09;
 438         i2c_data[1] = 0x00;
 439         i2c_transfer(save_client->adapter, msgs1, 1);
 440 }
 441
 442 /**
 443  *      wdt_write:
 444  *      @file: file handle to the watchdog
 445  *      @buf: buffer to write (unused as data does not matter here
 446  *      @count: count of bytes
 447  *      @ppos: pointer to the position to write. No seeks allowed
 448  *
 449  *      A write to a watchdog device is defined as a keepalive signal. Any
 450  *      write of data will do, as we we don't define content meaning.
 451  */
 452 static ssize_t wdt_write(struct file *file, const char __user *buf,
 453                          size_t count, loff_t *ppos)
 454 {
 455         if (count) {
 456                 wdt_ping();
 457                 return 1;
 458         }
 459         return 0;
 460 }
 461
 462 static ssize_t wdt_read(struct file *file, char __user *buf,
 463                         size_t count, loff_t *ppos)
 464 {
 465         return 0;
 466 }
 467
 468 /**
 469  *      wdt_ioctl:
 470  *      @inode: inode of the device
 471  *      @file: file handle to the device
 472  *      @cmd: watchdog command
 473  *      @arg: argument pointer
 474  *
 475  *      The watchdog API defines a common set of functions for all watchdogs
 476  *      according to their available features. We only actually usefully support
 477  *      querying capabilities and current status.
 478  */
 479 static int wdt_ioctl(struct file *file, unsigned int cmd,
 480                      unsigned long arg)
 481 {
 482         int new_margin, rv;
 483         static struct watchdog_info ident = {
 484                 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 485                         WDIOF_SETTIMEOUT,
 486                 .firmware_version = 1,
 487                 .identity = "M41T80 WTD"
 488         };
 489
 490         switch (cmd) {
 491         case WDIOC_GETSUPPORT:
 492                 return copy_to_user((struct watchdog_info __user *)arg, &ident,
 493                                     sizeof(ident)) ? -EFAULT : 0;
 494
 495         case WDIOC_GETSTATUS:
 496         case WDIOC_GETBOOTSTATUS:
 497                 return put_user(boot_flag, (int __user *)arg);
 498         case WDIOC_KEEPALIVE:
 499                 wdt_ping();
 500                 return 0;
 501         case WDIOC_SETTIMEOUT:
 502                 if (get_user(new_margin, (int __user *)arg))
 503                         return -EFAULT;
 504                 /* Arbitrary, can't find the card's limits */
 505                 if (new_margin < 1 || new_margin > 124)
 506                         return -EINVAL;
 507                 wdt_margin = new_margin;
 508                 wdt_ping();
 509                 /* Fall */
 510         case WDIOC_GETTIMEOUT:
 511                 return put_user(wdt_margin, (int __user *)arg);
 512
 513         case WDIOC_SETOPTIONS:
 514                 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 515                         return -EFAULT;
 516
 517                 if (rv & WDIOS_DISABLECARD) {
 518                         pr_info("disable watchdog\n");
 519                         wdt_disable();
 520                 }
 521
 522                 if (rv & WDIOS_ENABLECARD) {
 523                         pr_info("enable watchdog\n");
 524                         wdt_ping();
 525                 }
 526
 527                 return -EINVAL;
 528         }
 529         return -ENOTTY;
 530 }
 531
 532 static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 533                                unsigned long arg)
 534 {
 535         int ret;
 536
 537         mutex_lock(&m41t80_rtc_mutex);
 538         ret = wdt_ioctl(file, cmd, arg);
 539         mutex_unlock(&m41t80_rtc_mutex);
 540
 541         return ret;
 542 }
 543
 544 /**
 545  *      wdt_open:
 546  *      @inode: inode of device
 547  *      @file: file handle to device
 548  *
 549  */
 550 static int wdt_open(struct inode *inode, struct file *file)
 551 {
 552         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 553                 mutex_lock(&m41t80_rtc_mutex);
 554                 if (test_and_set_bit(0, &wdt_is_open)) {
 555                         mutex_unlock(&m41t80_rtc_mutex);
 556                         return -EBUSY;
 557                 }
 558                 /*
 559                  *      Activate
 560                  */
 561                 wdt_is_open = 1;
 562                 mutex_unlock(&m41t80_rtc_mutex);
 563                 return nonseekable_open(inode, file);
 564         }
 565         return -ENODEV;
 566 }
 567
 568 /**
 569  *      wdt_close:
 570  *      @inode: inode to board
 571  *      @file: file handle to board
 572  *
 573  */
 574 static int wdt_release(struct inode *inode, struct file *file)
 575 {
 576         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 577                 clear_bit(0, &wdt_is_open);
 578         return 0;
 579 }
 580
 581 /**
 582  *      notify_sys:
 583  *      @this: our notifier block
 584  *      @code: the event being reported
 585  *      @unused: unused
 586  *
 587  *      Our notifier is called on system shutdowns. We want to turn the card
 588  *      off at reboot otherwise the machine will reboot again during memory
 589  *      test or worse yet during the following fsck. This would suck, in fact
 590  *      trust me - if it happens it does suck.
 591  */
 592 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 593                           void *unused)
 594 {
 595         if (code == SYS_DOWN || code == SYS_HALT)
 596                 /* Disable Watchdog */
 597                 wdt_disable();
 598         return NOTIFY_DONE;
 599 }
 600
 601 static const struct file_operations wdt_fops = {
 602         .owner  = THIS_MODULE,
 603         .read   = wdt_read,
 604         .unlocked_ioctl = wdt_unlocked_ioctl,
 605         .write  = wdt_write,
 606         .open   = wdt_open,
 607         .release = wdt_release,
 608         .llseek = no_llseek,
 609 };
 610
 611 static struct miscdevice wdt_dev = {
 612         .minor = WATCHDOG_MINOR,
 613         .name = "watchdog",
 614         .fops = &wdt_fops,
 615 };
 616
 617 /*
 618  *      The WDT card needs to learn about soft shutdowns in order to
 619  *      turn the timebomb registers off.
 620  */
 621 static struct notifier_block wdt_notifier = {
 622         .notifier_call = wdt_notify_sys,
 623 };
 624 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
 625
 626 /*
 627  *****************************************************************************
 628  *
 629  *      Driver Interface
 630  *
 631  *****************************************************************************
 632  */
 633 static int m41t80_probe(struct i2c_client *client,
 634                         const struct i2c_device_id *id)
 635 {
 636         int rc = 0;
 637         struct rtc_device *rtc = NULL;
 638         struct rtc_time tm;
 639         struct m41t80_data *clientdata = NULL;
 640
 641         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
 642                                      | I2C_FUNC_SMBUS_BYTE_DATA))
 643                 return -ENODEV;
 644
 645         clientdata = devm_kzalloc(&client->dev, sizeof(*clientdata),
 646                                 GFP_KERNEL);
 647         if (!clientdata)
 648                 return -ENOMEM;
 649
 650         clientdata->features = id->driver_data;
 651         i2c_set_clientdata(client, clientdata);
 652
 653         rtc = devm_rtc_device_register(&client->dev, client->name,
 654                                         &m41t80_rtc_ops, THIS_MODULE);
 655         if (IS_ERR(rtc))
 656                 return PTR_ERR(rtc);
 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
 663         if (rc >= 0 && rc & M41T80_ALHOUR_HT) {
 664                 if (clientdata->features & M41T80_FEATURE_HT) {
 665                         m41t80_get_datetime(client, &tm);
 666                         dev_info(&client->dev, "HT bit was set!\n");
 667                         dev_info(&client->dev,
 668                                  "Power Down at "
 669                                  "%04i-%02i-%02i %02i:%02i:%02i\n",
 670                                  tm.tm_year + 1900,
 671                                  tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
 672                                  tm.tm_min, tm.tm_sec);
 673                 }
 674                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_HOUR,
 675                                               rc & ~M41T80_ALHOUR_HT);
 676         }
 677
 678         if (rc < 0) {
 679                 dev_err(&client->dev, "Can't clear HT bit\n");
 680                 return rc;
 681         }
 682
 683         /* Make sure ST (stop) bit is cleared */
 684         rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 685
 686         if (rc >= 0 && rc & M41T80_SEC_ST)
 687                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 688                                               rc & ~M41T80_SEC_ST);
 689         if (rc < 0) {
 690                 dev_err(&client->dev, "Can't clear ST bit\n");
 691                 return rc;
 692         }
 693
 694         rc = m41t80_sysfs_register(&client->dev);
 695         if (rc)
 696                 return rc;
 697
 698 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 699         if (clientdata->features & M41T80_FEATURE_HT) {
 700                 save_client = client;
 701                 rc = misc_register(&wdt_dev);
 702                 if (rc)
 703                         return rc;
 704                 rc = register_reboot_notifier(&wdt_notifier);
 705                 if (rc) {
 706                         misc_deregister(&wdt_dev);
 707                         return rc;
 708                 }
 709         }
 710 #endif
 711         return 0;
 712 }
 713
 714 static int m41t80_remove(struct i2c_client *client)
 715 {
 716 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 717         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 718
 719         if (clientdata->features & M41T80_FEATURE_HT) {
 720                 misc_deregister(&wdt_dev);
 721                 unregister_reboot_notifier(&wdt_notifier);
 722         }
 723 #endif
 724
 725         return 0;
 726 }
 727
 728 static struct i2c_driver m41t80_driver = {
 729         .driver = {
 730                 .name = "rtc-m41t80",
 731         },
 732         .probe = m41t80_probe,
 733         .remove = m41t80_remove,
 734         .id_table = m41t80_id,
 735 };
 736
 737 module_i2c_driver(m41t80_driver);
 738
 739 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
 740 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
 741 MODULE_LICENSE("GPL");