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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  17
  18 #include <linux/bcd.h>
  19 #include <linux/i2c.h>
  20 #include <linux/init.h>
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/rtc.h>
  24 #include <linux/slab.h>
  25 #include <linux/mutex.h>
  26 #include <linux/string.h>
  27 #ifdef CONFIG_RTC_DRV_M41T80_WDT
  28 #include <linux/fs.h>
  29 #include <linux/ioctl.h>
  30 #include <linux/miscdevice.h>
  31 #include <linux/reboot.h>
  32 #include <linux/watchdog.h>
  33 #endif
  34
  35 #define M41T80_REG_SSEC         0x00
  36 #define M41T80_REG_SEC          0x01
  37 #define M41T80_REG_MIN          0x02
  38 #define M41T80_REG_HOUR         0x03
  39 #define M41T80_REG_WDAY         0x04
  40 #define M41T80_REG_DAY          0x05
  41 #define M41T80_REG_MON          0x06
  42 #define M41T80_REG_YEAR         0x07
  43 #define M41T80_REG_ALARM_MON    0x0a
  44 #define M41T80_REG_ALARM_DAY    0x0b
  45 #define M41T80_REG_ALARM_HOUR   0x0c
  46 #define M41T80_REG_ALARM_MIN    0x0d
  47 #define M41T80_REG_ALARM_SEC    0x0e
  48 #define M41T80_REG_FLAGS        0x0f
  49 #define M41T80_REG_SQW          0x13
  50
  51 #define M41T80_DATETIME_REG_SIZE        (M41T80_REG_YEAR + 1)
  52 #define M41T80_ALARM_REG_SIZE   \
  53         (M41T80_REG_ALARM_SEC + 1 - M41T80_REG_ALARM_MON)
  54
  55 #define M41T80_SEC_ST           BIT(7)  /* ST: Stop Bit */
  56 #define M41T80_ALMON_AFE        BIT(7)  /* AFE: AF Enable Bit */
  57 #define M41T80_ALMON_SQWE       BIT(6)  /* SQWE: SQW Enable Bit */
  58 #define M41T80_ALHOUR_HT        BIT(6)  /* HT: Halt Update Bit */
  59 #define M41T80_FLAGS_OF         BIT(2)  /* OF: Oscillator Failure Bit */
  60 #define M41T80_FLAGS_AF         BIT(6)  /* AF: Alarm Flag Bit */
  61 #define M41T80_FLAGS_BATT_LOW   BIT(4)  /* BL: Battery Low Bit */
  62 #define M41T80_WATCHDOG_RB2     BIT(7)  /* RB: Watchdog resolution */
  63 #define M41T80_WATCHDOG_RB1     BIT(1)  /* RB: Watchdog resolution */
  64 #define M41T80_WATCHDOG_RB0     BIT(0)  /* RB: Watchdog resolution */
  65
  66 #define M41T80_FEATURE_HT       BIT(0)  /* Halt feature */
  67 #define M41T80_FEATURE_BL       BIT(1)  /* Battery low indicator */
  68 #define M41T80_FEATURE_SQ       BIT(2)  /* Squarewave feature */
  69 #define M41T80_FEATURE_WD       BIT(3)  /* Extra watchdog resolution */
  70 #define M41T80_FEATURE_SQ_ALT   BIT(4)  /* RSx bits are in reg 4 */
  71
  72 static DEFINE_MUTEX(m41t80_rtc_mutex);
  73 static const struct i2c_device_id m41t80_id[] = {
  74         { "m41t62", M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT },
  75         { "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
  76         { "m41t80", M41T80_FEATURE_SQ },
  77         { "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
  78         { "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  79         { "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  80         { "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  81         { "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  82         { "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  83         { "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  84         { "rv4162", M41T80_FEATURE_SQ | M41T80_FEATURE_WD | M41T80_FEATURE_SQ_ALT },
  85         { }
  86 };
  87 MODULE_DEVICE_TABLE(i2c, m41t80_id);
  88
  89 struct m41t80_data {
  90         u8 features;
  91         struct rtc_device *rtc;
  92 };
  93
  94 static irqreturn_t m41t80_handle_irq(int irq, void *dev_id)
  95 {
  96         struct i2c_client *client = dev_id;
  97         struct m41t80_data *m41t80 = i2c_get_clientdata(client);
  98         struct mutex *lock = &m41t80->rtc->ops_lock;
  99         unsigned long events = 0;
 100         int flags, flags_afe;
 101
 102         mutex_lock(lock);
 103
 104         flags_afe = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 105         if (flags_afe < 0) {
 106                 mutex_unlock(lock);
 107                 return IRQ_NONE;
 108         }
 109
 110         flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 111         if (flags <= 0) {
 112                 mutex_unlock(lock);
 113                 return IRQ_NONE;
 114         }
 115
 116         if (flags & M41T80_FLAGS_AF) {
 117                 flags &= ~M41T80_FLAGS_AF;
 118                 flags_afe &= ~M41T80_ALMON_AFE;
 119                 events |= RTC_AF;
 120         }
 121
 122         if (events) {
 123                 rtc_update_irq(m41t80->rtc, 1, events);
 124                 i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS, flags);
 125                 i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 126                                           flags_afe);
 127         }
 128
 129         mutex_unlock(lock);
 130
 131         return IRQ_HANDLED;
 132 }
 133
 134 static int m41t80_get_datetime(struct i2c_client *client,
 135                                struct rtc_time *tm)
 136 {
 137         unsigned char buf[8];
 138         int err, flags;
 139
 140         flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 141         if (flags < 0)
 142                 return flags;
 143
 144         if (flags & M41T80_FLAGS_OF) {
 145                 dev_err(&client->dev, "Oscillator failure, data is invalid.\n");
 146                 return -EINVAL;
 147         }
 148
 149         err = i2c_smbus_read_i2c_block_data(client, M41T80_REG_SSEC,
 150                                             sizeof(buf), buf);
 151         if (err < 0) {
 152                 dev_err(&client->dev, "Unable to read date\n");
 153                 return -EIO;
 154         }
 155
 156         tm->tm_sec = bcd2bin(buf[M41T80_REG_SEC] & 0x7f);
 157         tm->tm_min = bcd2bin(buf[M41T80_REG_MIN] & 0x7f);
 158         tm->tm_hour = bcd2bin(buf[M41T80_REG_HOUR] & 0x3f);
 159         tm->tm_mday = bcd2bin(buf[M41T80_REG_DAY] & 0x3f);
 160         tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
 161         tm->tm_mon = bcd2bin(buf[M41T80_REG_MON] & 0x1f) - 1;
 162
 163         /* assume 20YY not 19YY, and ignore the Century Bit */
 164         tm->tm_year = bcd2bin(buf[M41T80_REG_YEAR]) + 100;
 165         return rtc_valid_tm(tm);
 166 }
 167
 168 /* Sets the given date and time to the real time clock. */
 169 static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 170 {
 171         unsigned char buf[8];
 172         int err, flags;
 173
 174         if (tm->tm_year < 100 || tm->tm_year > 199)
 175                 return -EINVAL;
 176
 177         buf[M41T80_REG_SSEC] = 0;
 178         buf[M41T80_REG_SEC] = bin2bcd(tm->tm_sec);
 179         buf[M41T80_REG_MIN] = bin2bcd(tm->tm_min);
 180         buf[M41T80_REG_HOUR] = bin2bcd(tm->tm_hour);
 181         buf[M41T80_REG_DAY] = bin2bcd(tm->tm_mday);
 182         buf[M41T80_REG_MON] = bin2bcd(tm->tm_mon + 1);
 183         buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year - 100);
 184         buf[M41T80_REG_WDAY] = tm->tm_wday;
 185
 186         err = i2c_smbus_write_i2c_block_data(client, M41T80_REG_SSEC,
 187                                              sizeof(buf), buf);
 188         if (err < 0) {
 189                 dev_err(&client->dev, "Unable to write to date registers\n");
 190                 return err;
 191         }
 192
 193         /* Clear the OF bit of Flags Register */
 194         flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 195         if (flags < 0)
 196                 return flags;
 197
 198         if (i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS,
 199                                       flags & ~M41T80_FLAGS_OF)) {
 200                 dev_err(&client->dev, "Unable to write flags register\n");
 201                 return -EIO;
 202         }
 203
 204         return err;
 205 }
 206
 207 static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
 208 {
 209         struct i2c_client *client = to_i2c_client(dev);
 210         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 211         u8 reg;
 212
 213         if (clientdata->features & M41T80_FEATURE_BL) {
 214                 reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 215                 seq_printf(seq, "battery\t\t: %s\n",
 216                            (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
 217         }
 218         return 0;
 219 }
 220
 221 static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
 222 {
 223         return m41t80_get_datetime(to_i2c_client(dev), tm);
 224 }
 225
 226 static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
 227 {
 228         return m41t80_set_datetime(to_i2c_client(dev), tm);
 229 }
 230
 231 static int m41t80_alarm_irq_enable(struct device *dev, unsigned int enabled)
 232 {
 233         struct i2c_client *client = to_i2c_client(dev);
 234         int flags, retval;
 235
 236         flags = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 237         if (flags < 0)
 238                 return flags;
 239
 240         if (enabled)
 241                 flags |= M41T80_ALMON_AFE;
 242         else
 243                 flags &= ~M41T80_ALMON_AFE;
 244
 245         retval = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, flags);
 246         if (retval < 0) {
 247                 dev_err(dev, "Unable to enable alarm IRQ %d\n", retval);
 248                 return retval;
 249         }
 250         return 0;
 251 }
 252
 253 static int m41t80_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 254 {
 255         struct i2c_client *client = to_i2c_client(dev);
 256         u8 alarmvals[5];
 257         int ret, err;
 258
 259         alarmvals[0] = bin2bcd(alrm->time.tm_mon + 1);
 260         alarmvals[1] = bin2bcd(alrm->time.tm_mday);
 261         alarmvals[2] = bin2bcd(alrm->time.tm_hour);
 262         alarmvals[3] = bin2bcd(alrm->time.tm_min);
 263         alarmvals[4] = bin2bcd(alrm->time.tm_sec);
 264
 265         /* Clear AF and AFE flags */
 266         ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 267         if (ret < 0)
 268                 return ret;
 269         err = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 270                                         ret & ~(M41T80_ALMON_AFE));
 271         if (err < 0) {
 272                 dev_err(dev, "Unable to clear AFE bit\n");
 273                 return err;
 274         }
 275
 276         ret = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 277         if (ret < 0)
 278                 return ret;
 279
 280         err = i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS,
 281                                         ret & ~(M41T80_FLAGS_AF));
 282         if (err < 0) {
 283                 dev_err(dev, "Unable to clear AF bit\n");
 284                 return err;
 285         }
 286
 287         /* Write the alarm */
 288         err = i2c_smbus_write_i2c_block_data(client, M41T80_REG_ALARM_MON,
 289                                              5, alarmvals);
 290         if (err)
 291                 return err;
 292
 293         /* Enable the alarm interrupt */
 294         if (alrm->enabled) {
 295                 alarmvals[0] |= M41T80_ALMON_AFE;
 296                 err = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 297                                                 alarmvals[0]);
 298                 if (err)
 299                         return err;
 300         }
 301
 302         return 0;
 303 }
 304
 305 static int m41t80_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 306 {
 307         struct i2c_client *client = to_i2c_client(dev);
 308         u8 alarmvals[5];
 309         int flags, ret;
 310
 311         ret = i2c_smbus_read_i2c_block_data(client, M41T80_REG_ALARM_MON,
 312                                             5, alarmvals);
 313         if (ret != 5)
 314                 return ret < 0 ? ret : -EIO;
 315
 316         flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 317         if (flags < 0)
 318                 return flags;
 319
 320         alrm->time.tm_sec  = bcd2bin(alarmvals[4] & 0x7f);
 321         alrm->time.tm_min  = bcd2bin(alarmvals[3] & 0x7f);
 322         alrm->time.tm_hour = bcd2bin(alarmvals[2] & 0x3f);
 323         alrm->time.tm_mday = bcd2bin(alarmvals[1] & 0x3f);
 324         alrm->time.tm_mon  = bcd2bin(alarmvals[0] & 0x3f);
 325
 326         alrm->enabled = !!(alarmvals[0] & M41T80_ALMON_AFE);
 327         alrm->pending = (flags & M41T80_FLAGS_AF) && alrm->enabled;
 328
 329         return 0;
 330 }
 331
 332 static struct rtc_class_ops m41t80_rtc_ops = {
 333         .read_time = m41t80_rtc_read_time,
 334         .set_time = m41t80_rtc_set_time,
 335         .proc = m41t80_rtc_proc,
 336 };
 337
 338 #ifdef CONFIG_PM_SLEEP
 339 static int m41t80_suspend(struct device *dev)
 340 {
 341         struct i2c_client *client = to_i2c_client(dev);
 342
 343         if (client->irq >= 0 && device_may_wakeup(dev))
 344                 enable_irq_wake(client->irq);
 345
 346         return 0;
 347 }
 348
 349 static int m41t80_resume(struct device *dev)
 350 {
 351         struct i2c_client *client = to_i2c_client(dev);
 352
 353         if (client->irq >= 0 && device_may_wakeup(dev))
 354                 disable_irq_wake(client->irq);
 355
 356         return 0;
 357 }
 358 #endif
 359
 360 static SIMPLE_DEV_PM_OPS(m41t80_pm, m41t80_suspend, m41t80_resume);
 361
 362 static ssize_t flags_show(struct device *dev,
 363                           struct device_attribute *attr, char *buf)
 364 {
 365         struct i2c_client *client = to_i2c_client(dev);
 366         int val;
 367
 368         val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 369         if (val < 0)
 370                 return val;
 371         return sprintf(buf, "%#x\n", val);
 372 }
 373 static DEVICE_ATTR_RO(flags);
 374
 375 static ssize_t sqwfreq_show(struct device *dev,
 376                             struct device_attribute *attr, char *buf)
 377 {
 378         struct i2c_client *client = to_i2c_client(dev);
 379         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 380         int val, reg_sqw;
 381
 382         if (!(clientdata->features & M41T80_FEATURE_SQ))
 383                 return -EINVAL;
 384
 385         reg_sqw = M41T80_REG_SQW;
 386         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 387                 reg_sqw = M41T80_REG_WDAY;
 388         val = i2c_smbus_read_byte_data(client, reg_sqw);
 389         if (val < 0)
 390                 return val;
 391         val = (val >> 4) & 0xf;
 392         switch (val) {
 393         case 0:
 394                 break;
 395         case 1:
 396                 val = 32768;
 397                 break;
 398         default:
 399                 val = 32768 >> val;
 400         }
 401         return sprintf(buf, "%d\n", val);
 402 }
 403
 404 static ssize_t sqwfreq_store(struct device *dev,
 405                              struct device_attribute *attr,
 406                              const char *buf, size_t count)
 407 {
 408         struct i2c_client *client = to_i2c_client(dev);
 409         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 410         int almon, sqw, reg_sqw, rc;
 411         unsigned long val;
 412
 413         rc = kstrtoul(buf, 0, &val);
 414         if (rc < 0)
 415                 return rc;
 416
 417         if (!(clientdata->features & M41T80_FEATURE_SQ))
 418                 return -EINVAL;
 419
 420         if (val) {
 421                 if (!is_power_of_2(val))
 422                         return -EINVAL;
 423                 val = ilog2(val);
 424                 if (val == 15)
 425                         val = 1;
 426                 else if (val < 14)
 427                         val = 15 - val;
 428                 else
 429                         return -EINVAL;
 430         }
 431         /* disable SQW, set SQW frequency & re-enable */
 432         almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 433         if (almon < 0)
 434                 return almon;
 435         reg_sqw = M41T80_REG_SQW;
 436         if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 437                 reg_sqw = M41T80_REG_WDAY;
 438         sqw = i2c_smbus_read_byte_data(client, reg_sqw);
 439         if (sqw < 0)
 440                 return sqw;
 441         sqw = (sqw & 0x0f) | (val << 4);
 442
 443         rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 444                                        almon & ~M41T80_ALMON_SQWE);
 445         if (rc < 0)
 446                 return rc;
 447
 448         if (val) {
 449                 rc = i2c_smbus_write_byte_data(client, reg_sqw, sqw);
 450                 if (rc < 0)
 451                         return rc;
 452
 453                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 454                                                almon | M41T80_ALMON_SQWE);
 455                 if (rc < 0)
 456                         return rc;
 457         }
 458         return count;
 459 }
 460 static DEVICE_ATTR_RW(sqwfreq);
 461
 462 static struct attribute *attrs[] = {
 463         &dev_attr_flags.attr,
 464         &dev_attr_sqwfreq.attr,
 465         NULL,
 466 };
 467
 468 static struct attribute_group attr_group = {
 469         .attrs = attrs,
 470 };
 471
 472 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 473 /*
 474  *****************************************************************************
 475  *
 476  * Watchdog Driver
 477  *
 478  *****************************************************************************
 479  */
 480 static struct i2c_client *save_client;
 481
 482 /* Default margin */
 483 #define WD_TIMO 60              /* 1..31 seconds */
 484
 485 static int wdt_margin = WD_TIMO;
 486 module_param(wdt_margin, int, 0);
 487 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 488
 489 static unsigned long wdt_is_open;
 490 static int boot_flag;
 491
 492 /**
 493  *      wdt_ping:
 494  *
 495  *      Reload counter one with the watchdog timeout. We don't bother reloading
 496  *      the cascade counter.
 497  */
 498 static void wdt_ping(void)
 499 {
 500         unsigned char i2c_data[2];
 501         struct i2c_msg msgs1[1] = {
 502                 {
 503                         .addr   = save_client->addr,
 504                         .flags  = 0,
 505                         .len    = 2,
 506                         .buf    = i2c_data,
 507                 },
 508         };
 509         struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 510
 511         i2c_data[0] = 0x09;             /* watchdog register */
 512
 513         if (wdt_margin > 31)
 514                 i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 515         else
 516                 /*
 517                  * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 518                  */
 519                 i2c_data[1] = wdt_margin << 2 | 0x82;
 520
 521         /*
 522          * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 523          * that would be an invalid resolution.
 524          */
 525         if (clientdata->features & M41T80_FEATURE_WD)
 526                 i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 527
 528         i2c_transfer(save_client->adapter, msgs1, 1);
 529 }
 530
 531 /**
 532  *      wdt_disable:
 533  *
 534  *      disables watchdog.
 535  */
 536 static void wdt_disable(void)
 537 {
 538         unsigned char i2c_data[2], i2c_buf[0x10];
 539         struct i2c_msg msgs0[2] = {
 540                 {
 541                         .addr   = save_client->addr,
 542                         .flags  = 0,
 543                         .len    = 1,
 544                         .buf    = i2c_data,
 545                 },
 546                 {
 547                         .addr   = save_client->addr,
 548                         .flags  = I2C_M_RD,
 549                         .len    = 1,
 550                         .buf    = i2c_buf,
 551                 },
 552         };
 553         struct i2c_msg msgs1[1] = {
 554                 {
 555                         .addr   = save_client->addr,
 556                         .flags  = 0,
 557                         .len    = 2,
 558                         .buf    = i2c_data,
 559                 },
 560         };
 561
 562         i2c_data[0] = 0x09;
 563         i2c_transfer(save_client->adapter, msgs0, 2);
 564
 565         i2c_data[0] = 0x09;
 566         i2c_data[1] = 0x00;
 567         i2c_transfer(save_client->adapter, msgs1, 1);
 568 }
 569
 570 /**
 571  *      wdt_write:
 572  *      @file: file handle to the watchdog
 573  *      @buf: buffer to write (unused as data does not matter here
 574  *      @count: count of bytes
 575  *      @ppos: pointer to the position to write. No seeks allowed
 576  *
 577  *      A write to a watchdog device is defined as a keepalive signal. Any
 578  *      write of data will do, as we we don't define content meaning.
 579  */
 580 static ssize_t wdt_write(struct file *file, const char __user *buf,
 581                          size_t count, loff_t *ppos)
 582 {
 583         if (count) {
 584                 wdt_ping();
 585                 return 1;
 586         }
 587         return 0;
 588 }
 589
 590 static ssize_t wdt_read(struct file *file, char __user *buf,
 591                         size_t count, loff_t *ppos)
 592 {
 593         return 0;
 594 }
 595
 596 /**
 597  *      wdt_ioctl:
 598  *      @inode: inode of the device
 599  *      @file: file handle to the device
 600  *      @cmd: watchdog command
 601  *      @arg: argument pointer
 602  *
 603  *      The watchdog API defines a common set of functions for all watchdogs
 604  *      according to their available features. We only actually usefully support
 605  *      querying capabilities and current status.
 606  */
 607 static int wdt_ioctl(struct file *file, unsigned int cmd,
 608                      unsigned long arg)
 609 {
 610         int new_margin, rv;
 611         static struct watchdog_info ident = {
 612                 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 613                         WDIOF_SETTIMEOUT,
 614                 .firmware_version = 1,
 615                 .identity = "M41T80 WTD"
 616         };
 617
 618         switch (cmd) {
 619         case WDIOC_GETSUPPORT:
 620                 return copy_to_user((struct watchdog_info __user *)arg, &ident,
 621                                     sizeof(ident)) ? -EFAULT : 0;
 622
 623         case WDIOC_GETSTATUS:
 624         case WDIOC_GETBOOTSTATUS:
 625                 return put_user(boot_flag, (int __user *)arg);
 626         case WDIOC_KEEPALIVE:
 627                 wdt_ping();
 628                 return 0;
 629         case WDIOC_SETTIMEOUT:
 630                 if (get_user(new_margin, (int __user *)arg))
 631                         return -EFAULT;
 632                 /* Arbitrary, can't find the card's limits */
 633                 if (new_margin < 1 || new_margin > 124)
 634                         return -EINVAL;
 635                 wdt_margin = new_margin;
 636                 wdt_ping();
 637                 /* Fall */
 638         case WDIOC_GETTIMEOUT:
 639                 return put_user(wdt_margin, (int __user *)arg);
 640
 641         case WDIOC_SETOPTIONS:
 642                 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 643                         return -EFAULT;
 644
 645                 if (rv & WDIOS_DISABLECARD) {
 646                         pr_info("disable watchdog\n");
 647                         wdt_disable();
 648                 }
 649
 650                 if (rv & WDIOS_ENABLECARD) {
 651                         pr_info("enable watchdog\n");
 652                         wdt_ping();
 653                 }
 654
 655                 return -EINVAL;
 656         }
 657         return -ENOTTY;
 658 }
 659
 660 static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 661                                unsigned long arg)
 662 {
 663         int ret;
 664
 665         mutex_lock(&m41t80_rtc_mutex);
 666         ret = wdt_ioctl(file, cmd, arg);
 667         mutex_unlock(&m41t80_rtc_mutex);
 668
 669         return ret;
 670 }
 671
 672 /**
 673  *      wdt_open:
 674  *      @inode: inode of device
 675  *      @file: file handle to device
 676  *
 677  */
 678 static int wdt_open(struct inode *inode, struct file *file)
 679 {
 680         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 681                 mutex_lock(&m41t80_rtc_mutex);
 682                 if (test_and_set_bit(0, &wdt_is_open)) {
 683                         mutex_unlock(&m41t80_rtc_mutex);
 684                         return -EBUSY;
 685                 }
 686                 /*
 687                  *      Activate
 688                  */
 689                 wdt_is_open = 1;
 690                 mutex_unlock(&m41t80_rtc_mutex);
 691                 return nonseekable_open(inode, file);
 692         }
 693         return -ENODEV;
 694 }
 695
 696 /**
 697  *      wdt_close:
 698  *      @inode: inode to board
 699  *      @file: file handle to board
 700  *
 701  */
 702 static int wdt_release(struct inode *inode, struct file *file)
 703 {
 704         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 705                 clear_bit(0, &wdt_is_open);
 706         return 0;
 707 }
 708
 709 /**
 710  *      notify_sys:
 711  *      @this: our notifier block
 712  *      @code: the event being reported
 713  *      @unused: unused
 714  *
 715  *      Our notifier is called on system shutdowns. We want to turn the card
 716  *      off at reboot otherwise the machine will reboot again during memory
 717  *      test or worse yet during the following fsck. This would suck, in fact
 718  *      trust me - if it happens it does suck.
 719  */
 720 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 721                           void *unused)
 722 {
 723         if (code == SYS_DOWN || code == SYS_HALT)
 724                 /* Disable Watchdog */
 725                 wdt_disable();
 726         return NOTIFY_DONE;
 727 }
 728
 729 static const struct file_operations wdt_fops = {
 730         .owner  = THIS_MODULE,
 731         .read   = wdt_read,
 732         .unlocked_ioctl = wdt_unlocked_ioctl,
 733         .write  = wdt_write,
 734         .open   = wdt_open,
 735         .release = wdt_release,
 736         .llseek = no_llseek,
 737 };
 738
 739 static struct miscdevice wdt_dev = {
 740         .minor = WATCHDOG_MINOR,
 741         .name = "watchdog",
 742         .fops = &wdt_fops,
 743 };
 744
 745 /*
 746  *      The WDT card needs to learn about soft shutdowns in order to
 747  *      turn the timebomb registers off.
 748  */
 749 static struct notifier_block wdt_notifier = {
 750         .notifier_call = wdt_notify_sys,
 751 };
 752 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
 753
 754 /*
 755  *****************************************************************************
 756  *
 757  *      Driver Interface
 758  *
 759  *****************************************************************************
 760  */
 761
 762 static void m41t80_remove_sysfs_group(void *_dev)
 763 {
 764         struct device *dev = _dev;
 765
 766         sysfs_remove_group(&dev->kobj, &attr_group);
 767 }
 768
 769 static int m41t80_probe(struct i2c_client *client,
 770                         const struct i2c_device_id *id)
 771 {
 772         struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
 773         int rc = 0;
 774         struct rtc_device *rtc = NULL;
 775         struct rtc_time tm;
 776         struct m41t80_data *m41t80_data = NULL;
 777
 778         if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_I2C_BLOCK |
 779                                      I2C_FUNC_SMBUS_BYTE_DATA)) {
 780                 dev_err(&adapter->dev, "doesn't support I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK\n");
 781                 return -ENODEV;
 782         }
 783
 784         m41t80_data = devm_kzalloc(&client->dev, sizeof(*m41t80_data),
 785                                    GFP_KERNEL);
 786         if (!m41t80_data)
 787                 return -ENOMEM;
 788
 789         m41t80_data->features = id->driver_data;
 790         i2c_set_clientdata(client, m41t80_data);
 791
 792         if (client->irq > 0) {
 793                 rc = devm_request_threaded_irq(&client->dev, client->irq,
 794                                                NULL, m41t80_handle_irq,
 795                                                IRQF_TRIGGER_LOW | IRQF_ONESHOT,
 796                                                "m41t80", client);
 797                 if (rc) {
 798                         dev_warn(&client->dev, "unable to request IRQ, alarms disabled\n");
 799                         client->irq = 0;
 800                 } else {
 801                         m41t80_rtc_ops.read_alarm = m41t80_read_alarm;
 802                         m41t80_rtc_ops.set_alarm = m41t80_set_alarm;
 803                         m41t80_rtc_ops.alarm_irq_enable = m41t80_alarm_irq_enable;
 804                         /* Enable the wakealarm */
 805                         device_init_wakeup(&client->dev, true);
 806                 }
 807         }
 808
 809         rtc = devm_rtc_device_register(&client->dev, client->name,
 810                                        &m41t80_rtc_ops, THIS_MODULE);
 811         if (IS_ERR(rtc))
 812                 return PTR_ERR(rtc);
 813
 814         m41t80_data->rtc = rtc;
 815
 816         /* Make sure HT (Halt Update) bit is cleared */
 817         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 818
 819         if (rc >= 0 && rc & M41T80_ALHOUR_HT) {
 820                 if (m41t80_data->features & M41T80_FEATURE_HT) {
 821                         m41t80_get_datetime(client, &tm);
 822                         dev_info(&client->dev, "HT bit was set!\n");
 823                         dev_info(&client->dev,
 824                                  "Power Down at %04i-%02i-%02i %02i:%02i:%02i\n",
 825                                  tm.tm_year + 1900,
 826                                  tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
 827                                  tm.tm_min, tm.tm_sec);
 828                 }
 829                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_HOUR,
 830                                                rc & ~M41T80_ALHOUR_HT);
 831         }
 832
 833         if (rc < 0) {
 834                 dev_err(&client->dev, "Can't clear HT bit\n");
 835                 return rc;
 836         }
 837
 838         /* Make sure ST (stop) bit is cleared */
 839         rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 840
 841         if (rc >= 0 && rc & M41T80_SEC_ST)
 842                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 843                                                rc & ~M41T80_SEC_ST);
 844         if (rc < 0) {
 845                 dev_err(&client->dev, "Can't clear ST bit\n");
 846                 return rc;
 847         }
 848
 849         /* Export sysfs entries */
 850         rc = sysfs_create_group(&(&client->dev)->kobj, &attr_group);
 851         if (rc) {
 852                 dev_err(&client->dev, "Failed to create sysfs group: %d\n", rc);
 853                 return rc;
 854         }
 855
 856         rc = devm_add_action_or_reset(&client->dev, m41t80_remove_sysfs_group,
 857                                       &client->dev);
 858         if (rc) {
 859                 dev_err(&client->dev,
 860                         "Failed to add sysfs cleanup action: %d\n", rc);
 861                 return rc;
 862         }
 863
 864 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 865         if (m41t80_data->features & M41T80_FEATURE_HT) {
 866                 save_client = client;
 867                 rc = misc_register(&wdt_dev);
 868                 if (rc)
 869                         return rc;
 870                 rc = register_reboot_notifier(&wdt_notifier);
 871                 if (rc) {
 872                         misc_deregister(&wdt_dev);
 873                         return rc;
 874                 }
 875         }
 876 #endif
 877         return 0;
 878 }
 879
 880 static int m41t80_remove(struct i2c_client *client)
 881 {
 882 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 883         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 884
 885         if (clientdata->features & M41T80_FEATURE_HT) {
 886                 misc_deregister(&wdt_dev);
 887                 unregister_reboot_notifier(&wdt_notifier);
 888         }
 889 #endif
 890
 891         return 0;
 892 }
 893
 894 static struct i2c_driver m41t80_driver = {
 895         .driver = {
 896                 .name = "rtc-m41t80",
 897                 .pm = &m41t80_pm,
 898         },
 899         .probe = m41t80_probe,
 900         .remove = m41t80_remove,
 901         .id_table = m41t80_id,
 902 };
 903
 904 module_i2c_driver(m41t80_driver);
 905
 906 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
 907 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
 908 MODULE_LICENSE("GPL");