linux/drivers/rtc/rtc-m41t80.c
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   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
  71static DEFINE_MUTEX(m41t80_rtc_mutex);
  72static 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};
  85MODULE_DEVICE_TABLE(i2c, m41t80_id);
  86
  87struct m41t80_data {
  88        u8 features;
  89        struct rtc_device *rtc;
  90};
  91
  92static 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. */
 129static 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)
 189static 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
 206static 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
 211static 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/*
 217 * XXX - m41t80 alarm functionality is reported broken.
 218 * until it is fixed, don't register alarm functions.
 219 */
 220static struct rtc_class_ops m41t80_rtc_ops = {
 221        .read_time = m41t80_rtc_read_time,
 222        .set_time = m41t80_rtc_set_time,
 223        .proc = m41t80_rtc_proc,
 224};
 225
 226#if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
 227static ssize_t m41t80_sysfs_show_flags(struct device *dev,
 228                                struct device_attribute *attr, char *buf)
 229{
 230        struct i2c_client *client = to_i2c_client(dev);
 231        int val;
 232
 233        val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 234        if (val < 0)
 235                return -EIO;
 236        return sprintf(buf, "%#x\n", val);
 237}
 238static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
 239
 240static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
 241                                struct device_attribute *attr, char *buf)
 242{
 243        struct i2c_client *client = to_i2c_client(dev);
 244        struct m41t80_data *clientdata = i2c_get_clientdata(client);
 245        int val, reg_sqw;
 246
 247        if (!(clientdata->features & M41T80_FEATURE_SQ))
 248                return -EINVAL;
 249
 250        reg_sqw = M41T80_REG_SQW;
 251        if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 252                reg_sqw = M41T80_REG_WDAY;
 253        val = i2c_smbus_read_byte_data(client, reg_sqw);
 254        if (val < 0)
 255                return -EIO;
 256        val = (val >> 4) & 0xf;
 257        switch (val) {
 258        case 0:
 259                break;
 260        case 1:
 261                val = 32768;
 262                break;
 263        default:
 264                val = 32768 >> val;
 265        }
 266        return sprintf(buf, "%d\n", val);
 267}
 268static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
 269                                struct device_attribute *attr,
 270                                const char *buf, size_t count)
 271{
 272        struct i2c_client *client = to_i2c_client(dev);
 273        struct m41t80_data *clientdata = i2c_get_clientdata(client);
 274        int almon, sqw, reg_sqw;
 275        int val = simple_strtoul(buf, NULL, 0);
 276
 277        if (!(clientdata->features & M41T80_FEATURE_SQ))
 278                return -EINVAL;
 279
 280        if (val) {
 281                if (!is_power_of_2(val))
 282                        return -EINVAL;
 283                val = ilog2(val);
 284                if (val == 15)
 285                        val = 1;
 286                else if (val < 14)
 287                        val = 15 - val;
 288                else
 289                        return -EINVAL;
 290        }
 291        /* disable SQW, set SQW frequency & re-enable */
 292        almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 293        if (almon < 0)
 294                return -EIO;
 295        reg_sqw = M41T80_REG_SQW;
 296        if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 297                reg_sqw = M41T80_REG_WDAY;
 298        sqw = i2c_smbus_read_byte_data(client, reg_sqw);
 299        if (sqw < 0)
 300                return -EIO;
 301        sqw = (sqw & 0x0f) | (val << 4);
 302        if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 303                                      almon & ~M41T80_ALMON_SQWE) < 0 ||
 304            i2c_smbus_write_byte_data(client, reg_sqw, sqw) < 0)
 305                return -EIO;
 306        if (val && i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 307                                             almon | M41T80_ALMON_SQWE) < 0)
 308                return -EIO;
 309        return count;
 310}
 311static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
 312                   m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
 313
 314static struct attribute *attrs[] = {
 315        &dev_attr_flags.attr,
 316        &dev_attr_sqwfreq.attr,
 317        NULL,
 318};
 319static struct attribute_group attr_group = {
 320        .attrs = attrs,
 321};
 322
 323static int m41t80_sysfs_register(struct device *dev)
 324{
 325        return sysfs_create_group(&dev->kobj, &attr_group);
 326}
 327#else
 328static int m41t80_sysfs_register(struct device *dev)
 329{
 330        return 0;
 331}
 332#endif
 333
 334#ifdef CONFIG_RTC_DRV_M41T80_WDT
 335/*
 336 *****************************************************************************
 337 *
 338 * Watchdog Driver
 339 *
 340 *****************************************************************************
 341 */
 342static struct i2c_client *save_client;
 343
 344/* Default margin */
 345#define WD_TIMO 60              /* 1..31 seconds */
 346
 347static int wdt_margin = WD_TIMO;
 348module_param(wdt_margin, int, 0);
 349MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 350
 351static unsigned long wdt_is_open;
 352static int boot_flag;
 353
 354/**
 355 *      wdt_ping:
 356 *
 357 *      Reload counter one with the watchdog timeout. We don't bother reloading
 358 *      the cascade counter.
 359 */
 360static void wdt_ping(void)
 361{
 362        unsigned char i2c_data[2];
 363        struct i2c_msg msgs1[1] = {
 364                {
 365                        .addr   = save_client->addr,
 366                        .flags  = 0,
 367                        .len    = 2,
 368                        .buf    = i2c_data,
 369                },
 370        };
 371        struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 372
 373        i2c_data[0] = 0x09;             /* watchdog register */
 374
 375        if (wdt_margin > 31)
 376                i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 377        else
 378                /*
 379                 * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 380                 */
 381                i2c_data[1] = wdt_margin<<2 | 0x82;
 382
 383        /*
 384         * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 385         * that would be an invalid resolution.
 386         */
 387        if (clientdata->features & M41T80_FEATURE_WD)
 388                i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 389
 390        i2c_transfer(save_client->adapter, msgs1, 1);
 391}
 392
 393/**
 394 *      wdt_disable:
 395 *
 396 *      disables watchdog.
 397 */
 398static void wdt_disable(void)
 399{
 400        unsigned char i2c_data[2], i2c_buf[0x10];
 401        struct i2c_msg msgs0[2] = {
 402                {
 403                        .addr   = save_client->addr,
 404                        .flags  = 0,
 405                        .len    = 1,
 406                        .buf    = i2c_data,
 407                },
 408                {
 409                        .addr   = save_client->addr,
 410                        .flags  = I2C_M_RD,
 411                        .len    = 1,
 412                        .buf    = i2c_buf,
 413                },
 414        };
 415        struct i2c_msg msgs1[1] = {
 416                {
 417                        .addr   = save_client->addr,
 418                        .flags  = 0,
 419                        .len    = 2,
 420                        .buf    = i2c_data,
 421                },
 422        };
 423
 424        i2c_data[0] = 0x09;
 425        i2c_transfer(save_client->adapter, msgs0, 2);
 426
 427        i2c_data[0] = 0x09;
 428        i2c_data[1] = 0x00;
 429        i2c_transfer(save_client->adapter, msgs1, 1);
 430}
 431
 432/**
 433 *      wdt_write:
 434 *      @file: file handle to the watchdog
 435 *      @buf: buffer to write (unused as data does not matter here
 436 *      @count: count of bytes
 437 *      @ppos: pointer to the position to write. No seeks allowed
 438 *
 439 *      A write to a watchdog device is defined as a keepalive signal. Any
 440 *      write of data will do, as we we don't define content meaning.
 441 */
 442static ssize_t wdt_write(struct file *file, const char __user *buf,
 443                         size_t count, loff_t *ppos)
 444{
 445        if (count) {
 446                wdt_ping();
 447                return 1;
 448        }
 449        return 0;
 450}
 451
 452static ssize_t wdt_read(struct file *file, char __user *buf,
 453                        size_t count, loff_t *ppos)
 454{
 455        return 0;
 456}
 457
 458/**
 459 *      wdt_ioctl:
 460 *      @inode: inode of the device
 461 *      @file: file handle to the device
 462 *      @cmd: watchdog command
 463 *      @arg: argument pointer
 464 *
 465 *      The watchdog API defines a common set of functions for all watchdogs
 466 *      according to their available features. We only actually usefully support
 467 *      querying capabilities and current status.
 468 */
 469static int wdt_ioctl(struct file *file, unsigned int cmd,
 470                     unsigned long arg)
 471{
 472        int new_margin, rv;
 473        static struct watchdog_info ident = {
 474                .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 475                        WDIOF_SETTIMEOUT,
 476                .firmware_version = 1,
 477                .identity = "M41T80 WTD"
 478        };
 479
 480        switch (cmd) {
 481        case WDIOC_GETSUPPORT:
 482                return copy_to_user((struct watchdog_info __user *)arg, &ident,
 483                                    sizeof(ident)) ? -EFAULT : 0;
 484
 485        case WDIOC_GETSTATUS:
 486        case WDIOC_GETBOOTSTATUS:
 487                return put_user(boot_flag, (int __user *)arg);
 488        case WDIOC_KEEPALIVE:
 489                wdt_ping();
 490                return 0;
 491        case WDIOC_SETTIMEOUT:
 492                if (get_user(new_margin, (int __user *)arg))
 493                        return -EFAULT;
 494                /* Arbitrary, can't find the card's limits */
 495                if (new_margin < 1 || new_margin > 124)
 496                        return -EINVAL;
 497                wdt_margin = new_margin;
 498                wdt_ping();
 499                /* Fall */
 500        case WDIOC_GETTIMEOUT:
 501                return put_user(wdt_margin, (int __user *)arg);
 502
 503        case WDIOC_SETOPTIONS:
 504                if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 505                        return -EFAULT;
 506
 507                if (rv & WDIOS_DISABLECARD) {
 508                        pr_info("rtc-m41t80: disable watchdog\n");
 509                        wdt_disable();
 510                }
 511
 512                if (rv & WDIOS_ENABLECARD) {
 513                        pr_info("rtc-m41t80: enable watchdog\n");
 514                        wdt_ping();
 515                }
 516
 517                return -EINVAL;
 518        }
 519        return -ENOTTY;
 520}
 521
 522static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 523                               unsigned long arg)
 524{
 525        int ret;
 526
 527        mutex_lock(&m41t80_rtc_mutex);
 528        ret = wdt_ioctl(file, cmd, arg);
 529        mutex_unlock(&m41t80_rtc_mutex);
 530
 531        return ret;
 532}
 533
 534/**
 535 *      wdt_open:
 536 *      @inode: inode of device
 537 *      @file: file handle to device
 538 *
 539 */
 540static int wdt_open(struct inode *inode, struct file *file)
 541{
 542        if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 543                mutex_lock(&m41t80_rtc_mutex);
 544                if (test_and_set_bit(0, &wdt_is_open)) {
 545                        mutex_unlock(&m41t80_rtc_mutex);
 546                        return -EBUSY;
 547                }
 548                /*
 549                 *      Activate
 550                 */
 551                wdt_is_open = 1;
 552                mutex_unlock(&m41t80_rtc_mutex);
 553                return nonseekable_open(inode, file);
 554        }
 555        return -ENODEV;
 556}
 557
 558/**
 559 *      wdt_close:
 560 *      @inode: inode to board
 561 *      @file: file handle to board
 562 *
 563 */
 564static int wdt_release(struct inode *inode, struct file *file)
 565{
 566        if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 567                clear_bit(0, &wdt_is_open);
 568        return 0;
 569}
 570
 571/**
 572 *      notify_sys:
 573 *      @this: our notifier block
 574 *      @code: the event being reported
 575 *      @unused: unused
 576 *
 577 *      Our notifier is called on system shutdowns. We want to turn the card
 578 *      off at reboot otherwise the machine will reboot again during memory
 579 *      test or worse yet during the following fsck. This would suck, in fact
 580 *      trust me - if it happens it does suck.
 581 */
 582static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 583                          void *unused)
 584{
 585        if (code == SYS_DOWN || code == SYS_HALT)
 586                /* Disable Watchdog */
 587                wdt_disable();
 588        return NOTIFY_DONE;
 589}
 590
 591static const struct file_operations wdt_fops = {
 592        .owner  = THIS_MODULE,
 593        .read   = wdt_read,
 594        .unlocked_ioctl = wdt_unlocked_ioctl,
 595        .write  = wdt_write,
 596        .open   = wdt_open,
 597        .release = wdt_release,
 598        .llseek = no_llseek,
 599};
 600
 601static struct miscdevice wdt_dev = {
 602        .minor = WATCHDOG_MINOR,
 603        .name = "watchdog",
 604        .fops = &wdt_fops,
 605};
 606
 607/*
 608 *      The WDT card needs to learn about soft shutdowns in order to
 609 *      turn the timebomb registers off.
 610 */
 611static struct notifier_block wdt_notifier = {
 612        .notifier_call = wdt_notify_sys,
 613};
 614#endif /* CONFIG_RTC_DRV_M41T80_WDT */
 615
 616/*
 617 *****************************************************************************
 618 *
 619 *      Driver Interface
 620 *
 621 *****************************************************************************
 622 */
 623static int m41t80_probe(struct i2c_client *client,
 624                        const struct i2c_device_id *id)
 625{
 626        int rc = 0;
 627        struct rtc_device *rtc = NULL;
 628        struct rtc_time tm;
 629        struct m41t80_data *clientdata = NULL;
 630
 631        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
 632                                     | I2C_FUNC_SMBUS_BYTE_DATA)) {
 633                rc = -ENODEV;
 634                goto exit;
 635        }
 636
 637        dev_info(&client->dev,
 638                 "chip found, driver version " DRV_VERSION "\n");
 639
 640        clientdata = devm_kzalloc(&client->dev, sizeof(*clientdata),
 641                                GFP_KERNEL);
 642        if (!clientdata) {
 643                rc = -ENOMEM;
 644                goto exit;
 645        }
 646
 647        clientdata->features = id->driver_data;
 648        i2c_set_clientdata(client, clientdata);
 649
 650        rtc = devm_rtc_device_register(&client->dev, client->name,
 651                                        &m41t80_rtc_ops, THIS_MODULE);
 652        if (IS_ERR(rtc)) {
 653                rc = PTR_ERR(rtc);
 654                rtc = NULL;
 655                goto exit;
 656        }
 657
 658        clientdata->rtc = rtc;
 659
 660        /* Make sure HT (Halt Update) bit is cleared */
 661        rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 662        if (rc < 0)
 663                goto ht_err;
 664
 665        if (rc & M41T80_ALHOUR_HT) {
 666                if (clientdata->features & M41T80_FEATURE_HT) {
 667                        m41t80_get_datetime(client, &tm);
 668                        dev_info(&client->dev, "HT bit was set!\n");
 669                        dev_info(&client->dev,
 670                                 "Power Down at "
 671                                 "%04i-%02i-%02i %02i:%02i:%02i\n",
 672                                 tm.tm_year + 1900,
 673                                 tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
 674                                 tm.tm_min, tm.tm_sec);
 675                }
 676                if (i2c_smbus_write_byte_data(client,
 677                                              M41T80_REG_ALARM_HOUR,
 678                                              rc & ~M41T80_ALHOUR_HT) < 0)
 679                        goto ht_err;
 680        }
 681
 682        /* Make sure ST (stop) bit is cleared */
 683        rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 684        if (rc < 0)
 685                goto st_err;
 686
 687        if (rc & M41T80_SEC_ST) {
 688                if (i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 689                                              rc & ~M41T80_SEC_ST) < 0)
 690                        goto st_err;
 691        }
 692
 693        rc = m41t80_sysfs_register(&client->dev);
 694        if (rc)
 695                goto exit;
 696
 697#ifdef CONFIG_RTC_DRV_M41T80_WDT
 698        if (clientdata->features & M41T80_FEATURE_HT) {
 699                save_client = client;
 700                rc = misc_register(&wdt_dev);
 701                if (rc)
 702                        goto exit;
 703                rc = register_reboot_notifier(&wdt_notifier);
 704                if (rc) {
 705                        misc_deregister(&wdt_dev);
 706                        goto exit;
 707                }
 708        }
 709#endif
 710        return 0;
 711
 712st_err:
 713        rc = -EIO;
 714        dev_err(&client->dev, "Can't clear ST bit\n");
 715        goto exit;
 716ht_err:
 717        rc = -EIO;
 718        dev_err(&client->dev, "Can't clear HT bit\n");
 719        goto exit;
 720
 721exit:
 722        return rc;
 723}
 724
 725static int m41t80_remove(struct i2c_client *client)
 726{
 727#ifdef CONFIG_RTC_DRV_M41T80_WDT
 728        struct m41t80_data *clientdata = i2c_get_clientdata(client);
 729
 730        if (clientdata->features & M41T80_FEATURE_HT) {
 731                misc_deregister(&wdt_dev);
 732                unregister_reboot_notifier(&wdt_notifier);
 733        }
 734#endif
 735
 736        return 0;
 737}
 738
 739static struct i2c_driver m41t80_driver = {
 740        .driver = {
 741                .name = "rtc-m41t80",
 742        },
 743        .probe = m41t80_probe,
 744        .remove = m41t80_remove,
 745        .id_table = m41t80_id,
 746};
 747
 748module_i2c_driver(m41t80_driver);
 749
 750MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
 751MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
 752MODULE_LICENSE("GPL");
 753MODULE_VERSION(DRV_VERSION);
 754
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