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/module.h>
  17 #include <linux/init.h>
  18 #include <linux/slab.h>
  19 #include <linux/string.h>
  20 #include <linux/i2c.h>
  21 #include <linux/rtc.h>
  22 #include <linux/bcd.h>
  23 #ifdef CONFIG_RTC_DRV_M41T80_WDT
  24 #include <linux/miscdevice.h>
  25 #include <linux/watchdog.h>
  26 #include <linux/reboot.h>
  27 #include <linux/fs.h>
  28 #include <linux/ioctl.h>
  29 #endif
  30
  31 #define M41T80_REG_SSEC 0
  32 #define M41T80_REG_SEC  1
  33 #define M41T80_REG_MIN  2
  34 #define M41T80_REG_HOUR 3
  35 #define M41T80_REG_WDAY 4
  36 #define M41T80_REG_DAY  5
  37 #define M41T80_REG_MON  6
  38 #define M41T80_REG_YEAR 7
  39 #define M41T80_REG_ALARM_MON    0xa
  40 #define M41T80_REG_ALARM_DAY    0xb
  41 #define M41T80_REG_ALARM_HOUR   0xc
  42 #define M41T80_REG_ALARM_MIN    0xd
  43 #define M41T80_REG_ALARM_SEC    0xe
  44 #define M41T80_REG_FLAGS        0xf
  45 #define M41T80_REG_SQW  0x13
  46
  47 #define M41T80_DATETIME_REG_SIZE        (M41T80_REG_YEAR + 1)
  48 #define M41T80_ALARM_REG_SIZE   \
  49         (M41T80_REG_ALARM_SEC + 1 - M41T80_REG_ALARM_MON)
  50
  51 #define M41T80_SEC_ST           (1 << 7)        /* ST: Stop Bit */
  52 #define M41T80_ALMON_AFE        (1 << 7)        /* AFE: AF Enable Bit */
  53 #define M41T80_ALMON_SQWE       (1 << 6)        /* SQWE: SQW Enable Bit */
  54 #define M41T80_ALHOUR_HT        (1 << 6)        /* HT: Halt Update Bit */
  55 #define M41T80_FLAGS_AF         (1 << 6)        /* AF: Alarm Flag Bit */
  56 #define M41T80_FLAGS_BATT_LOW   (1 << 4)        /* BL: Battery Low Bit */
  57
  58 #define M41T80_FEATURE_HT       (1 << 0)
  59 #define M41T80_FEATURE_BL       (1 << 1)
  60
  61 #define DRV_VERSION "0.05"
  62
  63 struct m41t80_chip_info {
  64         const char *name;
  65         u8 features;
  66 };
  67
  68 static const struct m41t80_chip_info m41t80_chip_info_tbl[] = {
  69         {
  70                 .name           = "m41t80",
  71                 .features       = 0,
  72         },
  73         {
  74                 .name           = "m41t81",
  75                 .features       = M41T80_FEATURE_HT,
  76         },
  77         {
  78                 .name           = "m41t81s",
  79                 .features       = M41T80_FEATURE_HT | M41T80_FEATURE_BL,
  80         },
  81         {
  82                 .name           = "m41t82",
  83                 .features       = M41T80_FEATURE_HT | M41T80_FEATURE_BL,
  84         },
  85         {
  86                 .name           = "m41t83",
  87                 .features       = M41T80_FEATURE_HT | M41T80_FEATURE_BL,
  88         },
  89         {
  90                 .name           = "m41st84",
  91                 .features       = M41T80_FEATURE_HT | M41T80_FEATURE_BL,
  92         },
  93         {
  94                 .name           = "m41st85",
  95                 .features       = M41T80_FEATURE_HT | M41T80_FEATURE_BL,
  96         },
  97         {
  98                 .name           = "m41st87",
  99                 .features       = M41T80_FEATURE_HT | M41T80_FEATURE_BL,
 100         },
 101 };
 102
 103 struct m41t80_data {
 104         const struct m41t80_chip_info *chip;
 105         struct rtc_device *rtc;
 106 };
 107
 108 static int m41t80_get_datetime(struct i2c_client *client,
 109                                struct rtc_time *tm)
 110 {
 111         u8 buf[M41T80_DATETIME_REG_SIZE], dt_addr[1] = { M41T80_REG_SEC };
 112         struct i2c_msg msgs[] = {
 113                 {
 114                         .addr   = client->addr,
 115                         .flags  = 0,
 116                         .len    = 1,
 117                         .buf    = dt_addr,
 118                 },
 119                 {
 120                         .addr   = client->addr,
 121                         .flags  = I2C_M_RD,
 122                         .len    = M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
 123                         .buf    = buf + M41T80_REG_SEC,
 124                 },
 125         };
 126
 127         if (i2c_transfer(client->adapter, msgs, 2) < 0) {
 128                 dev_err(&client->dev, "read error\n");
 129                 return -EIO;
 130         }
 131
 132         tm->tm_sec = BCD2BIN(buf[M41T80_REG_SEC] & 0x7f);
 133         tm->tm_min = BCD2BIN(buf[M41T80_REG_MIN] & 0x7f);
 134         tm->tm_hour = BCD2BIN(buf[M41T80_REG_HOUR] & 0x3f);
 135         tm->tm_mday = BCD2BIN(buf[M41T80_REG_DAY] & 0x3f);
 136         tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
 137         tm->tm_mon = BCD2BIN(buf[M41T80_REG_MON] & 0x1f) - 1;
 138
 139         /* assume 20YY not 19YY, and ignore the Century Bit */
 140         tm->tm_year = BCD2BIN(buf[M41T80_REG_YEAR]) + 100;
 141         return 0;
 142 }
 143
 144 /* Sets the given date and time to the real time clock. */
 145 static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 146 {
 147         u8 wbuf[1 + M41T80_DATETIME_REG_SIZE];
 148         u8 *buf = &wbuf[1];
 149         u8 dt_addr[1] = { M41T80_REG_SEC };
 150         struct i2c_msg msgs_in[] = {
 151                 {
 152                         .addr   = client->addr,
 153                         .flags  = 0,
 154                         .len    = 1,
 155                         .buf    = dt_addr,
 156                 },
 157                 {
 158                         .addr   = client->addr,
 159                         .flags  = I2C_M_RD,
 160                         .len    = M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
 161                         .buf    = buf + M41T80_REG_SEC,
 162                 },
 163         };
 164         struct i2c_msg msgs[] = {
 165                 {
 166                         .addr   = client->addr,
 167                         .flags  = 0,
 168                         .len    = 1 + M41T80_DATETIME_REG_SIZE,
 169                         .buf    = wbuf,
 170                  },
 171         };
 172
 173         /* Read current reg values into buf[1..7] */
 174         if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
 175                 dev_err(&client->dev, "read error\n");
 176                 return -EIO;
 177         }
 178
 179         wbuf[0] = 0; /* offset into rtc's regs */
 180         /* Merge time-data and register flags into buf[0..7] */
 181         buf[M41T80_REG_SSEC] = 0;
 182         buf[M41T80_REG_SEC] =
 183                 BIN2BCD(tm->tm_sec) | (buf[M41T80_REG_SEC] & ~0x7f);
 184         buf[M41T80_REG_MIN] =
 185                 BIN2BCD(tm->tm_min) | (buf[M41T80_REG_MIN] & ~0x7f);
 186         buf[M41T80_REG_HOUR] =
 187                 BIN2BCD(tm->tm_hour) | (buf[M41T80_REG_HOUR] & ~0x3f) ;
 188         buf[M41T80_REG_WDAY] =
 189                 (tm->tm_wday & 0x07) | (buf[M41T80_REG_WDAY] & ~0x07);
 190         buf[M41T80_REG_DAY] =
 191                 BIN2BCD(tm->tm_mday) | (buf[M41T80_REG_DAY] & ~0x3f);
 192         buf[M41T80_REG_MON] =
 193                 BIN2BCD(tm->tm_mon + 1) | (buf[M41T80_REG_MON] & ~0x1f);
 194         /* assume 20YY not 19YY */
 195         buf[M41T80_REG_YEAR] = BIN2BCD(tm->tm_year % 100);
 196
 197         if (i2c_transfer(client->adapter, msgs, 1) != 1) {
 198                 dev_err(&client->dev, "write error\n");
 199                 return -EIO;
 200         }
 201         return 0;
 202 }
 203
 204 #if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
 205 static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
 206 {
 207         struct i2c_client *client = to_i2c_client(dev);
 208         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 209         u8 reg;
 210
 211         if (clientdata->chip->features & M41T80_FEATURE_BL) {
 212                 reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 213                 seq_printf(seq, "battery\t\t: %s\n",
 214                            (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
 215         }
 216         return 0;
 217 }
 218 #else
 219 #define m41t80_rtc_proc NULL
 220 #endif
 221
 222 static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
 223 {
 224         return m41t80_get_datetime(to_i2c_client(dev), tm);
 225 }
 226
 227 static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
 228 {
 229         return m41t80_set_datetime(to_i2c_client(dev), tm);
 230 }
 231
 232 #if defined(CONFIG_RTC_INTF_DEV) || defined(CONFIG_RTC_INTF_DEV_MODULE)
 233 static int
 234 m41t80_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 235 {
 236         struct i2c_client *client = to_i2c_client(dev);
 237         int rc;
 238
 239         switch (cmd) {
 240         case RTC_AIE_OFF:
 241         case RTC_AIE_ON:
 242                 break;
 243         default:
 244                 return -ENOIOCTLCMD;
 245         }
 246
 247         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 248         if (rc < 0)
 249                 goto err;
 250         switch (cmd) {
 251         case RTC_AIE_OFF:
 252                 rc &= ~M41T80_ALMON_AFE;
 253                 break;
 254         case RTC_AIE_ON:
 255                 rc |= M41T80_ALMON_AFE;
 256                 break;
 257         }
 258         if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, rc) < 0)
 259                 goto err;
 260         return 0;
 261 err:
 262         return -EIO;
 263 }
 264 #else
 265 #define m41t80_rtc_ioctl NULL
 266 #endif
 267
 268 static int m41t80_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 269 {
 270         struct i2c_client *client = to_i2c_client(dev);
 271         u8 wbuf[1 + M41T80_ALARM_REG_SIZE];
 272         u8 *buf = &wbuf[1];
 273         u8 *reg = buf - M41T80_REG_ALARM_MON;
 274         u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
 275         struct i2c_msg msgs_in[] = {
 276                 {
 277                         .addr   = client->addr,
 278                         .flags  = 0,
 279                         .len    = 1,
 280                         .buf    = dt_addr,
 281                 },
 282                 {
 283                         .addr   = client->addr,
 284                         .flags  = I2C_M_RD,
 285                         .len    = M41T80_ALARM_REG_SIZE,
 286                         .buf    = buf,
 287                 },
 288         };
 289         struct i2c_msg msgs[] = {
 290                 {
 291                         .addr   = client->addr,
 292                         .flags  = 0,
 293                         .len    = 1 + M41T80_ALARM_REG_SIZE,
 294                         .buf    = wbuf,
 295                  },
 296         };
 297
 298         if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
 299                 dev_err(&client->dev, "read error\n");
 300                 return -EIO;
 301         }
 302         reg[M41T80_REG_ALARM_MON] &= ~(0x1f | M41T80_ALMON_AFE);
 303         reg[M41T80_REG_ALARM_DAY] = 0;
 304         reg[M41T80_REG_ALARM_HOUR] &= ~(0x3f | 0x80);
 305         reg[M41T80_REG_ALARM_MIN] = 0;
 306         reg[M41T80_REG_ALARM_SEC] = 0;
 307
 308         wbuf[0] = M41T80_REG_ALARM_MON; /* offset into rtc's regs */
 309         reg[M41T80_REG_ALARM_SEC] |= t->time.tm_sec >= 0 ?
 310                 BIN2BCD(t->time.tm_sec) : 0x80;
 311         reg[M41T80_REG_ALARM_MIN] |= t->time.tm_min >= 0 ?
 312                 BIN2BCD(t->time.tm_min) : 0x80;
 313         reg[M41T80_REG_ALARM_HOUR] |= t->time.tm_hour >= 0 ?
 314                 BIN2BCD(t->time.tm_hour) : 0x80;
 315         reg[M41T80_REG_ALARM_DAY] |= t->time.tm_mday >= 0 ?
 316                 BIN2BCD(t->time.tm_mday) : 0x80;
 317         if (t->time.tm_mon >= 0)
 318                 reg[M41T80_REG_ALARM_MON] |= BIN2BCD(t->time.tm_mon + 1);
 319         else
 320                 reg[M41T80_REG_ALARM_DAY] |= 0x40;
 321
 322         if (i2c_transfer(client->adapter, msgs, 1) != 1) {
 323                 dev_err(&client->dev, "write error\n");
 324                 return -EIO;
 325         }
 326
 327         if (t->enabled) {
 328                 reg[M41T80_REG_ALARM_MON] |= M41T80_ALMON_AFE;
 329                 if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 330                                               reg[M41T80_REG_ALARM_MON]) < 0) {
 331                         dev_err(&client->dev, "write error\n");
 332                         return -EIO;
 333                 }
 334         }
 335         return 0;
 336 }
 337
 338 static int m41t80_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 339 {
 340         struct i2c_client *client = to_i2c_client(dev);
 341         u8 buf[M41T80_ALARM_REG_SIZE + 1]; /* all alarm regs and flags */
 342         u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
 343         u8 *reg = buf - M41T80_REG_ALARM_MON;
 344         struct i2c_msg msgs[] = {
 345                 {
 346                         .addr   = client->addr,
 347                         .flags  = 0,
 348                         .len    = 1,
 349                         .buf    = dt_addr,
 350                 },
 351                 {
 352                         .addr   = client->addr,
 353                         .flags  = I2C_M_RD,
 354                         .len    = M41T80_ALARM_REG_SIZE + 1,
 355                         .buf    = buf,
 356                 },
 357         };
 358
 359         if (i2c_transfer(client->adapter, msgs, 2) < 0) {
 360                 dev_err(&client->dev, "read error\n");
 361                 return -EIO;
 362         }
 363         t->time.tm_sec = -1;
 364         t->time.tm_min = -1;
 365         t->time.tm_hour = -1;
 366         t->time.tm_mday = -1;
 367         t->time.tm_mon = -1;
 368         if (!(reg[M41T80_REG_ALARM_SEC] & 0x80))
 369                 t->time.tm_sec = BCD2BIN(reg[M41T80_REG_ALARM_SEC] & 0x7f);
 370         if (!(reg[M41T80_REG_ALARM_MIN] & 0x80))
 371                 t->time.tm_min = BCD2BIN(reg[M41T80_REG_ALARM_MIN] & 0x7f);
 372         if (!(reg[M41T80_REG_ALARM_HOUR] & 0x80))
 373                 t->time.tm_hour = BCD2BIN(reg[M41T80_REG_ALARM_HOUR] & 0x3f);
 374         if (!(reg[M41T80_REG_ALARM_DAY] & 0x80))
 375                 t->time.tm_mday = BCD2BIN(reg[M41T80_REG_ALARM_DAY] & 0x3f);
 376         if (!(reg[M41T80_REG_ALARM_DAY] & 0x40))
 377                 t->time.tm_mon = BCD2BIN(reg[M41T80_REG_ALARM_MON] & 0x1f) - 1;
 378         t->time.tm_year = -1;
 379         t->time.tm_wday = -1;
 380         t->time.tm_yday = -1;
 381         t->time.tm_isdst = -1;
 382         t->enabled = !!(reg[M41T80_REG_ALARM_MON] & M41T80_ALMON_AFE);
 383         t->pending = !!(reg[M41T80_REG_FLAGS] & M41T80_FLAGS_AF);
 384         return 0;
 385 }
 386
 387 static struct rtc_class_ops m41t80_rtc_ops = {
 388         .read_time = m41t80_rtc_read_time,
 389         .set_time = m41t80_rtc_set_time,
 390         .read_alarm = m41t80_rtc_read_alarm,
 391         .set_alarm = m41t80_rtc_set_alarm,
 392         .proc = m41t80_rtc_proc,
 393         .ioctl = m41t80_rtc_ioctl,
 394 };
 395
 396 #if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
 397 static ssize_t m41t80_sysfs_show_flags(struct device *dev,
 398                                 struct device_attribute *attr, char *buf)
 399 {
 400         struct i2c_client *client = to_i2c_client(dev);
 401         int val;
 402
 403         val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 404         if (val < 0)
 405                 return -EIO;
 406         return sprintf(buf, "%#x\n", val);
 407 }
 408 static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
 409
 410 static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
 411                                 struct device_attribute *attr, char *buf)
 412 {
 413         struct i2c_client *client = to_i2c_client(dev);
 414         int val;
 415
 416         val = i2c_smbus_read_byte_data(client, M41T80_REG_SQW);
 417         if (val < 0)
 418                 return -EIO;
 419         val = (val >> 4) & 0xf;
 420         switch (val) {
 421         case 0:
 422                 break;
 423         case 1:
 424                 val = 32768;
 425                 break;
 426         default:
 427                 val = 32768 >> val;
 428         }
 429         return sprintf(buf, "%d\n", val);
 430 }
 431 static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
 432                                 struct device_attribute *attr,
 433                                 const char *buf, size_t count)
 434 {
 435         struct i2c_client *client = to_i2c_client(dev);
 436         int almon, sqw;
 437         int val = simple_strtoul(buf, NULL, 0);
 438
 439         if (val) {
 440                 if (!is_power_of_2(val))
 441                         return -EINVAL;
 442                 val = ilog2(val);
 443                 if (val == 15)
 444                         val = 1;
 445                 else if (val < 14)
 446                         val = 15 - val;
 447                 else
 448                         return -EINVAL;
 449         }
 450         /* disable SQW, set SQW frequency & re-enable */
 451         almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 452         if (almon < 0)
 453                 return -EIO;
 454         sqw = i2c_smbus_read_byte_data(client, M41T80_REG_SQW);
 455         if (sqw < 0)
 456                 return -EIO;
 457         sqw = (sqw & 0x0f) | (val << 4);
 458         if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 459                                       almon & ~M41T80_ALMON_SQWE) < 0 ||
 460             i2c_smbus_write_byte_data(client, M41T80_REG_SQW, sqw) < 0)
 461                 return -EIO;
 462         if (val && i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 463                                              almon | M41T80_ALMON_SQWE) < 0)
 464                 return -EIO;
 465         return count;
 466 }
 467 static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
 468                    m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
 469
 470 static struct attribute *attrs[] = {
 471         &dev_attr_flags.attr,
 472         &dev_attr_sqwfreq.attr,
 473         NULL,
 474 };
 475 static struct attribute_group attr_group = {
 476         .attrs = attrs,
 477 };
 478
 479 static int m41t80_sysfs_register(struct device *dev)
 480 {
 481         return sysfs_create_group(&dev->kobj, &attr_group);
 482 }
 483 #else
 484 static int m41t80_sysfs_register(struct device *dev)
 485 {
 486         return 0;
 487 }
 488 #endif
 489
 490 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 491 /*
 492  *****************************************************************************
 493  *
 494  * Watchdog Driver
 495  *
 496  *****************************************************************************
 497  */
 498 static struct i2c_client *save_client;
 499
 500 /* Default margin */
 501 #define WD_TIMO 60              /* 1..31 seconds */
 502
 503 static int wdt_margin = WD_TIMO;
 504 module_param(wdt_margin, int, 0);
 505 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 506
 507 static unsigned long wdt_is_open;
 508 static int boot_flag;
 509
 510 /**
 511  *      wdt_ping:
 512  *
 513  *      Reload counter one with the watchdog timeout. We don't bother reloading
 514  *      the cascade counter.
 515  */
 516 static void wdt_ping(void)
 517 {
 518         unsigned char i2c_data[2];
 519         struct i2c_msg msgs1[1] = {
 520                 {
 521                         .addr   = save_client->addr,
 522                         .flags  = 0,
 523                         .len    = 2,
 524                         .buf    = i2c_data,
 525                 },
 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         i2c_transfer(save_client->adapter, msgs1, 1);
 538 }
 539
 540 /**
 541  *      wdt_disable:
 542  *
 543  *      disables watchdog.
 544  */
 545 static void wdt_disable(void)
 546 {
 547         unsigned char i2c_data[2], i2c_buf[0x10];
 548         struct i2c_msg msgs0[2] = {
 549                 {
 550                         .addr   = save_client->addr,
 551                         .flags  = 0,
 552                         .len    = 1,
 553                         .buf    = i2c_data,
 554                 },
 555                 {
 556                         .addr   = save_client->addr,
 557                         .flags  = I2C_M_RD,
 558                         .len    = 1,
 559                         .buf    = i2c_buf,
 560                 },
 561         };
 562         struct i2c_msg msgs1[1] = {
 563                 {
 564                         .addr   = save_client->addr,
 565                         .flags  = 0,
 566                         .len    = 2,
 567                         .buf    = i2c_data,
 568                 },
 569         };
 570
 571         i2c_data[0] = 0x09;
 572         i2c_transfer(save_client->adapter, msgs0, 2);
 573
 574         i2c_data[0] = 0x09;
 575         i2c_data[1] = 0x00;
 576         i2c_transfer(save_client->adapter, msgs1, 1);
 577 }
 578
 579 /**
 580  *      wdt_write:
 581  *      @file: file handle to the watchdog
 582  *      @buf: buffer to write (unused as data does not matter here
 583  *      @count: count of bytes
 584  *      @ppos: pointer to the position to write. No seeks allowed
 585  *
 586  *      A write to a watchdog device is defined as a keepalive signal. Any
 587  *      write of data will do, as we we don't define content meaning.
 588  */
 589 static ssize_t wdt_write(struct file *file, const char __user *buf,
 590                          size_t count, loff_t *ppos)
 591 {
 592         /*  Can't seek (pwrite) on this device
 593         if (ppos != &file->f_pos)
 594         return -ESPIPE;
 595         */
 596         if (count) {
 597                 wdt_ping();
 598                 return 1;
 599         }
 600         return 0;
 601 }
 602
 603 static ssize_t wdt_read(struct file *file, char __user *buf,
 604                         size_t count, loff_t *ppos)
 605 {
 606         return 0;
 607 }
 608
 609 /**
 610  *      wdt_ioctl:
 611  *      @inode: inode of the device
 612  *      @file: file handle to the device
 613  *      @cmd: watchdog command
 614  *      @arg: argument pointer
 615  *
 616  *      The watchdog API defines a common set of functions for all watchdogs
 617  *      according to their available features. We only actually usefully support
 618  *      querying capabilities and current status.
 619  */
 620 static int wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 621                      unsigned long arg)
 622 {
 623         int new_margin, rv;
 624         static struct watchdog_info ident = {
 625                 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 626                         WDIOF_SETTIMEOUT,
 627                 .firmware_version = 1,
 628                 .identity = "M41T80 WTD"
 629         };
 630
 631         switch (cmd) {
 632         case WDIOC_GETSUPPORT:
 633                 return copy_to_user((struct watchdog_info __user *)arg, &ident,
 634                                     sizeof(ident)) ? -EFAULT : 0;
 635
 636         case WDIOC_GETSTATUS:
 637         case WDIOC_GETBOOTSTATUS:
 638                 return put_user(boot_flag, (int __user *)arg);
 639         case WDIOC_KEEPALIVE:
 640                 wdt_ping();
 641                 return 0;
 642         case WDIOC_SETTIMEOUT:
 643                 if (get_user(new_margin, (int __user *)arg))
 644                         return -EFAULT;
 645                 /* Arbitrary, can't find the card's limits */
 646                 if (new_margin < 1 || new_margin > 124)
 647                         return -EINVAL;
 648                 wdt_margin = new_margin;
 649                 wdt_ping();
 650                 /* Fall */
 651         case WDIOC_GETTIMEOUT:
 652                 return put_user(wdt_margin, (int __user *)arg);
 653
 654         case WDIOC_SETOPTIONS:
 655                 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 656                         return -EFAULT;
 657
 658                 if (rv & WDIOS_DISABLECARD) {
 659                         printk(KERN_INFO
 660                                "rtc-m41t80: disable watchdog\n");
 661                         wdt_disable();
 662                 }
 663
 664                 if (rv & WDIOS_ENABLECARD) {
 665                         printk(KERN_INFO
 666                                "rtc-m41t80: enable watchdog\n");
 667                         wdt_ping();
 668                 }
 669
 670                 return -EINVAL;
 671         }
 672         return -ENOTTY;
 673 }
 674
 675 /**
 676  *      wdt_open:
 677  *      @inode: inode of device
 678  *      @file: file handle to device
 679  *
 680  */
 681 static int wdt_open(struct inode *inode, struct file *file)
 682 {
 683         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 684                 if (test_and_set_bit(0, &wdt_is_open))
 685                         return -EBUSY;
 686                 /*
 687                  *      Activate
 688                  */
 689                 wdt_is_open = 1;
 690                 return 0;
 691         }
 692         return -ENODEV;
 693 }
 694
 695 /**
 696  *      wdt_close:
 697  *      @inode: inode to board
 698  *      @file: file handle to board
 699  *
 700  */
 701 static int wdt_release(struct inode *inode, struct file *file)
 702 {
 703         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 704                 clear_bit(0, &wdt_is_open);
 705         return 0;
 706 }
 707
 708 /**
 709  *      notify_sys:
 710  *      @this: our notifier block
 711  *      @code: the event being reported
 712  *      @unused: unused
 713  *
 714  *      Our notifier is called on system shutdowns. We want to turn the card
 715  *      off at reboot otherwise the machine will reboot again during memory
 716  *      test or worse yet during the following fsck. This would suck, in fact
 717  *      trust me - if it happens it does suck.
 718  */
 719 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 720                           void *unused)
 721 {
 722         if (code == SYS_DOWN || code == SYS_HALT)
 723                 /* Disable Watchdog */
 724                 wdt_disable();
 725         return NOTIFY_DONE;
 726 }
 727
 728 static const struct file_operations wdt_fops = {
 729         .owner  = THIS_MODULE,
 730         .read   = wdt_read,
 731         .ioctl  = wdt_ioctl,
 732         .write  = wdt_write,
 733         .open   = wdt_open,
 734         .release = wdt_release,
 735 };
 736
 737 static struct miscdevice wdt_dev = {
 738         .minor = WATCHDOG_MINOR,
 739         .name = "watchdog",
 740         .fops = &wdt_fops,
 741 };
 742
 743 /*
 744  *      The WDT card needs to learn about soft shutdowns in order to
 745  *      turn the timebomb registers off.
 746  */
 747 static struct notifier_block wdt_notifier = {
 748         .notifier_call = wdt_notify_sys,
 749 };
 750 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
 751
 752 /*
 753  *****************************************************************************
 754  *
 755  *      Driver Interface
 756  *
 757  *****************************************************************************
 758  */
 759 static int m41t80_probe(struct i2c_client *client)
 760 {
 761         int i, rc = 0;
 762         struct rtc_device *rtc = NULL;
 763         struct rtc_time tm;
 764         const struct m41t80_chip_info *chip;
 765         struct m41t80_data *clientdata = NULL;
 766
 767         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
 768                                      | I2C_FUNC_SMBUS_BYTE_DATA)) {
 769                 rc = -ENODEV;
 770                 goto exit;
 771         }
 772
 773         dev_info(&client->dev,
 774                  "chip found, driver version " DRV_VERSION "\n");
 775
 776         chip = NULL;
 777         for (i = 0; i < ARRAY_SIZE(m41t80_chip_info_tbl); i++) {
 778                 if (!strcmp(m41t80_chip_info_tbl[i].name, client->name)) {
 779                         chip = &m41t80_chip_info_tbl[i];
 780                         break;
 781                 }
 782         }
 783         if (!chip) {
 784                 dev_err(&client->dev, "%s is not supported\n", client->name);
 785                 rc = -ENODEV;
 786                 goto exit;
 787         }
 788
 789         clientdata = kzalloc(sizeof(*clientdata), GFP_KERNEL);
 790         if (!clientdata) {
 791                 rc = -ENOMEM;
 792                 goto exit;
 793         }
 794
 795         rtc = rtc_device_register(client->name, &client->dev,
 796                                   &m41t80_rtc_ops, THIS_MODULE);
 797         if (IS_ERR(rtc)) {
 798                 rc = PTR_ERR(rtc);
 799                 rtc = NULL;
 800                 goto exit;
 801         }
 802
 803         clientdata->rtc = rtc;
 804         clientdata->chip = chip;
 805         i2c_set_clientdata(client, clientdata);
 806
 807         /* Make sure HT (Halt Update) bit is cleared */
 808         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 809         if (rc < 0)
 810                 goto ht_err;
 811
 812         if (rc & M41T80_ALHOUR_HT) {
 813                 if (chip->features & M41T80_FEATURE_HT) {
 814                         m41t80_get_datetime(client, &tm);
 815                         dev_info(&client->dev, "HT bit was set!\n");
 816                         dev_info(&client->dev,
 817                                  "Power Down at "
 818                                  "%04i-%02i-%02i %02i:%02i:%02i\n",
 819                                  tm.tm_year + 1900,
 820                                  tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
 821                                  tm.tm_min, tm.tm_sec);
 822                 }
 823                 if (i2c_smbus_write_byte_data(client,
 824                                               M41T80_REG_ALARM_HOUR,
 825                                               rc & ~M41T80_ALHOUR_HT) < 0)
 826                         goto ht_err;
 827         }
 828
 829         /* Make sure ST (stop) bit is cleared */
 830         rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 831         if (rc < 0)
 832                 goto st_err;
 833
 834         if (rc & M41T80_SEC_ST) {
 835                 if (i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 836                                               rc & ~M41T80_SEC_ST) < 0)
 837                         goto st_err;
 838         }
 839
 840         rc = m41t80_sysfs_register(&client->dev);
 841         if (rc)
 842                 goto exit;
 843
 844 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 845         if (chip->features & M41T80_FEATURE_HT) {
 846                 rc = misc_register(&wdt_dev);
 847                 if (rc)
 848                         goto exit;
 849                 rc = register_reboot_notifier(&wdt_notifier);
 850                 if (rc) {
 851                         misc_deregister(&wdt_dev);
 852                         goto exit;
 853                 }
 854                 save_client = client;
 855         }
 856 #endif
 857         return 0;
 858
 859 st_err:
 860         rc = -EIO;
 861         dev_err(&client->dev, "Can't clear ST bit\n");
 862         goto exit;
 863 ht_err:
 864         rc = -EIO;
 865         dev_err(&client->dev, "Can't clear HT bit\n");
 866         goto exit;
 867
 868 exit:
 869         if (rtc)
 870                 rtc_device_unregister(rtc);
 871         kfree(clientdata);
 872         return rc;
 873 }
 874
 875 static int m41t80_remove(struct i2c_client *client)
 876 {
 877         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 878         struct rtc_device *rtc = clientdata->rtc;
 879
 880 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 881         if (clientdata->chip->features & M41T80_FEATURE_HT) {
 882                 misc_deregister(&wdt_dev);
 883                 unregister_reboot_notifier(&wdt_notifier);
 884         }
 885 #endif
 886         if (rtc)
 887                 rtc_device_unregister(rtc);
 888         kfree(clientdata);
 889
 890         return 0;
 891 }
 892
 893 static struct i2c_driver m41t80_driver = {
 894         .driver = {
 895                 .name = "rtc-m41t80",
 896         },
 897         .probe = m41t80_probe,
 898         .remove = m41t80_remove,
 899 };
 900
 901 static int __init m41t80_rtc_init(void)
 902 {
 903         return i2c_add_driver(&m41t80_driver);
 904 }
 905
 906 static void __exit m41t80_rtc_exit(void)
 907 {
 908         i2c_del_driver(&m41t80_driver);
 909 }
 910
 911 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
 912 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
 913 MODULE_LICENSE("GPL");
 914 MODULE_VERSION(DRV_VERSION);
 915
 916 module_init(m41t80_rtc_init);
 917 module_exit(m41t80_rtc_exit);