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         /*
 361          * XXX - m41t80 alarm functionality is reported broken.
 362          * until it is fixed, don't register alarm functions.
 363          *
 364         .read_alarm = m41t80_rtc_read_alarm,
 365         .set_alarm = m41t80_rtc_set_alarm,
 366         */
 367         .proc = m41t80_rtc_proc,
 368         /*
 369          * See above comment on broken alarm
 370          *
 371         .alarm_irq_enable = m41t80_rtc_alarm_irq_enable,
 372         */
 373 };
 374
 375 #if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
 376 static ssize_t m41t80_sysfs_show_flags(struct device *dev,
 377                                 struct device_attribute *attr, char *buf)
 378 {
 379         struct i2c_client *client = to_i2c_client(dev);
 380         int val;
 381
 382         val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 383         if (val < 0)
 384                 return -EIO;
 385         return sprintf(buf, "%#x\n", val);
 386 }
 387 static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
 388
 389 static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
 390                                 struct device_attribute *attr, char *buf)
 391 {
 392         struct i2c_client *client = to_i2c_client(dev);
 393         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 394         int val, reg_sqw;
 395
 396         if (!(clientdata->features & M41T80_FEATURE_SQ))
 397                 return -EINVAL;
 398
 399         reg_sqw = M41T80_REG_SQW;
 400         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 401                 reg_sqw = M41T80_REG_WDAY;
 402         val = i2c_smbus_read_byte_data(client, reg_sqw);
 403         if (val < 0)
 404                 return -EIO;
 405         val = (val >> 4) & 0xf;
 406         switch (val) {
 407         case 0:
 408                 break;
 409         case 1:
 410                 val = 32768;
 411                 break;
 412         default:
 413                 val = 32768 >> val;
 414         }
 415         return sprintf(buf, "%d\n", val);
 416 }
 417 static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
 418                                 struct device_attribute *attr,
 419                                 const char *buf, size_t count)
 420 {
 421         struct i2c_client *client = to_i2c_client(dev);
 422         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 423         int almon, sqw, reg_sqw;
 424         int val = simple_strtoul(buf, NULL, 0);
 425
 426         if (!(clientdata->features & M41T80_FEATURE_SQ))
 427                 return -EINVAL;
 428
 429         if (val) {
 430                 if (!is_power_of_2(val))
 431                         return -EINVAL;
 432                 val = ilog2(val);
 433                 if (val == 15)
 434                         val = 1;
 435                 else if (val < 14)
 436                         val = 15 - val;
 437                 else
 438                         return -EINVAL;
 439         }
 440         /* disable SQW, set SQW frequency & re-enable */
 441         almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 442         if (almon < 0)
 443                 return -EIO;
 444         reg_sqw = M41T80_REG_SQW;
 445         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 446                 reg_sqw = M41T80_REG_WDAY;
 447         sqw = i2c_smbus_read_byte_data(client, reg_sqw);
 448         if (sqw < 0)
 449                 return -EIO;
 450         sqw = (sqw & 0x0f) | (val << 4);
 451         if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 452                                       almon & ~M41T80_ALMON_SQWE) < 0 ||
 453             i2c_smbus_write_byte_data(client, reg_sqw, sqw) < 0)
 454                 return -EIO;
 455         if (val && i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 456                                              almon | M41T80_ALMON_SQWE) < 0)
 457                 return -EIO;
 458         return count;
 459 }
 460 static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
 461                    m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
 462
 463 static struct attribute *attrs[] = {
 464         &dev_attr_flags.attr,
 465         &dev_attr_sqwfreq.attr,
 466         NULL,
 467 };
 468 static struct attribute_group attr_group = {
 469         .attrs = attrs,
 470 };
 471
 472 static int m41t80_sysfs_register(struct device *dev)
 473 {
 474         return sysfs_create_group(&dev->kobj, &attr_group);
 475 }
 476 #else
 477 static int m41t80_sysfs_register(struct device *dev)
 478 {
 479         return 0;
 480 }
 481 #endif
 482
 483 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 484 /*
 485  *****************************************************************************
 486  *
 487  * Watchdog Driver
 488  *
 489  *****************************************************************************
 490  */
 491 static struct i2c_client *save_client;
 492
 493 /* Default margin */
 494 #define WD_TIMO 60              /* 1..31 seconds */
 495
 496 static int wdt_margin = WD_TIMO;
 497 module_param(wdt_margin, int, 0);
 498 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 499
 500 static unsigned long wdt_is_open;
 501 static int boot_flag;
 502
 503 /**
 504  *      wdt_ping:
 505  *
 506  *      Reload counter one with the watchdog timeout. We don't bother reloading
 507  *      the cascade counter.
 508  */
 509 static void wdt_ping(void)
 510 {
 511         unsigned char i2c_data[2];
 512         struct i2c_msg msgs1[1] = {
 513                 {
 514                         .addr   = save_client->addr,
 515                         .flags  = 0,
 516                         .len    = 2,
 517                         .buf    = i2c_data,
 518                 },
 519         };
 520         struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 521
 522         i2c_data[0] = 0x09;             /* watchdog register */
 523
 524         if (wdt_margin > 31)
 525                 i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 526         else
 527                 /*
 528                  * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 529                  */
 530                 i2c_data[1] = wdt_margin<<2 | 0x82;
 531
 532         /*
 533          * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 534          * that would be an invalid resolution.
 535          */
 536         if (clientdata->features & M41T80_FEATURE_WD)
 537                 i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 538
 539         i2c_transfer(save_client->adapter, msgs1, 1);
 540 }
 541
 542 /**
 543  *      wdt_disable:
 544  *
 545  *      disables watchdog.
 546  */
 547 static void wdt_disable(void)
 548 {
 549         unsigned char i2c_data[2], i2c_buf[0x10];
 550         struct i2c_msg msgs0[2] = {
 551                 {
 552                         .addr   = save_client->addr,
 553                         .flags  = 0,
 554                         .len    = 1,
 555                         .buf    = i2c_data,
 556                 },
 557                 {
 558                         .addr   = save_client->addr,
 559                         .flags  = I2C_M_RD,
 560                         .len    = 1,
 561                         .buf    = i2c_buf,
 562                 },
 563         };
 564         struct i2c_msg msgs1[1] = {
 565                 {
 566                         .addr   = save_client->addr,
 567                         .flags  = 0,
 568                         .len    = 2,
 569                         .buf    = i2c_data,
 570                 },
 571         };
 572
 573         i2c_data[0] = 0x09;
 574         i2c_transfer(save_client->adapter, msgs0, 2);
 575
 576         i2c_data[0] = 0x09;
 577         i2c_data[1] = 0x00;
 578         i2c_transfer(save_client->adapter, msgs1, 1);
 579 }
 580
 581 /**
 582  *      wdt_write:
 583  *      @file: file handle to the watchdog
 584  *      @buf: buffer to write (unused as data does not matter here
 585  *      @count: count of bytes
 586  *      @ppos: pointer to the position to write. No seeks allowed
 587  *
 588  *      A write to a watchdog device is defined as a keepalive signal. Any
 589  *      write of data will do, as we we don't define content meaning.
 590  */
 591 static ssize_t wdt_write(struct file *file, const char __user *buf,
 592                          size_t count, loff_t *ppos)
 593 {
 594         if (count) {
 595                 wdt_ping();
 596                 return 1;
 597         }
 598         return 0;
 599 }
 600
 601 static ssize_t wdt_read(struct file *file, char __user *buf,
 602                         size_t count, loff_t *ppos)
 603 {
 604         return 0;
 605 }
 606
 607 /**
 608  *      wdt_ioctl:
 609  *      @inode: inode of the device
 610  *      @file: file handle to the device
 611  *      @cmd: watchdog command
 612  *      @arg: argument pointer
 613  *
 614  *      The watchdog API defines a common set of functions for all watchdogs
 615  *      according to their available features. We only actually usefully support
 616  *      querying capabilities and current status.
 617  */
 618 static int wdt_ioctl(struct file *file, unsigned int cmd,
 619                      unsigned long arg)
 620 {
 621         int new_margin, rv;
 622         static struct watchdog_info ident = {
 623                 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 624                         WDIOF_SETTIMEOUT,
 625                 .firmware_version = 1,
 626                 .identity = "M41T80 WTD"
 627         };
 628
 629         switch (cmd) {
 630         case WDIOC_GETSUPPORT:
 631                 return copy_to_user((struct watchdog_info __user *)arg, &ident,
 632                                     sizeof(ident)) ? -EFAULT : 0;
 633
 634         case WDIOC_GETSTATUS:
 635         case WDIOC_GETBOOTSTATUS:
 636                 return put_user(boot_flag, (int __user *)arg);
 637         case WDIOC_KEEPALIVE:
 638                 wdt_ping();
 639                 return 0;
 640         case WDIOC_SETTIMEOUT:
 641                 if (get_user(new_margin, (int __user *)arg))
 642                         return -EFAULT;
 643                 /* Arbitrary, can't find the card's limits */
 644                 if (new_margin < 1 || new_margin > 124)
 645                         return -EINVAL;
 646                 wdt_margin = new_margin;
 647                 wdt_ping();
 648                 /* Fall */
 649         case WDIOC_GETTIMEOUT:
 650                 return put_user(wdt_margin, (int __user *)arg);
 651
 652         case WDIOC_SETOPTIONS:
 653                 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 654                         return -EFAULT;
 655
 656                 if (rv & WDIOS_DISABLECARD) {
 657                         pr_info("rtc-m41t80: disable watchdog\n");
 658                         wdt_disable();
 659                 }
 660
 661                 if (rv & WDIOS_ENABLECARD) {
 662                         pr_info("rtc-m41t80: enable watchdog\n");
 663                         wdt_ping();
 664                 }
 665
 666                 return -EINVAL;
 667         }
 668         return -ENOTTY;
 669 }
 670
 671 static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 672                                unsigned long arg)
 673 {
 674         int ret;
 675
 676         mutex_lock(&m41t80_rtc_mutex);
 677         ret = wdt_ioctl(file, cmd, arg);
 678         mutex_unlock(&m41t80_rtc_mutex);
 679
 680         return ret;
 681 }
 682
 683 /**
 684  *      wdt_open:
 685  *      @inode: inode of device
 686  *      @file: file handle to device
 687  *
 688  */
 689 static int wdt_open(struct inode *inode, struct file *file)
 690 {
 691         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 692                 mutex_lock(&m41t80_rtc_mutex);
 693                 if (test_and_set_bit(0, &wdt_is_open)) {
 694                         mutex_unlock(&m41t80_rtc_mutex);
 695                         return -EBUSY;
 696                 }
 697                 /*
 698                  *      Activate
 699                  */
 700                 wdt_is_open = 1;
 701                 mutex_unlock(&m41t80_rtc_mutex);
 702                 return nonseekable_open(inode, file);
 703         }
 704         return -ENODEV;
 705 }
 706
 707 /**
 708  *      wdt_close:
 709  *      @inode: inode to board
 710  *      @file: file handle to board
 711  *
 712  */
 713 static int wdt_release(struct inode *inode, struct file *file)
 714 {
 715         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 716                 clear_bit(0, &wdt_is_open);
 717         return 0;
 718 }
 719
 720 /**
 721  *      notify_sys:
 722  *      @this: our notifier block
 723  *      @code: the event being reported
 724  *      @unused: unused
 725  *
 726  *      Our notifier is called on system shutdowns. We want to turn the card
 727  *      off at reboot otherwise the machine will reboot again during memory
 728  *      test or worse yet during the following fsck. This would suck, in fact
 729  *      trust me - if it happens it does suck.
 730  */
 731 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 732                           void *unused)
 733 {
 734         if (code == SYS_DOWN || code == SYS_HALT)
 735                 /* Disable Watchdog */
 736                 wdt_disable();
 737         return NOTIFY_DONE;
 738 }
 739
 740 static const struct file_operations wdt_fops = {
 741         .owner  = THIS_MODULE,
 742         .read   = wdt_read,
 743         .unlocked_ioctl = wdt_unlocked_ioctl,
 744         .write  = wdt_write,
 745         .open   = wdt_open,
 746         .release = wdt_release,
 747         .llseek = no_llseek,
 748 };
 749
 750 static struct miscdevice wdt_dev = {
 751         .minor = WATCHDOG_MINOR,
 752         .name = "watchdog",
 753         .fops = &wdt_fops,
 754 };
 755
 756 /*
 757  *      The WDT card needs to learn about soft shutdowns in order to
 758  *      turn the timebomb registers off.
 759  */
 760 static struct notifier_block wdt_notifier = {
 761         .notifier_call = wdt_notify_sys,
 762 };
 763 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
 764
 765 /*
 766  *****************************************************************************
 767  *
 768  *      Driver Interface
 769  *
 770  *****************************************************************************
 771  */
 772 static int m41t80_probe(struct i2c_client *client,
 773                         const struct i2c_device_id *id)
 774 {
 775         int rc = 0;
 776         struct rtc_device *rtc = NULL;
 777         struct rtc_time tm;
 778         struct m41t80_data *clientdata = NULL;
 779
 780         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
 781                                      | I2C_FUNC_SMBUS_BYTE_DATA)) {
 782                 rc = -ENODEV;
 783                 goto exit;
 784         }
 785
 786         dev_info(&client->dev,
 787                  "chip found, driver version " DRV_VERSION "\n");
 788
 789         clientdata = kzalloc(sizeof(*clientdata), GFP_KERNEL);
 790         if (!clientdata) {
 791                 rc = -ENOMEM;
 792                 goto exit;
 793         }
 794
 795         clientdata->features = id->driver_data;
 796         i2c_set_clientdata(client, clientdata);
 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
 808         /* Make sure HT (Halt Update) bit is cleared */
 809         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 810         if (rc < 0)
 811                 goto ht_err;
 812
 813         if (rc & M41T80_ALHOUR_HT) {
 814                 if (clientdata->features & M41T80_FEATURE_HT) {
 815                         m41t80_get_datetime(client, &tm);
 816                         dev_info(&client->dev, "HT bit was set!\n");
 817                         dev_info(&client->dev,
 818                                  "Power Down at "
 819                                  "%04i-%02i-%02i %02i:%02i:%02i\n",
 820                                  tm.tm_year + 1900,
 821                                  tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
 822                                  tm.tm_min, tm.tm_sec);
 823                 }
 824                 if (i2c_smbus_write_byte_data(client,
 825                                               M41T80_REG_ALARM_HOUR,
 826                                               rc & ~M41T80_ALHOUR_HT) < 0)
 827                         goto ht_err;
 828         }
 829
 830         /* Make sure ST (stop) bit is cleared */
 831         rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 832         if (rc < 0)
 833                 goto st_err;
 834
 835         if (rc & M41T80_SEC_ST) {
 836                 if (i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 837                                               rc & ~M41T80_SEC_ST) < 0)
 838                         goto st_err;
 839         }
 840
 841         rc = m41t80_sysfs_register(&client->dev);
 842         if (rc)
 843                 goto exit;
 844
 845 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 846         if (clientdata->features & M41T80_FEATURE_HT) {
 847                 save_client = client;
 848                 rc = misc_register(&wdt_dev);
 849                 if (rc)
 850                         goto exit;
 851                 rc = register_reboot_notifier(&wdt_notifier);
 852                 if (rc) {
 853                         misc_deregister(&wdt_dev);
 854                         goto exit;
 855                 }
 856         }
 857 #endif
 858         return 0;
 859
 860 st_err:
 861         rc = -EIO;
 862         dev_err(&client->dev, "Can't clear ST bit\n");
 863         goto exit;
 864 ht_err:
 865         rc = -EIO;
 866         dev_err(&client->dev, "Can't clear HT bit\n");
 867         goto exit;
 868
 869 exit:
 870         if (rtc)
 871                 rtc_device_unregister(rtc);
 872         kfree(clientdata);
 873         return rc;
 874 }
 875
 876 static int m41t80_remove(struct i2c_client *client)
 877 {
 878         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 879         struct rtc_device *rtc = clientdata->rtc;
 880
 881 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 882         if (clientdata->features & M41T80_FEATURE_HT) {
 883                 misc_deregister(&wdt_dev);
 884                 unregister_reboot_notifier(&wdt_notifier);
 885         }
 886 #endif
 887         if (rtc)
 888                 rtc_device_unregister(rtc);
 889         kfree(clientdata);
 890
 891         return 0;
 892 }
 893
 894 static struct i2c_driver m41t80_driver = {
 895         .driver = {
 896                 .name = "rtc-m41t80",
 897         },
 898         .probe = m41t80_probe,
 899         .remove = m41t80_remove,
 900         .id_table = m41t80_id,
 901 };
 902
 903 static int __init m41t80_rtc_init(void)
 904 {
 905         return i2c_add_driver(&m41t80_driver);
 906 }
 907
 908 static void __exit m41t80_rtc_exit(void)
 909 {
 910         i2c_del_driver(&m41t80_driver);
 911 }
 912
 913 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
 914 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
 915 MODULE_LICENSE("GPL");
 916 MODULE_VERSION(DRV_VERSION);
 917
 918 module_init(m41t80_rtc_init);
 919 module_exit(m41t80_rtc_exit);