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/smp_lock.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 const struct i2c_device_id m41t80_id[] = {
  72         { "m41t62", M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT },
  73         { "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
  74         { "m41t80", M41T80_FEATURE_SQ },
  75         { "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
  76         { "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  77         { "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  78         { "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  79         { "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  80         { "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  81         { "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  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 #if defined(CONFIG_RTC_INTF_DEV) || defined(CONFIG_RTC_INTF_DEV_MODULE)
 216 static int
 217 m41t80_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 218 {
 219         struct i2c_client *client = to_i2c_client(dev);
 220         int rc;
 221
 222         switch (cmd) {
 223         case RTC_AIE_OFF:
 224         case RTC_AIE_ON:
 225                 break;
 226         default:
 227                 return -ENOIOCTLCMD;
 228         }
 229
 230         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 231         if (rc < 0)
 232                 goto err;
 233         switch (cmd) {
 234         case RTC_AIE_OFF:
 235                 rc &= ~M41T80_ALMON_AFE;
 236                 break;
 237         case RTC_AIE_ON:
 238                 rc |= M41T80_ALMON_AFE;
 239                 break;
 240         }
 241         if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, rc) < 0)
 242                 goto err;
 243         return 0;
 244 err:
 245         return -EIO;
 246 }
 247 #else
 248 #define m41t80_rtc_ioctl NULL
 249 #endif
 250
 251 static int m41t80_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 252 {
 253         struct i2c_client *client = to_i2c_client(dev);
 254         u8 wbuf[1 + M41T80_ALARM_REG_SIZE];
 255         u8 *buf = &wbuf[1];
 256         u8 *reg = buf - M41T80_REG_ALARM_MON;
 257         u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
 258         struct i2c_msg msgs_in[] = {
 259                 {
 260                         .addr   = client->addr,
 261                         .flags  = 0,
 262                         .len    = 1,
 263                         .buf    = dt_addr,
 264                 },
 265                 {
 266                         .addr   = client->addr,
 267                         .flags  = I2C_M_RD,
 268                         .len    = M41T80_ALARM_REG_SIZE,
 269                         .buf    = buf,
 270                 },
 271         };
 272         struct i2c_msg msgs[] = {
 273                 {
 274                         .addr   = client->addr,
 275                         .flags  = 0,
 276                         .len    = 1 + M41T80_ALARM_REG_SIZE,
 277                         .buf    = wbuf,
 278                  },
 279         };
 280
 281         if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
 282                 dev_err(&client->dev, "read error\n");
 283                 return -EIO;
 284         }
 285         reg[M41T80_REG_ALARM_MON] &= ~(0x1f | M41T80_ALMON_AFE);
 286         reg[M41T80_REG_ALARM_DAY] = 0;
 287         reg[M41T80_REG_ALARM_HOUR] &= ~(0x3f | 0x80);
 288         reg[M41T80_REG_ALARM_MIN] = 0;
 289         reg[M41T80_REG_ALARM_SEC] = 0;
 290
 291         wbuf[0] = M41T80_REG_ALARM_MON; /* offset into rtc's regs */
 292         reg[M41T80_REG_ALARM_SEC] |= t->time.tm_sec >= 0 ?
 293                 bin2bcd(t->time.tm_sec) : 0x80;
 294         reg[M41T80_REG_ALARM_MIN] |= t->time.tm_min >= 0 ?
 295                 bin2bcd(t->time.tm_min) : 0x80;
 296         reg[M41T80_REG_ALARM_HOUR] |= t->time.tm_hour >= 0 ?
 297                 bin2bcd(t->time.tm_hour) : 0x80;
 298         reg[M41T80_REG_ALARM_DAY] |= t->time.tm_mday >= 0 ?
 299                 bin2bcd(t->time.tm_mday) : 0x80;
 300         if (t->time.tm_mon >= 0)
 301                 reg[M41T80_REG_ALARM_MON] |= bin2bcd(t->time.tm_mon + 1);
 302         else
 303                 reg[M41T80_REG_ALARM_DAY] |= 0x40;
 304
 305         if (i2c_transfer(client->adapter, msgs, 1) != 1) {
 306                 dev_err(&client->dev, "write error\n");
 307                 return -EIO;
 308         }
 309
 310         if (t->enabled) {
 311                 reg[M41T80_REG_ALARM_MON] |= M41T80_ALMON_AFE;
 312                 if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 313                                               reg[M41T80_REG_ALARM_MON]) < 0) {
 314                         dev_err(&client->dev, "write error\n");
 315                         return -EIO;
 316                 }
 317         }
 318         return 0;
 319 }
 320
 321 static int m41t80_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 322 {
 323         struct i2c_client *client = to_i2c_client(dev);
 324         u8 buf[M41T80_ALARM_REG_SIZE + 1]; /* all alarm regs and flags */
 325         u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
 326         u8 *reg = buf - M41T80_REG_ALARM_MON;
 327         struct i2c_msg msgs[] = {
 328                 {
 329                         .addr   = client->addr,
 330                         .flags  = 0,
 331                         .len    = 1,
 332                         .buf    = dt_addr,
 333                 },
 334                 {
 335                         .addr   = client->addr,
 336                         .flags  = I2C_M_RD,
 337                         .len    = M41T80_ALARM_REG_SIZE + 1,
 338                         .buf    = buf,
 339                 },
 340         };
 341
 342         if (i2c_transfer(client->adapter, msgs, 2) < 0) {
 343                 dev_err(&client->dev, "read error\n");
 344                 return -EIO;
 345         }
 346         t->time.tm_sec = -1;
 347         t->time.tm_min = -1;
 348         t->time.tm_hour = -1;
 349         t->time.tm_mday = -1;
 350         t->time.tm_mon = -1;
 351         if (!(reg[M41T80_REG_ALARM_SEC] & 0x80))
 352                 t->time.tm_sec = bcd2bin(reg[M41T80_REG_ALARM_SEC] & 0x7f);
 353         if (!(reg[M41T80_REG_ALARM_MIN] & 0x80))
 354                 t->time.tm_min = bcd2bin(reg[M41T80_REG_ALARM_MIN] & 0x7f);
 355         if (!(reg[M41T80_REG_ALARM_HOUR] & 0x80))
 356                 t->time.tm_hour = bcd2bin(reg[M41T80_REG_ALARM_HOUR] & 0x3f);
 357         if (!(reg[M41T80_REG_ALARM_DAY] & 0x80))
 358                 t->time.tm_mday = bcd2bin(reg[M41T80_REG_ALARM_DAY] & 0x3f);
 359         if (!(reg[M41T80_REG_ALARM_DAY] & 0x40))
 360                 t->time.tm_mon = bcd2bin(reg[M41T80_REG_ALARM_MON] & 0x1f) - 1;
 361         t->time.tm_year = -1;
 362         t->time.tm_wday = -1;
 363         t->time.tm_yday = -1;
 364         t->time.tm_isdst = -1;
 365         t->enabled = !!(reg[M41T80_REG_ALARM_MON] & M41T80_ALMON_AFE);
 366         t->pending = !!(reg[M41T80_REG_FLAGS] & M41T80_FLAGS_AF);
 367         return 0;
 368 }
 369
 370 static struct rtc_class_ops m41t80_rtc_ops = {
 371         .read_time = m41t80_rtc_read_time,
 372         .set_time = m41t80_rtc_set_time,
 373         .read_alarm = m41t80_rtc_read_alarm,
 374         .set_alarm = m41t80_rtc_set_alarm,
 375         .proc = m41t80_rtc_proc,
 376         .ioctl = m41t80_rtc_ioctl,
 377 };
 378
 379 #if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
 380 static ssize_t m41t80_sysfs_show_flags(struct device *dev,
 381                                 struct device_attribute *attr, char *buf)
 382 {
 383         struct i2c_client *client = to_i2c_client(dev);
 384         int val;
 385
 386         val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 387         if (val < 0)
 388                 return -EIO;
 389         return sprintf(buf, "%#x\n", val);
 390 }
 391 static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
 392
 393 static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
 394                                 struct device_attribute *attr, char *buf)
 395 {
 396         struct i2c_client *client = to_i2c_client(dev);
 397         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 398         int val, reg_sqw;
 399
 400         if (!(clientdata->features & M41T80_FEATURE_SQ))
 401                 return -EINVAL;
 402
 403         reg_sqw = M41T80_REG_SQW;
 404         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 405                 reg_sqw = M41T80_REG_WDAY;
 406         val = i2c_smbus_read_byte_data(client, reg_sqw);
 407         if (val < 0)
 408                 return -EIO;
 409         val = (val >> 4) & 0xf;
 410         switch (val) {
 411         case 0:
 412                 break;
 413         case 1:
 414                 val = 32768;
 415                 break;
 416         default:
 417                 val = 32768 >> val;
 418         }
 419         return sprintf(buf, "%d\n", val);
 420 }
 421 static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
 422                                 struct device_attribute *attr,
 423                                 const char *buf, size_t count)
 424 {
 425         struct i2c_client *client = to_i2c_client(dev);
 426         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 427         int almon, sqw, reg_sqw;
 428         int val = simple_strtoul(buf, NULL, 0);
 429
 430         if (!(clientdata->features & M41T80_FEATURE_SQ))
 431                 return -EINVAL;
 432
 433         if (val) {
 434                 if (!is_power_of_2(val))
 435                         return -EINVAL;
 436                 val = ilog2(val);
 437                 if (val == 15)
 438                         val = 1;
 439                 else if (val < 14)
 440                         val = 15 - val;
 441                 else
 442                         return -EINVAL;
 443         }
 444         /* disable SQW, set SQW frequency & re-enable */
 445         almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 446         if (almon < 0)
 447                 return -EIO;
 448         reg_sqw = M41T80_REG_SQW;
 449         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 450                 reg_sqw = M41T80_REG_WDAY;
 451         sqw = i2c_smbus_read_byte_data(client, reg_sqw);
 452         if (sqw < 0)
 453                 return -EIO;
 454         sqw = (sqw & 0x0f) | (val << 4);
 455         if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 456                                       almon & ~M41T80_ALMON_SQWE) < 0 ||
 457             i2c_smbus_write_byte_data(client, reg_sqw, sqw) < 0)
 458                 return -EIO;
 459         if (val && i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 460                                              almon | M41T80_ALMON_SQWE) < 0)
 461                 return -EIO;
 462         return count;
 463 }
 464 static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
 465                    m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
 466
 467 static struct attribute *attrs[] = {
 468         &dev_attr_flags.attr,
 469         &dev_attr_sqwfreq.attr,
 470         NULL,
 471 };
 472 static struct attribute_group attr_group = {
 473         .attrs = attrs,
 474 };
 475
 476 static int m41t80_sysfs_register(struct device *dev)
 477 {
 478         return sysfs_create_group(&dev->kobj, &attr_group);
 479 }
 480 #else
 481 static int m41t80_sysfs_register(struct device *dev)
 482 {
 483         return 0;
 484 }
 485 #endif
 486
 487 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 488 /*
 489  *****************************************************************************
 490  *
 491  * Watchdog Driver
 492  *
 493  *****************************************************************************
 494  */
 495 static struct i2c_client *save_client;
 496
 497 /* Default margin */
 498 #define WD_TIMO 60              /* 1..31 seconds */
 499
 500 static int wdt_margin = WD_TIMO;
 501 module_param(wdt_margin, int, 0);
 502 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 503
 504 static unsigned long wdt_is_open;
 505 static int boot_flag;
 506
 507 /**
 508  *      wdt_ping:
 509  *
 510  *      Reload counter one with the watchdog timeout. We don't bother reloading
 511  *      the cascade counter.
 512  */
 513 static void wdt_ping(void)
 514 {
 515         unsigned char i2c_data[2];
 516         struct i2c_msg msgs1[1] = {
 517                 {
 518                         .addr   = save_client->addr,
 519                         .flags  = 0,
 520                         .len    = 2,
 521                         .buf    = i2c_data,
 522                 },
 523         };
 524         struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 525
 526         i2c_data[0] = 0x09;             /* watchdog register */
 527
 528         if (wdt_margin > 31)
 529                 i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 530         else
 531                 /*
 532                  * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 533                  */
 534                 i2c_data[1] = wdt_margin<<2 | 0x82;
 535
 536         /*
 537          * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 538          * that would be an invalid resolution.
 539          */
 540         if (clientdata->features & M41T80_FEATURE_WD)
 541                 i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 542
 543         i2c_transfer(save_client->adapter, msgs1, 1);
 544 }
 545
 546 /**
 547  *      wdt_disable:
 548  *
 549  *      disables watchdog.
 550  */
 551 static void wdt_disable(void)
 552 {
 553         unsigned char i2c_data[2], i2c_buf[0x10];
 554         struct i2c_msg msgs0[2] = {
 555                 {
 556                         .addr   = save_client->addr,
 557                         .flags  = 0,
 558                         .len    = 1,
 559                         .buf    = i2c_data,
 560                 },
 561                 {
 562                         .addr   = save_client->addr,
 563                         .flags  = I2C_M_RD,
 564                         .len    = 1,
 565                         .buf    = i2c_buf,
 566                 },
 567         };
 568         struct i2c_msg msgs1[1] = {
 569                 {
 570                         .addr   = save_client->addr,
 571                         .flags  = 0,
 572                         .len    = 2,
 573                         .buf    = i2c_data,
 574                 },
 575         };
 576
 577         i2c_data[0] = 0x09;
 578         i2c_transfer(save_client->adapter, msgs0, 2);
 579
 580         i2c_data[0] = 0x09;
 581         i2c_data[1] = 0x00;
 582         i2c_transfer(save_client->adapter, msgs1, 1);
 583 }
 584
 585 /**
 586  *      wdt_write:
 587  *      @file: file handle to the watchdog
 588  *      @buf: buffer to write (unused as data does not matter here
 589  *      @count: count of bytes
 590  *      @ppos: pointer to the position to write. No seeks allowed
 591  *
 592  *      A write to a watchdog device is defined as a keepalive signal. Any
 593  *      write of data will do, as we we don't define content meaning.
 594  */
 595 static ssize_t wdt_write(struct file *file, const char __user *buf,
 596                          size_t count, loff_t *ppos)
 597 {
 598         if (count) {
 599                 wdt_ping();
 600                 return 1;
 601         }
 602         return 0;
 603 }
 604
 605 static ssize_t wdt_read(struct file *file, char __user *buf,
 606                         size_t count, loff_t *ppos)
 607 {
 608         return 0;
 609 }
 610
 611 /**
 612  *      wdt_ioctl:
 613  *      @inode: inode of the device
 614  *      @file: file handle to the device
 615  *      @cmd: watchdog command
 616  *      @arg: argument pointer
 617  *
 618  *      The watchdog API defines a common set of functions for all watchdogs
 619  *      according to their available features. We only actually usefully support
 620  *      querying capabilities and current status.
 621  */
 622 static int wdt_ioctl(struct file *file, unsigned int cmd,
 623                      unsigned long arg)
 624 {
 625         int new_margin, rv;
 626         static struct watchdog_info ident = {
 627                 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 628                         WDIOF_SETTIMEOUT,
 629                 .firmware_version = 1,
 630                 .identity = "M41T80 WTD"
 631         };
 632
 633         switch (cmd) {
 634         case WDIOC_GETSUPPORT:
 635                 return copy_to_user((struct watchdog_info __user *)arg, &ident,
 636                                     sizeof(ident)) ? -EFAULT : 0;
 637
 638         case WDIOC_GETSTATUS:
 639         case WDIOC_GETBOOTSTATUS:
 640                 return put_user(boot_flag, (int __user *)arg);
 641         case WDIOC_KEEPALIVE:
 642                 wdt_ping();
 643                 return 0;
 644         case WDIOC_SETTIMEOUT:
 645                 if (get_user(new_margin, (int __user *)arg))
 646                         return -EFAULT;
 647                 /* Arbitrary, can't find the card's limits */
 648                 if (new_margin < 1 || new_margin > 124)
 649                         return -EINVAL;
 650                 wdt_margin = new_margin;
 651                 wdt_ping();
 652                 /* Fall */
 653         case WDIOC_GETTIMEOUT:
 654                 return put_user(wdt_margin, (int __user *)arg);
 655
 656         case WDIOC_SETOPTIONS:
 657                 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 658                         return -EFAULT;
 659
 660                 if (rv & WDIOS_DISABLECARD) {
 661                         pr_info("rtc-m41t80: disable watchdog\n");
 662                         wdt_disable();
 663                 }
 664
 665                 if (rv & WDIOS_ENABLECARD) {
 666                         pr_info("rtc-m41t80: enable watchdog\n");
 667                         wdt_ping();
 668                 }
 669
 670                 return -EINVAL;
 671         }
 672         return -ENOTTY;
 673 }
 674
 675 static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 676                                unsigned long arg)
 677 {
 678         int ret;
 679
 680         lock_kernel();
 681         ret = wdt_ioctl(file, cmd, arg);
 682         unlock_kernel();
 683
 684         return ret;
 685 }
 686
 687 /**
 688  *      wdt_open:
 689  *      @inode: inode of device
 690  *      @file: file handle to device
 691  *
 692  */
 693 static int wdt_open(struct inode *inode, struct file *file)
 694 {
 695         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 696                 lock_kernel();
 697                 if (test_and_set_bit(0, &wdt_is_open)) {
 698                         unlock_kernel();
 699                         return -EBUSY;
 700                 }
 701                 /*
 702                  *      Activate
 703                  */
 704                 wdt_is_open = 1;
 705                 unlock_kernel();
 706                 return nonseekable_open(inode, file);
 707         }
 708         return -ENODEV;
 709 }
 710
 711 /**
 712  *      wdt_close:
 713  *      @inode: inode to board
 714  *      @file: file handle to board
 715  *
 716  */
 717 static int wdt_release(struct inode *inode, struct file *file)
 718 {
 719         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 720                 clear_bit(0, &wdt_is_open);
 721         return 0;
 722 }
 723
 724 /**
 725  *      notify_sys:
 726  *      @this: our notifier block
 727  *      @code: the event being reported
 728  *      @unused: unused
 729  *
 730  *      Our notifier is called on system shutdowns. We want to turn the card
 731  *      off at reboot otherwise the machine will reboot again during memory
 732  *      test or worse yet during the following fsck. This would suck, in fact
 733  *      trust me - if it happens it does suck.
 734  */
 735 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 736                           void *unused)
 737 {
 738         if (code == SYS_DOWN || code == SYS_HALT)
 739                 /* Disable Watchdog */
 740                 wdt_disable();
 741         return NOTIFY_DONE;
 742 }
 743
 744 static const struct file_operations wdt_fops = {
 745         .owner  = THIS_MODULE,
 746         .read   = wdt_read,
 747         .unlocked_ioctl = wdt_unlocked_ioctl,
 748         .write  = wdt_write,
 749         .open   = wdt_open,
 750         .release = wdt_release,
 751 };
 752
 753 static struct miscdevice wdt_dev = {
 754         .minor = WATCHDOG_MINOR,
 755         .name = "watchdog",
 756         .fops = &wdt_fops,
 757 };
 758
 759 /*
 760  *      The WDT card needs to learn about soft shutdowns in order to
 761  *      turn the timebomb registers off.
 762  */
 763 static struct notifier_block wdt_notifier = {
 764         .notifier_call = wdt_notify_sys,
 765 };
 766 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
 767
 768 /*
 769  *****************************************************************************
 770  *
 771  *      Driver Interface
 772  *
 773  *****************************************************************************
 774  */
 775 static int m41t80_probe(struct i2c_client *client,
 776                         const struct i2c_device_id *id)
 777 {
 778         int rc = 0;
 779         struct rtc_device *rtc = NULL;
 780         struct rtc_time tm;
 781         struct m41t80_data *clientdata = NULL;
 782
 783         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
 784                                      | I2C_FUNC_SMBUS_BYTE_DATA)) {
 785                 rc = -ENODEV;
 786                 goto exit;
 787         }
 788
 789         dev_info(&client->dev,
 790                  "chip found, driver version " DRV_VERSION "\n");
 791
 792         clientdata = kzalloc(sizeof(*clientdata), GFP_KERNEL);
 793         if (!clientdata) {
 794                 rc = -ENOMEM;
 795                 goto exit;
 796         }
 797
 798         rtc = rtc_device_register(client->name, &client->dev,
 799                                   &m41t80_rtc_ops, THIS_MODULE);
 800         if (IS_ERR(rtc)) {
 801                 rc = PTR_ERR(rtc);
 802                 rtc = NULL;
 803                 goto exit;
 804         }
 805
 806         clientdata->rtc = rtc;
 807         clientdata->features = id->driver_data;
 808         i2c_set_clientdata(client, clientdata);
 809
 810         /* Make sure HT (Halt Update) bit is cleared */
 811         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 812         if (rc < 0)
 813                 goto ht_err;
 814
 815         if (rc & M41T80_ALHOUR_HT) {
 816                 if (clientdata->features & M41T80_FEATURE_HT) {
 817                         m41t80_get_datetime(client, &tm);
 818                         dev_info(&client->dev, "HT bit was set!\n");
 819                         dev_info(&client->dev,
 820                                  "Power Down at "
 821                                  "%04i-%02i-%02i %02i:%02i:%02i\n",
 822                                  tm.tm_year + 1900,
 823                                  tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
 824                                  tm.tm_min, tm.tm_sec);
 825                 }
 826                 if (i2c_smbus_write_byte_data(client,
 827                                               M41T80_REG_ALARM_HOUR,
 828                                               rc & ~M41T80_ALHOUR_HT) < 0)
 829                         goto ht_err;
 830         }
 831
 832         /* Make sure ST (stop) bit is cleared */
 833         rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 834         if (rc < 0)
 835                 goto st_err;
 836
 837         if (rc & M41T80_SEC_ST) {
 838                 if (i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 839                                               rc & ~M41T80_SEC_ST) < 0)
 840                         goto st_err;
 841         }
 842
 843         rc = m41t80_sysfs_register(&client->dev);
 844         if (rc)
 845                 goto exit;
 846
 847 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 848         if (clientdata->features & M41T80_FEATURE_HT) {
 849                 save_client = client;
 850                 rc = misc_register(&wdt_dev);
 851                 if (rc)
 852                         goto exit;
 853                 rc = register_reboot_notifier(&wdt_notifier);
 854                 if (rc) {
 855                         misc_deregister(&wdt_dev);
 856                         goto exit;
 857                 }
 858         }
 859 #endif
 860         return 0;
 861
 862 st_err:
 863         rc = -EIO;
 864         dev_err(&client->dev, "Can't clear ST bit\n");
 865         goto exit;
 866 ht_err:
 867         rc = -EIO;
 868         dev_err(&client->dev, "Can't clear HT bit\n");
 869         goto exit;
 870
 871 exit:
 872         if (rtc)
 873                 rtc_device_unregister(rtc);
 874         kfree(clientdata);
 875         return rc;
 876 }
 877
 878 static int m41t80_remove(struct i2c_client *client)
 879 {
 880         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 881         struct rtc_device *rtc = clientdata->rtc;
 882
 883 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 884         if (clientdata->features & M41T80_FEATURE_HT) {
 885                 misc_deregister(&wdt_dev);
 886                 unregister_reboot_notifier(&wdt_notifier);
 887         }
 888 #endif
 889         if (rtc)
 890                 rtc_device_unregister(rtc);
 891         kfree(clientdata);
 892
 893         return 0;
 894 }
 895
 896 static struct i2c_driver m41t80_driver = {
 897         .driver = {
 898                 .name = "rtc-m41t80",
 899         },
 900         .probe = m41t80_probe,
 901         .remove = m41t80_remove,
 902         .id_table = m41t80_id,
 903 };
 904
 905 static int __init m41t80_rtc_init(void)
 906 {
 907         return i2c_add_driver(&m41t80_driver);
 908 }
 909
 910 static void __exit m41t80_rtc_exit(void)
 911 {
 912         i2c_del_driver(&m41t80_driver);
 913 }
 914
 915 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
 916 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
 917 MODULE_LICENSE("GPL");
 918 MODULE_VERSION(DRV_VERSION);
 919
 920 module_init(m41t80_rtc_init);
 921 module_exit(m41t80_rtc_exit);