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
 180         /* assume 20YY not 19YY */
 181         if (tm->tm_year < 100 || tm->tm_year > 199) {
 182                 dev_err(&client->dev, "Year must be between 2000 and 2099. It's %d.\n",
 183                         tm->tm_year + 1900);
 184                 return -EINVAL;
 185         }
 186         buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year % 100);
 187
 188         if (i2c_transfer(client->adapter, msgs, 1) != 1) {
 189                 dev_err(&client->dev, "write error\n");
 190                 return -EIO;
 191         }
 192         return 0;
 193 }
 194
 195 #if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
 196 static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
 197 {
 198         struct i2c_client *client = to_i2c_client(dev);
 199         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 200         u8 reg;
 201
 202         if (clientdata->features & M41T80_FEATURE_BL) {
 203                 reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 204                 seq_printf(seq, "battery\t\t: %s\n",
 205                            (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
 206         }
 207         return 0;
 208 }
 209 #else
 210 #define m41t80_rtc_proc NULL
 211 #endif
 212
 213 static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
 214 {
 215         return m41t80_get_datetime(to_i2c_client(dev), tm);
 216 }
 217
 218 static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
 219 {
 220         return m41t80_set_datetime(to_i2c_client(dev), tm);
 221 }
 222
 223 /*
 224  * XXX - m41t80 alarm functionality is reported broken.
 225  * until it is fixed, don't register alarm functions.
 226  */
 227 static struct rtc_class_ops m41t80_rtc_ops = {
 228         .read_time = m41t80_rtc_read_time,
 229         .set_time = m41t80_rtc_set_time,
 230         .proc = m41t80_rtc_proc,
 231 };
 232
 233 #if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
 234 static ssize_t m41t80_sysfs_show_flags(struct device *dev,
 235                                 struct device_attribute *attr, char *buf)
 236 {
 237         struct i2c_client *client = to_i2c_client(dev);
 238         int val;
 239
 240         val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 241         if (val < 0)
 242                 return val;
 243         return sprintf(buf, "%#x\n", val);
 244 }
 245 static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
 246
 247 static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
 248                                 struct device_attribute *attr, char *buf)
 249 {
 250         struct i2c_client *client = to_i2c_client(dev);
 251         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 252         int val, reg_sqw;
 253
 254         if (!(clientdata->features & M41T80_FEATURE_SQ))
 255                 return -EINVAL;
 256
 257         reg_sqw = M41T80_REG_SQW;
 258         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 259                 reg_sqw = M41T80_REG_WDAY;
 260         val = i2c_smbus_read_byte_data(client, reg_sqw);
 261         if (val < 0)
 262                 return val;
 263         val = (val >> 4) & 0xf;
 264         switch (val) {
 265         case 0:
 266                 break;
 267         case 1:
 268                 val = 32768;
 269                 break;
 270         default:
 271                 val = 32768 >> val;
 272         }
 273         return sprintf(buf, "%d\n", val);
 274 }
 275 static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
 276                                 struct device_attribute *attr,
 277                                 const char *buf, size_t count)
 278 {
 279         struct i2c_client *client = to_i2c_client(dev);
 280         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 281         int almon, sqw, reg_sqw, rc;
 282         int val = simple_strtoul(buf, NULL, 0);
 283
 284         if (!(clientdata->features & M41T80_FEATURE_SQ))
 285                 return -EINVAL;
 286
 287         if (val) {
 288                 if (!is_power_of_2(val))
 289                         return -EINVAL;
 290                 val = ilog2(val);
 291                 if (val == 15)
 292                         val = 1;
 293                 else if (val < 14)
 294                         val = 15 - val;
 295                 else
 296                         return -EINVAL;
 297         }
 298         /* disable SQW, set SQW frequency & re-enable */
 299         almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 300         if (almon < 0)
 301                 return almon;
 302         reg_sqw = M41T80_REG_SQW;
 303         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 304                 reg_sqw = M41T80_REG_WDAY;
 305         sqw = i2c_smbus_read_byte_data(client, reg_sqw);
 306         if (sqw < 0)
 307                 return sqw;
 308         sqw = (sqw & 0x0f) | (val << 4);
 309
 310         rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 311                                       almon & ~M41T80_ALMON_SQWE);
 312         if (rc < 0)
 313                 return rc;
 314
 315         if (val) {
 316                 rc = i2c_smbus_write_byte_data(client, reg_sqw, sqw);
 317                 if (rc < 0)
 318                         return rc;
 319
 320                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 321                                              almon | M41T80_ALMON_SQWE);
 322                 if (rc <0)
 323                         return rc;
 324         }
 325         return count;
 326 }
 327 static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
 328                    m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
 329
 330 static struct attribute *attrs[] = {
 331         &dev_attr_flags.attr,
 332         &dev_attr_sqwfreq.attr,
 333         NULL,
 334 };
 335 static struct attribute_group attr_group = {
 336         .attrs = attrs,
 337 };
 338
 339 static int m41t80_sysfs_register(struct device *dev)
 340 {
 341         return sysfs_create_group(&dev->kobj, &attr_group);
 342 }
 343 #else
 344 static int m41t80_sysfs_register(struct device *dev)
 345 {
 346         return 0;
 347 }
 348 #endif
 349
 350 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 351 /*
 352  *****************************************************************************
 353  *
 354  * Watchdog Driver
 355  *
 356  *****************************************************************************
 357  */
 358 static struct i2c_client *save_client;
 359
 360 /* Default margin */
 361 #define WD_TIMO 60              /* 1..31 seconds */
 362
 363 static int wdt_margin = WD_TIMO;
 364 module_param(wdt_margin, int, 0);
 365 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 366
 367 static unsigned long wdt_is_open;
 368 static int boot_flag;
 369
 370 /**
 371  *      wdt_ping:
 372  *
 373  *      Reload counter one with the watchdog timeout. We don't bother reloading
 374  *      the cascade counter.
 375  */
 376 static void wdt_ping(void)
 377 {
 378         unsigned char i2c_data[2];
 379         struct i2c_msg msgs1[1] = {
 380                 {
 381                         .addr   = save_client->addr,
 382                         .flags  = 0,
 383                         .len    = 2,
 384                         .buf    = i2c_data,
 385                 },
 386         };
 387         struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 388
 389         i2c_data[0] = 0x09;             /* watchdog register */
 390
 391         if (wdt_margin > 31)
 392                 i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 393         else
 394                 /*
 395                  * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 396                  */
 397                 i2c_data[1] = wdt_margin<<2 | 0x82;
 398
 399         /*
 400          * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 401          * that would be an invalid resolution.
 402          */
 403         if (clientdata->features & M41T80_FEATURE_WD)
 404                 i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 405
 406         i2c_transfer(save_client->adapter, msgs1, 1);
 407 }
 408
 409 /**
 410  *      wdt_disable:
 411  *
 412  *      disables watchdog.
 413  */
 414 static void wdt_disable(void)
 415 {
 416         unsigned char i2c_data[2], i2c_buf[0x10];
 417         struct i2c_msg msgs0[2] = {
 418                 {
 419                         .addr   = save_client->addr,
 420                         .flags  = 0,
 421                         .len    = 1,
 422                         .buf    = i2c_data,
 423                 },
 424                 {
 425                         .addr   = save_client->addr,
 426                         .flags  = I2C_M_RD,
 427                         .len    = 1,
 428                         .buf    = i2c_buf,
 429                 },
 430         };
 431         struct i2c_msg msgs1[1] = {
 432                 {
 433                         .addr   = save_client->addr,
 434                         .flags  = 0,
 435                         .len    = 2,
 436                         .buf    = i2c_data,
 437                 },
 438         };
 439
 440         i2c_data[0] = 0x09;
 441         i2c_transfer(save_client->adapter, msgs0, 2);
 442
 443         i2c_data[0] = 0x09;
 444         i2c_data[1] = 0x00;
 445         i2c_transfer(save_client->adapter, msgs1, 1);
 446 }
 447
 448 /**
 449  *      wdt_write:
 450  *      @file: file handle to the watchdog
 451  *      @buf: buffer to write (unused as data does not matter here
 452  *      @count: count of bytes
 453  *      @ppos: pointer to the position to write. No seeks allowed
 454  *
 455  *      A write to a watchdog device is defined as a keepalive signal. Any
 456  *      write of data will do, as we we don't define content meaning.
 457  */
 458 static ssize_t wdt_write(struct file *file, const char __user *buf,
 459                          size_t count, loff_t *ppos)
 460 {
 461         if (count) {
 462                 wdt_ping();
 463                 return 1;
 464         }
 465         return 0;
 466 }
 467
 468 static ssize_t wdt_read(struct file *file, char __user *buf,
 469                         size_t count, loff_t *ppos)
 470 {
 471         return 0;
 472 }
 473
 474 /**
 475  *      wdt_ioctl:
 476  *      @inode: inode of the device
 477  *      @file: file handle to the device
 478  *      @cmd: watchdog command
 479  *      @arg: argument pointer
 480  *
 481  *      The watchdog API defines a common set of functions for all watchdogs
 482  *      according to their available features. We only actually usefully support
 483  *      querying capabilities and current status.
 484  */
 485 static int wdt_ioctl(struct file *file, unsigned int cmd,
 486                      unsigned long arg)
 487 {
 488         int new_margin, rv;
 489         static struct watchdog_info ident = {
 490                 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 491                         WDIOF_SETTIMEOUT,
 492                 .firmware_version = 1,
 493                 .identity = "M41T80 WTD"
 494         };
 495
 496         switch (cmd) {
 497         case WDIOC_GETSUPPORT:
 498                 return copy_to_user((struct watchdog_info __user *)arg, &ident,
 499                                     sizeof(ident)) ? -EFAULT : 0;
 500
 501         case WDIOC_GETSTATUS:
 502         case WDIOC_GETBOOTSTATUS:
 503                 return put_user(boot_flag, (int __user *)arg);
 504         case WDIOC_KEEPALIVE:
 505                 wdt_ping();
 506                 return 0;
 507         case WDIOC_SETTIMEOUT:
 508                 if (get_user(new_margin, (int __user *)arg))
 509                         return -EFAULT;
 510                 /* Arbitrary, can't find the card's limits */
 511                 if (new_margin < 1 || new_margin > 124)
 512                         return -EINVAL;
 513                 wdt_margin = new_margin;
 514                 wdt_ping();
 515                 /* Fall */
 516         case WDIOC_GETTIMEOUT:
 517                 return put_user(wdt_margin, (int __user *)arg);
 518
 519         case WDIOC_SETOPTIONS:
 520                 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 521                         return -EFAULT;
 522
 523                 if (rv & WDIOS_DISABLECARD) {
 524                         pr_info("disable watchdog\n");
 525                         wdt_disable();
 526                 }
 527
 528                 if (rv & WDIOS_ENABLECARD) {
 529                         pr_info("enable watchdog\n");
 530                         wdt_ping();
 531                 }
 532
 533                 return -EINVAL;
 534         }
 535         return -ENOTTY;
 536 }
 537
 538 static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 539                                unsigned long arg)
 540 {
 541         int ret;
 542
 543         mutex_lock(&m41t80_rtc_mutex);
 544         ret = wdt_ioctl(file, cmd, arg);
 545         mutex_unlock(&m41t80_rtc_mutex);
 546
 547         return ret;
 548 }
 549
 550 /**
 551  *      wdt_open:
 552  *      @inode: inode of device
 553  *      @file: file handle to device
 554  *
 555  */
 556 static int wdt_open(struct inode *inode, struct file *file)
 557 {
 558         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 559                 mutex_lock(&m41t80_rtc_mutex);
 560                 if (test_and_set_bit(0, &wdt_is_open)) {
 561                         mutex_unlock(&m41t80_rtc_mutex);
 562                         return -EBUSY;
 563                 }
 564                 /*
 565                  *      Activate
 566                  */
 567                 wdt_is_open = 1;
 568                 mutex_unlock(&m41t80_rtc_mutex);
 569                 return nonseekable_open(inode, file);
 570         }
 571         return -ENODEV;
 572 }
 573
 574 /**
 575  *      wdt_close:
 576  *      @inode: inode to board
 577  *      @file: file handle to board
 578  *
 579  */
 580 static int wdt_release(struct inode *inode, struct file *file)
 581 {
 582         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 583                 clear_bit(0, &wdt_is_open);
 584         return 0;
 585 }
 586
 587 /**
 588  *      notify_sys:
 589  *      @this: our notifier block
 590  *      @code: the event being reported
 591  *      @unused: unused
 592  *
 593  *      Our notifier is called on system shutdowns. We want to turn the card
 594  *      off at reboot otherwise the machine will reboot again during memory
 595  *      test or worse yet during the following fsck. This would suck, in fact
 596  *      trust me - if it happens it does suck.
 597  */
 598 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 599                           void *unused)
 600 {
 601         if (code == SYS_DOWN || code == SYS_HALT)
 602                 /* Disable Watchdog */
 603                 wdt_disable();
 604         return NOTIFY_DONE;
 605 }
 606
 607 static const struct file_operations wdt_fops = {
 608         .owner  = THIS_MODULE,
 609         .read   = wdt_read,
 610         .unlocked_ioctl = wdt_unlocked_ioctl,
 611         .write  = wdt_write,
 612         .open   = wdt_open,
 613         .release = wdt_release,
 614         .llseek = no_llseek,
 615 };
 616
 617 static struct miscdevice wdt_dev = {
 618         .minor = WATCHDOG_MINOR,
 619         .name = "watchdog",
 620         .fops = &wdt_fops,
 621 };
 622
 623 /*
 624  *      The WDT card needs to learn about soft shutdowns in order to
 625  *      turn the timebomb registers off.
 626  */
 627 static struct notifier_block wdt_notifier = {
 628         .notifier_call = wdt_notify_sys,
 629 };
 630 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
 631
 632 /*
 633  *****************************************************************************
 634  *
 635  *      Driver Interface
 636  *
 637  *****************************************************************************
 638  */
 639 static int m41t80_probe(struct i2c_client *client,
 640                         const struct i2c_device_id *id)
 641 {
 642         int rc = 0;
 643         struct rtc_device *rtc = NULL;
 644         struct rtc_time tm;
 645         struct m41t80_data *clientdata = NULL;
 646
 647         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
 648                                      | I2C_FUNC_SMBUS_BYTE_DATA))
 649                 return -ENODEV;
 650
 651         clientdata = devm_kzalloc(&client->dev, sizeof(*clientdata),
 652                                 GFP_KERNEL);
 653         if (!clientdata)
 654                 return -ENOMEM;
 655
 656         clientdata->features = id->driver_data;
 657         i2c_set_clientdata(client, clientdata);
 658
 659         rtc = devm_rtc_device_register(&client->dev, client->name,
 660                                         &m41t80_rtc_ops, THIS_MODULE);
 661         if (IS_ERR(rtc))
 662                 return PTR_ERR(rtc);
 663
 664         clientdata->rtc = rtc;
 665
 666         /* Make sure HT (Halt Update) bit is cleared */
 667         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 668
 669         if (rc >= 0 && rc & M41T80_ALHOUR_HT) {
 670                 if (clientdata->features & M41T80_FEATURE_HT) {
 671                         m41t80_get_datetime(client, &tm);
 672                         dev_info(&client->dev, "HT bit was set!\n");
 673                         dev_info(&client->dev,
 674                                  "Power Down at "
 675                                  "%04i-%02i-%02i %02i:%02i:%02i\n",
 676                                  tm.tm_year + 1900,
 677                                  tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
 678                                  tm.tm_min, tm.tm_sec);
 679                 }
 680                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_HOUR,
 681                                               rc & ~M41T80_ALHOUR_HT);
 682         }
 683
 684         if (rc < 0) {
 685                 dev_err(&client->dev, "Can't clear HT bit\n");
 686                 return rc;
 687         }
 688
 689         /* Make sure ST (stop) bit is cleared */
 690         rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 691
 692         if (rc >= 0 && rc & M41T80_SEC_ST)
 693                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 694                                               rc & ~M41T80_SEC_ST);
 695         if (rc < 0) {
 696                 dev_err(&client->dev, "Can't clear ST bit\n");
 697                 return rc;
 698         }
 699
 700         rc = m41t80_sysfs_register(&client->dev);
 701         if (rc)
 702                 return rc;
 703
 704 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 705         if (clientdata->features & M41T80_FEATURE_HT) {
 706                 save_client = client;
 707                 rc = misc_register(&wdt_dev);
 708                 if (rc)
 709                         return rc;
 710                 rc = register_reboot_notifier(&wdt_notifier);
 711                 if (rc) {
 712                         misc_deregister(&wdt_dev);
 713                         return rc;
 714                 }
 715         }
 716 #endif
 717         return 0;
 718 }
 719
 720 static int m41t80_remove(struct i2c_client *client)
 721 {
 722 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 723         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 724
 725         if (clientdata->features & M41T80_FEATURE_HT) {
 726                 misc_deregister(&wdt_dev);
 727                 unregister_reboot_notifier(&wdt_notifier);
 728         }
 729 #endif
 730
 731         return 0;
 732 }
 733
 734 static struct i2c_driver m41t80_driver = {
 735         .driver = {
 736                 .name = "rtc-m41t80",
 737         },
 738         .probe = m41t80_probe,
 739         .remove = m41t80_remove,
 740         .id_table = m41t80_id,
 741 };
 742
 743 module_i2c_driver(m41t80_driver);
 744
 745 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
 746 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
 747 MODULE_LICENSE("GPL");