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 static DEFINE_MUTEX(m41t80_rtc_mutex);
  70 static const struct i2c_device_id m41t80_id[] = {
  71         { "m41t62", M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT },
  72         { "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
  73         { "m41t80", M41T80_FEATURE_SQ },
  74         { "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
  75         { "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  76         { "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  77         { "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  78         { "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  79         { "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  80         { "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  81         { "rv4162", M41T80_FEATURE_SQ | M41T80_FEATURE_WD | M41T80_FEATURE_SQ_ALT },
  82         { }
  83 };
  84 MODULE_DEVICE_TABLE(i2c, m41t80_id);
  85
  86 struct m41t80_data {
  87         u8 features;
  88         struct rtc_device *rtc;
  89 };
  90
  91 static int m41t80_get_datetime(struct i2c_client *client,
  92                                struct rtc_time *tm)
  93 {
  94         u8 buf[M41T80_DATETIME_REG_SIZE], dt_addr[1] = { M41T80_REG_SEC };
  95         struct i2c_msg msgs[] = {
  96                 {
  97                         .addr   = client->addr,
  98                         .flags  = 0,
  99                         .len    = 1,
 100                         .buf    = dt_addr,
 101                 },
 102                 {
 103                         .addr   = client->addr,
 104                         .flags  = I2C_M_RD,
 105                         .len    = M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
 106                         .buf    = buf + M41T80_REG_SEC,
 107                 },
 108         };
 109
 110         if (i2c_transfer(client->adapter, msgs, 2) < 0) {
 111                 dev_err(&client->dev, "read error\n");
 112                 return -EIO;
 113         }
 114
 115         tm->tm_sec = bcd2bin(buf[M41T80_REG_SEC] & 0x7f);
 116         tm->tm_min = bcd2bin(buf[M41T80_REG_MIN] & 0x7f);
 117         tm->tm_hour = bcd2bin(buf[M41T80_REG_HOUR] & 0x3f);
 118         tm->tm_mday = bcd2bin(buf[M41T80_REG_DAY] & 0x3f);
 119         tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
 120         tm->tm_mon = bcd2bin(buf[M41T80_REG_MON] & 0x1f) - 1;
 121
 122         /* assume 20YY not 19YY, and ignore the Century Bit */
 123         tm->tm_year = bcd2bin(buf[M41T80_REG_YEAR]) + 100;
 124         return rtc_valid_tm(tm);
 125 }
 126
 127 /* Sets the given date and time to the real time clock. */
 128 static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 129 {
 130         u8 wbuf[1 + M41T80_DATETIME_REG_SIZE];
 131         u8 *buf = &wbuf[1];
 132         u8 dt_addr[1] = { M41T80_REG_SEC };
 133         struct i2c_msg msgs_in[] = {
 134                 {
 135                         .addr   = client->addr,
 136                         .flags  = 0,
 137                         .len    = 1,
 138                         .buf    = dt_addr,
 139                 },
 140                 {
 141                         .addr   = client->addr,
 142                         .flags  = I2C_M_RD,
 143                         .len    = M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
 144                         .buf    = buf + M41T80_REG_SEC,
 145                 },
 146         };
 147         struct i2c_msg msgs[] = {
 148                 {
 149                         .addr   = client->addr,
 150                         .flags  = 0,
 151                         .len    = 1 + M41T80_DATETIME_REG_SIZE,
 152                         .buf    = wbuf,
 153                  },
 154         };
 155
 156         /* Read current reg values into buf[1..7] */
 157         if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
 158                 dev_err(&client->dev, "read error\n");
 159                 return -EIO;
 160         }
 161
 162         wbuf[0] = 0; /* offset into rtc's regs */
 163         /* Merge time-data and register flags into buf[0..7] */
 164         buf[M41T80_REG_SSEC] = 0;
 165         buf[M41T80_REG_SEC] =
 166                 bin2bcd(tm->tm_sec) | (buf[M41T80_REG_SEC] & ~0x7f);
 167         buf[M41T80_REG_MIN] =
 168                 bin2bcd(tm->tm_min) | (buf[M41T80_REG_MIN] & ~0x7f);
 169         buf[M41T80_REG_HOUR] =
 170                 bin2bcd(tm->tm_hour) | (buf[M41T80_REG_HOUR] & ~0x3f);
 171         buf[M41T80_REG_WDAY] =
 172                 (tm->tm_wday & 0x07) | (buf[M41T80_REG_WDAY] & ~0x07);
 173         buf[M41T80_REG_DAY] =
 174                 bin2bcd(tm->tm_mday) | (buf[M41T80_REG_DAY] & ~0x3f);
 175         buf[M41T80_REG_MON] =
 176                 bin2bcd(tm->tm_mon + 1) | (buf[M41T80_REG_MON] & ~0x1f);
 177         /* assume 20YY not 19YY */
 178         buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year % 100);
 179
 180         if (i2c_transfer(client->adapter, msgs, 1) != 1) {
 181                 dev_err(&client->dev, "write error\n");
 182                 return -EIO;
 183         }
 184         return 0;
 185 }
 186
 187 #if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
 188 static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
 189 {
 190         struct i2c_client *client = to_i2c_client(dev);
 191         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 192         u8 reg;
 193
 194         if (clientdata->features & M41T80_FEATURE_BL) {
 195                 reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 196                 seq_printf(seq, "battery\t\t: %s\n",
 197                            (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
 198         }
 199         return 0;
 200 }
 201 #else
 202 #define m41t80_rtc_proc NULL
 203 #endif
 204
 205 static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
 206 {
 207         return m41t80_get_datetime(to_i2c_client(dev), tm);
 208 }
 209
 210 static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
 211 {
 212         return m41t80_set_datetime(to_i2c_client(dev), tm);
 213 }
 214
 215 /*
 216  * XXX - m41t80 alarm functionality is reported broken.
 217  * until it is fixed, don't register alarm functions.
 218  */
 219 static struct rtc_class_ops m41t80_rtc_ops = {
 220         .read_time = m41t80_rtc_read_time,
 221         .set_time = m41t80_rtc_set_time,
 222         .proc = m41t80_rtc_proc,
 223 };
 224
 225 #if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
 226 static ssize_t m41t80_sysfs_show_flags(struct device *dev,
 227                                 struct device_attribute *attr, char *buf)
 228 {
 229         struct i2c_client *client = to_i2c_client(dev);
 230         int val;
 231
 232         val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 233         if (val < 0)
 234                 return val;
 235         return sprintf(buf, "%#x\n", val);
 236 }
 237 static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
 238
 239 static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
 240                                 struct device_attribute *attr, char *buf)
 241 {
 242         struct i2c_client *client = to_i2c_client(dev);
 243         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 244         int val, reg_sqw;
 245
 246         if (!(clientdata->features & M41T80_FEATURE_SQ))
 247                 return -EINVAL;
 248
 249         reg_sqw = M41T80_REG_SQW;
 250         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 251                 reg_sqw = M41T80_REG_WDAY;
 252         val = i2c_smbus_read_byte_data(client, reg_sqw);
 253         if (val < 0)
 254                 return val;
 255         val = (val >> 4) & 0xf;
 256         switch (val) {
 257         case 0:
 258                 break;
 259         case 1:
 260                 val = 32768;
 261                 break;
 262         default:
 263                 val = 32768 >> val;
 264         }
 265         return sprintf(buf, "%d\n", val);
 266 }
 267 static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
 268                                 struct device_attribute *attr,
 269                                 const char *buf, size_t count)
 270 {
 271         struct i2c_client *client = to_i2c_client(dev);
 272         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 273         int almon, sqw, reg_sqw, rc;
 274         int val = simple_strtoul(buf, NULL, 0);
 275
 276         if (!(clientdata->features & M41T80_FEATURE_SQ))
 277                 return -EINVAL;
 278
 279         if (val) {
 280                 if (!is_power_of_2(val))
 281                         return -EINVAL;
 282                 val = ilog2(val);
 283                 if (val == 15)
 284                         val = 1;
 285                 else if (val < 14)
 286                         val = 15 - val;
 287                 else
 288                         return -EINVAL;
 289         }
 290         /* disable SQW, set SQW frequency & re-enable */
 291         almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 292         if (almon < 0)
 293                 return almon;
 294         reg_sqw = M41T80_REG_SQW;
 295         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 296                 reg_sqw = M41T80_REG_WDAY;
 297         sqw = i2c_smbus_read_byte_data(client, reg_sqw);
 298         if (sqw < 0)
 299                 return sqw;
 300         sqw = (sqw & 0x0f) | (val << 4);
 301
 302         rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 303                                       almon & ~M41T80_ALMON_SQWE);
 304         if (rc < 0)
 305                 return rc;
 306
 307         if (val) {
 308                 rc = i2c_smbus_write_byte_data(client, reg_sqw, sqw);
 309                 if (rc < 0)
 310                         return rc;
 311
 312                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 313                                              almon | M41T80_ALMON_SQWE);
 314                 if (rc <0)
 315                         return rc;
 316         }
 317         return count;
 318 }
 319 static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
 320                    m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
 321
 322 static struct attribute *attrs[] = {
 323         &dev_attr_flags.attr,
 324         &dev_attr_sqwfreq.attr,
 325         NULL,
 326 };
 327 static struct attribute_group attr_group = {
 328         .attrs = attrs,
 329 };
 330
 331 static int m41t80_sysfs_register(struct device *dev)
 332 {
 333         return sysfs_create_group(&dev->kobj, &attr_group);
 334 }
 335 #else
 336 static int m41t80_sysfs_register(struct device *dev)
 337 {
 338         return 0;
 339 }
 340 #endif
 341
 342 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 343 /*
 344  *****************************************************************************
 345  *
 346  * Watchdog Driver
 347  *
 348  *****************************************************************************
 349  */
 350 static struct i2c_client *save_client;
 351
 352 /* Default margin */
 353 #define WD_TIMO 60              /* 1..31 seconds */
 354
 355 static int wdt_margin = WD_TIMO;
 356 module_param(wdt_margin, int, 0);
 357 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 358
 359 static unsigned long wdt_is_open;
 360 static int boot_flag;
 361
 362 /**
 363  *      wdt_ping:
 364  *
 365  *      Reload counter one with the watchdog timeout. We don't bother reloading
 366  *      the cascade counter.
 367  */
 368 static void wdt_ping(void)
 369 {
 370         unsigned char i2c_data[2];
 371         struct i2c_msg msgs1[1] = {
 372                 {
 373                         .addr   = save_client->addr,
 374                         .flags  = 0,
 375                         .len    = 2,
 376                         .buf    = i2c_data,
 377                 },
 378         };
 379         struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 380
 381         i2c_data[0] = 0x09;             /* watchdog register */
 382
 383         if (wdt_margin > 31)
 384                 i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 385         else
 386                 /*
 387                  * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 388                  */
 389                 i2c_data[1] = wdt_margin<<2 | 0x82;
 390
 391         /*
 392          * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 393          * that would be an invalid resolution.
 394          */
 395         if (clientdata->features & M41T80_FEATURE_WD)
 396                 i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 397
 398         i2c_transfer(save_client->adapter, msgs1, 1);
 399 }
 400
 401 /**
 402  *      wdt_disable:
 403  *
 404  *      disables watchdog.
 405  */
 406 static void wdt_disable(void)
 407 {
 408         unsigned char i2c_data[2], i2c_buf[0x10];
 409         struct i2c_msg msgs0[2] = {
 410                 {
 411                         .addr   = save_client->addr,
 412                         .flags  = 0,
 413                         .len    = 1,
 414                         .buf    = i2c_data,
 415                 },
 416                 {
 417                         .addr   = save_client->addr,
 418                         .flags  = I2C_M_RD,
 419                         .len    = 1,
 420                         .buf    = i2c_buf,
 421                 },
 422         };
 423         struct i2c_msg msgs1[1] = {
 424                 {
 425                         .addr   = save_client->addr,
 426                         .flags  = 0,
 427                         .len    = 2,
 428                         .buf    = i2c_data,
 429                 },
 430         };
 431
 432         i2c_data[0] = 0x09;
 433         i2c_transfer(save_client->adapter, msgs0, 2);
 434
 435         i2c_data[0] = 0x09;
 436         i2c_data[1] = 0x00;
 437         i2c_transfer(save_client->adapter, msgs1, 1);
 438 }
 439
 440 /**
 441  *      wdt_write:
 442  *      @file: file handle to the watchdog
 443  *      @buf: buffer to write (unused as data does not matter here
 444  *      @count: count of bytes
 445  *      @ppos: pointer to the position to write. No seeks allowed
 446  *
 447  *      A write to a watchdog device is defined as a keepalive signal. Any
 448  *      write of data will do, as we we don't define content meaning.
 449  */
 450 static ssize_t wdt_write(struct file *file, const char __user *buf,
 451                          size_t count, loff_t *ppos)
 452 {
 453         if (count) {
 454                 wdt_ping();
 455                 return 1;
 456         }
 457         return 0;
 458 }
 459
 460 static ssize_t wdt_read(struct file *file, char __user *buf,
 461                         size_t count, loff_t *ppos)
 462 {
 463         return 0;
 464 }
 465
 466 /**
 467  *      wdt_ioctl:
 468  *      @inode: inode of the device
 469  *      @file: file handle to the device
 470  *      @cmd: watchdog command
 471  *      @arg: argument pointer
 472  *
 473  *      The watchdog API defines a common set of functions for all watchdogs
 474  *      according to their available features. We only actually usefully support
 475  *      querying capabilities and current status.
 476  */
 477 static int wdt_ioctl(struct file *file, unsigned int cmd,
 478                      unsigned long arg)
 479 {
 480         int new_margin, rv;
 481         static struct watchdog_info ident = {
 482                 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 483                         WDIOF_SETTIMEOUT,
 484                 .firmware_version = 1,
 485                 .identity = "M41T80 WTD"
 486         };
 487
 488         switch (cmd) {
 489         case WDIOC_GETSUPPORT:
 490                 return copy_to_user((struct watchdog_info __user *)arg, &ident,
 491                                     sizeof(ident)) ? -EFAULT : 0;
 492
 493         case WDIOC_GETSTATUS:
 494         case WDIOC_GETBOOTSTATUS:
 495                 return put_user(boot_flag, (int __user *)arg);
 496         case WDIOC_KEEPALIVE:
 497                 wdt_ping();
 498                 return 0;
 499         case WDIOC_SETTIMEOUT:
 500                 if (get_user(new_margin, (int __user *)arg))
 501                         return -EFAULT;
 502                 /* Arbitrary, can't find the card's limits */
 503                 if (new_margin < 1 || new_margin > 124)
 504                         return -EINVAL;
 505                 wdt_margin = new_margin;
 506                 wdt_ping();
 507                 /* Fall */
 508         case WDIOC_GETTIMEOUT:
 509                 return put_user(wdt_margin, (int __user *)arg);
 510
 511         case WDIOC_SETOPTIONS:
 512                 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 513                         return -EFAULT;
 514
 515                 if (rv & WDIOS_DISABLECARD) {
 516                         pr_info("rtc-m41t80: disable watchdog\n");
 517                         wdt_disable();
 518                 }
 519
 520                 if (rv & WDIOS_ENABLECARD) {
 521                         pr_info("rtc-m41t80: enable watchdog\n");
 522                         wdt_ping();
 523                 }
 524
 525                 return -EINVAL;
 526         }
 527         return -ENOTTY;
 528 }
 529
 530 static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 531                                unsigned long arg)
 532 {
 533         int ret;
 534
 535         mutex_lock(&m41t80_rtc_mutex);
 536         ret = wdt_ioctl(file, cmd, arg);
 537         mutex_unlock(&m41t80_rtc_mutex);
 538
 539         return ret;
 540 }
 541
 542 /**
 543  *      wdt_open:
 544  *      @inode: inode of device
 545  *      @file: file handle to device
 546  *
 547  */
 548 static int wdt_open(struct inode *inode, struct file *file)
 549 {
 550         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 551                 mutex_lock(&m41t80_rtc_mutex);
 552                 if (test_and_set_bit(0, &wdt_is_open)) {
 553                         mutex_unlock(&m41t80_rtc_mutex);
 554                         return -EBUSY;
 555                 }
 556                 /*
 557                  *      Activate
 558                  */
 559                 wdt_is_open = 1;
 560                 mutex_unlock(&m41t80_rtc_mutex);
 561                 return nonseekable_open(inode, file);
 562         }
 563         return -ENODEV;
 564 }
 565
 566 /**
 567  *      wdt_close:
 568  *      @inode: inode to board
 569  *      @file: file handle to board
 570  *
 571  */
 572 static int wdt_release(struct inode *inode, struct file *file)
 573 {
 574         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 575                 clear_bit(0, &wdt_is_open);
 576         return 0;
 577 }
 578
 579 /**
 580  *      notify_sys:
 581  *      @this: our notifier block
 582  *      @code: the event being reported
 583  *      @unused: unused
 584  *
 585  *      Our notifier is called on system shutdowns. We want to turn the card
 586  *      off at reboot otherwise the machine will reboot again during memory
 587  *      test or worse yet during the following fsck. This would suck, in fact
 588  *      trust me - if it happens it does suck.
 589  */
 590 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 591                           void *unused)
 592 {
 593         if (code == SYS_DOWN || code == SYS_HALT)
 594                 /* Disable Watchdog */
 595                 wdt_disable();
 596         return NOTIFY_DONE;
 597 }
 598
 599 static const struct file_operations wdt_fops = {
 600         .owner  = THIS_MODULE,
 601         .read   = wdt_read,
 602         .unlocked_ioctl = wdt_unlocked_ioctl,
 603         .write  = wdt_write,
 604         .open   = wdt_open,
 605         .release = wdt_release,
 606         .llseek = no_llseek,
 607 };
 608
 609 static struct miscdevice wdt_dev = {
 610         .minor = WATCHDOG_MINOR,
 611         .name = "watchdog",
 612         .fops = &wdt_fops,
 613 };
 614
 615 /*
 616  *      The WDT card needs to learn about soft shutdowns in order to
 617  *      turn the timebomb registers off.
 618  */
 619 static struct notifier_block wdt_notifier = {
 620         .notifier_call = wdt_notify_sys,
 621 };
 622 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
 623
 624 /*
 625  *****************************************************************************
 626  *
 627  *      Driver Interface
 628  *
 629  *****************************************************************************
 630  */
 631 static int m41t80_probe(struct i2c_client *client,
 632                         const struct i2c_device_id *id)
 633 {
 634         int rc = 0;
 635         struct rtc_device *rtc = NULL;
 636         struct rtc_time tm;
 637         struct m41t80_data *clientdata = NULL;
 638
 639         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
 640                                      | I2C_FUNC_SMBUS_BYTE_DATA))
 641                 return -ENODEV;
 642
 643         clientdata = devm_kzalloc(&client->dev, sizeof(*clientdata),
 644                                 GFP_KERNEL);
 645         if (!clientdata)
 646                 return -ENOMEM;
 647
 648         clientdata->features = id->driver_data;
 649         i2c_set_clientdata(client, clientdata);
 650
 651         rtc = devm_rtc_device_register(&client->dev, client->name,
 652                                         &m41t80_rtc_ops, THIS_MODULE);
 653         if (IS_ERR(rtc))
 654                 return PTR_ERR(rtc);
 655
 656         clientdata->rtc = rtc;
 657
 658         /* Make sure HT (Halt Update) bit is cleared */
 659         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 660
 661         if (rc >= 0 && rc & M41T80_ALHOUR_HT) {
 662                 if (clientdata->features & M41T80_FEATURE_HT) {
 663                         m41t80_get_datetime(client, &tm);
 664                         dev_info(&client->dev, "HT bit was set!\n");
 665                         dev_info(&client->dev,
 666                                  "Power Down at "
 667                                  "%04i-%02i-%02i %02i:%02i:%02i\n",
 668                                  tm.tm_year + 1900,
 669                                  tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
 670                                  tm.tm_min, tm.tm_sec);
 671                 }
 672                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_HOUR,
 673                                               rc & ~M41T80_ALHOUR_HT);
 674         }
 675
 676         if (rc < 0) {
 677                 dev_err(&client->dev, "Can't clear HT bit\n");
 678                 return rc;
 679         }
 680
 681         /* Make sure ST (stop) bit is cleared */
 682         rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 683
 684         if (rc >= 0 && rc & M41T80_SEC_ST)
 685                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 686                                               rc & ~M41T80_SEC_ST);
 687         if (rc < 0) {
 688                 dev_err(&client->dev, "Can't clear ST bit\n");
 689                 return rc;
 690         }
 691
 692         rc = m41t80_sysfs_register(&client->dev);
 693         if (rc)
 694                 return rc;
 695
 696 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 697         if (clientdata->features & M41T80_FEATURE_HT) {
 698                 save_client = client;
 699                 rc = misc_register(&wdt_dev);
 700                 if (rc)
 701                         return rc;
 702                 rc = register_reboot_notifier(&wdt_notifier);
 703                 if (rc) {
 704                         misc_deregister(&wdt_dev);
 705                         return rc;
 706                 }
 707         }
 708 #endif
 709         return 0;
 710 }
 711
 712 static int m41t80_remove(struct i2c_client *client)
 713 {
 714 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 715         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 716
 717         if (clientdata->features & M41T80_FEATURE_HT) {
 718                 misc_deregister(&wdt_dev);
 719                 unregister_reboot_notifier(&wdt_notifier);
 720         }
 721 #endif
 722
 723         return 0;
 724 }
 725
 726 static struct i2c_driver m41t80_driver = {
 727         .driver = {
 728                 .name = "rtc-m41t80",
 729         },
 730         .probe = m41t80_probe,
 731         .remove = m41t80_remove,
 732         .id_table = m41t80_id,
 733 };
 734
 735 module_i2c_driver(m41t80_driver);
 736
 737 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
 738 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
 739 MODULE_LICENSE("GPL");