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 #if defined(CONFIG_RTC_INTF_DEV) || defined(CONFIG_RTC_INTF_DEV_MODULE)
 217 static int
 218 m41t80_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 219 {
 220         struct i2c_client *client = to_i2c_client(dev);
 221         int rc;
 222
 223         switch (cmd) {
 224         case RTC_AIE_OFF:
 225         case RTC_AIE_ON:
 226                 break;
 227         default:
 228                 return -ENOIOCTLCMD;
 229         }
 230
 231         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 232         if (rc < 0)
 233                 goto err;
 234         switch (cmd) {
 235         case RTC_AIE_OFF:
 236                 rc &= ~M41T80_ALMON_AFE;
 237                 break;
 238         case RTC_AIE_ON:
 239                 rc |= M41T80_ALMON_AFE;
 240                 break;
 241         }
 242         if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, rc) < 0)
 243                 goto err;
 244         return 0;
 245 err:
 246         return -EIO;
 247 }
 248 #else
 249 #define m41t80_rtc_ioctl NULL
 250 #endif
 251
 252 static int m41t80_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 253 {
 254         struct i2c_client *client = to_i2c_client(dev);
 255         u8 wbuf[1 + M41T80_ALARM_REG_SIZE];
 256         u8 *buf = &wbuf[1];
 257         u8 *reg = buf - M41T80_REG_ALARM_MON;
 258         u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
 259         struct i2c_msg msgs_in[] = {
 260                 {
 261                         .addr   = client->addr,
 262                         .flags  = 0,
 263                         .len    = 1,
 264                         .buf    = dt_addr,
 265                 },
 266                 {
 267                         .addr   = client->addr,
 268                         .flags  = I2C_M_RD,
 269                         .len    = M41T80_ALARM_REG_SIZE,
 270                         .buf    = buf,
 271                 },
 272         };
 273         struct i2c_msg msgs[] = {
 274                 {
 275                         .addr   = client->addr,
 276                         .flags  = 0,
 277                         .len    = 1 + M41T80_ALARM_REG_SIZE,
 278                         .buf    = wbuf,
 279                  },
 280         };
 281
 282         if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
 283                 dev_err(&client->dev, "read error\n");
 284                 return -EIO;
 285         }
 286         reg[M41T80_REG_ALARM_MON] &= ~(0x1f | M41T80_ALMON_AFE);
 287         reg[M41T80_REG_ALARM_DAY] = 0;
 288         reg[M41T80_REG_ALARM_HOUR] &= ~(0x3f | 0x80);
 289         reg[M41T80_REG_ALARM_MIN] = 0;
 290         reg[M41T80_REG_ALARM_SEC] = 0;
 291
 292         wbuf[0] = M41T80_REG_ALARM_MON; /* offset into rtc's regs */
 293         reg[M41T80_REG_ALARM_SEC] |= t->time.tm_sec >= 0 ?
 294                 bin2bcd(t->time.tm_sec) : 0x80;
 295         reg[M41T80_REG_ALARM_MIN] |= t->time.tm_min >= 0 ?
 296                 bin2bcd(t->time.tm_min) : 0x80;
 297         reg[M41T80_REG_ALARM_HOUR] |= t->time.tm_hour >= 0 ?
 298                 bin2bcd(t->time.tm_hour) : 0x80;
 299         reg[M41T80_REG_ALARM_DAY] |= t->time.tm_mday >= 0 ?
 300                 bin2bcd(t->time.tm_mday) : 0x80;
 301         if (t->time.tm_mon >= 0)
 302                 reg[M41T80_REG_ALARM_MON] |= bin2bcd(t->time.tm_mon + 1);
 303         else
 304                 reg[M41T80_REG_ALARM_DAY] |= 0x40;
 305
 306         if (i2c_transfer(client->adapter, msgs, 1) != 1) {
 307                 dev_err(&client->dev, "write error\n");
 308                 return -EIO;
 309         }
 310
 311         if (t->enabled) {
 312                 reg[M41T80_REG_ALARM_MON] |= M41T80_ALMON_AFE;
 313                 if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 314                                               reg[M41T80_REG_ALARM_MON]) < 0) {
 315                         dev_err(&client->dev, "write error\n");
 316                         return -EIO;
 317                 }
 318         }
 319         return 0;
 320 }
 321
 322 static int m41t80_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 323 {
 324         struct i2c_client *client = to_i2c_client(dev);
 325         u8 buf[M41T80_ALARM_REG_SIZE + 1]; /* all alarm regs and flags */
 326         u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
 327         u8 *reg = buf - M41T80_REG_ALARM_MON;
 328         struct i2c_msg msgs[] = {
 329                 {
 330                         .addr   = client->addr,
 331                         .flags  = 0,
 332                         .len    = 1,
 333                         .buf    = dt_addr,
 334                 },
 335                 {
 336                         .addr   = client->addr,
 337                         .flags  = I2C_M_RD,
 338                         .len    = M41T80_ALARM_REG_SIZE + 1,
 339                         .buf    = buf,
 340                 },
 341         };
 342
 343         if (i2c_transfer(client->adapter, msgs, 2) < 0) {
 344                 dev_err(&client->dev, "read error\n");
 345                 return -EIO;
 346         }
 347         t->time.tm_sec = -1;
 348         t->time.tm_min = -1;
 349         t->time.tm_hour = -1;
 350         t->time.tm_mday = -1;
 351         t->time.tm_mon = -1;
 352         if (!(reg[M41T80_REG_ALARM_SEC] & 0x80))
 353                 t->time.tm_sec = bcd2bin(reg[M41T80_REG_ALARM_SEC] & 0x7f);
 354         if (!(reg[M41T80_REG_ALARM_MIN] & 0x80))
 355                 t->time.tm_min = bcd2bin(reg[M41T80_REG_ALARM_MIN] & 0x7f);
 356         if (!(reg[M41T80_REG_ALARM_HOUR] & 0x80))
 357                 t->time.tm_hour = bcd2bin(reg[M41T80_REG_ALARM_HOUR] & 0x3f);
 358         if (!(reg[M41T80_REG_ALARM_DAY] & 0x80))
 359                 t->time.tm_mday = bcd2bin(reg[M41T80_REG_ALARM_DAY] & 0x3f);
 360         if (!(reg[M41T80_REG_ALARM_DAY] & 0x40))
 361                 t->time.tm_mon = bcd2bin(reg[M41T80_REG_ALARM_MON] & 0x1f) - 1;
 362         t->time.tm_year = -1;
 363         t->time.tm_wday = -1;
 364         t->time.tm_yday = -1;
 365         t->time.tm_isdst = -1;
 366         t->enabled = !!(reg[M41T80_REG_ALARM_MON] & M41T80_ALMON_AFE);
 367         t->pending = !!(reg[M41T80_REG_FLAGS] & M41T80_FLAGS_AF);
 368         return 0;
 369 }
 370
 371 static struct rtc_class_ops m41t80_rtc_ops = {
 372         .read_time = m41t80_rtc_read_time,
 373         .set_time = m41t80_rtc_set_time,
 374         .read_alarm = m41t80_rtc_read_alarm,
 375         .set_alarm = m41t80_rtc_set_alarm,
 376         .proc = m41t80_rtc_proc,
 377         .ioctl = m41t80_rtc_ioctl,
 378 };
 379
 380 #if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
 381 static ssize_t m41t80_sysfs_show_flags(struct device *dev,
 382                                 struct device_attribute *attr, char *buf)
 383 {
 384         struct i2c_client *client = to_i2c_client(dev);
 385         int val;
 386
 387         val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 388         if (val < 0)
 389                 return -EIO;
 390         return sprintf(buf, "%#x\n", val);
 391 }
 392 static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
 393
 394 static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
 395                                 struct device_attribute *attr, char *buf)
 396 {
 397         struct i2c_client *client = to_i2c_client(dev);
 398         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 399         int val, reg_sqw;
 400
 401         if (!(clientdata->features & M41T80_FEATURE_SQ))
 402                 return -EINVAL;
 403
 404         reg_sqw = M41T80_REG_SQW;
 405         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 406                 reg_sqw = M41T80_REG_WDAY;
 407         val = i2c_smbus_read_byte_data(client, reg_sqw);
 408         if (val < 0)
 409                 return -EIO;
 410         val = (val >> 4) & 0xf;
 411         switch (val) {
 412         case 0:
 413                 break;
 414         case 1:
 415                 val = 32768;
 416                 break;
 417         default:
 418                 val = 32768 >> val;
 419         }
 420         return sprintf(buf, "%d\n", val);
 421 }
 422 static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
 423                                 struct device_attribute *attr,
 424                                 const char *buf, size_t count)
 425 {
 426         struct i2c_client *client = to_i2c_client(dev);
 427         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 428         int almon, sqw, reg_sqw;
 429         int val = simple_strtoul(buf, NULL, 0);
 430
 431         if (!(clientdata->features & M41T80_FEATURE_SQ))
 432                 return -EINVAL;
 433
 434         if (val) {
 435                 if (!is_power_of_2(val))
 436                         return -EINVAL;
 437                 val = ilog2(val);
 438                 if (val == 15)
 439                         val = 1;
 440                 else if (val < 14)
 441                         val = 15 - val;
 442                 else
 443                         return -EINVAL;
 444         }
 445         /* disable SQW, set SQW frequency & re-enable */
 446         almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 447         if (almon < 0)
 448                 return -EIO;
 449         reg_sqw = M41T80_REG_SQW;
 450         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 451                 reg_sqw = M41T80_REG_WDAY;
 452         sqw = i2c_smbus_read_byte_data(client, reg_sqw);
 453         if (sqw < 0)
 454                 return -EIO;
 455         sqw = (sqw & 0x0f) | (val << 4);
 456         if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 457                                       almon & ~M41T80_ALMON_SQWE) < 0 ||
 458             i2c_smbus_write_byte_data(client, reg_sqw, sqw) < 0)
 459                 return -EIO;
 460         if (val && i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 461                                              almon | M41T80_ALMON_SQWE) < 0)
 462                 return -EIO;
 463         return count;
 464 }
 465 static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
 466                    m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
 467
 468 static struct attribute *attrs[] = {
 469         &dev_attr_flags.attr,
 470         &dev_attr_sqwfreq.attr,
 471         NULL,
 472 };
 473 static struct attribute_group attr_group = {
 474         .attrs = attrs,
 475 };
 476
 477 static int m41t80_sysfs_register(struct device *dev)
 478 {
 479         return sysfs_create_group(&dev->kobj, &attr_group);
 480 }
 481 #else
 482 static int m41t80_sysfs_register(struct device *dev)
 483 {
 484         return 0;
 485 }
 486 #endif
 487
 488 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 489 /*
 490  *****************************************************************************
 491  *
 492  * Watchdog Driver
 493  *
 494  *****************************************************************************
 495  */
 496 static struct i2c_client *save_client;
 497
 498 /* Default margin */
 499 #define WD_TIMO 60              /* 1..31 seconds */
 500
 501 static int wdt_margin = WD_TIMO;
 502 module_param(wdt_margin, int, 0);
 503 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 504
 505 static unsigned long wdt_is_open;
 506 static int boot_flag;
 507
 508 /**
 509  *      wdt_ping:
 510  *
 511  *      Reload counter one with the watchdog timeout. We don't bother reloading
 512  *      the cascade counter.
 513  */
 514 static void wdt_ping(void)
 515 {
 516         unsigned char i2c_data[2];
 517         struct i2c_msg msgs1[1] = {
 518                 {
 519                         .addr   = save_client->addr,
 520                         .flags  = 0,
 521                         .len    = 2,
 522                         .buf    = i2c_data,
 523                 },
 524         };
 525         struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 526
 527         i2c_data[0] = 0x09;             /* watchdog register */
 528
 529         if (wdt_margin > 31)
 530                 i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 531         else
 532                 /*
 533                  * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 534                  */
 535                 i2c_data[1] = wdt_margin<<2 | 0x82;
 536
 537         /*
 538          * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 539          * that would be an invalid resolution.
 540          */
 541         if (clientdata->features & M41T80_FEATURE_WD)
 542                 i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 543
 544         i2c_transfer(save_client->adapter, msgs1, 1);
 545 }
 546
 547 /**
 548  *      wdt_disable:
 549  *
 550  *      disables watchdog.
 551  */
 552 static void wdt_disable(void)
 553 {
 554         unsigned char i2c_data[2], i2c_buf[0x10];
 555         struct i2c_msg msgs0[2] = {
 556                 {
 557                         .addr   = save_client->addr,
 558                         .flags  = 0,
 559                         .len    = 1,
 560                         .buf    = i2c_data,
 561                 },
 562                 {
 563                         .addr   = save_client->addr,
 564                         .flags  = I2C_M_RD,
 565                         .len    = 1,
 566                         .buf    = i2c_buf,
 567                 },
 568         };
 569         struct i2c_msg msgs1[1] = {
 570                 {
 571                         .addr   = save_client->addr,
 572                         .flags  = 0,
 573                         .len    = 2,
 574                         .buf    = i2c_data,
 575                 },
 576         };
 577
 578         i2c_data[0] = 0x09;
 579         i2c_transfer(save_client->adapter, msgs0, 2);
 580
 581         i2c_data[0] = 0x09;
 582         i2c_data[1] = 0x00;
 583         i2c_transfer(save_client->adapter, msgs1, 1);
 584 }
 585
 586 /**
 587  *      wdt_write:
 588  *      @file: file handle to the watchdog
 589  *      @buf: buffer to write (unused as data does not matter here
 590  *      @count: count of bytes
 591  *      @ppos: pointer to the position to write. No seeks allowed
 592  *
 593  *      A write to a watchdog device is defined as a keepalive signal. Any
 594  *      write of data will do, as we we don't define content meaning.
 595  */
 596 static ssize_t wdt_write(struct file *file, const char __user *buf,
 597                          size_t count, loff_t *ppos)
 598 {
 599         if (count) {
 600                 wdt_ping();
 601                 return 1;
 602         }
 603         return 0;
 604 }
 605
 606 static ssize_t wdt_read(struct file *file, char __user *buf,
 607                         size_t count, loff_t *ppos)
 608 {
 609         return 0;
 610 }
 611
 612 /**
 613  *      wdt_ioctl:
 614  *      @inode: inode of the device
 615  *      @file: file handle to the device
 616  *      @cmd: watchdog command
 617  *      @arg: argument pointer
 618  *
 619  *      The watchdog API defines a common set of functions for all watchdogs
 620  *      according to their available features. We only actually usefully support
 621  *      querying capabilities and current status.
 622  */
 623 static int wdt_ioctl(struct file *file, unsigned int cmd,
 624                      unsigned long arg)
 625 {
 626         int new_margin, rv;
 627         static struct watchdog_info ident = {
 628                 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 629                         WDIOF_SETTIMEOUT,
 630                 .firmware_version = 1,
 631                 .identity = "M41T80 WTD"
 632         };
 633
 634         switch (cmd) {
 635         case WDIOC_GETSUPPORT:
 636                 return copy_to_user((struct watchdog_info __user *)arg, &ident,
 637                                     sizeof(ident)) ? -EFAULT : 0;
 638
 639         case WDIOC_GETSTATUS:
 640         case WDIOC_GETBOOTSTATUS:
 641                 return put_user(boot_flag, (int __user *)arg);
 642         case WDIOC_KEEPALIVE:
 643                 wdt_ping();
 644                 return 0;
 645         case WDIOC_SETTIMEOUT:
 646                 if (get_user(new_margin, (int __user *)arg))
 647                         return -EFAULT;
 648                 /* Arbitrary, can't find the card's limits */
 649                 if (new_margin < 1 || new_margin > 124)
 650                         return -EINVAL;
 651                 wdt_margin = new_margin;
 652                 wdt_ping();
 653                 /* Fall */
 654         case WDIOC_GETTIMEOUT:
 655                 return put_user(wdt_margin, (int __user *)arg);
 656
 657         case WDIOC_SETOPTIONS:
 658                 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 659                         return -EFAULT;
 660
 661                 if (rv & WDIOS_DISABLECARD) {
 662                         pr_info("rtc-m41t80: disable watchdog\n");
 663                         wdt_disable();
 664                 }
 665
 666                 if (rv & WDIOS_ENABLECARD) {
 667                         pr_info("rtc-m41t80: enable watchdog\n");
 668                         wdt_ping();
 669                 }
 670
 671                 return -EINVAL;
 672         }
 673         return -ENOTTY;
 674 }
 675
 676 static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 677                                unsigned long arg)
 678 {
 679         int ret;
 680
 681         mutex_lock(&m41t80_rtc_mutex);
 682         ret = wdt_ioctl(file, cmd, arg);
 683         mutex_unlock(&m41t80_rtc_mutex);
 684
 685         return ret;
 686 }
 687
 688 /**
 689  *      wdt_open:
 690  *      @inode: inode of device
 691  *      @file: file handle to device
 692  *
 693  */
 694 static int wdt_open(struct inode *inode, struct file *file)
 695 {
 696         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 697                 mutex_lock(&m41t80_rtc_mutex);
 698                 if (test_and_set_bit(0, &wdt_is_open)) {
 699                         mutex_unlock(&m41t80_rtc_mutex);
 700                         return -EBUSY;
 701                 }
 702                 /*
 703                  *      Activate
 704                  */
 705                 wdt_is_open = 1;
 706                 mutex_unlock(&m41t80_rtc_mutex);
 707                 return nonseekable_open(inode, file);
 708         }
 709         return -ENODEV;
 710 }
 711
 712 /**
 713  *      wdt_close:
 714  *      @inode: inode to board
 715  *      @file: file handle to board
 716  *
 717  */
 718 static int wdt_release(struct inode *inode, struct file *file)
 719 {
 720         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 721                 clear_bit(0, &wdt_is_open);
 722         return 0;
 723 }
 724
 725 /**
 726  *      notify_sys:
 727  *      @this: our notifier block
 728  *      @code: the event being reported
 729  *      @unused: unused
 730  *
 731  *      Our notifier is called on system shutdowns. We want to turn the card
 732  *      off at reboot otherwise the machine will reboot again during memory
 733  *      test or worse yet during the following fsck. This would suck, in fact
 734  *      trust me - if it happens it does suck.
 735  */
 736 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 737                           void *unused)
 738 {
 739         if (code == SYS_DOWN || code == SYS_HALT)
 740                 /* Disable Watchdog */
 741                 wdt_disable();
 742         return NOTIFY_DONE;
 743 }
 744
 745 static const struct file_operations wdt_fops = {
 746         .owner  = THIS_MODULE,
 747         .read   = wdt_read,
 748         .unlocked_ioctl = wdt_unlocked_ioctl,
 749         .write  = wdt_write,
 750         .open   = wdt_open,
 751         .release = wdt_release,
 752         .llseek = no_llseek,
 753 };
 754
 755 static struct miscdevice wdt_dev = {
 756         .minor = WATCHDOG_MINOR,
 757         .name = "watchdog",
 758         .fops = &wdt_fops,
 759 };
 760
 761 /*
 762  *      The WDT card needs to learn about soft shutdowns in order to
 763  *      turn the timebomb registers off.
 764  */
 765 static struct notifier_block wdt_notifier = {
 766         .notifier_call = wdt_notify_sys,
 767 };
 768 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
 769
 770 /*
 771  *****************************************************************************
 772  *
 773  *      Driver Interface
 774  *
 775  *****************************************************************************
 776  */
 777 static int m41t80_probe(struct i2c_client *client,
 778                         const struct i2c_device_id *id)
 779 {
 780         int rc = 0;
 781         struct rtc_device *rtc = NULL;
 782         struct rtc_time tm;
 783         struct m41t80_data *clientdata = NULL;
 784
 785         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
 786                                      | I2C_FUNC_SMBUS_BYTE_DATA)) {
 787                 rc = -ENODEV;
 788                 goto exit;
 789         }
 790
 791         dev_info(&client->dev,
 792                  "chip found, driver version " DRV_VERSION "\n");
 793
 794         clientdata = kzalloc(sizeof(*clientdata), GFP_KERNEL);
 795         if (!clientdata) {
 796                 rc = -ENOMEM;
 797                 goto exit;
 798         }
 799
 800         rtc = rtc_device_register(client->name, &client->dev,
 801                                   &m41t80_rtc_ops, THIS_MODULE);
 802         if (IS_ERR(rtc)) {
 803                 rc = PTR_ERR(rtc);
 804                 rtc = NULL;
 805                 goto exit;
 806         }
 807
 808         clientdata->rtc = rtc;
 809         clientdata->features = id->driver_data;
 810         i2c_set_clientdata(client, clientdata);
 811
 812         /* Make sure HT (Halt Update) bit is cleared */
 813         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 814         if (rc < 0)
 815                 goto ht_err;
 816
 817         if (rc & M41T80_ALHOUR_HT) {
 818                 if (clientdata->features & M41T80_FEATURE_HT) {
 819                         m41t80_get_datetime(client, &tm);
 820                         dev_info(&client->dev, "HT bit was set!\n");
 821                         dev_info(&client->dev,
 822                                  "Power Down at "
 823                                  "%04i-%02i-%02i %02i:%02i:%02i\n",
 824                                  tm.tm_year + 1900,
 825                                  tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
 826                                  tm.tm_min, tm.tm_sec);
 827                 }
 828                 if (i2c_smbus_write_byte_data(client,
 829                                               M41T80_REG_ALARM_HOUR,
 830                                               rc & ~M41T80_ALHOUR_HT) < 0)
 831                         goto ht_err;
 832         }
 833
 834         /* Make sure ST (stop) bit is cleared */
 835         rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 836         if (rc < 0)
 837                 goto st_err;
 838
 839         if (rc & M41T80_SEC_ST) {
 840                 if (i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 841                                               rc & ~M41T80_SEC_ST) < 0)
 842                         goto st_err;
 843         }
 844
 845         rc = m41t80_sysfs_register(&client->dev);
 846         if (rc)
 847                 goto exit;
 848
 849 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 850         if (clientdata->features & M41T80_FEATURE_HT) {
 851                 save_client = client;
 852                 rc = misc_register(&wdt_dev);
 853                 if (rc)
 854                         goto exit;
 855                 rc = register_reboot_notifier(&wdt_notifier);
 856                 if (rc) {
 857                         misc_deregister(&wdt_dev);
 858                         goto exit;
 859                 }
 860         }
 861 #endif
 862         return 0;
 863
 864 st_err:
 865         rc = -EIO;
 866         dev_err(&client->dev, "Can't clear ST bit\n");
 867         goto exit;
 868 ht_err:
 869         rc = -EIO;
 870         dev_err(&client->dev, "Can't clear HT bit\n");
 871         goto exit;
 872
 873 exit:
 874         if (rtc)
 875                 rtc_device_unregister(rtc);
 876         kfree(clientdata);
 877         return rc;
 878 }
 879
 880 static int m41t80_remove(struct i2c_client *client)
 881 {
 882         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 883         struct rtc_device *rtc = clientdata->rtc;
 884
 885 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 886         if (clientdata->features & M41T80_FEATURE_HT) {
 887                 misc_deregister(&wdt_dev);
 888                 unregister_reboot_notifier(&wdt_notifier);
 889         }
 890 #endif
 891         if (rtc)
 892                 rtc_device_unregister(rtc);
 893         kfree(clientdata);
 894
 895         return 0;
 896 }
 897
 898 static struct i2c_driver m41t80_driver = {
 899         .driver = {
 900                 .name = "rtc-m41t80",
 901         },
 902         .probe = m41t80_probe,
 903         .remove = m41t80_remove,
 904         .id_table = m41t80_id,
 905 };
 906
 907 static int __init m41t80_rtc_init(void)
 908 {
 909         return i2c_add_driver(&m41t80_driver);
 910 }
 911
 912 static void __exit m41t80_rtc_exit(void)
 913 {
 914         i2c_del_driver(&m41t80_driver);
 915 }
 916
 917 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
 918 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
 919 MODULE_LICENSE("GPL");
 920 MODULE_VERSION(DRV_VERSION);
 921
 922 module_init(m41t80_rtc_init);
 923 module_exit(m41t80_rtc_exit);