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
 216static int m41t80_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 217{
 218        struct i2c_client *client = to_i2c_client(dev);
 219        int rc;
 220
 221        rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 222        if (rc < 0)
 223                goto err;
 224
 225        if (enabled)
 226                rc |= M41T80_ALMON_AFE;
 227        else
 228                rc &= ~M41T80_ALMON_AFE;
 229
 230        if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, rc) < 0)
 231                goto err;
 232
 233        return 0;
 234err:
 235        return -EIO;
 236}
 237
 238static int m41t80_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 239{
 240        struct i2c_client *client = to_i2c_client(dev);
 241        u8 wbuf[1 + M41T80_ALARM_REG_SIZE];
 242        u8 *buf = &wbuf[1];
 243        u8 *reg = buf - M41T80_REG_ALARM_MON;
 244        u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
 245        struct i2c_msg msgs_in[] = {
 246                {
 247                        .addr   = client->addr,
 248                        .flags  = 0,
 249                        .len    = 1,
 250                        .buf    = dt_addr,
 251                },
 252                {
 253                        .addr   = client->addr,
 254                        .flags  = I2C_M_RD,
 255                        .len    = M41T80_ALARM_REG_SIZE,
 256                        .buf    = buf,
 257                },
 258        };
 259        struct i2c_msg msgs[] = {
 260                {
 261                        .addr   = client->addr,
 262                        .flags  = 0,
 263                        .len    = 1 + M41T80_ALARM_REG_SIZE,
 264                        .buf    = wbuf,
 265                 },
 266        };
 267
 268        if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
 269                dev_err(&client->dev, "read error\n");
 270                return -EIO;
 271        }
 272        reg[M41T80_REG_ALARM_MON] &= ~(0x1f | M41T80_ALMON_AFE);
 273        reg[M41T80_REG_ALARM_DAY] = 0;
 274        reg[M41T80_REG_ALARM_HOUR] &= ~(0x3f | 0x80);
 275        reg[M41T80_REG_ALARM_MIN] = 0;
 276        reg[M41T80_REG_ALARM_SEC] = 0;
 277
 278        wbuf[0] = M41T80_REG_ALARM_MON; /* offset into rtc's regs */
 279        reg[M41T80_REG_ALARM_SEC] |= t->time.tm_sec >= 0 ?
 280                bin2bcd(t->time.tm_sec) : 0x80;
 281        reg[M41T80_REG_ALARM_MIN] |= t->time.tm_min >= 0 ?
 282                bin2bcd(t->time.tm_min) : 0x80;
 283        reg[M41T80_REG_ALARM_HOUR] |= t->time.tm_hour >= 0 ?
 284                bin2bcd(t->time.tm_hour) : 0x80;
 285        reg[M41T80_REG_ALARM_DAY] |= t->time.tm_mday >= 0 ?
 286                bin2bcd(t->time.tm_mday) : 0x80;
 287        if (t->time.tm_mon >= 0)
 288                reg[M41T80_REG_ALARM_MON] |= bin2bcd(t->time.tm_mon + 1);
 289        else
 290                reg[M41T80_REG_ALARM_DAY] |= 0x40;
 291
 292        if (i2c_transfer(client->adapter, msgs, 1) != 1) {
 293                dev_err(&client->dev, "write error\n");
 294                return -EIO;
 295        }
 296
 297        if (t->enabled) {
 298                reg[M41T80_REG_ALARM_MON] |= M41T80_ALMON_AFE;
 299                if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 300                                              reg[M41T80_REG_ALARM_MON]) < 0) {
 301                        dev_err(&client->dev, "write error\n");
 302                        return -EIO;
 303                }
 304        }
 305        return 0;
 306}
 307
 308static int m41t80_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 309{
 310        struct i2c_client *client = to_i2c_client(dev);
 311        u8 buf[M41T80_ALARM_REG_SIZE + 1]; /* all alarm regs and flags */
 312        u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
 313        u8 *reg = buf - M41T80_REG_ALARM_MON;
 314        struct i2c_msg msgs[] = {
 315                {
 316                        .addr   = client->addr,
 317                        .flags  = 0,
 318                        .len    = 1,
 319                        .buf    = dt_addr,
 320                },
 321                {
 322                        .addr   = client->addr,
 323                        .flags  = I2C_M_RD,
 324                        .len    = M41T80_ALARM_REG_SIZE + 1,
 325                        .buf    = buf,
 326                },
 327        };
 328
 329        if (i2c_transfer(client->adapter, msgs, 2) < 0) {
 330                dev_err(&client->dev, "read error\n");
 331                return -EIO;
 332        }
 333        t->time.tm_sec = -1;
 334        t->time.tm_min = -1;
 335        t->time.tm_hour = -1;
 336        t->time.tm_mday = -1;
 337        t->time.tm_mon = -1;
 338        if (!(reg[M41T80_REG_ALARM_SEC] & 0x80))
 339                t->time.tm_sec = bcd2bin(reg[M41T80_REG_ALARM_SEC] & 0x7f);
 340        if (!(reg[M41T80_REG_ALARM_MIN] & 0x80))
 341                t->time.tm_min = bcd2bin(reg[M41T80_REG_ALARM_MIN] & 0x7f);
 342        if (!(reg[M41T80_REG_ALARM_HOUR] & 0x80))
 343                t->time.tm_hour = bcd2bin(reg[M41T80_REG_ALARM_HOUR] & 0x3f);
 344        if (!(reg[M41T80_REG_ALARM_DAY] & 0x80))
 345                t->time.tm_mday = bcd2bin(reg[M41T80_REG_ALARM_DAY] & 0x3f);
 346        if (!(reg[M41T80_REG_ALARM_DAY] & 0x40))
 347                t->time.tm_mon = bcd2bin(reg[M41T80_REG_ALARM_MON] & 0x1f) - 1;
 348        t->time.tm_year = -1;
 349        t->time.tm_wday = -1;
 350        t->time.tm_yday = -1;
 351        t->time.tm_isdst = -1;
 352        t->enabled = !!(reg[M41T80_REG_ALARM_MON] & M41T80_ALMON_AFE);
 353        t->pending = !!(reg[M41T80_REG_FLAGS] & M41T80_FLAGS_AF);
 354        return 0;
 355}
 356
 357static struct rtc_class_ops m41t80_rtc_ops = {
 358        .read_time = m41t80_rtc_read_time,
 359        .set_time = m41t80_rtc_set_time,
 360        /*
 361         * XXX - m41t80 alarm functionality is reported broken.
 362         * until it is fixed, don't register alarm functions.
 363         *
 364        .read_alarm = m41t80_rtc_read_alarm,
 365        .set_alarm = m41t80_rtc_set_alarm,
 366        */
 367        .proc = m41t80_rtc_proc,
 368        /*
 369         * See above comment on broken alarm
 370         *
 371        .alarm_irq_enable = m41t80_rtc_alarm_irq_enable,
 372        */
 373};
 374
 375#if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
 376static ssize_t m41t80_sysfs_show_flags(struct device *dev,
 377                                struct device_attribute *attr, char *buf)
 378{
 379        struct i2c_client *client = to_i2c_client(dev);
 380        int val;
 381
 382        val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 383        if (val < 0)
 384                return -EIO;
 385        return sprintf(buf, "%#x\n", val);
 386}
 387static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
 388
 389static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
 390                                struct device_attribute *attr, char *buf)
 391{
 392        struct i2c_client *client = to_i2c_client(dev);
 393        struct m41t80_data *clientdata = i2c_get_clientdata(client);
 394        int val, reg_sqw;
 395
 396        if (!(clientdata->features & M41T80_FEATURE_SQ))
 397                return -EINVAL;
 398
 399        reg_sqw = M41T80_REG_SQW;
 400        if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 401                reg_sqw = M41T80_REG_WDAY;
 402        val = i2c_smbus_read_byte_data(client, reg_sqw);
 403        if (val < 0)
 404                return -EIO;
 405        val = (val >> 4) & 0xf;
 406        switch (val) {
 407        case 0:
 408                break;
 409        case 1:
 410                val = 32768;
 411                break;
 412        default:
 413                val = 32768 >> val;
 414        }
 415        return sprintf(buf, "%d\n", val);
 416}
 417static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
 418                                struct device_attribute *attr,
 419                                const char *buf, size_t count)
 420{
 421        struct i2c_client *client = to_i2c_client(dev);
 422        struct m41t80_data *clientdata = i2c_get_clientdata(client);
 423        int almon, sqw, reg_sqw;
 424        int val = simple_strtoul(buf, NULL, 0);
 425
 426        if (!(clientdata->features & M41T80_FEATURE_SQ))
 427                return -EINVAL;
 428
 429        if (val) {
 430                if (!is_power_of_2(val))
 431                        return -EINVAL;
 432                val = ilog2(val);
 433                if (val == 15)
 434                        val = 1;
 435                else if (val < 14)
 436                        val = 15 - val;
 437                else
 438                        return -EINVAL;
 439        }
 440        /* disable SQW, set SQW frequency & re-enable */
 441        almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 442        if (almon < 0)
 443                return -EIO;
 444        reg_sqw = M41T80_REG_SQW;
 445        if (clientdata->features & M41T80_FEATURE_SQ_ALT)
 446                reg_sqw = M41T80_REG_WDAY;
 447        sqw = i2c_smbus_read_byte_data(client, reg_sqw);
 448        if (sqw < 0)
 449                return -EIO;
 450        sqw = (sqw & 0x0f) | (val << 4);
 451        if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 452                                      almon & ~M41T80_ALMON_SQWE) < 0 ||
 453            i2c_smbus_write_byte_data(client, reg_sqw, sqw) < 0)
 454                return -EIO;
 455        if (val && i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 456                                             almon | M41T80_ALMON_SQWE) < 0)
 457                return -EIO;
 458        return count;
 459}
 460static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
 461                   m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
 462
 463static struct attribute *attrs[] = {
 464        &dev_attr_flags.attr,
 465        &dev_attr_sqwfreq.attr,
 466        NULL,
 467};
 468static struct attribute_group attr_group = {
 469        .attrs = attrs,
 470};
 471
 472static int m41t80_sysfs_register(struct device *dev)
 473{
 474        return sysfs_create_group(&dev->kobj, &attr_group);
 475}
 476#else
 477static int m41t80_sysfs_register(struct device *dev)
 478{
 479        return 0;
 480}
 481#endif
 482
 483#ifdef CONFIG_RTC_DRV_M41T80_WDT
 484/*
 485 *****************************************************************************
 486 *
 487 * Watchdog Driver
 488 *
 489 *****************************************************************************
 490 */
 491static struct i2c_client *save_client;
 492
 493/* Default margin */
 494#define WD_TIMO 60              /* 1..31 seconds */
 495
 496static int wdt_margin = WD_TIMO;
 497module_param(wdt_margin, int, 0);
 498MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 499
 500static unsigned long wdt_is_open;
 501static int boot_flag;
 502
 503/**
 504 *      wdt_ping:
 505 *
 506 *      Reload counter one with the watchdog timeout. We don't bother reloading
 507 *      the cascade counter.
 508 */
 509static void wdt_ping(void)
 510{
 511        unsigned char i2c_data[2];
 512        struct i2c_msg msgs1[1] = {
 513                {
 514                        .addr   = save_client->addr,
 515                        .flags  = 0,
 516                        .len    = 2,
 517                        .buf    = i2c_data,
 518                },
 519        };
 520        struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 521
 522        i2c_data[0] = 0x09;             /* watchdog register */
 523
 524        if (wdt_margin > 31)
 525                i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 526        else
 527                /*
 528                 * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 529                 */
 530                i2c_data[1] = wdt_margin<<2 | 0x82;
 531
 532        /*
 533         * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 534         * that would be an invalid resolution.
 535         */
 536        if (clientdata->features & M41T80_FEATURE_WD)
 537                i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 538
 539        i2c_transfer(save_client->adapter, msgs1, 1);
 540}
 541
 542/**
 543 *      wdt_disable:
 544 *
 545 *      disables watchdog.
 546 */
 547static void wdt_disable(void)
 548{
 549        unsigned char i2c_data[2], i2c_buf[0x10];
 550        struct i2c_msg msgs0[2] = {
 551                {
 552                        .addr   = save_client->addr,
 553                        .flags  = 0,
 554                        .len    = 1,
 555                        .buf    = i2c_data,
 556                },
 557                {
 558                        .addr   = save_client->addr,
 559                        .flags  = I2C_M_RD,
 560                        .len    = 1,
 561                        .buf    = i2c_buf,
 562                },
 563        };
 564        struct i2c_msg msgs1[1] = {
 565                {
 566                        .addr   = save_client->addr,
 567                        .flags  = 0,
 568                        .len    = 2,
 569                        .buf    = i2c_data,
 570                },
 571        };
 572
 573        i2c_data[0] = 0x09;
 574        i2c_transfer(save_client->adapter, msgs0, 2);
 575
 576        i2c_data[0] = 0x09;
 577        i2c_data[1] = 0x00;
 578        i2c_transfer(save_client->adapter, msgs1, 1);
 579}
 580
 581/**
 582 *      wdt_write:
 583 *      @file: file handle to the watchdog
 584 *      @buf: buffer to write (unused as data does not matter here
 585 *      @count: count of bytes
 586 *      @ppos: pointer to the position to write. No seeks allowed
 587 *
 588 *      A write to a watchdog device is defined as a keepalive signal. Any
 589 *      write of data will do, as we we don't define content meaning.
 590 */
 591static ssize_t wdt_write(struct file *file, const char __user *buf,
 592                         size_t count, loff_t *ppos)
 593{
 594        if (count) {
 595                wdt_ping();
 596                return 1;
 597        }
 598        return 0;
 599}
 600
 601static ssize_t wdt_read(struct file *file, char __user *buf,
 602                        size_t count, loff_t *ppos)
 603{
 604        return 0;
 605}
 606
 607/**
 608 *      wdt_ioctl:
 609 *      @inode: inode of the device
 610 *      @file: file handle to the device
 611 *      @cmd: watchdog command
 612 *      @arg: argument pointer
 613 *
 614 *      The watchdog API defines a common set of functions for all watchdogs
 615 *      according to their available features. We only actually usefully support
 616 *      querying capabilities and current status.
 617 */
 618static int wdt_ioctl(struct file *file, unsigned int cmd,
 619                     unsigned long arg)
 620{
 621        int new_margin, rv;
 622        static struct watchdog_info ident = {
 623                .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 624                        WDIOF_SETTIMEOUT,
 625                .firmware_version = 1,
 626                .identity = "M41T80 WTD"
 627        };
 628
 629        switch (cmd) {
 630        case WDIOC_GETSUPPORT:
 631                return copy_to_user((struct watchdog_info __user *)arg, &ident,
 632                                    sizeof(ident)) ? -EFAULT : 0;
 633
 634        case WDIOC_GETSTATUS:
 635        case WDIOC_GETBOOTSTATUS:
 636                return put_user(boot_flag, (int __user *)arg);
 637        case WDIOC_KEEPALIVE:
 638                wdt_ping();
 639                return 0;
 640        case WDIOC_SETTIMEOUT:
 641                if (get_user(new_margin, (int __user *)arg))
 642                        return -EFAULT;
 643                /* Arbitrary, can't find the card's limits */
 644                if (new_margin < 1 || new_margin > 124)
 645                        return -EINVAL;
 646                wdt_margin = new_margin;
 647                wdt_ping();
 648                /* Fall */
 649        case WDIOC_GETTIMEOUT:
 650                return put_user(wdt_margin, (int __user *)arg);
 651
 652        case WDIOC_SETOPTIONS:
 653                if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 654                        return -EFAULT;
 655
 656                if (rv & WDIOS_DISABLECARD) {
 657                        pr_info("rtc-m41t80: disable watchdog\n");
 658                        wdt_disable();
 659                }
 660
 661                if (rv & WDIOS_ENABLECARD) {
 662                        pr_info("rtc-m41t80: enable watchdog\n");
 663                        wdt_ping();
 664                }
 665
 666                return -EINVAL;
 667        }
 668        return -ENOTTY;
 669}
 670
 671static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 672                               unsigned long arg)
 673{
 674        int ret;
 675
 676        mutex_lock(&m41t80_rtc_mutex);
 677        ret = wdt_ioctl(file, cmd, arg);
 678        mutex_unlock(&m41t80_rtc_mutex);
 679
 680        return ret;
 681}
 682
 683/**
 684 *      wdt_open:
 685 *      @inode: inode of device
 686 *      @file: file handle to device
 687 *
 688 */
 689static int wdt_open(struct inode *inode, struct file *file)
 690{
 691        if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 692                mutex_lock(&m41t80_rtc_mutex);
 693                if (test_and_set_bit(0, &wdt_is_open)) {
 694                        mutex_unlock(&m41t80_rtc_mutex);
 695                        return -EBUSY;
 696                }
 697                /*
 698                 *      Activate
 699                 */
 700                wdt_is_open = 1;
 701                mutex_unlock(&m41t80_rtc_mutex);
 702                return nonseekable_open(inode, file);
 703        }
 704        return -ENODEV;
 705}
 706
 707/**
 708 *      wdt_close:
 709 *      @inode: inode to board
 710 *      @file: file handle to board
 711 *
 712 */
 713static int wdt_release(struct inode *inode, struct file *file)
 714{
 715        if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 716                clear_bit(0, &wdt_is_open);
 717        return 0;
 718}
 719
 720/**
 721 *      notify_sys:
 722 *      @this: our notifier block
 723 *      @code: the event being reported
 724 *      @unused: unused
 725 *
 726 *      Our notifier is called on system shutdowns. We want to turn the card
 727 *      off at reboot otherwise the machine will reboot again during memory
 728 *      test or worse yet during the following fsck. This would suck, in fact
 729 *      trust me - if it happens it does suck.
 730 */
 731static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 732                          void *unused)
 733{
 734        if (code == SYS_DOWN || code == SYS_HALT)
 735                /* Disable Watchdog */
 736                wdt_disable();
 737        return NOTIFY_DONE;
 738}
 739
 740static const struct file_operations wdt_fops = {
 741        .owner  = THIS_MODULE,
 742        .read   = wdt_read,
 743        .unlocked_ioctl = wdt_unlocked_ioctl,
 744        .write  = wdt_write,
 745        .open   = wdt_open,
 746        .release = wdt_release,
 747        .llseek = no_llseek,
 748};
 749
 750static struct miscdevice wdt_dev = {
 751        .minor = WATCHDOG_MINOR,
 752        .name = "watchdog",
 753        .fops = &wdt_fops,
 754};
 755
 756/*
 757 *      The WDT card needs to learn about soft shutdowns in order to
 758 *      turn the timebomb registers off.
 759 */
 760static struct notifier_block wdt_notifier = {
 761        .notifier_call = wdt_notify_sys,
 762};
 763#endif /* CONFIG_RTC_DRV_M41T80_WDT */
 764
 765/*
 766 *****************************************************************************
 767 *
 768 *      Driver Interface
 769 *
 770 *****************************************************************************
 771 */
 772static int m41t80_probe(struct i2c_client *client,
 773                        const struct i2c_device_id *id)
 774{
 775        int rc = 0;
 776        struct rtc_device *rtc = NULL;
 777        struct rtc_time tm;
 778        struct m41t80_data *clientdata = NULL;
 779
 780        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
 781                                     | I2C_FUNC_SMBUS_BYTE_DATA)) {
 782                rc = -ENODEV;
 783                goto exit;
 784        }
 785
 786        dev_info(&client->dev,
 787                 "chip found, driver version " DRV_VERSION "\n");
 788
 789        clientdata = kzalloc(sizeof(*clientdata), GFP_KERNEL);
 790        if (!clientdata) {
 791                rc = -ENOMEM;
 792                goto exit;
 793        }
 794
 795        clientdata->features = id->driver_data;
 796        i2c_set_clientdata(client, clientdata);
 797
 798        rtc = rtc_device_register(client->name, &client->dev,
 799                                  &m41t80_rtc_ops, THIS_MODULE);
 800        if (IS_ERR(rtc)) {
 801                rc = PTR_ERR(rtc);
 802                rtc = NULL;
 803                goto exit;
 804        }
 805
 806        clientdata->rtc = rtc;
 807
 808        /* Make sure HT (Halt Update) bit is cleared */
 809        rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 810        if (rc < 0)
 811                goto ht_err;
 812
 813        if (rc & M41T80_ALHOUR_HT) {
 814                if (clientdata->features & M41T80_FEATURE_HT) {
 815                        m41t80_get_datetime(client, &tm);
 816                        dev_info(&client->dev, "HT bit was set!\n");
 817                        dev_info(&client->dev,
 818                                 "Power Down at "
 819                                 "%04i-%02i-%02i %02i:%02i:%02i\n",
 820                                 tm.tm_year + 1900,
 821                                 tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
 822                                 tm.tm_min, tm.tm_sec);
 823                }
 824                if (i2c_smbus_write_byte_data(client,
 825                                              M41T80_REG_ALARM_HOUR,
 826                                              rc & ~M41T80_ALHOUR_HT) < 0)
 827                        goto ht_err;
 828        }
 829
 830        /* Make sure ST (stop) bit is cleared */
 831        rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 832        if (rc < 0)
 833                goto st_err;
 834
 835        if (rc & M41T80_SEC_ST) {
 836                if (i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 837                                              rc & ~M41T80_SEC_ST) < 0)
 838                        goto st_err;
 839        }
 840
 841        rc = m41t80_sysfs_register(&client->dev);
 842        if (rc)
 843                goto exit;
 844
 845#ifdef CONFIG_RTC_DRV_M41T80_WDT
 846        if (clientdata->features & M41T80_FEATURE_HT) {
 847                save_client = client;
 848                rc = misc_register(&wdt_dev);
 849                if (rc)
 850                        goto exit;
 851                rc = register_reboot_notifier(&wdt_notifier);
 852                if (rc) {
 853                        misc_deregister(&wdt_dev);
 854                        goto exit;
 855                }
 856        }
 857#endif
 858        return 0;
 859
 860st_err:
 861        rc = -EIO;
 862        dev_err(&client->dev, "Can't clear ST bit\n");
 863        goto exit;
 864ht_err:
 865        rc = -EIO;
 866        dev_err(&client->dev, "Can't clear HT bit\n");
 867        goto exit;
 868
 869exit:
 870        if (rtc)
 871                rtc_device_unregister(rtc);
 872        kfree(clientdata);
 873        return rc;
 874}
 875
 876static int m41t80_remove(struct i2c_client *client)
 877{
 878        struct m41t80_data *clientdata = i2c_get_clientdata(client);
 879        struct rtc_device *rtc = clientdata->rtc;
 880
 881#ifdef CONFIG_RTC_DRV_M41T80_WDT
 882        if (clientdata->features & M41T80_FEATURE_HT) {
 883                misc_deregister(&wdt_dev);
 884                unregister_reboot_notifier(&wdt_notifier);
 885        }
 886#endif
 887        if (rtc)
 888                rtc_device_unregister(rtc);
 889        kfree(clientdata);
 890
 891        return 0;
 892}
 893
 894static struct i2c_driver m41t80_driver = {
 895        .driver = {
 896                .name = "rtc-m41t80",
 897        },
 898        .probe = m41t80_probe,
 899        .remove = m41t80_remove,
 900        .id_table = m41t80_id,
 901};
 902
 903module_i2c_driver(m41t80_driver);
 904
 905MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
 906MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
 907MODULE_LICENSE("GPL");
 908MODULE_VERSION(DRV_VERSION);
 909
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