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 static int m41t80_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 217 {
 218         struct i2c_client *client = to_i2c_client(dev);
 219         int rc;
 220
 221         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 222         if (rc < 0)
 223                 goto err;
 224
 225         if (enabled)
 226                 rc |= M41T80_ALMON_AFE;
 227         else
 228                 rc &= ~M41T80_ALMON_AFE;
 229
 230         if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, rc) < 0)
 231                 goto err;
 232
 233         return 0;
 234 err:
 235         return -EIO;
 236 }
 237
 238 static int m41t80_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 239 {
 240         struct i2c_client *client = to_i2c_client(dev);
 241         u8 wbuf[1 + M41T80_ALARM_REG_SIZE];
 242         u8 *buf = &wbuf[1];
 243         u8 *reg = buf - M41T80_REG_ALARM_MON;
 244         u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
 245         struct i2c_msg msgs_in[] = {
 246                 {
 247                         .addr   = client->addr,
 248                         .flags  = 0,
 249                         .len    = 1,
 250                         .buf    = dt_addr,
 251                 },
 252                 {
 253                         .addr   = client->addr,
 254                         .flags  = I2C_M_RD,
 255                         .len    = M41T80_ALARM_REG_SIZE,
 256                         .buf    = buf,
 257                 },
 258         };
 259         struct i2c_msg msgs[] = {
 260                 {
 261                         .addr   = client->addr,
 262                         .flags  = 0,
 263                         .len    = 1 + M41T80_ALARM_REG_SIZE,
 264                         .buf    = wbuf,
 265                  },
 266         };
 267
 268         if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
 269                 dev_err(&client->dev, "read error\n");
 270                 return -EIO;
 271         }
 272         reg[M41T80_REG_ALARM_MON] &= ~(0x1f | M41T80_ALMON_AFE);
 273         reg[M41T80_REG_ALARM_DAY] = 0;
 274         reg[M41T80_REG_ALARM_HOUR] &= ~(0x3f | 0x80);
 275         reg[M41T80_REG_ALARM_MIN] = 0;
 276         reg[M41T80_REG_ALARM_SEC] = 0;
 277
 278         wbuf[0] = M41T80_REG_ALARM_MON; /* offset into rtc's regs */
 279         reg[M41T80_REG_ALARM_SEC] |= t->time.tm_sec >= 0 ?
 280                 bin2bcd(t->time.tm_sec) : 0x80;
 281         reg[M41T80_REG_ALARM_MIN] |= t->time.tm_min >= 0 ?
 282                 bin2bcd(t->time.tm_min) : 0x80;
 283         reg[M41T80_REG_ALARM_HOUR] |= t->time.tm_hour >= 0 ?
 284                 bin2bcd(t->time.tm_hour) : 0x80;
 285         reg[M41T80_REG_ALARM_DAY] |= t->time.tm_mday >= 0 ?
 286                 bin2bcd(t->time.tm_mday) : 0x80;
 287         if (t->time.tm_mon >= 0)
 288                 reg[M41T80_REG_ALARM_MON] |= bin2bcd(t->time.tm_mon + 1);
 289         else
 290                 reg[M41T80_REG_ALARM_DAY] |= 0x40;
 291
 292         if (i2c_transfer(client->adapter, msgs, 1) != 1) {
 293                 dev_err(&client->dev, "write error\n");
 294                 return -EIO;
 295         }
 296
 297         if (t->enabled) {
 298                 reg[M41T80_REG_ALARM_MON] |= M41T80_ALMON_AFE;
 299                 if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 300                                               reg[M41T80_REG_ALARM_MON]) < 0) {
 301                         dev_err(&client->dev, "write error\n");
 302                         return -EIO;
 303                 }
 304         }
 305         return 0;
 306 }
 307
 308 static int m41t80_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 309 {
 310         struct i2c_client *client = to_i2c_client(dev);
 311         u8 buf[M41T80_ALARM_REG_SIZE + 1]; /* all alarm regs and flags */
 312         u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
 313         u8 *reg = buf - M41T80_REG_ALARM_MON;
 314         struct i2c_msg msgs[] = {
 315                 {
 316                         .addr   = client->addr,
 317                         .flags  = 0,
 318                         .len    = 1,
 319                         .buf    = dt_addr,
 320                 },
 321                 {
 322                         .addr   = client->addr,
 323                         .flags  = I2C_M_RD,
 324                         .len    = M41T80_ALARM_REG_SIZE + 1,
 325                         .buf    = buf,
 326                 },
 327         };
 328
 329         if (i2c_transfer(client->adapter, msgs, 2) < 0) {
 330                 dev_err(&client->dev, "read error\n");
 331                 return -EIO;
 332         }
 333         t->time.tm_sec = -1;
 334         t->time.tm_min = -1;
 335         t->time.tm_hour = -1;
 336         t->time.tm_mday = -1;
 337         t->time.tm_mon = -1;
 338         if (!(reg[M41T80_REG_ALARM_SEC] & 0x80))
 339                 t->time.tm_sec = bcd2bin(reg[M41T80_REG_ALARM_SEC] & 0x7f);
 340         if (!(reg[M41T80_REG_ALARM_MIN] & 0x80))
 341                 t->time.tm_min = bcd2bin(reg[M41T80_REG_ALARM_MIN] & 0x7f);
 342         if (!(reg[M41T80_REG_ALARM_HOUR] & 0x80))
 343                 t->time.tm_hour = bcd2bin(reg[M41T80_REG_ALARM_HOUR] & 0x3f);
 344         if (!(reg[M41T80_REG_ALARM_DAY] & 0x80))
 345                 t->time.tm_mday = bcd2bin(reg[M41T80_REG_ALARM_DAY] & 0x3f);
 346         if (!(reg[M41T80_REG_ALARM_DAY] & 0x40))
 347                 t->time.tm_mon = bcd2bin(reg[M41T80_REG_ALARM_MON] & 0x1f) - 1;
 348         t->time.tm_year = -1;
 349         t->time.tm_wday = -1;
 350         t->time.tm_yday = -1;
 351         t->time.tm_isdst = -1;
 352         t->enabled = !!(reg[M41T80_REG_ALARM_MON] & M41T80_ALMON_AFE);
 353         t->pending = !!(reg[M41T80_REG_FLAGS] & M41T80_FLAGS_AF);
 354         return 0;
 355 }
 356
 357 static struct rtc_class_ops m41t80_rtc_ops = {
 358         .read_time = m41t80_rtc_read_time,
 359         .set_time = m41t80_rtc_set_time,
 360         .read_alarm = m41t80_rtc_read_alarm,
 361         .set_alarm = m41t80_rtc_set_alarm,
 362         .proc = m41t80_rtc_proc,
 363         .alarm_irq_enable = m41t80_rtc_alarm_irq_enable,
 364 };
 365
 366 #if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
 367 static ssize_t m41t80_sysfs_show_flags(struct device *dev,
 368                                 struct device_attribute *attr, char *buf)
 369 {
 370         struct i2c_client *client = to_i2c_client(dev);
 371         int val;
 372
 373         val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 374         if (val < 0)
 375                 return -EIO;
 376         return sprintf(buf, "%#x\n", val);
 377 }
 378 static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
 379
 380 static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
 381                                 struct device_attribute *attr, char *buf)
 382 {
 383         struct i2c_client *client = to_i2c_client(dev);
 384         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 385         int val, reg_sqw;
 386
 387         if (!(clientdata->features & M41T80_FEATURE_SQ))
 388                 return -EINVAL;
 389
 390         reg_sqw = M41T80_REG_SQW;
 391         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 392                 reg_sqw = M41T80_REG_WDAY;
 393         val = i2c_smbus_read_byte_data(client, reg_sqw);
 394         if (val < 0)
 395                 return -EIO;
 396         val = (val >> 4) & 0xf;
 397         switch (val) {
 398         case 0:
 399                 break;
 400         case 1:
 401                 val = 32768;
 402                 break;
 403         default:
 404                 val = 32768 >> val;
 405         }
 406         return sprintf(buf, "%d\n", val);
 407 }
 408 static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
 409                                 struct device_attribute *attr,
 410                                 const char *buf, size_t count)
 411 {
 412         struct i2c_client *client = to_i2c_client(dev);
 413         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 414         int almon, sqw, reg_sqw;
 415         int val = simple_strtoul(buf, NULL, 0);
 416
 417         if (!(clientdata->features & M41T80_FEATURE_SQ))
 418                 return -EINVAL;
 419
 420         if (val) {
 421                 if (!is_power_of_2(val))
 422                         return -EINVAL;
 423                 val = ilog2(val);
 424                 if (val == 15)
 425                         val = 1;
 426                 else if (val < 14)
 427                         val = 15 - val;
 428                 else
 429                         return -EINVAL;
 430         }
 431         /* disable SQW, set SQW frequency & re-enable */
 432         almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 433         if (almon < 0)
 434                 return -EIO;
 435         reg_sqw = M41T80_REG_SQW;
 436         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 437                 reg_sqw = M41T80_REG_WDAY;
 438         sqw = i2c_smbus_read_byte_data(client, reg_sqw);
 439         if (sqw < 0)
 440                 return -EIO;
 441         sqw = (sqw & 0x0f) | (val << 4);
 442         if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 443                                       almon & ~M41T80_ALMON_SQWE) < 0 ||
 444             i2c_smbus_write_byte_data(client, reg_sqw, sqw) < 0)
 445                 return -EIO;
 446         if (val && i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 447                                              almon | M41T80_ALMON_SQWE) < 0)
 448                 return -EIO;
 449         return count;
 450 }
 451 static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
 452                    m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
 453
 454 static struct attribute *attrs[] = {
 455         &dev_attr_flags.attr,
 456         &dev_attr_sqwfreq.attr,
 457         NULL,
 458 };
 459 static struct attribute_group attr_group = {
 460         .attrs = attrs,
 461 };
 462
 463 static int m41t80_sysfs_register(struct device *dev)
 464 {
 465         return sysfs_create_group(&dev->kobj, &attr_group);
 466 }
 467 #else
 468 static int m41t80_sysfs_register(struct device *dev)
 469 {
 470         return 0;
 471 }
 472 #endif
 473
 474 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 475 /*
 476  *****************************************************************************
 477  *
 478  * Watchdog Driver
 479  *
 480  *****************************************************************************
 481  */
 482 static struct i2c_client *save_client;
 483
 484 /* Default margin */
 485 #define WD_TIMO 60              /* 1..31 seconds */
 486
 487 static int wdt_margin = WD_TIMO;
 488 module_param(wdt_margin, int, 0);
 489 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 490
 491 static unsigned long wdt_is_open;
 492 static int boot_flag;
 493
 494 /**
 495  *      wdt_ping:
 496  *
 497  *      Reload counter one with the watchdog timeout. We don't bother reloading
 498  *      the cascade counter.
 499  */
 500 static void wdt_ping(void)
 501 {
 502         unsigned char i2c_data[2];
 503         struct i2c_msg msgs1[1] = {
 504                 {
 505                         .addr   = save_client->addr,
 506                         .flags  = 0,
 507                         .len    = 2,
 508                         .buf    = i2c_data,
 509                 },
 510         };
 511         struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 512
 513         i2c_data[0] = 0x09;             /* watchdog register */
 514
 515         if (wdt_margin > 31)
 516                 i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 517         else
 518                 /*
 519                  * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 520                  */
 521                 i2c_data[1] = wdt_margin<<2 | 0x82;
 522
 523         /*
 524          * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 525          * that would be an invalid resolution.
 526          */
 527         if (clientdata->features & M41T80_FEATURE_WD)
 528                 i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 529
 530         i2c_transfer(save_client->adapter, msgs1, 1);
 531 }
 532
 533 /**
 534  *      wdt_disable:
 535  *
 536  *      disables watchdog.
 537  */
 538 static void wdt_disable(void)
 539 {
 540         unsigned char i2c_data[2], i2c_buf[0x10];
 541         struct i2c_msg msgs0[2] = {
 542                 {
 543                         .addr   = save_client->addr,
 544                         .flags  = 0,
 545                         .len    = 1,
 546                         .buf    = i2c_data,
 547                 },
 548                 {
 549                         .addr   = save_client->addr,
 550                         .flags  = I2C_M_RD,
 551                         .len    = 1,
 552                         .buf    = i2c_buf,
 553                 },
 554         };
 555         struct i2c_msg msgs1[1] = {
 556                 {
 557                         .addr   = save_client->addr,
 558                         .flags  = 0,
 559                         .len    = 2,
 560                         .buf    = i2c_data,
 561                 },
 562         };
 563
 564         i2c_data[0] = 0x09;
 565         i2c_transfer(save_client->adapter, msgs0, 2);
 566
 567         i2c_data[0] = 0x09;
 568         i2c_data[1] = 0x00;
 569         i2c_transfer(save_client->adapter, msgs1, 1);
 570 }
 571
 572 /**
 573  *      wdt_write:
 574  *      @file: file handle to the watchdog
 575  *      @buf: buffer to write (unused as data does not matter here
 576  *      @count: count of bytes
 577  *      @ppos: pointer to the position to write. No seeks allowed
 578  *
 579  *      A write to a watchdog device is defined as a keepalive signal. Any
 580  *      write of data will do, as we we don't define content meaning.
 581  */
 582 static ssize_t wdt_write(struct file *file, const char __user *buf,
 583                          size_t count, loff_t *ppos)
 584 {
 585         if (count) {
 586                 wdt_ping();
 587                 return 1;
 588         }
 589         return 0;
 590 }
 591
 592 static ssize_t wdt_read(struct file *file, char __user *buf,
 593                         size_t count, loff_t *ppos)
 594 {
 595         return 0;
 596 }
 597
 598 /**
 599  *      wdt_ioctl:
 600  *      @inode: inode of the device
 601  *      @file: file handle to the device
 602  *      @cmd: watchdog command
 603  *      @arg: argument pointer
 604  *
 605  *      The watchdog API defines a common set of functions for all watchdogs
 606  *      according to their available features. We only actually usefully support
 607  *      querying capabilities and current status.
 608  */
 609 static int wdt_ioctl(struct file *file, unsigned int cmd,
 610                      unsigned long arg)
 611 {
 612         int new_margin, rv;
 613         static struct watchdog_info ident = {
 614                 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 615                         WDIOF_SETTIMEOUT,
 616                 .firmware_version = 1,
 617                 .identity = "M41T80 WTD"
 618         };
 619
 620         switch (cmd) {
 621         case WDIOC_GETSUPPORT:
 622                 return copy_to_user((struct watchdog_info __user *)arg, &ident,
 623                                     sizeof(ident)) ? -EFAULT : 0;
 624
 625         case WDIOC_GETSTATUS:
 626         case WDIOC_GETBOOTSTATUS:
 627                 return put_user(boot_flag, (int __user *)arg);
 628         case WDIOC_KEEPALIVE:
 629                 wdt_ping();
 630                 return 0;
 631         case WDIOC_SETTIMEOUT:
 632                 if (get_user(new_margin, (int __user *)arg))
 633                         return -EFAULT;
 634                 /* Arbitrary, can't find the card's limits */
 635                 if (new_margin < 1 || new_margin > 124)
 636                         return -EINVAL;
 637                 wdt_margin = new_margin;
 638                 wdt_ping();
 639                 /* Fall */
 640         case WDIOC_GETTIMEOUT:
 641                 return put_user(wdt_margin, (int __user *)arg);
 642
 643         case WDIOC_SETOPTIONS:
 644                 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 645                         return -EFAULT;
 646
 647                 if (rv & WDIOS_DISABLECARD) {
 648                         pr_info("rtc-m41t80: disable watchdog\n");
 649                         wdt_disable();
 650                 }
 651
 652                 if (rv & WDIOS_ENABLECARD) {
 653                         pr_info("rtc-m41t80: enable watchdog\n");
 654                         wdt_ping();
 655                 }
 656
 657                 return -EINVAL;
 658         }
 659         return -ENOTTY;
 660 }
 661
 662 static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 663                                unsigned long arg)
 664 {
 665         int ret;
 666
 667         mutex_lock(&m41t80_rtc_mutex);
 668         ret = wdt_ioctl(file, cmd, arg);
 669         mutex_unlock(&m41t80_rtc_mutex);
 670
 671         return ret;
 672 }
 673
 674 /**
 675  *      wdt_open:
 676  *      @inode: inode of device
 677  *      @file: file handle to device
 678  *
 679  */
 680 static int wdt_open(struct inode *inode, struct file *file)
 681 {
 682         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 683                 mutex_lock(&m41t80_rtc_mutex);
 684                 if (test_and_set_bit(0, &wdt_is_open)) {
 685                         mutex_unlock(&m41t80_rtc_mutex);
 686                         return -EBUSY;
 687                 }
 688                 /*
 689                  *      Activate
 690                  */
 691                 wdt_is_open = 1;
 692                 mutex_unlock(&m41t80_rtc_mutex);
 693                 return nonseekable_open(inode, file);
 694         }
 695         return -ENODEV;
 696 }
 697
 698 /**
 699  *      wdt_close:
 700  *      @inode: inode to board
 701  *      @file: file handle to board
 702  *
 703  */
 704 static int wdt_release(struct inode *inode, struct file *file)
 705 {
 706         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 707                 clear_bit(0, &wdt_is_open);
 708         return 0;
 709 }
 710
 711 /**
 712  *      notify_sys:
 713  *      @this: our notifier block
 714  *      @code: the event being reported
 715  *      @unused: unused
 716  *
 717  *      Our notifier is called on system shutdowns. We want to turn the card
 718  *      off at reboot otherwise the machine will reboot again during memory
 719  *      test or worse yet during the following fsck. This would suck, in fact
 720  *      trust me - if it happens it does suck.
 721  */
 722 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 723                           void *unused)
 724 {
 725         if (code == SYS_DOWN || code == SYS_HALT)
 726                 /* Disable Watchdog */
 727                 wdt_disable();
 728         return NOTIFY_DONE;
 729 }
 730
 731 static const struct file_operations wdt_fops = {
 732         .owner  = THIS_MODULE,
 733         .read   = wdt_read,
 734         .unlocked_ioctl = wdt_unlocked_ioctl,
 735         .write  = wdt_write,
 736         .open   = wdt_open,
 737         .release = wdt_release,
 738         .llseek = no_llseek,
 739 };
 740
 741 static struct miscdevice wdt_dev = {
 742         .minor = WATCHDOG_MINOR,
 743         .name = "watchdog",
 744         .fops = &wdt_fops,
 745 };
 746
 747 /*
 748  *      The WDT card needs to learn about soft shutdowns in order to
 749  *      turn the timebomb registers off.
 750  */
 751 static struct notifier_block wdt_notifier = {
 752         .notifier_call = wdt_notify_sys,
 753 };
 754 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
 755
 756 /*
 757  *****************************************************************************
 758  *
 759  *      Driver Interface
 760  *
 761  *****************************************************************************
 762  */
 763 static int m41t80_probe(struct i2c_client *client,
 764                         const struct i2c_device_id *id)
 765 {
 766         int rc = 0;
 767         struct rtc_device *rtc = NULL;
 768         struct rtc_time tm;
 769         struct m41t80_data *clientdata = NULL;
 770
 771         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
 772                                      | I2C_FUNC_SMBUS_BYTE_DATA)) {
 773                 rc = -ENODEV;
 774                 goto exit;
 775         }
 776
 777         dev_info(&client->dev,
 778                  "chip found, driver version " DRV_VERSION "\n");
 779
 780         clientdata = kzalloc(sizeof(*clientdata), GFP_KERNEL);
 781         if (!clientdata) {
 782                 rc = -ENOMEM;
 783                 goto exit;
 784         }
 785
 786         rtc = rtc_device_register(client->name, &client->dev,
 787                                   &m41t80_rtc_ops, THIS_MODULE);
 788         if (IS_ERR(rtc)) {
 789                 rc = PTR_ERR(rtc);
 790                 rtc = NULL;
 791                 goto exit;
 792         }
 793
 794         clientdata->rtc = rtc;
 795         clientdata->features = id->driver_data;
 796         i2c_set_clientdata(client, clientdata);
 797
 798         /* Make sure HT (Halt Update) bit is cleared */
 799         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 800         if (rc < 0)
 801                 goto ht_err;
 802
 803         if (rc & M41T80_ALHOUR_HT) {
 804                 if (clientdata->features & M41T80_FEATURE_HT) {
 805                         m41t80_get_datetime(client, &tm);
 806                         dev_info(&client->dev, "HT bit was set!\n");
 807                         dev_info(&client->dev,
 808                                  "Power Down at "
 809                                  "%04i-%02i-%02i %02i:%02i:%02i\n",
 810                                  tm.tm_year + 1900,
 811                                  tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
 812                                  tm.tm_min, tm.tm_sec);
 813                 }
 814                 if (i2c_smbus_write_byte_data(client,
 815                                               M41T80_REG_ALARM_HOUR,
 816                                               rc & ~M41T80_ALHOUR_HT) < 0)
 817                         goto ht_err;
 818         }
 819
 820         /* Make sure ST (stop) bit is cleared */
 821         rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 822         if (rc < 0)
 823                 goto st_err;
 824
 825         if (rc & M41T80_SEC_ST) {
 826                 if (i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 827                                               rc & ~M41T80_SEC_ST) < 0)
 828                         goto st_err;
 829         }
 830
 831         rc = m41t80_sysfs_register(&client->dev);
 832         if (rc)
 833                 goto exit;
 834
 835 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 836         if (clientdata->features & M41T80_FEATURE_HT) {
 837                 save_client = client;
 838                 rc = misc_register(&wdt_dev);
 839                 if (rc)
 840                         goto exit;
 841                 rc = register_reboot_notifier(&wdt_notifier);
 842                 if (rc) {
 843                         misc_deregister(&wdt_dev);
 844                         goto exit;
 845                 }
 846         }
 847 #endif
 848         return 0;
 849
 850 st_err:
 851         rc = -EIO;
 852         dev_err(&client->dev, "Can't clear ST bit\n");
 853         goto exit;
 854 ht_err:
 855         rc = -EIO;
 856         dev_err(&client->dev, "Can't clear HT bit\n");
 857         goto exit;
 858
 859 exit:
 860         if (rtc)
 861                 rtc_device_unregister(rtc);
 862         kfree(clientdata);
 863         return rc;
 864 }
 865
 866 static int m41t80_remove(struct i2c_client *client)
 867 {
 868         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 869         struct rtc_device *rtc = clientdata->rtc;
 870
 871 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 872         if (clientdata->features & M41T80_FEATURE_HT) {
 873                 misc_deregister(&wdt_dev);
 874                 unregister_reboot_notifier(&wdt_notifier);
 875         }
 876 #endif
 877         if (rtc)
 878                 rtc_device_unregister(rtc);
 879         kfree(clientdata);
 880
 881         return 0;
 882 }
 883
 884 static struct i2c_driver m41t80_driver = {
 885         .driver = {
 886                 .name = "rtc-m41t80",
 887         },
 888         .probe = m41t80_probe,
 889         .remove = m41t80_remove,
 890         .id_table = m41t80_id,
 891 };
 892
 893 static int __init m41t80_rtc_init(void)
 894 {
 895         return i2c_add_driver(&m41t80_driver);
 896 }
 897
 898 static void __exit m41t80_rtc_exit(void)
 899 {
 900         i2c_del_driver(&m41t80_driver);
 901 }
 902
 903 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
 904 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
 905 MODULE_LICENSE("GPL");
 906 MODULE_VERSION(DRV_VERSION);
 907
 908 module_init(m41t80_rtc_init);
 909 module_exit(m41t80_rtc_exit);